US2012128A - Device for injecting fuel into internal combustion engines - Google Patents

Description

Aug. 20, 1935. K. .1. E. HEssELMAN DEVICE EoR INJECTING FUEL INT0 INTERNAL coMEUsTloN ENGINES Filed Aug. 26, 1930 lig. 2.

Inventor: Knut Jj. E.l-lesselmann1 M H'Ls Attorney.

Patented Aug. 20, 1935 PATENT olivier: 1

nEvIcE'Fon rNJEcrlNG FUEL rN'ro INTER.-

' NAL ooMUs'rIoN ENGINES v Knut Jonas Elias Hesselman, Saltsjo Storangen,

' Sweden Applicaumnngust 26, 1930, serial No. 417,932 I. Y In Sweden September'9, 1929 s y .A

' scams. (ci. 12s-139) This invention relates to devices for injecting fuel into internal combustion engines of the kind which consist of pumping means, such as aA fuel pump, and one or more injection nozzles having, however, no special fuel valve but only one or more pressure valves between the piston of the fuel pump land the injection, nozzle or nozzles. In such devices it is known to interrupt A the lfuel injection by means of a special relief w valve which is opened during the compression stroke of the pump piston and thus places the compression side of the pump in communication either with the suction pipe of the pump or with a special pipe which leads the oil flowing through the relief valve back to the fuel container. 0n the opening of the relief valve during the compression stroke of the pump'piston, the pressure in theI pump space and the pressure pipe drops quickly to about atmospheric pressure. The

closing movement of the pressure valve does not take place instantaneously upon this drop, hown ever light the valve may be and however powerful its spring loading. As a result there is an opportunity for thehigh pressure which is set up in the, motor cylinder during the injectionl to force a part of the -oil back past the pressure valve before the latter has had time to close'. This in turn results in hot gases flowing through the fine holes in the injection nozzle into the *sup- 30 ply passage in the neighborhood of these holes and-producingxcoking or carbonization of the` oil in the holes and in the passage behind them. Such coking has a harmful influence on the injection process and on the atomization of the 35` oil.

'I'he object of the invention is to prevent the oil from iiowing. back inthisway. With this object in view, the relief valve, according to the present invention, opens into a' space provided 40 with arspring-loaded outlet valve, the springloading of which is such that this outlet valve l opens at a pressure which approximately correspends to or exceeds the pressure present in the .combustion space of the mtorat the end of the 45 injection, that-1s at the instant when the reliefv vvalve is opened. This valve arrangement makes y it impossible for the pressure in' the pump space to dop at the end ofthe injection period below p the pressure in the combustion space of the mo- 50. tor. Flowing back ofthe oil as described above is therefore prevented, as also is any coking in the`holes ofthe nozzles or in the passage bef hind them. .After the pressure valve has once returned to its closed position, .it can, of course,

' 65 peassumed that-a win hom tight and 1t is there- `the movable valve member fore possible subsequently to allow the pressure in the pump space to drop without risk.

In'order that the," vention may be clearLv understood and readily carried intoeifect, two de-4 vices constructed in accordance therewith now be described by way of 4example with reference to the accompanying drawing in which Figures 1r an'd 2 show longitudinal sections through the two devices. The device shownin Figure l is applicable to a low pressure motor in which lo l the end ofthe injection takes place at the same crank angle at all loads, while in Figure 2 a. device is shown for a motor with compression ignition in which 'the beginning of the injection l remains constant but ,the end of the injection 15 may be varied by opening the relief valve earlier or later in any Ysuitable manner.

f Referring first to Figure 1, the pump casing of a fuel pump or supply means is shown at I andthe pistonat 2. The piston 2 is driven by a cam 3 20 fixed-on ashaft 4. rlhis shaft can, for instance,` be the control shaft of an explosion or prolonged combustiomengine. As shown in the drawingthe pump is` provided with a suction valve 5, which y controls the communication between the pump f5 space or compression chamber and the suction passage l, and also with a pressure or check valve 8 whichis arranged at the'end of a pressure supply passage 9 immediately in front of an injection nozzle III. The latter projectainto the combustion space of a motor which-is not shown. A Arelief valve` I I is provided on a bore in line with the piston 2 and is opened by the piston 2 during the stroke. of the latter for the purpose of interrupting the fuel supply. The relief valve II controis the communication between the pump space or y compression chamber 6 and a chamber I2k which is separated from the suction passage I by al spring-loaded valve I3. The spring for biasing towards its seat is located between the valve member and an ad. justable plug screwed into a threaded hole of the pump casing. The spring-loading or biasing of this valve I3 is made such that the pressure re- K quired to open the valve is ofthe order of the pressure in the combustion space of the motor at -thne end of the fuel injection, that is on the opening of the relief valve II. The valve I3 thus ensures that at the interruption of the injection the pressurein the pump space l shall not drop below the pressure in the cylinder. The closing of the pressure valvef 'at the end of the injection period is effected bythe pressure in the combustion space and the spring for the valve. 'I'he pressure with which the spring forces the valve towards its combustion space at'the time when valve 8 closes.

The slower closingv of the pressure valve 8 has the advantage also that it minimizes undesirable` osclwlations o f Y'the fuel in conduit 9. The risk mentioned above of coking or carbonizing in the outlet holes or in the passage lof the nozzle I0 is consequently removed, since on account of the said pressure ratio no oil will iiow back past thepressure valve (8. The pressure required to open the valve I3 is, however, lower than that required to open the pressure valve 8, so that during the further movementof the piston 2, after this has opened the relief valve I I, oil can flow back from the chamber I2 to the suction passage 1.

