| 摘要 |
834,710. Pistons. S.U. CARBURETTOR CO. Ltd. Aug. 18, 1958 [Sept. 4, 1957], No. 27882/57. Class 122 (1). [Also in Group XXVIII] A fuel injection pump (see Group XXVIII) comprises a smaller diameter piston 8 and a large diameter piston 9 urged into contact by spring 13. The piston 8 normally contacts the piston 9 on an abutment 14, of smaller area than the piston 8, from which extends a passage 21. In operation the pistons move downwards and piston 9 uncovers the inlet groove 15 at the same time as passage 17 on the piston 8 moves clear of the cylinder 6, fuel then flows into the chamber 19 and through passages 17, 16 to the pumping chamber 18. On the upward stroke of the pistons fuel is discharged through an outlet valve 22 by the piston 8 and the pressure in the chamber 19 rises until it acts on the lower end of piston 8 to separate the pistons, this causes the piston 8 to open the passage 21 and fuel in the chamber 19 is bypassed to the inlet. Such an arrangement ensures that the pressure in chamber 19 varies with that in the pumping chamber 18 while remaining slightly above this latter pressure and thus prevents leakage of fuel from the chamber 18 past the piston 8. |
