JPH0672630B2 - Hydraulic power transmission coupling - Google Patents

Description

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

[Prior Art] The present applicant proposes the following hydraulic power transmission joint in Japanese Patent Application No. 2-40632.

That is, this hydraulic power transmission joint is provided between the input and output shafts that are relatively rotatable, and a plunger pump that is driven by the rotational speed difference between the two shafts and a means that generates flow resistance in the discharge passage of the pump. A power transmission joint in which the transmission torque between the input and output shafts is controlled by the flow resistance, and a cam housing connected to the one shaft and having a cam surface having two or more ridges on its inner surface; A rotor member that is connected to the other shaft and is rotatably accommodated in the cam housing to form a plurality of plunger chambers; A plurality of plungers that are housed movably and that are driven by the cam surface when the two shafts rotate relative to each other; A suction hole and a discharge hole communicating with the Langer chamber; rotatably slidably contacting the rotor member and rotatably positioned by a predetermined angle with respect to the cam housing; In either case of reverse rotation, a plurality of suction ports that act as suction valves and discharge valves depending on the positional relationship between the suction holes and the discharge holes, a valve body having a discharge port, and a discharge passage and a communication passage for each of the discharge ports. And a suction passage connecting the suction port and the low pressure chamber in the joint, and a flow resistance means at the outlet from the high pressure chamber to the low pressure chamber.

[Problems to be Solved by the Invention] However, in such a conventional hydraulic power transmission joint, the discharge ports are communicated with each other by a groove provided on the surface of the rotor shaft or the valve body, and the collecting chamber is connected. Since the high pressure chamber is formed and the rotary seal structure seals the leakage of the high pressure oil by the gap between the inner diameter portion and the outer diameter portion of the valve body, there are the following problems.

(1) Generally, in an axial plunger pump in which a valve element is provided on the thrust surface of the rotor, the hydraulic reaction force of the plunger chamber acting on the rotor causes the valve element and the rotor to come into close contact with each other to prevent oil leakage from the valve section. is 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 that pushes back the rotor against the thrust force and hinders the close contact of the valve portion is generated.

When the oil pressure acting on the surface of the valve is larger than the oil pressure in the plunger chamber, the valve portion cannot be kept in close contact and the valve sealing function is lost.

The oil pressure on the valve surface increases as the area of the discharge port opened on the surface and the area of the groove that communicates with it increases. When the area of the communication groove is increased, it is difficult to adhere the valve part and torque does not occur. .

As a countermeasure, if the discharge port and the communication groove are thin,
There is also a problem that the viscous resistance of oil increases and the torque increases at low temperatures.

Further, it is possible to maintain the close contact of the valve portion by increasing the inner diameter of the valve element and reducing the area of the communication groove, but there is a problem that oil leakage from the inner clearance of the valve element increases as described below. was there.

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

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

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

Conventionally, there has been a problem that the amount of leakage is large, and therefore the torque varies greatly with temperature changes.

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

In the conventional type, which does not have a variable orifice mechanism, an orifice is provided on the outer peripheral portion of the valve element, but it is necessary to shorten the orifice length to reduce the torque change due to temperature. The hole diameter of the part is thickened.

Therefore, there is a problem that the workability is poor and the cost is high.

The present invention has been made in view of such conventional problems, by reducing the oil leakage of the valve portion, without increasing the length of the joint, the torque change due to temperature is small, It is an object of the present invention to provide a hydraulic power transmission joint that has good workability and low cost.

[Means for Solving the Problems] In order to achieve the above-mentioned 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 ridges on the inner surface. A cam housing having a cam surface formed thereon; a rotor coupled to the other shaft and rotatably housed in the cam housing, and having a plurality of plunger chambers formed in the axial direction; A plurality of plungers that are housed in respective chambers so as to be reciprocally movable under the pressure of a return spring and that are driven by the cam surface when the shafts rotate relative to each other; An inlet / outlet hole communicating with the chamber; rotatably slidably contacting the end face of the rotor and positioned in a predetermined relationship with the cam housing, A valve body having a plurality of suction ports and a discharge port formed on the surface thereof to act as a suction valve and a discharge valve according to a positional relationship; and means for generating a flow resistance by the flow of the discharge oil by driving the plunger, In a power transmission joint that transmits torque according to the rotational speed difference between both shafts, a communication groove that is provided on the back surface of the valve body that does not form an intake port and a discharge port, and that communicates with each of the discharge ports, and on the back surface. The lid member is provided in close contact with the flow channel, and flow resistance generating means is provided between the communication groove or the discharge port and the low pressure chamber.

