US2216422A

US2216422A - Charge former

Info

Publication number: US2216422A
Authority: US
Inventors: Schimanek Emil
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-06-25
Filing date: 1937-06-18
Publication date: 1940-10-01
Anticipated expiration: 1957-10-01

Description

Oct; 1, 1940. E. scHIMANEK CHARGE FORMER 'Fi1ed,June 18, 1937 3 Sheets-Sheet 1 Oct. 1, 1940. E. SCHIMANEK CHARGE 'FORMER Filed June 18. 193'? 5 Shiaets-Shgei: 2

C? Sc z'wawa e pvmsnam Oct, 1, 1940.

E. SCHIMAN EK CHARGE FORMER Filed June 18, 1937 3 Sheets-Sheet I5 .rrlllv d 'AiMEVHIr/( Patented Oct. 1, 1940 Application June 18, 1937, Serial No. 149,037 In Austria June 25, 1936 2 Claims. (01. 261-69) This invention relates to internal combustion engines working with a mixture of fuel and air,

-' wherein the fuel is injected under pressure into' the current of air flowing to the engine cylinder,

8' and wherein the carburettor is replaced by a fuel injection device.

The known methods of injecting fuel into the suction air have the disadvantage that the quantities of fuel injected are not adapted to 10 the various operative conditions. It is found by experience that the compositions of the mixture in the case of mixture motors (explosion motors), in which the carburettor is replaced by an injection device is very variable, so that the composition of the mixture, when correctly adjusted for a certain load and speed of revolu tion, undergoes at other loads and other speeds such an alteration that the power output of the engine diminishes, whereas the fuel consump-' tion is increased. It even happens in certain circumstances that at the altered load the mixture is no longer explosive. These disadvantages particularly apply in the case of those engines which work with air of very variable specific 5 gravity, for instance aircraft engines. At a height of about 6000 metres aircraft engines work with air of half the specific gravity of the air in the neighbourhood of the earths surface. It is.in these engines that the need-arises for sucked in by an artificially increased vacuum the suction air, that is to say, devices delivering at a raised pressure. Not only in aircraft engines without compressors but also in aircraft engines with compressors the replacing of the carburettor by a device which injects the fuel into the induction pipe or into the air pathleading to the engine cylinder under a raised pressure presents substantial advantages, including prevention of theformation of snow and ice on the throttle valve. i

This invention relates to means for regulating the delivery of fuel under a raised pressure into the path of the air to the cylinder of a mixture engine,'and the invention consists in the feature that between the device that delivers. the fuel under pressure and the path of the air to the engine (induction pipe of the engine, injection nozzle or the like) one or more pressure regulators-are interposed, which vary the injection pressure and therefore the quantity of fuel injected, according to the weight of the air that is being dealt with at any particular time.

replacing the carburettor, in which the fuel is by way of example in the accompanying drawings, in which Figure 1 shows an example in which the sup: ply of fuel is regulated by means of a difference of pressure occurring in the air path to the ,engine, this pressure difference acting .upon the differential diaphragms;

Figure 2 shows an example in which'surfaces of the same area are presented to the pressures obtained from different points .on the air path,

and 1 2, is constricted at 4, and then widens out again so that the connection 3 to the engine is of the full cross-sectional area of the induction pipe.

Owing to the constriction in the cross-sectional area of the'pipe adifierence of pressures of the flowing air available for regulating purposes is obtained on the principle of the Venturi. tube,

' the pressures utilized for regulating being preferably obtained at 6, the narrowest point, and at a point of maximum cross section, as at 1, these two points furnishing the maximum difference' of pressure. Owing to the throttling, which may however be obtained in some other way, if preferred, for instance by means of a throttle disc or the like, a difference of pressure in the flowing air is produced, which varies with the weight of air flowing through. The device is preferably such that'the cross-sectional area of the tube at the widest part is greater than the opening or diameter of the suction pipe.

In the suction pipe I is provided a throttle valve 5 regulating the power output of the en.- gine, either before or after'the Venturi tube ,4 or the connections 1 and 6 of the regulating appliance.

The pressure difference "occurring in the induction pipe'is utilized by two diaphragms of different sizes, namely a small diaphragm II and a large diaphragm 12, which are united by a connecting piece l3 to form a differential diaphragmior the purpose of regulating the supply transmitted, by a tube 6, the pressure prevailing in the suction pipe at the connection point 6,

while in the chamber 8 the pressure transmitted pressure prevailing in the chamber I0.

by a tube 1' from the connection point I prevails. To the chamber Ill fuel under pressure flows through a pipe I5 and a. valve I4, which is controlled by the differential diaphragm and regulates the fuel injection pressure in the chamber III.

