US2400369A - Charge forming device - Google Patents

Description

Mai' 14; 1946. E. J. PARTINGTON I "2,4005369 CHARGE FORMING DEVICE 2 sheets-shea 1 Filed April 2, 1938 TN h u l 0 lb..

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INVENTOR. s 850m J. Pmrmrau ATTORNEY May 14, 1946.

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is sprayed into the induction passage i8.

l Vuninsured Mey 14, 194s' `MT1-:D STAT Es ,Pii'rlaziv'i ori-lcs l CHARGE FORMING DEVICE 4Edward J. Partington, vSouth Bend, Ind., assignor to Bendix Products Corporation, South Bend, Ind., a corporation of Indiana Application April 2, 1938, Serial No. 199,635'

16 Claims.`

This invention relates to charge forming dey vices, and more particularly' to carburetors or charge forming devices of the pressure feed type. An object of the invention is to simplify and improve devices of the type indicated. I

Further objects of the invention will'be'a'ppar-A ent from the following description, taken in connection with the appended drawings in which:

Figure 1 is a. diagrammatic sectional view of a A device embodying the invention;

Figure 2 is a fragmentary sectional view of a modified form of stern guide and seal,which may The fuel control mechanism of the device comprises an annular fuel chamber 44, a sleeve valve 48, and radial ports 48 in said valve so arranges' that axial movement of the valve regulates the available area for fuel flow therethrough. An

adjustable stop 49 limits the downward movement of the valve 48. Chamber 44 is supplied with fuel from a fuel pump 58 which may be of be substituted for the corresponding parts s hown in Figure 1;

Figure 3 is a diagrammatic sectional view of a modied form of the invention; and

Figure4 4 is a fragmentary sectional view of a any suitable commercial design, the one shown being of the radial vane type, having a fuel inlet 52 and a bypass passage 54 controlled by a pressure responsive relief valve 58 so as to supply fuel at substantially constantpressure to an outlet bpeassaige 68 which leads to the annular fuel cham- The mechanism for controlling lvalve member i48 comprises a casing 80 divided into chambers modified stem guide, which may be substituted in the embodiment shown in Figure 3.

In the embodiments illustrated in the drawings, the'arrangement isK that used with radial aircraft engines, though it will be apparent that the invention is not limited to such use.

Referring more vspecifically to the drawings, the device disclosed in Figure, 1 comprisesI a charge forming device including an induction passage i0, communicating -with a supercharger I2 of any suitable type, which in turn leads to an intake manifold i4 and thence `to the inlet port,` not shown.V of an internal combustion engine. The passage Ill is controlled by athrottle I8 which is operated by Arod I8 extending' from the pilots cockpit. Anterior to the throttle I6 is an air scoop 28 of .any suitable construction, which leads to a primary venturi 22, concentrically located in a-secondary venturi. 24 of any suitable contour. The primary venturi 22 is pro- 'vided with anannular chamber 28 opening .into

82, 84, 86, and 68 by relatively large flexible actuthe pressures on it may be compensated for by modifying the size of metering orifice 88. 'Seve eral ports 80 connect chamber 88 with/chamber 482 to prevent air, which might otherwise be the venturi in the vicinity of the Venturi throat,

so that said chamber and connected passages will be subjected to the depression existing at the Venturi throat. The secondary venturi is also provided with an annular chamber 28 which communicates with the air scoop 20 througha plurality of tubes 88, so that the pressure existing in the air scoop will be transmitted to chamber 28 and its connected passages, hereinafter described.

Posterior to the throttle is a fuel discharge noz- `zle 82', controlled by valve member 34, which is iixedto a flexible diaphragm 38 land urged to,- wards closed position by a compression spring 38. lA fuel passage 40 supplies fuel under pres-v sure to .the chamber 42 of the nozzle, whence it trapped in chamber 82, from acting as an air cushion which would interfere with the freedom of motion of the rod assembly.

The control rod 84 is secured to the actuating diaphragms I8 and I2 by plates 88 and 88, which are held in place by fixed sleeves or hubs 81 and e 88. 'I'he rod 84 is secured to sealing diaphragm 14 by hubs 81 and 88; the entire assembly being clamped securely by tightening a cap on the end of rod 84'. Cap 88 is provided with a ball end having a free sliding fit ina socket 8l formed misalignnient to be present between the control rod assembly and said sleeve valve without aff fecting the freedom of motion oi' said assembly.

