US2421475A - Fuel feeding system - Google Patents

Description

June 3, 1947. L. BEEH FUEL FEEDING SYSTEM Filed Sept. 5, 1941 INVENTOR OU/5 @EE/ my i mi?? Patented June 3, 1947 UNITED STATES PATENT OFFICE FUEL FEEDING SYSTEM Louis Beeh, Springfield, Mass. Application' September 5, 1941, Serial No. 409,663 (cl. 12s- 139) 12 Claims. y 1

This invention relates to a fuel feeding system for internal combustion engines of the solid injection type'. In engines of the type to which the invention relates an injector directed into the combustion space of the engine is provided with an injection valve which is opened in response to the increasing pressure of. the -liquid fuel supplied thereto by a suitablejfuelpump and is closed by the action of a heavy spring or other resilient means in response to a reduction of pressure in the fuel supply line. This de` crease in injection pressure is normally the result of the opening of a spill valve or by-pass passage which opens into the pressure chamber of the pump and thereby immediately and sharply reduces the pressure in this chamber. Because of the high pressures of the order of 4000# per square inch in the Afuel line there is a reaction of this pressure in the direction of the reduced pressure in the pump chamber and a resultant tendency ofthe fuel in the line to reverse its direction of flow 'and move in the direction of the pump chamber. The reaction causes the discharge valves between the pump chamber and the fuel line to close sharply s 'that the fuel in the injection line is still under a'high pressure.

Reactions are set up due to the inertia of the moving column of fuel and due to the natural resilience 'of the supply line, such that reversals of the pressure wave in the supply line are set up so that the wave again moves in the direction of the injection valve, tending to open the same slightly and causing a slight dribble at the nozzle orice.

The fuel so improperly atomized and improperly timed with respect to the engine cycle is not properly consumed andv is therefore objectionable from the standpoint of thermal eiliciency, but it also tends tc carbonize around the nozzle orifice and is therefore also objectionable from the point of view of mechanical efficiency.

In some instances these pressure waves travel back and forth several times in the fuel line, causing no t only secondary Lut tertiary injections.

There have Aheretofore many attempts made to overcome the above-mentioned difficulty and prevent thisvdribble at the fuel nozzle. The most common of these is to provide a skirt 'on the discharge valve of the pump. which skirt upon the closure of the valve functions as a piston or plunger, moving in the direction of the pump chamber, and is therefore effective to increase the total volumetric capacity of the fuel line and other connections between the pump chamber and the injection nozzle. Such a system is effective to reduce the static pressure within the fuel line and therefore avoid any oozing of y fuel from the nozzle due to this static pressure.

Such a system, however, is not effective to reduce the dynamic forces which cause the secondary and tertiary injections which are due to successive reversals of the direction of flow in the line, which occur upon the final closure of the discharge valve whether provided with ya withdrawal skirt or not, due to the piling up of the pressure in the vicinity of the discharge valve and the reaction of this pressure back through the line in the direction of the injection valve.

It is among the objects of the present invention to overcome the above-mentioned diflculties and prevent the violent oscillations of theA iuel remaining in the fuel column.

The secondary and tertiary injections abovedescribed leave the fuel lines, if they are not all of the same capacity, under varying residual pressures and cause the next succeeding injecboth the beginning and the end of the injection,

thereby providing a smoother engineoperation.

The above and other objects and features 0f the invention will be apparent to those skilled in the art from a consideration of the following detailed description vtalren-in conjunction with the accompanying drawings in which:

Fig. 1 is a vertical section of a portion of the fuel feeding device constructed in accordance with the present invention and also showing a portion of the internal combustion engine to which the device is connected.

Fig. 2 is a vertical section through a portion of a-fuel feeding device showing a modied form of the invention.

Fig. 3 is a view similar to Fig. 2 to show a further modification.

