US2406115A

US2406115A - Charge forming system

Info

Publication number: US2406115A
Application number: US423772A
Authority: US
Inventors: Stephan Fritz
Original assignee: HERBERT G BENZ
Current assignee: HERBERT G BENZ
Priority date: 1941-12-20
Filing date: 1941-12-20
Publication date: 1946-08-20
Anticipated expiration: 1963-08-20

Description

Aug. 20, 1946; STEPHA'N 2,405,115 CHARGEFORMING SYST M Filed me. 20, 1941 4 Sheets-Sheet 1 Aug. 20, 1946, F, STEPHAN- I 2,406,115

' I CHARGE FORMING SYSTEM I Filed Dec. 20, 1941 4 sh t -sheet 2' Align 2Q, figfio I 3 STEPHAN 2,406,115 k CHARGE FORMING SYSiTfER/l Filed Dec. 20, 1941 4 Sheets-Sheet s Au ;2o, 1946; I 2,406,115

CHARGE FORMING SYSTEM Filed Dec. 20, 1941 v 4 Sheets-Sheet 4 I W 2% m *1 WEE I g I; WWI

Patented Aug. 20, 1946 UNITED STATES, PATENT E T' v7 2,406,115 v N g "CHARGE FORMING SYSTEM j I Fritz Stephan, Minneapolis, assignor t o 1 Herbert G.'Benz, St. Paul, Minn.

ApplicationDecember 20, 1941, Serial No. 423,772

scams. (01. 261-37) This invention relates to chargeforming systems for internal combustion engines, and is particularly directed to that type of system wherein the fuel is injected by pressure into the intake manifold of the engine. e

The main object .of the invention is to provide a system for easily and accurately controlling the air-fuel ratio of the engine charge.

A further object of the invention is to provide a system in which th amount. of fuel introduced into the engine charge is variably controlled at will. i

A third object of the invention is to provide a charge forming system in which the pressure of the fuel entering the charge controls the quantity of air introduced and theair-fuel'ratio of the charge, and specifically, to provide a system wherein the pressure of the fuel functions to control the quantity of airand the air fuel ratio by directly controlling the operation of. the air intake throttle valve.- .1

- Another objectof the invention is to'op'erate thethrottle valve controlling the air entering the charge in dependency on air pressure, and

further, to operate such valve in dependency both" on air pressure and fuel pressure.

A further object of the invention is to provide a variable displacement fuel pump forsupplying controlled amounts of fuel to the engine charge.

Yet another object of the invention is to provide means for controlling the fluid pressure of the fuel supplied by the, variable displacement pump to the engine charge. I '3 A further object of the invention is to control the pressure of the fuel suppliedto the engine charge in dependency on pressure conditions within the charge forming system.

Another object of the invention is to provide a fuel injector for introducing fuel into the engine charge under controlled pressure. I The invention will be further understood with reference to an embodiment thereof shown in the accompanying drawings, in which:

Fig. 1 is a front elevation of the charge forming system in combination with an internal combustion engine; g .Fig. 2 is a sectional view of the fuel pump taken on the line 2-2 of Fig. 3;

Fig. 3 is an end elevation view of the unit;

- Fig. 4 is a sectional view of a detail of the p mp u t; I

Fig. 5 is an end elevation view of the unit of the pump;

cylinder fuel pump Fig. 6 is an end elevation assembly of the pump; 7

Fig. '7 is an end elevation view, of the cylinder? end plateunit of the pump; v Fig, :8 is a sectional. View of the cylinderend plate taken on the line 8-8 of Fig. '7;v v Fig. 9 is a vertical sectional view of the Jin jector and throttle unit; Fig. 10 is a side elevation view partly in section on the line IO-JUofFig. 9;. v Fig. 11 isa sectional view taken onthe line I l-l l of Fig. 12 showing the injector unit; and,.

Fig. 12 is an end view of the injector unit. a A charge forming system of-the inventionis adapted for use in combination with varioustypes of internal combustion engines, including marine and aircraftas-well as automotive and stationary engines. It may be employed with-supercharged engines as well as withthe conventional types. In the embodiment shown in Fig. lfthe system. is disclosed in combination with, an engine l of; the Vtype having two banks of cylinders, land 3. Intake manifold 411s provided for conducting the charge to the cylinders which in this type of engine are conventionallydivided into, two groups and fed by a duplicate chargev formingsystem.

' The fuel injection and throttle valveunit. 5

of the invention is positioned at the anterior nd of the'intake manifold 4, and is suppliedwith fuel from pump unit 6 through fuel pipe I.

The fuel pump unit 6 constitutes a variable displacement engine driven .pump which may be. controlled by the operator for the purpose of changing the charge supplied to the engine. For. this purpose operatinglever 694s provided to vary the pump displacement. I j p The pump is of the radial type employing -a plurality of cylinders, and having means for varying the stroke of the pistons.

