Gaseous fuel equalizing system for nonuniformly firing engines

2,683,084

July 6, 1954

O. L. GARRETSON

GASEOUS FUEL EQUALIZING SYSTEM FOR NONUNIFORMLY FIRING ENGINES Original Filed July 21, 1949

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Patented July 6, 1954

2,683,084

UNITED STATES PATENT OFFICE

2,683,084

GASEOUS FUEL EQUALIZING SYSTEM FOR NONUNIFORMLY FIRING ENGINES

Owen L. Garretson, Roswell, N. Mex.

Original application July 21, 1949, Serial No. 106,022. Divided and this application May 11, 1950, Serial No. 161,418

Claims.

This invention relates to carburetion systems for supplying gaseous fuel to internal combustion engines, and is directed to such systems that employ liquefied petroleum gas as a fuel, including improved pressure regulator and fuel delivery control apparatus for regulating the flow of gaseous fuel to the carburetor. This invention is a division of my pending application, Serial No. 106,022, filed July 21, 1949, and now abandoned, and is particularly directed to means for obtaining smooth, uniform operation on gaseous fuel burning engines during acceleration and during normal operation of engines having cylinders that fire at non-uniform time intervals.

A principal object of the invention is to correct for the effects of lag or inertia in the gas pressure regulating and supply means. Such effects are apparent during acceleration and are particularly noticeable in multi-cylinder internal combustion engines that are arranged so that the cylinders are fired at non-uniform intervals of time. In such engines when one of the cylinders initiates fluid flow in the induction system, the cylinder that fires immediately thereafter may receive a richer or a leaner mixture due to the lag or time delay inherent in gaseous fuel regulator systems, and different mixture strength which results in uneven power impulses from the cylinders.

Other objects of the invention are to accumulate a volume of gas during one portion of the cycle of an engine and deliver it to the intake manifold during the induction portion of the cycle, and to control the pressure head on the gas during its delivery so as not to interfere with the operation of the engine or of the regulating means.

The manner in which these and other objects and advantages are obtained will be apparent from the following detailed description of a preferred embodiment of my invention.

In the drawings, the figure is a semi-diagrammatic view of a preferred installation of a gaseous fuel system for internal combustion engines embodying the present invention.

Referring more particularly to the drawings, the device will be described as installed on a farm tractor powered by a liquid cooled internal combustion engine. Applicant employs a simple, semi-universal cylinder and regulator mounting arranged so that a comparatively few models of the mounting may be installed on a comparatively large variety of tractors. The mounting of the container including the mounting bracket are disclosed and claimed in my copending application, Serial No. 161,417, filed May 11, 1950, (CI. 48—184)

As seen in the drawings, the tractor T may have a radiator grill G behind which is the usual radiator R connected to the liquid cooling system of the engine for dissipating rejected heat 5 of combustion. Mounted by applicant’s novel bracket assembly A in front of the radiator is a high pressure container or cylinder it for a liquefied fuel gas, such as propane, butane and the like, or a mixture thereof.

The bracket A includes a platform 13 for the base of the container mounted on the tractor by a pair of rearwardly-extending arms (5. In a typical installation arms 15 may receive bolts 17 connected to the forward end portions of the side 15 beams 18 of the chassis of the tractor, or to any other suitable portion of the tractor chassis.

An upper clamping and steadying structure for the container is mounted upon the platform by braces 20 which support a plate 21 extending 20 from which are strap members 23 and a clamp device 24 holding the container in place, all as described in detail in my aforesaid pending application.

As seen in the drawings, in addition to the con25 tainer ID, the gaseous fuel system comprises a shut-off valve V, a high-pressure regulator H, a low-pressure regulator B, suitable piping, and an equalizer E. The construction and operation of the carburetor and regulator units of a preferred system is described in detail and claimed 30 in my copending application, Serial No. 161,419, filed May 11, 1950. The shut-off valve V has a hand wheel 42 for the opening and closing of the valve, and may be provided with a relief valve 43. A flexible hose 44 or the like connects 35 the valve V with the high-pressure regulator H which is provided with a pressure gauge 4® and a screw 47 for adjusting the regulator to the pressure desired. The high-pressure regulator H discharges gaseous fuel at a pressure somewhat 40 above atmospheric pressure into a low-pressure regulator or controller generally indicated at B.

