US1589175A - Carburetor - Google Patents

Description

June 15 1926. 1,589,175

A. s. HODGSON CARBURETOR Filed Nov. 16, 1925 5 Sheets-Sheet 4 A LGEQT Hovow 1, ma@ www, l Ms* lime 15 ,1926.

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UNITED STATES ALBERT SEPTIMUS HoDGsoN,

or FARNBOROUGH, ENGLAND.

CARBURETOR.

'I Application led. November 16, 1925,. Serial No. 69,484, and in Great Britain May 21, 1924.

This invention relates to; carburetors for Internal combustion engines, and the object is toprovide an improved construction of carburetor in which fthe interior of the throttle chamber is divided solas to form an expansion chamber into which the fuell is admitted,v and a diffuser chamber into which the fuel then passes and where itis mixed .with auxiliary air before passing out through aspiratingports; in which the said supply of auxiliary air is diminished as the mainsupply past the throttle is increased; in which the fuel is led to the expansion chamber through a depression chamber hav- 5 ing a controllable opening to the atmosphere;

in which the said controllable openingmay be automatically controlled so that the proportion of fuel to air may be varied automatically and maintained constant for various speeds and extent. of throttle opening; in which eddies and turbulences in the air stream through the carburetor may be eliminated; in lwhich an auxiliary supply of rich and highly 'atomized mixture may be supplied to the engine when it is desired to start from cold; and in which the connection between the carburetor casing and the fuel supply chamber shall permit' of a vertical, horizontal, or inclined disposition of the said casing.

Theninvention is illustrated in the accompanyingA drawings, in which Figure l is a vertical sectional View mainly on the line I-I of Fig. 2.

Fig. 2 is a sectional view on the line Il, II of Fig. l.

Figs. 2^ and 2B are detail views of'an automatic control device.

Figs. 3 and lare, respectively` a sidey elevation and a plan view but are drawn to a smaller scale.

Figs. 5 to 7 show the general arrangement of what is substantially the arrangement illustrated in Figs. 1, 3 and 4 but with the carburetor casing turned, relativelyto the float chamber, through90 degrees from the position shown inthe latter figures.

Fig. 5 is a plan view in section on the line V, V of Fig. 7. y

Fig. 6 is a view corresponding to 5, but. with one half of the carburetor casing, and the float chamber in plan.

Fig. 7 is a section onthe line VII, VII

* of Fig. 5. and

Fig. 8 is a section on the line VIII, VIII 0f Fig. 7..V

A is the carburetor casing near the forward end of which a bulbous choke core a1 is carried by r-ib a2, the interior of the casing 1n proximity to the core being preferably curvilinear so as to follow the contour of on the flange c2 ofthe float chamber C in `which the float c is located; the depression chamber B in turn Vcommunicates through a nozzle b1, a. passage-way b2, fuel jet D and passage-way b3 see Fig. l) with the fioat chamber supplied with fuel through a` con-- duit controlled by a oat valve. Branching off from the passageway b2 at a point between the fuel jet D and the'depression chamber` B are two passage-ways e and f* leading to devices to be described later.

The core a3 is provided with a fiange al between which andthefplane rear face of they choke core is ripped an internal flange of a fixed hollow cylindricalguide a6 concentrically arranged within the bore ofthe main carburetor casing. At the rear end of the carburetor casing (the lowermost end in the vertical arrangement) is a nxed centrally located hollow boss a7 carried by webs or ribs from the main casing.