Referring to the drawing, reference numeral I roundingthe'valve on the permit the escape rected into the combustion space 4. The nozzle orice 3 is closed by a valve 5 of conventional construction and having as usual a shouldered portion 6 which is adapted to be acted upon by the pressure of fuel supplied thereto by way of the supply line 1 to move the valve in an opening direction against the action of the spring 8.

luel is supplied to the injector .2 by means of a pump 3 havinga plunger I0 mounted to reciprocate in a cylinder II and adapted to uncover a supply port 12in its lowermost position whereby fuel from the feed chamber I3 may ilow into the pump ch mber I4 when piston I0 is in the position show'n in the drawing, while the upper end of the cylinder II is closed by a plate I5, which plate is provided with a discharge orifice I6 provided in the central portion thereof. The plate I=is held in position against an interior shoulder in the pump body I1, and also against the upper end of the pump cylinder I I, by means of a bushing I8 which is provided with external 'threads coacting with'internal threads in the upper end of the pump body I1 to the end that an annular boss I9 upon the end of the bushing I8 will press upon the peripheral portion of the plate I5 when the parts are in the position shown.

The bushing I8 is provided with a central cylindrical bore 20 in which a discharge Valve 2| having a cylindrical sleeve portion 22 is adapted to reciprocate, being biased in the direction of plate I5 by the spring 23. The lower end of the valve 2I is provided with an annular bossf24 of considerably less external diameter than the external diameter of the sleeve portion 22. The annular boss 24 is adapted to seat upon the plate I5 in closing relation to the orifice IB sothat when the valve is in the closed position, as shown. a relatively small area thereof is exposed to the pressure within the pump chamber I4, while an additional ar'ea is exposed to the pressure of the fuel in the annular discharge chamber 25 surdischarge side of the oriflce'f- I-E.1"

The chamber 25 communicates by way of passages' 26`in the bushing I8 with an annular chamber 21; which chamber is directly connected to the fuel supply line 1. For convenience of construction'the annular chamber '21 may be formed 4 I0 approaches the end of its discharge stroke, a helical lip 34 on the end of the plunger II) uncovers the by-pass port 33, permitting the fuel from the pump chamber I4 to flow into the bypass chamber 35 and thence back to the fuel supply tank by way of pipe 36; thus there is a sharp reduction in the pressure within the pump chamber I4 and within the discharge chamber 25. The pressure in the supply line 1 is sharply reduced, the injection valve 5 tends to close and the fuel in the supply line '1 which was formerly owing at high velocity toward the injection valve now tends to iiow in a reverse direction toward the fuel pump. This -reversal of flow sets up a pressure wave in the direction of the pump which, if the discharge valve 2I were a conventional check valve, would tend to cause the valve to seat sharply due no t only to the action of the spring :23 but also to the dynamic pressure of the fuel in the supply line. This would be true regardless of whether or not the check valve were provided with a withdrawal skirt.

By the present construction the reversal of flow in the supply line 1 has no tendency to close the discharge valve but on the contrary acts upon the valve to move the same in an opening direction so that the pressure wave tends to become dissipated through the discharge orice I6, the pump chamber I4 and thence to the by-pass port 3-3. Thus the reversal of :dow in the fuel line does not build up a pressure on the discharge side of the valve which could possibly react back in the direction of the injection valve and cause a secondary injection. It will be understood that the spring 23 being weaker than the spring 8,-any pressure wave present in the fuel line and hav- -ing sufficient force to open either of the valves,

will necessarily dissipate itself through the discharge valve of the pump ratherl than through in a block 28 separate from the bushing I8 and rmly attached thereto in a manner hereinafter to be described. h

The valve spring 23 is adjustable by means of a screw plug 29 which extends through an internally and externally 'threaded nipple 30 which projects from the upper end of the bushing I8. The screw plug 29has a central passage 3l to of any fuel which leaks around the valve 2l into the cylindrical bore 20. A nut 32 coacting with the external threads on the nipple 3D holds the block 28 firmly in position.