Chambers 62 and 68 are interconnected by a fuel passage 92 which is provided with a calibrated orifice 93. Chamber 66 and its interconnected chamber 82 communicate by passage 94 with the annular chamber 28 in the venturi 24 and are therefore subjected to the pressure existing in the air scoop 20. Chamber 64 is conn nected by passage 95 with the annular chamber 26 in the primary venturi 22 and is therefore subjected to the depression existing at the throat of said primary venturi, which varies as a function of the rate of air flow through the induction passage I6.

When the engine is in operation, pump 50 supplies fuel at substantially constant pressure to the fuel chamber 44, whence it ilows through ports 48 -into the unmetered fuel chamber 68,

thence through passage 92 and restriction 93 to the metered fuel chamber 62, and thence through passage 40 to nozzle chamber 42, where it exerts and being discharged into the induction passage posterior to the throttle. Hence the pressure in chamber' 68 is greater than that in chamber 62 by the amount of the pressure drop acrossthe metering orice 93. The resultant of the forces scoop. The resultant force on the rod 84 of these pressures will therefore be in a direction to open the valve 46, since the differential in pressure between the Venturi throat and Venturi enpressure on diaphragm 36, opening the valve 34 trance varies as the square of the rate of flow of fluid through it, the resultant force exerted by the air pressures on rod 84 will be proportional to the square of the air flow. Since, for any given set of operating conditions, the rod 84 and attachedvalve 46 will move to such a position that the above two resultant forces will be in equilibrium, it is apparent that the rate of fuel flow will be adjusted by valve 46 to be directly proportional to the rate of air flow, thereby provid.. ing a constant mixture ratio throughoutv the range of air-flows utilized, unless varied by other means.

It is to be noted that in the instant invention four adjacent chambers are provided, the center two of which are subjected to pressures oi one fluid having a differential therebetween, and the end two are subjected to pressures of the other 'fluid having a diierential therebetween. The particular arrangement of the pressures relative to the chambers and the relative areas of the diaphragms should be such that the effective force resulting from the air differential pressure will tend to move the fuel valve in a direction to increase the fuel flow and the eiective force re.. sult'mg from the fuel differential pressure will be in the opposite direction tending to move the fuel valve in a direction to decreasethe fuel flow, it.l

being apparent that if both edective forces were in the same direction proper proportioning of v the air and fuel would not be obtained.

In Figure 1 the large Adiaphragms 10 and 12 have a primary function of actuating the control .rod and have been referred to herein as actuating diaphragms; whereas the small diaphragm has a primary function of sealing and has been referred to as a sealing diaphragm. It is pointed out, however, that the center diaphragml may be larger than theone shown, provided a difierential is maintained between the area of the middle and the outer diaphragms so that the differential in the pressures in the center two chambers will create a net force tending to actuate the fuel valve, it being apparent that if the three diaphragms of Figure 1 were the same size these pressures would have no effect on the fuel valve and fuel to air proportioning would not be obtained.

A modied form of the central section of the control unit is shown in Figure 2, and in many respects is similar to'the embodiment shown in Figure 1. For this reason, like parts are given like symbols with the addition of 100.

nFigure 2, has been so constructed that the part of said partition indicated at |18, is accurately machined to form a bearing for the hub |88, whereas that portion of said partition indicated at |19 is accurately machined to provide a fixed clearance around hub |88. By using ports |88 to bypass air around the bearing |18, the quantity of leakage becomes independent of the bearing t and is dependent only upon the amount of clearance provided at |19. Since whatever wear takes place will occur at the bearing |18 and not at |19, the area for leakage is of a fixed and known amount and can therefore be accurately compensated for as hereinbefore explained.

The modification shown in Figure 3 is generally similar to the embodiment shown in Figure l and vhence corresponding parts are given like symbols with the addition of 30G.

Fuel is received from the fuel pump, not shown, through the passage 358, whence it ows into the annular fuel chamber 344, throughvalve ports 346, into the unmetered fuel chamber 368, thence through passage 392 and lmetering orifice 393 into the metered fuel chamber 362, and thence through passage 340 to the discharge nozzle, not shown. Several ports 380 are located in the valve A346 to provide communication between chamber 382 and the unmetered fuel chamber 368, thereby chamber 28 in the secondary venturi 24 (Figure l) and is therefore subjected to the pressure existing in the air scoop.

