US 2521224 A
Description (OCR text may contain errors)
Sept. 5, 1950 G. s. KAMMER PILOT FUEL INJECTOR Filed July 10, 1945 2 Sheets-Sheet 1 2 Sheets-Sheet 2 Sept. 5, 1950 G. s. KAMMER PILOT FUEL INJECTOR Filed July 10, 1945 FL //M space I2 is in communication through the ducts I5 and I8 with the fuel supply and is thereby maintained full of fuel. After the plunger 2 has descended a short distance it covers the ports I6, I6 and so cuts off this communication. Pressure in the space I2 immediately rises and is exerted through the space around the upper part of the valve 25, 29, 30, the groove 32, the duct 26 and the corresponding nozzle orifice 39 above the valve face 31. The valve is thereby opened against the effect of the spring 38, and injection commences.
At the same time a certain proportion of the fuel will leak through the control orifice I9 and duct 20 backto duct I5 and the supply. The amount of fuel thus by-passed governs the amount of fuel which is discharged, through nozzle orifice 39, into the engine combustion space, that is, it governs the rate of pilot fuel discharge as well as the pressure in the pumping space.
At a certain point in the descent of the plunger 2 its lower edge covers the control port I9, but at the same time the lower edge of the groove 8 uncovers the port II]. The leakage through the control port I9 and duct 20 ceases, and all the fuel displaced by the plunger is delivered to the combustion space, a part of it as before through the groove 32, the duct 26 and one of the nozzle orifices 39, but the major part of it through the port I9, the duct 2I, the groove 36, the duct 35, the groove 34, the holes 33, 33, the grooves 21, 27 and the remainder of the nozzle orifices 39.
Thus an additional quantity of fuel, equivalent to the entire displacement of the pump plunger can now find its way into the engine combustion space, at the main rate of fuel discharge determined by the area of the plunger and the rate of lift of the pump operating cam. This quantity, obviously, is substantially greater than the initial rate, or pilot rate of discharge.
The plunger continues its stroke downwards to the full amount determined by the operating mechanism, but before the stroke is quite completed, the helical edge 9 uncovers one of the ports I6, whereby pressure in the space I2 is relieved, the remainder of the stroke merely serving to push fuel back to the supply. The spring 38 closes the valve 24, 31, since there is no pressure available to keep it open, and injection ceases abruptly. The duration of injection is determined by the time elapsing between the uncovering of the ports I0 and I6, and this again is determined by the position of the helical edge 9 due to rotation of the plunger 2 by means of the rack I. The drawings show the plunger set for full load or maximum injection.
It will be seen that the arrangement disclosed provides pilot injection at a reduced rate and main injection at a substantially higher rate. The rate of fuel discharge at any instant depends on the cross-sectional areas of the discharge orifices conveying fuel to the combustion space and of the leakage path returning fuel to the supply, the rate of lift of the operating cam and the area of the pump plunger, but it is independent of the engine speed, which only governs :the injection pressure.
There is no interval between pilot and bulk injection as in some known forms of injector, the valve remaining open continuously from the commencement of pilot injection to the conclusion of bulk injection.
Where reference is made above to times and rates, these must of course be understood in terms of crank angle, as is usual in internal combustion engine practice.
What I claim is:
1. A fuel injection nozzle for an internal combustion engine which includes a valve seating, a valve member having a face to cooperate with the seating, a stem joined to the valve member with longitudinal surface grooves therein, a sleeve tightly fitting and fixed to the stem to constitute the grooves into fuel ducts, holes through the sleeve communicating with the ducts near the said face of the valve member to constitute nozzle orifices, a surface on the valve member exposed to fuel pressure exerted in a direction to move the valve member in the direction of flow of the fuel in the ducts and thereby to open the valve, and resilient means opposing the said movement to keep the valve normally closed, said valve face being located adjacent said sleeve holes whereby the fuel finally leaves the nozzle orifices between the valve seating and the face on the valve member and substantially clear of said seating and face.
2. A fuel injection nozzle for an internal combustion engine, said nozzle including fuel supply ducts communicating with two different discharge ports of a fuel pump, a valve seating, a valve member having a face to cooperate with the seating, a stem joined to the valve member with longitudinal surface grooves therein, a sleeve tightly fitting the stem to constitute the grooves into fuel ducts, holes through the sleeve communicating with the ducts near the said face of the valve member to constitute nozzle orifices, communication means between some of the said ducts and one discharge port of the fuel pump, at least one other of the said grooves being longer than the remainder, communication means between said longer duct and the other discharge port of the fuel pump, a surface on the valve member exposed to fuel pressure from either group of ducts, whereby the valve member is moved by the fuel pressure in the direction of flow of the fuel in the ducts, and resilient means opposing the said movement to keep the valve normally closed, the valve being so located that the fuel finally leaves the nozzle orifices between the valve seating and the face on the valve member.
GEORGE STEPHEN KAMMER.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS