US2245672A

US2245672A - Carburetor

Info

Publication number: US2245672A
Application number: US744329A
Authority: US
Inventors: Scott F Hunt
Original assignee: BENDIX PROD CORP
Current assignee: BENDIX PROD CORP; BENDIX PRODUCTS Corp
Priority date: 1934-09-17
Filing date: 1934-09-17
Publication date: 1941-06-17
Anticipated expiration: 1958-06-17

Description

. June 17, 1941. s. F. HUNT 2,245,672

GARBURETOR y Filed Sept. 17, 1934 2 Sheets-Shet 1 Z 5g 42\g llljs 45g l 41ow /4 0 1 47 E! r 171g/ "4: if 4" 6 Y f 48 Engg., i

54 lxl 1' /4 26 KSULWr/O/'Y Z 6^ v JNVENTOR.

June 17, 1941. 5 HUNT 2,245,672

CARBURETOR 'Filed sept.l 17, 1954l 2 sheets-sheet 2 im? E l C: CUIT 59;

INVENTOR. 66071 F HUNT ATTORNEY.

`Parental June 11, 1941 2,245,672 caminamos Scott F. Hunt, South Bend, Intl," assignor to Bendix Products Corporation, South Bend, Ind., a corporation of Indiana Application September 17, 1934, Serial No. 744,329

2z claims.

This invention relatesfto carburetors, and more particularly to means for controlling the choke valve of carburetors, so as to furnish the most economical and efficient combustible mixture to the engine.

'The richness of the mixture supplied by the I carburetor is usually controlled by varying the quantity of air admitted to the carburetor, by means of a choke valve which operates to vary the effective area of the air inlet passage.

It is desirable to control the choke valve auto= matically, in such a manner that the carburetor will supply a rich mixture when the engine is co1d,'and a progressively leaner mixture as the engine warms up to normal operating temperature.

This invention is an improvement upon the device disclosed in Patent 2,071,633, issued February-23, 1937, to the present applicant, and in its preferred form covers an automatic choke mechanism constituting an improvement on that dis-L closed in Patent No. 1,945,191, issued January 30, 1934, to the present applicant. The device hereinafter disclosed includes a carburetor having an unbalanced choke valve, urged toward its open position by the force of the air entering'l the air inlet passage and impinging on the unequal areas of the valve on either side of the choke shaft. The force of gravity acting on the unbalanced choke valve also tends to open the valve.

The choke valve is yieldingly urged toward the closed position-by a thermostatic element which exerts on the choke valve a force which is dependent upon the temperature of the thermostat. When the engine begins to operate under its own power, an electric current is passed through a resistance coil, placed in juxtaposition to the thermostat. The thermostat becomes heated by the coil and exerts a decreasing force urging the choke valve toward closed position.

The resistance'coil placed in juxtaposition to 'the thermostat is controlled by the engine ignition la compact and serviceable unit of the class deseveral views:

scribed, which will be less susceptible to maladjustment and failure in service, and economical to manufacture.

Other objects and advantages of the invention will beapparent from the following description. taken in connection with the accompanying drawings, submitted for purposes of illustration only,

- and not intended to denne the scope of the invention, reference being had for that purpose to the subi oined claims.

In the drawings, wherein similar reference nu-4 merals refer to similar parts throughout the.

Figure 1 is a longitudinal view, partly in section of a carburetor equipped with a device of the present invention;

Figure Z is a view taken on the line 2-2 of- Figure 1, looking in the direction of the arrows: Figure 3 is a view taken on the line 3-3 of Figure 1, looking in the direction of the arrows;

Figure 4 is a diagrammatic view showing the electric circuits of the device;

Figure 5 is a view, partly in section, showing one type of automatic switch operating mecha-` nism;

Figure 6 is a sectional view of a modified form of switch operating mechanism wherein engine` exhaust pressure is employed to close the circuit;

Figure 7 is a sectional view of a further modication, showing a thermostatically operated switch; v

Figure 8 is a sectional view of a further modification wherein manifold vacuum is employed to actuate an electric switch; and

switch, and by a switch automatically closed only during engine operation. I A

An object of this invention', is, therefore, to

provide an improved means for controlling the4 choke valve of a carburetor in accordance with vide electric means for heating the thermostat operable only upon engine starting. Y,

' Another object of the invention is to provide Figure' 9 is a diagrammatic view of a further `modification disclosing an electrically operated relay. e

Referring more particularly to Figure 1, there is shown for purposes of illustration, a downdraft.

plain tube carburetor, having an air inlet passage Iii communicating with a main carbureting passage i2. The air inlet passage Il is adiustablyl controlled by an unbalanced choke valve Il, fixed to a choke shaft Il. The choke valve il is provided with a spring pressed poppet relief valve it, to permit a small amount of air to bypass the choke valve under certain operating condi- -I tions.

