US2689172A - Engine fuel gas metering device - Google Patents

Description

Sept. 14, 1954 s, P. JONES ENGINE FUEL GAS METERING DEVICE 2 Sheets-Sheet l Filed Dec. 18, 1952 INVENTOR S a m .J on e s 5 ACTUAL @.H. P.

ATTORNE v Sept. 14, 1954 5, P, JQNES 2,689,172

1 'lllllll e u 1| HA 4 Patented Sept. 14, 1954 ENGINE FUEL GAS METERIN G DEVICE Sam P. Jones, Dallas, Tex., assigner to .I & S Carburetor Co., Dallas, Tex., a corporation of Texas Application December 18, 1952, Serial No. 326,700

3 Claims.

This'invention relates to new and useful improvements in engine fuel gas metering devices.

In internal combustion engines having only a few cylinders, such as one and two cylinder engines, some diiculty has been experienced in metering the fuel gas supply properly to the intake manifold. This is especially true of fourcycle engines where the manifold pressure is employed as the load indicating means and is utilized to regulate the. fuel gas supply. Since engine `speed does not necessarily indicate engine load, the pressure in theintake manifold of the engine is the most widely employed factor for controlling fuel gas supply. In a one or two cylinder, four-cycle engine, however, a depressed manifold pressure exists only during the suction stroke of the engine, and throughout substantially the entirety of the other three cycles the pressure in the intake stack of the engine as well as vthe intake manifold thereof, is substantially atmospheric. Hence, the manifold pressure is indicative of the loading of the engine only during the suction stroke, and to afford encient engine operation, the engine loading must be sensed during the suction stroke and the fuel metered accordingly. Metering devices are mechanical structures andv cannot' operate instantaneously. For this reason, it has been found extremely difficult, if not virtually impossible, to provide a device which would respond to manifold pressure te meter' the fuel gas and' would respon-d suinciently quickly to accomplish this desired result during the very short period the manifold pressure is depressed. As a necessary compromise such'fuel metering devices have necessarily been set rathery rich in order to insure adequate fuel supply to the engine, and there has necessarily been a wastage of fuel with the net result that the engine does not display as much economy in fuel consumption Vas would be desired.

It is therefore, an important object of this invention to provide an improved metering device for the'fuel' gas of engines which is responsive to manifold pressure to meter fuelV to the engine, and which,V upon actuation during the suction stroke ofthe engine both senses and retains the degree of depression of the manifold pressure whereby the fuel gas metering structure is held substantiallyl at the ldesired setting throughout all four strokes of the engine during a single cycle, l"

and' thus renders of no effect the inability of mechanical devices to respond instantaneously to a pressure change.

[another important object of the invention is to provide a device of the character described having also means for slowly bleeding ofi the pressure depression received and retained during the suction stroke of the engine whereby the metering structure is constantly readjusted in accordance with the loading of the engine and brought into the proper condition for metering fuel in proper yet economical quantities to the engine as the demand of the engine for such fuel may vary.

A particular object of the invention is to provide an improved metering valve for metering fuel gas to internal combustion engines, the valve having pressure responsive means for actuating the same and reducing the availability of fuel as the manifold pressure depression increases, there being a conductor between the pressure-responsive means and the intake manifold of the engines with a check valve therein whereby pressure depression may be communicated to the pressureresponsive means from the intake manifold, but the dissipation of the reduced pressure condition acting upon the pressure-responsive means being prevented by the check valve; and further, having restricted pressure bleed means for by-passing the check valve and permitting an increase of the pressure acting on the pressure-responsive means.

An additional object of the invention is to provide a device of the character described which is particularly adapted for Vuse with two cylinder engines having two intake stacks and which may readily be incorporated into the conventional twobarrel carburetor' or gas mixer.

Yet another object of the invention is to provide a device of the character described which will effect an appreciable economizing of fuel over the intermediate load ranges of one and two cylinder, internal combustion engines.

