Remote filling device for an oil tank
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a device for the remote filling of an oil tank, and is particularly applicable to the oil tanks of aircraft turboshaft engines. 
     2. Summary of the Prior Art 
     For safety and size reasons, the oil tanks of aircraft engines are often situated in places which are difficult to access. Filling such a tank must therefore be made from a distance by connecting a supply pipe to a filler hole of the tank. In addition, an excess oil removal pipe is generally connected to the tank. Thus, when the oil reaches a certain level in the tank, it flows along the excess oil removal pipe, thus triggering the closure of the supply pipe. 
     Such an arrangement is described in documents US-A-2,710,019 and FR-A-2 633 007. 
     Generally, remote filling oil tanks require a certain sequence to be followed when connecting the pipes. Indeed, when filling such a tank, it is necessary first to connect the excess oil removal pipe along which the oil flows when the tank is full, then the supply pipe, so as to lessen the risk of overfilling the tank. 
     Several things may occur if this sequence is not followed. Failure to connect the excess oil removal pipe results in the tank being overfilled. Escape of excess oil may then occur along pipes such as the degassing ducting, the role of which is not to permit oil circulation. The consequences of such overfilling are various, depending on the aircraft engine involved, but in particular there is a risk of over-heating and leakage. 
     It is an object of the present invention therefore to provide a filling device which prevents the connection of the supply pipe when the excess oil removal pipe has not been connected. A further object is for such a device to effect closure of the degassing ducting when the tank is being filled. 
     SUMMARY OF THE INVENTION 
     According to the invention, there is provided a device for the remote filling of an oil tank having an internal space for containing the oil, and degassing means, said device being adapted to be attached to said tank and comprising: 
     remote oil filling means comprising an oil inlet nozzle arranged to be open to said internal space of said tank, a detachable oil supply pipe adapted to be connected to said inlet nozzle, and automatic closure means for said inlet nozzle; 
     excess oil removal means comprising an outlet nozzle arranged to be open to said internal space of said tank, a detachable removal pipe adapted to be connected to said outlet nozzle, and automatic closure means for said outlet nozzle; and 
     locking means interposed between said automatic closure means for said outlet nozzle and said automatic closure means for said inlet nozzle which prevents connection of said oil supply pipe to said inlet nozzle when said removal pipe is not connected to said outlet nozzle. 
     Preferably, the automatic closure means for said inlet nozzle comprises an inlet slide valve slidably mounted in said inlet nozzle, and first resilient means normally maintaining said inlet slide valve in a position closing said inlet nozzle, connection of said supply pipe to said inlet nozzle moving said inlet slide valve into an open position. 
     Similarly, the automatic closure means for the outlet nozzle preferably comprises an outlet slide valve slidably mounted in said outlet nozzle, and second resilient means normally maintaining said outlet slide valve in a position closing said outlet nozzle, connection of said removal pipe to said outlet nozzle moving said outlet slide valve into an open position. 
     In a preferred embodiment of the invention, the locking means comprises a locking member and third resilient means biassing said locking member into engagement with said outlet slide valve, said locking member occupying a position wherein it locks said inlet slide valve in its closed position when said removal pipe is not connected to said outlet nozzle, and said locking member occupying a position wherein said inlet slide valve is free to move to its open position when said removal pipe is connected to said outlet nozzle. 
     Preferably, the locking member is a slidably mounted member having a first end which fits into a notch in the inlet slide valve when the inlet and outlet slide valves are in their closed positions, and a second end which is held in engagement with a cam surface of the outlet slide valve by the action of said third resilient means, said cam surface allowing said locking member to move so that said first end moves out of said notch when said outlet slide valve is moved to its open position by connection of said removal pipe to said outlet nozzle. 
     Preferably, the inlet slide valve has transverse passage means enabling air to flow between the internal space of the tank and the degassing means when the inlet slide valve is in the closed position. However, when the inlet slide valve is in the open position, the transverse passage means is closed and access to the degassing means from the interior of the tank is impossible. 
     The device in accordance with the invention enables the overfilling of a remotely filled oil tank to be avoided. 
     Other features and advantages of the invention will become apparent from the following description of a preferred embodiment, given by way of example and with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagrammatic view of an aircraft engine oil tank to which a remote filling device in accordance with the invention is fitted. 