A. control rod g1 which carries the throttle K, K', has its rear end turned so as to be a sliding fit in the bore of a sleeve a8 carried by the hollow boss a7 carried from the ring alo by the. rib a9, the lower end of the sleeve as being turned to fit the bore of the. boss a7 and having a collar which bears on the said boss al, the sleeve and boss being cut away at a point opposite the rib ai to accommodate the actuating lever e2; this rod g1 is adapted to be moved axially in anv suitable manner, preferably by a ball-headed lever g2 engaglng with a slot in the rear end of the rod; the said lever being. fixed to a transverse shaft G journalled in suitable bearings carried by the ring a fixed to the casing A, the said shaft also carrying an actuating lever g5 adapted to be operatedby the driver in any convenient manner; angular movement imparted to the shaft G imparts axlal movement to the lcontrol rod and throttle. The

sleeve a8, carried by the hollow boss al, is threaded and carries a fixed tubularfmember H which will be termed the fixed tapered member, the rear exterior configuration 71.1 of which is conical. To the 'interior of the main casing, at a point, say, a little in rear yof the centre of its length is fitted a I fixed ring a the interior surface of .which is formed by reversely set cones; this ring which provides a venturi-like constriction. of the bore of the main casing will beA termed the Venturi member.

The throttle takes the form of a casing K, K, having an inner` part K, connected. to the outer'part K, and being attached by the screw 7c3 to, and moving axially with the control rod g1; at its forward end k1 the part K is of cylindrical configuration, its

.bore sliding on and being guided and supported by the exterior of the fixed cylin.- drical guide a". The rear end k2 of the partK is of conical configuration; and cooperates .with the valve seat formed by the constricted part am of the bore of the Venturi member, closing the -said bore when thethrottle is in its extreme rearward position, (see Fig. l). Internally the said coned part/c2 of the throttle acting in cooperation withthe coned part h1 of the fixed taper member H, serves, when axial movement is imparted to the throttle, to control the admission of air tothe interior of the throttle through the open rear end thereof. A spiral spring S is fitted in the throttle which tends to move the latter rearwardly.

Through the throttle ports c* and fc5 are formed, the latter h5, at that part of the throttle which acts as a valve for the venturi constriction am, and the former 7c", in the part K.

Fuel from the duct (114 in the choke core.

enters the space g within the sleeve a and the throttle and passes through the ports la* into the part Q which will be termed the diffuser chamber. Then the throttle is partly open the movement of the air drawn, by the action of the engine suction, through the open rear end of the main casing past the venturi-like constriction` causesan aspirating actlon on the throttle ports 105;

this induces the flow of fuel through the de` pression chamber B, passage-way a4, chamber Q. and ports kt into the diffuser4 chamber Q. which under normal running conditions has been previously mixed with air, as hereinafter described; the aspirating actionalso induces the flow of air into the diffuser chamber through the end of the throttle sleeve. l

.The axial movement of the throttle by varyingthe venturi-likel opening controls the admlsson of main au: past the thrcttle and `therefore the degree of the aspirating action on the throttle ports h5 andthe said axial movement also simultaneously controls' by co-operation of the coned end vof the throttle with the tapered part h1 ofthe fixed `nember H, the admission of air tothe beingv closed by the plate 015 in which isformed the needle valve seat cB controlled by the needle valve o9. Fuel entering by o3 'passes through the ports c1", thence through the gauze 07 into the chamber cu, formed by the partition plate 015 which abuts the plate 015 and the packing washer c", from which chamber it passes through ports 012 and the seat 08 into the fuel chamber, to a height determined by the position of the fioat c; the float operating the needle valve by engaging the bulbous ends of arms c pivoted at 02, the other ends of which armsA engage the sleeves c14 fixed to the fuel valve. The cover C of the fioat chamber is held in closed position by the pivoted spring 015 as shown in Fig. 4.

The fuel from the fioat chamber after passing through the nozzle D, passes up the passage-way bzvto the depression chamber B, and can also pass through the respective branch passage-ways e1 and f1 to a priming device E, and to a fuel-ratio correcting 'device F. Fuell is admitted to the device F to fill up the tube or passageway f1 for a purpose later set forth. The priming device comprises a tube E fitting in a vertical los l bore formed in part of the float casing C.v located between 'thefioat chamber and the carburetor, the lower end e2 ofv the tube'is screw-threaded Aand fits the lower screwthreaded end of the bore so that the passageway e1 communicates with a calibrated opening e3 formed at the lower end of the tube. y

