US2754186A - Controlled gaseous fuel feed system for internal combustion engines - Google Patents

Description

July 10, 1956 R. F. l-:NslGN 2,754,185

CONTEOLLED GAsEous FUEL FEED SYSTEM EOE INTERNAL COMBUSTION ENGINES Filed Deo. 9, 1952 rro/eA/Eys.

CONTRGLLED GASEGUS FUEL FEED SYSTEM FOR BITERNAL COMBUSTION ENGINES Roy F. Ensign, San Marino, Calif., assignor to Ensign Carburetor Company, Huntington Park, Calif., a corporation of California Application December 9, 1952, Serial No. 324,985

6 Claims. (Cl. iS-184) In a typical gaseous fuel feed system for internal cornbustion engines, a pressure regulator takes fuel at high pressure from a pressure fuel source and delivers the fuel to the Venturi throat of the engine carbureter at a slightly sub-atmospheric pressure-typically about minus one-quarter inch of water. The constant reference pressure on the diaphragm-valve system of the regulator, the pressure that tends to open the valve, is a minus pressure. The valve is thus closed by that minus reference pressure When the system is standing; and in operation the regulator, subject to certain pressure modifications specifically for idling, etc., then delivers fuel more or less constantly at the sub-atmospheric pressure for which it is set. See, for instance Ensign Patents 2,073,299 and 2,248,222.

One of the short-comings of such a system is that, on turning over the engine to start, the venturi throat depression, with the throttle in closed position for idling, is not sutlicient to draw in fuel at the set sub-atmospheric pressure. Hence for starting either the throttle has to be opened, or a choke applied to the carbureter air intake, to lower the pressure at the venturi throat to or below the sub-atmospheric denvery pressure of the regulator. After starting, the regulator continues to deliver at the set sub-atmospheric pressure, subject to specific modifications such as mentioned.

Ideally, in order to maintain fundamentally a lixed fuel-to-air ratio throughout all ranges of engine operation, the regulator in operation should deliver at atmospheric pressure; or, more specifically, at the atmospheric pressure existent at the carbureter air intake.

The general object of the present invention, in a system where the regulator at rest has its valve closed by the reference pressure (typicalry a valve closing spring), is to provide for the balancing of the forces acting on the diaphragm-valve system at a delivery pressure substantially equal to the effective atmospheric pressure, during starting turnover and substantially throughout all ranges of engine operation.

Briefly, the invention accomplishes that objective by taking oif from the engine manifold a substantially fixed depression which is substantially not more than that occurring on turn-over for starting; preferably substantially not more than the minimum depression occurring on starting turn-over. That fixed amount of depression Vis then, during starting turn-over and throughout the en` gine operating ranges, applied to a depression-actuated means which operates to apply to the diaphragm-valve system a valve-opening reference force substantially equal to the valve-closing reference force.

That depression-actuated means may take various forms. The one here shown, and preferred, is the delivery sub-chamber arrangement shown in the two Ensign patents referred to, particularly the latter. The invention will thus describe herein an illustrative ernbodirnent utilizing such a sub-chamber. And it will also be described typically with reference to a standing valve closing pressure equal to one-quarter inch of water on the effective diaphragm area. But it will be readily 2,754,186 Patented July 10, 1956 understood from what follows that the standing valve closing force may be as large as can be in practice balanced by the depression actuated means actuated by the substantially lixed depression taken from the manifold.

Fig. l and Fig. 2 are schematic sections showing typical embodiments of the invention.

Fig. l shows the elements of a typical tiuid pressure regulator; pressure regulating valve lil controlling au inlet 11 and operated by diaphragm 12 which has one face exposed, mediately to the pressure in the delivery chamber 13 into which the fluid liows under control of valve 10. Valve 10 is illustratively shown as carried by pivoted valve lever 14, as closing against the pressure in inlet 11, as being normally closed by a spring 1S and opened by movement of diaphragm 12 into or toward chamber 13. That chamber is shown as divided into two parts 13 and 13a by a division wall 16. The subchamber 13a directly adjacent the diaphragm is connected to delivery chamber proper 13 by a restricted passage or passages; such for instance as the aperture 18 through which the valve lever 14 passes loosely. Although in general the uid pressure in 13a will follow and be substantially the same as in 13, that in 13a can be modified to cause action of diaphragm 12 different from that which would be caused by exposure of the diaphragm directly to the pressure in 13.

