US2338910A - Change-over carburetor - Google Patents

Description

Jud. 11, 1944. J. REMERsoN 2,338,910

CHANGE-OVER CARBURTOR Filed Aug.` 25, 1941 5 sheets-Sheet 1 5 Sheets-sheet 2 Jan. 11, 1944. J, R EMERSON 2,338,910

CHANGE-OVER cARBUREToR Filed Augyzs. 1941 5- sheets-sheet s JUL 11, 1944 J. R. EMERSON 2,338,910

CHANGE-OVER CARBURETOR Filed Aug. 2s, 1941 5 sheets-sheet 5 ufo/n Enezom/ Patented Jan. 1l, 1944 CHANGE-OVER CARBURETOR John R. Emerson, Flint, Mich., assignor to Borg- Warner Corporation, Chicago, Ill., a corporation of Illinois Application August 23, 1941, Serial No. 408,028

3 Claims.

This invention relates to multiple fuel carburetors and particularly to an improved carburetor of this type for selectively feeding either a volatile fuel such as gasoline or a heavier fuel such as an oil or distillate.

It is an object to provide an improved arrangement responsive to manifold suction for selectively operating the valves controlling the supplies of the respective fuels. It is a more particular object to provide such an improved arrangement wherein there is no mechanical connection between the throttle valve assembly and the respective fuel supply valves. It is a still more detailed object to provide such an arrangement of means under the control of the throttle valve operable in accordance with the position of said valve for regulating the valve for regulating the vacuum control means in accordance with the position of the throttle, there being no mechanical connection between ysaid throttle and said vacuum means.

It is another object to provide a novel manually controlled selective arrangement for either; (l) locking the vacuum responsive means in gasoline or volatile fuel supplying position; (2) for locking the vacuum responsive means in 01T or neutral position wherein neither gasoline nor distillate can be drawn into the carburetor; (3) for locking the vacuum responsivle means in distillate supplying position; or (4) for releasing the locking means altogether, rendering the vacuum responsive means effective to operate either the gasoline supply Valve or the distillate supply valve depending upon the degree of vacuum.

Still another object is the provision in an assembly of the present type of arrangement of means for preventing undesirable pulsations of the vacuum responsive means.

A further object is the provision of an improved arrangement of means for urging the vacuum responsive means in the direction opposite to that in which the same is moved in response to vacuum, this arrangement including an overcenter assembly.

Other and more specific objects, advantages and uses of my invention will become apparent from a reading of the following specification taken in connection with the accompanying drawings forming a part thereof and wherein:

Fig. 1 is a broken-away vertical section of a carburetor embodying the invention, taken generally along the axis of the main fuel and air mixing passage as indicated by the line I--l in Fig. 2;

Fig. 2 is a vertical cross-section taken substantially along the line 2-2 of Fig. 1 and showing to advantage the locking assembly as well as the overcenter assembly;

Fig. 3 is a horizontal section taken substantially along the line 3 3 of Fig. 1;

Fig. 4 is a vertical section through the distillate inlet and strainer assembly.

Fig. 5 is a broken-away vertical cross-section taken substantially along the line 5-5 of Fig. 1 and showing to advantage the respective fuel inlet valves as well as the operating cam therefor;

Fig. 6 is a vertical cross-section taken substan-` tially on the line 0-6 of Fig. 1 and showing to advantage the manually controlled linkage for adjusting the locking assembly;

Fig. 7 is a horizontal axial section taken substantially on the line 1 1 of Fig. 1 and showing to advantage both the relation of the butterfly throttle valve to the port controlling the vacuum responsive means as well as the relation of the throttle to the idle fuel supply ports:

Figs. 8, 9, and l0 are broken-away section views showing the locking assembly in successive ones of the several selective positions into which the same is arranged to be moved. Fig. 8 shows the locking assembly in the position in which the vacuum responsive piston is locked in the lowered or distillate position; Fig. 9 shows the locking assembly in the position in which the vacuum responsive piston is locked in the neutral or intermediate position wherein fuel cannot be delivered from either the distillate or the gasoline supply; while Fig. 10 shows the locking assembly in the position in which the vacuum responsive piston is locked in the raised or gasoline delivering position; and

Fig. 11 is a schematic broken-away vertical section with the essential parts shown in one plane in order to present a more composite picture of the operation in a single ligure of the drawings.

