US2169487A

US2169487A - Carbureting apparatus

Info

Publication number: US2169487A
Application number: US102718A
Authority: US
Inventors: Roy F Ensign
Original assignee: Ensign Carburetor Co
Current assignee: Ambac International Corp
Priority date: 1936-09-26
Filing date: 1936-09-26
Publication date: 1939-08-15
Anticipated expiration: 1956-08-15

Description

Aug. 15, 1939. I

R. F. ENslGN CABBURETING APPARATUS- Filed Sept. 26, 1936 5 Sheets-Sheet l Aug. l5, 1939.

R. F. ENSIGN CABBURETING APPARATUS Filed Sept. 26, 1936 `3 Sheets-Sheet 2 Aug- 15, 1939- R. F. ENslGN 2,169,487

CABBURETING APPARATUS agorney Patented Aug. 15, 19,39

UNITED STATES CARBURETING APPARATUS Roy F. Ensign, San Marino, Calif., assignor to Ensign Carburetor Co., Ltd., Huntington Park, Calif., a corporation of California Application september 26, 193s, serial No. 102,718

7 Claims.

This invention pertains generally to fuel feeding and carbureting apparatus for internal combustion engines, and in one of its more specic major aspects deals with Aapparatus for supplying engines with gaseous fuel at substantially constant pressure and at variable rates in conformity with the requirements of the engine under different conditions of operation. The invention also contemplates the provision of a carbureting apparatus which may operate selectively on either gaseous or liquid fuel.

With particular reference to that aspect of the invention dealing with the supply of and carburetion with natural gas or other forms of gas for the operation of internal combustion engines, my objects, generally, are threefold: First, to regulate the pressure of the gas fed to the carbureter so as to maintain substantially constant pressure under all loads, preferably a pressure close to or slightly under atmospheric pressure; second, to produce the correct mixture of gas and air for the engine under all speed and load conditions; and third, to make it possible to obtain a perfect mixture during cranking of the engine and initial operation up to the point where normal operating conditions obtain, The latter object is particularly stressed because of the diiculties heretofore involved in starting. In order that a more comprehensive understanding of the difficulties which are overcome by the invention may be had at the outset, it may be Well to refer briefly to the conditions giving rise to the problem and how, in general, the invention provides the solution.

In order to obtain the required volume of mixture to meet the power requirements with a gas carbureter the venturi must necessarily be relatively large and consequently the fuel metering depression therein at cranking or idling speeds is not sufcient to .give a continuous proper proportioning of the fuel and air mixture. In accordance with the invention, I overcome this difilculty by providing means whereby during cranking or idling speeds, the engine may be supplied with the correct amount of gaseous fuel without having to depend on the normal Venturi depression at these speeds, thereby overcoming the above mentioned difculties.

The present gas carbureting apparatus is generally similar to that described in a copending application, Ser. No. 26,768, led June 15, 1935 by O. H. Ensign on Gas pressure regulator, now Patent No. 2,073,298, March 9, 1937, but dilers essentially with reference to the means for obtaining proper fuel mixtures at starting and idling speeds. I'he O. H. Ensign application embodies generally the combination of a differential gas pressure regulator and gas carbureter, and in that apparatus an amount of gas flow to the carbureter sufficient for starting purposes is produced by a manually operated priming device causing the pressure regulator to deliver gas independently of pressure conditions in the suction passage of the carbureter. While that type of priming device has proven satisfactory in many different types of installations, in others it has to some extent proved less efficient than the corresponding means embodied in the present invention, due to the fact that where the carbureter includes pipe connections to an air cleaner, these connections and the cleaner itself become filled with gas at starting, excluding the air and requiring considerable cranking to thin the fuel and air mixture being taken into the engine to the desired ratio at engine starting speed. Theoretically, of course, it would be possible to prime the regulator just sufficiently to deliver the correct amount of gas, but in practice such exactness of control is difficult, and usually the result is that, where the engine is cold, combustion occurs irregularly because the improperly proportioned fuel mixture does not have suicient energy upon combustion to shear the oil lms on the cylinder walls and to continue to operate the engine while it is still cold.