In the operation of the device when the parts are in the position as shown, with the plunger lllin its lowermost position, fuel is supplied under some pressure by Way of the supply chamber I3, and the pump chamber I4 is filled with fuel. As the plunger I8 moves upwardly the intake port I2 as well as the by-pass port 33 are closed by the upper edge of the plunger II] and further upward movement vof the plunger I0 places the fuel under .suiiicient pressure to cause the same to lift the the injection valve of the engine.

Referring to Fig. 2 which shows only the parts directly associated with a modif-led form of the discharge valve, it will be obvious from the drawing that the construction and operation of this form is closely analogous to the form shown in Fig. 1 except that a small valve 4Il is provided in the discharge valve 4I and is adapted'to control an orifice 42 which extends through the face of the discharge valve 4l. As in the prior construction a spring 43 biases the discharge valve 4I in a closing direction' and a spring 44 surrounding a stem 45 on the valve 40 normally maintains the latter valve in a closed position. A set screw 46 is mounted for adjustment in the upper closed end of valve chamber 41 and projects downwardly therefrom to contact with the' upper end of the stem 45 of the valve 40 whenever the discharge valve 4I has been lifted to a point slightly below the uppermost limits of its opening movement.

The operation of the form shown in this figure is similar to the operation of the form shown in I Fig. 1 since it will be understood that fuel placed under pressure by the pump plunger will lift the discharge valve 4I from its seat and cause fuel to ow to theengine by Way of passage 48, the cutoif of the fuel supply and the prevention of oscillations of fuel in the fuel line being effected in the same manner. The form here shown, however, has the additional advantage that at high speeds the valve 4I moves upward further in its opening direction than at low speeds and as these high speeds are attained the stem 45 of the valve 40 contacts the set screw 46, thereby Ipermitting a slight flow of fuel through the passage 42 into pressure stroke thereof tends `to increase as the speed increases. This is particularly true in connection with pumps of the type in which the quantity of the fuel supplied by the pump is controlled by a helical lip on the end of the plunger, which lip 'varies the time of opening and closing of the by-pass passages of the pump to the end that angular movements of the pump plunger will cause the by-pass passage to be opened sooner or 'later during the discharge stroke of the pump plunger and accordingly supply a smaller or greater quantity of fuel to the engine for each working stroke thereof. In all such constructions where one or more of the ports of the pump are positioned in the side walls of the pump cylinders and controlled by the plunger, the leakage around the plunger into these ports will be greater when the pump plunger is moving slowly thanit will be when the pump plunger is moving at high speed. For this reason the pump will tend to supply a greater charge at high speed for cach stroke thereof than it will supply when operating at a relatively low speed.` This increase in the unit charge of fuel supply at high speeds is' the reverse of the relationship that is actually required inasmuch as a slight reduction in the unit charge for high speeds is desirable. l;

By the form of the invention disclosed .in Fig. 2 an automatic compensation is made for the unit charge supplied by the pump at high speed since at low speed the discharge valve 4| ds not move upwardly far enough for the stem 45 to contact with the set screw 46 and therefore the full charge for any given setting of the control rod of the pump is supplied to the combustion-space of the engine. However, as high speeds are attained the valve 4| moves further in its opening direction until the valve 40 is opened by contact of the end of stem 45 against the set screw 46 and a slight compensating leak-v age is thereby permitted during the short period in which the discharge valve 4|` is in its uppermost position. t A

It will also be seen that this form of the invention provides a safety escape in the event that the fuel nozzle 3 should become clogged or the injection valve 5 should become stuck so that fuel cannot be discharged into the clearance space of the engine, for in either case pressures cannot be built up in the fuel line 'l such as would cause breakage of the pipes or connections because under such conditions-the valve 4| would be forced to its uppermost position, causing the valve 40 to open and relieve the pressure in the fuel line by way of the orifice 42, the-valve chamber 41 and return passage 49.