Referring in greater detail to the figures of the drawings l0 indicates generally a carburetor assembly incorporating a preferred embodiment of my invention. A main housing or body ll is formed with the usual main passage l2 therethrough having an air inlet I3 and a fuel and air outlet i4 adapted to communicate With the manifold of an internal combustion engine (not shown). The flow through main passage I2 is under the control of the usual choke valve I 6 and butterfly throttle valve il, the fuel being introduced into main passage I2 through a nozzle assembly indicated generally at i8 leading from l Aand 54a, through E9e.

a fuel bowl i9 carried on the underside of main housing il.

My invention is directed particularly to an improved arrangement indicated generally at 26 for selectively controlling the introduction into fuel bowl i9 of either a volatile gasoline or a heavy distillate fuel. This selection may be made manually or may be rendered completely automatic, 'that is, responsive to the position of throttle valve l'l which condition is selected because the same is an accurate index of the engine requirements for the respective fuels.

The selective fuel introducing assembly includes a gasoline or other volatile fuel inlet 5l adapted to communicate with a suitable supply (not shown) and a distillate or other relatively less volatile fuel inlet 52 adapted to communicate with a suitable supply (not shown). Gasoline inlet 5i communicates through strainer assembly 53 with valve chamber 54 provided with valve seat 55 against which a valve 55 is normally maintained seated by compression coil spring 5l. It will be noted that the main body portion of valve 55 is non-circular in cross-section permitting the ready flow o-f fuel therepast and to valve seat b5, conical valve portion proper 58 being arranged to engage valve seat 55 and having a coaxially extending operating pin portion 59 extending therefrom of lesser cross-sectional area than valve seat 55 and passing through said valve seat for engagement by the operating means as will appear. Valve chamber 54 is formed in a tubular member 6l externally and internally threaded for ready removal and ready replacement to facilitate cleaning and adjustment. Strainer assembly 53 includes a depending hollow housing G2 having a readily removable threaded plug S3 to permit of cleaning and containing a strainer cage 64 functioning to remove foreign particles from the fuel prior to delivery of the fuel to valve chamber 54.

Distillate inlet t2 communicates with an identical arrangement of elements designated 53a Distillate outlet port 55a communicates with a chamber ll while gasoline outlet port b communicates with a chamber 72, chamber li being in communication with chamber 'l2 through a coaxial passage 13 containing a floating reciprocable plunger 14 of non-circular cross-section permitting the ready flow of distillate from chamber Il to chamber 12, the function of which plunger will be later described. For conducting fuel from chamber 'l2 to fuel bowl i9 passage l5 delivers to valve 'il under the control of float assembly 'I8 which functions to control the level of fuel in the fuel bowl I9.

Referring now to the arrangement for selectively controlling the operation of gasoline valve 58 and distillate valve 5ta, cylinder 8| formed. in an auxiliary housing section 32 carried on the upper portion of main housing il has mounted therein for reciprocation a vacuum responsive piston S3. This piston is normally urged in the direction of the lowermost position thereof by compression coil spring il and is further arranged to be placed in communication with main air and fuel passage l2 through a vacuum control port t5. This control port communicates the pressure or vacuum existing within fuel and Vair passage i2 to the upper end of piston 83 through passage l5 in main housing Il, passage klil defined between main housing H kand auxil- 'ary housing vibration dampener'chamber 88 tillate during p-art as well as full and passage 89 leading to the upper portion of chamber 8|.

Special attention is directed to the relationship between butterfly valve ll and vacuum oontrol port 85, it being noted that this port is under the control of the peripheral portion of the butterfly valve. Referring especially to Fig 7, it will be seen that the usual two-hole idle port arrangement indicated at Sii and iia is under the control of a rst peripheral portion of butterfly valve l'i while vacuum port t5 is under the control of a second peripheral portion of this valve I'i.

It will thus be seen that when the throttle I1 approaches idle position, namely, a position in the arcuate movement thereof just prior to passing over port Sila in the closing direction, the same will then be at the point of transferring port from the low suction existing on the nozzle side of throttle valve il to the higher manifold suction being built up on the manifold side of throttle Il. The port 85 is so located that the transition from exposure to relatively low to relatively high suction is made at a position of the throttle at which the engine is normally operating at a speed slightly lower than fast idling or governed idling speed. When the port 85 is brought into the influence of high suction by the passage of the throttle periphery therebeyond in the closing direction, the resulting high depression or vacuum will be transmitted through passages 85, ii'l, vibration dampener chamber S8, and passage iii) to the upper end of piston 83 with the result that the piston is drawn upwardly against compression spring 3ds.

