Vane pump having a pressure plate and a shaft seal

A vane pump for pumping a liquid or gaseous medium, the pump comprising:

• a casing, an operating chamber in the casing, the operating chamber having opposite first and second axial sides;
• a rotatable rotor in the casing, a drive shaft connected with the rotor for rotating the rotor;
• pump vanes in the operating chamber and the vanes being attached to the rotor to rotate with the rotor;
• the vanes being radially moveable in the operating chamber of the pump as the rotor rotates;
• a pressure plate positioned at the first axial side of the operating chamber, the pressure plate having an axially inward lateral face toward the operating chamber for closing the operating chamber at the first axial side;
• the pressure plate having an axially outward lateral face facing away from the operating chamber and away from the rotor in the operating chamber;
• a through opening in the pressure plate through which the drive shaft extends;
• the casing including a pressure chamber communicating with the axially outward lateral face of the pressure plate;
• a pump connection from an external source of a medium past the operating chamber and the vanes and to the pressure chamber, whereby the pressure chamber is supplied with medium under pressure by rotation of the rotor and operation of the vanes;
• a coupling element including a first portion thereof which surrounds a portion of the drive shaft axially at the pressure chamber;
• a shaft seal around the drive shaft, axially outward of the pressure plate and the coupling element and the shaft seal being shaped and positioned to seal the pressure chamber with respect to the drive shaft;
• the coupling element having a first sleeve section which extends into the through opening in the pressure plate and engages the pressure plate in the through opening in the pressure plate;
• said shaft seal comprising a shaft seal ring around the shaft, the shaft seal ring having a radial exterior of an external diameter and having a radial interior engaging the shaft;
• the shaft seal ring is axially outward of the pressure plate;
• the diameter of the through opening in the pressure plate is smaller than the external diameter of the shaft seal ring;
• the casing having a section shaped for engaging and which accommodates the radial exterior of the shaft seal ring;
• and the coupling element including a second collar that engages at least partially over the section of the casing which accommodates the shaft seal ring.