The tube E is provided with a port el which .is vpreferably tapered vcircumferentially as shown in Fig. 2, which :port aligns with the port e9 in the casingV Cgthe port 4 e9 communicates (see Fig. 5) with an annuf lar recess e14 formed in the facingfofthe main casing A; and the said recess'eu com,- municates by a passage-way e leading to av passage-way e18 formed in -the centre ofthe"v coreas, said passage-way communicating with the chamber Q through 8. calibrated. @remue e",

Within thev tube E is fitted an inner tube e, the upper end of which is open to the atmosphere, and the lower end els of which is smaller in diameter than the bore of the tube E, and iin the lower end of the.tube 618 a calibrated opening e19 is provided; the larger diameter of the tube 'e5l is provided with a longitudinal groove 62 which aligns with the port el, so that the annular space between the two tubes is put into communication with the port e9, and therefore by the described connections with the central openin e1 in the core as. t

he tube e5 fits the tube e so as to be rotatable therein' and is moved angularly 'to control the extent of port opening from the' groove e20 to the port el", andthe tube. e5 is fixed in the desired angular position lby a locatino' late 621 en a in with serr'ations in the head ofthe tube e5 and secured by' the bolt e22 (see Figs. 2 and 6).

The action of the 'priming device which may also be used for slowing running is asfollows Vhen the lnain carburetor is not in operengine, the suction above the throttle is high with the throttle closed and the suction effect acting through the passage-ways e, e, the annular recess e, the port e9 in the casl ing C, and the port @1 in the tube E', draws', by suction action, the fuel from the tube E into the carburetor casing through the passageway 616 thus providing a very rich mixture passing to the engine and this fuel sup*- ply is sutiicient to start the engine. The tube E. having been drained, the action of slow running is as follows Air passes down the tube e5 and mixing with fuel entering through the jet e3 passes up the annular space between the tubes E and e5 and the groove 62, and so to the engine through the .ports ew, e", annular groove e, passage-way e, and central passage-way Ke, the mixture being thoroughly atolnized and usually of the` correct proportion.

Should, however, the mixture be too rich for slow running, the tube e5 is moved to a small extent angularlv so that the groove e 2 is comparatively sealed off from the ports e and e9; the depression in the annular space between the tubes E and e5 is therefore reduced and less fuel is supplied to the engine. The mixture strength can therefore be adjusted for slow running conditions by the angular adjustment of the tube e5.

The opening el at the bottomof the tube ,the throttle is opened for normal-running fuel from the depression chamber B is drawn 'y through the passage-way a4 into the interior qof the throttle, ,and this puts ,the'slow runring' device outy ofy action since the main jet stream now draws air downwardly through the opening elbeca'use of the greater suction in the venturi than atport'ew.. l;

An adjustable throttle stoln (see Figs?,

and `6)"is to'regula'te the 'idling speed of the engine, thismay consist of a lug jl on .the boss J' which able screw je; l Referring nowto the fuel-ratio correcting engages with the adjustdevice F ;-the lower end of the tubeF is screw threaded' at f2 andscrews into a cor` responding tapped portion of a suitable bore 1n the casing C, fornnng a vertical ex- `tension of the passage-way f1; at the lower endy of the tube F a calibrated opening -f3 beingformed. The bore in the casing C in which the tube F .fits is enlarged so" as to form an enclosed annular space f@ round the outside of the tube F', and this space communicates through a port and passage-way f5 with the depression chamber B (see Fig.

5) the annular recess f also communicates through a port f7 with the interior of ap plug f8, rotatable in a suitable bore in the casing C about a horizontal axis by means of a lever 7' actuated by a Bowden wire device fla connected to a. casing f (see Figs.

3 to 6). The plug may be screw threaded and tit a screw-threaded bore or it may bc plain and tit a plain bore. A retaining screw f1 is employed to engage a groove in the lug.

