US2794682A - Fuel injector pump - Google Patents

Description

June 4, 1957 c. A. GONGWER FUEL INJECTOR PUMP 3 Sheets-Sheet l Filed Feb. 4. 1955 iii NF wk.

IN VEN TOR. CALVIN A GOIVGWER A T TORIVEY June 4 1957 c. A. GONGWER FUEL INJECTOR PUMP Filed Feb. 4, 1955 3 Sheets-Sheet 2 53 7 49 ll 57 I T 8 INVEN TOR. CALVIN A GONGWER A T TORNE Y June 4, 1957 c. A. GONGWER 3 Sheet s-Sheet :s

QALVIN 0 R ATTO United States Patent FUEL INJECTOR PUMP Calvin A. Gongwer, Glendora, Calif., assignor to Aerojet- General Corporation, Azusa, Calif., a corporation of Ohio Application February 4, 1955, Serial N0. 486,120

4 Claims. (Cl. 299-.107.6)

This invention pertains to fuel injection, and more particularly to an intermittently operating injector pump which is self-cycling.

There aremany known varieties of fuel injector pumps and metering devices which act to inject quantities of liquids into such means for their use as combustion chambers. Generally speaking, these pumps are not selfcycling; that is, their periodicity of operation is ordinarily dependent upon conditions in related apparatus, such .as cams to move control elements in the pump, or chambers responsive to engine cylinder compression and the like. In addition, these existing devices allow for relatively little adjustment of the quantity of fuel contained in each pulse, the amount passing through at each actuation depending largely on the geometry of the system. In the absence of an accumulator, discharge is ordinarily limited to the amount which enters the fuel supply line at supply pressure during the period the pumps discharge port is open.

Since such devices rely on other components, they are necessarily composed of more parts than if self-contained, and are therefore complex and provide extra opportunities for breakdown.

An object of this invention is to provide a pulse-type fuel injector pump capable of injecting liquids (which may be molten metal if desired) into such means as a motor cylinder, in which the frequency of pulsation of injection and the quantity of fuel per injection can be cont-rolled by simple pressure adjustments, and which is not dependent upon external devices for its cyclical operation. For example, this invention has no necessary interconnection with rotating, commutating or-reciproeating means for its timing or quantity adjustments. An additional object is to utilize the pressure of the fiuid fuel itself for actuation of the pump.

A feature of the invention resides in a pintle assembly which customarily closes an injection orifice discharging from a fuel chamber in the injection pump, and an accumulator for building up fuel pressure and volume, whereby the pintle is lifted from the injector orifice when the forces holding the pintle down are slightly more than counterbalanced by fuel pressure tending to lift the pintle, and the accumulated fuel is discharged from the injector jet. When the pressure fails in the fuel chamber after discharge, the pintle is again seated, and the abovedescribed steps are repeated automatically without dependence upon any other mechanism. By constructing the injector orifice of such size that pressure falls relativeyl slowly in the fuel chamber, the pintle assembly is caused to rise quickly.

An additional feature resides in the means for controlling the frequency of pulsation, which comprises a simple valve regulating the flow of the fuel to the accumulator.

Still another feature resides inmeans for causing the pintle assembly to remain in its customary position, thereby closing the orifice while pressure builds up in the 2,794,682 Patented June 4, 1957 accumulator. In cooperation with the accumulator these means determine the quantity of fuel in each pulsation. One such means is a substantially constant fluid pressure exerted as the pintle assembly to force it toward the injection orifice. As alternate means, the pintle assembly may be spring loaded so as to tend to remain in its customary position.

These and other features of my invention will be fully understood from the following detailed description and the accompanying drawings, of which:

Fig. 1 is a plan view of an injector and accumulator according to the invention;

Fig. 2 is a cross-section view of the accumulator;

Fig. 3 is an end view taken along line 3-3 of Fig. '2;

Fig. .4 is an end view taken along line 4-4 of Fig. 2;

Fig. 5 is a cross-section view of the injector;

Fig. 6 is an end view taken along line 66 of Fig. 5;

Fig. 7 is a cross-section view taken along line 7-7 of Fig. 5.;

Fig. .8 is across-section view taken along line 8-a8 of Fig.5;

'Fig. 9 is across-section View taken along line 9-9 of Fig. 1 showing a T connection between the injector, "accumulator and supply line in detail; and

general orientation and relationship between the components of an injection device according to the invention. Anaccumulator 10 is joined to an injector 11 by a conduit 12 having a T joint 13 in its length. A fuel supply line 14 extends from the T, and is therefore fluidly connected with conduit 12. A frequency control valve 15 is placed in the fuel supply line. This valve may be of any appropriate variable orifice design.

