US2616675A - Air temperature control for carburetors - Google Patents

Description

Nov. 4, 1952 SWEENEY 2,616,675

AIR TEMPERATURE CONTROL FOR CARBURETORS Filed June 26, 1947 3 Sheets-Sheet 1 INVEN TOR. FRANK B. SWEENEY ATTORNEY Nov. 4, 1952 F. B. SWEENEY 2,616,675

AIR TEMPERATURE CONTROL FOR CARBURETORS Filed June 26, 1947 3 Sheets-Sheet 2 2% 4-: I IH 2 n:

Q g m N Q5 L INVENTOR.

FRANK B. SWEENEY A T TORNE Y Nov. 4, 1952 SWEENEY 2,616,675

AIR TEMPERATURE CONTROL FOR CARBURETORS Filed June 26, 1947 3 Sheets-Sheet 5 INVENTOR. FRA/VKB. SWEENEY ATTORNEY Patented Nov. 4, 1952 AIR TEMPERATURE CONTROL FOR CARBURETORS Frank B. Sweeney, Rochester, N. Y., assignor to Bitter Company, Inc., Rochester, N. Y., a corporation of Delaware Application June 26, 1947, Serial No 757,159

1 Cl Q aim My invention relates to an air temperature ;control for carburetors employed in gasoline engine propelled craft. lhis application is a division of my application Serial Number 630,257, filed November 23, 1945, and now Patent Number 2,574,670, issued November 13, 1951.

An object of my invention is to provide a simplified and efiicient temperature control for the air flowing to the carburetor of an internal combustion engine.

More specifically, my invention contemplates an air temperature control for the air flowing to the carburetor of an internal combustion engine wherein an air metering valve is provided in the air passage to the carburetor and air may flow through the air metering valve either from the atmosphere or through apassage open to atmosphere which is connected to a point adjacent the engine exhaust manifold, the arrangement being such that air is taken either from the connection to atmosphere or the connection adjacent to the exhaust manifold in accordance with the temperature conditions of the engine, the arrangement further being suchthat all of the air regardless of where it is taken from passes through the air metering valve so that accurate control of the air-gasolineratio supplied tothe carburetor is possible.

Other objects and advantages of my invention will be set forth more particularly in the claim and will be apparent from the following description, whentaken in connection with the accompanying drawings, in which:

Fig-. 1 is aviewpartly in section and partially diagrammaticillustrating thepressure injection carburetor of my invention;

Fig'. 2 is a side elevation of a portion of Fig. l, as" indicated by the arrows along the line of 2--2 of- Fig. 1;

Fig. 3* is a sectional view taken substantially on the line 3-3 of Fig. 1 in the direction indicatedby the arrows;

Fig; 4' is a view partly in section looking from the right of Fig. 3 and. with the cover plate of the compartment which houses the air temperature control removed;

Fig. 5 is: a side elevation of the pressure injectioncarburetor of my invention looking from the left of Fig. l; i

Fig. '6' is an enlarged sectional view of a portogether, as shown at l3.v The carburetor is connected to the intake manifold, partially indicated at M, of the engine with which the carburetor is associated. Above the mixing chamber section 12 is an air intake section 15. The particular carburetor illustrated is of the down-draft type which is the preferred form. However, this is primarily for purposes of illustrationv as the principles of my invention may be incorporated in other types of carburetors.

The carburetor is provided with the usual throttle-valve I 6, mounted. on a shaft IT, carried in bores. formed in bosses. The function and operation of a throttle valve are well known in the art to which this invention applies and no description of its function and operation is believed to be necessary. The main body section and the mixing chamber section are provided with passages which are connected to form an air flow passage. l8 through which air flows to the intake manifold of the engine under the. partial vacuum or subatmospheric pressure conditions created by the reciprocation of the pistons thereof.

The air flow passage it is normally almost closed by an air metering disc l9 which is movable from the closed position shown to a partially or fully open position, in accordance with the differential in pressure existent on opposite sides of the air metering disc. The air metering disc assumes a position dictated by the pressure conditions existent-and thus its position reflects or measures the volume of air passing through the air flow passage. While I have showna disc air metering device and believe that this has distinct advantages, other air metering devices might be employed in combination with other parts of the carburetor of my invention.

The air metering disc Hi is connected, in a manner presently described, to a fuel metering valve generally indicated by the numeral 2-]. The fuel metering valve is located in the fuel line, generally designated by the numeral 22, the fuel line being connected to a fuel pump diagram matical-ly illustrated by the numeral 23'.