The pump is' provided with a main shaft-8 having a splined end!) which in the embodiment shown in'Fig. 1 may conveniently be gear driven from the cam shaft gear of engine I. Conven iently the pump isconstructed with frame unit l0 provided with suitable holes I I through which it maybe bolted to the engine. Cooperating with frame unit IE is the opposite end unit [2, the same being connected by bolts [3 and clamping the cylinder-assembly between'the end and frame units.

.- In the embodiment shown the cylinders are rectangular in cross section, beingformedin the cylinder unit l5 show in Fig. 5. The end walls of the cylindersare formed by cylinderend plates View of the page.

V through port il oi end pIa'te' 7 3 l6 and I1. the latter being shown in elevation in Fig. 7.

The pistons l8 slide in cylinders IQ of the cylinder unit and conform closely to the walls of the cylinder as formed by the cylinder end plates and cylinder unit. Each piston I8 is provided with wrist pin 2| journaled therein and slotted to receive. theminturned. ends22 of connecting rods 23.. In the embodiment shownthe'connect ing rods at each side of the pistons are formed in a unit; extending radially from the base-mem;-

bers 24. The base members are pressed on the outer race 25 of the main needle bearing- 265 As shown in Fig. 2, the connecting rod assemblyl works in recesses 2! provided'inendplates lfi and I1.

The eccentric member 28 constitutes the inner 4 [2 of the pump. Thence by coupling 60 and union 6| the fuel passes to the pressure fuel line 1.

The fuel is suitably introduced from the intake valve recess 52 to the appropriate pump cylinders when the respective pistons are at the top of their stroke. A the piston recedes in the cylinder the fuel is drawn into the same until at thebottom of the stroke the movement of main shaftiil closes the=-intake valve and whemthe piston begins its return movement the outlet valve recess 51 0f main shaft '8 meets the appropriate bore 56 to permit the fuel to be forced to fuel line 1. Through the above describedadjustment .ofeceentricimemben 2.8 the piston throw and conrace of' needle bearing 26 and is adjustably mounted on main shaft 8. For this purpose main shaft 8 is providedwith a squared out section!!! received in an'oblong aperture 14' of -eccentric member 28. The 'throw of' 'ecceritric member 28* is" adjusted by'm'ean of-"cam wedge 3.0 which .is biased to'th'e'left-'byspring'3l contained" in "bore 32 of the main"*shaft, as isbest shown .in.Fig."6.' Eccentric mernliu'erifl'i- 'retainedin the "proper 'positi'oxrpn the" main shaft by integral'shoulder 33.

ably. controlled through "pushrrod'34 working in bore 35. of the main' shaftfj The" position of "the push rod is controlled. 'by'themain pump. operating lever 69'" which is keyed to" bushing 3 6 rotatabiy mounted: in member 37 which is threaded intoend unit 12 of the'pump; being-providedwith' a, asket .38" toprovide a fluid"typ'e' closure. Op erating lever 69. is. retained 'on bushing 36- by end "cap 319;. Bushing 36 is internally 'splirred' at 40i'and slidably receives thrustme'mber 4l which is externally splined. Thrust "member 4| i'sf'ex te'rnally threaded at 42 and cooperates with -in-:

ternal,threads."43"of'member 313 "It Willtherefore be; understoodithat' on movement o'fopieratv ing flever 6.! thrust member 40 is -axially moved through-rotation"impartedfthereto 'by'spliningilili f 'pling 49 to annular re'oess"5'0in the cylinder 'en'd platef'lfi. 'From recess 50*"the" fuel passe "into ports f 51"- spacedangularly around member' I-G' in correspondence withtl'i'e cylinders.- li/Iain-"shaft Bfispro ided with intakevalve recess 52: The fuel is received through ports '5 I andi'i conduct ed-by'valve recesses 5'2 to portsf- 53 from which it "Fromthe cylinders the :rum passes through ports' '55 6f the end plate' I li'through bores $6 of end unit I2, ports 53 of end plate l1,to the='out= 1 let'* valve-recess ET' ofmai-nFshaft T 8. -E-Xhaust' r valve-reces 51 leads to an annular recess T58 'in sequently therpump displacement may be varied.

In order to prevent fuel leakage in the driven 'end-ofimain'shaftl seal 62 carried by rin 63 is threaded into the frame unit HI. Any leakage pa'st seal 62 is retainedin'chamber 64 formed by member 65 which is pressed into mounting frame I 0- against" bushing-"66E Annular chamber 64 may bedrainedthroug'h bore fil and'" d'raih' plu'g68.

'rhe rue1 supplied toline-l 'fronr'the pump-unit 6 is supplied to two injectorunits "'10 for intros.

ducing'the fuel to passages: l-llllofthe throttle and injection unit '5 for-admixture" therein into a charge with air.'