The pressure under which the fuel is supplied through the pipe I5 to the regulating member,

for instance by a fuel pump or the like, must be higher than the maximum injection pressure required, which prevails in the chamber Ill. The pump delivery pressure is preferably kept constant by regulating it to any convenient height, by means for example of an over-flow valve with adjustable loading.

In the regulating device the pressure prevailing in the chamber 9, the smaller of the two pressures employed for regulating, namely the one obtained at the point 6 of greater air speed, acts upon the adjacent surfaces of the larger and smaller diaphragms, while the greater pressure, prevailing in the chamber 8, only acts upon the larger diaphragm. There is therefore exerted, by the pressures prevailing in the chambers 8 and '9, upon the differential diaphragm, an upward force which counterbalances the fuel injection Owing to the differential action of the diaphragms of different sizes, the result is here obtained that the fuel pressure adjusted in the chamber I0 is greater than the greater of the two pressures employed for regulating, namely, the pressure prevailing in the chamber 8; this pressure prevailing in the chamber 8 may however be atmospheric pressure.

In order to make the fuel pressure act upon the diaphragm I I independently as far as possible of the position of the regulating means, which is particularly important in the case of aircraft engines, which must be capable of working even in an inverted position, the chamber I0 is kept so low, or the distance of the nozzle 2I from the diaphragm I l is kept so small, that the weight of the column of fuel loading the diaphragm II may be neglected in practice.

Under the pressure prevailing in the chamber I0, fuel is forced out of the nozzle 2 I, through the pipe I9, to the place 23 in the induction pipe I, the introduction of the fuel into the air path being effected at any convenient point, before or after the throttle valve, or, in the case of compressor engines, before or after the compressor.

In the example illustrated in Figure 1, the fuel forced through the nozzle, mixed with a certain quantity of air, flows as froth or preparatory mixture into the suction pipe. The air necessary for the formation of froth is obtained from the suction pipe and led by a tube 20 to the mixing point 22, where the air ismixed with the fuel forced out of the fuel nozzle 2 I, and the preliminary mlxture, or foam, flows to the suction pipe through the tube I9. In this case the tube .20 is connected to the suction pipe at a point at which a pressure prevails which is equal to one of the two pressures employed for regulating.

The apparatus according to Figure 1 operates in the following manner:v When the motor is at rest the same pressure prevails in all three of the chambers 8, 9 and I0. Consequently the valve I4 remains closed, and the admission of fuel to the chamber I0 is shut off. This closure may also be assisted by a weak spring closing the valve I4,

When the engine is rotated a diiference of attained a certain magnitude; that is, the pres-" sure with which the fuel is forced through the nozzle 2|. When this pressure is reached, it remains unaltered so long as the engine is working with the same weight of air, for if the pressure in the chamber II] increases, the valve I4 closes; or if the pressure decreases the valve I4 opens.

The fuel is therefore forced through the nozzle v 2| by a raised pressure, and passes thence, either unmixed or mixed with air to form a froth, into the suction pipe.

To a larger or smaller weight of air dealt with in the engine there corresponds a greater or smaller difference of pressure in the path of the air to the engine, and therefore a greater or smaller difference of pressure in 'the chambers 8 and 9. The fuel pressure in the chamber I 0 is thereby regulated to a higher or lower value, the quantity of fuel expelled through the nozzle 2| being increased, in dependence upon the fuel pressure, to correspond to the greater weight of air, or diminished to correspond to the smaller weight of air.

The arrangement according to the invention is such that for one cylinder, or in place of one carburettor, either one or more such regulating appliances are provided, the fuel being supplied to the regulating appliances by a single fuel pump or to each regulating appliance by a separate pump. Thus for example in multi-carburettor engines, one carburettor in each instance may be replaced by a regulating, appliance according to the invention.

In the embodiment illustrated in Figure 2, the suction tube I of the engine, into which air flows in the direction of the arrow 2, is constricted at 4 and then widens out again so that the full crosssectional area is restored at the point 3, to which the engine is connected. The pressure difference, which effects the regulation, in the air flowing through the suction pipe, is also obtained or increased artificially here by constricting the cross section of the pipe in the manner of a Venturi tube, the pressures employed for regulating preferably being taken from the narrowest point at 6 and from a pointof maximum cross section such as I, that is to say, at points between which the difference of pressure is greatest. .It is preferable that the cross-sectional area of the tube at the widest point should be greater than the cross-sectional area of the suction pipe. Owing to the throttling, which may alternatively be obtained in some other way, for instance by means of a throttle disc or the like, a difference of pressure is therefore produced in the flowing air,

' These two diaphragms are arranged ina casing,

which is divided by the diaphragms into three

parts

38, 39 and 42. To the chamber 42 the fuel 'pipe is connected by way of the valve I4, through .which the fuel delivered by the fuel pump enters the chamber 42.