A construction designed to carry out the invention will be hereinafter described together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings, wherein examples of the invention are shown, and wherein:

Fig. l is a longitudinal, sectional View showing a device constructed in accordance with this invention connected to the intake stack of an internal combustion engine,

Fig. 2 is a transverse, sectional view showing a modification of the invention connected to the intake stacks Yof a double-barrel carburetor,

Fig. 3 is a graph illustrating the fuel economy of this invention as compared to the economy of g a conventional fuel gas metering device, the two curvesbeing plottings' of specific fuel' consumption in pounds of fuel per brake horsepower per hour plotted against actual brake horsepower being delivered by the engine,

Fig. 4 is a longitudinal, sectional view illustrating a modification of the invention applied to a two barrel carburetor,

Fig. 5 is a transverse, vertical, sectional view taken upon the line 5-5 of Fig. 4, the view being enlarged,

Fig. 6 is a longitudinal, sectional view taken upon the line 6-6 of Fig. 5,

Fig. 7 is an enlarged, fragmentary, transverse sectional view of one of the check valve structures, and,

Fig. 8 is a horizontal, sectional view taken upon the line 8-8 of Fig. 7.

In the drawings, the numeral I designates the air intake stack of a carburetor or fuel mixer for internal combustion engines. The carburetor may be of the single intake stack or single barrel type, as shown in Fig. 1, or may be of the two or double barrel type, as shown in Fig. 2. The intake stack is provided with the usual Venturi section II having projecting thereinto a fuel feed pipe I2, and the usual throttle valve I3 is situated downstream of the Venturi section. This structure is connected to the intake manifold (shown in dotted lines at I4 in Fig. 1) of the internal combustion engine to which the fuel mixture is to be supplied. It is quite conventional to use a single barrel carburetor, as shown in Fig. 1 upon single cylinder engines and to employ a double barrel carburetor, as shown in Fig. 2, on two cylinder engines. i

A metering valve structure is connected to the intake stack and includes a suitable tube I5 having an inlet nipple I6 adapted to receive a flexible hose or other conductor through which the fuel is supplied. The fuel inlet nozzle I2 is connected by a fuel conductor or pipe I1 to the bore of the tube I5, communicating therewith through one side wall. A suitable sleeve valve I8 is slideably mounted within the bore of the tube I5 and is provided with a lateral port I9 adapted to register with the tube I1 to permit the flow of fuel to the nozzle I2. Obviously, axial movement of the member I8 within the tube I5 will uncover a greater or lesser area of the bore I1, and hence, the axial position of the member I8 as it reciprocates within the tube I5 will control the quantity of fuel supplied through the air intake stack I0.

For controlling movement of the valve member I8, the tube I5 is flared at one end to form a dished portion 2D having a marginal outwardly extending flange 2 I. A dished cover plate 22 having a central, cylindrical dome 23 and an outwardly extending marginal ange 24, is connected by the flange 24 to the flange 2I, and a flexible diaphragm or pressure responsive member 25 is clamped between the flanges. Suitable bolts 26 may be used for joining the flanges together.

The valve member I 8 is of sleeve-like construction and has an open end 21 facing the inlet nipple I6, and a closed end 28 abutting the diaphragm 25. The diaphragm is clamped to the closed end of the valve sleeve by means of a plate 29 and screws 30. A coiled spring 3I is positioned within the dome 23 and conned between the closed upper end of said dome and the plate 29 so as to constantly urge the diaphragm toward the inlet end of the tube I5. This action simultaneously moves the valve sleeve I8 into the position shown in Fig. 1 in which the port I9 is in full registry with the bore of the tube I1 and the metering valve structure is open to its fullest extent. A

4 stop bolt 32 is threaded into the top of the dome 23 and extends therethrough toward the plate 29 so as to limit movement of the plate and the diaphragm, along with the valve sleeve I8, toward a closed position. A lock nut 33 is provided for holding the bolt 32 in its adjusted position.

The air intake stack is provided upon one side wall with a boss 34 through which a passage or pressure conductor 35 extends to the interior of the cover plate 22. The passage 35 is enlarged at 3B adjacent the bore of the stack I0, and a check valve ball 31 is positioned within the enlarged portion so as to function as a check valve and prevent the flow of fluid under pressure from the intake stack through the passage 35. There is also provided a passage 38 bypassing this check valve structure and having therein a restricted portion 39 of very small diameter. The function of this restricted bypass conductor arrangement will be described more fully hereinafter.