The bore of the plug fs is provided with a lateral port fu, which by the operation of the lever ff?, may be brought more or less into alignment with the air port'. f.-2..\-j:.i1n" the casingC, the degree of' port opening being dependent upon the angular position of the plug f8, in this way the quantity of air entering the annular space f6 and from the latter through the port f5 to the depression chamber B may be controlled. f .j e

The action of the carburetor is as fob lows Assumingthe throttle K, K to be slightly raised from its seat am so as tov afford a` narrow venturi-like constriction for theair drawn through the casing A by the engine suction, the depression at the ports k will v lows, therefore, that for all normal condiv ti'onsof engine runnmgthe a1r-fuel ratio 1s pression in the cham The depression in the chamber Q is thus maintained at a suitable value and is transmit-ted through the ports 7c* to the upper part or expansion chamber Q formed in the interior of fthe throttle.. This depres' sion is thence transmitted through the bore f of the plug 'as and passage-way at to the depression-chamber B, and as the depression chamber is supplied with afregulable amount of air through the port f, the devalue than that existing in the diffuser chamber Q. The depression in the chamberA B communicates through the jet b1 and passage-way b2 with the nozzle D, thus causing va flow of fuel to be drawn through thel expansion chamber Q into the diffuser chamber Q where, before passing out through the ports 705 into the main air stream. it is thoroughly mixed with air entering between 7a2 land 71,1.

It will further be noted that fuel passing through the nozzle b1 is diffused with 'air entering the depression chamber through the port f5 and as ,the latter .air is controlled by the correcting device, the correct mixture for a predetermined position of the throttle can be determined, and when this is done I find that for any other position-of the throttle the apparatus will maintain this correct proportion.

-If now the throttle be raised to a higher position,say half its' range, the depression acting at the ports kf' will be reduced'in consequence of the reduction of the constriction-on the air stream and the reduced ve- .llocit'y Vof the latter` and for this reason the depression -in'the diffuser chamber Q would jalsotend to be reduced were it not for the factv that as the throttle rsesthe joint action.. of the part 7a2 and the partit1 results in the -closingof'th,e end opening'to the diffuser chambenQ, the-effect ofwhich increases the depression in the diffuser chamber to the extent necessary for thc correct flow of fuel to the increased air flow.

-lVhenthethrottle is raisedto the full- .open position lthe part 702. practically closes .the end opening tothe diffuser chamber, the depression then bem'g -a maximum. It fol.-

maintamed 1n correct proportion. '-1

In order to meet all the'k demands required in internal fcoi'nbustionengines under lvarious conditions. for instance when the motorv er B will be of lower y vehicle is climbing a` steep hill, and the speed is reduced by reason of excess load, when there will be a reduction of air velocity through the carburetor with a. consequent reduction of depression with fixed throttle; the flow of liquid under Variable pressure does not vary inthe same Way as the flow of air under variable pressure, and the mixture in such cases would tend' to becomeweak and the engine lrapidly loses power;

this defect is 'overcome bythe operation,

either automatically-or by hand, of the mixture correcting'device F.. j

The action of thisdevice is as follows y lVhen the carburetor is in a'slow running' position the fuel level in the float chamber rises to a height'- just below that of the nozzle b1 inthe depression chamber B, the

main jet. D is therefore submerged, andthe fuel rises in the passageway 7@ sealing the port f3 in the tube F., When the throttle is more fully opened, the depressionformed in the chamber B is such that the fuel level in the passage-way f1 and the passage-ways b2 is lowered to the level-of the orifice of the jet D; the passage-way f1 is nowl clear of fuel, and air enters through the calibrated orifice f3 and is diffused with the fuel passing from the jet D with the resulting reduction of depression at D.