     FIG. 2 is a sectional view of a preferred embodiment of the remote filling device of the invention fitted to an oil tank. 
     FIGS. 3A, 3B and 3C are diagrammatic views of the device of FIG. 2 showing the device in different operating positions. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The oil tank 2 shown in FIG. 1 comprises an internal space for containing oil, into which opens an oil inlet duct 4 for manual filling, an inlet duct 6 for oil coming from a used oil recovery system (not shown), and an outlet duct 8 for the delivery of oil to an engine supply circuit (not shown). 
     Also opening into the upper part of the tank 2 is a degassing pipe 10 for the flow of air between the inside of the tank 2 and a degassing device which is not shown. 
     A low level detection device 12, partly situated in the lower part of the tank 2 is provided for detecting when the oil in the tank reaches a minimum level N2 necessary for a suitable supply to the engine supply circuit to be maintained. 
     The remote filling device 13,21,29 of the invention is fitted to the upper part of the tank 2, close to the desired maximum oil level N1 in the tank space. 
     A preferred embodiment of the filling device of the invention is shown in FIG. 2. The device comprises an inlet nozzle 16 and an overflow outlet nozzle 24 which are open to the tank space and are interconnected by a locking device 29. The inlet nozzle 16 is situated above the outlet nozzle 24, the axes of the two nozzles being horizontal. 
     The inlet nozzle 16 has a threaded end 16a for the connection of an oil supply pipe 14. The supply pipe 14 has a coupling sleeve 14a which is arranged to be screwed onto the threaded end 16a of the inlet nozzle 16, and the supply pipe 14 is thus detachable from the nozzle 16. 
     An inlet slide valve 18 is slidably mounted inside the inlet nozzle 16. The slide valve 18 is of a cylindrical shape and has, at an end thereof adjacent the threaded end 16a of the inlet nozzle 16, a portion 18a of smaller diameter forming a shoulder which normally acts through a seal 18d on a complementary shoulder formed inside the nozzle 16 under the action of a compression spring 20. This spring 20 is enclosed between the end 18b of the inlet slide valve 18 opposite its end 18a and a support member 17 fixed on the inlet nozzle 16. 
     A passage 19 is formed through the slide valve 18 between the end 18b and a portion of its periphery positioned rearwardly from the seal 18d relative to the end 18a of the valve. The spring 20 normally urges the slide valve 18 to a closed position in which the passage 19 does not communicate with the opening through the threaded end 16a of the inlet nozzle 16. However, when the supply pipe 14 is connected to the nozzle 16 by the sleeve 14a, a protruding part 14b at the end of the supply pipe 14 pushes the slide valve 18 back against the action of the spring 20, and the passage 19 then communicates with the opening through the threaded end of the inlet nozzle 16 to permit the flow of oil into the tank 2. 
     The inlet slide valve 18 also has a notch 18c formed by a peripheral annular groove around its mid portion. 
     In addition, the inlet slide valve 18 has a transverse passage 18e which normally (i.e. when the slide valve 18 is in the closed position) ensures the flow of air between the inside of the tank 2 and the degassing pipe 10, the latter being connected to a degassing system which is not shown in the drawing. In the open position of the slide valve 18, i.e. when remote filling of the tank 2 is taking place, the transverse passage 18e is displaced towards the support member 17 so that air is prevented from flowing through the passage 18e to the degassing pipe 10. Since this air passage is then blocked, in the unlikely event of overfilling the tank, oil could not escape along the degassing pipe 10 to cause the effects mentioned earlier. In addition, since the ability of air to escape during filling is reduced, the return of oil through the overflow pipe is effected at higher speed. 
     In a manner similar to that of the inlet nozzle 16, the outlet nozzle 24 has a threaded end 24a for the connection of a removal pipe 22 for the overflow oil. This removal pipe 22 is detachable, having a coupling sleeve 22a at its end which is arranged to be screwed on the threaded end 24a of the outlet nozzle 24. 
