US2131848A - Carburetor - Google Patents

Description

Oct. 4,1938. c. R. ROBIDOUX CARBURETOR Filed.June 16 1956 s Sheets-Sheet 1 Oct. 4,1938. c. R. ROBIDOUX CARBURETOR Filed June 16, 1936 3 Sheets-Sheet 2 M h P E M r W Oct. 4, 1938.

C. R. ROBIDOUX GARBURETOR 5 Sheets-Sheet 3 Filed June 16, 1936 3 11 M II M Hwm I III III I Q. 5R V4 I 6 6 2 n w a 0 l. I11 5 L \l J 2 ll v. nmfl nl n 3mm Conrad A. FoZ/a aux operate. v

Patented Oct. 4, 1938 PATIENT orrics CARBURETOR Conrad R. Robidoux, West Hartford, Qonn.

Application June 16, 1936, Serial No. 85,560 Y Claims. (01. 123-119) This inventionyrelates to improvements in carburetors of the type described and illustrated in my United States Patent No. 2,035,570 granted March 31, 1936 and is particularly concerned 1 with'such improvements as will increase the efficiency of operationand facility of control and adjustment of these carburetors.

Carburetors of the'type referred to above and disclosed in my patent are deficient in several Ways. Where :a carburetor of this character is employed of necessity means must be provided without relying upon the conventional float valve whereby the fuel passingcthrough the carburetor is positively shut off when the'engine ceases to Additionally, when carburetors of this character are made :as universal carburetors, adapted to be used on manifolds whose-throats vary in crosssectional area, compensating means must be l provided whereby the maximum volume of air admitted to the carburetor can be controlled. Further ,when metering pins or control valves of thischaracter are used they of necessity must be sealed by a diaphragm to permit their free movement to open and close the discharge orifice.

The free movement of the metering pin therefore necessitates sufiioient clearance between the metering pin and its confining walls which obviously would permit the gastoflow downwardly around the pin and accumulate to some extent in the diaphragm chamber. Therefore, when carburetors of this character are used on aeroplanes and they are' flown in inverted flight,- means must be provided for preventing fuel thus accumulated in the diaphragm chamber from flowing down the stem of 1 the metering pin and flooding the discharge orifice.

Auxiliary shut-ofi valves of the type referred to above for positively closing the passageway through which the \fuel flows in the carburetor of necessity must be operated from a remote position when manually actuated, and to reduce the number of operations necessary in starting or stopping an engine, can be combined with the ignition circuit controlmeans 7 When the auxiliary shut-off valve is made automatic in itsoperation it can be connected to the intake manifold or throat of the carburetor in vsuch a manner that the valve will :be held in open position throughout the -period when the motor is operating. i

Carburetors of this character when used with aeroplanes when flying at abnormally high altitudes operate inefliciently if no compensation is made-for the change in airfdensity, therefore as a result means must be provided whereby the operator can from his instrument board vary at will the maximum amount of fuel allowed to pass through the passageways within the carburetor.

Furthermore to insure proper atomization of 5 the fuelso that it will be readily entrained in the combustion supporting air stream, various shapes of orifices as well as valve heads or metering pin heads have been used but have not proven entirely successful and have resulted in 1Q unequal distribution of fuel from the supply orifice which causes an improper mixture in the mixing chamber.

To facilitate the adjustment of the metering pin relative to the movement of the throttle plate means must be provided which are accessible and which may be practically as well as economically assembled and adjustedr- Therefore, an object of this invention is the provision of auxiliary means whereby the fuel supplied to the metering pinor control valve may be positively shut ofi when the engine is no longer operating.

Additionally this invention has for an object the provision of means whereby the auxiliary means may be actuated without the necessity of employing a float.

This invention further contemplates actuating means for the auxiliary means which are cominon with the ignition circuit control means and may be actuated simultaneously therewith.