The raising of piston 83 by the Vacuum under the above described conditions is taken advantage of to accomplish the closing of distillate valve 55a shutting off the supply of the heavier fuel to the fuel bowl as well as accomplishing the opening of the gasoline or more volatile fuel valve 55 thus admitting the latter fuel to fuel bowl I9.

In this manner the engine supplied lll is made to operate on heavy disthrottle, while being furnished with a more volatile fuel during slow idling and up to, but not including fast or governed idling, under which condition it has been found that distillate alone will not eifect satisfactory idling of the engine.

To effect this selective operation of the gasoline valve 55 and the distillate valve 5to by piston 83, link 96 extends from the lower portion of piston 83 to which it is universally connected and terminates in a stop or end portion t? cooperating with a stop 93 formed on housing il for limiting the inward or downward movement of piston S3 by compression spring 8f3, whenever throttle valve l1 is moved in an opening direction to a suflicient arcuate extent to expose vacuum port 85 to the pressure existing on the ynozzle side of the throttle. A crank assembly indicated generally at lill includes a first end portion m2 pivoted to connector link SE at IBS adjacent the lower end by carburetor thereof, pivot w3 being a moving pivot. The

mid-portion of crank assembly lill is in the form of a yoke Itri a first arm lll of which is drivingly connected with a trunnion lill' journalled in bearing member Hill. Also carried in bearing member loll is a rotatable shaft llll having a slotted driving connection with trunnion im at one end and a driving connection at the other end thereof With a cam or crank member ill formed with a cam surfacev l l la for cooperation with actuating pin 59a of valve 5ta and formed with the' cam surface Ibffor cooperation with'the actuating cooperation with a pin |33 carried by a locking pin 59 of gasoline valve 5B. Bearing member |08 is in the form of a readily removable externally threaded hollow plug having a shoulder under the head thereof adapted to tightly engage a sealing ring for'preventing leakage therepast. Shaft |09 is formed with a conical portion ||2 for engaging the outer open end of bearing member |08 to effect a seat therewith. Extending from the outer end of shaft |09 is a coaxial pin ||3 arranged to be engaged by a spherical bearing or ball |I4 urged into engagement with lthe pin by compression spring ||6 for effectively maintaining the -sealed relationship between conica1 portion ||2 and the outer end of bearing member |08. Cam or crank member is mounted upon pin ||3 and is arranged to be reciprocated by crank arm ||1. The second yoke arm |06a has a second trunnion |01a extending therefrom and journalled in housing I I.

It will thus be seen that movement of piston 83 upwardly by the action of vacuum thereon will produce arcuate movement of crank assembly trunnion |01 and cam to move the latter into engagement with floating pin or plunger 14 which in turn engages pin 59 to move gasoline valve 56 into the open position causing the flow of gasoline into chamber 12, through passage 16 and float control valve 11, the quantity of flow being determined by float assembly 18. Reduction in the vacuum acting upon piston 83 will result in compression spring 84 effecting the lowering of piston 83 to bring the end 91 of link 98 into engagement with stop 98 turning crank assembly |0| in the opposite arcuate direction thus causing crank or cam arm to move. cam surface |||b out of engagement with trunnion 14 thus permitting the gasoline valve '56 to close under the influence of compression spring 51 and then bringing cam surface la into engagement with operating pin 59a of distillate Valve 56a opening this valve and permitting the flow of distillate into chamber 1|, and through passage 13 along non-circular plunger 14, into chamber 12,

through passage 1B and past float control valve v 'I1 into float bowl I9.

Insuring and facilitating the movement of the piston 83 and connecting links 96 in both directions beyond that position-wherein crank or lever assembly |0| is disposed with the general axis thereof at substantially a right angle to the normal axis of link 96, there is provided a special over-center spring arrangement including spring |2| one end of which is connected to a xed pivot indicated at |22 and the other end of which is connected to'pivot |03 forming the connection between link 9B and crank assembly |0|. It will A be seen that the maximum stretch in spring |2| takes place when crank assembly |0| has the general axis thereof turned substantially into a horizontal plane on either side of which position spring |2| tends to contract with the result; that there is less tendency for piston 83 to flutter and permit cam member I to assume a middle position between valves 56 and 56a.

