US2283725A

US2283725A - Fuel-injection nozzle valve

Info

Publication number: US2283725A
Application number: US268602A
Authority: US
Inventors: Eichelberg Gustav
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-04-11
Filing date: 1939-04-18
Publication date: 1942-05-19
Anticipated expiration: 1959-05-19

Description

May 19, 1942. e. EICHELBERG FUEL-INJECTION NOZZLE VALVE Filed April 18, 1959 VIVVENTOR A GUSTAV E/Cl/ELBL'RG ATTORNEYS.

Patented -May 19, 1942 UNITED STATES PATENT OFFICE 2,283,725 FUEL-INJECTION NOZZLE VALVE Gustav Eichelberg, Zurich, Switzerland Application April 18, 1939, Serial No. 268,602

In Germany April 11, 1938 Claims. (Cl. 299-'-107.6)'

I. Fuel-injection valvesare known which operate with a pressure accumulation of fuel. .Such accumulation can be arranged to take place below auspring-loaded piston which is raised by the fuel or, alternatively, the actual compression of I the fuel itself can be used, this compression taking pIace-in a chamber arranged near to and connected with the injection nozzle with which I ;.-,i s associated the valve seat onto which a needle yalveis pressedby the action of a valve spring.

The present invention relates to the second of turelifting of the valve needle against the force of the valve spring, under the action of the pres- .sure of .the fuel delivered from the pump, by causing this fuel pressure to act upon the end of the needle remote from the valve-seat. In this way the injection is initiated by relieving the pressure in the fuel-supply pipe and thereby relieving the pressure on the upper end of the needle. The pressure of the fuel to be injected acting on the lower end of the needle then raises the latter, allowing the injection to takeplace.

This injection continues until the pressure of the accumulated fuel has fallen to so low avalue that the valve spring depresses the needle against the falling pressure of the fuel onto the valve-seat.

.It is evident that precautions must be taken that the relief of the pressure on the outer end of the needle, which arrests the injection, does not also diminish the pressure in the pressure acpressure in the accumulating chamber is only relieved through the throttling passage in a very slow and gradual manner which does not substantially afiect the injection.

The foregoing systems suffer however, from a number of drawbacks.

In the first place, the chamber at the upper end of the needle is of disproprotionately large size owing to the valve spring being located in it.

The volume of fuel present in this chmber must,

after every drop in pressure, be again raised from zero-pressure to the injection pressure and to effect this a large, additional volume offuel has like low-viscosity fuels. I

to be delivered by the pump. This additional volume of fuel may, when the apparatus is of small dimensions be many times, the volume of the fuel normally injected. Furthermore, the losses through leakage between the stem of the needle and the bearing therefor, even when the surfaces are a ground fit, are very considerable, more especially when operating with petrol and Lastly, the return flow losses already referred to as occurring when a throttling passage is used, while depending on the construction of the valve, are not o insignificant as'not to exercise a detrimental efiect on the operation of the apparatus.

It is an object of the invention to provide a fuel-injection valve in which the above drawbacks are avoided, this being done mainly by reducing the size of the upper chamber.

In Figure 2 of the accompanying drawing, a construction according to the invention is shown in'greater detail by way of example, while in Figme 1 a knownconstructional form of a fuel-injection valve is shown for the sake of comparison and to facilitate the understanding of the inven tion.

The fuel injection valve according to the invention comprises a chamber in which pressure accumulation of the fuel takes place, a valve adapted to close the outlet from the chamber, a spring pressing the valve on to its seat, and a second chamber intowhich part of the valve extends and into which fuel is adapted to be admitted under pressure so as" to act on the valve to press the latter towards its seat, the said spring being located in the pressure accumulating chamber.

The valve is preferablyarranged so that, when raised from its seat, a part of it co-operates with a fixed member to close the passage through which fuel is delivered to the pressure accumulating chamber from the second chamber.

According to a further practical feature of the invention arrangements are made that, when a throttling passage, and not a non-return valve, is provided between the second chamber and the 'pressure accumulating chamber, this throttling passage-is arranged in such a way as to put the pressure accumulating chamber in communication with that section of the second chamber which, during the injection or when the needle is lifted, is shut off from the fuel-pipe by the valve member which limits the stroke of the needle.

In this way, not only is the back-flow loss reduced to a very great extent because any such back-flow is possible only during the brief moment when the needle is lifted, but, in addition to this, a dimculty now to be explained is successfully overcome.

