A self-closing connector in accordance with the invention comprises at least one duct, at least one end orifice, and a sliding valve plate for closing said orifice, the connector is essentially characterized by the fact that said orifice (11, 28, 29, 32) is delimited by at least two lines of sealing (17, 26) disposed on respective closed curves and each belonging to a respective one of two cylindrical surfaces having generator lines extending in the same direction, and in that the sliding valve plate 12 has at least two sealing (12) surfaces belonging to said cylindrical surfaces respectively, with the projection of the section areas of the valve plate which co-operate with respective one of said two sealing lines on a plane P perpendicular to said generator lines having values equal to S'.sub.1 and S'.sub.2. Said section areas are chosen to be equal. This enables the effects of externally-applied pressure to cancel.

The present invention relates to self-closing connectors, i.e. connectors 
for fluid ducts which enable the ends of two ducts which may contain fluid 
under pressure to be interconnected without there being any need to empty 
the ducts and without there being any ingress of fluid of loss of fluid to 
or from the surrounding medium, e.g. air or salt water if the connector is 
used at sea. 
BACKGROUND OF THE INVENTION 
Self-closing connectors are well known and are used in many applications, 
and in particular in those applications requiring a high degree of 
security, for example aeronautics, where they are used for the hydraulic 
controls of an aircraft and for verification thereof. 
Such a connector is essentially constituted by a duct through a body, the 
duct being terminated by a seat-forming orifice, together with a sliding 
valve plate inside the duct and on which a pressure spring acts in such a 
manner as to hold the valve plate against the seat. In broad outline, a 
connector thus comprises a male portion and a female portion which are 
complementary to each other. When these two connector portions are not 
coupled to one another, they are closed by their respective valve plates. 
Under such conditions no fluid can escape from the ducts to which the 
connector portions are associated and, likewise, no gaseous, solid, or 
liquid impurities can enter the ducts. 
When it is necessary to interconnect two ends, they are brought into 
end-to-end contact and pressed against each other, thereby, in a 
preliminary stage, opening a first one of the two valve plates to release 
fluid under pressure from the associated duct, which fluid, in a second 
stage, exerts pressure on the other valve plate and moves it in turn, thus 
opening the orifice with which the second valve plate is associated. The 
second valve orifice could alternatively be opened mechanically. Means are 
also provided for locking the two connectors portions together to prevent 
them from coming apart accidentally. 
As a consequence from the above outline, it can be seen that the two valve 
plates in the two connector portions are displaced from their respective 
seats to provide fluid continuity between their ducts, and the two ducts 
are then interconnected with the above-mentioned advantages. 
However, in some applications, such connectors have a considerable 
drawback. It may happen that connectors with given characteristics, as 
described above, are used in surroundings where the ambient pressure is 
high, and in particular where the ambient pressure may be high enough to 
exert an opening force on the face of a valve plate, in spite of the 
opposing forces exerted thereon by its return spring and by the fluid 
under pressure inside the duct. This applies, in particular, to 
self-closing connectors used underwater at depth. 
Preferred embodiments of the present invention mitigate this drawback and 
provide a self-closing connector of the type having sliding valve plates, 
which connector is insensitive to the pressure of the ambient medium in 
which it is used. 
SUMMARY OF THE INVENTION 
The present invention provides a self-closing connector comprising: 
a duct; 
an orifice at the end of said duct, said orifice being delimited by at 
least two closed curve lines of sealing, each belonging to a respective 
cylindrical surface having generator lines extending in the same 
direction; and 
a valve plate having sealing surfaces at least which belong to said 
respective cylindrical surfaces, each of said sealing surfaces being 
suitable for sliding over a respective one of said sealing lines, the 
projections, on a plane perpendicular to said generator lines, of the 
section areas of the valve plate which co-operate with respective ones of 
said sealing lines being equal in value.

MORE DETAILED DESCRIPTION 
With particular reference to FIG. 1, a first self-closing connector portion 
1 is intended for fitting to the end of a duct for fluid under pressure, 
e.g. for oil under pressure. 