The fuel pump 23 is driven in the usual manner from the engine cam shaft and is of a type in common use adapted to deliver gasoline to the fuel line at a substantially constant pressure regardless of engine operating speed. The fuel pump 23 is connected to the fuel line by a pipe 2% which extends into a threaded opening formed in the main body section of the carburetor. A bore 26-, communicating with the pipe 2 opens into a chamber '21 in which is housed. a strainer 28. Access to the chamber 27 and the strainer 23 for the purpose of cleaning the same, is gained through an opening in the main body section which is closed by a threaded cap 29.

The chamber 27 is in communication with an enlarged opening in the main body section which is adapted to receive a regulating valve assembly, generally indicated by the numeral 3 i. The regulating valve assembly 3i comprises a valve body section 32 and a cap section 33. The valve body section 32 is supported by an annular wall provided in the casting which forms the main body section II of the carburetor. Interposed between the facing surfaces of the valve body section 32 and the annular wall formed in the casting is a gasket 34 to prevent leakage of fuel as will later appear. The cap section 33 of the regulating valve assembly is threaded into the casting as shown at 35. By threading the cap section inward, pressure is applied on the gasket 34 so as to form a seal between the surfaces.

The lower end of the valve body section 32, is provided with a valve seat 3! formed at the end of a bore 38. The bore 38 constitutes a part of the fuel line 22. Extending from the bore 2 8 are one or more radial passages 39 which open into an annular recess M. The annular recess communicates with a transversely extending passage 42, one end of which is closed by a plug ii! and which also constitutes part of the fuel line 22. The transverse passage d2 connects with a vertically extending passage 43 formed in an upwardly extending part 34 (Fig. 7) which houses the fuel metering valve assembly 2!. The pressure regulating valve 3!, its function and operation are described in my above mentioned application and such description need not be repeated herein.

As shown most clearly in Fig. 6, the fuel metering valve 2i includes a frusto-conical valve element 7'3, normally adapted to engage a seat 18, formed on the end of a valve housing member 19. The valve housing member is threaded into telescopic relation with the upwardly extending part 44 of the main casting of the carburetor, as shown at 8|. The valve element H is integral with a valve stem 8E which is reciprocable in a bore 83 formed in the valve housing member is. The upper end of the valve butts against the lower end of a stem 85 connected to the air metering disc !9.

Adjacent its upper end the stem 35 is provided with a shoulder 84 upon which i seated disc elements, generally indicated by the numeral 86. The upper end of the stem is threaded to receive a nut 87, a washer 88 and a backing plate 85 lying beneath the nut and being confined thereby. The air metering disc is preferably circular and has a pair of openings or ports 9 i A fiat thermostatic spring element 9?. lies beneath the backing plate 89 and normally closes the ports 9i. However, under certain conditions of operation, as will presently appear, the thermostatic spring element 532 when heated may curl upwardly to uncover the ports 9!.

The valve housing 79 at its lower end, has an enlarged part 93 of the bore and above this is formed a cylindrical portion 9-4 of reduced diameter which constitutes a part of the metering section of the valve. Above the metering section is an enlarged portion 53 which connects with radial passages 9'! which open into recesses 98 communicating with fuel nozzles 99 and iiii. The valve stem has a cylindrical part Hi2 normally substantially in registry with the enlarged bore 93. Above the cylindrical part 582 is a tapered or other accurately formed section I03 which, when the valve ll, E8 is in a partially open position, registers with the cylindrical metering section 95.

Above the metering section of the valve stem is a part 16 of reduced diameter and above the reduced part 134 is a cylindrical section 566 which forms the abutment which is engag d by the end of the disc stem 85. The disc stem has a shoulder it? adapted to engage a shoulder 408 formed in the bore 33 to limit the upward movement of the air metering disc. A spring N39 is seated in the bottom of the passage 43 and engages the bottom of the valve stem, as shown at Hi), to urge the valve stem and the disc stem in an upward direction to close the fuel valve and the air metering disc. Since movement of the air metering disc is transmitted to the fuel metering valve element l? by the abutting relation of the stems, the fuel valve stem is substantially free floating so that the valve element i? will accurately engage its seat i8.

At the upper end of the valve housing 79, a spring H3 is coiled around the circumference of the valve housing, as shown, and its end H4 encircles and presses on the disc stem. This pressure exerted on the stem dampens the vibration of the parts.

As shown in the drawings ,even when the valve element "El is on its seat '58, a clearance exists at the metering gap between the metering section Q4 of the valve housing and the tapered metering section iii of the valve stem. However, as soon as the valve element l7 moves off its seat, the flow of fuel to the engine nozzles comes under the control of the fuel metering elements 94, E33. Downward movement of the valve stem increases the clearance between the parts and additional fuel is supplied to the nozzles, assuming constant fuel pressure. The enlarged bore 93 acts as a well beneath the metering section in which, at all times, a reservoir of fuel is maintained. When the engine is operating and the valve 7'5, '58 is partially open the well of fuel is under pressure. This arrangement insures a steady and uniform flow of fuel throughout the annular space between the metering parts 84, H33. Moreover, since there is at all times a clearance at the metering section and fuel flows through this space under pressure, there is little likelihood that the metering section will become clogged with dirt.