As here shown typically and illustratively, delivery chamber 13 discharges through outlet 20 to the fuel nozzle 22 in the throat of a venturi 24 of a typical carbureter which has an air intake at 25, a throttle 28, and outlet connection with the intake manifold 35i of an internal combustion engine. The air intake may be equipped with an air cleaner or other device, and a pitot tube 32 picks up the total intake pressure for a balance tube 34 which applies that pressure as a reference pressure to the reference chamber 36 at the back side of diaphragm 12.

In such a gas feed regulator system spring 1S will typically be chosen or adjusted to hold valve 10 closed with a force equal to, say, a pressure of one-quarter inch of water on the eective area of diaphragm 12; so that, to balance the diaphragm-valve system, the pressure on the inner face of the diaphragm-the face in chamber 13 or 13a-must be that much less than the pressure in reference chamber 36 on the outer face. On slow turnover of the engine for starting, and at idling with the throttle closed down, the pressure drop at the venturi throat is not ordinarily suticient to produce enough pressure difference on the diaphragm either to open the valve at all or t0 open it wide enough to deliver suiiicient fuel. In past systems various arrangements have been used or proposed -to overcome that dculty, including chokes in the air inlet and fuel by-passes to the intake manifold beyond the throttle. The Ensign patents referred to describe a system wherein, by utilizing the isolating wall 16, the actuating pressure on diaphragm 12 may be modified by pressures introduced from the intake manifold; and the present invention in this typical form utilizes that system of modification.

As shown in Fig. l, a second diaphragm 40 is mounted between two diaphragm chambers 42 and 44 in the same casing structure that holds diaphragm 12. Chamber 42 is in open communication with reference chamber 36; in fact the two chambers here form in effect a common reference chamber between the two diaphragms subjecting both to the intake air pressure as a reference. The other face (upper as shown here) of diaphragm 40 in chamber 44 is here exposed to a pressure derived from the pressure in the intake manifold 36. A connection passage 46 leads from the intake manifold, at a point which is always down-stream of throttle 28, to and through a downwardly facing valve seat 48 mounted in the upper Wall of chamber 44 directly above a at valve pad""car`ri`ed on ythe c'enter'of the plate 41 of diaphragm 4t?. A spring 5-2, with pressure-adjustable at'54, pressesY down on the diaphragm plate to press valve pad 50 away from seat 48. The pressure of that spring determines the'amount by which pressure in 44 (subject to'a modiii'cation statedlater) must be lower than 'the reference pressure in 42 to move the diaphragm up and'close the valve at 48, 5). For purposes of descriptionthe spring pressure may be taken to be the equivalent say of about six inches of water on the effective area 'of the diaphragm. With the engine turning over, the pressure in 44 will then be, in general, the pressure obtaining'in the intake manifold up to a maximum of minus six water'inches with reference to the pressure atl the air intake.

From chamberv 44 a passage 60, controlled by manual valve 62 leads-to the-delivery sub-chamber 13a. Adjustment of themodiiicationy of the pressure inr13a caused by the/application to that chamber of the lower pressure obtaining in 44 may be made Yeither by adjusting spring 52 to'adjustably change the regulated vacuum in 44, "or' by adjusting the size of the valve orifice. at 62,or by bothv adjustments.

Spring 52 is-set to hold diaphragm '40, and-its'valve padSt), down'against a diierential pressure on itsfaces which. is equal to approximately themanifold depression which occurs on starting turnover with the throttle closed downto itsidlingv position. That depression varies 'with various factors, particularly with the speed of turnover; and-'preferably the pressure for which spring 52 isset is not more than, and again preferably about equal'to, the minimum starting turnover depression. Typically that minimum can be taken to be a depression equal to about six inches of water. With spring 52 so set, the depression in'- 44 will be approximately the same during all-startingV operations. During the slower turnoversthe valve at 48,50 may remain wide open with the depression in 44-sligh`tly less than six inches. That relative depression, transmitted lunder control of62 to 13a will lower thev pressure in 13a by an amount which may be Vtaken to be approximately equal to or slightly greater than the p. s. i. equivalent, say vone-quarter Vinch water, by which valve is normally held closed. The result is that valve 10fis thus positively opened or the valve operating system-is put in equilibrium so that the very slight' pressure drop'in the venturithroat will open it; preferably the former so that the mixture will be rich enough for starting. In other words, lowering the pressure in'diaphragrn chamber'la increases the opening force on valve 1'0 'so that the valve-will open to maintain a higher pressure 'in the outlet chamber 13 than would be the 'case Vif the pressure -ink13 acted directly on the diaphragm. The dif'erence'between the pressures in 13 and 13a is set by two factors, (-a) the lamount of depression applied' to 13a,

and l(b) the size ofthe restricted leak between'the two chambers. Valve 62 is 'adjusted for the best idle mixtureand remains the same during starting. 'The' suctionY in-f44l-being regulated and nearly constant will'draw a. constant-amount of gas through 62even though 'the opening of valve Stlwill vary widely. This amount however becomes an increasingpercentage of the total fuel as the-total Afuel requirement decreases, as at' starting.