Viewed in one aspect, the invention may be regarded as providing for two stage carburetion to supply a combustible mixture of the proper proportions lrst at starting speeds,4 and then as the engine warms up, for normal operating speed. Briefly, the rst stage carburetion is accomplished by providing within the suction passage of the carbureter a manually operated valve, independent of the throttle, which obstructs the suction passage and thereby creates a depression which causes the gas to ow from the regulator, such gas being delivered to the suction passage at the inlet side of the throttle through a severely restricted opening which is, in effect, imposed in the path of flow simultaneously with the operation of the valve. The second stage carburetion is effected by relieving the suction passage of the obstruction imposed by the said manually operated valve and by delivering to the suction passagea ow of gas under control of the throttle which is properly restricted for the normal oper- 'ating requirements.

It is also an object of the invention to provide a carbureter capable of operating on either liquid or gaseous fuel. In accomplishing this object I A2 A YProvideseparate nqid'ndgasmeln 'l charging into the suction passage of the carbureter at the inlet side of the throttle, a suitable fuel feeding system for supplying liquid fuel from a constant level supply chamber to the liquid fuel nozzle, a pressure regulator for Supplying gaseous fuel at substantially constant pressure to the gas fuel nozzle, separate controls wherebyv the carbureter may operate selectively on liquid or gaseous fuel.

In this latter connection the invention contemplates as a further object, the provision of a float locking mechanism which will prevent wear in the parts when the carbureteris being operated on gas and the liquid supply unit is shut off.

Relative to the combination gas and liquid carbureter, my invention also contemplates gas feeding attachment which can readily be mounted on a standard liquid fuel carbureter to convert the same to a combination unit adapted for operation with either liquid or gaseous fuel All the above mentioned features and objects of the invention, as well as further aspects and def tails thereof, will be best understood from the nism and showing the shutter valve in normal .operating position;

Fig. 3 is an end view of the air intake'illustrating the choke valve construction contemplated by this invention; i

Fig, 4 is a fragmentary section on line 4-4 of Fig.v 5 is a view generally similar to Fig. 1, showing a combined gasoline and gas carbureter. the y gas pressure regulator being shown in elevation;

Fig. 6 is a sectional view showing a variational form of carbureter adapted to operate on either gasoline or gas;

Fig. 7 is a section on line 1--1 of Fig. 6;

Fig. 'la is a fragmentary section on the line laf-1a of Fig, 6; p

Figs. 8 and 9 are fragmentary sections on lines 8-8 and 9-9 of Fig. 6;

Fig. 10 is a fragmentary section on the line III-I0 of Fig. 9; and y Fig. 11 is a diagrammatic view illustrating means for simultaneously actuating the gas and liquid .control valves in a combination unit so that the selective supply of gaseous and liquid fuels is automatically controlled,

In Fig', 1 I show a gas fuel supply system comprising a pressure regulator, generally indicated at I0 for feeding gas at substantially constant, and preferably subatmospheric pressure, to the carbureter .I I. It will be understood that in its broad aspects, the invention is not limited to the use of a pressure regulator or carbureter of any particular construction, or` built according to the details shown in Fig. l, but that any suitable regulator and carbureter combination, may be used so long as they contain parts in the operative relationships specified in the claims.V The particular apparatus illustrated has however, been found especially suited to the purposes of the invention', and hence may be regard-ed as representing a preferred construction.

I have illustrated a simple form comprising a suction or fuel and air mixing passage composed of sections I2 and I3 connected together by screws I4, section I2 being attached to the engine manifold fuel and air intake I5. A venturi I6 is placed in the suction passage be- 4twenfthe 4inlet l1 and outlet Is, a mam fuel nozzle I9 discharging into `the throat of the venturi under control of the usual throttle 20. Further details of the carbureter will be later 'described in connection with their operative relationships with thev pressure regulator I0.

`For amorecomplete` discussion of the operation of pressure regulator I0, reference may be had to the patent of O. H. Ensign, referred to hereinabove, anda relatively brief description of the regulator details and operation will suillce for present purposes. The regulator body comprises Vthree sections 2I, 22 and 23 between which are clamped the main and pilot diaphragms 24 and 25.' Pressure chambers 26 and 21 are provided Y below and above main diaphragm 24, the last mentioned chamber being defined by a transverse wall 28 within the intermediate body'section 22.