     An outlet slide valve 26 is slidably mounted inside the outlet nozzle 24. This outlet slide valve 26 is of a cylindrical shape and has, at its end adjacent the threaded end 24a of the outlet nozzle 24, a portion 26a of smaller diameter forming a shoulder which normally acts through a seal 26d on a complementary shoulder formed inside the nozzle 24 under the action of a compression spring 28. This spring 28 is enclosed between the end 26b of the outlet slide valve 26 opposite its end 26a and a support member 25 fixed to the outlet nozzle 24. 
     A passage 27 is formed through the slide valve 26 between its end 26b and a portion of its periphery situated rearwardly from the seal 26d relative to the end 26a of the valve. The spring 28 normally urges the slide valve 26 to a closed position, in which the passage 27 does not communicate with the opening through the threaded end 24a of the outlet nozzle 24. However, when the removal pipe 22 is connected to the nozzle 24 by the sleeve 22a, a protruding part 22b of the end of the removal pipe 22 pushes the slide valve 26 back against the action of the spring 28, and the passage 27 then communicates with the opening through the threaded end 24a of the outlet nozzle to permit the overflow of oil from the tank 2. 
     The outlet slide valve 26 is provided with a peripheral annular cam surface 26c at is mid portion. 
     The locking device 29 comprises a locking member 30 which is slidably mounted transversely to the axes of the inlet and outlet nozzles 16,24 and which interacts with the slide valves 18 and 26 in a manner dependent on their positions. 
     The locking member 30 is in the form of a cylindrical peg having three adjacent parts of different diameters: a first part 30a forming a stem which bears on the cam surface 26a of the outlet slide valve 26; a second part 30b in the form of a circular plate overhanging the first part 30a; and a third part 30c which has a diameter intermediate that of the first part 30a and that of the second part 30b, and which is able to fit into the notch 18c in the side of the inlet slide valve 18. A compression spring 32 is positioned around the third part 30c of the locking member 30, and acts between the second part 30b and the inlet nozzle 16 to ensure that the first part 30a of the locking member bears on the cam surface 26c of the outlet slide valve 26. 
     When the outlet slide valve 26 moves to its open position, the first part 30a of the locking member 30 moves into contact with the part of the cam surface 26c of least diameter, and the third part 30c of the locking member 30 thus moves clear of the notch 18c in the inlet slide valve 18. 
     FIGS. 3A,3B and 3C show the three main operative positions which the device may occupy. 
     FIG. 3A shows the device in its normal or rest state, i.e. when remote filling is not taking place. In this state the compression springs 20 and 28 are in the expanded position and both the inlet and the outlet slide valves 18 and 26 are in the closed position. The first part 30a of the locking member 30 thus bears on the part of the cam surface 26c of greater diameter, and the third part 30c of the locking member 30 is engaged in the notch 18c of the inlet slide valve 18. The inlet slide valve 18 is thus locked in the closed position, and connection with the supply pipe 14 is impossible. Also, the transverse passage 18e is open to ensure the flow of air to the degassing pipe 10. 
     FIG. 3B shows the device when the removal pipe 22 has been connected to the outlet nozzle 24. The connection of the pipe 22 results in the movement of the outlet slide valve 26 to its open position, thus compressing the spring 28. When the slide valve 26 moves from the closed position to the open position, the first part 30a of the locking member 30 slides over the cam surface 26c and into the part of least diameter, thus retracting the third part 30 c of the locking member 30 out of the notch 18c of the inlet slide valve 18. The inlet slide valve 18 is thus unlocked. 
     FIG. 3C shows the device when both the supply and removal pipes 14 and 22 are connected to their respective nozzles 16 and 24. When the removal pipe 22 is connected and the inlet slide valve 18 is unlocked as explained above, the connection of the supply pipe 14 may be effected without any problems. The result of this connection is the pushing of the inlet slide valve 18 into its open position, thus compressing the spring 20 and shutting off the transverse passage 18e. Oil is then free to flow into the tank in order to fill the tank, and any overflow is able to flow out through the outlet nozzle and removal pipe 22. Furthermore, in the event of an oil overfill, the oil is prevented from flowing out through the degassing duct 10. 
     It will be clear from these last three figures that the connection of the supply pipe 14 is impossible as long as the inlet slide valve 18 is locked in the closed position, that is to say as long as the outlet slide valve 26 is closed and the locking member 30 is maintained in engagement with the notch 18c by the cam surface 26.