[Operation] In the present invention, the communication groove is provided on the back surface of the valve body that does not form the suction port and the discharge port, and the back surface is closed by the lid member, so that oil leakage of the valve portion can be reduced. . That is, the high-pressure portion that opens on the front surface of the valve body is only the discharge port, and the only one that opens on the back surface is the communication groove. Therefore, the oil pressure to open the valve on the front and back surfaces of the valve body is It becomes smaller than the hydraulic pressure, and the valve portion is kept in close contact.

For this reason, oil leakage in the valve part is reduced, torque fluctuations due to temperature changes can be reduced, and since the valve body is sealed on the front and back surfaces, the axial length for sealing is not required. , The length of the joint does not increase.

Even if the communication groove on the back surface of the valve body must be thinned, the passage from the discharge port to the orifice can be shortened by arranging the flow resistance generating means in multiple orifices. It is possible to reduce the increase in torque due to the increase.

Further, since the orifice is provided so as to penetrate between the communication groove provided on the back surface of the valve body and the suction port provided on the front surface, the machining is facilitated and the cost can be reduced.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

1 to 6 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 an inner surface formed with a cam surface 2 having two or more ridges. The cam 1 is connected to an output shaft 3 and It rotates together with 3. Further, the cam 1 is a cam housing 4
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 plunger chambers 8 are provided inside the plunger chamber 7.
Is stored slidably via a return spring 9. Further, the rotor 5 is formed with a plurality of suction and discharge holes 10 so as to communicate with the respective plunger chambers 7.

11 is a suction port 12, a suction passage 13 and a discharge port 14 on the surface
Is formed, and a communication groove 15 communicating with each of the discharge ports 14 is formed on the back surface of the rotary valve 11. Further, a lid member 16 is provided in close contact with the back surface.

A plurality of orifices (flow resistance generating means) 17 are formed between the communication groove 15 and the suction port 12.

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

The rotary valve 11 constitutes a timing member that determines the opening / closing timing of the intake / discharge hole 10, and the notch 18 and the 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 intake stroke, the positional relationship is such that the intake port 12 of the rotary valve 11 and the intake / discharge hole 10 of the rotor 5 communicate with each other, and the orifice 17, the intake port 12, and the intake passage are provided.
13, oil can be sucked into the plunger chamber 7 through the suction / discharge hole 10 of the rotor 5.

When the plunger is in the discharge stroke, the relationship is the reverse of the suction stroke, and the suction / discharge hole 10 of the rotor 5 communicates with the communication groove 15 via the discharge port 14 of the rotary valve 11.

Reference numeral 20 is a thrust block that 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 with the rotor 5,
After the positioning projection 19 of the rotary valve 11 rotates until it comes into contact with the notch 18 of the cam housing 4, it rotates together with the cam housing 4. As a result, the intake / discharge hole 10 is forcibly opened / closed at a predetermined timing even during normal rotation or reverse rotation.

Reference numeral 23 is an accumulator piston that rotates integrally with the cam housing 4, and the accumulator piston 23 moves according to the internal pressure. Accumulator piston 23 and retainer 24
A return spring 25 is interposed between and.
In addition, 26 is an oil seal, 27 is a stop ring, 28 is a bolt, 29 is an oil injection hole, 30 is a bearing, and 31 is a notch for preventing closing.

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 torque is not transmitted. At this time, the plunger 8 has the return spring 9
Is pressed against 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 axially by the cam surface 2 of the cam 1.

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

The oil pushed out to the discharge port 14 is supplied to the suction port 12 through the communication groove 15 and the orifice 17. At this time,
Due to the resistance of the orifice 17, the hydraulic pressure in the communication groove 15, the discharge port 14 and the plunger chamber 7 rises, and a reaction force is generated in the plunger 8. Against this plunger reaction force, cam 1
Rotating causes torque to be transmitted between the cam 1 and the rotor 5. Each discharge port 14
Are communicated with each other through the communication groove 15, the hydraulic pressures of all the plunger chambers 7 in the discharge stroke are equal.

Further, when the cam 1 rotates, the intake stroke starts, and the suction / discharge hole 10 communicates with the suction port 12, so that the oil in the suction passage 13 is sucked into the plunger chamber 7 via the suction port 12 and the suction / discharge hole 10. The plunger 8 returns along the cam surface 2 of the cam 1.

FIG. 3 shows a state in which the oil in the plunger chamber 7 is supplied to the orifice 17 through the discharge port 14 and the communication groove 15.

Here, as shown in FIG. 4, the rotor pressing force A acting on the rotor 5 is expressed by the following equation.

A≈P × S _p (P is the discharge pressure, S _p is the total area of the plunger chamber 7 in the discharge stroke) On the other hand, the valve surface hydraulic reaction force B acting on the rotary valve 11
Is given by the following equation.

(S _v is the total area of the discharge port 14 or the communication groove 15, S _s is the total area of the seal land 32) In FIG. 4, 33 indicates the pressure distribution.