Under certain conditions of operation it is desirable to lock valve operating assembly 26 selectively in either a distillate feeding position or a gasoline feeding position while under the condition where the motor is not operating it is equally desirable to lock the assembly against the inadvertent opening of either the distillate valve or the gasoline valve. To this end crank assembly |0| includes an extended terminal portion 3| formed with an arcuate mouth |32 arranged for cam designated generally at |34. Referring particularly to Figures 2 and 8 through 10 it will be seen that locking cam |34 may be moved to any one of four selected positions, including a first position shown in Fig. 8 wherein pin |33 is completely withdrawn from cooperation with arcuate mouth |32 thus permitting control entirely by vacuum responsive piston 83. Spring operated pawl |36 engages a detent in cam member |34 corresponding to each of the several positions for maintaining the cam in any position to which the same is moved by manual means to be described. The position of the locking cam assembly shown in Fig. 8 is the normal position of operation under conditions wherein the associated engine has been brought up to normal operating temperature and wherein there is an ample supply of both distillate and gasoline.

There are however certain conditions under which it is desirable to lock th'e Valve control assembly in a completely off-position such as illustrated in Fig. 9 wherein locking cam assembly |34 has been moved to a position where spring operated pawl |36 engages position number 2, in which position locking pin |33 is moved approximately mid-way along arcuate mouth Under such conditions cam assembly |32 to locked piston 83 in the mid position thereof wherein cam or crank member I|| is held in substantially the vertical plane and wherein the same does not engage either operating pin 59a of distillate valve 56a or plunger 14 which operates pin 59 of valve 56 In this position the compression springs 51 and 51a are effective to prevent th'e flow of either distillate or gasoline to fuel bowl I9. While assembly 26 is locked in such intermediate positions neither fuel can be inadvertently fed to the fuel bowl and any operation that may be desired in connection with the fuel bowl may be carried out, such for example as the removal of the plug |4| for the purpose of cleaning or adjusting the nozzle assembly |8.

Similarly it may be desired under certain conditions, such for example, as when starting a cold motor, to lock the Valve control assembly 25 in gasoline supply position as illustrated in Fig. l0. |34 is moved to a position where spring urged pawl member |36 is in engagement with the detent corresponding to position l, locking pin |33 being moved completely within arcuate mouth' |32 wherein it is eiective to hold crank assembly |0| in' a manner to restrain piston 83 in the lowermost position thereof irrespective of the degree of vacuum to which port may be subjected.

The above described locking arrangement may have still further advantages and application such for example as under conditions wherein one or the other of the fuel supplies has become exhausted making it desirable to prevent attempted operation on the exhausted fuel and limiting the operation to that fuel which remains.

For the purpose of manually setting locking cam assembly |34 in any one of the several positions which may be selected I employ an assembly of linkage including a rotatable shaft |5| adapted to connect with a manually operated member (not shown) which is preferably located in the cab of the Vehicle with which the carburetor is adapted to be associated. Shaft |5| operates crank |52 which in turn effects the arcuate movement of crank |53 through link |54, crank |53 being connected to shaft |56 supporting cam locking assembly |34. Thus by manually adjusting a control ymember (not shown) Alocking assembly |34 maybe readily adjusted from any selected remote point.

It has been found in the operation of this particular type of change-over carburetor that there is a tendency under certain conditions of operation lfor the piston '83 to vibrate ,or be unsteady particularly `during transition Yfrom rone fuel to another vor 2in other words, when the throttle valve if is being operated in the arca of port 85.

. In order to overcome this tendency, I have provided, in addition to the above described novel Aarrangement of Vover-center spring S2! and compression spring 213, an improved arrangement of vibration dampening discs indicated at |57 contained in chamber 83. A plurality of these discs are employed, each comprising a thin sheet metal cup-like shape provided with a depending surrounding wall portion |58 fitting snugly within the peripheral wall of chamber 88 and each having a central opening or port |56 therein through which the depression from port 85 is transmitted to the upper end of piston 83. These discs |57 cause a certain amount of resistance to the change in flow through the ports formed therein with the result that a very decided dampening action is imposed upon any tendency of the piston to oscillate or flutter.

