WO2020057879A1

WO2020057879A1 - Female hydraulic coupling, male hydraulic coupling and combination thereof

Info

Publication number: WO2020057879A1
Application number: PCT/EP2019/072238
Authority: WO
Inventors: Amit SHENDE; Vijay SURVE; Sebastian LAFOND
Original assignee: Eaton Intelligent Power Limited
Priority date: 2018-09-21
Filing date: 2019-08-20
Publication date: 2020-03-26

Abstract

Female hydraulic coupling (1) comprising: - an elongate body (2, 3) comprising a valve guide (4) extending in axial direction, which valve guide (4) debouches with an open end (8) at one end of the body (2, 3); - a valve body (5) guided in the valve guide (4), which valve body (5) is movable in axial direction between a first position and a second position; - spring means (7) arranged between the valve body (5) and the other end of the elongate body (2, 3) to urge the valve body (5) towards the first position; - a bypass channel (9) arranged in the elongate body (2, 3) and extending between the other end of the elongate body (2, 3) and a central portion of the valve guide (4), such that a continuous passage is formed in the elongate body (2, 3), which continuous passage extends from the open end (8) of the valve guide (4) to the other end of the elongate body (2, 3); - a locking sleeve (15), such as a ball retainer, arranged around the first end of the elongate body (2, 3) and movable in axial direction between a third position and a fourth position, which locking sleeve (15) comprises spring means (22) to urge the locking sleeve (15) towards the third position; - a first seal (12) and a second seal (13) arranged on the valve body (5) to seal the valve body (5) to the valve guide (4) in the first position, wherein the first seal (12) and second seal (13) are positioned in said first position on opposite sides of the opening (11) of the bypass channel (9) at the central portion of the valve guide (4).

Description

Female hydraulic coupling, male hydraulic coupling and combination thereof

The invention relates to a female hydraulic coupling, such as a flat face female hydraulic coupling. Such a flat face female hydraulic coupling is for example known from PCT/EP2018/052000. This known coupling is designed to minimize the force required to couple the flat face female hydraulic coupling when under pressure. In this known female coupling a valve stem is stationary arranged, which results in a pressure drop and reduces flow through the coupling.

Furthermore, the known female coupling has two telescopically sliding sleeves, which need to be properly sealed and this complicates the design of the coupling to ensure reliability.

This known flat face female hydraulic coupling is however not suited to be coupled when also the corresponding flat face male hydraulic coupling is under pressure. When the male coupling is inserted into the female coupling, the fluid passage already starts to open, before both couplings are mechanically locked to each other. So, at least part of the hydraulic system should be depressurized before a coupling could reliably take place.

It is an object of the invention to reduce or even remove the above mentioned disadvantages.

This object is achieved according to the invention with a female hydraulic coupling comprising:

- an elongate body comprising a valve guide extending in axial direction, which valve guide debouches with an open end at one end of the body;

- a valve body guided in the valve guide, which valve body is movable in axial direction between a first position and a second position;

- spring means arranged between the valve body and the other end of the elongate body to urge the valve body towards the first position;

- a bypass channel arranged in the elongate body and extending between the other end of the elongate body and a central portion of the valve guide, such that a continuous passage is formed in the elongate body, which continuous passage extends from the open end of the valve guide to the other end of the elongate body;

- a locking sleeve, such as a ball retainer,

arranged around the first end of the elongate body and movable in axial direction between a third position and a fourth position, which locking sleeve comprises spring means to urge the locking sleeve towards the third position;

- a first seal and a second seal arranged on the valve body to seal the valve body to the valve guide in the first position, wherein the first seal and second seal are positioned in said first position on opposite sides of the opening of the bypass channel at the central portion of the valve guide.

With the female hydraulic coupling according to the invention, the valve body is urged towards the first position, such that the first seal and second seal close off the bypass channel. Only when a male hydraulic coupling is inserted into the female hydraulic coupling of the invention and only when the locking sleeve arrives at the fourth position, in which a full coupling of the male hydraulic coupling with the female hydraulic coupling is achieved.

