| 摘要 |
<p>A supply pump comprising a body having an inlet and an outlet both in fluid communication with an interior region of the body which contains two pistons positioned to reciprocate coaxially and which define three variable volume chambers, one between the two pistons and in fluid communication with the inlet, a second between one piston and the outlet and a third between the other piston and the outlet. The pistons have different working areas, and the piston of larger area carries a check valve which allows fluid flow from the chamber between the pistons to the chamber between the larger piston and the outlet. A regulating spring acts between the body and the smaller piston to urge both pistons against a mechanical drive means including a reciprocable rod carried by a tappet contacting a driven cam. During each forward and reverse stroke of the pistons in response to rotation of the cam, supply fluid is drawn into the pump through the inlet and forced out of the pump through the outlet.</p> |