In the operation of this form of the device, and assuming the engine not to be in operation, atmospheric pressure will exist throughout the intake stack and the counterbore 36, and through the bleed passage 39, will be established in the bore 35. Hence, the spring 3I will be effective to move the diaphragm away from the cover plate 22 and will aline the port I9 fully with the bore of the tube I1. As the engine is started, and assuming the throttle valve I3 to be nearly closed, a relatively high vacuum will be established downstream of the throttle valve, and this vaccum will be communicated through the counterbore 36 since the same opens into the intake stack downstream of the throttle valve. This vacuum will lift the valve ball 31 and be communicated through the passage 35 to the diaphragm 25 and pull the plate 29 against the stop bolt 32. At this point, the port I9 will be misalined with the tube I1 to its greatest extent and the flow of fuel to the intake stack will be at a minimum. In this idling condition of the engine the proper fuel mixture may be obtained by adjustment of the bolt 32 so as to open the metering sleeve valve formed by the tube I5 and the sleeve element I8 to the minimum desired extent.

It is to be noted that this vacuum or low pressure created within the intake manifold by operation of the engine exists in reality only during one stroke of each cycle or approximately 25% of the time. If no means were provided for preventing such action, the spring 3| would force the metering valve to its wide open position during the remaining three quarters of each cycle with the net result that an excessive flow of fuel would be encountered at least during the initial portion of the intake stroke, and excessive usage of fuel would result.

The check valve 31 and bleed passage 39 prevent this occurrence, however, the check valve functioning to hold the metering valve in a partially closed position and preventing air or gas from entering the passage 35 so as to relieve the partial vacuum established within the space dened by the diaphragm and the cover plate 22. At the same time, the restricted by-pass passage 39 prevents the indefinite retention of this condition, and fluid will gradually bleed through it around the check valve so as to bring the pressure conditions within the aforesaid space into agreement with the manifold pressure existing during the suction stroke.

As the throttle valve is opened, and the load r upon the engine is increased, it is desirable that more fuel be fed to the intake stack, and this aeearva also occurs reason of the :check naive and .restricted bleed passagestructure. Asthe engine load increases, the vacuum the intake marn- .told' decreases, and unless this "vacuum is. greater than thatexisting within the passage 35, the check valve will not lifted from its seat. Instead, a gradual ow of fluid through the rrestricted passage .39 ltakes .place and' the pressure exerted upon the .fliaphragln sbronght into agreemern:` with the manifold pressure. A :reduction ofthe suction acting :on the :diaphragm in opposition to the :spring 31 permits the diaphragm 'to move the metering valve :toward a more openposition `and to increase .the fuel flow as required.. 'This .action continues as the throttle `valve is moved to a rull open position, at which point, the .spring `3l is effective to move the-.metering valve to .its full lopen position and to supply the maxim-um yquantity of 'f-uel. `Anytime the load on the engineis reduced fand the throttle valve is closed, there twili be exerted `during the suction stroke of the engine a vacuum or reduced pressure which will lift the valve ball 311` from its seat, communicate this partial vacuum to the diaphragm 25., and .shift the metering valv-e into the position ldeterminedby the degree of vacuum exerted. Vl/henevor` the throttle valve is opened wider, the `check valve ball 3-1 remains seated and pressure equalization takes place at a con-- trolled rate through the restricted passage '39 to permit fur-ther openin-g of the metering valve.

The rdevice thus functions somewhat as a time delay mechanism and slows the lresponsiveness of `the metering valve to an extent sufficient to hold the valve in an adjusted position throughout a full cycle of operation -of the engine. hs the engine 'load is increased or decreased and the manifold pressure varies accordingly, this pressure is communicated in a ccntrolledm'anner tothe diaphragm 25 to vary the setting of the metering valve accordingly, `and at the same time, the metering valve is protected against the rapidiy fluctuating pressures existing downstream Iof the 'throttling 'valve occasioned bythe connection. of only one or two cylinders of an engine to the intake stack.

