Automatic Shut-Off Valve For The Oil Circuit In An Airplane Engine

Abstract

The present invention concerns a lubrication system in a closed circuit provided with a valve comprising a first position and a second position, as well as an IN inlet, a first BP outlet and a second M outlet, said IN inlet being connected to the outlet of the feed pump, the first BP outlet being connected to the bypass circuit and the second M outlet being connected to the feed circuit. In the first position of the valve, the flow entering via the IN inlet is diverted to the first BP outlet and in the second position, the incoming flow is diverted to the second M outlet, said valve switching from the first position to the second position and vice versa, when the incoming flow rate exceeds a predetermined threshold upwards and downwards respectively.

1 . A lubrication system in a closed circuit comprising:
 a feed pump ( 17 );   an oil tank ( 16 );   a feed circuit ( 19 ) supplying the oil to housings ( 20 ) containing parts to be lubricated;   a collection circuit ( 21 ) returning the oil from the housings ( 20 ) to the tank ( 16 );   a bypass circuit ( 18 ) returning the oil from the outlet of the feed pump ( 17 ) to the tank ( 16 ) or to the inlet of the feed pump ( 17 );   a valve ( 22 ) comprising a first position and a second position as well as an IN inlet ( 1 ), a first BP outlet ( 3 ) and a second M outlet ( 2 ), said IN inlet ( 1 ) being connected to the outlet from the feed pump ( 17 ), the first BP outlet ( 3 ) being connected to the bypass circuit ( 18 ) and the second M outlet ( 2 ) being connected to the feed circuit ( 19 );   
     characterized in that, in the first position, the flow entering via the IN inlet ( 1 ) is diverted to the first BP outlet ( 3 ) and, in the second position, the incoming flow is diverted to the second M outlet ( 2 ), said valve switching from the first position to the second position and vice versa, when the incoming flow exceeds a predetermined threshold upwards and downwards respectively. 
   
   
       2 . Lubrication system as in  claim 1 , characterized in that said valve ( 22 ) comprises a valve ( 4 ) which slides slightly loose in a bore ( 7 ) machined into a valve body ( 6 ) between two opposite seats ( 10 ,  11 ), a first seat ( 10 ) being connected to the IN inlet ( 1 ) and a second seat ( 11 ) being connected to the BP outlet ( 3 ), the M outlet ( 2 ) emerging in the bore ( 7 ) in a ring-shaped cavity ( 8 ) surrounding the first seat ( 10 ), so that:
 a. for a flow rate in the IN inlet ( 1 ) lower than the predetermined threshold, the valve ( 4 ) is pushed by a spring ( 5 ) on the first seat ( 10 ) controlling the IN inlet ( 1 ) and the connection from the IN inlet ( 1 ) to the ring-shaped cavity ( 8 ) is blocked, the connection being opened towards the BP outlet ( 3 ) via at least one calibrated opening ( 9 ) passing through the valve ( 4 ) and emerging laterally in the bore ( 7 ) upstream from the seat ( 11 ) of the BP outlet ( 3 );   b. for a flow rate from the IN inlet ( 1 ) greater than or equal to the predetermined threshold, the valve ( 4 ) moves to the second seat ( 11 ) in a position where it rests against the second seat ( 11 ), closing the BP outlet ( 3 ) and where the IN inlet ( 1 ) is connected to the M outlet ( 2 ) via the ring-shaped cavity ( 8 ), the first seat ( 10 ) being released by the movement of the valve ( 4 ).   
   
   
       3 . Lubrication system as in  claim 2 , characterized in that the valve ( 4 ) is made of at least two parts which push against each other. 
   
   
       4 . Lubrication system as in  claim 2 , characterized in that the seal of any outlet or of the two outlets of the valve ( 22 ) is provided by means of a cover principle of the “sliding type” ( 13 ) replacing the seat-valve contact. 
   
   
       5 . Lubrication system as in  claim 1 , characterized in that said valve ( 22 ) comprises a valve ( 4 ) which slides in a bore ( 7 ) between two opposite seats ( 23 ,  24 ), a first seat ( 23 ) being connected to the M outlet ( 2 ) and a second seat ( 24 ) being connected to the BP outlet ( 3 ), the IN inlet ( 1 ) emerging in the bore ( 7 ) in a ring-shaped cavity surrounding the first seat ( 23 ) and the bore ( 7 ) or the valve ( 4 ) comprising at least one calibrated channel ( 15 ) between the two seats ( 23 ,  24 ), the parts of said valve ( 22 ) being proportioned in such a way that:
 c. for a flow rate from the IN inlet ( 1 ) lower than the predetermined threshold, a spring ( 5 ) holds said valve ( 4 ) rested against the first seat ( 23 ), closing the M outlet ( 2 ), the flow being diverted towards the BP outlet ( 3 );   d. for a flow rate from the IN inlet ( 1 ) greater than or equal to the predetermined threshold, said valve ( 4 ) moves to the second seat ( 24 ), opening the M outlet ( 2 ) and closing the BP outlet ( 3 ).   
   
   
       6 . Lubrication system as in  claim 5 , characterized in that the valve ( 4 ) is spherical. 
   
   
       7 . Aircraft engine comprising a lubrication system as in  claim 1 . 
   
   
       8 . Aircraft engine as in  claim 7 , characterized in that it is a turbojet, a turboprop, a turboshaft or a helicopter engine. 
   
   
       9 . Aircraft engine as in  claim 7 , characterized in that said lubrication system and said valve ( 22 ) are located in one casing.