Although the bypass channel is no longer sealed, the valve body will still largely blocks the bypass channel such that the pressure in the valve guide at the open end can only increase gradually. This allows for sufficient time to provide a reliable mechanical coupling between the female coupling and the male coupling.

As soon as the pressure has increased to a certain threshold, the pressure will be sufficient to push the valve body against the pressure of the spring means towards the second position fully freeing the bypass channel and allowing for maximum flow through the female hydraulic coupling.

A preferred embodiment of the female hydraulic coupling according to the invention comprises a movable pin arranged in the elongate body and extending sealingly through the elongate body and extending between the locking sleeve and the valve body, wherein the movable pin is moved by the locking sleeve arriving at the fourth position to move the valve body towards a position in the direction of the second position with the first seal and second seal on the same side of the opening of the bypass channel at the central portion of the valve guide to open the bypass channel.

The movable pin will push the valve body in a defined way towards the second position such that the valve body no longer seals the bypass channel.

Another embodiment of the female hydraulic coupling according to the invention the valve guide comprises a helical groove arranged in the surface with which the first and second seal are in sealing contact with, which helical groove extends from the opening in the direction of the open end to a fifth axial position.

The helical groove will provide a small leak as soon as the valve body is moved with the second seal over the helical groove. This will start pressure equalization between the female hydraulic coupling and a male coupling with which the female hydraulic coupling is coupled.

A preferred embodiment of the female hydraulic coupling according to the invention, further comprises:

- a locking body coaxially arranged around the locking sleeve and fixedly to the elongate body, wherein the locking body comprises at least one radially extending through hole housing a locking ball; and

- a lock operating sleeve arranged slidably and coaxially around the locking body, wherein the lock operating sleeve has a profiled inner surface to urge the locking balls into their respective radially extending through holes.

When a male hydraulic coupling, provided with an external groove, is inserted into the female hydraulic coupling according to the invention, the locking balls will be accommodated partially in said groove upon full insertion of the coupling. The lock operating sleeve having the profiled inner surface then can slide over the through holes preventing the locking balls to be pushed back. This ensures a reliable coupling, which can only be decoupled by shifting the lock operating sleeve such that the locking balls can return back into the through holes.

In a further preferred embodiment of the female hydraulic coupling according to the invention a bleed port is arranged in the elongate body extending from the valve guide to the outer surface of the elongate body and positioned near the other end of the elongate body.

Because the valve body is provided with the first and second seal, air present between the other end of the valve guide and the valve body will be compressed when the valve body is moved to the second position. With the bleed port, this compressed air can be bled to the exterior of the coupling .

By designing the dimensions of the bleed port, the speed with which the valve body is pushed towards the second position by the hydraulic pressure can be controlled.

The invention also relates to a male hydraulic coupling. Such a male hydraulic coupling is for example known from PCT/EP2018/051998. Also in this known coupling a

telescopic arrangement of the valve body is provided, which requires additional attention for the seals. Furthermore, the male hydraulic coupling is already opened fully when the mechanical coupling is about to be made.

So, with said known flat face male hydraulic

coupling the pressure needs to be removed from the male coupling in order to safely couple said known coupling

especially when high working pressures of 350 bar are used.

In line with the already stated object to reduce or even remove the disadvantages of the prior art, this object is also achieved with a male hydraulic coupling comprising:

- a bypass channel arranged in the elongate body and extending between the other end of the elongate body and a central portion of the valve guide, wherein the bypass channel (41) ends in opening, such that a continuous passage is formed in the elongate body, which continuous passage extends from the open end of the valve guide to the other end of the elongate body;

wherein the elongate body has at the one end an external groove for connection with locking means of a female hydraulic coupling.

When the male hydraulic coupling is inserted into a female hydraulic coupling, such as according to the invention, the valve body is pushed towards the other end of the elongate body .