Regulator B has upper and lower casing members 50 and 51 separated by a diaphragm 52, to form an upper fuel regulating chamber 53 to de45 liver fuel in accordance with engine demands, and a lower compensating air chamber 54 to maintain the desired air-fuel ratio. As shown in detail in my copending application, Serial No. 161,419, filed May 11, 1950, the regulator has an 50 inlet valve 56 opening into the upper chamber 53 and controlled by valve-actuating mechanism 57 mounted on the diaphragm 52. The inlet valve 56 is connected to the high-pressure regulator H as at 58 for reception of fuel therefrom.

An air bleed inlet orifice 60 is formed in the wall

2,383,084

1.

of casing 51 and an air outlet orifice 60α connects chamber 5S to pipe ill. Filter material 61 may be retained ovsr the orifice 68 by a cap 62 having an air inlet aperture 63. The orifice 68 is preferably smaller in area than the orifice 60α. ;

The upper chamber 53 of the regulator is connected to a fuel delivery pipe 101 which is connected to a pipe T (82. A pipe i93 has one end connected to the pipe T 102 and its opposite end connected to a fitting 10«. Fitting 10« is con- 1 nected to the Venturi throat 105 of the carburetor 188 of the engine by means of the gaseous fuel jet 197. A needle valve screw 108 is mounted in the fitting 164 for providing an adjustable restriction to the flow of gas from the pipe (S3 into j the carburetor.

The lower chamber 54 of the regulator is connected to &amp; pipe 1Π, the opposite end of which is connected to a second pipe T 112. A pipe 113 leads from the pipe T ! 1 ? and communicates with the ! carburetor 18S in what may be termed an intermediate pressure zone I, which zone preferably lies between the choke butterfly valve 114 and the Venturi throat 10S. An air intake pipe 1(4α is connected to the carburetor and in accordance with usual practice may lead to an air filter or similar air cleaning device. A throttle valve 115 is mounted adjacent the manifold end of the carburetor venturi for controlling the flow of the fuel mixture to the manifold 116.

Applicant’s novel equalizer device is generally indicated at Ξ. It comprises upper and lower housings ! 11 and 118, respectively, which are provided with out-turned annular flanges ! 1S and 120, respectively. A loose diaphragm 121 has its peripheral edge portion clamped between the flanges 119 and (20. The diaphragm 12! divides the equalizer E into an upper fuel gas receiving chamber 122 and a lower air receiving chamber 123. A nipple 124 connects the chamber 122 with the T-coupling 162 in the fuel line and a similar nipple 125 connects the chamber 123 with the Tcoupling 1! 2 in the compensating air line. The diaphragm 12! has sufficient slack to permit it to move freely between a position in which it is bowed into the chamber 122, and a position in which it is bowed into the chamber 123. The diaphragm 12! is preferably biased very slightly into the chamber 123, and in the illustrated embodiment this is accomplished by mounting the , equalizer E with the diaphragm horizontal so that its weight moves it into the chamber 123. Such bias, however, is not essential.

In its broader aspects the present invention is not limited to any particular type of regulator or to the interconnections by the pipes i I i and ! 13 between the equalizer chamber 123, the regulator chamber 154 and the carburetor inlet. The invention also includes, however, a novel combination of regulator and equalizer, the combination disclosed constituting the preferred embodiment.

In this combination, the orifice 60α opening into the regulator chamber 54 is connected by the pipes 111 and 113 with the intermediate zone I of the carburetor, so that the reduced pressures existing in zone I are applied to the chamber 123 and higher pressures of predetermined ratio to the pressures in zone I are applied to the chamber 54.

As previously stated, the equalizer E is intended primarily for use with engines having two or more cylinders with an uneven firing order but is also useful in connection with any type of engine to eliminate the effect of lag in the regulator during rapid acceleration or fluctuations in the intake velocity, and to permit the use of a less

6a sensitive regulator. For example, the disclosed embodiment of the invention may be used with a two-cylinder, four-cycle engine having the cylinders in line on the same side of the crankshaft with cranks displaced 180°. In such engines there is necessarily a shorter time interval between the firing of #1 and #2 cylinders than between #2 and #1 cylinders, the shorter interval being 180° of crankshaft rotation and the longer interval being 540° of rotation. Likewise, there is substantially continuous intake suction for the first 360° of rotation and none for the next 360' of rotation in the cycle.

