US2414617A - Pressure and temperature responsive fuel metering and injection pump - Google Patents

Description

7- c. E. SUMMERS PRESSURE AND TEMPERATURE RESPONSIVE FUEL METERING AND INJECTION PUMP Filed Aug. 14', 1943 3 sheets-sheet 1 R w m m w w W I s a. B E L O. Y B 3 mm 1 o ATTO RN EYS okiwt .wski E C. E. SU AND TEMPERA TERI 2,414,617 UEL 3 Sheets-Sheet 2 F E P I SM .NU P PM S s 09 E RR II T E O M MT Jan. 21-, I947.

PRESSURE NE N6 AND I Filed- Aug.

0 o o o o 0 H INVENTOR. 'GALEB E. SUMMERS BY Jan. 21, 1947.

C. E. SUMMER PRESSURE AND TEMPERATURE RESPONSIVE FUEL METERING AND INJECTION PUMP Filed Aug. 14, 1943 3 Sheets-Sheet 3 o v 4% FIGA.

35 43A 4IA INVENTOR. CALEB E. SUMMERS ATTO RNEYS Fate ted Jinn. rear stares PRESSURE AND TEMPERATURE RIEIPN- EEWE FUEL ME'K'E EUIMIP RING AME) lENJLE C'EIUN 4 illaiins. l

The present invention relates to multicylinder internal combustion engines, and more specifically to means for supplying fuel to the several cylinders.

As is well. known, the supplying of fuel to engines from a conventional carburetor may be accompanied by a number of difiiculties such as unequal distribution, mixture variation due to changes in temperature and barometric pressure and others.

It is among the objects of the present invention to overcome such difficulties by providing means for supplying fuel to the individual cylinders by injection of finely atomized liquid fuel under high pressure and automatically varying the amount of injected fuel in accordance with load, temperature and barometric pressure.

Another object is to provide a fuel metering means which provides substantially equal distribution to the several cylinders.

Another object is to provide fuel supply means which automatically adjusts the amount of fuel atomized into the cylinders to accord with the amount of air admitted thereto.

Another object is to provide a fuel metering means which imposes no coming air charge.

Another object is to provide a fuel supply pump in. which the body may he made of a material having a high coefiicient of expansion and plungers of a material having a relatively low expansion rate, so constructed that extreme variations in temperature do not substantially change the clearance between the plunger and its sleeve.

Another object is to provide a high pressure fuel pump in which oil pressure lubrication is maintained around the plungers.

Still another object is to provide a fuel pump in which the clearance between the plunger and v the bore is automatically generated by forcing a plunger into a slightly undersized soft-metal lined bore.

Other objects and advantages will be apparent to those skilled in the art upon reference to the following description and the accompanying drawings in which Figure 1 is a side elevation, partly in section, of a fuel pump constructed in accordance with the present invention.

Figure 2 is a top plan view of the same with part of the cover broken away.

Figure 3 is an end elevation thereof.

Figure 4 is a, section on line t-t of Figure 1 of a part of the cam shaft.

Figure 5 is a detail view of the bellows-actuated shaft.

Figures 6 and 7 show respectively a side eleva tion and a section of a preferred cam construction for large units.

in the drawings, the fuel pump is indicated as consisting of a closed casing of two parts, the lower portion to housing some of the working parts and the upper portion comprising a pair of cylinder blocks ii and MA, and a sealing cover it, and having the other working parts.

The cylinder blocks, each containing one half the number of pump cylinders, are shown oppositely arranged in the same plane, so that the pistons for all of the cylinders may be actuated from a single actuating shaft. It will be under stood that to adapt this device to various motors restriction on the inand services, the pump cylinders here shown up posed, may be arranged in line in V form or radial.

Only one cylinder and piston is shown in detall, but any desired number may be used, de-

pending upon the number of engine cylinders to be served. In the present instance, the number of outlets shown in Figure 2, indicates a total of twelve.