Only when the mechanical connection between the male and female couplings is made and the pressure within the couplings is increased, the valve body of the male hydraulic coupling will be moved against the spring means towards the second position opening the bypass channel.

A preferred embodiment of the male hydraulic

coupling further comprises:

- a first seal arranged in the valve guide between the central portion and the other end of the elongate body to seal the the valve body in the valve guide (33) ;

- a second seal and a third seal arranged in the valve guide between the central portion and the one end of the elongate body.

When the male hydraulic coupling is inserted into the female hydraulic coupling the valve body is pushed towards the other end of the elongate body. As a result, the sealing action of the second seal is transferred on to the part of the female coupling extending into the valve guide, while the bypass channel is still sealed by the first and second seal sealing onto the valve body of the male coupling.

In another embodiment of the male hydraulic coupling according to the invention, the valve body is provided with a helical groove extending from the open end along a part of the length of the valve body and ends before the third seal with the valve body in the first position.

This helical groove provides a flow path from the male hydraulic coupling towards the female hydraulic coupling, when the male hydraulic coupling is inserted partially into the female coupling. By designing the helical groove small, the flow and pressure rise will be limited, such that an operator has sufficient time to fully couple and latch both couplings .

Another preferred embodiment of the male hydraulic coupling according to the invention, further comprises:

- a first seal arranged in the valve body at a first end of the valve body to seal the valve body in the valve guide in the first position between the open end and the opening of the bypass channel;

- a second seal arranged in the valve body at a second end of the valve body to seal the valve body in the valve guide in the first position between the opening of the bypass channel and the end of the valve guide distal from the open end;

- a helical groove arranged in the surface with which the first and second seal are in sealing contact with, which helical groove extends from the opening in the direction of the open end to a sixth axial position.

When the valve body of the male hydraulic coupling is moved towards the second position by the valve guide of the female hydraulic coupling, the first seal of the valve body will be moved over the helical groove, such that a small leak is created and the pressure can be equalized between the male and female hydraulic couplings.

A preferred embodiment of the male hydraulic

coupling according to the invention, further comprising a projection arranged on the valve body, which projection extends out of the valve guide in the first position of the valve body and wherein the diameter of the projection is smaller than the diameter of the open end.

The protrusion provides with the open end a further alignment of both couplings and also ensures that the valve body of the female coupling is already moved somewhat towards the second position when the male coupling is inserted.

By balancing the springs of both male and female coupling, it can be ensured that both valve bodies are at a position, where the respective seal has moved over the

respective helical groove, such that a leak is created in both couplings at the same time.

It is also possible with the protrusion to move the valve body of the female coupling over such a distance, that a leak is created in the female coupling even before the valve body of the male coupling starts to move from the first position. This ensures that when the pressure is present on the male coupling, the female coupling is already in a state in which leaking fluid from the male coupling can be absorbed via the leak along the helical groove in the female coupling.

Yet another embodiment of the male hydraulic

coupling according to the invention, further comprises a rod extending axially and sealingly through the valve body with a first end up to the open end and wherein the rod is fixedly arranged with the second end to the elongate body. The rod provides for a defined movement of the valve body of the female coupling, independent of the spring force and ensures that in a specific state of coupling the position of the valve body of the female coupling is defined.

In a preferred embodiment of the male hydraulic coupling according to the invention a bleed port is arranged in the elongate body extending from the valve guide to the outer surface of the elongate body and positioned near the other end of the elongate body.

Similarly to the bleed port of the female hydraulic coupling, the dimensions of the bleed port of the male

hydraulic coupling allow for controlling the speed with which the valve body is pushed by hydraulic pressure towards the second position.

The invention further relates to a combination of a female hydraulic coupling according to the invention and a male hydraulic coupling according to the invention,

- wherein the one end of the female elongate body extends into the open end at the one end of the male elongate body and is sealed by the second seal of the male hydraulic coupling;

- wherein the locking sleeve is in the fourth position in contact with the male elongate body and the female valve body is moved towards a position in the direction of the second position by the movable pin.