The main carbureting passage I2 is tted with a secondary venturi 2t, into the most restricted section of which a primary venturi 22 discharges. 'I'he primary venturi is supported by a iin (not shown) extending from the walls of the main carbureting passage. A main fuel discharge nozzle 24 is positioned in the most restricted section fuel discharged from the fuel nozzle 24, and the air entering the air inlet passage I0, is controlled by a throttle valve 26, xed toa throttle shaft lll. When the throttle valve 28 is closed, fuel for idling purposes is furnished from the fuel reservoir 26, by a duct 32 terminating in an idling nozzle 54, posterior to 'the throttle valve 26. Air for idling purposes is supplied through a passage I6, anterior to the throttle valve 26, and communicating with the passage 34. An idling adjustment screw 38 is provided, by which the quantity of combustible mixture bypassing the throttle valve 26 may be adjustably controlled.

The choke valve I4 is actuated in the closing direction by a thermostatic element 40, housed within a chamber 42, formedby a flat plate 44 and a metal casing 46. The chamber 42 may be heat-insulated in any suitable manner, if -desired. The choke shaft I6 projects through the plate 44 and is fixed to the inner end of a spiral thermostat 40 in such a manner as to be insulated therefrom, as shown, and actuated thereby. The metal casing 46 is provided with an insulated terminal 48, to receive one end of an electric wire 61. An electric resistance coil 52 is xed on the inside of the casing 46 in heat exchange relation to the thermostat 46 and is separated from the casing 46 by an insulating member 41. A snap contact member 54 is connected with one end of the resistance coil 52, and bears against the inner end of the thermostat 45 in electrical conducting relation. The outer end ofthe thermostat 4|! is formed in the shape of a hook, to engage a stop member 56, fixed in the plate 44 so as to form an electrical connection or ground circuit therewith. f

As described hereinafter, the thermostat 46 is heated electrically when the engine begins to operate on its own power, and the circuit is broken when the thermostat -becomes heated and uncolls, thereby moving the hooked end outof contact with the stop member 56, to break the electric circuit through the resistance coil 52.

Figure 4 illustrates the relation of the electric f circuits ofthe device to those of an internal combustion engine. Electric current is supplied by a storage battery represented at 58. through the wires 60, 6| and 62 when an ignition switch 63,

but when the speed of the engine increases, an engine-operated generator 66 supplies the current. The generated current is passed through a lead '65 to a solenoid 16 comprising a resistance coil 1I wound upon a core 12. When the voltage of the generated current is greater than that supplied by the battery 56, the solenoid 1l will become energized and draw an arm 1I toward the core 12, whereupon a movable contact point is m'oved into engagement with a fixed contact point 111, in the known manner. The generator 68 then furnishes the current for. the igniinterposed in the wire 6|, is closed, to the ignition circuit 59. When the ignition switch 63 is closed and the engine is started, an engine-operated auxiliary switch, having a movable contact member 64, and a xed contact member 65, is closed by automatic switch operating mechanism 66 described hereinafter, whereupon an electric current flows through the wire 61 to the resistance coil 5 2, to heat the chamber 42 and the/thermostat 40. As the thermostat 46 becomes heated, it will tend to uncoil, thereby exerting a decreasing force tending to close the choke valve I4, and finally uncoiling to such an extent that I the hooked end disengages the stop member 56,

thereby breaking the electric circuit and discontinuing the flow of current through the resistance coil 52.

When the engine is operating below a predetermined speed, the current passing through the resistance coil 52 is supplied by the battery 56,

tion circuit and the resistance coil 52, through a wire 16 connected to the fixed contact point 11 and the wire 6I. Any excess current supplied by the generator 68 is passed through the battery 56 as a charging current inv the usual manner. When the voltage of the generated current is less than that supplied by the battery 56, as when the engine is stopped, the solenoid 16 becomes deenergized, whereupon a spring 51 moves the arm 'I3 to -the rightlas viewed in Figure 4, to move the contact point 15 away from the xed contact 11 to interrupt the current flowing from y the generator 66.