The injector 11 is shown in detail in Fig. 5, and has a body or cylinder member 16 which encloses a fuel chamber 17, heater cavities 18, injection jet 19, injection nozzle .20, and an opening 21 by the nozzle 20. The body is a central shaft housing 27 which expands to form a cylinder 28. A lubricant passage 29 with a fitting 30 threaded therein leads from the outside of'the cylinder member to the shaft housing. Fitting 31 connects with a further lubricant passage (not shown) permitting a silicone type lubricant to flow therethrough.

A vent passage way 32 connects the outside of the unit to the inner end of the cylinder 28, and a fitting 33 allows connections to be made therewith. As best shown in Figs. 6 and 8 two additional fittings 34 are disposedat the end of coolant passages in the cylinder member. Passages 35 are drilled parallel to each other and into the member, and an intersecting passage 36 connects the two so as to form a continuous fluid conduit. A stopper 317 is inserted in passage 36 to blank off the un-needed length of conduit. This provides for steady circulation of coolant through the passages.

An end plate 38 having a central tapped passage '39 and holes 40 matching threaded recesses 41 in the cylinder member is attached to the cylinder member by capscrews 42. The central tapped passage 39 leads to the outside end of the cylinder 28.

A pintle assembly 43 comprises a piston 44 within the cylinder having a resilient ring 45 in a groove 46 around its periphery to inhibit gas leakage thereby, and a shaft 47 affixed to and depending from the piston. The shaft 47 passes through the shaft housing 27 so as to be axially slidable therein, and has a tapered seat portion 48 onthe end of the shaft inside the fuel chamber 17. The tapered seat portion faces the injection jet.

As will be appreciated from Fig. 5, when the pintle is seated, the projection of the area of the shaft remaining inside the fuel chamber and facing the jet onto a plane perpendicular to the axis of the shaft is greater than such a projection of any other part of the shaft facing in the other direction within the fuel chamber, that is away from the jet. In this manner, while the pintle assembly is seated, any pressure in the fuel chamber will tend to unseat it by forcing it away from the jet. An annular seat member 49 having a sloping shoulder 50 at the end adjacent the fuelchamber is threadably inserted in the injector orifice as a convenient means for sizing the jet. The shoulder 50 has a smaller'outer diameter than the tapered seat portion 48. 7

Since this injector device may be used to handle molten metals, lithium for example, means are provided for heating the injector. These means comprise resistance units 52 which are fitted into the heater cavities 18. Leads 53 connect with buss bars 54 separated from the pump and from each other by layers 55 of insulating material. A flanged end plate 56 is held to the body by screws 57, and electrical leads 58 pass through this plate to the buss bars. The buss bars, insulation, and leads may be fastened to the body by means such as screws 59.

The accumulator is of a springing type, such that the volume of fluid therein increases as the pressure increases. It comprises a circular shell 61 having a barrier 62which form's compartments 63, 64 at opposite ends of the shell. Fluids for the injector do not enter compartment 63. A disc-shaped resistance type heating element 65 is fitted into compartment 63, and is held there by a plate 66 which is itself retained by a snap-ring 67 in groove 68. Electrical leads to the heating element pass through fitting '70, and are attached to the element by studs 71. 7

Compartment 64 has a bellows assembly 73 therein. This bellows assembly comprises a flanged member 74 to bear against shoulder 72 in the shell, and a flexible bellows 78 attached to the flanged member. An end plate 77 caps the end of the bellows away from the flanged member. This bellows has elastic properties which tend to diminish its length when pressure inside it is decreased. Reinforcing rings 76 are inserted between each convolution of the bellows. These reinforcing rings also act as guides and can bear against the wall of the compartment 64,as the bellows expand or contract. An annular insert 79 having heater cavities 79a fits within the bellows and has a fluid conduit 80 through its center to an expansion chamber 81 within the bellows assembly. Resistance heater elements 82 are placed in the cavities 79a, their leads 83 entering through a fitting 84 and a passage in a retainer plate. 85. This retainer plate bears against the annular insert 79, which in turn bears on the flange member 74. The retainer plate is held in place by snap rings 86 which are fitted in grooves 87 in the shell. The fluid conduit 80 continues through the retainer plate, and attaches to conduit 12.

