Patent ID: 7789635
Filing Date: 2010-09-07
Classification: F02M,F04B

Abstract:
1. A piston/cylinder unit for a high pressure pump, comprising: a housing defining a pump cylinder; a piston arranged in said pump cylinder and having a first end defining a head region of said piston and a second end opposing said first end; a controlled drive acting on said second end of said piston configured to oscillate said piston in said cylinder through a suction stroke and a compression stroke; a conveying flow inlet connected to said cylinder; and a conveying valve, wherein a fluid is drawn into said cylinder through said conveying flow inlet during the suction stroke and a pressure of the fluid in said cylinder is increased during the compression stroke for feeding the fluid through said conveying valve, and wherein said piston comprises a first centering cone at said head region comprising a truncated cone having a circular base area and a top area, wherein a ratio of a maximum half diameter reduction of said first centering cone with respect to the diameter of said piston is approximately 1:200 and a ratio of the axial length of said first centering cone to the length of said piston is approximately 1:6.6 and a bevel comprising a second centering cone positioned on said first centering cone, wherein a distance between a center axis of said first centering cone and a center axis of said second centering cone has a maximum tolerance of 1 μm.