Improvements in self-regulating reciprocating action pumps, and in particular in fuel injection pumps, for internal combustion engines

摘要

835,344. Fuel injection pumps. BESSIERE, P. E. Dec. 10, 1957 [Dec. 13, 1956], No. 38394/57. Class 102(1). In a reciprocating pump a by-pass conduit is open by a valve member at the commencement of the discharge stroke, the valve being braked in its movement to close this by-pass conduit. A valve 12 is moved by liquid supplied under pressure through conduit 4, passage 17, groove 18 in the pump piston 1, past non-return valve 17a to chamber 13a, against the action of a spring 16 to open the by-pass conduit 11 when the piston 1 is in its lower dead centre position, this liquid also fills the pumping chamber 5 through conduit 3. As the piston 1 moves on its discharge stroke it first closes conduit 17 then conduit 3 and through groove 24 opens the interruption in a relief conduit 23, liquid in the chamber 13a is then free to flow past throttle 20, through conduits 10 and 23 to drain thus allowing the valve 12 to move downwards. When the portion 12a of the valve is about to close the by-pass conduit 11 the chamber 13a is connected to conduit 21 via a passage 22 in the valve portion 12b thus allowing a sudden closing of the by-pass 11 at which time liquid in the chamber 5 passes to the delivery line 7. Since the time of closing of the by-pass 11 is constant for a setting of the throttle 20, as the speed of the piston 2 increases more liquid will be by-passed on each stroke of the piston. In order to ensure a full movement of the valve 12 by the liquid pressure a throttle 25 is inserted in the feed conduit 3 to the pumping chamber. Delivery is ended when a passage 9 in the piston by-passes the liquid through conduit 10. The throttle 25 may be replaced by a passage in the plunger which allows communication between the feed conduit 3 and the pumping chamber 5 before the piston 1 reaches its lower dead centre position, and closes this communication before opening the conduit 17. A separate pump may be used to supply liquid to move the valve 12 and this pump may also feed the liquid to the chamber 5. In this case the second pump is 180 degrees out of phase with the first pump.