In a preferred embodiment of the combination

according to the invention at least one locking ball is partly accommodated in the external groove of male hydraulic coupling and partly in the through hole of the locking body. These and other features of the invention will be elucidated in conjunction with the accompanying drawings.

Figure 1 shows a cross-sectional view an embodiment of a flat face female hydraulic coupling according to the invention .

Figure 2 shows a cross-sectional view an embodiment of a flat face male hydraulic coupling according to the invention .

Figures 3 - 5 show a first combination of the coupling according to figures 1 and 2 in three different states .

Figures 6A - 6D show a second combination according to the invention in four different states.

Figures 7A - 7D show a third combination according to the invention in four different states.

Figures 8A - 8D show a fourth combination according to the invention in four different states.

Figure 1 shows an embodiment 1 of a flat face female hydraulic coupling according to the invention. The coupling 1 has an elongate body out of two parts 2, 3. In the elongate body 2, 3 a valve guide 4 is arranged in which a valve body 5 is guided. The valve guide 4 has a closed end 6 on which a spring 7 is supported, which spring 7 urges the valve body 5 towards an open end 8 of the valve guide 4.

A bypass channel 9 is arranged between a coupling end 10 of the coupling 1 and a central portion of the valve guide 4, where the bypass channel 9 ends in opening 11. The valve body 5 is provided with a first seal 12 and a second seal 13, such that the valve body 5 seals the bypass channel 9 in the shown first position of the valve body 5.

A movable pin 14 is sealingly arranged in the elongate body 2, 3 and said movable pin 14 coacts with the locking sleeve 15 and a shoulder 16 on the valve body 5. The locking sleeve 15 is urged by a spring 22 towards the shown third position. A locking body 17 is arranged around the locking sleeve 15. The locking body 17 is provided with radial through holes in which locking balls 18 are accommodated. A lock operating sleeve 19 is slidably and coaxially arranged around the locking body 17. The lock operating sleeve 19 has a profiled inner surface such that a groove 20 is formed.

Furthermore, a bleed port 21 is arranged in the elongate body 2, 3 such that air from behind the valve body 5 can be vented to the outside of the coupling 1. This bleed port 21 ends into a protector groove 45. This protector groove 45 ensures that the first seal 12 is not damaged by the bleed port 21, when the valve body 5 with the first seal 12 is moved into the elongate body 3.

Figure 2 shows an embodiment 30 of a flat face male hydraulic coupling according to the invention. The coupling 30 has an elongate body out of two parts 31, 32. In the elongate body 31, 32 a valve guide 33 is arranged in which a valve body 34 is guided. The valve guide 33 has a closed end 35 on which a spring 36 is supported, which spring 36 urges the valve body 34 towards an open end 37 of the valve guide 33.

A bypass channel 41 is arranged between a coupling end 42 of the coupling 30 and a central portion of the valve guide 33, where the bypass channel 41 ends in opening 43.

A first seal 38 is arranged in the valve guide 33 between the opening 43 in the central portion and the other end of the elongate body 31, 32 to seal the the valve body 34 in the valve guide 33. A second seal 39 and a third seal 40 are arranged in the valve guide 33 between the opening 43 in the central portion and the open end 37 of the elongate body. The seals 38 and 40 are dimensionally close enough in diameter to allow that valve 34 is pressure balanced, such that only a small force is required to move the valve 34. This also applies to the seals 12 and 13, which allow valve 5 to be moved with low force.

Furthermore a bleed port 47 is arranged in the elongate body 31, 32 extending between the closed end 35 of the valve guide 33 and the outside of the coupling 30.

The elongate body 31, 32 has at the one end an external groove 44 for connection with locking means 18 of a flat face female hydraulic coupling 1.

The elongate body 31, 32 is furthermore provided with a compatibility groove 46, which allows the flat face male hydraulic coupling to be coupled to existing standard couplings, which are not according to the invention. As a result the male coupling 30 can already be applied to existing hydraulic installations, even when the female hydraulic coupling according to the invention is not yet applied in the hydraulic installation.