Chamber 29 above the pilot diaphragm 25, constitutes a reference pressure chamber whereby at all times a relatively constant pressure is ap` plied to the upper surface of the diaphragm. The chamber 30, below the diaphragm, which is proof carbureter vided with a partition plate 3I held in place by an expansible. lock ring 32, constitutes a variable pressure chamber,

High pressure gas supplied to the regulator from inlet 33 is deflected by a baille 34 into chamber 26, from whence it passes under control of the main regulator, valve 35 to the regulator outlet 36. The latter connects by way of pipe 31 with a fuel supplypassage 38 formed within section I3 of the carbureter, the gas flowing from passage 38 under control of the mechanism, (to be described hereinafter) to nozzle I9 via passage 38. Main regulator valve 35 is attached to the main diaphragm 24 byy lock ring 40 retaining the flanged head 4I of the valve stem 42 within a connecting member 43 fastened to the diaphragm. Upward movement of the diaphragm is resisted iby 'springs attached to the diaphragm and atmospheric pressure, and, by reason of the regulator being operated by suction communicated from the carbureter, will automatically shut off the gas supply to the carbureter as soon as such suction is discontinued when the engine stops.

A restricted iiow of gas is permitted from the inlet 33 to chamber 21 above the main diaphragm by way of bushing 45 having a small calibrated orifice, and passage 46, these passages normally serving to balance the pressures applied to the'.

opposite sides of the main diaphragm. In order to avoid or dampen out excessive'vibrations of the main diaphragm with resultant irregularities in the movement of valve 35 and in the outlet n pressure, chamber 21 is placed in communication with a closed chamber 41 via orifice 48.

The operation of the main diaphragm 24 and the consequent actuation of the valve 35 was discussed in detail in connection with Fig. 4 of the copending O. H. Ensign patent herein- -above referred to. It suflices to say that when a positive suction is established in the fuel supply passage 38 that such suction is communicated through connections 3l and 36 and the passage indicated at 50-50 into the variable pressure chamber 30 below the pilot diaphragm 25 by way of a port 5|. Port 5| is a restricted port and is located between the pilot diaphragm 25 and the plate 3|. In addition to this port 5| the variable pressure chamber is provided with a substantially unrestricted port indicated at 52, such port is located'beneath the plate 3| and also communicates with the passage 50--50'.

The suction thus communicated to the variable pressure chamber 30 establishes a pressure differential between the two sides of the pilot diaphragm 25, such differential being effective to depress this diaphragm. When the pilot diaphragm 25 is thus depressed, it is effective to actuate the pilot valve mechanism generally indicated by reference numeral 53, structural details of which are also fully described in the copending O. H. Ensign patent hereinabove referred to. The minimum depression which will actuate the regulator to deliver gas therefrom is set by the size and compression valve of the spring 53 in the valve mechanism 53. The opening of the pilot valve 53 under the action of a depression in chamber 30 communicates the suction from the lower part of chamber to chamber 2l at the upper side of the main diaphragm 23, causing such diaphragm to be elevated with the result that the main valve 35 is opened.

in order to accommodate for any pressure fluctuations at the air intake, which may occur due to the use of air cleaners or otherdevices, and to. maintain a uniform pressure balance in the carbureting system at all times, it is preferable that the reference pressure chamber 29 above the pilot diaphragm 25 be connected to the air inlet passage il rather than being opened to the atmosphere. For the purpose of establishing this pressure communication, the section 23 above the pilot diaphragm is shown as being formed with a passage 55 which is connected through a tting 56 and a tubing 57 with a pilot tube 58 which extends into the inlet end of the air passage.