'This type of carburetor depends upon the flow of air through the intake stack to create "a reduced pressure Varea or zone within `the venturi Il, and by means of this reduced pressure, to

draw fuel through the nozzle `f2 from the source of fuel supply. The degree oi ysuction exerted through the nozzle |2 does not vary 'in strict accordance, however, ywith the iiow of air through the venturi. At low engine loa-ds, the air velocity through the venturi is low andthe suction exerted through the fuel nozzle I2 may be `inadequate to supply suihcien-t fuel. At intermediate loa-ds, the structure may he nicely in bala-nce, but at high loads where the air velocity through the venturi is high, too much suction may be exerted through the nozzle and hence, too rich a fuel mixture may be supplied. It has been lcommon practice heretofore to provide multiple 'barrel carburetors to overcome this objectionable feature, land hence, even in .a two cylinder engine, `a double-barrel' carburetor may be employed. Since each barrel intake stack supplies one of the engine cylinders, the lproblem in .such an installation in properiy sensing the manifold pressure and applying the same to regulate the fuel supply may be quite .as severe as that encountered .in a single cylinder engine having a single barrel carburetor. The present .invention lends` itself readily to utilization of a double-barrel carburetor as shown 'in Eig. '12. En this .iform of the invention, uel :is admitted through 'the inlet fend f4!! `:of 'an elongate metering valve :tube 2M, fand pipes for conductors 4t2 extend through the 'side wall Eof the tube All to the Ifuel intake nozzles 43 fof 'the two air intake :stacks 44. A 'valve .sleeve A5, similar to the sleeve I8 is .'s-lidably mounted within *the tube 4a and is provided `-with a pair of lateral ports 4'6 adapted to .register vwith the bores of the tubes 42.. A diaphragm and .spring :structure substantially the same .as that Yshown in Fig. l :is enclosed with 4a housing .4T :connected `to one rend o the tube 41, and this housing is in `turn connected to the air inta-ke lstacks order to respond to the manifold pressure exerted downstream l'o'f the throttle valve. Aswill appear more ifuliy herein ait'er, this metering valve structure also responds to engine load 1'conditions and diiiers `from -tlf-1e form of the invention shown in Fig. `1 primarily by 'metering fuel to two intake Vstacks rather than a :single intake stack. The operation is substantially identical.

Since the 'air intake stacks of double barrel carburetors are often formed in a vsing-le integral unit, this 'invention may Jdesirably be applied thereto as shown in Figs. `4 to l8. As illustrated 'in these figures, there is provided a carburetor 'body 48 having'theren va pair of parallel barrels Ior intake stacks 49. Each oi the intake stacks 'is ,formed with a Venturi section 50 into which 'a gas ini'et nozzle Si extends. The conventional choke 152 is provided upstream oi the venturi and 'the throttle valve for throttle plate 53 is mounted downstream ofthe Venturi section.

The tube 41 -oi Fig. "2 is clamped directly to the side of the body 48 and secured thereto 'by a block 54 and bolts 55. The diaphragm housing Il is carried upon one end of the tube 1H, and the opposite end thereof, is, or course, adapted to be connected to the source of `fuel supply by `the nipple 4i). 'The tube 4I extends transversely of the axes -of the intake Istacks in the manner illustra-ted in Fig. v2, and a hose yor other suitable conducting member 56 extends from the ydiaphragm housing il for Aconnection to the intake stacks.

-Sinee these carburetor bodies are conventiona=lly `Formed with flan-ges at each end for ready attachment 'to an air Icleaner or other device (not shown) at the intake end, and to the intake manifold of the engine at the 'downstream or outlet end, the lconnection of the hose 56 into the intake stacks may desire-bly be made through the downstream flange. As shown in Figs. 4 and 6, the body @8 'is provided with an outwardly extend-ing iiange '57 at its outlet or downstream integrally `with said flange and with the carburetor body at a point intermediate the two intake stacks. Areeess 5-9 is drilled vor otherwise formed in the 'boss 5B and extends upwardly at an angle therein. The recess carries internal screw threads El) which receive a screw-threaded nipple 6i to which the hose '56 is connected.

-On each side oi the recess 59 are formed screwthreaded bores 62, extending vertically upwardly through the lower edge of the fiange 51 and communicating at their upper ends through reduced passa-ges 63 with the interiors of the intake stacks di! downstream of the throttle valves 53.-. Anguiar passages 64 provide communication between the recess t9 and the rbores 362.