On the end of the valve body 34 distal from the flat face 37, a lock ring 48 is provided. When the valve body 34 is pushed fully into the elongate body 31, 32, the lock ring 48 will expand into the groove 49, such that the valve body 34 is locked in said position.

Figure 3 shows a first stage of connecting a flat face female hydraulic coupling 1 and a flat face male

hydraulic coupling 30. One end of the elongate male body 31,

32 is inserted into the open end of the valve guide 4 of the female elongate body 2, 3. The second seal 39 of the male coupling 30 seals the female elongate body 2, 3 onto the valve guide 33 of the male coupling 30. Simultaneously the valve body 34 of the male coupling 30 is moved against the spring force of the spring 36 from the first position (as shown in figure 2) towards the second position. As the first seal 38 and third seal 40 still seal onto the valve body 34, the opening 43 of the bypass channel 41 is still closed. Also at the female coupling 1 the first seal 12 and second seal 13 close the opening 11 of the bypass channel 9.

Both valve bodies 5, 34 are at balanced condition, because there is no annular area present on which the oil pressure can build force. As a result, the valve bodies 5, 34 still remain in their position.

In figure 4 the male coupling 30 is inserted further into the female coupling 1, such that the locking balls 18 engage in the groove 44 of the male coupling 30 and a

mechanical coupling is achieved. The lock operating sleeve 19 prevents the locking balls 18 from being pushed out of the groove 44.

At the same time, the locking sleeve 15 is fully moved towards the fourth position, such that the movable pin 14 is engaged and acts on the shoulder 16 of the valve body 5 of the female coupling 1. As a result the valve body 5 is moved partially towards the second position, such that the first seal 12 and second seal 13 are moved towards one side of the opening 11 of the bypass channel 9 and the opening 11 is no longer sealed. As a result a pressure can build in the valve guide 4.

When sufficient pressure has been built in the valve guide 4 or opening 11, the force of the spring 7 will be overcome such that the valve body 5 of the female coupling 1 is moved into the second position. Also the force of the spring 36 will be overcome and the valve body 34 of the male coupling 30 will be moved into the second position, as is shown in figure 5.

As a result both bypass channels 9 and 41 of the female coupling 1 and male coupling 30 respectively are fully opened and the connection of both couplings 1, 30 is

completed .

In case the oil flow is from the male hydraulic coupling 30 towards the female hydraulic coupling 1, a helical groove 50 is provided on the valve body 34 of the male

hydraulic coupling 30. When the valve body 34 is pushed inwardly to a position as shown in figure 3, the helical groove 50 will extend past the third seal 40. Due to the small size of the helical groove 50, the oil flow and the pressure increase will be minimal. This allows for the operator the fully latch the coupling 1, 30 in the position as shown in figure 4. In this position the female hydraulic coupling 1 is provided with a flow path as described above and with the flow path provided with the helical groove 50 the pressure is allowed to build up further, such that both valve bodies 5, 34 can be moved away from each other as described above and shown in figure 5.

Figures 6A - 6D show a second combination 60 according to the invention of a female hydraulic coupling 61 and a male hydraulic coupling 62 in four different states.

The female coupling 61 corresponds largely to the coupling 1 of figure 1, while the male coupling 62 corresponds largely to the coupling 30 of figure 2. Similar parts are designated with the same reference signs.

The female coupling 61 differs from the coupling according to figure 1 in that the valve body 63 has the first seal 12 and second seal 13 arranged on opposite ends of the valve body 63, such that the valve body 63 has to move over a longer path to have the second seal 13 pass the opening 11 of the bypass channel 9.

The male coupling 62 differs from the coupling according to figure 2 in that the first seal 64 and second seal 65 are arranged in the valve body 66. A third seal 40 is still arranged in the elongate body 31, 32. The valve body 66 is furthermore provided with a protrusion 67.