Referring to the form shown in Fig. 3 it will be seen that the construction is similar to that shown in Figs. 1 and 2, except that the discharge valve 50 is provided with an enlarged shouldered portion 5| of greater diameter than the sleeve portion 52 of the valve and that this enlarged portion on the Avalve makes a loose sliding t with a slightly enlarged portion 53 'of the cylindrical bore 54. As in the construction previously described, the valve 50 is adapted to close the discharge port 55 ofthe pump chamber i6 to permit the now of fuel to the engine during the discharge stroke of the pump plunger. the fuel passing by way of vertical passages 5l and cross passages 58 to the discharge nipple 59 which is connected to the fuel supply lin'e leading to the engine `cylinder asndisclosed in Fig. l.

However, in this construction the valve chamber 60 is connected directly to the fuel supply line by way of an orifice 6| connecting with cross passage 58 at a point which is preferably in `line with the passage through 'thedischarge nipple -59 which is connected to the fuel supply line in the usual manner. In this construction the pressure in the pump chamber 56during the pressure stroke of the pump plungerlifts the valve 50 against the yaction of spring '62, permitting fuel to flow to the engine. Since, however,.the surface area in the rear of the valve which is exposed to the pressure in the fuel line is almost but not quite equal to the area exposed to the pressure on the. face of the valve, the upward movement of this member is maintained within predetermined limits even though the spring 62 is not fully compressed. If now the pressure on the lower face of the valve 5U is decreased by reason of the opening of the spill valve of the pumpplunger during the discharge stroke thereof, then the pressure upon the rear face, being momentarily greater, will act to move the valve in a closing direction. The same movement, however, tends to withdraw the fuel from the region in the rear of the valve and adjacent the fuel supply line 'l so that the first movement of any oscillation or reversal Vof direction of ow in the fuel supply line is in the direction of the valve chamber 60, Whereas the displacement in the opposite direction'tends to displace the fuel in the direction of the pump chamber 56 during the closing movement of the valve. Should the valve reach its full closed position during the period in which there is a continued surge of fuel from the line in the direction of the pump,

. this surge will first tend to dissipate itself in the valve chamber 60 and thereafter surge as'a pressure wave in the direction permitted by cross passage 58 and verticalpassages 51, where the pressure Wave having access to a slightly greater area or pressure surface will tend to lift the valve slightly and dissipate itself through the pump chamber 5B. In this structure violent oscillations of the valve 50 are prevented while at the same time oscillations of the fuel within the fuel supply line which normally result in secondary and tertiary injections are dissipated.

It will be apparent that in each of the embodiments of the invention free communication is permitted through the system betweenA the seat of the injection valve 5 and the by-pass passage 33 the instant this passage is opened by the lip 34 during the upward movement of the pump plunger. No motion of any mechanical part is required to eiect or complete this communication since the only valve between the pump and the injection valve is, and remains, in open position at this time. This is important since the desired reduction in the static pressure of the line must take place in a period of a few microseconds.

Each of the embodiments of the invention also provide a construction in which. a constant residual pressure is maintained in the system yafter the pressure has been reduced to a predetermined minimum. Thus, in contradistinction to some prior systems which sought to obtain free communication between the pump and the nozzle at the instant injection is terminated by providing a continuous communication at all times, the present invention permits such free communication at the desired instant yet prevents communication at times when undesired,

such as during the suction stroke of the pump. Communication between the pump and the rest of the system during the suction stroke would permit fuel to .be withdrawn from the line to the pump instead of from the suction side of the pump. The pump would thus be totally ineffective as a metering device. The maintenance of the residual pressure in the line is desirable to prevent rapid evaporation of fuel in the nozzle which is heated from the combustion'space of the engine, and the formation of vapor pockets the portion of the line close to the nozzle, as

the inertia is overcome and the fuel accelerated toward the pump. By providing a reduction in volume in the region of the greatest reduction of pressure the pressure differences along the line are less and the ram effect greatly reduced. Furthermore, since the valve may open again after its initial closing 4in response to pressure in the lin'e any secondary surges in the line are dissipated through the pump in the same way as the initial pressure drop. For this purpose a very slight opening of the valve suiiices. In most prior art systems the drip prevention means has tended to increase the surging of fuel in the line rather than diminish it.

