US3269713A

US3269713A - Carburetor having an idle governor

Info

Publication number: US3269713A
Application number: US433261A
Authority: US
Inventors: Niels J Beck
Original assignee: Mcculloch Corp
Current assignee: Mcculloch Corp
Priority date: 1965-02-15
Filing date: 1965-02-15
Publication date: 1966-08-30
Anticipated expiration: 1983-08-30

Description

Aug. 30.1966 l j im. BfEfcK l 3,269,713

l clu'vnron luvxxfm AN vInma Gbvnnuon Filed Feb.' 15, 1965 2 shuts-shan '1 a! 7 so a 74 Tlf fg. n'

4 a 54 mi y INVENTOR. :a man a mmm/@AL Aug. 3u, 1966 N. J. @gen 3,269,713

CARBURETOR HAVING AN IDLE GOVERNOR Filed Feb. 15, 1965 2 sheets-sret a 3,269,7i3 Patented August 30, 1966,v

n Filed Feb. l5, 1965, Ser. No. 433,261

' 4 Claims. (Cl. 2614l) This invention relates generally to governors for internal combustion engines, and relates more .particularly to governors of the suction type.

While the invention has particular utility in connection with internal combustion engines, and is shown and described in such connection, it is to be understood that Iits utility is not confined thereto.

The problem of providing a suitable and effective governor for internal combustion engines involves certain difficulties. For example, where the suction or velocity type of governor isused in addition to the usual throttle valve of the engine, difficulty in starting the engine m-ay be'encountered due to the fact that thethrottle valve Ais in the substantially closed or idle position, even though the governor valve is open.

It is therefore an object of the invention to solve the problem vand overcome the difficulties involved therein.

It is another object of the invention to provide an arrangement wherein the throttle valve of the carburetor also functions as the governor valve.

It is still another object of the invention to provide mechanism of this character with which starting of the engine is facilitated and rendered easier than heretofore.

It is another object of the invention to provide mechanism of this character that is extremely simple in construction and operation.

lt is a still further object of the invention to provide mechanism of this character having simple adjustment means whereby any desired idle speed may be provided.

It is another object of the invention to provide mechanism of this character that is relatively inexpensive to manufacture. v

The characteristics and advantages of the invention are further suiciently referred to in connection with the following detailed description of the accompanying drawings, which represent one embodiment. After considen. ing this example, skilled persons will understand that many variations may be made without departing from the principles disclosed, and I contemplate the employment of any structures, arrangements, or modes of operation that are properly within the scope ofthe appended claims. Referring to the drawings, which are for illustrative purposes only:

FIG. 1 is a sectional view of -a portion of an internal combustion engine provided with a carburetor embodying the present invention;

FIG. 2 is a perspective view of a carburetor embodying the present invention, portions of the carburetor being broken away to show the interior construction;

valve, in an open position;

FIG. 5 is a side view of the carburetor with the throttle in a partly open position;

FIG. 6 is a similar view with the throttle in the idle 'position with the engine in operation; and

FIG. 7 is a sectional view similar to FIG. 3 but showing an alternative arrangement. K

Referring more particularly to FIG. 1, there is shown a portion of an internal combustion engine, indicated AUnited States Patent Ofce cnl .generally'at 10, `of the two-cycle type. This engine includes a cylinder 11 having a cylinder lining 12 secured therein in the usual well known manner. A portion of the crankcase, indicated at 14, has a-crankshaft 15 of the usual well known character connected to a piston 16 Aby the usual connecting rod '17. The piston 16 is opera-blyy disposed within the cylinder lining 12 ,which may be considered the actual cylinder. Thecrankshaft has the usual counterweight 18. r

An intake manifold 2,0 is secured to the engine in any` well known manner, such as by screws, not shown. Between the manifold 20 and the adjacent portion of the engine is a gasket 21 and a reed valve 22 of well known type. Since the reed valve construction is of known character, it is not believed to req-uire further description. Suice it to say that the reed valve opens vwhen there is suction in the crankcase to permit the inow into opposite sides of the induction passage.

the crankcase of the fuel mixture. In the engine 'shown there is a chamber 23 in which the reed valve is located and said chamiber communicates with the crankcase interior 14. Chamber 23 also communicates with the interior of the cylinder through a port 24 located so as to be uncovered when the piston is Aat its inward limit of movement. Opposite the port 24 there is a similar port 25 which is connected with the interior of the crankcase by a passa-ge 26. Port 25 is located vso as to also be uncovered by the piston when the piston has approached its inward limit of movement. At the outer end of the cylinder there is a combustion chamber, 28 and the head of the cylinder and sides are cooled by fins 29 of the usual character for an air-cooled engine.

Intake manifold 20 has an inlet pont 30 at one side and a carburetor, indicated generally at 32, is attached thereto in the usual manner with screws, not shown, received in openings 33 of an attachment flange 34, the mixture outlet 36 of the carburetor discharging into the inlet port 30 of said intake manifold 20.