In the case of pressure accumulating valves making use of pure liquid accumulation, there is the well-known difficulty that the proportion of the idle-running to the full-load quantity is approximately 1 to 6, so that, by virtue of the compressibility of the fuel, the pressure rise in the accumulating chamber above the residual pressure at the time of the closing'of the valve varies in the proportion 1 to 6 for idle-running and full load respectively. This tends to produce either a very high fuel-pressure with full-load, when the pressure accumulatingchamber is comparatively small, or, too small a rise in pressure when running idle-if the pressure accumulating chamber is comparatively large. This small rise in pressure when running idleis not suflicient to overcome the difference between the closing and opening pressures of the needle. (Cf. Dr. Ing. G. Eichelberg On means for compressorless fuel injection. V. D. I. Zeitschrift vol. 70, Nr. 32, August 7, 1926, page 1079 et. seq.)

As a resultof the alteration of the position of the throttling passage as described above, an additional quantity of fuel isabstracted from the pressure accumulating chamber and will flow back through the throttling passage, though only during the moments when the needle is opening andclosing and not when the needle is in its raised or open position. This back-flow does not, therefore, coincide with the injection period of the needle. It is of approximately equal volume for full-load and idle running. If, for instance, the back-flow volume is assumed to be equal to the volume injected when running idle, then the ratio of the total quantity to be stored when running idle to that to be stored at full load is 1+1 to 6+1, or 2 to 7, and is no longer 1 to 6. The risk of any interruption of the injection with partial load can thus be eliminated.

In the known form according to Figure 1, fuel is fed to the valve 1 through the pipe 2. The pressure accumulating chamber 5 is here supplied through the pipe 2, and the fuel is admitted to the second chamber 6 through the pipe 4. A non-return valve 3 may be provided which closes whenever the pressure in the fuel pipe drops or, alternatively, the chamber 5 may be connected with the chamber 5by means of a throttling passage l. The valve closing spring 8 is located in the chamber 6. The operation of this type of nozzle valve is well known and its drawbacks have already been pointed out.

In the form of construction according to the invention shown, by way of example, in Figure 2, the spring 8 is arranged in the accumulating chamber 5 below the bore or bearing for the valve needle 9, which bore is formed in the valve body I. A throttling passage 1 is provided between the chamber 5 and the small space above the stem of the valve, the passage opening into said space at such a. point that when the needle 9 is raised, it acts as a valve to cut off the throttling passage 1 from the fuel pipe. It will be noted that the effective surface of the valve head in its closed position on which the hydraulic pressure is upwardly directed is greater than that on which the hydraulic pressure acts downwardly The manner in which this fuel-injection valve operates is, briefly, as follows:

The fuel enters through the pipe 2 into the upper part of the bore for the needle 9 which constitutes the second chamber. The fuel then passes into the accumulating chamber 5 by way of the throttling passage 1. Wheneverthe pres,- sure in the fuel feedplp drops, the needle 5 is, in consequence, lifted by reason of the differential under surface of the valve head and shuts oil. the throttling passage from the fuel pipe. The fuel is then injected into the engine cylinder through the apertures H. As soon, however, as the pressure in the storage chamber 5 ,has fallen sufficiently, the needle 9-is returned to its seat by the action of the spring 8. In this way the communication between fuel-pipe, throttling passage and accumulating chamber is again established and the latter is refilled, that is, the pressure therein again raised, the sequence of operations being repeated when the pressure in the fuel pipe again falls.

The correct positioning of the throttling passage is of great importance for the operation ofthe device of the invention. Thus, for example, any arrangement in which the throttling passage connects the chamber 5. with the pipe 2 g at a point above the upper limit of the stroke of the valve stem isundesirable because there is no closing of .the passage when the needle is raised. 1 There are many modified forms ,of construction that might be specified and which fall within the scope of the invention; and donot depart from its fundamental principle. Thus for in,- stance, the throttling passage might be replaced by a different system of communication such as grooves, channels and the like, or the needle stem might evenmerely be made a loose fit in the bore.

Having now particularly described and ascertained the nature of. my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. A fuel injection nozzle having a chamber in which pressure accumulation of the fuel takes place, said chamber being provided with an out let, a valve element adapted to close said out let, a second chamber into which part'of the valve element extends and into which fuel is adapted to be admitted under pressure so as to act on the valve element to press the same towards its seat, and a passageway leading from the accumulation chamber and so constructed and arranged as to be in communication with the second chamber when the valve element is in its closed position, said valve element in its a part of said valve element extending into said second chamber the fuel under pressure in said second chamber acting on the valve to urge it into its closed position, and means normally connecting the two chambers to feed fuel from the second chamber to the accumulation chamber and remaining open during the period that the valve is closed, said fuel feeding means being so constructed and arrangedas to be rendered inchamber to the accumulation chamber, said fuel f feeding conduit being so constructed and aroperative when the valve is lifted by the fuel under pressure in the accumulation chamber upon fall of pressure in the second chamber.