Figure 6B shows the state in which the male hydraulic coupling 62 is slightly inserted into the female hydraulic coupling 61. The spring 7 of the female coupling 61 and the spring 36 of the male coupling 62 are balanced such that both the valve body 63 and the valve body 66 are moved out of the first position towards the second position.

The seals 12, 13 of the female coupling 61 still seal the opening 11 of the bypass channel 9 and the seals 64, 65 of the male coupling 62 still seal the opening 43 of the bypass channel 41.

In figure 6C, the male coupling 62 is inserted further into the female coupling 61. Due to the balanced springs 7, 36, the second seal 13 (removed in this view for clarity) of the valve body 63 has passed the helical groove 68 (see also figure 6D) such that a small leak is provided from the bypass channel 9 to the open end 8 of the female coupling 61. At the same time, due to the balanced springs 7, 36, the first seal 64 (removed in this view for clarity) of the valve body 66 has passed the helical groove 69 (see also figure 6D) such that a small leak is provided from the bypass channel 41 to the open end 37 of the male coupling 62.

These leaks along the helical grooves 68, 69 allow for a pressure equalization between the female hydraulic coupling 61 and the male hydraulic coupling 62.

In figure 6D the male coupling 62 is fully inserted into the female coupling 61 such that a mechanical coupling is obtained through the locking sleeve 19 and the locking ball 18.

As soon as the pressure has sufficiently equalized, the hydraulic pressure will push the valve bodies 63, 66 to their respective second positions against the respective springs 7, 36 and a full connection is obtained.

Figures 7A - 7D show a third combination according to the invention of a female hydraulic coupling 61, which is the same as shown in figures 6A-6D, and a male hydraulic coupling 70 in four different states.

The male coupling 70 corresponds largely to the coupling 62 of figure 6A-6D. Similar parts are designated with the same reference signs.

The male hydraulic coupling 70 has a valve body 71 with a first seal 64 and a second seal 65. A protrusion 72 is provided, which is longer than the protrusion 67 of the valve body 66 of the male coupling 62. Furthermore, the spring 73 of the female coupling 61 is no longer balanced with the spring 74 of the male coupling 70.

The spring 74 is stronger than the spring 7, such that upon further insertion of the male coupling 70, as shown in figure 7B, the valve body 63 is only moved and to a

position wherein the second seal 13 passes the helical groove 68 (see also figure 7D) .

When the protrusion 72 is fully inserted into the open end 8 of the valve guide 4, the further insertion of the male coupling 70 into the female coupling 61 will cause the valve body 71 to move from the first position towards the second position. When the male coupling 70 is fully inserted into the female coupling 61, a mechanical coupling can be established with the locking ball 18 and the locking sleeve 19. At the same time, the first seal 64 of the valve body 71 will have passed the helical groove 75 (see also figure 7D) such that a leak is provided in the male coupling 70. Together with already present leak in the female coupling 61, a

pressure equalization can take place, which will press the valve bodies 63, 71 to their respective second positions and a full coupling is achieved.

Figures 8A - 8D show a fourth combination according to the invention of a female hydraulic coupling 61, which is the same as shown in figures 6A-6D, and a male hydraulic coupling 80 in four different states.

The male coupling 80 corresponds largely to the coupling 62 of figure 6A-6D. Similar parts are designated with the same reference signs.

The male coupling 80 has a valve body 81 in which the first seal 64 and the second seal 65 are arranged. The valve body 81 is provided with a protrusion 82. Furthermore, a rod 83 arranged with one end to the elongate body 31, 32 and with the other end extending through the valve body 81 up to the end of the protrusion 82.

As shown in figure 8B, the rod 83 will push, upon insertion of the male coupling 80 into the female coupling 61, the valve body 63 of the female coupling 61 from the first position towards the second position. The second seal 13 (not shown for clarity) is moved passed the helical groove 68 such that a small leak is created in the female coupling 61.