It will also be observed that since lthe closing movement of the discharge valve is against the.

residual pressure of the line the valve closes gradually and is not slammed against its seat.

While there have been herein described various embodiments of the invention other embodiments within the scope of the appended claims will be apparent to those skilled in the art from a consideration of the embodiments shown and the teachings hereof. Accordingly it is desired that the appended claims be given a broad interpretation commensurate With the scope of the invention within the art.

Having thus described the invention, what is claimed as new is:

1. In a fuel supply system an injection pump including a pump cylinder, a plunger reciprocative within said cylinder, said cylinder being provided with inlet and discharge ports, means' for relieving the pressure in said pump cham ber in the course of the discharge stroke of said plunger, a discharge valve normally closing said discharge port and operable by the' pressure in said pump to open said discharge port, a fuel supply line leading from said discharge valve, an injector having a nozzle oriiice connected to said supply line, a pressure operated injection valve for closing said orifice, said discharge valve having a pressure area exposed to the pressure in said supply line eiective to bias said valve in an opening direcwhich would also interfere with the accurate tion, whereby the reversal of flow in said supply line upon the release of pressure in said pump acts to maintain said discharge valve in open position to vent fuel from said supply line to the pump side of said discharge valve until the pressure in said line drops to a predetermined value below the pressure required to operate said injection valve.

2. A rue1supp1y system including m comb/ina;- tion a fuel feeding device, a fuel injector, a fuel supply line connecting said fuelr feeding device and said fuel injector, a valve controlling communication between said fuel feeding device and said supply line, said valve having surface area exposed to the pressure in said feeding device when the valve lsin closed position and being operable by the pressure in said device to open communication between said device and said supply line upon an increase in pressure in said device and to close such communication in response to a decrease in such pressure, said valve also having a surface area exposed to the pressure in said line and acting to move said valve in an opening direction in response to a predetermined pressure in said line.

3. A fuel supply system including in combination a fuel injection valve opening in response to the pressure of the fuel supplied thereto and y closing upon a predetermined decrease in such pressure, a pump, a fuel supply line connecting saidpump and said injector, a movable member positioned between said pump and said injector, said member being operable in response to an increase in pressure within said pump to open communication between said pump and said sup-- simultaneously increase the total line in4 proportion to the increase in pressure, means for suddenly relieving the pressure within said pump, and means associated with said movable member for maintaining the same in open position until after a predetermined decrease in the pressure within said supply line.

4. A fuel feeding system including in combination a fuel injection device, a fuel pump, a supply line for conducting fuel from said pum'p to said injector, a valve positioned between said pump and said injector, said valve having a pressure area exposed to the pressure in said pump when the valve is in closed position and also having a further pressure area exposed to the pressure in said line, said areas being effective ply line and to volumetric capacity of said upon predetermined increases in pressure in either said pump or said supply line to move said valve in an opening direction, and resilient means for biasing said valve in a closed direction, whereby predetermined increases in the pressure in said pump cause said valve to open and permit the flow of fuel to said injector and whereby pressure in said line acts in an opening direction on said valve to permit the flow of. fuel in a reverse direction upon the decrease in pressure in said pump, thereby maintaining in said line a predetermined pressure below the injection pressure during periods when the pump pressure is below the injection pressure.

5. A fuel feeding system includingin combination a fuel injection device, a fuel pump, a supply line for conducting fuel from said pump to said injector, a valve positioned between said pump and said injector, said valve having a pressure area exposed to the pressure in said pump when the valve is in closed position and also having a further pressure area exposed to the pressure in said line', said areas being effective upon predetermined increases in pressure in either said pump or said supply line to move said valve in an opening direction, resilient means for biasing said valve in a closed direction, and means to adjust the Dtension of said resilient means, whereby predetermined increases in the pressure in saidl pump cause said valve to open and permit the flow of fuel to said injector and whereby pressure in said line acts in an opening direction on said valve to permit the flow of fuel in a reverse direction upon the decrease in pressure in said pump, thereby maintaining in said line a predetermined pressure below the injection pressure during periods when the below the injection pressure.