Since it is desirable that the hea-ting of the thermostat be effected proportionately to the heating of the engine, the flow of current through the resistance coil -52 is started only when lthe engine is actually running, and not merely when f the ignition switch is turned on. If the heating of the resistance coil began immediately upon turning the ignition switch, the thermostat 46 might permit the choke valve I4 to open before the engine had started, if it failed-to start promptly, or if the operator failed to actuate the starting mechanism (not shown) promptly upon turning the ignition switch.

To obviate this diiliculty the present invention incorporates an auxiliary switch having movable and fixed

contact members

64 and 65 respectively,A operable automatically upon engine starting, by a switch operating mechanism 66.

Figure 5 illustrates one type of switch operating mechanism 66 wherein oil pressure developed by a conventional oil pump represented at 14, is i employed to actuate a piston 16, in a cylinder 16, to move a lever 66 operably connected to the piston 16 by a rod 62. The lever 66 carries the mov able contact point 64, which engages the 'fixed contact point 65 when the piston 16 is actuated, thereby closing an electric circuit through the resistance coil 52. When the oil pressure drops below a predetermined value, as when the engine is stopped. a spring 66 returns the/piston 16 to its inoperative position, wherein the contact points 64 and 65 are separated.

Figure 6 shows an arrangement wherein exhaust pressure is employed to close the heating circuit.y An unbalanced valve /96 is mounted in the exhaust pipe 92. When'the engine is operating, the pressure of the exhaust gases rotates the valve 96 in the counterclockwise direction, thereby rotating an arm 94, fixed thereto, to exert tension on a link 66, operably connected to `a crank to move the contact points 64 and 65 position started, the thermostatic elementl |04, subjected to the heat of the exhaust gases, becomes deformed, and moves to the position indicated in dotted lines, whereby the movable contact. member 64 engages the fixed contact member 65 to close the circuit through the resistance coil 52 of Figure 4. When the engine has stopped and cools down, the thermostatic element IM returns to its original position to yseparate the contact points 64 and 65 to break the circuit through the resistance coil 52.

Figure8 illustrates an embodiment wherein the vacuum developed in the engine manifold IH is applied through a pipe H to lone end of a cylinder II2. When the engine is operating, the pumping action of the engine (not shown), is exerted in the cylinder H2 to move a piston IM to the left, thereby compressing a spring H6. The piston rod IIB and the connection |20 move the contact point 64 into engagement with the contact point 65 `to close the circuit and heat the thermostat 40. When the engine is stopped, the spring H6 moves the contact point 64 away from the fixed point 65 to break the circuit through the resistance coil 52.

The embodiment shown 'in Figure 9 is similar in many respects to that shown in Figure 4, and corresponding parts have therefore been given corresponding reference numerals. When the voltage generated by the generator 68 is higher than that supplied by the battery 58, the solenoid 10 will become energized, thereby drawing the arm 13 in contact with the core 12 of the solenoid, and also moving the contact point 64 .into engagement with the fixed contact point 65 to close the circuit through the resistance coil.52. When the generated voltage drops, as when the engine is stopped, the spring 51 moves the arm 'I3 out of contact with the core 12 of the solenoid 10, and moves they contact point 64 away from the fixed contact65 to break the heating circuit through the coil 52.

The invention thus comprehends a device in which an unbalanced choke valve is urged toward the closed position by a thermostat when cold, and heating means Ioperate only when the engine has started running and the thermostat is exerting'a 'force on the choke valve, to gradually decrease and nally to eliminate the force of the thermostat on the choke valve. The choke valve will then be moved to the full open by the combined force of gravity acting on the unbalanced valve, and the force of the air entering the air inlet passage I0. As long as the engine continues to run, the'choke valve will remain in the full open position. When the engine is stopped and cools ofi, the thermostatwilllmcoil until the,hooked end of the thermostat engages the stop member 56, whereupon it will exert a force on the choke valve, urging it toward the closed position. No current will flow through the resistance coil 52, however, until the rengine is started.

