Sealing arrangement for relatively movable parts and device including such a sealing arrangement

Abstract

A sealing arrangement for two relatively movable first and second parts and including a sealing ring positioned in a groove on one of the parts for sealing contact against the other one of the parts, so as to separate a first side of the sealing ring from a second side of the sealing ring, wherein the sealing ring is positioned in a sealing ring seat formed as a groove in the circumference of one of the parts, including liquid supply means for supplying liquid under pressure to the second side of the sealing ring, and means for balancing the pressure of the supplied liquid in the region of the sealing ring, whereby forces on the sealing ring resulting from the pressure prevailing on the first side of the sealing ring are counteracted and balanced in such a way that in operation the sealing ring is essentially free-floating in the groove. The invention also concerns a reciprocating piston device including such a sealing arrangement.

1 . A sealing arrangement for two relatively movable first and second parts, said sealing arrangement including a sealing ring positioned in a sealing ring seat formed as a groove in a circumference of one of the parts for sealing contact against the other one of the parts, so as to separate a first side of the sealing ring from a second side of the sealing ring, said sealing arrangement comprising:
 liquid supply means for supplying liquid under pressure to the second side of the sealing ring, and   means for balancing a pressure of the supplied liquid in a region of the sealing ring so that forces on the sealing ring resulting from the pressure prevailing on the first side of the sealing ring are counteracted and balanced in such a way that in operation the sealing ring is essentially free-floating in the groove,   the first and second parts being relatively rotatable.   
     
     
         2 . The arrangement according to  claim 1 , further comprising a valve device set to balance the pressure of the supplied liquid in the area of the sealing ring. 
     
     
         3 . The arrangement according to  claim 2 , wherein the valve device is preset to limit the pressure of the supplied liquid. 
     
     
         4 . The arrangement according to  claim 3 , wherein the valve device is set to limit the pressure between 80 and 100% of the pressure inside the pressure chamber. 
     
     
         5 . The arrangement according to  claim 2 , wherein the valve device includes a portion of the sealing ring in co-operation with the sealing ring seat. 
     
     
         6 . The arrangement according to  claim 5 , wherein said portion of the sealing ring is a ring surface directed from the first side which is arranged to co-operate with a surface of said seat. 
     
     
         7 . The arrangement according to  claim 5 , wherein said portion of the sealing ring is an edge portion or a separate sealing element directed radially from the element said portion is intended to seal against. 
     
     
         8 . The arrangement according to  claim 3 , wherein the valve device is a pressure controlled valve which is separate from the sealing ring. 
     
     
         9 . The arrangement according to  claim 1 , further comprising a sealing device for sealing between the relatively movable parts in a position opposite to the sealing ring as seen from the position of the means for liquid supply. 
     
     
         10 . The arrangement according to  claim 9 , wherein said sealing device is formed by a first, high pressure seal member and a second, low pressure seal, and an intermediate space having a fluid outlet. 
     
     
         11 . The arrangement according to  claim 10 , wherein the fluid outlet is a low pressure outlet for eliminating pressure build-up in the intermediate space. 
     
     
         12 . The arrangement according to  claim 1 , wherein at least one of the parts includes at least one outlet channel for supplied liquid. 
     
     
         13 . A rotatable shaft device including a shaft being rotatable inside an opening in a housing and a sealing ring which is positioned in a seat formed as a groove in the circumference of one of the shaft and the housing for sealing contact between the shaft and the housing, so as to separate a first side of the sealing ring from a second side of the sealing ring, said shaft and housing forming a pressure chamber, said rotatable shaft device comprising:
 liquid supply means for supplying liquid under pressure to the second side of the sealing ring, and   means for balancing a pressure of the supplied liquid in a region of the sealing ring, so that forces on the sealing ring resulting from the pressure prevailing on the first side of the sealing ring are counteracted and balanced in such a way that in operation the sealing ring is essentially free-floating in the groove.   
     
     
         14 . The device according to  claim 13 , wherein the liquid supply means includes an external pump having at least one supply conduit debouching in a wall of the second part. 
     
     
         15 . The device according to  claim 15 , wherein the liquid supply means includes a liquid pump selected from the group of a gear type pump, a reciprocating piston pump, an impeller pump, a screw pump or a rotary piston pump. 
     
     
         16 . The device according to  claim 13 , wherein the shaft includes a valve device which is preset to balance the liquid pressure in the area of the sealing ring. 
     
     
         17 . The device according to  claim 16 , wherein the valve device is set to limit the pressure to between 80 and 100% of the pressure inside the pressure chamber. 
     
     
         18 . The device according to  claim 16 , wherein the valve device includes a portion of the sealing ring in co-operation with its seat. 
     
     
         19 . The device according to  claim 18 , wherein said portion of the sealing ring is a ring surface directed from the pressure chamber which is arranged to co-operate with a surface of said seat. 
     
     
         20 . The device according to  claim 18 , wherein said portion of the sealing ring is an edge portion directed radially from the element said portion is intended to seal against. 
     
     
         21 . The device according to  claim 13 , wherein the shaft includes at least one outlet channel for liquid. 
     
     
         22 . The device according to  claim 13 , wherein the valve device is a pressure controlled valve which is separate from the sealing ring. 
     
     
         23 . The device according to  claim 13 , further comprising a sealing device for sealing between the shaft and the housing in a position opposite to the sealing ring as seen from the position of liquid supply means. 
     
     
         24 . The device according to  claim 23 , wherein said sealing device is formed by a first, high pressure seal member and a second, low pressure seal, and an intermediate space having a fluid outlet.