When the male coupling 80 is inserted fully into the female coupling 61, as shown in figure 8C, and a mechanical locking can be obtained with the locking ball 18 and locking sleeve 19, the valve guide 4 of the female coupling 61 will have moved the valve body 81 from the first position towards the second position, such that the first seal 64 (not shown for clarity) will be moved passed the helical groove 84 (see also figure 8D) such that a small leakage is created in the male coupling 80.

The leakage in both the female coupling 61 and male coupling 80 allow for pressure equalization and will cause the equalized hydraulic pressure to press the valve bodies 63, 81 into the second position.

As the rod 83 of the male coupling 80 causes the valve body 63 of the female coupling 61 to shift initially, the spring 85 could be of less strength, such that the

hydraulic pressure can move the valve body 81 at a lower pressure. The same applies for the strength of the spring 7 of the female coupling 61.

Claims

1. Female hydraulic coupling (1; 61) comprising:

- an elongate body (2, 3) comprising a valve guide (4) extending in axial direction, which valve guide (4) debouches with an open end (8) at one end of the body (2, 3);

- a valve body (5; 63) guided in the valve guide (4), which valve body (5) is movable in axial direction between a first position and a second position;

- spring means (7) arranged between the valve body (5; 63) and the other end of the elongate body (2, 3) to urge the valve body (5; 63) towards the first position;

- a bypass channel (9) arranged in the elongate body (2, 3) and extending between the other end of the elongate body (2, 3) and a central portion of the valve guide (4), such that a continuous passage is formed in the elongate body (2, 3), which continuous passage extends from the open end (8) of the valve guide (4) to the other end of the elongate body (2, 3) ;

- a locking sleeve (15), such as a ball retainer, arranged around the first end of the elongate body (2, 3) and movable in axial direction between a third position and a fourth position, which locking sleeve (15) comprises spring means (22) to urge the locking sleeve (15) towards the third position;

- a first seal (12) and a second seal (13) arranged on the valve body (5) to seal the valve body (5) to the valve guide (4) in the first position, wherein the first seal (12) and second seal (13) are positioned in said first position on opposite sides of the opening (11) of the bypass channel (9) at the central portion of the valve guide (4) .

2. Female hydraulic coupling (1) according to claim 1, further comprising:- a movable pin (14) arranged in the elongate body (2, 3) and extending sealingly through the elongate body (2, 3) and extending between the locking sleeve (15) and the valve body (5), wherein the movable pin (14) is moved by the locking sleeve (15) arriving at the fourth position to move the valve body (5) towards a position in the direction of the second position with the first seal (12) and second seal (13) on the same side of the opening (11) of the bypass channel (9) at the central portion of the valve guide (4) to open the bypass channel (9) .

3. Female hydraulic coupling (61) according to claim

1, wherein the valve guide (4) comprises a helical groove (68) arranged in the surface with which the first and second seal (12, 13) are in sealing contact with, which helical groove (68) extends from the opening (11) in the direction of the open end (8) to a fifth axial position.

4. Female hydraulic coupling (1; 61) according to claim any of the preceding claims, further comprising:

- a locking body (17) coaxially arranged around the locking sleeve (15) and fixedly to the elongate body (2, 3), wherein the locking body (17) comprises at least one radially extending through hole housing a locking ball (18); and

- a lock operating sleeve (19) arranged slidably and coaxially around the locking body (17), wherein the lock operating sleeve (19) has a profiled inner surface (20) to urge the locking balls (18) into their respective radially extending through holes.

5. Female hydraulic coupling (1; 61) according to claim any of the preceding claims, wherein a bleed port (21) is arranged in the elongate body (2, 3) extending from the valve guide (4) to the outer surface of the elongate body (2, 3) and positioned near the other end of the elongate body (2, 3) .