In addition to the above described structure, there is provided the usual necessary additional carburetor elements of a well-known character not forming a particular part of the present iriventicn and not thought necessary of descriptions herein, such elements including the load adjustment assembly indicated generally at |5| and the necessary' control' linkage indicated generally at lii for operating throttle valve i'l. Rod |E2 would generally be the governor rod, the governor (not shown) in turn being manually controlled by the operator for speeds under the established governed speed.

While my invention has been disclosed in connection with certain specific embodiments there-- of, it is my intention that these be considered by way of example and not by way of limitation, my invention being defined by the appended claims which should be given a scope as broad as commensurate with the prior art.

I claim:

l. In a carburetor assembly for selectively delivering either a rst relatively volatile fuel or a second less volatile fuel, including means defining a housing having a main passage therethrough with an air inlet thereto and a fuel and air outlet therefrom adapted to communicate with the manifold of an internal combustion engine, means dening a fuel bowl and float controlled valve for maintaining a predetermined level of fuel therein, means deiining anozzleassembly for delivering fuel from said bowl to said passage intermediate of said inlet and outlet portions thereof, a butterfly throttle valve positioned in said main passage between said nozzle and ,l

said outlet for controlling thev ow therethrough, a first valve assembly adapted to control the now of said first relatively volatile fuel to said bowl, a second valve assembly adapted to control the flow of said second less volatile fuel to said bowl, said arrangement being particularly characterized by the provision of means responsive to manifold vacuum in the area of said outlet for selectively operating said rst and second valve assemblies, said means comprising a vacuum-` .responsive piston and `cam assembly, movement of said jpiston in the direction of one limit of movement Ybeing effective `to cause 'said cam to operate one of said valve assemblies while the movement of said piston in the direction of the other limit of movement thereof being effective to causesaid cam to opera-tesaid other valve assembly, `said arrangement 4including yfurther Vva `port :formed -in `said housing :in communication with said `main A:passage .adjacent :a peripheral portion of said :butterfiy valve when in or near closed fposition, means forming a passage for lcommunicating said port with said vacuum-responsive piston, whereby the Yoperation of said throttle valveto substantially closed position corresponding to idle speed of anassociated internal combustion engine results in the movement `of said peripheral portion of said throttle over said port exposing thesame to the relatively higher vacuum existing at the outlet side of said throttle to thus `effect the operation of said rst valve assembly to 4deliver saidrelatively volatile fuel -to said fuel bowl, while reverse movement of ,said 4throttlefis effective to ,expose said port to the relatively higher vpressure existing on the nozzle side of said throttle valve thus effecting thegoperation .of .said second valve assembly to deliversaid second less volatile fuel to said fuel bowl, said piston and cam assembly including a y.depending rod `or link universally connected at onefend to said-fpistonland formed at the other extremity asa stop memberfor limiting the inward movement of said piston, compression -lspringmeans for normally urging said piston in adirection tocause the engagement of said stop, a crank assembly pivotally connected to said link intermediateithe ends thereof and drivingly associated with lsaid valve lassemblx7 operating cam, theraising and loweringof said piston being effective to operate said cam through said cra-nk assembly, and a tension coil spring having laqiirst endrconnected toa fixed pivot on said `housing and the other-extremity thereof fastened `tC said pivotal connection betweensaid linkand said crank in Ja manner such that the maximum stretch of said coil spring occurs at an intermel,diate position of themovement of said piston `and link, the `extremepositions of said piston corresponding to the; minimum stretch in said spring to thus assure the movement of said piston past said intermediate position in either direction.