FIG. 5 (a) shows the arrangement of the discharge port and the seal land in the conventional example, FIG. 5 (b) shows the surface of the valve of the present invention, and FIG.

As shown in (b) and (c) of FIG. 5, S _v and S _s are (a)
Since it becomes smaller, the valve surface hydraulic reaction force B that tries to open the close contact of the valve portion on both the front surface and the rear surface of the rotary valve 11.
Is smaller than the conventional example shown in FIG. 5 (a) and smaller than the rotor pressing force A, so that the valve portion is kept in close contact. As a result, oil leakage of the valve portion can be prevented.

In FIG. 5 (a), 41 is a conventional rotary valve, and 42 is a conventional rotary valve.
Is a suction port, 43 is a discharge port, 44 is a discharge passage, and 45 is a seal land.

Further, in the conventional example, a mechanism for varying the orifice opening degree according to the discharge pressure is provided, and since this mechanism is large, it has to be arranged at the center of the shaft, and high-pressure oil is guided to this center of the shaft. The shaft is provided with the communication groove because of necessity. However, in the case where the variable orifice mechanism is not required as in the present embodiment, the communication groove 15 does not necessarily have to be provided in the shaft portion. It is possible to prevent oil from leaking from the inner diameter portion clearance of 11.

Therefore, oil leakage in the valve portion is reduced, torque fluctuation due to temperature change can be reduced, and since the front and back surfaces of the rotary valve 11 are sealed, an axial length for sealing is required. Not to lengthen the joint as well.

Further, even when the communication groove 15 on the back surface of the rotary valve 11 has to be thinned, as shown in FIG. 6, since a plurality of orifices 17 are arranged in a dispersed manner, the passage from the discharge port 14 to the orifice 17 is shortened. Therefore, the increase in torque due to the increase in oil viscosity at low temperatures can be reduced.

Further, since the orifice 17 is provided so as to penetrate between the communication groove 15 provided on the rear surface of the rotary valve 11 and the suction port 12 provided on the front surface, the machining is facilitated and the cost can be reduced.

[Advantages of the Invention] As described above, according to the present invention, it is possible to reduce the oil leakage of the valve portion, and thus it is possible to reduce the torque fluctuation due to the temperature change.

Also, because the front and back surfaces of the rotary valve are sealed,
No axial length is required for the seal, and the joint length does not increase.

Further, since the passages from the discharge port to the orifices can be shortened by dispersively arranging them in a plurality of orifices, an increase in torque due to an increase in oil viscosity at low temperatures can be reduced.

Further, since the orifice is provided so as to penetrate between the communication groove provided on the back surface of the rotary valve and the suction port provided on the front surface, the machining is facilitated and the cost can be reduced.

[Brief description of 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 showing an oil flow, and FIG. 4 is a valve surface hydraulic reaction force. And (a) to (c) are explanatory views of the valve surface hydraulic reaction force on the front surface and the back surface, and FIG. 6 is a view showing the arrangement of a plurality of orifices. 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, 15 ... Communication groove, 16 ... Lid member, 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, 31 ...... Prevention notch, 32 ...... Seal land, 33 ...... Pressure distribution.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Japanese Patent Laid-Open No. 2-266124 (JP, A) Japanese Patent Laid-Open No. 3-244835 (JP, A) Actual Opening Flat 2-96033 (JP, U)

Claims (3)

[Claims] 1. A cam housing provided between relatively rotatable input / output shafts, connected to said one shaft, and having a cam surface having two or more ridges on its inner side surface; connected to said other shaft. A rotor having a plurality of plunger chambers axially formed therein and rotatably housed in the cam housing; and a plurality of plunger chambers each of which is reciprocally movable under the pressure of a return spring. A plurality of plungers that are housed and driven by the cam surface when the two shafts rotate relative to each other; suction and discharge holes formed in the rotor and communicating with the plunger chamber; rotatably on an end surface of the rotor A plurality of slide valves that are in sliding contact with each other and are positioned in a predetermined relationship with the cam housing and act as suction valves and discharge valves depending on the positional relationship with the suction and discharge holes. A valve body having a suction port and a discharge port formed on its surface; and means for generating a flow resistance by the flow of the discharge oil by driving the plunger; and a power for transmitting a torque according to the rotational speed difference between the two shafts. In the transmission joint, a communication groove that is provided on the back surface that does not form the suction port and the discharge port of the valve body and that communicates with each of the discharge ports, a lid member that is provided in close contact with the back surface, and the communication groove or the A hydraulic power transmission joint comprising flow resistance generating means provided between the discharge port and the low pressure chamber. 2. The hydraulic power transmission joint according to claim 1, wherein the flow resistance generating means is formed by one or a plurality of orifices. 3. The hydraulic power transmission joint according to claim 1, wherein the flow resistance generating means is provided between the communication groove and the suction port.