On starting into operation at any ordinary powerA range orspeed or at idling with'closed throttle, the intake manifold depression becomes much greater than `during starting turnover. Infact, at any power range andQspe'ed with the-possiblefexception onlyof slow speed operation with throttle wide open (lugging) the manifold depression isalwaysV greater than 'during starting. Consequently, ongoing into operation at any usualpower range or-at' idling, the manifold depression increases to more, and at idling much more, than the six' inches'for which spring 52 is set.v Diaphragm 44)' is thus'drawn upto close vvalve 50 on seat 48 and then to controllinigly operate valve 50 so as to maintain in chamber 44L`a pressure which is determined by all ftheforcesoperating onvcliaphragm 40. And it is to be observed vthat once diaphragm 40 and its valve 50 are moved up close to'seat 48, then the manifold depression acting directly on valve 50 is added to the forces tending to close the valve. The result is that the depression which is maintained in 44, particularly during idling whenthe manifold depression is high, is less than during starting. How much less depends'jonth'e relative area of the valve at 48, S0 and on the spring rate of spring 52. It has been found that, as between starting and idling, the depression in 44 should not change-by morethan about one inch of water. That limitation can be had by making port48 suitably small, say about one-eighth inch diameter to three inches effective diaphragm diameter, and suitably choosing the spring rate. Under those conditions, if valve 62 is then set to obtain the proper idling mixture, the mixture for starting will, although richer, not be too rich.

Fig. 2 shows certain modifications. Parts corresponding to those shown and explained inv Fig. l are given the.v

same numerals and have the same functions. That is ltrue carburetor, the pressure controlling valve, itsV operating diaphragm and the diaphragm chambers. As in Fig. l, reference chamber 36 of valve operating diaphragm 1'2 is supplied with the air intake pressure as a reference pressure.

In Fig. 2, the reference pressure for the auxiliary diaphragm 40a, instead of being air intake pressure is the regulated outlet pressure present in outlet chamber 13. With Vthat in view and for simplicity of design and structure the auxiliary diaphragmrin lfigLZ is placed contiguoust'o chamber 13 rather than to chamber 36 as in Fig. l. Thus, in Fig. 2, diaphragm 40a is shown below chamber v1'3 with its upper face exposed tovpressure in that chamber. Chamber 44a which corresponds to chamber 44 of Fig. 1 is formed under diaphragm 40a.in a casing part 44b and is-connected to chamber 13a by passage 60a controlled by valve 62a. Spring 52a corresponds in function to spring S2. It is not shown to be adjustable, but'ma'yha've adjustment, or be in effectadjustable by ch'oic'e'and substitution of different springs to set the pressure with which the spring presses thediaphragm upwardly into its reference chamber 13.

4The apertured valve seat 48a, here located below diaphragmplat'e 41a, corresponds to aperturedvalve seat 48 of Fig. l; and connection 46a'similarly connects it to intake manifold 30. Diaphragm, plate 41a may here perform the valving action on seat 48a; or a valve pad' like 50 of Fig.v l may beprovided. In practice it has'been found`that Vthe metallic diaphragm plate itself will'seat with sufcient sealing eect on such a seat' as 48A or 48a,

ifthe" diaphragm plate is made to seat flatly. 1n Fig. 2l

this'is insured'by seating lugs 48b locatedopposite the seat 48a. In'Figpl' similar seating lugs 48o are located at'a side of valve seat 4S opposite to spring 52.; the spring forming in effect another seating lug when the-diaphragm moves up to seat=50on-48.

At the 'low airv speeds through the venturi which accompany starting turnover and idling operation, the pres- 'f ation involving larger air flow through the carburetor andV lowerpressure in the venturi'throat and in delivery chambe'r V'13, V'thepre'ssure'in chamber 44a will'automatically become Lslightly lower. The modilication effect on the pressure in' 13a will correspondingly become greater, to

somewhat lower that pressure, to open valve 10` and thus. trgsupply more'ffuel and tend to raisethe pressure ,in V1?l An additional functional f als'the' demand for fuel at 22 increases. And that action is particularly notable on sudden acceleration by opening the throttle. The pressure at 22 and in 13 suddenly drops and tends to open the valve at 48a, momentarily dropping the pressure in 44a to a point below its sub-six inch normal and thus momentarily abnormally dropping the pressure in 13a and opening valve 10 for momentary delivery of more than normal fuel.