For proper idling operation it is important that a positive suction be communicated to the variable pressure chamber 30 during such idling operations. This suction must be of suficient magnitude to hold the main valve 35 open the required amount to supply gas for a proper combustion mixture and is obtained by establishing a communication between the variable pressure chamber 30 and a region of the air intake passage beyond the throttle in or adjacent an engine manifold connection l5. For this purpose, the carburetor section l2 is provided with a wall passage 60 which communicates with the main air passage through a control orifice 5|. The passage 6D is connected through the fittings generally indicated at 52 with an adjusting screw chamber 53 on the top section 23 of the regulator. This adjusting screw or adjusting valve chamber 53 is equipped with a needle valve 56 which communicates with a horizontal chamber 55, such chamber opening into the top of passage 50 which has the ports 5| and 52 therein communicating with the variable pressure chamber. With this arrangement, it will be seen that on closing down the throttle to the correct idling speed, the regulated suction through 6|, 60 and 62 to the valve 64 and through such valve to the variable pressure chamber 30 causes the pilot diaphragm to lower just the correct amount to supply the idle fuel. Such an arrangement is important in a regulator of this character, due to the fact that, with the full size venturi required for maximum power, the amount of gas drawn through the nozzle I9 when idling with the choke wide open is'not easily regulated.

Through the use of the passages and connections just described, a portion of the idle suction is transferred to the under side of the pilot diaphragm and is bled by the passages 50 and 50' which compensate for the violent suction above the orifice 6|. The foregoing is also set out in said O. H. Ensign patent.

As has been previously pointed out it is one of the principal objects of this invention to provide a gas carbureter of the general character described above with means for supplying a combustible mixture of the proper proportions during cranking or starting speeds. For the satisfaction of this object, my invention contemplates the provision of a choke valve 68 which is shown as comprising a conventional disk valve mounted across the intake end of the air passage upon a shaft 69, the outer end of which is equipped with a levermember 'l0 for its manual actuation. The choke disk 68 is shown as being provided with an air orifice '|2. 'When the valve 68 is closed, as is done during cranking operation, the suction created at this speed is sufficient to draw a relatively small volume of air through the orilce 12.

In order that the Yproper amount of gas may be supplied to the air intake passage while the choke is closed and the air is being drawn through the restricted orifice '|2, it is important that the ow passage for the gas between the chamber 38 and the main air passage be likewise restricted. The restriction of the gas ow may be accomplished in various ways, but it is important for more satisfactory operation, that the restriction employed here be made adjustable to accommodate for different` types of fuel. In the form of my invention, which is shown in Figs. l and 2, this is accomplished by completely cutting 01T the inlet opening to chamber, 39 through the medium of a shutter valve generally indicated at 74, which in effect interposes a relatively severely restricted orifice 'l5 as the only passage between the chamber 38 and the interior of chamber 39. The orifice l5, which may be termed a starting orifice, is equipped or associated with a needle valve 716 adjustable to control the flow therethrough. And while the passage 39 may have been referred to herein as a relatively unrestricted passage, it will be understood that an adjustable restriction is provided for the purpose of controlling the flow of gas therethrough. This last mentioned restriction is shown as comprising an adjustable valve member generally indicated by reference numeral (see Fig. 2).

The shutter valve 'i4 is shown as comprising an elongated plate slotted as indicated at 80 and supported by a pivot 8|, which extends through the slot. The plate ld is biased upwardly toward the seating surface surrounding the bottom of passage 39, by means of a compression spring 52, supported by a washer 83 and a key 84 in me bottom f the pivot pin al. This valve u must be actuated simultaneously with the openingland closing movements of the choke valve 5l' and i'or the purpose of effecting such movement, the choke shaft 69 is equipped with a collar 85, which carries a pin 86, such pin engaging in an opening 81 in vvalve plate 14.

For the purpose of holding the valve plate 14 in its two extreme positions of adjustment, illustrated in full lines and dotted lines in Fig. 2, a compression spring is interposed in the slot 80 between the pivot pin 8| and the rear end of the slot. a

During starting operations the choke'68 is closed manually by means of the lever 10, such operation placing the shutter valve 14 over the lower end of the gas nozzle chamber 39, thereby closingthe same. The throttle is' then opened to about the position shown in Fig. 1 and upon cranking the engine there will be a positive suction of air through the orifice 12 and of gas through the orifice 15. The suction thus supplied in the gas chamber 38 will be positively communicated to passages 50--50 and through the port 5| to the under side of the rpilot diaphragm 25. This suction, applied in the variable pressure chamber below the pilot diaphragm, will depress the diaphragm and consequently actuate the pilot valve to ultimately open the main valve 25 in the manner previously described thereby supplying gas for the operation of the engine.