A screw-threaded check valve plug 65 is received in each of the bores 32. Each of the plugs 65 4h-as an axial screw-threaded bore lSli in its upper end closed by plugs El hav-ing a plurality of eccentrically-positioned, longitudinally-extending, iiow passages 68. The lower ends of the bores 66 are free of screw threads to form cylindrical chambers 68 receiving check valve balls 10, and the lower extremity of each of the chambers 69 communicates through an axial passage 1| with a bore 12 extending transversely of each of the plugs 65. A valve seat 13 formed in the bottom of each of the chambers 69 receives the valve balls 10 whereby the latter may close off flow through the passages 1| and 12.

The outer periphery of the plugs 65 are cut away to form annular grooves 14 around the plugs and the passages 12 open into said grooves. As shown in Figs. and '7, when the plugs 65 are positioned within the bores 62, the grooves 14 register with the passages 64, and thus, communication is established from the recess 59 through the branch conductors formed by passages 64 and the grooves 14, as well as the passages 12 and 1i of each of the plugs 65, and the remaining passages leading to the stacks 49. There is further provided in each of the plugs a very small, restricted passage 15 extending radially from the chambers 69 to the grooves 13. Since the inner ends of the restricted passages 15 are above the valve seats 13, said restricted passages remain in communication with the intake stacks at all times through the passages 63 and 68.

The operation of this modification of the invention is the same as that previously given, the ball and seat 13 performing in the same manner as the check valve ball 31, while the restricted passages perform the function of the restricted passage 39 of the form of the invention shown in Fig. 1. The particular structure illustrated is beneficial in that the check valve plug structures 65 are readily accessible and may be easily removed and replaced as desired. Thus, plugs having different diameters of restricted passages 15 may be substituted in any particular carburetor structure, the check valve structure may be removed for cleaning, repair, or replacement, or for cleaning out of the passages 63 and 64.

The improved performance of the present invention as compared to conventional devices is graphically illustrated in Fig. 3 of the drawings by fuel consumption curves obtained on dynamometer tests of a commercial two-cylinder engine operated with its conventional carburetor, and of the same engine operated with a carburetor constructed in accordance with this invention. The engine under test was a 35 H. P. engine and the fuel consumption of the engine, using L. P. G. fuel was determined in pounds per brake horsepower per hour for each of the two carburetors over the entire operating range of the engine. The upper, solid-line curve A is a plot of the results obtained during testing of the engine with its conventional carburetor. The lower, dotted-line curve B is a plot of the fuel consumption observed when the engine was operated with a carburetor constructed in accordance with this invention. These two curves show clearly that although the two carburetors resulted in approximately the same fuel consumption at full load and under idling conditions, appreciable fuel savings were obtained in the intermediate load ranges Where such engines operate a large percentage of the time. Using as an example, an engine load of 25 brake horsepower which may be considered an average loading for engines of this type, a reduction in fuel consumption of approximately 0.08 of a pound of fuel per brake horsepower per hour is shown. In a ten-hour operating day, this means a fuel saving of approximately four gallons of L. P. G. fuel. Comparable fuel economy was observed in the range from l5 to 30 brake horsepower loading of this 35 H. P. engine. The fuel economy resulted from the ability of the carburetor constructed in accordance with the invention to respond accurately to the engine manifold pressure during the suction stroke of the engine whereby fuel could be metered to the engine in accordance with the requirements therefor, and whereby both excessive and/or insufficient supplies of fuel to the engine were avoided.

The foregoing description of the invention is explanatory thereof and various changes in the f size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. A fuel gas metering device for an internal combustion engine having a fuel intake connected to an air intake stack with a throttle valve therein, said device including, a fuel conductor for supplying fuel to the engine fuel intake, a metering sleeve Valve connected into the fuel conductor, said valve having a movable valve sleeve reciprocable to open and close the valve, a diaphragm connected to the valve sleeve for reciprocating the sleeve, the diaphragm having one side enclosing a chamber within which the application of a sub-atmospheric pressure will bias the metering valve toward a closed position, a spring biasing the valve toward an open position, a pressure conductor connected between the chamber and a point in communication with the air intake stack between the throttle valve and the engine intake, a check valve in the pressure conductor arranged to open only when the pressure in the chamber is greater than the pressure at said point, and a by-pass conductor communicating between the chamber and a point in communication with the air intake stack between the throttle valve and the engine intake, the by-pass conductor being arranged in parallel with the check valve so as to by-pass the same and having a restriction therein.

