Patent ID: 7544051
Filing Date: 2009-06-09
Classification: F02M

Abstract:
1. A pump for pumping fluid comprising: a ring cam having a central axis, configured to rotate about an axis of rotation coincident with the central axis, and surrounding a pump head having a major axis, said pump head defining two parallel plunger boars extending therethrough, said plunger boars arranged on opposing sides of the major axis, separated from the major axis by an offset, each having the same off-set from the major axis, and having a common bore axis plane substantially transverse to the central axis, each plunger boar having a pair of plungers, each pair of plungers comprising a first plunger and a second plunger, each plunger being reciprocable within a respective plunger bore defined by a housing, the respective plunger bores being in communication with one another by way of a connecting passage, wherein each pair of first and second plungers, together with their respective plunger bores, defines, at least in part, a pumping volume, each pair of plungers performing, in use, a pumping cycle, and each pair of plungers having a respective inlet port and outlet port, wherein an end of each said first plunger is arranged to cover its respective inlet port during a pump delivery stage in which fluid is displaced from the pumping volume, wherein an end of each said second plunger is arranged to cover its respective outlet port during a pump fill stage in which fuel is drawn into the pumping volume, wherein the end of each said first plunger and the end of each said second plunger are arranged to cover the inlet port and outlet port respectively during a pump transfer stage during which the pumping volume is maintained, wherein each pair of first and second plungers are aligned along a respective common bore axis, and each said pair of first and second plungers mounted in opposed in-line formation within said pump head, and wherein each plunger is coupled to a shoe that embraces a respective roller that is in contact with, and is thus driven by the ring cam.