The regulator B, regardless of its particular construction or the details of its operation, is designed to remain closed so as to prevent any flow of fuel through the valve 56 when atmospheric pressure exists in the carburetor 106. When the engine is running air is inspired by the cylinders on their intake strokes through the carburetor igg and the intake pipe i 14α. The flow of air through the pipe Ma and the air filter, if any, produces a pressure drop in the intermediate zone I which increases with an increase in the velocity of the air flow. A further pressure drop is produced by the restriction of the venturi IS5 which also increases with increasing flow, but at a greater rate than the increase of the pressure drop in the intermediate zone I. The pressure drop in the Venturi throat (05 is transmitted past the needle valve !08 through the pipes 103 and SOI to the regulator chamber 53 causing the regulator valve 56 to open so that fuel flows at a sub-atmospheric pressure through the jet i Of where it &gt; is mixed with the air stream in the Venturi throat 185 to provide a combustible mixture. Preferably, substantially all of the pressure drop between the regulator chamber 53 and the Venturi throat 135 occurs at the needle valve ! 88 and the regulator is governed so as to provide increasing amounts of fuel with increasing amounts of air flow through the venturi to maintain the desired mixture ratio throughout the operating

With the beginning of air flow through the Venturi throat i95, starting from atmospheric condition, the pressure drops in the intermediate zone I and this pressure drop is transmitted through the pipe ! (3 to the chamber 123 of the equalizer. While in the illustrated embodiment the chamber 123 is connected to atmosphere through the orifices 68 and 60α, these are made relatively small compared to the diameter of the pipes i i S and I i S so that substantially all of the pressure drop occurs through the orifices and the pressure in the chamber 123 remains substantially the same as the pressure in the intermediate zone I. At the same time the greater pressure drop occurring in the Venturi throat !05 is transmitted through the pipe 103 to the equalizer chamber (22 and through pipe ICi to the regulator chamber· 53. Before the pressure has dropped sufficiently to cause the valve 56 to open, the pressure in chamber 122 is less than that in the chamber (S3 so that the diaphragm !2i is urged upwardly into the chamber 122. As soon as the pressure drop transmitted through the pipe 10 i is sufficient to overcome the bias of the regulator valve towards closed position and the inertia of the regulator, the valve 56 opens to admit fuel into the line (01. However, so long as the pressure drop produced in the chamber (23 by a particular rate of flow through the intake pipe is less than the pressure drop required to be maintained in the regulator chamber 53 in

2,683,084 order to overcome the bias of the regulator towards closed position, the diaphragm 121 continues to be urged towards its upwardly bowed position in which the volume of chamber ί 22 is a minimum. With a regulator of given sensitivity, this condition exists at low rates of air flow through the carburetor, as when the throttle valve 115 is only slightly opened.

Under these conditions when the air flow through the carburetor stops, as it does after the intake period of the two cylinders in the type of engine described above, the pressures rise and approach atmospheric throughout the system. The inertia of the moving parts of the regulator permits the pressure in the regulator chamber 53 to rise beyond the regulated delivery pressure before the valve 5S is fully closed. Thus, the pressure in the regulator chamber 53 and in the pipes IΟ ί and 103 increases slightly above atmospheric pressure just as the regulator closes. In the absence of any correction, therefore, this positive pressure in the pipes 18 ί and 103 would cause gaseous fuel to flow through the jet 107 into the air at atmospheric pressure in the carburetor 106 and manifold I! 6. Thus, at the beginning of the next suction period an over-rich mixture would be delivered into the first cylinder if the engine were operating with the throttle valve 115 only slightly open or if the regulator had substantial inertia, since the amount of fuel permitted to bleed into the carburetor between suction periods would be a substantial percentage of the inspired charge for one cylinder.

However, with the present invention when the engine and regulator are operating under these conditions the increase of pressure in the regulator chambei· 53 and the pipes iBi and 103, as the regulator closes, moves the diaphragm 121 from its uppermost position toward its lowermost position, increasing the volume of the chamber 122. This increase in volume takes care of the extra fuel and prevents the pressure in the pipe !33 from rising above atmospheric pressure so that the fuel is not bled into the carburetor between the suction periods.

On the other hand, when the engine is operating with greater throttle openings producing relatively large pressure drops in the intermediate zone I and in the Venturi throat 105 compared to the pressure required to overcome the bias of the regulator towards closed position, when the suction starts the pressure in chamber 122 is lower than the pressure in chamber 123 in the same manner as described above until after the regulator valve 56 opens. As the suction continues to build up, however, the regulator delivers more gas at the regulated pressure while the pressure in the chamber i23 continues to fall until it is less than the pressure in the chamber i22 so that the diaphragm f2l is moved downwardly into chamber 123, charging the chamber 122 with gas. Under these conditions, when the suction stops, the chamber 122 being already fully charged cannot receive the additional amount of gas delivered by the regulator as it closes so that the pressure in the pipes 101 and 103 may become slightly positive and some gas may be bled into the carburetor through the jet 107. However, under these conditions of operation the amount of gas bled into the carburetor between suction periods is only a small percentage of the volume inspired by one cylinder and thus does not appreciably change the mixture ratio.