As a consequence, the amount of air passing through the tube f1 is sufficient to ensure the correct amount of fuel passing when the engine is running at full throttle with normal revolutions and load. Had it not been for this correcting device: the amount of fuel would be too large for engine requirements of normal revolutions and f? actuated by a Bowden Wire or any other 'suitable transmission means under the control of the driver, 1may .be'made to .control the admission ,ofI airto the annular space 'f and thus through the port and passageway f5 to .the depression chamber B. For instance, the port f may be closed altogether, in which case the mixture would be very rich; or it maybe opened to such an'y extent as to render the depression in the chamber B negligible, and lthis may'be done when it is desired'jto apply an air-brake to theE engine of a motor vehicle descending hills, andA thereby effecting economy in fuel consump tion, under. such conditions. f

As is well known an internal combustion engine requires a richer mixture until it 'becomes hot'enough to run efiicientlyafter which the mixture of fuel and air `,can be appreciably weakened; when therefore the correcting device isnot. operated by hand.

automatic means may be employed, a suitable form of which is shown in Figs. 2^ and 2B, the construction of which is as follows The'plug f8 and its lever ff are removed, and are replaced by a threaded sleeve m1 which closes the port fn, and the boreI of which communicates with the port f7; the bore of the sleeve m1 is connected by a flexible tube m2 to the threaded end m3 of an air-control valve casing m4, in which is formed a valve seating m5; air admission through this seat being controlled by a valve p1 actuated by any suitable formI of thermo'- stat control device. In the drawings the valve p1 is actuated by a thermostat P which comprises an extensible tube p2 filled with air or other suitable medium which-is imprisoned therein; one end of the tube p2 is connected tothe thermostat casing by thel bolt p3, and the free end of the tube is connected by a rod p4 to the Valve p1. The casing m4 can be initially adjusted relatively to the valve p1 by screwing it on or od the screwed end of ma and it is fixed in position by means of the nut m".

The thermostat is located in respect to the engine, say in the crank casing, so that the temperature of the fluid in the thermostat is supplied through the port f5 to the depression chamber B; the mixture suppliedto the engine is therefore rich enough to ensure easy starting.

As theengine temperature rises, heat is communicated to the extensible tube p2, whereupon the tube p2 extends and opensthe valve admitting air through the valve seating m5, flexible tube mi., port f7 and port f5 to the depression chamber B, 'the effect of which is to gradually weaken the mixture until when the engine is sufficiently hot it is operated efficiently by a suitable mixture.

The setting of the valve p1 is such as to supply the right amount of air to the depression chamber B to ensure the correct air-petrol ratio, and this adds to the economy7 and 'efficient running of the engine.

The maximum opening of the valve p1 is limited in any convenient manner, say by an adjustable screwed plug p5 engaging with the collar p, so that should the engine become unduly hot the mixture strength is not i abnormally affected.

While I refer to the substitution of the sleeve m1 for the plug f8, obviously the plug and the sleeve may be located in different seatingsl arranged to communicate with l A The arrangement 1 described is found .to give excellent results', but the details of construction may of course be modified according to the size and duty of the carburetor.

Having now fully described my invention, I decla-re that what I claim and desire to secure by Letters Patent is l. In a carburetor, in combination, a main casing having a bore one end of which forms the carburetor outlet, and the other end of which opens to the atmosphere, a constriction in said bore, a hollow throttle axially movable in said bore and controlling the air flow through the annulus between the throt tle and the said constriction, a fixed main fuel conduit connected to the fuel supply, 'a fixed cylindrical sleeve at the forward end of the throttle and into the interior of which the fixed conduit opens and with which the forward end ofthe throttle makes a slidingjoint, aspirating ports in the wall of the throttle the extent of opening of which is regulated by axial movement of the throttle, a perforated partition dividing the interior of -the throttle'into two chambers, one an expansion chamber into which the main fuel conduit leads and the other a diffuser chamber, means for controlling the admission of air through the rear 'end of the throttle which reduce the area for the admission of saidair as the throttle is opened, and means for axially moving the throttle.