As soon as the engine has turned over for av short period, the choke lever 10 is turned to immediately throw the choke valve 68 into its open position, it being preferred that no intermediate position be used. The opening of the choke valve 68 simultaneously opens the shutter valve 14 so that gas is then delivered to the air passage directly through the bottom openingof chamber 39 in which the valve 11 has been properly adjusted for normal operating conditions.

It has been previously pointed out as an additional object of this invention, to provide a carbureter capable of operating on either liquid or from the regulator, generally indicated by reference numeral |011.. The regulator is supplied with gas 'through a valve indicated by reference numeral 33a, which may be sel'ectivelyopened or closed to supply the carbureter with gas or liquid fuel as may be demanded by the particular l operating conditions. N The'regulator is the same as that shown at I0 in Fig. l, and for that reason is illustrated in outside elevation.

Gas is supplied tothe throat of the venturi |6a through a gas tube |9a, mounted in a gas chamber 39a, such chamber incorporating a shutter valve 14a, which is operated in conjunction with the choke valve 68a in the same manner as was described in connection with Fig. l. The regulator is also equipped with a gas pressure balance connection, generally indicated by reference numeral 51a and an idling connection generally indicated by reference numeral 62a.

liquid fuel la supplied to the throat of the venturi'through a jet 89 from a constant level.

intake 9| in the fuel chamber housing into the fuel chamber itself, is controlled by suitable valve means as indicated at 92, such valve means being of conventional construction, and being actuated by a float lever 93, which carries a float 93 on its free end, and is pivoted in the housing'as indicated at 94.

The present form of liquid fuel supply unit for the combination gas and liquid carbureter shown in Fig. 5, is illustrated merely "for the purpose of describing my invention, and is the same as that disclosed land described in the P. W. Ensign patent, No. 1,863,195, issued on June 14, 1932, and for a detaileddescription of this liquid fuel sup-` ply unit, reference is made to that patent. Fork the purpose of describing the present invention, it will be sufficient to point out that the section |2a, which contains the venturi of the air passage, also includes the idling by-pass, accelerating well, etc., indicated by reference numeral 95, The liquid fuel chamber 90 contains a block 96 which includes primarily the ports and passages for controlling the initial metering of the liquid fuel from the supply reservoir to the main fuel passage 91, which communicates with the jet 89.

The space above the liquid level in fuel reservoir 90 is closed against direct communication with the atmosphere, and suitable means is provided whereby the pressure in the air intake |1a is applied to the fuel in the reservoir. In this embodiment of my invention, the inlet pressure is communicated to the fuel reservoir by a passage comprising an annular chamber |00, which surrounds the upper end of the elbow section l|311. The annular chamber |00 communicates with the inlet |1a of the main air passage, through a'substantially unrestricted passage indicated at |0|, the passage 0| having an opening in the air passage |1a on the intake side of the choke valve 68a. The annular chamber |00 communicates with the fuel chamber above the liquid level therein through a passage shown in dotted lines at |02 and a port |02'.

Fuel is taken from the reservoir into a vertical riser passage |03 in block 96, such passage comprising ay portion of the main fuel passage, by way of a valve controlled orifice |04 in the end of plug |05, which is screwed into a bore within the bottom of the block. The flow through the orifice |04 is controlled throughk the medium of a needle valve |05, which is urged upward into engagement with a screw cap |06 by means of a spring |01 confined between the upper face of the block and a ange |08 on the upper end of the valve. The fuel admitted to the riser passage |03 through the valve controlled orifice flows upwardly and over the lower edge of an unrestricted opening ||0 into passage and from there itpasses downwardly to the horizontal main fuel passage 91. A restricted flow of air is also taken into the passage l|03 through a calibrated bushing ||I3 at its upper end, the fuel and air being mixed in flowing through the openy ing and the mixture is conducted downeration of the liquid unit of this combination carbureter, reference is again made to the P. W. Ensign patent hereinabove referred to, and at this time it is again emphasized that my invention does not contemplate or require the use of any specic liquid fuel supply unit. Asa matter of fact, it is an important and novel feature of the invention that the gas supply unit described above may be employed as an attachment for a conventional liquid carbureter to convert the same to a combination unit. In this regard, my invention contemplates the replacement of the air intake section of a conventional liquid fuel carbureter with a section corresponding to the elbow I3 or |3a, which has a gas supply passage formed of a length such that its outlet opens substantially in the throatportion of the venturi.