Fuel supply line 14 and conduits 12 are interconnected by a T 13 of conventional manufacture. The T has two' aligned side ports 88 for attachment to conduit 12, and a third port 88a for connection to the frequency control valve 15.

A quantity control valve 89 interconnects a source of fluid pressure (not shown), with passage 39 and the cylinder 28 in the fuel injector. The source of pressure may be from the fuel supply itself, or liquid or gas from a system under pressure. This valve is of a pressure regulating type which maintains a substantially constant fluid pressure in the cylinder.

Fig. 10 shows an optional quantity regulating means, in which the cylinder 28 may be provided with a spring 90 between the piston 44 and a cap 91 which is threadably engaged to the injector pump. By screwing down thecap, the spring maybe preloaded as desired to vary the pressure on the pintle assembly.

The operation of the device will now betdescribed. Quantity control valve 89 is first opened to admit a fluid under pressure into cylinder 28. This source might be such as a flask of pressurized nitrogen. Preferably it should be a fluid which would not react with the fuel in the fuel chamber 17 in case of leakage through the shaft housing 27. This pressure will force the pintle assembly down to its customary position where the tapered seat portion bears against shoulder 50 to close the injection jet 19. At this position, an outer annular ring on the face of the tapered seat portion 48 remains inside the fuel chamber, while the central part of the seat portion 48 is sealed off from the fuel chamber and stands within the injection jet 19.

The net force with which the pintle assembly is held in the customary position is equal to the product of the area of piston 44 facing away from the injection jet times the pressure in cylinder 28, less the product of fuel pressure in chamber 17 times the area of the projection of the annular portion 48 within the fuel chamber 17 on a plane perpendicular to the axis of the shaft 47. This net force may be adjusted both by varying the pressure in cylinder 28, and by varying the fuel pressure in fuel chamber 17. 7

Electric current to the heaters is turned on so as to avoid freezing of fuels in the pump if fuels are used which have a melting point higher than ambient temperatures. Lubricant flow, and coolant flow are also started at this time.

To begin the cycling action of the injector, frequency control valve 15 is opened. The accumulator and fuel chamber will then begin to fill with fuel, and the pressure therein will rise. The elastic accumulator begins to yield, and chamber 81 expands, thereby permitting the build-up of both pressure and volume therein. The upper limit of the pressure is that maintained in the fuel supply line on the supply side of the valve.

As the pressure builds up in the accumulator and fuel chamber, the net force tending to seat the pintle assembly on the shoulder 50 decreases. So long as the force on the piston in cylinder 28 is greater than the force tending to unseat the pintle, the injection jet remains closed. When the latter force is slightly greater, the pintle assembly will be unseated. At this moment, the central part of the tapered seat portion 48 becomes exposed to pressure in the fuel chamber, and the unseating force is increased.

This increased force causes the pintle to snap away from the jet.

When the pintle assembly is unseated, some of the fuel stored in the accumulator can flow to the injection jet, along with the quantity of fuel which passes through the supply line 14 during the period the jet is open.

The entire tapered seat portion 48 remains exposed for a time, because the pressure in chamber 17 does not fall suddenly. This results from the fact that the injection jet opening is relatively small compared to the size of the conduits 12.

This fuel ejection, being that of pressurized fluids escaping from a chamber after a quick valve opening, is in a burst. However small the injection jet may be, it still permits fuel to escape more rapidly than the frequency control valve 15 permits fuel to enter. Therefore, when some of the fuel accumulated by pressurizing the accumulator leaves the accumulator, the pressure therein falls so that the force resulting from pressure in the cylinder 28 can move the pintle assembly to close the jet 19. The described cycle then automatically starts again.

It will now be understood how the frequency of pulsation is determined by the valve 15. The accumulator must be charged along with the fuel chamber 17. The pintle assembly does not operate before the pressure reaches some predetermined value. This charging takes a finite length of time, during which period the pintle assembly closes off the injection jet. The more open the valve is, the more quickly the pressure will build up in the fuel chamber. Thus the rate of flow through valve determines the frequency of pintle operation (assuming a constant pressure in chamber 28). The frequency adjustment is as simple as turning a valve.