It will also be observed that a well of fuel exists below the fuel metering valve. When the fuel metering valve is opened slowly the displacement of fuel in the well by the valve has almost no effect insofar as increasing the fuel flow through the metering section of the valve. However, if the engine is being accelerated rapidly, the displacement of the liquid in the well causes momentarily a somewhat increased fuel flow through the metering section of the valve.

Of particular importance is the fact that the wall of the air fiow passage (Fig. 1) from the point H6 which marks the closed position of the air metering disc, slopes outwardly and downwardly as shown at i H. The outward and downward sloping shape of the wall is accurately determined so that for any part-open position of the air metering disc and the fuel metering valve, the proper ratio of fuel to air will be supplied in accordance with the speed and load at which the engine is operating. In general, the air flow passage is shaped so that the fuel to air ratio is decreased with increased air flow and heavier loads preferably until approximately full throttle position is reached.

In Figs. 2, 3 and 4, I have shown a means for controlling the. temperature of air flowing to the carburetor: the air intake section I S of the carburetor, I" have provided a. valve I'I oreferabl'y ofthe butterfly type The butterfly. valve is fixed toa shaft I-2I and the blades of the valve cn-oppositesides oftheshaf-t are of unequal wi'dfilr so that a flow' of airthrough the valve. tends tioswing the valve ina: counterclockwise direction, asviewedii'n Fig; 3', to move the valve an: openposition.

The tendency' of'the valve to: open is. resisted by a. thermostatic coiled spring I22 one end of which; as shown at: I23 is attached tothe valve and the other end of which is wound about and attached to a.-

IZ I The spring I 22 is of the Iii-metallic type so that when. it is subjected tc heat it: expands: or: uncoils. The expansion permits the butterfly valve to move toward anopen! position as dictated by: the. air flow: through the intake I 5.

biemetallic spring mounted in. a compertinent- IZ6 closed' bv a cover IZT, the-meeting surfaces of the margins of the opening and the cover I 21 being sealed by a gasket- I ZU. A pipe I28 is connectedto the carburetor, as shown at tit, and to an. air chamber [32 formed in the exhaust manifold N3, asshown at I 34. The hot gases discharged from the engine circulate throughpassageli36formed in the exhaust manifold and fresh. air is admittedto the air chamber I32 through openings" I31";

A second compartment: I138: is: formed in. the carburetor casting which is also. closed by" the cover; I2I.. The compartment I38 is filled with a suitable material I39 which may be spun glass or noncorrosive metal wool, capable of removing dust and dirt which may" enter; the pipe I29. The walls ofthe compartment I38 are pro.- vided with suitable flowpassages IIIIi through which air" is supplied to the" compartment I26. The function of the material" P39 is not only to filter" out dust and dirt particles but also to interpose, in the path of flow of air from adjacent the exhaust manifold, a resistance such that preferably when the butterfly valve is in a fully open position, no air will pass through the pipe I29.

The purposeof the above arrangement is to enable a flow of warm air to the carburetor when the engine is relatively cold and, at the same time, prevent a flow of warm air to the carburetor whenthe' engine is warm. Thus, when the thermost'atic spring I22 expands, due to the passage of warm air over it and the butterfly valve starts to open, the resistance to flow of air fromthe exhaust manifold is such that the air supplied to the carburetor through the pipe I29 is decreased. In the preferred arrangement, the flow of air to thecarburetor should cease whenthe butterfly valve is fully open.

One of the important features of the carburetor of my invention lies in the fact that all the air passing to the carburetor is metered air since all the air passes through the opening controlled by the air metering disc I9. In the conventional arrangements with which I 'am familiar, the warm air from adjacent the exhaust manifold is supplied to the intake manifold at a point below the air metering device and usually below the. 1,;throttle valve. This by-passed air is unmetered.