Another object of this invention is the provision of automatic means dependent upon the operation of the engine for shutting off the fuel passing through the passageways leading to the metering pin or control valve within the carburetor. o

Still another object of this invention is the provision of means whereby the amount of fuel passing through the carburetor can be varied from a 40 remote point to compensate for changes in the vision of additional means whereby the adjusting means associated with the mechanical linkage between the metering pin and the throttle plate is made accessible for purpose of adjustment without dismantling the carburetor.

Another object of this invention is to provide a metering pin or control valve having an axial passageway through it whereby the air drawn into the mixing chamber through the passageway will tend to keep the metering pin cool as well as aid in atomizing the fuel being discharged into the mixing chamber.

Other objects and advantages will appear from the following detailed description when considered in connection with the accompanying drawings, in which:

Fig. 1 is a vertical section of my improved carburetor showing the mechanically controlled auxiliary valve in detail;

Fig. 2 is a bottom view of the carburetor shown in Fig. 1, showing in detail the adjustable means for limiting the maximum volume of air in accordance with different size carburetor throats;

Fig. 3 is a fragmentary vertical section of a carburetor showing the auxiliary valve control means and the means whereby compensations in fuel supplied can be made in accordance with changes in air density encountered at high altitudes;

Fig. 4 is a vertical sectional view of my improved carbureter showing in detail a modified form of control for the auxiliary valve which renders the valve automatic in its operation;

Fig. 5 is a fragmentary Vertical sectional view of thecarburetor and control means taken along the line 55 of Fig. 4;

Fig. 6 is a top sectional view of the control means taken along the line 6--6 of Fig. 4;

Figs. '1, 8 and 9 are detail vertical sectional views of modified forms of metering pins or control valves;

Fig. 10 is a vertical sectional view of my improved ignition circuit control and auxiliary valve actuating means;

Fig. 11 is a cross-sectional view of the device shown in Fig. 10 taken along the line H-ll of Fig. 10; and

Fig. 12 is a fragmentary elevational view of the bottom of the carburetor shown in Fig. 3 showing the openings in the upturned flanges on the throttle and choke plates.

Referring to the drawings in detail and particularly Fig. 1, l0 refers to the substantially cylindrical casing of the carburetor. Casing I0 is brought inwardly at the top thereof to form a neck portion H which extends upwardly and terminates with the integral flange I2 that is adapted to be connected to the intake manifold of an internal combustion engine, not shown, by means of suitable bolts passing through openings l3 which register with corresponding openings in the intake manifold.

Neck ll of the casing has fixed therein by sweating or other known methods a bushing M which is so shaped that the passageway through the bushing is in the form of a Venturi passage.

Disposed within the body portion of easing i0 is a core l5 formed of aluminum, bronze, brass, iron, steel, or other suitable metals and has integrally formed therewith a plurality of radial vanes I6 adapted to fit snugly against the inner surface of the casing 10. These vanes I'B cooperate with the core l5 and the casing [0 to define a plurality of air passageways l1 through which air is conducted to a mixing chamber [8.

Mixing chamber I8 is defined by the top of core l5, which is spaced from the inwardly directed portion IQ of the casing II], and the casing I8.

Core [5 is provided with an axial bore adapted to have sweated therein a plug 20. Plug 28 is preferably formed of bronze but other tough metals suitable for bearings may be satisfactorily used.

A knife-edge valve set 2| is formed in the top of plug 20 by machining a substantially conical cavity 22 in the center of the top of the plug and then axially boring from the opposite end of the plug until the drill has reached the cavity 22. The bore 23 thus formed serves as a metering pin or control valve chamber.

Disposed within bore 23 is a metering pin 24 which cooperates with the knife-edge valve seat 2| to control the fuel discharged therethrough. The head 25 of the metering pin may be given the shape disclosed in Figs. 1 and 4 or may assume any one of the shapes shown by Figs. '1, 8 and 9.

In order to distribute the fuel evenly around the metering pin so that it will be uniformly atomized at all speeds, the upper end of the body portion of the pin is machined to a reduced diameter. With the pin thus shaped, an annular fuel chamber is formed around the pin at this point.