As hereinbefore explained with reference to Figure 1, the differential in pressure between air scoop and primary venturi produces a net resultant force on control rod 384 and attached valve 346 which is proportional to the square of the rate of air ow and acts in an upward direction l, 1.In a charge forming devicel lcontrol rod assembly and valve 346 will adjust themselves to a position wherein the above two resultant forces will be in equilibrium, and hence the quantity vof fuel flowing will be maintained in constant proportion to the quantity of air flow unless altered by some extraneous force such, for example, the force exerted by idle spring 391 which is shown in Figure 3 as a compression spring surrounding a fixed stop 398 and having its upper end provided with a thimble 399 which is normally spaced from a nut 408 which is atpassage, a throttle therein, a venturi in the passage anterior to the throttle, a fuel conduit leading from a sourcevof fuel under pressure to the induction passage posterior to the throttle, a presf sure responsive valve controlling the conduit adl' jacentits outlet in the passage, a metering ori,

nce in the fuel conduit, a valve for controlling the ow of f-uel through said conduit, and con- I trol means for said valve comprising a casing, a

rigid partition in said casing, two actuating diaphragms in said casing on opposite sides of said partition, saidpartition and diaphragms dividing the casing into four chambers, a control rod passing through an aperture inA the partition and connected to the diaphragms and to the fuel con- `trol valve, pressure transmitting means connecting the two chambers separated -by the partition respectively to the venturi and to the induction passage anterior to the throttle and being so artached to the lower end of the control rod 384.

At valve port openings greater than for idle op.- eration, the rod 384 is entirely free of spring 391; however, when idle operationvis approached, the thimble 399 contacts the nut 400 and exerts thereon an upward force tending to keep valve ports l348 in open position. spring force is equalized by increased fuel flow, producing an enriched mixture for idle and nea idle operation.

A modified form ofthe central section of the control unit of Figure 3 is shown in Figure 4, in which the central sealing diaphragm has been eliminated. By making the valve 446 a very close,

This extraneous lapped, fit in the partition 416 the fuel leakage I from chamber 444 past the sleeve valve 446 into the chamber 464 can be reduced to a small amount. Since the pressure in fuel chamber 442 is maintained substantially constant by the fuel pump and the pressure in metered fuel chamber 464 is also'maintained substantially constant by the discharge nozale, the leakage past the valve will be a very nearly constant amount throughout the operating range. The quantity of leakage is a negligible percentage of the total fuel flowing at all conditions except at, or near, idle operation. At such conditions of operation the amount of leakage, though small, is a perceptible percentage of the total fuel flowing and hence will noticeably enrich the mixture. However, at idle operation an even greater enrichment than that resulting from leakage is required and is obtained by the use of anidle spring as herein-` before explained.

In the description of the several embodiments of the invention, the terms upward and fdownward have been used for convenience, but it will be understood that the control mechanism may be inverted relative to the carburetor, or the conacceleration, and is therefore especially suitable for inverted or acrobatlc flight. v D

Although the invention has been described with particular vreference to specific embodiments thereof, `it is not limited tosuch use, and may be embodied in other forms within the scope of the appended claims. A

I claim: l,

an 'induction ranged that an increase in the'ldiiferentialin the pressures in the said two chambers tends to result inmovement of the valve ina direction to increase the fuel flow to the inductionpassage,

and means communicating the .other two chambers respectively with the fuel conduit on opposite sides of the metering orice and being so arranged that an increase in the differential in the pressures in the said other two chambers tends to result in movement of the valve in av direction to decrease the fuel flow to the induction passage.

2.oIn a charge 'forming device for an internal combustion engine, an air passage, a throttle therein, a fuel conduit leading from a source of fuel under pressure to the air passage posterior tothe throttle, a pressure responsivevalve controlling the conduit adjacent its outlet in the passage, means in the air passage anterior to the throttle for creating a pair of pressures the difference between which varies in accordance with the rate of air flow therethrough, means in the fuel conduit for creating a pair of pressures the difference between which varies in accordance with the rate ofv fuel ow therethrough, anda control unit for controlling the flow -ofiuel to the air passage comprising/a casing, a partition in the casing, a pair of actuating diaphragms in said casingr on opposite sides` of said partition, said' diaphragms and the partition and the casing forming `four chambers, an aperture in the partition, control rod means passing through the aperture and connected to said diaphragms to be actuated thereby, a fluid control valve connected to the control rod means and in coaxial alignment with the control rod means and the diaphragms for varying the now of fuel through the fuel conduit, means for subjecting the chambers on opposite sides of the partition and adjacent thereto respectively to the pressures constituting one of said pairs, of pressures, and means for in addition a small sealing diaphragm connected to the partition and to the control rod means to prevent flow through said aperture.

