Patent GB-490547-A (GB)
Title: Improvements in or relating to the regulation of fuel injection pumps
IPC: F16J15/32
Filed: 1937-02-19
Abstract: 490,547. Fuel-injection pumps. PRECISION MECANIQUE. Feb. 19, 1937, No. 5088. Convention date, Feb. 19, 1936. [Class 102 (i)] A fuel-injection pump comprises a piston 21a actuated mechanically and a floating piston 21b separated by a body 22 of fuel. The piston 21b has inclined edges 23, 24 controlling the opening and closing of the suction port 25. During upward movement of the piston 21a, the port 26 is closed and fuel is trapped in the chamber 22 and pressure applied and leakage takes place through the port 33 into a chamber 32 where the pressure is adjusted by the valve 34. When the piston 21a closes the port 33, the volume of the liquid separating the pistons 21a and 21b is proportional to the speed of the engine, thus the time when the edge 23 closes the port 25 and injection commences is proportional to the speed. In a modification the port 33 is omitted and fuel is supplied to the port 26 at a pressure which is proportional to the engine speed. Fig. 7 shows an arrangement wherein piston 21b has a collar 52 and injection takes place when it is raised and uncovers the grooves 53. In a modification the leakage port 33 is replaced by a head in the piston having a small clearance between itself and the cylinder walls. In another modification the piston 21a has an inclined edge co-operating with a port leading from the pumping chamber 30 so that at excessive speeds this port is still open when the port 25 is closed and the delivery of the pump is automatically reduced. Fig. 11 shows a construction having a leakage port 33 and the piston 21b is formed as a thin collar and when the port 25 is closed it is opened almost immediately causing a preliminary injection, and then the piston 21b remains stationary until piston 21a engages it. Injection is completed when the edge 71 opens the port 65. The Specification as open to inspection under Sect. 91, also included the following constructions. Fig. 1 (Cancelled) shows a mechanically operated piston 1 engaging a small diameter piston 5. During the first part of the upward stroke they move together and when port 3 is closed they separate and the piston 5 is moved by the enclosed liquid in chamber 4. Fig. 20 (Cancelled) shows a mechanically operated piston 21a which delivers past a throttle passage 33. When the pressure difference across the throttle, due to the speed of the piston 21a, is sufficient to overcome the spring loading of the piston 21b, it is raised and opens the byepass port 107. The throttle passage may be formed in the pistons 21a or 21b. Fig. 24 (Cancelled) shows an arrangement wherein a preliminary injection takes place at a variable time when the piston 21a closes the leakage port 120 and finishes when the piston 21b opens the port 121. The main injection is effected by the piston 21a through port 121, throttle passage 124 and port 25. If the speed is such that the pressures on the ends of the piston 21b overcome the spring 29, the piston 21b is raised to open the port 107 and injection. ceases. This subject-matter does not appear in the Specification as accepted.