Metering pin 24 is provided with an axial or longitudinal passageway 26 through which air is drawn to both keep the pin cool and to aid in the atomization of the fuel being discharged into the mixing chamber 18.

Metering pin 24 is secured at its bottom end to a spring diaphragm 21 that is secured in operative position between plug 20 and a second plug 28, with suitable gaskets, by means of bolts 29.

The bottom of plug 20 is machined, as shown in Figs. 1 and 4, to form a recess or chamber 30 above the diaphragm 21. This recess is so formed thatfuel that accumulates on the diaphragm will not fiow down around the metering pin when the carburetor is used on an aeroplane in inverted flight, but will be held in the top part of the recess 30.

Plug 28 is provided with an axial internally threaded opening 3| adapted to receive an operating pin 32 that is provided with an enlarged threaded portion which is adapted to cooperate with the internal threads in plug 28. Spring diaphragm 21 tends to hold the meteringpin in its extreme lowermost position. The top of the operating pin 32 contacts the bottom end of the metering pin 24 and when rotated will be advanced by the threads to close the valve or when rotated in the opposite direction will allow the spring diaphragm to open the valve. The amount of movement of the metering pin for a given number of degrees of rotation of the operating pin can be varied by changing the pitch of the threads used.

That portion of the metering pin 24 which extends through the spring diaphragm 21 is provided with a transverse passageway 33 which will conduct the air from the chamber 34 below the diaphragm 21 into the longitudinal passageway 26 in the metering pin.

Plug 28 is provided with drilled passageways 35 which register at their outer ends with passageways 36 drilled substantially horizontally through the core l5 into the air passageways 11.

The bottom end of the metering pin extends downwardly through openings in choke and throttle plates or valves 31 and 38, respectively,

plates are provided with operating handles or ears 42 and 43, respectively. These ears extend substantially horizontally from the plates through openings in the downwardly extending flange 4|. These ears 42 and 43 are provided with openings 44 and 45, respectively,fadapted to receive operating elements 46 and 4?. The choke and throttle plates are biased toward their normal off position by springs 48 and 49, respectively.

Throttle plate 38 is connected pin 32 by means of leaf springs 50 and a spider Leaf springs 50 being provided at one end with elongated openings 52 adapted to receive screws 53, are adjustably secured to the bottom face of the throttle plate. The other end of these springs are secured by screws 54 tothe outer end of the legs of the spider 5|. Spider 5| is secured to and adapted to operate the operating pin 32. By using springs 59 to connect the throttle plate 89 to the operating pin, pressure is continuously applied to the plates tending to hold them up tight against the core l5 and shoulder :39 of casing Hi. I

Plug 29 has formed therein by boring or any other suitable method communicating passageways 54, 55 and EEK-If these passageways are made by drilling; then of necessity the bottom end of passageway 56 must be plugged as shown in Fig. 1 at 5?.

Disposed at'the point in the passageway thus formed wherepassagewayjtland passageway 55 join, is a valve. 58 of the "type described in my United. States Patent No. 2,035,570 adapted to, be set to limit the maximum amount] of fuel which may be fedthrough thepassageway.

Core i5 and casing it are provided with openings 59 and (it, respectively, by means .of which valve 58 is made accessible and a passageway through which an auxiliary valve casing 6| can be passed for engagement with a tapped opening in the plug 29. The opening in plug 29 is positioned infsuch a manner that the passageway 55 will communicate with the inside of the auxiliary valvecasingfil.

Valve casing 6| is substantially cylindrical in form and has threaded or pressed into the inner end thereof a plug 62. Plug 62 has a hole 83 bored axially through it which serves as both a valve seat for a valve head 64 and a communicating passageway between theinside of casing 6| and the passageway 56.

Valve head 94 is carried by a long valve stem 85 which extends through a guide bushing 65, in which passageways are formed then outwardly through the valve casing 64 throughpacking 65, packing nut 61, to and througha guide and bearing plate 69. The valve stem 65 is biased inwardly by a coil spring 69 which is threaded over the valve stem and bears at oneend against the guide and bearing plate 58 and at the other end against a collar l9 fixed on the valve stem.

