From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Article from Automotive Industries describing the operation of a new diaphragm pump for an AC fuel supply system.
| Identifier | ExFiles\Box 53\1\ Scan041 | |
| Date | 5th March 1927 | |
| Automotive Industries March 5, 1927 369 Diaphragm Pump Utilized in New AC Fuel Supply System Operates through lever from push rods, tappets or eccentrics located either on camshaft or any other revolving shaft. Fuel drawn through strainer before being forced into carburetor. A NEW fuel supply system introduced by the AC Spark Plug Co., Flint, Mich., comprises a diaphragm pump which is operated through a lever from push rods, tappets or eccentrics located either on the camshaft or any other revolving shaft. The pump, which is 4 in. wide by 5 in. high, sucks the fuel from the tank at the rear of the car through a combined gasoline strainer before forcing it into the carburetor. In the design of this unit every effort was made to insure reliable operation and long life. The diaphragm and valves are made of non-metallic materials; as any water contained is separated from the gasoline by the strainer, there is no danger of sticking and freezing of the valves, and, although the pump has a capacity of from twice to three times the maximum requirements of the largest vehicles, it always delivers fuel in accordance with the needs of the engine. All of the working parts of the pump are inclosed in a die-cast housing, and the drive is obtained from any convenient part of the engine which provides a reciprocating motion of from 3/16 to ¼ in. Referring to Fig. 1, the diaphragm A is made of specially treated cloth which is said to be unaffected by gasoline and benzine or benzol. It is held together by two metal disks and is forced upward by the pump spring C. When it is all the way up the diaphragm almost fills the pump chamber M, and then, when it begins to move down, it creates a high vacuum, which assures operation even at low speeds. It is claimed that a ¼ in. motion of the diaphragm can be maintained indefinitely without injury, because of the extreme flexibility of the material. The diaphragm moves the full distance only when the carburetor float chamber is empty. At all other times the motion is greatly reduced, being always directly proportional to the fuel consumption of the engine, and under ordinary driving conditions the pulsating motion amounts to only about 0.003 in. When the diaphragm is in the depressed position, due to there being sufficient fuel in the carburetor float chamber, the reciprocating motion of lever D will merely cause linkage F to move to the right, as indicated by the arrow. The complete cycle of operation is as follows: Eccentric H on shaft G lifts rocker arm D, which is pivoted at E and which pulls linkage F, together with diaphragm A, down against the pressure of spring C, thus creating a vacuum in the pump chamber M. {Mr Moon / Mr Moore} Fuel from the rear tank enters chamber M at J through strainer K and suction valve L. On the return stroke the pressure of spring C pushes diaphragm A up, thereby forcing fuel from chamber M through the pressure valve N and opening O into the float chamber of the carburetor. When the carburetor bowl is filled the float will shut off the inlet valve, thus creating a pressure in pump chamber M. {Mr Moon / Mr Moore} This pressure will force diaphragm A down against spring pressure C and it remains in the downward position until the carburetor requires more fuel and the needle valve opens. Spring P serves to keep operating lever D in contact with eccentric H, to eliminate noise. LEFT: Fig. 1. Sectional view of AC fuel pump and strainer. ABOVE: AC fuel pump with strainer attached | ||