Although the invention has been described with particular reference tol the embodiments shown in the drawings, it is to be understood that itP may bel embodied lin other forms and is not .limited except by the terms ofthe following claims. i

I claim: "1. InA aT carburetor for an internal combustion engine having an electric ignition system -lncluding a generator to supply electric current,

a main induction `passage inthe carburetonan. unbalanced choke valve pivotallymounted inA the induction passage, thermostatic means urging the choke valve closed when cold, and electric heating means adapted to heat the thermostat to decrease the force of said thermostat `when the engine is started and electric current is supplied 'by the generator.

. 2. In al carburetor for an internal combustion engine having anignition circuit, means for control-ling the inflow of air to the carburetor, temperature responsive means for actuating said controlling means, and electric means in said ignition circuit operable only when the engine is operating for varying the force of said temperature responsive means.

3. In a carburetor having an air inlet passage, a choke valve controlling the ilow of air into said passage, temperature responsive means controlling the choke valve when cold, electric means for controlling the action of the temperature responsive means, said electric means being operative only after the engine has been started, and

substantial reduction in pressure in the main carbureting passage posterior to said throttle valve.

5. In a carburetor having a main carbureting passage, an unbalanced choke valve, a throttle valve, a thermostat urging the choke valve closed when cold, electric means operable to control the action of the thermostat only upon a substantial reduction in pressure in the main carbureting passage posterior to said throttle valve, vand means to interrupt the action of the `electric means when the thermostat ceases to urge the choke valve closed.

6. In a carburetor for an internal combustion engine having an electric ignition system, an ignition switch, an oil pump, an oil pressure actuated motor, an electric switch operable by said motor,a main induction passage in the carburetor, an unbalanced choke valve in the induction passage, temperature responsive means urging the choke valve closed when cold, and electric means to control the action of the temperature responsive means, said electric means becoming operable upon closing both the ignition switch and the oil pressure operatedelectric switch.

7. In a carburetor for an internal combustion engine having an electricv ignition `system, an ignition switch, an oil pump, an oil pressure actuated motor, an electric switch operable by said motor, a main induction passage in the carburetor, an unbalanced choke valve-in the induction passage, temperature responsive means urging the choke `valve closed when cold, electric means to modify the action of the temperature responsive means, said electric means becoming operable `upon closing bothp the ignition switch and the oiL pressure operated electric,v y

switch, and means to interrupt the action of the electric means when the temperature responsive means ceases to urge the choke valve closed.

' 8. In a carburetor for an internal combustion engine having an electric ignition system, an

ignition switch, an intake manifold constituting a source of vacuum when the yengine is running, an electric switch, a vacuum vactuated motor adapted to close lsaidswitch when the vacuum in the intake manifold reaches a predetermined value, a main .carbureting passage, an unbalanced choke valve mounted in the carbureting passage, temperature `responsive a main carbureting passage, an unbalanced choke valve mounted in the carbureting passage, temperature responsive means urging the. choke valve closed when cold electric means to control the action of the temperature responsive means, said electric means becoming operable upon closingboth the ignition switch and the vacuum motor actuated electric switch, and `means to interrupt the action of the electric means when the temperature responsive means ceases lto urge the choke valve closed.

10. In a carburetor for an internal combustion engine having an electric ignition system, an ignition switch, a generator, a generator operatedl electric switch, a main carbureting passage, anunbalanced chokevalve mounted in the carbureting passage, temperature responsive means urging the. choke valve closed when cold, and electric means to modify the action of the temperature responsive means, said electric means becoming operable upon closing both the ignition switch andv the generator operated electric switch. ll. In a carburetor for engine having an electric ignition system, an ignition switch, a generator, a generator operated electric switch, a main carbureting passage, an unbalanced choke valve mounted in the carbureting passage, temperature responsive means urging, the choke valve closed when cold, electric heating means controlling the action of the temperature responsive means, said heating means becoming operable upon closing both the ignition switch` and generator operated electric switch, and means to interrupt the action of the heating means when the temperature responsive means ceases to urge the choke valve closed.

12. In a carbln'etor for an internal combustion engine having an electric ignition circuit,

an igition switch, an electric switch, means operative only during engine operation for closing said switch, a main induction passage in the carburetor, an unbalanced choke valve in the induction passage, temperature responsive means urging the choke valve closed. when cold, elec#- t'ric means to modify the action of the tempera.'- ture responsive means, said electric meansbecoming operable upon closing the ignition switch. and the closing of the first mentioned switch.