The valve stem 65 is moved outwardly against the action of the coil spring 59 to open the valve by a bell crank ll. Bellcrank 1| is pivoted'at l2 and has formed integrally with that end which contacts collar '79, a fork which straddles the valve stem 65. The other end of the bell crank to the operating a metal strap 85 bent at a is provided with an opening 13 adapted to receive an operating element 14.

Fuel enters the interior of valve casing 6| through a projecting portion 15 of the valve casing 6|. This projection 75 has formed therein a passageway 16 which establishes communication between the interior of valve casing 6| and the fuel supply pipe or conduit Tl. Fuel conduit 1'! is screwed to the projection 75 by a conventional conduit coupling element I8.

Bearing and guide plate 88 is mounted on legs 79 by screws 89. Legs 19 are rigidly secured to the casing ID by screws 8|.

With the construction as described above, fuel flows from a supply source, not shown, into the valve casing 6| through conduit 77, passageways 56, 55 and 54 and is atomized around the head of the metering pin 25 intothe mixing chamber |8 where it is entrained by the air and passes on into the cylinders of the engine for com- 'bustion.

V To preventthe fuelfrom being completely shut off by the metering pin 24 when the throttle plate 38 is moved toward its off position by the spring 49, an adjustable stop is mounted on the flange 4| of the casing If). This stop comprises 90 angle in such a manner that when one end is welded or secured to the flange 4|, the other end will project outwardly at, an angle of 90. This end of the strap is provided with a tapped opening 86. Bolt 81 is threadedthrough the opening 86. This bolt serves as a stop against which the ear 43 will strike. After the bolt has been adjusted for the idling speed of the engine, it may be locked in this positionby a jam nut 88.

. With the mechanism described above, the auxiliary valve is manually actuated to open or close the passageway through the carburetor. To reduce the operations necessary in starting the engine the operating element 14 is connected with the ignition circuit switch so that when the valve is opened, the ignition will be turned on and when it is closed the same movement will turn off the ignition. A device by which this can be accomplished is illustrated in detail in Figs. 10 and 11 in which 89 is the dash or instru- .mounted in electrical contact therewith switch blades 98. These blades on movement of the operating handle 92 are adapted to cooperate with thefemale'contacts 99 to establish an electric circuit.- The female contacts 99 are mounted on a fiber insulating washer I09 which is secured in operative position by the bushing nut liil. To prevent the'operating handle 93 from turning, guide ribs I02 are provided on the inner surface of the cylindrical casing 9|]. These ribs are adapted to slide in peripheral openings I03 in the guide washer 94.

The operating handle 92 at its inner end, by a set screw 14, is secured to the wire of a conventional wire and tube actuating element I4. The other end of the actuating element being secured to the bell crank II which actuates the auxiliary valve.

In order to prevent the auxiliary valve from closing after having been opened to its maximum opening, a substantially U-shaped locking element I65 is secured by the nut 93 to the operating handle. Arm I06 of the U-shaped member is straight and adapted to slide freely in an opening IQ'I in the end of the casing 90. The other arm H38 of the U-shaped member is offset at I69 to form a locking element which will cooperate with an opening I II] to lock the operating handle 92 in its out position. To insure locking, the arm I66 is biased toward the other arm I06 by a spring III.

A modification of this invention is shown in Fig. 4. In this instance the auxiliary valve is made automatic in its operation. This is accomplished by making its actuation dependent upon a servomotor II2 that is connected into the throat of the carburetor by means of conduit I I3.