In a combination carbureter of this character, it is important that means be provided for avoid- 'ing undue wear in the parts of the liquid unit of the carbureter when the carbureter is being operated with gas fuel. It is also important that means be provided for shutting 01T the liquid unit so that the combination carbureter can be selectively operated on gas or liquid, such carbureter being provided with a valve for shutting oi the gas supply indicated at 33a, referred to hereinabove. For the purpose of shutting off the liquid supply unit and further to lock the float and the float control valve against vibration when the liquid fuel supply unit is shut ofi, I employ a float locking mechanism, generally indicated by reference numeral |20. This mechanism embodies a bushing |2l, threaded into a suitably formed boss |22 on the liquid fuel chamber housing 90, such bushing being internally threaded to receive a threaded adjusting stem 12d which is equipped with a thumb nut |25. The upper end of this adjusting stem bears against a plunger member |26, which carries a compression spring |21, engaging the under surface of the oat lever 03 at its upper end. It will be seen that the adjusting screw |24 may be advanced upwardly in its threads to raise the oat lever into a position where it will lock the valve 92 in closed position, the spring |21 being compressed under this action to lock the float against vibration when the valve 92 is thus closed. In the form described above, the gas control valve and the liquid control mechanism are illustrated as being independently operated. It may be preferable under some conditions of operation to interconnect the gas and liquid controls so that the one is automatically shut oil when the other is opened; one fom of such connection is diagrammatically illustrated in Fig. l1 and will be referred to in detail later in the description.

In Figs. 6 to 10, inclusive, I have shown another modified form of a combination gas and liquid carbureter of the special down-draft type. In this connection it should be understood that the forms as shown in Figs. l and 5 can be used either down-draft or up-draft by simply turning the whole carbureter element over. Referring to Fig. 6, the main air passage is shown as being comprised of sections |30, |3| and |32, the throttle valve indicated by numeral 20h, being located in section |32, and the choke Valve 68h being situated in the section |30.

The gas passage 31h leading from a regulator similar to that shown in Fig. 5, communicates with a cylindrical valve chamber |34, which contains a cylindrical valve |35, attached to the choke shaft 69h. This cylindrical valve |35 is cut away on one side, as indicated at |31, to provide an opening which normally leads to the gas inlet chamber |38-|38'. The portion |38 of this chamber has an opening |39 communicating with the throat of the venturi |6b, and contains a screw valve |40 for restricting the gas flow, the required amount for normal operating condition.

The choke valve 68h is providedwith' an orifice 12b, and when the choke valve is closed, it will be seen that the air is drawn into'the suction passage through this orifice. Simultaneously with the closure of the choke valve 68h, it will also be seen that the skirt portion of the cylindrical valve |34 rotates around to close the passage leading to the gas supply chamber |38. The closure of the main opening in passage |38 in this manner, in effect interposes between the connection 31h and the passage or chamber |38-|38' a restricted passage indicated generally by reference numeral 15b.

'I'he passage 15b, as shown in Figs. 7 and '70, embodies a control chamber |43, communicating with chamber |38 through a port |43', the control chamber |43 being in communication with the connection 31h through a passage |44-|44. The control chamber |43 carries a needle valve generally indicated by reference numeral |45, which is employed to control the restricted oW of gas through the restricted passage 15b during starting operations, such needle valve adjustment corresponding to the adjustment shown in connection with the valve 16 in Fig. 2.

In this embodiment of my invention, a Pitot tube 58h enters the intake connection 11b on the inlet side of the choke valve 68h and connects through pipe 59h to the upper side of the diaphragm in a suitable regulator, similar to that shown in Fig. 5, for the purpose of maintaining a pressure balance on the pilot diaphragm in the manner described in connection with Fig. 1.

The idle opening @Ib is connected through a connection 62h to idle adjustment valve means similar to that indicated at 63 in Fig. l.