6. Male hydraulic coupling (30; 62; 70; 80) comprising :

- an elongate body (31, 32) comprising a valve guide (33) extending in axial direction, which valve guide (33) debouches with an open end (37) at one end of the body (31,

32) ;

- a valve body (34; 66; 71; 81) guided in the valve guide (33), which valve body (34; 66; 71; 81) is movable in axial direction between a first position and a second

position;

- spring means (36; 74; 85) arranged between the valve body (34; 66; 71; 81) and the other end (35) of the elongate body (31, 32) to urge the valve body (34; 66; 71; 81) towards the first position;

- a bypass channel (41) arranged in the elongate body (31, 32) and extending between the other end of the elongate body (31, 32) and a central portion of the valve guide (33), wherein the bypass channel (41) ends in opening (43) , such that a continuous passage is formed in the elongate body (31, 32), which continuous passage extends from the open end (37) of the valve guide (33) to the other end of the elongate body (31, 32);

wherein the elongate body (31, 32) has at the one end an external groove (44) for connection with locking means (18) of a female hydraulic coupling (1) .

7. Male hydraulic coupling (30) according to claim 6, further comprising:

- a first seal (38) arranged in the valve guide (33) between the central portion and the other end of the elongate body (31, 32) to seal the the valve body (34) in the valve guide (33) ;

- a second seal (39) and a third seal (40) arranged in the valve guide (33) between the central portion and the one end of the elongate body (31, 32) .

8. Male hydraulic coupling (30) according to claim 6 or 7, wherein the valve body (34) is provided with a helical groove (50) extending from the open end (37) along a part of the length of the valve body (34) and ends before the third seal (40) with the valve body (34) in the first position.

9. Male hydraulic coupling (62; 70; 80) according to claim 7, further comprising:

- a first seal (64) arranged in the valve body (66; 71; 81) at a first end of the valve body (66; 71; 81) to seal the valve body (66; 71; 81) in the valve guide in the first position between the open end (37) and the opening (43) of the bypass channel (41);

- a second seal (65) arranged in the valve body (66; 71; 81) at a second end of the valve body (66; 71; 81) to seal the valve body (66; 71; 81) in the valve guide in the first position between the opening (43) of the bypass channel (41) and the end of the valve guide distal from the open end (37);

- a helical groove (69; 75; 84) arranged in the surface with which the first and second seal (64, 65) are in sealing contact with, which helical groove (69; 75; 84) extends from the opening (43) in the direction of the open end (37) to a sixth axial position.

10. Male hydraulic coupling (62; 70; 80) according to claim 9, further comprising a projection (67; 72; 82) arranged on the valve body (66; 71; 81), which projection (67; 72; 82) extends out of the valve guide in the first position of the valve body (66; 71; 81) and wherein the diameter of the projection (67; 72; 82) is smaller than the diameter of the open end ( 37 ) .

11. Male hydraulic coupling (80) according to claim 9, further comprising a rod (83) extending axially and

sealingly through the valve body (81) with a first end up to the open end (37) and wherein the rod (83) is fixedly arranged with the second end to the elongate body (32) .

12. Male

hydraulic coupling (30) according to any of the claims 6 - 11, wherein a bleed port (47) is arranged in the elongate body (31, 32) extending from the valve guide (33) to the outer surface of the elongate body (31, 32) and positioned near the other end of the elongate body (31, 32) .

13. Combination of a female hydraulic coupling (1;

61) according to any of the claims 1 - 5 and a male hydraulic coupling (30; 62; 70; 80) according to claim 6 - 12,

- wherein the one end of the female elongate body (2, 3) extends into the open end (37) at the one end of the male elongate body (31, 32) and is sealed by a seal (40) arranged in the open end of the male hydraulic coupling (30;

62; 70; 80);

- wherein the locking sleeve (15) is in the fourth position in contact with the male elongate body (31, 32) .

14. Combination according to claim 13 with a female hydraulic coupling (1; 61) according to claim 5 or 6 wherein at least one locking ball (18) is partly accommodated in the external groove (44) of male hydraulic coupling (30; 62; 70;

80) and partly in the through hole of the locking body (17) .