When the engine is initially started and is cold, "the air metering disc I9 moves to a partially open position, as dictated by the differential in pressure on opositesides. offthe disc. The air is drawn. from adjacent the exhaust-manifold which heats up very rapidly, causing in addition to an expansion. of? the thermostatic spring. I22; an. expansion of" the. thermostatic spring 92*. which. normally closes the ports. 9|. through the: air metering disc. Assuming the engine is permitted to warm. up at idling speed. the opening of the ports occurs: with the engine operating at the same. speed. Upon opening the ports 91: the. pressuresv differential on opposite sidesiof' the air metering discis increased", thereby permitting the air metering: disc. tomove to. a more nearly-- closed position to thereby cutdown the flow of fuel through the fuel" metering valve without av corresponding decrease in the flow'oi air; If the engine is operated at relatively high speed. when cold, the same effect. is. produced. the-.fuel-air ratio; being decreasedv as the engine warms up.v

It. is: contemplated, inv the preferred arrange.- ment',. that: no. air shall: be drawn from. the. exe haust: manifold when. the. engine up to. temperature and. the. butterflyvalve H9 is in its fnlly openposition; For thiE'DllI'POSB an adjustmg knob. M32 is provided. which enables. the adjustment. of? the tension at the thermostatic element. I Z2; Uporr rotating the. adjustment knob. WI in a clockwise direction, aided: by as. suitable. scale I435, the. tensionof the thermostatic spring. element: t2 2; maybe lessenedl so. that the butterfly valve reaches. a iullyopen'. position somewhat prior to. the engine. reaching its running temperature; V,

It? will be. appreciated; that if the: engine. is being" driverrin cold. weather, the. air under the hood; may be: relatively acid. This cold: air" will have an: efiect; on; the thermostatic: spring I22 contracting: it, closing: the. butterfly valve some.- what and: drawing some: warm. from. adjacent the exhanstzmanifold. If desired, the knob: M2 adjusted so-thatat allltinres some air: is drawn from. the. exhaust. manifold. or. theqlsnob may be adjusted for summer and winter driving.

' However, it will be apparent that I have provided a means for controlling the temperature of the air flowing to the carburetor.

When the engine is at its running temperature,

, assuming normal atmospheric temperature conbeneath the hood of the now warm engine. I

contemplate adjusting the theromstatic spring element so that when the engine is operated on warm days; the ports will be at least partially open without the engine being warm, as when the atmospheric temperature is high little or no additional fuel is required at starting. On extremely cold days the ports may never fully open if the temperature of the air beneath the hood does not rise sufiiciently. It will be particularly noted that all the air passing to the carburetor is metered, the opening of the ports merely decreasing the fuel-air ratio for any particular set of conditions.

pivoted to the end thereof, as shown at I 5| The link has a lost motion connection I52 to a rocker arm I53 pivoted at I54.

The rocker arm I53 carries an adjustable screw I56 which is adapted to engage a cam l5! having a lobe I53. The cam is mounted on the projecting end of the butterfly valve shaft I2I (Fig. 3). The rocker arm I53 has a tail piece I 59 which is adapted to engage a cooperating tail piece I6I formed on the cam.

When the engine is cold the parts are in the approximate position shown in Fig. 5 with the cam lobe I58 limiting the closing of the throttle since the arm EM moves in a clockwise position to close the throttle. Itwill be noted that the lost motion connection I52 is at the bottom of the slot and the engagement of the screw with the cam lobe limits clockwise movement of the arm I44 and hence the closing of the throttle.

I As the engine warms up the cam moves clockwise, as viewed in Fig. l, in'accordance with the opening of the butterfly valve. This permits the throttle to close more fully. When the engine is warmed up, the end of the screw I55 is out of engagement with the eam lobe and control of the throttle, because of the lost motion connection,

when presumably the engine is at running temperature and the butterfly valve should be open.

While I have shown the preferred form of the carburetor of my invention it will be apparent that various changes and modifications may be made therein, particularly in the form and relation of parts, without departing from the spirit of my invention as set forth in the appended claim.

Should the 2 I claim:

In a carburetor wherein an air passage is connected to a variable source of temperature of air supply and a throttle valve is located in said air passage comprising, in combination, an air metering valve movable from a position substantially to closing said passage to an open position in accordance with the pressure conditions existent in said air passage, said passage having an opening to atmosphere and an opening connected to the variable source of temperature of air supply, a valve normally closing the opening to atmosphere, a thermostatic spring element connected to said valve and to maintain said valve closed whereby the air supply for the carburetor is drawn from the variable source of temperature of air supply, said passage and the opening thereto being arranged so that the air from the variable source of temperature of air supply passes over said thermostatic spring element and all of the air from both said openings passes through the air metering valve, said air metering valve having a port, a thermostatic element normally closing said port, said thermostatic element moving toward an open position when the volume of air drawn from the variable source of temperature of air supply is reduced due to the action of said thermostatic spring element.

FRANK B. SWEENEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,502,219 Wallace July 22, 1924 1,356,238 Bracke May 3, 1932 1,968,553 Heitger July 31, 1934 2,108,556 Hardt Feb. 15, 1938 2,139,355 Coffey Dec. 6, 1938 2,325,372 Cofiey July 2'7, 1943

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