External Gear Pump

Abstract

An external gear pump capable of achieving both a sealing property and a sliding property is disclosed. The external gear pump includes a pair of rotating shafts that are respectively pivotally supported by bearings provided in a casing; at least a pair of gears that are respectively fixed to the pair of rotating shafts and are externally meshed with each other; a side plate that is provided in sliding contact with one side surfaces of the pair of gears; and a seal block integrally including a side surface sliding part and a tooth tip sliding part. The external gear pump further includes movement restrictors on both sides of a straight line connecting axes of the pair of gears, and the movement restrictors restrict the seal block from moving with respect to the casing on a plane orthogonal to the rotating shafts.

1 . An external gear pump comprising:
 a casing;   a pair of rotating shafts that are respectively pivotally supported by bearings provided in the casing;   at least a pair of gears that are respectively fixed to the pair of rotating shafts and are externally meshed with each other;   a side plate that is provided in sliding contact with one side surfaces of the pair of gears; and   a seal block integrally including:
 a side surface sliding part that slidingly contacts another side surfaces of the pair of gears; and 
 a tooth tip sliding part that seals tooth tips of the gears, wherein: 
   the external gear pump further comprises movement restrictors on both sides of a straight line connecting axes of the pair of gears; and   the movement restrictors restrict the seal block from moving with respect to the casing on a plane orthogonal to the rotating shafts.   
     
     
         2 . The external gear pump according to  claim 1 , wherein:
 at least one of the movement restrictors restricts the seal block from moving in a direction substantially parallel to the straight line connecting the pair of gears, on the plane orthogonal to the rotating shafts; and   at least another one of the movement restrictors restricts the seal block from moving in both of a direction substantially orthogonal to and the direction substantially parallel to the straight line connecting the pair of gears, on the plane orthogonal to the rotating shafts.   
     
     
         3 . The external gear pump according to  claim 1 , wherein:
 at least one of the movement restrictors restricts the seal block from moving in a direction substantially parallel to the straight line connecting the pair of gears, on the plane orthogonal to the rotating shafts; and   at least another one of the movement restrictors restricts the seal block from moving in a direction that is substantially orthogonal to the straight line connecting the pair of gears and is toward the pair of gears from the tooth tip sliding part, on the plane orthogonal to the rotating shafts.   
     
     
         4 . The external gear pump according to  claim 1 , wherein
 at least one of the movement restrictors is a pin.   
     
     
         5 . The external gear pump according to  claim 1 , wherein
 the seal block is made of a resin.   
     
     
         6 . The external gear pump according to  claim 1 , further comprising a sealing member on a surface of the seal block, the surface being in contact with the casing, wherein
 an area of a portion of the surface in contact with the casing is smaller than a high-pressure applied area on an opposite side of the seal block, the portion being surrounded by the sealing member and receiving a high pressure.   
     
     
         7 . The external gear pump according to  claim 6 , wherein
 the sealing member is provided in a circular pattern on the surface of the seal block, the surface being in contact with the casing.