Importance

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Abstract

A novel fuel pump arrangement comprises cam driven low and high pressure reciprocating plunger pump units. The fuel pump has rotary drive means, a high pressure pump with a pump body which defines a pumping chamber with an annular arrangement of a plurality of pairs of bores extending radially outwardly from a cam axis. A pumping plunger is mounted in each pumping plunger bore for reciprocation. The fuel pump also comprises a single transfer pump for transferring fuel under pressure to the pumping plunger bores of the pumping chamber. This transfer pump includes a single transfer plunger mounted within a transfer plunger bore for reciprocation to provide alternating intake and transfer phases of operation of the transfer pump. The fuel pump further includes an annular cam ring surrounding the high pressure pump body such that the cam ring is rotatable about the cam axis by the rotary drive to thereby cause reciprocation of the transfer plunger in predetermined synchronization with the high pressure pump whereby fuel is intermittently transferred into the high pressure pump during the intake phase of the high pressure pump and the transfer phase of the transfer pump.

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First Claim