As shown in Figure 1, each of the cylinders it is lined with a sleeve iii provided with annular reliefs iii on the inside and pressed into place in the casing ill. The arrangement of the reiieis ii and in staggered relation and slightly overlapping as shown, permits the use of a rous metal for the piston and sleeve and a body of a, light alloy of a much higher coefficient of expansion, and still maintain the small piston clearance even under extreme temperature changes. The outer ends of the cylinders in are shown as being closed by a cylinder head ill providilng for each cylinder a pump chamber it into which fuel is drawn from a common supply past a disc valve 2il'tensioned against its seat by a suitable spring 2 5. From the chamber 2! the fuel is forced through outlet 25 controlled by valve 26, the latter being resiliently held in its seat by a suitable spring 2?.

Operating in each of thecylinders iii or more correctly, sleeve is, is a piston lid, and since a minimum clearance between cylinder and piston must be had, it is preferred to coat, preferably by plating, the inside of the sleeve with ,a relatively soft bearing metal such as cadmium, tin or silver, to provide an inside diameter a few tenths of a thousandth of an inch less than the diameter of the piston. It should be understood, of course, that the piston should be polished and ,by suitable bearings engine.

4| for a cam 33,

indicated for a second cam 33 (see Fig. 4)

- portion and a 3 straight, so that when forced into the plated sleeve, a substantially perfect fit is obtained.

For each of the pistons 3|! is'provided a rather strong spring 3|, suitably anchored to a stationary part of the cylinder block and biased to move the piston on its outward or intake stroke, while the rearward end of each piston 30- is provided with a roller 32 cooperating with a cam 33 during the inward or pumping stroke, the cam providing the actuating force,

The cams 33 are fixed to a shaft 35 shown in Figure ,1 as tubular, said shaft being supported 33A, Fig. 2, said shaft being driven at half engine speed (by suitable means, not shown) and mounted between the cylinder blocks H and HA, each cam actuating a piston 30 in one cylinder of block II and one in the aligned cylinder in block HA.

The earns 33 are of course so located radially upon the shaft 35 andthe pump outlets 25 so connected as to accord with the firing order of the The mechanism thus far described, in its actuation, will deliver at each of the strokes of the pistons, maximum amounts of fuel, so in order to vary the delivery, the pump is provided with means for varying the length of piston stroke and such means, in the present invention, is also constructed and arranged to cause such variation in accordance with the" engine load and also in accordance with variations in temperature and pressure.

This varying or regulating means is shown in Figures 1, 2 and 4, and consists of a'pair of other cams 40, 4|, arranged adjacent each of the earns 33 and movable around shaft 35 so as to block at the proper point the movement of the pistons 30 outward of the cylinders on their intake stroke, the shoulder 30A contacting the cam 4|, at any point from no stroke to full stroke, depending upon the angular position of cam 4|. Thus an amount of fuel less than the maximum is drawn into the cylinder, at the point-at which the piston movement is arrested and consequently the incoming fuel charge, being determined by the con-, ditions of load, temperature and pressure existing at the time. These other cams are mounted loosely 'on the shaft 35 and are shown at 40 and a second pair 42 and 43 being Each of the cams 40 to 43, consists of a cam bearing portion 40A to 43A (see Fig. 4) and on each cam portion is provided an ear 40B.

Surrounding the bearing portions 40A, etc. is a sleeve 45 carrying at each end a pair of arms 45A and 453, each carrying an car 450, and a second pair of arms 45D and 45E, each of which carries a stop lug 45F. The ears 40B and 45C extend outwardly from the cams 40 and 4| and serve as abutments for springs 45 which hold the cams 40, etc. resiliently against the stops 45F. Thus it will be seen that when there is a sudden demand forv power, the bellows easily rotates the cams 40-, etc. even though some are acting on the plungers, for the movement is down hill. When less power is needed, the bellows takes a position compressing the springs 45 until the cam 33 lifts the plungers.

As may be noted from Figure 4, a single sleeve 45 is arranged to coact with the movable cams 40, etc. for two of the cams 33. This means that, in the pump illustrated with twelve cylinders, there will be three sleeves 45.

Each of the three sleeves 45 is provided with but it should be understood that 4 an actuating arm 5|! and each arm 50 connected by a suitable link'5l to a crank arm 52 fixed upon a rotatable shaft 53. The shaft 53 is in turn rotatable through arms 54 connected through link 55 to the bellows 60, of which two are shown, one or several :nay be used without departing from the invenion.