2. A fuel gas metering device for an internal combustion engine having an intake connected to a pair of air intake stacks with throttle valves therein; said device including, a metering sleeve valve carried by the intake stacks and extending transversely across the exteriors of said stacks, fuel conductors opening into the interior of the sleeve valve and extending into each of the stacks, a valve sleeve slideably mounted in the valve and having ports adapted to be alined with the fuel conductors, means for supply fuel gas to the ports, pressure-responsive means connected to the valve sleeve for reciprocating the same in the valve, the latter means enclosing a chamber Within which the application of a sub-atmospheric pressure will bias the valve toward a closed position, means biasing the valve toward an open position, a pressure conductor leading from the chamber, a. pair of branch pressure conductors, each of the branch conductors communicating between the first pressure conductor and a point in communication with one of the air intake stacks between the throttle valve thereof and the engine intake whereby the first conductor is placed in communication with both `a check valve in each of the branch air intake stacks through said branch conductors, conductors opening away from the first pressure conductor, and a restricted orifice in each of the branch conductors arranged in parallel with the check valves and by-passing the latter.

3. A fuel gas metering device as set forth in claim 2, wherein the intake stacks have a marginal ange for connection to the engine intakel the ange having formed therein the branch conductors and having a recess in communication with the branch conductors, the rst pres sure conductor being connected into said recess, plugs removably positioned in the branch conductors and extending vertically in the flange from the exterior thereof, the check valves being gravity closing and carried by the plugs so as to be removable from the exterior of the ange,

the plugs having exterior annular grooves in communication with the recess and the metering valves sides of the check valves, and the restricted orices being formed in the plugs and i extending from said grooves to the intake stack sides of the check valves.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. A FUEL GAS METERING DEVICE FOR AN INTERNAL COMBUSTION ENGINE HAVING A FUEL INTAKE CONNECTED TO AN AIR INTAKE STACK WITH A THROTTLE VALVE THEREIN, SAID DEVICE INCLUDING, A FUEL CONDUCTOR FOR SUPPLYING FUEL TO THE ENGINE FUEL INTAKE, A METERING SLEEVE VALVE CONNECTED INTO THE FUEL CONDUCTOR, SAID VALVE HAVING A MOVABLE VALVE SLEEVE RECIPROCABLE TO OPEN AND CLOSE THE VALVE, A DIAPHRAGM CONNECTED TO THE VALVE SLEEVE FOR RECIPROCATING THE SLEEVE, THE DIAPHRAGM HAVING ONE SIDE ENCLOSING A CHAMBER WITHIN WHICH THE APPLICATION OF A SUB-ATMOSPHERIC PRESSURE WILL BIAS THE METERING VALVE TOWARD A CLOSED POSITION, A SPRING BIASING THE VALVE TOWARD AN OPEN POSITION, A PRESSURE CONDUCTOR CONNECTED BETWEEN THE CHAMBER AND A POINT IN COMMUNICATION WITH THE AIR INTAKE STACK BETWEEN THE THROTTLE VALVE AND THE ENGINE INTAKE, A CHECK VALVE IN THE PRESSURE CONDUCTOR ARRANGED TO OPEN ONLY WHEN THE PRESSURE IN THE CHAMBER IS GREATER THAN THE PRESSURE AT SAID POINT, AND A BY-PASS CONDUCTOR COMMUNICATING BETWEEN THE CHAMBER AND A POINT IN COMMUNICATION WITH THE AIR INTAKE STACK BETWEEN THE THROTTLE VALVE AND THE ENGINE INTAKE, THE BY-PASS CONDUCTOR BEING ARRANGED IN PARALLEL WITH THE CHECK VALVE SO AS TO BY-PASS THE SAME AND HAVING A RESTRICTION THEREIN.

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