The liquid supply unit for the carbureter is shown as comprising in a general way, a float chamber portion |50 cast on one side of the section 13|. In this portion |50 is assembled the liquid or gasoline carbureter parts. A oat |5I is attached to a iloat lever |52 pivoted at |53 and adapted to close the oat valve, indicated generally by reference numeral |54. Fuel enters the connection |56 through the passage |55, and hows through the openings |56 to the valve seat.

The liquid fuel flows from the float chamber |53 through a fuel orice |60, which is equipped with an adjustable needle valve 6| for controlling the ow therethrough. Needle |6| is adjusted by operating the milled head |62, such head being associated with a spring 4|63 interposed between the under side of the head and the top of the adjustment needle.

The liquid unit is equipped with a riser passage (best illustrated in Fig. 9) which embodies a tube |10, and passages |`l| and |12, the tube |10 being restricted as indicated at 13. The tube |10 takes out of the well chamber |65 at its lower end, thus drawing up the fuel to the chamber |11 which is provided with an air vent |15, equipped with an adjusting screw valve |16. The leg |12 of the idle passage terminates in a chamber |11 which, as illustrated in Fig. 10, communicatesV An economizer passage |80 connects from thev air in-the upper portion of the float chamber to a chamber |8I, which has a bore |82 connecting with the throttle tube at a point above the edgev ofthe throttle disk when it is in its closed position. This economizer operates to cause a` slight Ydepression on the surface of the gasoline in the float chamber over that portion-of the load which may be under throttle control, beginning slightly above idle.

For the purpose of locking the vibration, and to also lock the float control valve in closed position when the carbureter is being operated on gas alone, I provide an adjusting screw |90, which is shown as beingv mounted in a bushing mounting |9|, -such screw carryingl a compression spring |92 and a plunger |93, which contacts a cross member |94 on the float lever mechanism below the lower end |54f ofthe iloat` valve. With this arrangement it will be-seen that the float and float valve may be locked in avalve closing position, so that there is no wear inthese parts due to vibration of the engine vwhile-the v" "delivering gas at 'substantially constant pressure Y to said suction passage, said gas delivery meansl including a'relatively severely restricted starting carbureter is being operatedwith gas alone,"v

A pressure balance is maintained on top of the liquid in the float chamber through a passage," such passage `opening into the top of the fioat chamber and having a port |91 c :on'imunicat'ing- 'with the air inlet portiony of thesi'lctionpassage!' As was previously stated in connection with.v Fig. 5, my invention contemplatesthe `p'ro's'fision' of means for interconnecting the gas inl'etcon'- trol valve 33a and the float and float valve lock'- ing mechanism |20 so that when one connectionis opened the other is automatically closed: 'n. Fig. 11, I have shown one form of vconnection which may be employed for this'purpose. In this.

construction the gas inlet connection 33e is shown as being equipped with a disk va1ve`200 mounted on a shaft 20|, the extending endv of which carries a lever 202.- The float lever 93c and the valve 92e are adapted to be urged upwardly into a locked position by a plunger member 203, which is slidably mounted through suitable packing means ina bushing |2|c. The bottom of the plunger 203 `is attached to a bell crank 200, pivoted on a suitable bracket as indicated at 205. The other arm of the bell crank 204 is attached by means of a link 206 to the lever 202.

A tension spring 201 is provided for the purpose of urging th'e linkage system to one` of its extreme positions. In the form shown, the spring 201 holds the'gas valve 200 closed and depresses the plunger l203 so that the float and oat valve are free to operate. An operating link or rod 209 is provided for controlling the position of these two valve means. Thus when it is desired to operate on gas, the rod 209` is drawn forward in the direction of thev arrow A to open the gas valve 200 and lock the float valve. Suitable latching means 2|0-2|| may be provided for locking ,the rod 209 in this latter position.. When thev latch 2|0-2II is released the valve and float locking mechanism are drawn back to the other extreme position (shown inl full lines) by the action of the spring 201.