As shown in Fig. 4, valve casing is very similar to the structure disclosed in Fig. 1 with the exception of a lug II4 formed on the upper side of the casing that is adapted to receive a pivot screw H5. The valve head of the auxiliary valve and its valve seat are identical to those described in connection with the structure disclosed in Fig. l but the valve stem 65 differs in that it has formed on it a cam II5 adapted to cooperate with a pivoted locking lever II6. Locking lever H6 is secured by and pivots about screw H5. The outer end of valve stem 65 is connected by suitable nuts II! to a diaphragm I I8. Diaphragm I I8 is secured in operative position by screws H9 and forms with the casting I26, a chamber I2I. Disposed within the chamber I2I is a coil spring I22, one end of which is adapted to bear against the outer end of valve stem 65 or the diaphragm II8, while the other end rests against the end of elbow I23. Elbow I23 having a passageway formed therein establishes communication between the conduit II3 which communicates with the throat of the carburetor, and the chamber I2I. While the engine is running at idling speed a substantial vacuum is developed in chamber I2I and, as a result thereof, diaphragm II8 tends to move outwardly carrying with it valve stem 65 of the auxiliary valve which results in the opening of the passageway leading from the chamber Within the valve casing 6|. Movement of valve stem 65 outwardly carries the cam II5 a distance great enough that the end of the locking lever II6, which is spring-biased toward the valve stem 65, will drop in behind cam H5 and hold the valve open until the locking lever is dislodged.

Referring to Fig. 5, the operating handle of the throttle plate 43' when actuated to open the throttle causes the foot of a second operating lever I24 to be moved with it. Lever I24 is pivoted about a screw I25 mounted on the side of carburetor casing II], and is held in contact with the operating handle 43 by a conventional coil spring I26 havingone end connected to the casing and the other to the operating lever I24. Throttle plate 38 has formed on the periphery thereof a lug I2'I adapted to bear against the toe of the foot portion of lever I24 to cause the lever to be moved in the opposite direction when the throttle plate is moved to its ofi position, that is, against an adjustable stop member 81. As shown in this figure, the throttle plate is biased to its closed position by coil spring 49.

The upper end of operating lever I24 is connected by a coil spring I28 to the locking lever I I6. With such an arrangement it is evident that an opening of the throttle will place tension upon the coil spring I28 and. bias the locking lever toward the valve stem 65 of the auxiliary valve, and the locking lever, as a consequence, will on development of sufficient vacuum in chamber I2I to cause the stem to move outwardly, drop in behind the cam I I5.

As shown in Fig. 6, locking lever H6 is provided at its inner end with a lateral extension which is adapted to bear against the upper end of operating lever I24. When lever I24 is pivoted by the throttle plate being moved to its closed position, the upper end of this lever will contact the lateral extension on the inner end'of locking lever I I6 and pivot it about the screw I I6 to dislodge the locking element from behind the cam I I5 and allow the auxiliary valve to close.

The servomotor assembly I I2 is mounted on the side of the carburetor through the medium of legs I29 and screws I36.

A modification of the auxiliary valve actuating means as disclosed in Fig. 1 is shown in Fig. 3. In this embodiment of the invention means are provided whereby compensation can be made from a remote point for changes in density of the combustion supporting air, that is, by limiting the maximum amount of fuel that is permitted to pass through thecarburetor. This is accomplished by threading a collar I3I on the valve stem 65 of the auxiliary valve. Collar I3I is mounted and adapted to slide freely on guide members I32. These guide members carry stops I33 which may be in the form of collars threaded over and locked on the guides at a predetermined point by means of suitable set screws. The outer ends of the guides are secured to the guide and bearing plate 68. Connected to the outer end of valve stem 65 by means of a suitable flexible coupling is an operating element I34 that is adapted to extend to the instrument panel or dash of an automobile or aeroplane, by means of which rotation of the valve stem 65 is effected by the operator at will. Rotation of valve 65 causes a movement of collar I3I relative to the valve stem. In this manner, the collar can be positioned on the valve stem at any point desired to obtain a predetermined opening of the auxiliary valve. This structure in no way interferes with the actuation of the auxiliary valve as described in connection with Fig. 1.