The quantity of fluid in each pulsation is determined by the pressure in the cylinder 28, which in turn depends on the setting of valve 89. This pressure creates the force which tends to hold the pintle assembly in its down position. The storage limits of the accumulator, plus the amount of fuel replaced to the system while the pintle assembly leaves the jets open will determine the range of volume released by an individual burst. The volume built up in the accumulator and the pressure therein are roughly dependent upon each other in the flexible type.

of accumulator shown. If the pressure in cylinder 28 is high, then the accumulator pressure must be high to overcome it. This means that a greater volume will be stored in the accumulator while the pressure is being developed. Conversely, less pressure in the cylinder results in a lesser pressure and volume in the accumulator. At least a part of the additional increment in the accumulator passes through the jet at each burst and thus the quantity of fuel in a burst is partly determined by the pressure in cylinder 28.

Quantity control by the use of the spring-loaded device of Fig. 10 is the same as that just described, except that the compressibility of the spring and the amount of its preloading are substituted for the fluid pressure in cylinder 28. The spring selected should be of such characteristics that its resistive forces to the rise of the pintle do not build up with excessive rapidity, as it is compressed. Such an excessive rise would diminish the snap action of the pintle when lifted off the jet seat by increasing the force tending to seat the pintle assembly. A fluid pressure in cylinder 28 may be maintained constant, thereby exerting a constant downward load on the pintle assembly. For this reason, a pressurized gas is preferred to a spring.

This invention thus provides an automatic self-contained pulse type injector mechanism with one moving part. The actuating force may be the fuel pressure which is necessary for any fuel system, or some other convenient source of force. With so little in the way of moving parts, the device may be adapted to handle troublesome fuels such as molten lithium, as well as other difficult substances. The controls are simple and the fluid supply to the quantity control means (when used) exists only as a pressure reservoir, from which there is little or no consumption.

It will be appreciated that my invention is useful for the pulsating injection of fluids, including both liquids and gases, and is not limited to liquid injection.

My invention is not to be construed as limited to the particular embodiments illustrated in the drawings and described in the description, which are given by way of illustration rather than of limitation, and the invention is not limited except in accordance with the scope of the appended claims.

I claim:

1. A pulse type injector pump comprising a body having a fuel chamber, a fuel inlet to the chamber, a fuel injection jet from the chamber, and a shaft housing; a pintle assembly comprising a shaft having a longitudinal axis disposed in the shaft housing so as to be axially slidable therein and projecting into the chamber and toward the fuel injection jet said shaft having a cross-section perpendicular to its longitudinal axis which has an area larger than the injection jet, whereby the shaft can close the injection jet in one position of the pintle assembly; means for forcing the pintle assembly toward said one pintle position; an accumulator discharging into the fuel inlet; a fuel conduit interconnecting with the accumulator; and frequency control valving means in said conduit to regulate the flow of fuel to the accumulator and fuel chamber; the shaft being proportioned in size whereby the area of a projection on a plane perpendicular to the longitudinal axis of the shaft of the areas of the shaft facing the injection jet and which are within the fuel chamber and exposed to fuel pressure when the pintle is in said one pintle position is greater than a projection on the same plane of areas of the shaft which face away from the injection jet and which are exposed to the same conditions when the pintle assembly is in said one position; whereby opening of the frequency control valving means permits fuel pressure and volume in the accumulator and fuel chamber to rise, thereby lifting the pintle assembly from the aforementioned position and permitting discharge of fuel through the injection jet, whereupon said discharge causes the pressure in the fuel chamber to fall, and the pintle again closes the injection jet.

2. Apparatus according to claim 1 in which the means for forcing the pintle assembly to said one pintle position comprises springing means.

3. Apparatus according to claim 1 in which the means for forcing the pintle assembly to said one pintle position comprises a cylinder in the body, a piston on the end of the shaft away from the injection jet and disposed in the cylinder and valving means for regulating fluid pres sure within the cylinder and upon the piston.

4. Apparatus according to claim 1 in which the accumulator has springing means for resisting accumulation of fuel.

References Cited in the file of this patent UNITED STATES PATENTS 2,283,725 Eichelberg May 19, 1942 2,297,421 Lorenz Sept. 29, 1942 FOREIGN PATENTS 611,604 France July 12, 1926

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