6. A fuel feeding system including in combinapump pressure is tion a pump-an injector, a fuel supply line between said pump and said injector, a pressure responsive valve between said pump and said injector controlling the ilowof fuel through said line and operable in one direction to open communication between said pump and said injector, and means associated with said valve for relieving the pressure in said line when said valve approaches the limit of its opening movement.

7. A fuel feeding system including a pump, an

injector, a fuel supply line between said pump and said injector, a pressure responsive valve between said pump and said injector controlling the now of fuel through said line and operable in one direction to open communication between said pump and said injector, means forming with said valve an auxiliary chamber in restricted communication with said line, whereby upon the increase of pressure upon the face of the valve the volumetric capacity of said auxiliary chamber will be proportionately decreased and .upon decreases of such pressure the volumetric capacity of said auxiliary chamber will be increased in proportion to the decrease in pressure in said line.

8. In combination, a fuel'pump having a pump chamber, a fuel supplyline leading from said trolling ,10. The combination, with a fuel injection system of the type having a fuel injection pump, a closed fuel injection nozzle and a fuel supply-line connecting said pump and nozzle; of a valve con- -communication between said pump and said nozzle, said valve opening in response to the pressure on the pump side thereof, and also open'- ing in response to pressures above a predetermined value in said line between said valve and said nozzle said predetermined value being less than the pressure required vto open said nozzle.

1l. In a system of the type including a high pressure liquid pump, a pressure operated atomizing device, and a supply line connecting said pump and said device, the combination of a valve controlling communication between said pump and said device, means to `suddenly relieve the pressure on the pump side of said valve, said valve opening in response to pressure on the pump side thereof and remaining open upon the relief of the pressure on said pump side until the pressure between said valve and said nozzle falls to a predetermined value below the pressure required to operate said atomizing device.

l2. In combination a high pressure liq'uid pump, a pressure operated atomizing device, a supplyl line providing .a passage between said pump and said atomizing device, a valve controlling said passage, said valve beingppened in response to the pressure in said pump, means to suddenly relieve the pressure on the pump side of said valve, and means to maintain said valve in open position upon the relief of pressure onsaid pump side thereof until the pressure'between said valve and said atomizing device falls to a predetermined value below the vpressure required to f operate said atomizing device.

pump chamber, a valve controlling communican tion between said chamber and said supply line, said valve being opened in response to pressure in said pump chamber, means to suddenly relieve the pressure in said pump chamber, and means to maintain said valve in open position after the relief of pressure in said pump chamber to vent fuel from said line to said chamber until the pressurein said line drops to a predetermined value.

9. In combination, a fuel pump having a pump chamber, a fuel supply line leading from said pump chamber. a valvecontrolling communication `between said chamber and said supply line, said valve being opened in response to pressure in said pump chamber, means tosuddenly relieve the pressure in said pump chamber, and means responsive to the pressure in said line for holding said valve in open position to vent fuel from said line to said chamber until the pressure in said line has been reduced to a predetermined value.

LoUIs BEH.

REFERENCES CITED ,The following references are of record in the iile of lthis patent:

UNITED STATES PATENTS Number Name Date 2,211,252 Bremser' Aug. 13, 1940 1,974,851 Hurst Sept, 25, 1934 2,202,761 Fiedler May 28, 1940 1,589,515 Danielsson June 22, 1926 2,007,871 Oldham .1 July 9, 1935 2,247,421 Tabb et al. July 1, 1941 2,033,839 Lawson Mar. 10, 1936 2,019,103 Thege Oct. 29, 1935 1,989,720 Thege Feb. 5, 1935 2,131,779 Zwick Oct. 4, 1938 1,981,913 Fielden Nov. 27, 1934 'FOREIGN PATENTS Number Country Date '60 490,741 Germany Jan. 31, 1930 797,444 France Apr. 27, 1936 Switzerland 138,400 May 1, `1930

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