Fluid pump assembly

Abstract

A fluid pump assembly includes a double acting fluid cylinder with a housing, a piston reciprocally disposed within the housing, and a piston rod carrying the piston and extending from the housing. The piston rod has an end. A pump includes a pump body, a pressure loaded seal and a wiper seal. The pump body has a fluid inlet, a pump chamber and a rod port. The inlet is configured for receiving a fluid to be pumped and is in fluid communication with the pump chamber. The piston rod extends through the rod port and the end is positioned within the pump chamber. The pressure loaded seal is positioned within the rod port around the piston rod and has a pressure loaded end face toward the pump chamber. The wiper seal is positioned within the rod port around the piston rod on a side of the pressure loaded seal opposite from the pump chamber. The pump body further has a scavenging groove in an area between the pressure loaded seal and the wiper seal. The scavenging groove is in fluid communication with the inlet, whereby any fluid which leaks past the pressure loaded seal is returned to the inlet.

1 . A fluid pump assembly, comprising:
 a double acting fluid cylinder including a housing, a piston reciprocally disposed within said housing, and a piston rod carrying said piston and extending from said housing, said piston rod having an end; and   a pump including a pump body, a pressure loaded seal and a wiper seal, said pump body having a fluid inlet, a pump chamber and a rod port, said inlet being configured for receiving a fluid to be pumped and being in fluid communication with said pump chamber, said piston rod extending through said rod port and said end positioned within said pump chamber, said pressure loaded seal positioned within said rod port around said piston rod and having a pressure loaded end face toward said pump chamber, said wiper seal positioned within said rod port around said piston rod on a side of said pressure loaded seal opposite from said pump chamber, said pump body further having a scavenging groove in an area associated with said pressure loaded seal and said wiper seal, said scavenging groove being in fluid communication with said inlet, whereby any fluid which leaks past said pressure loaded seal is returned to said inlet.   
     
     
         2 . The fluid pump assembly of  claim 1 , wherein said scavenging groove is an annular groove surrounding said piston rod. 
     
     
         3 . The fluid pump assembly of  claim 2 , wherein said scavenging groove is located on a side of said wiper seal opposite from said pressure loaded seal. 
     
     
         4 . The fluid pump assembly of  claim 1 , wherein said fluid cylinder is an air cylinder. 
     
     
         5 . A fluid pump assembly, comprising:
 a double acting fluid cylinder including a housing, a piston reciprocally disposed within said housing, and a piston rod carrying said piston and extending from opposite ends of said housing, said piston rod having a first end and a second end;   a first pump including a pump body, a fluid inlet, a pressure loaded seal and a wiper seal, said pump body having a pump chamber and a rod port, said piston rod extending through said rod port and said first end positioned within said pump chamber, said pressure loaded seal positioned within said rod port around said piston rod and having a pressure loaded end face toward said pump chamber, said wiper seal positioned within said rod port around said piston rod on a side of said pressure loaded seal opposite from said pump chamber; and   a second pump including a pump body, a fluid inlet, a pressure loaded seal and a wiper seal, said pump body having a pump chamber and a rod port, said piston rod extending through said rod port and said second end positioned within said pump chamber, said pressure loaded seal positioned within said rod port around said piston rod and having a pressure loaded end face toward said pump chamber, said wiper seal positioned within said rod port around said piston rod on a side of said pressure loaded seal opposite from said pump chamber;   wherein at least one of said first pump and said second pump include a fluid scavenging arrangement, said fluid scavenging arrangement having a scavenging groove in an area associated with a corresponding said pressure loaded seal and said wiper seal, said scavenging groove being in fluid communication with a corresponding fluid inlet, whereby any fluid which leaks past said pressure loaded seal is returned to said corresponding inlet.   
     
     
         6 . The fluid pump assembly of  claim 5 , wherein said scavenging groove is an annular groove surrounding said piston rod. 
     
     
         7 . The fluid pump assembly of  claim 6 , wherein said scavenging groove is located on a side of a corresponding said wiper seal opposite from said pressure loaded seal. 
     
     
         8 . The fluid pump assembly of  claim 5 , wherein said fluid cylinder is an air cylinder.