The

chambers

38 and 39 are subject to the pressures obtained from the suction pipe at two different positions, namely the outer chamber 38 through the medium of the pipe 8a to the smaller of the two pressures, and the chamber 39 between the two diaphragms through the medium of the pipe in to the greater of the two pressures, so that the fuel pressure in the chamber 42 is determined by the gaseous pres sures prevailing in the

chambers

38 and 39.

The two diaphragms are connected with one another by a sort of toggle mechanism, consisting of rods 25, which are attached to the dia-. phragms by pivotal joints 3.l and 32and are pivotally connected-with one another on guiding

levers

33 and 34 at 24 and 26, so as to form a jointed quadrilateral, two corners of which are attached to the diaphragms and the other'two corners, to theguiding levers. The guiding levers are rotatable about pivotal points 21 and 35, and effect the guidance of the

pivotal points

24 and 26 in a direction normal to the direction of movement of the pivotal points 32 or of the

diaphragms

40 and 4|. For the purpose of balancing the weight the guiding levers 33 and 34 may be connected with one another by a rod 29, whichis connected to the-guiding

levers

33 and 34 at the

points

28 and 30 respectively.

Under the pressure prevailing in the chamber 42 the'fuel is forced out of the nozzle 2 I, through the pipe I9, and into the induction pipe I at 23, in which case, in the constructional example illustrated in the drawings, the fuel passes into the pipe I9 already mixed with air supplied by the pipe 20.

If two diaphragms of equal size are employedthere acts upon the lower diaphragm 4| from above the greater pressure 111, and from below,

- the smaller pressure 122, thus producing a downward force equal to the pressure difference p1 minus m. This force is converted, by the mechanism formed by the four rods 25, into an upwardly directed force, and thus transmitted to the upper diaphragm 40, upon which there acts, in addition to this force, the pressure differences in the

chambers

39 and 42, amounting to 11;; minus 171. In a state of equilibrium, the pressure difference n minus pi must counterbalance the force p minus 112.

If the two diaphragms are made equal in size, and the greater pressure 101 prevails in the chamber 39 and the smaller presure p: in the chamber 38, the fuel pressure 123 in the chamber 42 will be equal to in plus 111 minus 112. The same effect is therefore obtained as if a differential diaphragm were employed, of which one surface is twice as great as the other, and the pressure n acts on the external surface of the larger dia-.

phragm, whereas the force 1): acts between the two diaphragms.

In the embodiment illustrated in Figure 3, besides a pressure regulator A, hereinafter referred to as the main pressure regulator, which is similar to that of Figure 1, a second pressure regulator B is provided, which serves for idle running. The main pressure regulator A'includes two diaphragms or thelike 46 and 41, which are connected with one another and which control the fuel valve 43. The fuel regulator is divided by the diaphragms 46 and 41 into three chambers '60, BI and 62. The fuel flows to the pressure regulator through a tube ,63 and passes into the chamber 62, from which, after being mixed with air, if desired, supplied: by a tube 66 connected to the chamber 60, it passes through a point 4.

to the pressure supplied through

tubes

68 and 69;

'lating the supply of fuel.

main nozzle 34 and a tube 65 and is supplied to the suction tube I, which it enters at the point 61. The chamber BI is subject to the pressure that prevails. in the suction tube at the narrowest The chamber 60, however, is subject which are connected to the suction pipe at a position of full width.

The second pressure regulator B is similarly equipped with two diaphragms 48 and 49, which are connected with one another and-control the fuel valve 44. These diaphragms divide this pressure regulator into three chambers I0, H and 12. The fuel here passes through-a tube 13 into a chamber I4 and from there, controlled by the fuel valve 44, into the chamber H, from which it is delivered by way of a nozzle 15, and a tube 16 into the suction pipe I, which it enters at the obtained at the margin of the throttle valve 5,

by means of a pipe 35 which is connected at the point 18 in the suction pipe, where the throttle valve, in its closed position,-establishes a rather marked vacuum, and the chamber 12 is connected by the tube 68 and a branch pipe with as wide a part as possible of the suction pipe. The tube 16 leading the fuel into the suction pipe opens into the suction pipe at a point beyond the position where the throttle valve 5 is arranged therein.