This connector portion comprises a body which is made up of two parts 2 and 
3. A first, or inner part is generally cylindrical and includes a barrel 4 
which is fixed to a base 5 having a fitting for connection to pipework or 
ducting for connection to other pipework or ducting. A second, or outer, 
part 3 is generally constituted by a sleeve 6 which surrounds the barrel 
and which extends slightly beyond the end of the barrel, with the sleeve 6 
and the barrel 4 defining a circular cavity 7 that is closed at the bottom 
by the base 5. One end 8 of the sleeve 6 is fixed, e.g. by three fixing 
pins, to the base 5. The other end 9 of the sleeve includes an inwardly 
directed lip 10 delimiting an inlet 11, which is circular in the present 
example and has a section area S.sub.1 which is substantially equal to the 
central section area S.sub.3 inside the sleeve 6 at 20. 
This connector portion also includes a valve plate or thimble 12 in the 
form of a thimble having an inside cavity 13 which is open at one end 14 
and whose inside diameter is equal to the outside diameter of the barrel 4 
to within mechanical tolerances, thereby enabling the valve thimble to 
slide axially on the end of the barrel in a sealed manner. A sealing ring 
17 provides sealing between the inside face 15 of the valve thimble and 
the outside face 16 of the barrel. The outside surface of the tubular part 
18 of the valve thimble has a surface which is defined in such a manner 
that its outside diameter is equal to within mechanical tolerances to the 
section area S.sub.3 of the inside surface 22 of the middle portion 20 of 
the sleeve. The valve thimble thus slides in sealed manner against said 
inside surface 22, and sealing is obtained by means of a sealing ring 24. 
The end 25 of the valve thimble 12 has the same section area as the section 
area S.sub.1 of the above-defined inlet 11 and can thus slide relative 
thereto in sealed manner as provided by a sealing ring 26 which provides a 
second line of sealing. The end 25 of the valve thimble is of smaller 
outside diameter at 27 than is the main tubular portion 18, and fluid 
communication means are provided through said smaller end portion, e.g. 
holes 28, 29 passing through the side wall of the valve thimble 12. 
The valve thimble 12 as defined above is thus capable of sliding between 
first and second end positions defined by respective stops. The first stop 
is made on the barrel 4 and is constituted by a step 30 in the outside 
wall of the barrel 4 close to the base 5 so that when the valve thimble 12 
slides against the barrel its circular end space 31 it against the step 30 
and thus defines and "open" position as can be seen in FIG. 3 in which the 
end 25 of the thimble has moved out of the inlet 11, and the two holes 28 
and 29 are situated level with the front end 32 of the barrel 4. 
The second, or "closed", position of the valve is shown in FIG. 1, and the 
stop is constituted by a step 33 on the outside surface of the thimble. In 
other words, the reduced diameter end portion 27 of the thimble has two 
steps in it, the first step defines the beginning of the reduced diameter 
portion, and the second, smaller step 33 engages behind the lip 10. 
Resilient means are associated with the valve 12 to urge it towards its 
closed position as shown in FIG. 1, in which the end 25 of the valve 
thimble closes the inlet 11 to the sleeve 6 in a sealed manner. These 
means for exerting a resilient force are advantageously constitued by a 
compression spring 133 which is situated in the circular groove as defined 
above and which bears against the base 5 and the bottom face 31 of the 
valve thimble. Thus one end 34 presses against the bottom 35 of the 
circular groove 7 and the other end 36 presses against the face 31 of the 
valve thimble 12. This spring thus exerts a force which tends to hold the 
valve thimble in abutment against the inwardly directed lip 10 by means of 
its step 33. 
Means are provided through the sleeve 6 to put the circular cavity 7 into 
communication with the surroundings 36 in which the self-closing connector 
is used. Generally speaking, such communication means are obtained by a 
non-sealed connection between the sleeve 6 and the base 5, thereby 
enabling the atmosphere to pass through interstices 38 between these two 
parts. However, in order to clarify the description and to underline the 
need for such communication means, an orifice 39 extends through the wall 
of the sleeve 36, which orifice may advantageously contain a filter (not 
shown) in order to avoid foreign particles entering the groove 7. 
Finally, the outer surface of the sleeve 6 is provided with means for 
associating such a connector portion with a mating connector portion such 
as that shown in FIG. 2, which means may be constituted, for example, by a 
locking ring 40. This ring is not described in greater detail since it is 
known per se and is already used in self-closing connectors of the prior 
art. 