13. In a carburetor for an internal combustion engine having anelectric ignition circuit, an igition switch, and an electric switch `means operlative only -during engine'operation for closing said switch, a main induction passage in the carburetor, an unbalanced choke valve in the inducf tion passage. temperature responsive means urging the choke valve closed when cold', electric means to modify the action .of the temperature an .internal combustion responsive means, said electric means becoming operable upon closing of both the ignition switch and the ilrst mentioned switch, and means to interrupt the action of the electric means when the temperature responsive means ceases to urge the choke valve closed. I

14. In a carburetor for an internal combustion engine having a source of pressurewhen the engine is running, an induction passage, achoke valve controlling the flow of air into the induction passage, thermostatic meanscontrolling the choke valve, a casing sun'ounding the thermostat, electric heating means inthe casing adapted' to heat the thermostat under certain operating conditions, and'switch means operable by said source of pressure to initiate a ilow of electricity through the heating means when the engine is started,

15. In a carburetor for an internal vconfxbustion engine having an ignition circuit including a generator' adapted to supply'electric current, a main vinduction passage, an unbalanced choke valve adapted to control the ilow of fluid into the induction passage, a thermostat adapted to urge the choke valve toward the closed position at low temperature, a casing surrounding the thermo- A stat, an'el'ectric heating coil in the casing, a

stop member in the casing adapted to receive one end oi' the thermostat, insulating means between the stop member and the thermostat, insulating means between the thermostat 'and the choke valve, and means including a switch adapted to initiate a ilow of current to the heating coil when the engine has started and a predetermined flow 'of current is supplied by the generator.

16. In a carburetor for an internal combustionv engine having an ignition circuit including a generator adapted to supply electric current, a main induction passage, an unbalanced choke valve adapted to control the flow of fluid into the induction passage, a thermostat adapted to urge the choke valve toward the closed vposition at low temperature. a casing surrounding the thermo stat, an electric heating coil in the casing, a stop member in the casing adapted tno receive one end of the thermostat, insulating means between the stop member and the thermostat, insulating means between the thermostat and the choke valve, and means including a switch adapted to initiate' a iiow of current to the heating coil when the engine has started and a predetermined flow of current lis supplied by the generator, and means to interrupt the flow of current to the heating coil when` the thermostat ceases to con- .trol the choke valve.

17. In a carburetor for an engine having means l .to supply pressure to av uid when the engine valve to the closed position at low temperatures,

a casing surrounding the thermostat, electric heating means in the casing adapted to heat the thermostat, switch operating means adapted to supply electric'current to the heating means upon the existance of a predetermined pressure in the pressure source, and insulating means to interrupt the flow of electric current to the heating means when the thermostat ceases to control the choke valve.

18. In a carburetor having an inductionpassage, a choke valve controlling the inilow ofi air to said passage, temperature responsive means influencing the movements of the choke valve,

heating means becoming operative only when the engine is operating, and becoming inoperative when the temperature responsive means reaches a predetermined temperature. ,l

19. A choke mechanism -for the charge forming device of an internal combustion engine having in combination means for varying the fuel to air ratio in the mixture formed by said charge forming device comprising a choke valve for closing the air intake of saidcharge forming device, thermally` responsive means for operating said valve, means other than the'engine but.

rendered operative when the engine` begins to run under its own power for heating the thermaily responsive means, and means for renderingsaid last named means inoperative.

20. A choke mechanism for the charge forming device of an internal combustion engine having in combination means `for varying the fuel to air ratio in the mixture formed by said charge forming device, thermally responsive means for operating said ratio varying means, means other than the engine but rendered operative when the engine begins to run under its own power for heating the thermally responsivev means, and means operable by the thermally responsive means for rendering the heating means inoperative. l.

21. A choke mechanism for the charge forming device of an internal combustion engine having in combination means for varying the fuel to air ratio in .the mixture formed by said charge forming device, thermally responsive means for operating said ratio ying means, relatively remotely located wit respect to the engine. heating means for raising the temperature adjacent the thermally responsive means more rapidly than the temperature adjacent the ensine is raised and means operable by the thermally responsive means itself for rendering the heating means inoperative after a predetermined eft'ect on said thermally responsive means.

22. A choke mechanism for the charge forming device of an internal combustion engine having in combination means for varying the fuel to air ratio inlthe mixture formed by said charge forming device, a thermostat for operating said ratio varying means, an electric heating device ing device inoperative.

for heating the thermostat, a generator, means operable by the generator for causing said heating device to become operative; and means operable by the thermostat for rendering the heat-