Thus when an engine of the type described including unevenly firing cylinders is operating either at small throttle openings or at full throttle openings the chamber 122, at the beginning of each suction period, is filled with gas and has a volume greater than its minimum volume, whether this charging of the chamber 122 occurred as a result of the inertia of the regulator in closing, or as a result of the change in the pressure relations during the previous suction period, as described above. Thus, at the beginning of each new suction period, gas is delivered by the equalizer chamber 122 into the line 103 as soon as the suction starts and before the pressure drop has become sufficient to open the regulator valve 56. At the same time that the gas is being delivered from the chamber 122, the regulator valve 58 begins to open so that fuel in the proper quantity is available to be mixed with the incoming air as soon as each suction period starts and throughout that suction period regardless of the extent of the throttle opening. This is particularly important when the engine is running at high speed or with the throttle fully opened since otherwise the first cylinder would be starved relative to the second cylinder because of the delay in getting the gas from the regulator to the Venturi throat while the first cylinder is inspiring its charge, which delay does not occur when the second cylinder continues the suction period.

In the particular pressure regulator arrangement disclosed, the high pressure regulator H may be set to deliver gaseous fuel to the low pressure regulator B at about 5 to 15 p. s. i. above atmospheric pressure. The low pressure regulator B is biased to hold the valve 56 closed under balanced pressure conditions and in the embodiment illustrated this is effected by arranging the regulator B with its diaphragm horizontal so that the weight of the diaphragm and the valve linkage 57 connected thereto is sufficient to hold the valve 56 closed against pressure of the gas from the high pressure regulator. Preferably the regulator is made sensitive to slight decreases in pressure in the upper or regulating chamber 53 so that the valve 56 is opened by the pressure drop in the Venturi throat 105 when the engine is turned over at cranking speeds.

During a suction period occurring in normal running of the engine the sub-atmospheric pressure existing in the zone I is not only transmitted to the equalizer chamber !23 but is also transmitted through the pipe I ί I to the orifice 6®a opening into the regulator chamber 54. However, the entire pressure drop existing in the zone I is not applied to the chamber 54 since atmospheric air is admitted to the chambei' 54 through the orifice 60 and flows into the pipe 11 ί through the orifice 60α so that a predetermined fraction of the pressure drop existing in the zone I is established in the regulator chamber 54 and applied to the underside of the diaphragm 52.

In one practical embodiment of the invention which has been found to operate satisfactorily the orifice 60α is made % of an inch in diameter and the orifice 60 is made A of an inch in diameter, the pipes ί i i and 113 being of substantially larger diameter so that substantially all of the pressure drop occurs at the orifices. With this arrangement about % of the pressure drop occurring in the intermediate zone I is applied to the chamber 54.

As the throttle I ί 5 is opened and the air speed through the carburetor increases an increasing pressure drop is applied to the pipe I i 3 and the same pressure drop, plus a further pressure drop produced by the Venturi restriction and increas2,688,084 s

head on the fuel is obtained in this manner it is unnecessary to vary the pressure in the equalizer chamber ί 23, and this pressure may remain atmospheric or substantially so, while the pressure 5 in the pipes (0( and 163 and in the chamber 122 varies above and below atmospheric with variations in the throttle opening.

Thus in the illustrated embodiment of the invention, the pressure at which gas contained 10 in the chamber 122 is delivered to the pipe i G3 at the beginning of a suction period is always subatmospheric, and falls as the suction increases. This is because the pressure acting on the gas in the chamber 122 is the pressure in the chamber 15 123 less the weight of the diaphragm 12 i, and the pressure in chamber (22 falls with the pressure in the zone I of the carburetor as the air velocity therethrough increases. At the same time, the pressure in chamber 54 of the regulator 20 B is reduced a lesser amount, by about threefourths of the pressure drop in the zone I and the chamber (23 in the example given, so that the difference between the pressure in the chamber 54 and the delivery pressure of the gas from 25 the chamber (22, which difference increases with increasing suction, acts in a direction to open the regulator valve 56.