4. In acharge forming devicel for an internal combustion engine, an air passage. a throttle in the passage for variably controlling the air supplied to the engine, a fuel pump, a fuel conduit connecting the pump'to the air passage, means in the air passage anterior to the throttle for establishing a pair of pressures the differential of which varies in accordance with variations in the air flow therethrough, means in the fuel condui`t-for establishing a pair of pressures the differential of which varies in accordance with variations in the fuel flow therethrough, and means for controlling the fuel flow to the air passage comprising a casing, la rigid partition separating the casing into two end compartments, diaphragms in the end compartments dividing the casing into four pressure chambers two of which are separated by said partition, means for subjecting the said two chambers respectively to the pressures constituting one of said pairs of pressures, means for subjecting the other two cham- 'bers respectively tothe pressures constituting the other of said pairs -of pressures, control rod means extending through the partition and connected to said diaphragms to be actuated thereby, and means including a valve connected to the control rod means for varying the ilow ci' fuel through the fuel conduit, said diaphragms, control rod means, and valve being coaxially aligned, and said subjecting means being so arranged that increases in the rst and second named differential of pressures respectively tend to move the valve in opposite directions.

5. In a charge forming device Ifor an internal combustion engine, an air passage, a manually operable throttle in thepassage for variably controlling the supply of air to the engine, a fuel nozzle discharging into the passage, a source of liquid fuel under pressure, a conduit connecting said source and the nozzleI metering elements in the air passage anterior to the throttle and in the fuelI conduit respectively creating air and fuel differential pressures variable in response to varincluding a. control unit casing, means including a pair of actuating diaphragms and an apertured partition therebetween dividing thev casing into four compartments, a control rod extending 'through the aperture and' connected to said diaphragms, a relatively small sealing diaphragm connected to the control rod and to the partition, a. valve for controlling the flow of fuel to the nozzle connected to said rod to be actuated thereby, said valvebeing in coaxial alignment with the control rod and with the diaphragms, means for subjecting the outer faces of said actuating diaphragms to one of said differential pressures bers, said members and diaphragm being operatively connected to the fuel control valve, and means for exposing the center two chambers to l one of said pairs lof pressures and the end two chambers to the other of said pairs of pressures, the differential in the pair of air pressures tending to move the fuel valve in a direction to increase the iuel ow to the engine and the differential in the pair of fuel pressures tending to move the valve in a direction to decrease the fuel of which varies in accordance with variations in the air now therethrough, means in the fuel conduit for creating a pair of fuel pressures the difference of which varies in accordance with variations in the` fuel flow therethrough,l and a conv trol unit comprising a casing, means including a pair of actuating diaphragms and a rigid partition therebetween for forming four pressure chambers in said casing, an aperture in the partition, a control member including a fuel valve iations in the air and fuel flow therethrough, and means forcontrolling the fuel flow to the nozzle tending to urge the valve in one4 direction and means for subjecting the inner faces of said actuating diaphragms to the other of said differential pressures tending to urge the valve in the opposite direction.

6. In a charge forming device for an internal combustion engine, an air conduit, a throttle in the conduit, a fuel conduitffor receiving fuel under pressure from a source and supplying it to fuel conduit, a casing, a pair of distortable pressure responsive members and a diaphragm therebetween in said casing dividing the casing into and forming parallel movable walls of four chamfor controlling the fuel flow through said conduit extending through the aperture and connected to said actuating diaphragms, means for subjecting the chambers adjacent the partition respectivelyto the said pair of air pressures, and means for subjecting the end chambers respectively to said pair of .fuel pressures, said diaphragms, partition and`subjecting means being so arranged that increases in the differential in' air pressures and in the differential in'fuel pressures Atend to result respectively in movement of the valve in directions to increase and decrease the fuel flow to the engine.

8. The invention. defined in claim 'I wherein the aperture comprises a bearing portion for the y control member, a second portion closely surrounding the control member but spaced therefrom to form a calibrated area for leakage, and a by-pass around the said bearing portion whereby the leakage between the said adjacent chamberswill be determined by the calibrated area.

9. In a charge forming device foran internal combustion engine, an air passage, a fuel conduit, a control unit comprising adjacent chambers subjected to vari-able air pressures developed in the operation of the engine, a rigid partition between said chambers, an aperture in the partition, diaphragms forming movable walls of each of said chambers, a movable control member extending through said aperture and connected to said movable walls to be actuated thereby, and a valve connected to the control member for varying the quantity of fuel flowing through said conduit, said aperture having a bearing portion for supporting the control member and a second 'portion closely surrounding said control member but spaced therefrom to form a calibrated area for leakage, and means for passing air past the bearing portion whereby the leakage between the adjacent chambers will be determined by the calibrated area. i

l0. In a charge forming device for an internal combustion engine, a control unit comprising a casing, a pair of actuating diaphragms and a rigid partition therebetween forming four adjacent chambers in said casingfan aperture in said partition, a movable control member extending through said aperture and connected to said actuating diaphragms. and a valve attached to said control member and cooperating with the aperture in said partition, a fuel conduit for supplying fuel to the engine including a portion within said partition controlled by saidpvalve, a metering restriction in the fuel conduit, means'communicating the center two chambers respectively with the conduit anterior and posterior to the restriction, anair passage for supplying air to the engine, means in said air passage for creating a pair of air pressures the differential of which varies in accordance with variations in the ilow through the air passage, and means communicating said air pressures respectively to the two end chambers.