It is to be understood that while I'have here described and illustrated certain preferred emy float against limited to the precise details of constructionor theparticular 'combination of parts described above, Abut includes within its scope whatever reter including a suction passage connecting with an engine manifold and having an air inlet, an outlet and a throttle for controlling the flow of iluids through saidsuction passage; means for f' delivering gas atvsubstantially constant pressure to saidsuction passage, said gas delivery means including a relatively severely restricted starting orifice and a relatively less restricted normal operating' orifice; a choke valve in said suction I passage at the inlet side of the 'point of fuel discharge from said fuel delivery orices; means for closing said choke valve; a fuel controly valve actuated with saidchoke valve for closing said normal operating orifice; and means for admitting a restricted flow of air to said suction passage when said choke valve is closed.

-2. The combination comprising: a gas carbureter including a suction passage connecting with an engine manifold and having an air inlet, an outlet and a throttle for controlling the flow of fluids through said suction passage; means for orifice and a relatively less restricted normal operating orifice; a choke valve in said suction paslvalveaLctuated with said choke valve for closing said normal operating orifice.

l3. The combination comprising: a gas carbureter including a suction passage connecting withv an engine manifold and having an air inlet, an

outlet and a throttle for controlling the flow of iluids through said suction passage; a pressure v regulator having a gas intake and an outlet communicating with said suction passage, said regulator operating to deliver gas to the carbureter at substantially constant pressure, said regulator outlet being communicable with said suction passage by way vof a fuel delivery passage; a choke valve in the suction passageat the inlet side of the point of fuel discharge from said fuel delivery passage; a fuel control valve operated in accordance with movements of said choke valve to control the ilow of fuel through said delivery passage, saidfuel control valve closing said delivery pas-- sage when said choke valve is in closed position; and means for delivering to said suction passage at the outlet side of the choke valve, a restricted flow of fuel when said fuel control valve is in closed position. 1

4. The combination comprising, a gas carbureter including a suction passage connecting with an engine manifold and having an air inlet,an outlet and a throttle for controlling the flow of fluids through said suction passage; a pressure regulator having a gas intake and an outlet communieating Withsaid suction passage, said regulator operating vto deliver gas to the carbureter at vsubstantially constant pressure, said regulator outlet being communicablewith said suction passage by way of a fuel delivery passage; a choke vvalve in the suction passage at the inlet side of the point of fuel discharge from said fuel delivery passage; a fuel control valve operated in accordance with movements of said choke valve to control the iiow of fuel through said delivery passage, said fuel control valve closing said delivery passage when said choke valve is in closed position; and means for delivering to said suction passage at the outlet side of the choke valve, a restricted flow of fuel when said fuel control valve is in closed position, said choke valve having a relatively small air passing opening.

5. The combination comprising; a gas carbureter including a suction passage connecting with an engine manifold and having an air inlet, an outlet and a throttle for controlling the flow of fluids through said suction passage; a venturi at the inlet side of the' throttle; a pressure regulator having a gas intake and an outlet communicating with said suction passage, said regulator operating to deliver gas to the carbureter at substantially constant pressure; a fuel nozzle discharging into said venturi, said nozzle being communicable with said regulator outlet by way of a fuel delivery passage; a choke valve in the suction passage at the inlet side of said venturi; a valve operated in accordance with the movements of said choke valve to control the ow of fuel through said delivery passage; and means for delivery to said suction passage at the outlet side of the choke valve a restricted flow of fuel when said fuel uids through said suction passage; a pressure regulator having a gas intake and an outlet communicating with said suction passagesaid regulator outlet being communicable with said suction passage by way of a fuel delivery passage; a choke valve in the suction passage at the vinlet side of the point of fuel discharge from said fuel delivery passage; a fuel control valve operated in accordance with movements of said choke valve to control the flow of fuel through said delivery passage, and means for delivering to said suction passage a restricted flow of fuel when said fuel control valve is in closed position.

7. The combination comprising: a gas carbureter including a suction; passage connecting with an engine manifold and having an air inlet, an outlet and a throttle for controlling the flow of fluids through said suction passage; a pressure regulator having a gas intake and an outlet communicating with said suction passage, said regulator operating to deliver gas to the carbureter at substantially constant pressure; a fuel nozzle in said passage; a manually operated choke at the inlet side of said nozzle; means including a fuel passage for feeding gas to said nozzle; a valve movable with said choke valve to control the flow of gas through.A said fuel passage, and means for feeding to said suction passage a restricted ilow of gas when the last mentioned valve is in closed position.

ROY F. ENSIGN.