Stated in another way, as the air velocity through the carburetor builds UP from zero to the 30 maximum permitted by the particular throttle opening, the pressure head on the fuel delivered from the chamber (22 past the needle valve (63 builds up with the difference between the pressure drops in the zone I and the Venturi throat 35 (65. less the force required to overcome the slight bias of the diaphragm i 2 i and the inertia thereof; and at the same time the pressure head available to deliver fuel from the regulator B past the needle valve (88 builds up at a. faster rate, in 40 accordance with the difference between the pressure drop in the Venturi throat (05 and a fraction, such as three-fourths, of the pressure drop in the zone I, less the force required to overcome the bias of the regulator diaphragm 52 and the inertia thereof and of the valve operating linkage 57 connected thereto. Thus the pressure heads start at the same time and build up simultaneously. Because of the lower bias and inertia of the diaphragm (2( fuel is delivered from the chamber (22 before the regulator valve 56 opens while before the suction has attained its maximum value in the case of relatively wide throttle openings, the differential pressures on the diaphragm. 52 have become sufficient to open the -.- regulator valve B6 and fuel is delivered from the ^Ot&gt; regulator at a higher pressure head. The delivery of fuel from the regulator to the pipe ! 8 i at a pressure higher than the pressure in the chamber (23 reverses the pressures acting upon the _6U diaphragm (2! so that this diaphragm moves downwardly into the chamber (23 whether or not all of the fuel gas contained in the chamber (22 had been delivered to the pipe (93.

Thus the action of the equalizer E in delivering _GS fuel contained therein into the fuel line leading to the carburetor does not interfere either with this action of the regulator or with the proper action of the engine since the fuel is delivered at a rate to maintain the proper mixture ratio. -₀ Tn case the throttle opening and the sensitivity of the regulator B are so related that the difference between the pressures in the chambers 54 and 123 is not equal to the amount required to overcome the bias of the regulator 58 towards 75 closed position, the equalizer chamber (22 de- ing at a faster rate is applied to the jet 107. Only a slight pressure differential between the chambers 53 and 54 is required to overcome the bias of the regulator valve and open the valve 5S to admit gaseous fuel from the high pressure regulator H into the regulator chamber 53. The valve automatically opens and closes to admit the proper amount of fuel to maintain this slight pressure differential between the two chambers 53 and 54. Thus as the pressure in the Venturi throat ί 05 decreases with increased throttle openings and consequent increased rates of air flow, the pressure drop between the chamber 63 and the discharge end of the jet (67, most of which occurs at the valve 183, increases while the pressure in the regulator chamber 54 remains a slight amount higher than the pressure in the regulator chamber 53, just sufficient to overcome the bias of the regulator valve towards closed position.

The pressure head on the air entering the throat of the venturi, which head determines the amount of air which flows into the Venturi throat and is mixed with the fuel entering through the jet (07, is not the difference between atmospheric pressure and the pressure in the Venturi throat, but on the contrary is the difference between the pressure in the zone I at the entrance to the venturi and the pressure in the throat. The pressure in zone I is always less than atmospheric pressure when the engine is running, and decreases as the throttle opening increases. Thus if the pressure in the regulator chamber 54 were made equal to the pressure in zone I at all throttle openings, the pressure head applied to the fuel would be equal to that applied to the inspired air at all throttle openings. However, due to the fact that the ratio of the specific heat of air at constant pressure to its specific heat at constant volume is greater than the corresponding ratio for liquefied petroleum gas, such as propane and butane and mixtures thereof, the mixture would become slightly leaner with increased flow if exactly balanced pressures were maintained, since the weight of fuel inspired would not increase in constant ratio with the weight of air inspired. Thus to maintain a constant mixture ratio it is necessary to increase the pressure head on the fuel at a rate slightly greater than the rate at which the pressure head on the air entering the Venturi throat increases with increasing throttle openings.

In addition, it is desirable from the standpoint of fuel economy to enrich the mixture slightly to the ratio for maximum power at full throttle opening, and lean it to the mixture ratio producing maximum economy at small throttle openings. Accordingly, the orifices 69 and 63α are selected to apply a percentage of the pressure drop in zone I to the chamber 54, so that the pressure head on the fuel delivered by the regulator to the needle valve !@8 increases with increased throttle opening at a greater rate than the pressure head on the air while the pressure in the equalizer chamber 123 varies with the pressure in zone I.