2.,In -a carburetorassembly for selectively deliveringeitherA a first relatively volatile fuel or a second less'volatile fuel, including means delining a housing having a mainpassage therethrough with anair inlet thereto and a fuel and air outlet therefrom adapted to communicate with the manifold of ,an internal combustion engine,

means defining la* fuel bowl and float controlled valve for maintainingY a predetermined level of fuel therein, means defining a nozzle assembly for deliveringk fuel froml saidbowl to said passage vintermediate of said inlet and outlet portions thereof, a butterfly throttle valve positioned in `said main passage `lbetween said nozzle and said youtlet for controlling the flow therethruogh, a rst valve assembly adapted to control the ow of said `first relatively volatile fuel to said bowl, a second valve-assembly, adapted to control the flow ofY said` second less volatile fuel to said bowl,

,- said varrangement being particularly characterized by the provision of means responsive to manifold `vacuum in the-,area of said outlet for selectively operating said rst .and second valve. assemblies,

said means comprising a vacuum-responsive piston and cam assembly, movement of said piston in the direction of one limit of movement being effective to cause said cam to operate one of said valve assemblies while the movement of said piston in the direction of the other limit of movement thereof being effective to cause said cam to operate said other valve assembly, said arrangement including further a port formed in said housing in communication with said main passage adjacent a peripheral portion of said butterfly valve when in or near closed position, means forming a passage for communicating said port with said vacuum-responsive piston, whereby the operation of said throttle valve to substantially closed position corresponding to idle speed of an associated internal combustion engine results in the movement of said peripheral portion of said throttle over said port exposing the same to the relatively higher vacuum existing at the outlet side of said throttle to thus effect the operation of said first valve assembly to deliver said relatively volatile fuel to said fuel bowl, while reverse movement of said throttle is effective to expose said port to the relatively higher pressure existing on the nozzle side of said throttle valve thus effecting the operating of said second valve assembly to deliver said second less volatile fuel to said fuel bowl, said piston and cam assembly comprising a link or piston rod depending from said piston having a universal connection with said piston at a first extremity thereof, the other extremity functioning as a limit of movement stop for said piston in the inward direction, a rotatable driving assembly for said cam including a trunnion having a stationary bearing in said housing, a crank assembly drivingly associated with said trunnion intermediate the ends thereof, a first end portion of said crank assembly being pivotally connected with said piston rod intermediate the ends thereof to be driven by said piston, the other end portion of said crank assembly being formed with an arcuate mouth portion, and manually adjustable locking means for cooperation with said arcuate mouth in a plurality of positions for moving said crank assembly and said piston to either of the limits of movement thereof or to an intermediate position and holding the same in such selected position.

3. In a carburetor assembly for selectively delivering either a first relatively volatile fuel or a second less volatile fuel, including means deiining a housing having a main passage therethrough with an air inlet thereto and a fuel and air outlet therefrom adapted to communicate with the manifold of an internal combustion engine, means defining a fuel bowl and float controlled valve for maintaining a predetermined level of fuel therein, means defining a nozzle assembly for delivering fuel from said bowl to said passage intermediate of said inlet and outlet portions thereof, a butterfly throttle valve positioned in said main passage between said nozzle and said outlet for controlling the flow therethrough, a first valve assembly adapted to control the flow of said first relatively volatile fuel to said bowl, a second valve assembly adapted to control the iiow of said second less volatile fuel to said bowl, said arrangement being particularly characterized by the provision of means responsive to manifold vacuum in the area of said outlet for selectively operating said first and second Valve assemblies, said lmeans comprising a vacuum-responsive piston and cam assembly, movement of said piston in the direction of one limit of movement bein-g effective to cause said cam to operate one of said valve assemblies while the movement of said piston in the direction of the other limit of movement thereof being effective to cause said cam to operate said other valve assembly, said arrangement including further a port formed in said housing in communication with said main passage adjacent a peripheral portion of said butterfly valve when in or near closed position, means forming a passage for communicating said port with said vacuum-responsive piston, whereby the operation of said throttle valve to substantially closed position corresponding to idle speed of an associated internal combustion engine results in the movement of said peripheral portion of said throttle over said port exposing the same to the relatively higher vacuum existing at the outlet side of said throttle to thus effect the operation of said rst valve assembly to deliver said relatively volatile fuel to said fuel bowl, and means for dampening the movement of said Vacuum-responsive piston, said means comprising a generally cylindrical chamber in communication at a first portion with said piston and in communication at a second portion with said vacuum control port, a plurality of superimposed cup-like discs received in said cylindrical chamber with the periperal portions thereof in engagement with the surrounding wall of said chamber, each of said discs being formed with a perforation therethrough of limited size effective to communicate the changes of vacuum to said piston, said plurality of discs functioning to dampen said changes in the vacuum effects transmitted from said port to said piston.

JOHN R. EMERSON.

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