These two pressure regulators operate in following manner: The fuel is delivered jointly by the two pressure regulators A and B. At relatively large loads, at which the throttle valve 5 is open, the fuel supply is effected for the most part by the main pressure regulator A, through the nozzle 64. At relatively low loads, and when there is no load on the engine, the quantity of fuel flowing in through this nozzle is small, owing to the small difference of pressure which occasions the fuel pressure in the fuel pressure regulator, and themain quantity of the-fuel required passes into the suction pipe through the nozzle I5, and is regulated by the second pressure regulator B. It is of course also possible to employ more pressure regulators, which deliver the fuel into the suction pipe in dependence upon two other suitably selected pressures each.

In certain cases, in aircraft engines for ex-v ample, it is not suflicient to make the delivery pressureof the fuel dependent upon only two pressures in the suction pipe. It is necessary to utilize a third pressure as well, which mayjor instance advantageously be dependent upon the existing pressure of the atmosphere, or may be the pressure of the atmosphere itself, for regu- According to'a further feature of the invention such a pressure regulator may be constructed in which the fuel pressure is regulated in dependence upon three different pressures. Such an arrangement presents advantages in numerous cases. The uti-,-

lization of the atmospheric pressure for regu1atlating purposes three different pressures in the.

suction pipe.

Figure 4 'illgistrates by way of example an emfor the fuel entering from a tube 88, this fuel flowing, in a quantity regulated by a valve 90, through a jet 9| and a tube 92 to the point 93, where it enters the suction pipe. The fuel may be mixed beyond the jet 9| with air obtained from the chamber 86 of the pressure regulator, through a tube 94.

The chamber 81 is connected with the narrowest part of thesuction tube at 4 by a tube 91. The chamber 86 is connected with a wide part of the suction pipe by a tube 88, and the chamber 85 is connected by a tube with a wide part of the suction pipe or with the atmosphere, the connection of one of these two chambers to the suction pipe being established before the throttle valve and the connection of the other beyond the throttle valve.

The action of this device is thesame as if there were only two diaphragms. The difference resides merely in the fact that three different pressures influence or control the fuel pressure in the chamber 88. The fact that among these pressures the pressure of the atmosphere has some action is of special consequence in aircraft engines.

The embodiment illustrated in Figure 3 can of course also be so constructed that one of the two pressure regulators is made in accordance with Figure 4.

What I claim is:

1. In charge forming apparatus for internal combustion engines, an air induction pipe having a constricted portion providing a Venturi tube, -a throttle valve in said pipe anterior to said Venturi tube, means for supplying fuel under variable pressure to said air induction pipe comprising a sealed casing having fixed end walls, dia-- 'pipe including a calibrated metering restriction,

a conduit leading from a source of fuel under substantially constant pressure having a discharge orifice in said fuel chamber, a valve regulating the fuel flow through said orifice, rigid means connecting the central portion of said diaphragms and said valve, fluid pressure transmit ting conduitsextending between the Venturi tube and a second of said chambers and between the unrestricted pipe and a third of said chambers whereby the larger diaphragm is subjected to a differential pressure varying with the air flow in said pipe while the smaller diaphragm is sub- 2. In charge forming device for internal combustion engines, an air induction pipe having a I! constricted portion providing a Venturi tube, a throttle valve in the pipe beyond the Venturi tube, means for supplying fuel under variable pressure to said air induction pipe including a sealed casing having fixed walls, yieldable diaphragms of unequal areasseparating said casing-into chambers one of which provides a fuel chamber bounded by the smaller diaphragm and one end wall of the casing, a tube for introducing fuel under pressure into I said fuel chamber, means for discharging fuel from said fuel chamber into an unconstricted portion of said pipe including a calibrated metering restriction, a fuel valve regulating the fuel flowing from said tube into said fuel chamber, rigid means connecting the central portion of said diaphragms and said valve, a pipe extending from the constricted portion of the air induction pipe to a second of said chambers, a conduit extending from the unrestricted portion of the air induction pipe to a vthird of said chambers whereby the larger diaphragm is subjected to a differential pressure varying with the air flowing in said pipe while the smaller diaphragm is subjected to the Venturi pressure and the fuel pressure, and movement of the smaller diaphragm against the fuel increasing the valve opening and permitting the production of increased fuel pressure in said fuel chamber.

EMIL SCI-HMANEK. 5