The relative arrangement of the diaphragms shown in Fig. 2 has a further advantage over that of Fig. l. In practical use, the devices are usually mounted with their diaphragms in vertical planes and the valve levers swinging in horizontal planes; so that the weights of those parts do not aect operations. However in an automobile the devices may be tipped considerably; and when the inclination is such as to cause the weight of main diaphragm 12 and lever 14 to tend to close valve 10, the mixture will be thinned; when inclined oppositely the mixture will be enriched. By placing the auxiliary diaphragm so that its weight tendency is opposite to that of the main diaphragm, compensation is effected. That is so, in the valve and diaphragm arrangement shown when the valve seat of and seat 4S both face in the same direction, as in Fig. 2. In Fig. 2, if the weight of diaphragm 12 and connected parts tends to open valve 10, then the weight of diaphragm 40a tends to close 48a, reduce the depression in 44a and thus to increase the pressure in 13a and tend to close valve 1G. In general, compensation takes place if the arrangement is such that the gravitational tendency of the two valve actuating systems tends to open one valve and close the other.

Another control function to which the limitation of intake manifold suction lends itself with improved results is that of the well known idle by-pass. In previous systems an idle by-pass leading from the regulator delivery, at a point on the regulator side of the fuel orifice 22, to the intake manifold down-stream of the throttle, has been commonly used, under control of an adjustable orifice. A pressure lowering suction from the manifold is thus placed on the regulator delivery, causing the regulator to deliver more than normal fuel to be drawn via the by-pass directly into the manifold at cranking speed. If such a by-pass has its suction end acted on by the limited manifold vacuum, it will act to supply starting and idling fuel with the throttle closed and, like the systems previously described, without the use of a choke.

In the designs of both figures it is only necessary, to create such a controlled by-pass, to provide a controlled passage between the outlet 2e near nozzle 22 and the diaphragm chamber 44 or 44a. In Fig. l this is provided very simply by a passage 601: which leads off from passage 6il at a point above valve 62 and communicates with outlet and is controlled as to effective size by the manual valve 60e. In Fig. 2 an equivalent passage 60d extends from diaphragm chamber 44a to outlet 20, and is controlled as to effective size by manual valve 60e. In both of these arrangements a by-pass leads from the regulator delivery on the regulator side of the fuel orifice 22 at the venturi; and the manifold suction applied to the by-pass is limited by the valvular action of diaphragm 40 or 40a to the amount set, typically six inches of water. rIhe arrangement provides extra fuel for starting overand above that which would be otherwise provided. And the by-pass as so constituted, with limited depression applied to it, may be used either with or without the modiication of pressure which has been described in connection with diaphragm chamber 13a.

I claim:

l. In gaseous fuel feed systems for internal combustion engines and the like, the combination of a mixture passage having an outlet to an engine intake manifold, an air intake, and a venturi throat and a throttle between the intake and outlet; a gas pressure regulator comprising structure forming an outlet chamber, said structure including a valve operating diaphragm forming a wall of the outlet chamber and exposed on its'outer face to the' pressure in the air intake, a fuel passage connection be tween the outlet chamber and a fuel delivery at the Venturi throat; a valve-and-diaphragm system comprisingV a pressure regulating valve controlling gas oW from an initial inlet into the outlet chamber, said valve operating diaphragm, and connective means between the diaphragm and the Valve such that diaphragm movement toward the interior of the outlet chamber causes opening movement of the valve; means applying to the valve-anddiaphragm system a constant force acting in a valve closing direction and normally biasing the valve closed; means for permitting the pressure in the outlet chamber to be lowered during substantially all ranges of engine operation by the influence of the pressure at the intake manifold, means for limiting such influence throughout substantially al1 ranges of engine operation to a substantially constant amount, whereby the lowering of the pressure within the outlet chamber produced by the substantially constant influence causes a continuous, substantially constant force to be exerted on the diaphragm in a valve opening direction.