Part or all of the desired increase in the pressure head on the fuel with respect to the pressure head on the inspired air may also be obtained by the mounting of the regulator valve 56 for reciprocation in the fuel inlet passage, as illustrated, and as disclosed more in detail in my said application Serial No. 161,419, filed May 11, 1950, so that the regulator valve restricts the fuel passage, producing a pressure drop acting to open the valve and increasing with increasing rates of flow. When the entire variation of the pressure

33,084 chamber and an air chamber separated by a movable pressure responsive element, a .connection between said equalizer fuel chamber and said fuel conduit upstream from said adjustable 5 restriction for conducting fuel to and from said equalizer fuel chamber, and a conduit for connecting said equalizer air chamber to the intake pipe of the engine upstream from the venturi therein, said conduit being constantly open for 10 free flow of air into and out of said air chamber whereby movement of said pressure responsive element in response to differential pressures in said chambers creates flow of air through said conduit so that the pressure in said air chamber 15 is substantially unaffected by movement of said pressure responsive element.

3. In a gaseous fuel system of an internal combustion engine having an air intake pipe and a gaseous fuel conduit opening into said pipe, an 20 equalizing device comprising a fuel receiving chamber· and a control chamber, a loose diaphragm sealed between said chambers, said diaphragm being subjected to the fluid pressures in said chambers and being movable into and out of 25 said chambers to vary the volume thereof, a passageway for connecting said fuel receiving chamber with the fuel conduit connecting a source of fuel to the engine, and a passageway for connecting said control chamber with the air 30 intake pipe of such engine, both of said passageways being constantly open for free flow into and out of said chambers whereby movement of said diaphragm in response to differential pressures in said chambers creates flow of air through said 35 control chamber passageway so that the pressure in said control chamber is substantially unaffected by diaphragm movement.

4. In a gaseous fuel system of an internal combustion engine having an air intake pipe and a 40 gaseous fuel conduit opening into said pipe, an equalizing device comprising a fuel receiving chamber and a control chamber, a movable pressure responsive element subjected to the fluid pressures in said chambers and movable into and out of said chambers to vary the volume thereof, a passageway for connecting said fuel receiving chamber with the fuel conduit connecting a source of fuel to the engine, and a passageway for connecting said control chamber with the intake pipe of such engine, both of said passageways being constantly open for free flow into and out of said chambers whereby movement of said pressure responsive element in response to differential pressure in said chambers creates flow of air through said control chamber passageway so that the pressure in said control chamber is substantially unaffected by movement of said pressure responsive element.

5. An equalizing device for a gaseous fuel system of an internal combustion engine having an air intake pipe and a gaseous fuel conduit opening into said pipe, comprising a fuel receiving chamber and a control chamber, a movable pressure responsive element subjected to the fluid pressures in said chambers and movable into and out of said chambers to vary the volume thereof, said element being biased into said control chamber by a substantailly constant force, a passageway for connecting said fuel receiving chamber with the fuel conduit connecting a source of fuel to the engine, and a passageway for connecting said control chamber with the intake pipe of such engine, both of said passageways being constantly open for free flow into and out of said chambers whereby movement of said pressure responsive

S,6i livers all of its contained fuel to the pipe 103 and the pressure in the pipes 103 and (01 thereafter falls sufficiently to complete the opening of the regulator valve. In such cases, however, the pressure in the chamber 122 does not exceed the pressure in the chamber 123 during the suction period and the chamber 122 contains only the small amount of fuel with which it was charged as a result of the inertia of the regulator in closing after the previous suction period. Nevertheless, the operation of the engine is improved since the lag between the end of the delivery of the fuel from the chamber 122 and the beginning of the delivery from the regulator is less than it would have been if the differential pressures on the regulator diaphragm had not started to build up during the period the equalizer chamber (22 was discharging.

Thus, the equalizer, which is a compact, and simple device, and which may be quickly and easily installed, has the smoothing attributes of a very large reservoir on one hand, and yet on the other hand does not reduce the sensitivity of the regulator as would such a reservoir.

As an example of a typical installation with a two-cylinder, four-cycle engine of about 200 to 500 inches displacement, and with a regulator constructed in accordance with the above specific example, the system operates satisfactorily with an equalizer diaphragm of about six or seven inches in diameter.

While a preferred embodiment of the invention has been disclosed in considerable detail, it is to be understood that the invention is not limited thereto, and that numerous changes and rearrangements of parts may be resorted to without departing from the scope of the invention as defined in the following claims.