In order that the pressure valve may be securely held inits closed position, the relief valve i may beI arranged in such a way that on the further movement of the pump piston the pressure in the pump space 6 or chamber I2 drops. This is effected, in the construction shown in Figure 1, by providing the relief valve I I with a passage I4 which opens above the guide I5 of the valve rod when the relief valve moves further outward. This arrangement has the advantage that any air which may be present in the pump space on the `starting of the motor is given an opportunity of escaping freely through the relief valve.v

In the construction shown in Figure 2, I as before indicates the pump or fuel supply casing, 2 the pump piston, 3 the driving cam, 4 the cam shaft, 5 .the suction valve, 6 the pump space or compression chamber and 1 the suction pipe. In this construction the pressure valve 8 is arranged ina special valve casing 23 immediately before an injection nozzle I0, the valve casing being mount- Ied in the cover of a motor cylinder and being placed by a pipe l24 in communicationwith the pressure'passage 9 in thepump casing I. The cam 3 in this case actuates the piston 2 througlr biasingmeans, such as a spring-loaded intermediate member 20. The relief valve II is not actuated by the piston but by a lever arm 2| actuated by the intermediate member 20 and carried on an eccentric 22, so,that it' can be set to open the relief valve earlier or later during the compression stroke of the piston 2. The relief valve controls the communication between the pump space or ...compression chamber 6 and'a chamber I2, from which a passag'e 25 and a pipe 26 lead tothe suction pipe 1. The spring-loaded valve I3 is placed in the passage 25. The spring-loadingj'of this valve is determined in"the'same way as is described above with reference to thevalve I3ishown Inthis construction also a pressure-reducing and air escape passage I4 is provided in the spindle of the relief valve II, and places the chamber I2 in communication with a by-pass passage 21,

leading to the passage 25, after the valve II has opened to a given extent. The invention is not limited to the constructions described but may be applied to other constructions. Fo'r example the air escape passage I4A not necessary. In the absence of this, a, pressure is preferably maintained inv the pump space which, during the whole time that'there is pressure in the cylinder space; is higher than that pressure. The height of the pressure in the pump space is determined by the spring-loading of the valve I3, and the time during which the pressure must be maintained is adjusted by the cam 3 of suitable dimensions. Again when provision is made for reduction of pressure or escape of air, the passage I4 may be replaced by any suitable passage or opening controlled by the relief valve and uncovered or opened after the latter has `moved off its seat through a predetermined disltance.

I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

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. In combination with an engine having 4a combustion cylinder, a device for injection of fuel into the cylinder, said device including a fuel pump comprisingv a compression space and a piston, at least one fuel injecting nozzle in said cylinder, a conduit for connecting said nozzle with the compression space, a pressure valve be'- -tween the pump andthe nozzle, a relief valve opening into the compression space, a chamber defined by the pump casing; said relief valve opening into said chamber, a spring-loaded outlet valve in said chamber, said outlet valve being so loaded by the spring, that the pressure necessary to open it is of the order of the pressure in backflow of gases from the combustion space into the compression space during the opening of the relief valve and before the pressurevalve is seated.

2. In combination with an engine having a combustion cylinder, a device for injection of fuel into the cylinder, said device including a fuel pump, a piston in said pump, at least one fuel injecting nozzle in said cylinder, a pipe connecting said nozzle with the compression space of said pump, apressure valve between the pump and the nozzle, a relief valve in said pump, a spacefin said pump, said relief valve opening into said space, a spring-loaded outlet valve in said space, said outlet valve being so loaded by the spring, that the pressure necessary to open it at least corresponds to the pressure in the combustion space of the cylinder at moment at which the relief valve is opened, a bypass for said outlet valve, said bypass leading from: said pump space and being opened after said relief valve has moved oi itsseat through a predetermined distance.

3. In combination with an engine having a combustion cylinder, means for injecting fuel into the cylinder comprising a compression chamber, pump means for supplying fuel to the chamber, a conduit between the chamber and the cylinder, a check valve means including a biasing spring in the conduit and means including said check valve for interrupting the fuel injection to the cylinderA comprising a valve means, and means for biasing the valve means against its seat with a pressure of the order of the pressure existing in the combustion space of the cylinder at the moment when the check valve'means is closed to prevent back flow of fuel from the cylinder into the conduit.

the combustion space of the cylinder to prevent y 4. lIn combination with an engine havingv 9x75 combustion cylinder, means for injecting fuel into the cylinder, a fuel pumping means having a compression chamber, a conduit between the compression chamber and the fuel injecting means, a pressure valve means in the conduit, another chamber, a relief valve means between the compression chamber of the pumping means and the other chamber actuated by the pumping means, an outlet valve in the other chamber, and means for biasing the outlet valve against its seat with a pressure of the order of the pressure existing inthe combustion space of the cylinder at the moment when the relief valve isl opened.

`5. In combination with an engine having a combustion cylinder, a nozzle for injecting fuel into the cylinder, a fuel pump comprising a compression chamber and a piston, a conduit between the compression chamber and the nozzle, a pressure valve in theoconduit, means for supplying fuel to the compression chamberfanother chamvber adjacent the compression chamber, a relief valve between the two chambers actuated by the piston, an outlet valve for the other chamber, and means biasing the outlet valve against its seat with a'pressure of the order of the pressure in the combustion space of the cylinder and adapted to permit opening of the valve when the relief valve is opened, the pressure of thev biasing means being lower than the pressure for forcing thev pressure valve against its seat.

KNUT- JONAS ELIAS HESSELMAN.

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