As mentioned in the introduction, such a self-closing connector is intended 
to be used in any ambient medium 37 and regardless of the pressure 
difference which may exist between said medium and the fluid inside the 
duct which is connected by such a self-closing connector. Thus, in order 
to prevent the valve thimble 12 from opening under the effect of 
externally applied pressure, the valve thimble 12 is designed as explained 
above. Let the effective surface area on which the ambient pressure acts 
on the bottom end 25 of the valve thimble be equal to a section S'.sub.1. 
This section S'.sub.1 is defined by the projection of the section defined 
by the second line of sealing (sealing ring 26) on a plane P perpendicular 
to the generator lines which define the various cylindrical parts 
described above, i.e. the barrel, the tubular portion of the thimble, and 
the sleeve 6. 
Let the effective surface area on which ambient pressure acts on the other 
end of the valve be equal to a section of value S'.sub.2. This other 
effective area is defined by the first line of sealing given by the 
sealing ring 17 as projected onto the same plane P. In order to ensure 
that the forces applied to the valve by the ambient medium cancel, the 
sections S'.sub.1 and S'.sub.2 should be equal. Transverse forces are 
absorbed by the transverse surfaces of the sleeve and the barrel and thus 
have no effect. 
Thus, the forces applied to the respective end faces 25 and 31 of the valve 
thimble 12 can be made to be equal and the valve remains in safe 
equilibrium and is never displaced due to the pressure of the medium in 
which it is immersed. The only effective, or net pressure applied to the 
valve thimble is the pressure of the fluid inside the barrel 4 and the 
cavity 13, and the pressure applied by the spring 133. 
The above-described connector portion thus has an inlet defined by two 
lines of sealing respectively defined by the two sealing rings 26 and 17 
which are capable of being closed by the valve thimble 12 by virtue of a 
third line of co-operation defined by the sealing ring 24. 
It is quite conceivable that such a connector portion should be mateable 
with another connector portion which is likewise self-closing. 
One such self-closing connector portion capable of cooperating with the 
connector portion shown in FIG. 1 is shown in FIG. 2. The FIG. 2 connector 
portion has the same advantages as that described with reference to FIG. 
1, in other words external forces acting on the valve plate cancel. 
The self-closing connector portion 50 shown in FIG. 2 comprises two parts 
51 and 52, with the outer part 51 being constituted by a sleeve 53 and the 
inner part 52 being constituted by a barrel 54 associated with a base 55. 
The sleeve 53 and the barrel 54 define a circular cavity 56 similar to 
that defined above and in which a valve member 57 is free to slide. The 
valve member 57 is preferably a body of revolution. In this example, the 
barrel 54 is closed at its end 56 by an end plate 157 whose section is 
identical to the section of the outside surface 58 of the barrel 54. 
However, just before the end plate 157, there are holes such as 59 and 60 
for putting the inside 61 of the barrel 54 into communication with the 
inside of the circular cavity 56. 
The two holes 59 and 60 shown in FIG. 2 lie between two lines of sealing 
respectively defined on two cylindrical surfaces by two sealing rings 62 
and 63 over which the valve member 57 slides. 
The valve is defined so that it is capable of taking up at least two 
positions, a first, or "closed", position as illustrated in FIG. 2 which 
is defined by a first stop 64 constituted by a ring snap-fitted into the 
inside surface of the sleeve 53, with the first position defining the 
position of the valve member 57 so that its inside surface 65 is 
simultaneously in co-operation with both lines of sealing defined by the 
two sealing rings 62 and 63, thereby causing the openings 59 and 60 to be 
closed by the valve member 57. The inside 61 of the barrel 54 cannot then 
be put into communication with the ambient or outside medium 66. 
The second, or "open", position of the valve member 57 is defined by a step 
67 in the outside surface of the barrel 54 against which the end surface 
68 of the valve member 57 comes into abutment. In this position, the valve 
opens the orifices 59 and 60 thus allowing a free passage between the 
inside 61 of the barrel 54 and the inside of the groove 66. 