In Fig. 3 there is disclosed still another modification of this invention. In this instance the throttle and choke plates are provided with upwardly extending flanges I35 and I36, respectively. These flanges are provided with openings I31 and I38, respectively, which communicate with similar openings formed in the casing ID, that in turn communicate with the air passageways II within the body of the carburetor. With this design of throttle and choke plates, the fiat or body portion of the plate proper is left blank. Extending from the upper edge of the flange on the choke plate is an operating handle or ear 42, which is connected and operated in the same manner as that described in connection with Fig. 1.

In Figs. 7, 8 and 9 areshown modified forms of metering pins which have proven successful in this type of carburetor. The metering pin, as disclosed in Fig. 7, is solid, that is, it has no central passageway but is provided at the valve end with a substantially conical tipwhich aids in the atomization and equalization of the fuel passing into the chamber. The metering pin disclosed in Fig. 8 is provided with a central passageway 26 and is provided at the valve end with a square head which cooperates with the knife edge seat to control the admission of fuel to the mixing chamber.

In Fig. 9 the metering pin is made solid but the body portion in the proximity of the head is sloped inwardly to taper the head, enough metal being left to bear against the knife edge seat to control the admission of fuel to the mixing chamber. Secured to the end of the metering pin head is a deflector I39 adapted to distribute the atomized fuel in the mixing chamber uniformly.

Although the above described is directed solely toward the construction illustrated by the drawings, I desire it understood that I reserve the privilege of resorting to all mechanical changes to which the device is susceptible, the invention being designed and limited only by the terms of the appended claims.

Having thus described my invention, I claim:

1. In combination with an air and fuel mixing device for an internal combustion engine, means for controlling the supply of combustion supporting air, means operatively connected to said means for controlling the fuel discharged from said device, said last mentioned means comprising a metering pin that cooperates with a knife edge seat to form an atomizing nozzle, said metering pin having a longitudinal passageway axially disposed therein whereby a portion of the combustion supporting air will be drawn into the carburetor through said longitudinal passageway and will effect a cooling of the atomizing nozzle.

2. In combination with an air and fuel mixing device for internal combustion engines, means for controlling the supply of combustion supporting air, means operatively connected with said means for controlling the fuel discharged from said device, auxiliary control means disposed in the fuel passageway within the carburetor adapted to be positively and manually controlled from a remote point, manually operable means for said auxiliary vcontrol means comprising in combination an operating handle operatively connected with said auxiliary control means, a pair of male contact elements carried by said operating handle and a pair of stationary female contact elements adapted to receive in contacting relationship the male contacts carried by the operating handle to effect a closing or opening of the ignition circuit when the auxiliary control means is reciprocated.

3. In combination with an air and fuel mixing device for internal combustion engines, a metering pin, means for controlling the supply of combustion supporting air, means operatively connected to said means for controlling the fuel discharged from said device, said last mentioned means being adapted to effect a movement of the metering pin, a spring diaphragm secured to said metering pin, said spring diaphragm defining with the core of said air and fuel mixing device, an annular chamber that has its maximum depth near the periphery thereof whereby fuel flowing downwardly around the metering pin will be retained said chamber when the carburetor is used on an aeroplane in inverted flight.

4. In combination with an air and fuel mixing device for an internal combustion engine, means for controlling the supply of combustion supporting air, means operatively connected to said means for controlling the fuel discharged from said device, said last mentioned means comprising a metering pin that cooperates with a knife edge seat to form an atomizing nozzle, said metering pin having a longitudinal passageway axially disposed therein, a core in said air and fuel mixing device having a plurality of passageways therein adapted to establish communication between atmospheric air and the passageway in said metering pin whereby a portion of the combustion supporting air will be drawn in to the carburetor through the passageway in said metering pin.

5. In combination with an air and fuel mixing device for internal combustion engines, means for controlling the fuel discharge from said device, choke and throttle plates adapted to limit the volume of air drawn into said carburetor, means operatively connecting said fuel discharge control means and said throttle plate comprising a spider fixed to said fuel discharge control means and adapted to rotate therewith, a plurality of leaf springs fixed to said spider and plate whereby the control and choke plates are retained in a snugly fitting relationship with the bottom of said carburetor.

CONRAD R. ROBIDOUX.

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