2. In a carburetor, in combination, -a main casing having a bore one end of which forms the carburetor outlet, and the other end of which 'opens to the atmosphere, a constriction in said bore, a hollow throttle axially movable in said bore and controlling the air flow through the annulus between the throttle and the said constriction, a fixed main fuel conduit connected to the fuel supply, a

fixed cylindricalr sleeve at the forward end l of the throttle and into the interior of which the fixed conduit opens andwith which the forward end of the-throttlemakes a sliding joint, aspirating ports in thewall of the throttle the extent of opening of which is regulated by axial movement of the throttle, a fixed bulbous choke core located in the main bore of the carburetor casing, in which theI main fuel conduit is located and by which the cylindrical sleeve isv carried, andmeans for reducing the admlssion of rair through the rear end of thethrottle as said throttle opens, substantially as described,

3. In 'a carburetor, in combination, a main casing having a bore one end of which forms the ycarburetor outlet, and the other end of which opens to the atmosphere, a constriction in said bore, a hollow throttle axially movable in said bore and controlling the air iiow through the annulus between the throttle and the said constriction, a fixed main fuel conduit connected to the fuel supply, a fixed cylindrical sleeve at the forward end of the throttle and into the interior of which the fixed conduit opens and with which the forward end of the throttle makes a sliding joint, aspirating ports in the wall of the throttle the extent of opening of which is regulated by axial movement of the throttle, starting' means comprising an auxiliary conduit connected with the fuel supply andthe throttle which reduce the area for thev admission of said air as the throttle is opened, and means for axially moving the throttle.

4. In a carburetor, in combination, a main casing having a bore one end of which forms the carburetor outlet, and the other end of which opens to the atmosphere,` a constriction in said bore, a hollow throttle axially movable in said bore aiid controlling the air ow through the annulus between the throttle and the. said constriction, a fixed main fuel conduit connected to the fuel supply, a xed cylindrical sleeve at the vforward end of the throttle and into the interior of which the fixed conduit opens and with which the forward end of the throttle makes a sliding joint, aspirating ports in the wall of the throttle the extent of opening of which is regulated by axial movement of the throttle, starting means comprising an auxiliary conduit having its outlet end at the outlet end of the bore of the main casing, a calibrated opening connecting said auxiliary conduit with the main fuel conduit, a tube having an elongated port communicating with the auxiliary conduit and having also an opening communicating with the fuel supply, a second tube rotatably mounted in the first tube and having its interior open to atmosphere, said rotating ltube having an opening communicating its interior with thel space between the tubes, said inner tube having a groove on its exterior connecting said the carburetor outlet, and the other end of f which opens to the atmosphere, a constriction .in said bore, a hollow throttle axially movable in said bore and controlling the air flow through the annulus between the throttle and the said constriction, a fixed main fuel conduit connected to the fuel supply, a fixed cylindrical sleeve at the forward end of the throttle and into the interior of which the fixed conduit opens and with which the forward end of the throttle makes a sliding joint, aspirating ports in the wall of the throttle the extent of opening of which is regulated by axial movement of the throttle, means for controlling the supply of air to the rear end of the throttle comprising a turned in lower end of the throttle and a ixedconed part cooperating therewith, the forward end of said coned part being of larger diameter than the rear end and means for operating vthe throttle. i

6. In a carburetor in combination a main casing having a bore, one end of which forms a carburetor outlet, an atmosphere port, a fixed main fuel conduit connected to a fuel supply, al depression chamber connected to the main fuel conduit, av fuel nozzle inthe said chamber, a submerged jet connected to the fuel supply,.a conduit between said jet and said nozzle, a regulable opening for the admission of air to 'said chamber, a' vertical tube the upper end ofwhich is open to the atmosphere, a calibrated opening in the lower endv of said tube, and a conduit connecting the said calibrated opening to the conduit connectingthe submerged jet to the nozzle in the depression chamber.

7 In a carburetor', in combination, a main casing, an axially movable throttle, a perforated diaphragm in the throttle dividing it into an expansion chamber and a diffuser chamber, a depression chamber connected to the expansion chamber, a nozzle in the depression chamber connected to the fuel supply, a regulable air inlet. to the depression chamber, aspirating ports in the diffuser chamber, the extent of opening of which is controlled by movement --of the throttle, means for controlling the supply of air to the diffuser chamber in accordance with the extent of opening of the throttle, and means for moving the. throttle.

In witness whereof I have hereuntoy set my hand.

r ALBERT S. HODGSON.

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