The sealed bellows 50 is mounted within the lower part of the housing l0 and is filled with an inert gas. In order to make the bellows more sensitive to outside temperatures and also to reduce the volume of its gas contents so that the maximum expansion will not overstrain the metal of the bellows a cylindrical displacement member 5| is used to seal the bellows. This member 5| is integral with the base 52 of the sealed bellows 50 and is sufficiently large to substantially fill the bellows, leaving only the bellows ribs and a small part of the remaining interior for the inert gas.

. The member 5| is of course closed at its inner end but is open at the outer end and thereby provides a large surface susceptible to the influence of outside temperatures and, since the sealed in gas is dispersed in a thin layer on the outside of member 5|, it receives and reacts quickly to any temperature change outside or inside of housing l0.

The bellows 50 is mounted in the housing I a in a cylindrical guide 53 and since the housin is filled with oil, well above the guide, the latter is perforated as shown, to permit free movement, of the bellows. Further in order to protect the bellows against wear, bearing rings 54 may be provided.

Iii-order to submit the bellows 50 to the influence of load conditions, the housing i0 is, as stated above, sealed and provided with a nipple 10 or other connecting means whereby theinterior of the housing may be connectedto the intake manifold of the engine.

In the operation of the device, when the conditions of load and temperature indicate a full charge of fuel in the respective cylinders of the engine, the cams 4|! and 4|, and the corresponding cams will be in approximately the position shown in Figure 1, that is, they will not interfere with the movement in and out of the pistons 30. Consequently, each piston 30 draws in and forces out a full charge. When, however, a part throttle and 'a high outside temperature, or either condition exists, the bellows 50 will expand and move the cams 40, 4|, etc. into position to blockmore or less the outward movement of pistons 30 with a consequent pumping of only a part charg of fuel.

It is now apparent that the inert gas sealed within the bellows 50 is subjected to the same temperature andabsoiute pressure as the charge entering the cy' derand therefore its density is proportional to the density of the air change. If, therefore, we have a measure of the volume of charge entering a cylinder, the position of the bellows acting through selected lever ratios and a proper contour of cams 40- could be made to control the stroke of the plunger 30, to give tion of the rate of the spring 62A, provided withproper stops or controls, will give a closely approximate correction for the variation in volumetric efllciency of an airplane engine from level to the stratosphere.

Since the method of controlling the rate of fuel discharge is by arresting the pump plunger at any required point in its intake stroke, it is desirable to make that the velocity of the plunger 30 is substantially uniform throughout the stroke so the shock of such arrest and also the shock when the cam 38 again contacts the roller 32 for the discharge stroke, will be uniform and at a minimum. In order to cushion such shock, a slight resilience may be provided by making the cams 33 in the form shown in Figures 6 and 7, that is, by forming the cams of sheet metal so that the cam surface is on an overhanging flange capable of a slight give. The uniform speed of the plunger an the sudden stop at the end of the stroke, gives uniform atomization and a minimum drool.

The relative proportion of the 360 33 that are used for the maximum stroke and the plunger 30 is to of the cam discharge maximum intake stroke of the be determined for best results in each service. Preferably the discharge stroke shall not be'more than 120" which leaves 240 for the intake stroke which is relatively slow and easy for the fuel to follow.

It should be noted that with the extremely small clearance of pistons 30, very high pressures will, be developed in the fuel delivery to the the central relief l8 through the inlet I 8K.

the contour of the cam 33 such the parts are inposition to supply a partial charge, the injection is somewhat delayed and such delay favors stratification, and thereby facilitates firing of the lean charge.

I claim:

I manifold of said engine, a body of oil in said It should further be noted that due to the slope of the cams 40, 4|, etc., they will have a tendency to move to full charge position and. therefore, the direction of rotation of shaft 35 should be such as to tend toneutralize this by the friction of the parts.

One of the many advantages to be derived from the use of the present device lies in the fact that it acts also as a timer for the fuel injection. When housing. an expansible an contractible element CALEB E. SUMMERS.

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