11. The invention deiinedinclaim l comprisbeing in coaxial alignment means for transmitting one of said pairs of pressures to the chambers separated by the partition, and means for transmitting the other of said pairs of pressures to vthe other two chambers respectively, said transmitting means, chambers, diaphragms and control valve beingso arranged that `increase in' the differential of one of the pairs of pressures tends to increase the fuel flow to the air passage ing in addition a sealing diaphragm connected V to said partition and to the control member.

12. In a charge forming device for an internal combustion engine, a control 'unit having four adjacent chambers, actuating diaphragms separating the iii-st and second chambers and the third, and fourth chambers respectively, a partition separating the second and third chambers, an aperture in the partition, a fuel passage within the partition communicating with said aperture and transmitting fuel to be supplied to the engine, a movable control element extending through the aperture and connected to said diaphragms, a valve connected to said element and vcooperating with said partition to control the fuel flow through said passage, means for subjecting the second and third chambers to fuel pressures the differential of which varies in accordance with the fuel ilow to the engine, and

means forl subjecting the first and fourth cham.

bers to air pressures the differential of which varies in accordance with the air iiow to the engine. x

13. The invention defined in claiml2 comprising in addition a relatively small sealing diaphragm connected to the control element and to the partition to prevent leakage through said aperture between the second and third chambers.

14. In a charge forming device for an internal combustion engine, an air passage for supplying.

air to the cylinders of the engine, a throttle therein, means in the air passage anterior to the throttle for creating a pair of pressures the differential ofwhich varies in response to `variations in air flow therethrough, a liquid fuel conduit lead- I ing from a source of fuel under pressure to the air supply passage posterior to the throttle, a pressure responsivevalve controllingv the conduit adjacent its outlet in the passage, means in the fuel conduit for creating a pair of pressures the and increase in the differential'of the other pair of pressures tends to decrease the fuel flow to the. l

air passage.

15. In a'charge forming device for an internal combustion engine, an air passage for supplying air tothe cylinders of the engine, a throttle in said passage for variably controlling the air supply, means in the air passage anterior to the throttle for creating a pair o f air pressures the differential of which variesV in Vresponse tovariations in flow therethrough, a fuel conduitfor supplying fuel to the engine, a metering element inthe conduit for creating a pair of fuel pres# sures the Vdifferential of which varies in response to variations in flow therethrough, a control unit casing, a rigid partition in the casing, two actuating diaphragms in said casing on opposite sides of said partition, said partition andv diaphragms dividing the casing into four chambers, means for subjecting the chambers separated by the partition respectively to the said pair of .fuel pressures, means for subjecting the other chambers respectively to the said pair of air pressures,

`a central aperture in the partition in coaxial alignment with the diaphragms, and means for varying the fuel supply to the engine in accordance with variations in the air supply comprising a fluid passage in said partition communicating with said aperture, and a valve connected to said diaphragms and cooperating with said aperture to variably control said fluid passage.

16. In a carburetor of the type described. a hollow b ody member for attachment to an engine intake, a fuel-air mixing chamber inthe body member and an air conduit through the body member delivering to said chamber, a fuel conduit including a discharge orifice delivering to said chamber, means for supplying fuel to said fuelconduit under pressure, means fo'r establishing differential pressures in the air conduit and in the fuel conduit, a pair of distortable pressurelresponsive means in fixed relation to the body member coupled to each other in spacedrelation and each adapted to deflect under influence of fluid pressure, the nearest proximate sides of said means-being exposed to differential pressure in one of said conduits and the farthest remote sides of said means` being exposed to differential pressure in the other conduit, valve means in the fuel conduit in operative driven connection with said coupled means and arranged to be urged thereby toward .open position on increase in differential pressure in the air conduit and urged toward closed position by increase in dierential pressure in the fuel conduit, and throttle means in the body member adjacent said mixingl chamber.

' EDWARD J. PAR'I'INGTON.

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