Fuel supply devices for internal combustion engines

#This invention relates to supply devices for internal combustion engines of the kind which inject fuel into the engine inlet manifold.

#Prior art fuel supply devices of the kind set forth comprise a driver-controlled main throttle element located in the intake pipe of the engine and an auxiliary throttle element usually, but not necessarily, disposed upstream of the main throttle element and opening progressively and automatically in proportion as the rate of air flowing through the inlet tube increases. To this end, the auxiliary throttle element can be connected to a movable element subjected to the air pressure prevailing in that portion of the intake pipe which is between the auxiliary throttle element and the main throttle element (at least when the main throttle element is disposed downstream of the auxiliary throttle element). The extent of opening of the auxiliary throttle element is a yardstick for the rate of air flow through the inlet manifold, and a pressure drop which is either substantially constant or which is a predetermined and increasing function of the engine intake air flow is established between the upstream and downstream sides of the auxiliary throttle element.

#Such a device is described in French Patent Specification No. 1,519,890.

#FIG. 1 is a very diagrammatic view of the complete system in cross section;

#FIG. 2 is a view on an enlarged scale of the injector of the system of FIG. 1 in section along the injector axis;

#FIG. 3 is a view in cross-section along line III--III of FIG. 2, and

#The device whose elements are shown in FIG. 1 in their normal positions comprises an air intake pipe 1 connected to an engine inlet manifold 2. Disposed in the intake pipe 1, starting from an air entry 3 which usually has an air filter (not shown), are an auxiliary throttle element 4, a chamber 5 and a main throttle element 6 operated by the driver through a linkage (not shown). In the embodiment shown both of the elements 6 and 4 are butterfly valves.

#The auxiliary throttle element 4 is connected to an axle 7 which carries a lever 8. The lever is connected by a rod 9 to a deformable diaphragm 10 which operates element 4. Diaphragm 10 separates a capacity 11, which communicates via a passage 12 with chamber 5, from another capacity connected to air entry 3 via a passage 13. A spring 14 biases auxiliary throttle element 4 toward closure whereas the underpressure transmitted through passage 12 tends to open element 4. A mechanism of this kind is well known and opens the element 4 when the engine draws air because of the main throttle element 6 opening, until an underpressure which depends on the characteristics of the spring 14 is produced in chamber 5. Consequently, the opening angle of the automatic element 4 is a yardstick of the rate of engine air intake, the relationship depending upon the characteristics of the spring and the opening being accompanied by a slight pressure drop between the upstream and downstream sides of the element 4.

#By way of axle 7 the element 4 is connected to a lever 15 moving a needle 16 or the like; a portion 17 of the needle is tapered and has a cross-section which varies in accordance with an appropriate pattern and moves in a calibrated passage or orifice 18. By way of passage 18, a chamber 19 which a passage 20 connects to the delivery of a fuel pump 21 communicates with a chamber 23 from which a passage 24 extends. Pump 21 draws fuel from a tank (not shown) through a pipe 22.