| 摘要 |
A fuel pump for an engine may include a cylinder, a piston displaceably disposed in the cylinder, and a cam driven by the engine. The cam engages the piston to form a cam-follower mechanism so that the rotation of the cam generates a reciprocal movement of the piston inside the cylinder. The cam preferably includes a variable cam lobe having a maximum radius that is a function of engine speed so that the displacement of the piston generated by the variable cam lobe is a function of the engine speed. The cam may also include a weight that is subject to a centrifugal force when the ram is rotating. Alternatively, the maximum radius of the variable cam lobe may be a function of pump outlet pressure so that the displacement of the piston generated by the variable cam lobe is a function of the pump outlet pressure.
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