Patent ID: 7300267

Claim:
In a pump unit for pumping fuel to an internal combustion engine, having a rotor supported eccentrically in a pump chamber, a plurality of guide grooves disposed on the rotor circumference, and sealing bodies disposed in the grooves that are guided in the radial direction along a shaped sliding surface in the pump chamber, the shaped sliding surface having elliptical portions, the improvement wherein the course, expressed in polar coordinates (φ), of the radii (ρ) of the elliptical portions corresponds at least in portions to one of the two following equations, in which (R 2 ) is the radius of the rotor, n is a variable power, and (s 1 ) is the eccentricity: ρ ⁢ ( φ ) = R 2 * R 2 + 2 ⁢ s 1 R 2 n / 2 * (  cos ⁢ ( φ + π 2 )  ) n + ( R 2 + 2 ⁢ s 1 ) n / 2 * (  sin ⁢ ( φ + π 2 )  ) n n ρ ⁢ ( φ ) = R 2 * ( R 2 + 2 ⁢ s 1 ) R 2 n / 2 * (  cos ⁢ ( φ )  ) n + ( R 2 + 2 ⁢ s 1 ) n / 2 * (  sin ⁢ ( φ )  ) n n