Pumps

A pump comprising,

• a first fluid port and a second fluid port,
• a housing having an interior surface defining a cavity in which a rotor is located,
• a rotor, being rotatably mounted within the housing and having a longitudinal axis of rotation, and comprising, a housing engaging surface area forming a sealing interference fit with the interior surface of the housing, and a surface recess that forms with said interior surface of the housing a fluid-conveying chamber that, on rotation of the rotor, conveys fluid from the first fluid port to the second fluid port, the rotor being twisted about the longitudinal axis of rotation thereof, such that a first end and a second end of the rotor are rotationally off-set relative to one another by at least 10 degrees,
• a resiliently deformable diaphragm providing part of the interior surface of the housing, the diaphragm comprising a rotor engaging surface and a rear surface opposite the rotor engaging surface, the rotor engaging surface of the diaphragm being urged into contact with the rotor by a pressurizing means acting on the rear surface of the diaphragm,
• the rotor comprising an elongate body and a drive shaft, which body is substantially hollow and comprises separate first and second rotor cavities, the first rotor cavity having an opening at a first end of the rotor and the second rotor cavity having an opening at a second end of the rotor, the rotor further comprising a first opening between the first rotor cavity and the surface recess and a second opening between the surface recess and the second rotor cavity,
• the pump being arranged such that when the rotor is located within the cavity in the housing, the first fluid port is in fluid flow communication with the first rotor cavity via the opening at the first end of the rotor, and the second fluid port is in fluid flow communication with the second rotor cavity via the opening at the second end of the rotor, and
• the pump being arranged such that the resiliently deformable diaphragm always bisects the first opening and the second opening on the rotor surface recess as the rotor rotates.

A pump comprising,

• a first fluid port and a second fluid port,
• a housing having an interior surface defining a cavity in which a rotor is located,
• a rotor, being rotatably mounted within the housing and having a longitudinal axis of rotation, and comprising, a housing engaging surface area forming a sealing interference fit with the interior surface of the housing, and a surface recess that forms with said interior surface of the housing a fluid-conveying chamber that, on rotation of the rotor, conveys fluid from the first fluid port to the second fluid port,
• a resiliently deformable diaphragm providing part of the interior surface of the housing, the diaphragm comprising a rotor engaging surface and a rear surface opposite the rotor engaging surface, the rotor engaging surface of the diaphragm being urged into contact with the rotor by a pressurizing means acting on the rear surface of the diaphragm, a linear rib either upstanding from either the rear surface of the resiliently deformable diaphragm or acting on the rear surface of the diaphragm, the linear rib being angled relative to the longitudinal axis of rotation of the rotor by at least 10 degrees,
• the rotor comprising an elongate body and a drive shaft, which body is substantially hollow and comprises separate first and second rotor cavities, the first rotor cavity having an opening at a first end of the rotor and the second rotor cavity having an opening at a second end of the rotor, the rotor further comprising a first opening between the first rotor cavity and the surface recess and a second opening between the surface recess and the second rotor cavity,
• the pump being arranged such that when the rotor is located within the cavity in the housing, the first fluid port is in fluid flow communication with the first rotor cavity via the opening at the first end of the rotor, and the second fluid port is in fluid flow communication with the second rotor cavity via the opening at the second end of the rotor, and
• the pump being arranged such that the resiliently deformable diaphragm always bisects the first opening and the second opening on the rotor surface recess as the rotor rotates.