2. In gaseous fuel feed systems for internal combustion engines and the like, the combination of a mixture passage having an outlet to the engine intake manifold, an air intake, and a Venturi throat and a throttle between the intake and outlet; a gas pressure regulator comprising structure forming an outlet chamber, said structure including a valve operating diaphragm forming a wall of the outlet chamber and exposed on its outer face to substantially the pressure existent at the air intake, a fuel passage connection between the outlet chamber and a fuel delivery at the venturi throat; a valve-and-diaphragm system comprising a pressure regulating valve controlling gas ow from an initial inlet into the outlet chamber, said valve operating diaphragm, and connective means between the diaphragm and the valve such that diaphragm movement toward the interior of the outlet chamber causes opening movement of the valve; biasing means applying to the valVe-and-diaphragm system a constant force acting in a valve closing direction and normally biasing the valve closed; means for continuously deriving, from a point beyond the throttle, manifold depression from the mixture passage throughout substantially all ranges of engine operation, and means acting to limit that derived depression constantly to a substantially uniform value approximately not more than that of the manifold depression which occurs upon turnover of the engine to start with the throttle in closed position for idling; means permitting said limited depression to continuously apply to the valve-and-diaphragm system a force acting in valve opening direction and approximately equal to the force acting on said valve by said biasing means.

3. The combination defined in claim 2 and in which the depression limiting means comprises structure forming an auxiliary diaphragm chamber with an auxiliary diaphragm forming one of its walls, an annular valve seat member communicating with said auxiliary chamber and to which the manifold depression is applied, a depression limiting valve operated by the auxiliary diaphragm to move toward and onto the seat as said auxiliary diaphragm moves into its chamber, yielding means exerting a valve opening force on the depression limiting valve, the construction, arrangement and relative areas of the auxiliary diaphragm, the depression limiting valve and the annular valve seat member being such that a given pressure applied to both will cause the force exerted on the valve by the diaphragm to be of the order of several hundred times the force exerted directly on the valve by the same pressure and also being such that when depression limiting valve is seated and directly subjected to maximum manifold depression the total closing force on it is only slightly greater than when that valve is open, and whereby a substantially uniform constant depression is maintained in the auxiliary diaphragm chamber.

4. The combination defined in claim 3 and in which 7 8 thgigouiel-facejofsaidgauxiliarydiaphragmffisnexposed to ;k nection :that vwRiads between: the outlet; clafrarrdurevrV and.ih the-pressurefexistent =insadg outlet'chamber; vengurifthroat.

.5: The;comh'inafion dnedinf claim 3 f and iin; which References Cited in the 1,e{-)f ,d1is` ,patent f th@ivalvez-Qpenmgfmovementsof Yche regulator'dlaphragm y and th@ .lauxiliary diaphragm areuin;relativelylopposite 5' UNITED STATES PATENTS diriCfiQnS, 2,346,763 `Tonesv ....*ApL '18,v 1944iv 6.V Theombination defined in claim 3 andvinc1uding 2,3523003 ,"Poinsignon Iunef20,' 1944 also .manually-adjustable fpassage @means between the 2,563,228 Ensign Aug.: 7,.l951

auxiliaryrrdiaphr-agm chamber'f-an'ditheffuel "'.passagagon.V 2,597,335 Jones May:20, 1952

Claims (1)

1. 2. IN GASEOUS FUEL FEED SYSTEMS FOR INTERNAL COMBUSTION ENGINES AND THE LIKE, THE COMBINATION OF A MIXTURE PASSAGE HAVING AN OUTLET TO THE ENGINE INTAKE MANIFOLD, AN AIR INTAKE, AND A VENTURI THROAT AND A THROTTLE BETWEEN THE INTAKE AND OUTLET; A GAS PRESSURE REGULATOR COMPRISING STRUCTURE FORMING AN OUTLET CHAMBER, SAID STRUCTURE INCLUDING A VALVE OPERATING DIAPHRAGM FORMING A WALL OF THE OUTLET CHAMBER AND EXPOSED ON ITS OUTER FACE TO SUBSTANTIALLY THE PRESSURE EXISTENT AT THE AIR INTAKE, A FUEL PASSAGE CONNECTION BETWEEN THE OUTLET CHAMBER AND A FUEL DELIVERY AT THE VENTURI THROAT; A VALVE-AND-DIAPHRAGM SYSTEM COMPRISING A PRESSURE REGULATING VALVE CONTROLLING GAS FLOW FROM AN INITIAL INLET INTO THE OUTLET CHAMBER, SAID VALVE OPERATING DIAPHRAGM, AND CONNECTIVE MEANS BETWEEN THE DIAPHRAGM AND THE VALVE SUCH THAT DIAPHRAGM MOVEMENT TOWARD THE INTERIOR OF THE OUTLET CHAMBER

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