As shown in Fig. ll the injector unit '10- comprises a base member'll} adapted to'be' bolted'to the manifold through holes '72. The base member is provided with fuel chamber 13 to which'tl'le fuel is introduced through bore 14' from coupling 15 connected'to fuel line 'l'by union 16; "The base member is provided-'with-bore' 11 and valve seat lflfleadingfrom chamber l'3 to nozzl'e lq provided with bore Wb'rl'd'ng'in"bore IT is needle "valve 8| provided withdongitudinal' recesses "82l The needle valve-'81 'iscontmlld-by a diaphragm 83 clamped between base: member H and cap 84. Cap 84 encloses biasing spring 85' which "presses needle valve? 8 lfion'toiit' seat;

The member" 7 I" isprovided with seat 8 6 adapted to be received-id a suitable" aperture: in V} intake manifold unit i in orderthat the fuel-may be injected into:the-manifoldwpassagew Under such conditions the-.needle valve-8l-is controlled by biasing-spring "85." and the-Jorceseexertedwn diaphragm; 83 by the fuel "pressure in-chamber. l3-andthe air pressure in-thespassage H10 which is conductedto=:-cl1arnber- 81- through bore 88 in base. rnember SH and -bore85 :of cap .mernber 84. g 1 V The .amount .01... airssuppl'iedsto .the. engine. is controlled by butterfly :throttle -valvesw9fll and M journaled in the passagesilfllllonshaft.92. Shaft '92 is mounted in unit5 on. bushings 93 194 and 95,as shown in Fig.9,

The butterfly Va1VBSI9O and'fil are operated through shaft 9? by' gear 95 on the end thereof. Gear 96 is rotated by rack 91 as shown in Fig'..10. Thefuel from line 1 is supplied by union98 and coupling 99through, bore 1'0! and port "12 to be selected.

work may be vented through bushing 95 to the manifold system or" if 'd'esi red' may be vented through an aperture in cap I01 to theouts'ide.

atmosphere; The" position taken by -th e butterfly valves and 9| is determined by the forces exerted by biasing spring I08, the pressure exerted supplied to the intake manifold from pump 8 can be controlled as desired by manipulation'of lever 69. In the absence of further adjustment of the operating lever the amount of fuel supplied to the engine per engine revolution is determined by the efliciency of the pump which will decrease somewhat with increasing speed. Except for this factor the fuel supplied per engine revolution is constant under these conditions.

When it is'desired to increase the engine output operating lever 69 maybe adjusted to increase the delivery of the pump to supply a heavier fuel charge. Therefore the amount of fuel supplied to the engine may be. delicately and accurately adjusted to the desired amount.

In order to obtain the correct air-fuel ratio the air intake butterfly valve is basically controlled in dependency on the amount of fuel being delivered to the engine by the fuel pump. This control is obtained through variations in the fuel line pressure caused by operation of th injector mechanism. As above described, the needle valve 8| is spring biased to closed position, and is raised off its seat by the pressure developed against diaphragm 83. Assuming an increasing delivery by the pump through operation of lever 59, fuel will be supplied to chamber 13 of the injector at an increasing rate, and the pressure therein will rise until the force is exerted in opposite directions on the needle valve by diaphragm 83 and spring .85 come into equilibrium, the increased rate of fuel supply being'accommodated by the further opening of the needle valve.

Through the mechanism of the injector, there I fore, the pressure in the fuelline is varied in accordance with the rate of delivery of the pump. This pressure is also delivered, a explained above, to the cylinder I03 where it acts on piston I04 to control the position of the throttle valve. The position taken by piston I04-through which the throttle valve is controlled is determined by the force exerted thereon by the fuel pressure and by the opposing biasing force exerted by spring I06. The size of piston I04 and the associated mechanism is suitably designed in accordance with the desired range of operating fuel pressures to actuate the throttle valve in cooperation with the biasing spring, as desired. Final adjustment after installation is attained by varying the compression on the biasing spring through cap I01.

Through the above described features of operation the amount of air supplied to th engine is controlled in accordance with the pressure of the fuel actually injected into the engine charge, and consequently it is possible to obtain the desired air fuel ratio over the necessary range of operating engine speeds. a

The charg forming system further compensates for variations in atmospheric pressure such as may be caused by variations in altitude or otherwise. Thus, a decrease in atmospheric pressure is directly communicated to chamber I08 on the upper side of the throttle-actuating piston I04. Consequently the decreasing atmos heric pressure permits the piston to rise further and therefore to open the throttle valve in: order to .permit' an increasedamount of. air to be supplied 7 again in equilibrium.

Whereas in the construction shown chamber I08 is vented to the atmosphere and also tothe passage I00 inside of the throttle valve, if desired it may be vented only to the atmosphere, or only to the passage inside the throttle valve.