Means are associated with the valve member 57 to exert a resilient force 
thereon tending to maintain it constantly against the abutment 64, i.e. in 
the position in which the two orifices 59 and 60 are closed. These means 
are constituted by a compression spring 70 disposed inside the 
above-mentioned circular cavity 56. The respective ends 71 and 72 of the 
spring 70 are applied against the end surface 68 of the valve member 57 
and against the bottom 73 of the cavity 56. 
As before, the cavity 56, and more particularly that portion thereof lying 
between the surface 68 of the valve member 57 and the bottom of the groove 
73 is put into communication with the ambient medium 56, either by means 
of a non-sealed join 74 between the sleeve 53 and the base 52 as mentioned 
above, or else by means of an orifice directly provided through the wall 
of the sleeve 53, e.g. an orifice 75 for putting the inside of circular 
groove 56 into communication with the ambient medium 66 in which the 
self-closing connector immersed. As with the orifice 39, the orifice 75 is 
advantageously fitted with a filter in order to prevent foreign bodies 
from entering the groove 56. 
Also as before, such a valve member must not be subjected to a net force by 
the ambient medim in which it is located in order to prevent the valve 
opening at an unwanted moment with the consequent passage of impurities 
into the fluid inside the barrel 54 or the leakage of fluid therefrom. 
As before, in order to achieve this aim, the sections on which the external 
pressure applies, as defined by the projection of two sealing lines 
defined by the sealing rings 62 and 63 on a plane P.sub.1 perpendicular to 
the generator lines of the valve members, should have equal values. With 
this particular valve structure, these two sections are two annular 
sections S'.sub.4 which are strictly identical and thus make it easy for 
the valve member to be in perfect equilibrium, and thus to be unaffected 
by ambient pressure since the ambient pressure acts equally on two 
oppositely directed faces both of which are perpendicular to the generator 
lines of the cylindrical portions of the connector. This is made possible 
by putting the groove 56 into communication with the surrounding medium, 
e.g. via the orifice 75. 
As mentioned above, this self-closing connector portion is intended to 
operate with the self-closing connector portion shown in FIG. 1. In order 
to do this, the end 80 of the valve member 57 has an outside diameter 
defined in its surface 81 which is equal to the inlet section 11 defined 
with reference to FIG. 1. Further, the valve member 57 has a step 82 in 
its outside surface at a distance from its end which is substantially 
equal to the axial extent of the inwardly directed lip 10, so that the 
outside end of the lip 10 engages the stop or step 82 of the valve member 
57. This can be seen more clearly with reference to FIG. 3 which shows the 
results of associating the two self-closing connector portions described 
above with reference to FIGS. 1 and 2. 
The two connector portions 1 and 50 are brought together end-to-end so that 
the end 157 of the barrel 54 comes into contact with the outside surface 
of the bottom 25 of the thimble 12. Then, by exerting pressure, e.g. 
manually, the end 9 of the sleeve 6 is caused to penetrate into the open 
end of the groove 56, and the end 80 of the valve member 57 is caused to 
penetrate into the inlet orifice 11, so that the end 80 cooperates by 
abutment against the end 25 and the valve member 57 cooperates by its 
ouside surface 81 engaging the sealing ring 26. This continues until the 
stop 82 comes into contact with the lip 10 of the sleeve 6. Then, by 
continuing to exert pressure on the two connector portions to bring them 
axially closer together, the barrel 54 penetrates further into the 
connector 1 and pushes back the valve thimble 12. Thus the valve member 57 
slides over the barrel 54 against the force exerted by the spring 70 and 
the two orifices 59 and 60 are opened to allow free passage nto the space 
100 defined in the cavity 7. Likewise, since the valve thimble 12 is 
pushed away from the sealing ring 26, free fluid passage is provided 
between the space 100 and the inside of the barrel 54. The paths taken by 
the fluid are shown by arrows 101 and 102. It can be seen that the paths 
101 and 102 defined between the two barrels 4 and 54 are completely sealed 
and delimited by sealing rings 63, 24 and 26. 
Naturally, the end of the sleeve 53 is located between the locking ring 4 
and the outside surface of the end of the sleeve 6 so as to hold the two 
self-closing connector portions 1 and 50 in mechanical engagement with 
each other in conventional manner.