Patent GB-843427-A (GB)
Title: Improvements in carburetting devices operating by injection of fuel into the induction pipe of an engine
Inventor: MENNESSON ANDRE LOUIS
IPC: F02D9/00
Filed: 1958-10-22
Abstract: 843,427. Fuel injection carburetting apparatus. SOC. INDUSTRIELLE DE BREVETS ET D'ETUDES S.I.B.E. Oct. 22, 1958 [Nov. 14, 1957], No. 33832/58. Class 7(3). [Also in Group XXVI] In a carburetting device operating by injection of fuel into the induction pipe of an engine and supplied by a pumping system whose delivery is proportional to the speed of the engine, the pumping system is constituted by the combination of a rotary pump preferably of the centrifugal type and of a reciprocating pump preferably of the diaphragm type both having deliveries proportional to the engine speed, this combination being so arranged that the rotary pump is automatically substituted for the reciprocating pump to effect delivery when the speed exceeds a predetermined value and vice versa. In Fig. 1 the rotary pump a is preferably constituted by a centrifugal pump driven at a speed proportional to that of the engine and again preferably by a rotary-chamber pump 9a. The pump a is fed from a reservoir b with a superabundant quantity of fuel by means of a pump c or where appropriate by gravity. The reciprocating pump e is preferably constituted of a diaphragm pump driven synchronously with the engine. At low speeds the pump e supplies fuel through the valve h at its own delivery rate. On the other hand at high speeds the rotary pump delivers fuel at a continuous and regular delivery rate into the pipe # and the pump e can at the most cause the value of the pressure in this pipe to fluctuate. In order to avoid premature wear on the reciprocating pump e it is advantageously so arranged that it is rendered inoperative when the speed of the engine exceeds the limit valve and this operation of rendering the reciprocating pump inoperative can be carried out under the action of the delivery pressure of the rotary pump either directly on the diaphragm (or piston) of the reciprocating pump or in a separate capsule device. The induction pipe is indicated at j and the delivery correcting means at k the latter generally controlling an adjustable leakage. A slight permanent leakage determined at the jet m is advantageously provided. Referring to Fig. 2 the centrifugal pump is essentially constituted by a rotatable chamber comprising a bearing plate 1 and a cover 2 connected together in a fluid-tight manner. The part 5 is fast with the main body of the apparatus. The shaft 7 is driven by the engine and carries a cam 8 which acts upon a push rod 9. The chamber 10 is connected at its lower portion to the main feed pump 12 through the duct 13 and a float chamber 15. The pump 12 delivers fuel through a pipe 19 which opens into the interior of the rotary chamber 1, 2. The part 5 comprises a liquid take-up or duct 21 (Fig. 3) so constructed as to utilize not only centrifugal force but also the dynamic effect of the ring of liquid fuel rotating in the chamber 1, 2. Upstream of the jet these are arranged in the duct 21, two non-return valves 23, 24 permitting the outflow of fuel only to the injector or injectors and between these two valves there debouches a duct 25 which communicates with a chamber 26 closed by a deformable diaphragm 27. This diaphragm is actuated by the cam 8 through the medium of the push rod 9 and the lever 30. The pressure which exists in the ducts 21 acts on the diaphragm 36 and when the pressure reaches a predetermined value which corresponds to a certain rotational speed of the engine the diaphragm is displaced and the lever 30 is moved counterclockwise so that the push member 9 no longer comes into contact with the cam 8. Fuel delivered through the duct 21a finally arrives at one or more injectors constituted by a hole of small dimension 51 opening into a chamber 52 which' is connected to atmospheric pressure on the pressure of the air inlet 53 through a hole 54. The presence of the Venturi 59 is not obligatory but makes the operation of the diaphragm 44 more sensitive. It is possible to dispense with the parts 36, 37, 38 and the duct 40 and use the diaphragm pump 27 itself in their place. For this it is sufficient to give the diaphragm of the latter sufficiently large dimensions. When the engine is driven by the starter the diaphragm 44 occupies its extreme position towards the left of Fig. 2. At this instant arrangements are made to cause the foot 43a of the needle 43 to bear against the edge of the orifice 42 and to close the same almost hermetically. An advantage of the centrifugal pump device constituted by a rotary chamber consists in degassing the fuel. The diaphragm pump 27 at slow running or low speeds of the engine may cause an injection of fuel which begins or terminates at accurately determined instants. It is possible to provide a correcting device taking into account the temperature of the air within the induction pipe 56. This device may be controlled by a temperature sensitive element 60 An accelerating pump can be provided which is constituted by a chamber 66 and associated parts. There can also be provided a device for starting and running the engine in the cold state. A manual device or preferably an automatic device such as a device sensitive to the temperature of an appropriately chosen point (in this particular case this has been represented by a bimetallic strip 72) acts on a first lever 73 which regulates the admission of air to the induction pipe. It also acts on a second lever 74 controlling a valve 83 and on a lever 75 which actuates a cam 34. As soon as the engine has started up the valve 81 is lifted away from its seat permitting the entry of a considerable quantity of air which results in increasing the engine speed generally a sufficient increase in speed for the rod 35, coming to act on the lever 30, to diminish or even discontinue the delivery of the pump 27. It is possible to replace the auxiliary air intake 77 by a cam system of known type adapted to partially open the throttle 57. A last correction which may have to be effected is altimetric correction. To this end the correction device sensitive to the vacuum in the induction pipe diaphragm 44) must be replaced by a barometric capsule (Fig. 6, not shown). The length of the needle 43 and the calibration of the spring 45 may be so chosen that when the vacuum in the induction pipe exceeds a predetermined value the needle 43 issues completely from the orifice 42, at this instant and as long as the vacuum remains sufficiently high the injectors 51 are no longer supplied.