In case a supercharger is employed chamber I08 may, if desired, be vented to the charge forming system between the superchargerand the throttle valve, this connection producing an equivalent effect to'that produced by venting chamber I08 to the atmosphere when a supercharger is not employed. 1

It will be understood that the relative effects produced on the throttle valve by the fuel pressure and airpressure in chamber I08 may be ,varied over a wider range through the employ- 'ment of differential pistons, or'if desired, by diaphragms of differing area operated on by the 1 fuel and air pressures.

In the embodiment shown the compensating efiect'is limited by the force produced on the outside of diaphragm 83 controlling needle valve 8| by the pressure admitted thereto through By this construction the air bores 88 and 89. pressure of the charge in passage I00 produces a further" effect on the position of the throttle valve by superimposing a variation on the fuel pressure in addition to that effected in dependency 0n the delivery of the pump.

The pressure communicated from the charge forming system through bores 88 and 89 to chamber 8'! acts directly a ainst the force exerted on diaphragm 83 by the fuel pressurefl Assuming a drop in the pressure of the chargein passage I00, chamber 81 is correspondingly evacuated and,. in dependency on the force thereby withdrawn from diaphragm 83, needle valve 8| is opened to lower the fuel pressure until the forces exerted on the needle valve by the diaphragm and spring'85 are The consequent reduction in fuel pressure in line I is communicated to piston I04 controlling the position of the throttle valve. This pressure reduction tends to permit the throttle valve to close under theoperation of biasing spring I06. It will therefore be understoodthat the compensation for atmospheric pressure variations produced by the action of piston I04 in dependency on the air pressure in chamber I08 is limited by the reverse effects of the fuel pressure variations in cylinder I03 resulting from variations in the pressure of the charge in passage I00. It will of course be understood that the pressure of the charge in passage I00, while responsive to other factors includin engine speed and throttle valve position, is also dependent upon atmospheric pressure. I Under certain circumstances particularly in aircraft engines which are most efficiently operated at fullIthrottle,,th'e opposing effects may preferably be substantially balanced so that, when the engine is so operating, variations in positions of operating lever: I59 serve to obtain a fine adjustment of the .air fuel ratio to obtain optimum engine efiiciency.

- It is clear that within the scopeof the invention therelative effects of pressure of the charge in passage I00 and air pressure in chamber I08 on piston I04 may be varied as desired byselecting the dimensions of piston I04 anddiaphragm'83, or by employing differential pistons or diaphragmsfor either of these elements.-

matic fuel valve and the air delivery pressure to control the position of the air throttle valve.

7. A charge forming system for an internal combustion engine comprising means defining a charge forming chamber, a manual control, a fuel nozzle discharging into such chamber, fuel pump means adapted to deliver fuel to the fuel nozzle at a variable rate independently of pump operating speed and fuel regulating means controlled by said manual control to vary the fuel delivery rate from the pump to the fuel nozzle, automatic pressure responsive fuel valve between the pump means and fuel nozzle for regulating the pressure of the fuel delivered by the pump to the nozzle and operative independently of the manual control in response to fuel delivery pressure and air delivery pressure, spring means biasing said fuel valve toward closed position in opposition to the fuel delivery pressure, an air throttle valve entirely automatic in operation controlling the delivery of air to the charge forming means at a variable rate, means responsive to fuel delivery pressure and air delivery pressure to control the position of the air throttle valve, and spring means biasing said air throttle valve toward closed position in opposition to the fuel delivery pressure.

8. A charge forming system for an internal combustion engine comprising means defining a charge forming chamber and an air intake delivering to the chamber, a manual control, a fuel nozzle discharging into said chamber, a. fuel pump means having a variable delivery controlled by said manual control to deliver fuel to said fuel nozzle at a varying rate independently of pump operating speed, an automatic throttle valve controlling delivery of air to the charge forming chamber at a variable rate, and means independent of the manual control and responsive to the pressure of fuel delivery to the fuel nozzle to control the position of the throttle valve.

9. A charge forming system for an internal combustion engine comprising means defining a charge forming chamber and anair intake delivering to the chamber, a manual control, a fuel nozzle discharging into said chamber, fuel pump mean having a variable delivery controlled by said manual control to deliver fuel to said fuel nozzle at a varying rate independently of pump operating speed, automatic pressure responsive fuel valve means between the pump and the nozzle for regulating the pressure of the fuel delivered by the pump to the nozzle and operative independently of the manual control in response to the fuel delivery, an automatic throttle valve controlling delivery of air to the charge forming chamber at a variable rate, and means independent of the manual control and responsive to the pressure of fuel delivery to the fuel nozzle to control the position of the throttle valve.

FRITZ STEPHAN.