3. A fuel injection nozzle as claimed in claim 2, wherein the second chamber comprises a bore in the valve body receiving snugly the stem of the valve, said connecting means comprising a throttling passageway opening into the accumulation chamber and leading from an aperture opening into the bore intermediate the end of the valve stem when the valve is in the closed position and the opposite end of the bore.

4. A fuel injection valve having a chamber in which pressure accumulation of the fuel takes place, said chamber being provided, with an outlet, a needle valve controlling said outlet and located within the accumulation chamber, a second chamber coaxial with the outlet, the valve having a stem passing into said second chamber, a conduit for supplying said second chamber with fuel under pressure, a throttling passageway leading from the pressure accumulating chamber to the second mentioned chamber and opening into said latter chamber at a point which becomes covered by the stem of the valve when the valve is opened by the pressure of the fuel within the accumulation chamber-upon fall of pressure in the fuel conduit.

5. A fuel injectionvalve as set forth in claim 4, including a spring located in the pressure accumulation chamber, and acting to urge the valve to its closed position.

6. A fuel injection valve set forth in claim 4, wherein the second chamber constitutes a cylindrical bore within which the stem of the valve snugly fits.

7. A fuel injection valve comprising a body having a chamber in which pressure accumulation of the fuel takes place, said chamber being provided with an outlet, a solid unbored needle valve controlling said outlet, a spring located in the chamber and acting on the valve to urge it to the closed position, said valve having a cylindrical stem; a cylindrical bore coaxial with the outlet and extending from the pressure accumulation chamber, the stem of the valve being slidably received within said bore; a fuel conduit connected with the bore beyond the end of the valve stem and adapted to charge fuel under pressure into said bore, and a passageway connecting the pressure accumulation chamber with the portion of the bore unoccupied by the valve stem when the valve is in the closed position, and opening into the bore at a point which becomes covered by the valve stem when the valve is lifted to open position.

8. A fuel injection valve comprising a chamber, an inlet for the supply of fuel directly into said chamber,- an accumulation chamber in which fuel pressure is built up, said accumulation chamber being provided with a valve seat and with an outlet leading from said valve seat, a valve element having a head of reduced crosssection adapted to control said outlet, a spring located in the accumulation chamber and positioned to urge the valve element against its seat, the pressure of the fuel in the first mentioned chamber acting on the valve element to urge it to its closed position, and a conduit connecting the two chambers to feed fuel from the first ranged as to be closed when the valve is lifted by the fuel under pressure in the accumulation chamber. i

9. A fuel injection nozzle for combustion engines, said nozzle having a chamber in which pressure accumulation of the fuel takes place, said chamber having an inlet for fuel under pressure and provided with an outlet, a pressureoperated valve element having a head adapted to close the outlet from the chamber, a spring pressing the valve head onto its seat, a second chamber into which part of the valve element extends and into which fuel is adapted to be admitted under pressure so as to act on the valve element to press the valve head towards its seat, the. pressure in said pressure accumulating chamber acting to open the valve, the said spring and valve head being located in the pressure accumulating chamber, and said accumulating chamber being sufiiciently large to effect discharge through said outlet of the amount of fuel required for full load operation of the combustion engine upon reduction of the fuel pressure acting on the valve element in the second chamber and consequent opening of the valve element, and a passageway between the chambers normally serving to deliver fuel from the second chamber tothe inlet of the pressure accumulating chamber and connecting the two chambers continuously while the valve is closed, the valve element being so constructed and arranged that when raised from its seat, a part of it acts to close said passageway.

10. A fuel injection nozzlefor combustion engines, said nozzle having a chamber in which pressure accumulation of the fuel takes place,

- said chamber having an inlet for fuel under pressure and provided with an outlet, a pressureoperated valve element having a head adapted to close the outlet from the chamber, a spring pressing the valve head on to its seat, a-second 'chamber into which part of the valve element extends and into which fuel is adapted to be admitted under pressure so as to act on the valve element to press the valve head towards its seat, the pressure in said pressure accumulating chamber acting to open the valve, the said spring and valve head being located in the pressure accumulating chamber, and said accumulating chamber being sufiiciently large to effect discharge through said outlet ofthe amount of fuel required for full load operation of the combustion engine upon reduction of the fuel pressure acting on the valve element in the second chamber and consequent opening of the valve element, and a passageway between the chambers normally serving to deliver fuel from the second chamber to the inlet of the pressure accumulating chamber, and a feed pipe for delivering fuel to the second chamber, said passageway being of throttling dimensions and communicating with that section of the second chamber which is cut off from the feed pipe upon reduction in the pressure in said pipe and movement of the valve element within said second chamber to open valve position.

GUSTAV EICHELBERG.