'Phe carburetor has the usual induction passage with an air inlet portion 37, large and

small venturies

38 and 39, respectively, in which the fuel and air is mixe-d, and the a'bove referred to mixture outlet portion 36.

A disc-type of throttle valve 40 is mounted on a throttle shaft 41 which extends through the induction passage and is rotatably mounted in suitable bosses 42 and 43 at The throttle shaft 41 is above the axial center line of the induction passage and the throttle valve disc or butterfly 40 is mounted in offset relation on the throttle shaft in an unbalanced manner with the greater percentage of its area located below the throttleshaft.

The carburetor is provided with a fuel chamber 46 which is supplied with fuel through a fuel passage 47 controlled by a needle valve 48, the latter being controlled in the usual manner by a diaphragm mechanism 50. The main fuel nozzle or jet 51 is located to discharge into thesmall venturi 39 and a fuel mixture is discharged i from said venturi into the main or large venturi 38. The

main fuel nozzle or jet 5l is supplied with fuel through a passage 52 from the fuel chamber 46 into a chamber 53, through a disc 54 having an opening 54a therein, there being a check valve member or ball 54h permitting fuel flow through said opening 54a into the chamber 5S withwhich the main fuel nozzle or jet S1 is directly connected, reverse flow through opening 54a being prevented by said ball 54h. A needle valve 56 provides means for adjusting the amount of fuel supplied to the main fuel nozzle or jet 5l.

The carburetor is also provided with an idling system which includes idle jets 60 and 61 which discharge into the induction passage at the lower end of the large venturi 38, said idle jets being longitudinally spaced apart relative to the induction passage. Fuel is supplied from he fuel chamber 46 to said idle jets by way of a fuel pasage 62 which is connected with a chamber 63 having a lirect connection with the idle jets. A needle valve 64 s provided to regulate the supply of fuel from the fuel `hamber 46 to the chamber 63 and hence the idle jets.

When the throttle valve is in the closed or the idling osition the idle jets 60 and 61 are at opposite sides of he lower end of said ythrottle valve and supply idling fuel o the induction passage in the usual well known manner. yVhen the throttle valve is moved to an open position the owcr. edge thereof passes the idle jet 60 so that both idle :ts are downstream of said throttle valve and the control f the fuel and fuel mixture in the carburetor is effected in he usual well known manner and further description hereof is believed to be unnecessary.

A coil spring 70 is disposed on one end of the throttle haft and one end of said spring is fixed or fastened to a crew 71screwed into the boss 42 of the carburetor.

Attached to the same end of the throttle valve is a isc 73 having a plurality of peripheral notches A74. .pring 70 lhas a hook 75 at its free end and said hook is `isposed in one of the notches 74, the tension of said pring being adjusted by relocating the spring end 1'5 in espective notches 74. The disc 73 is also provided with radial arm 76 which is engaged by the inner end 77 of n idle speed adjustment screw 78 which is threadably lisposed in a tapped opening, not shown, provided thereor in a part 79 of the carburetor body. The usual spring is provided on the adjustment screw to retain same in `djusted positions.

The disc 73 is also provided with a radial arm 81 which Irovides a lever spaced circumferentially from the arm '6. A lthrottle rod 82 is slidably disposed in a boss 83 ormed in the carburetor body and said rod 82 is coniected to the usual throttle control mechanism. The end if rod 82 adjacent the disc 73 has a laterally turned porion 82a which is disposed between the

arms

76 and 81.

The

arms

76 and 81 are angularly spaced apart a sutiizient distance so that there is lost motion between said irms and the laterally turned portion 82a of the throttle od 82.

The throttle valve 40 is urged in the opening direction y spring 70, the opening of the throttle valve being imited by engagement of the arm 81 with said laterally urned portion 82a of the throttle rod. When the throttle nechanism is in the idle position the throttle valve will be n the partially open position, such as shown in FIGS. 3 ind 4, for example.

When the engine is started there is a liow of air through he induction passage and this air flow picks up fuel for he fuel mixture in the usual well known manner. Since he throttle valve is partially open at the time the engine s started, adequate fuel will be supplied to provide a luiek start. As soon as the engine starts the vair flow hrough the induction passage increases and this flow endsto close the throttle valve since the greater area of his valve is located at the upstream side of the throttle valve. when said valve is open. The force of the spring '0 tends to balance the force of air ow effective on the hrottle valve, urging same in the closing direction and )y adjusting the spring force the force of the air ow and `pring will be brought to a balance at any desired idle .peed. Thus the idle speed will be governed by the hrottle valve of the carburetor.

When it is desired to accelerate the engine the accel- :rator mechanism thereof is actuated and thereby causes he rod 82 to move in a valve-opening direction. Be- :ause of the spring 70 the arm 81 will follow the laterally urned portion 82a of the rod 82, so that the throttle falve will open in accordance with the opening movenent of the rod 82.

Should the spring 70 be arranged so as not to fully )pen the throttle valve as the throttle rod 82 moves in the )pening direction, the laterally turned end portion 82a )f said rod 82 will engage the arm 76 and positively move the throttle valve further open. Closing movement of the throttle rod 82 will cause the portion 82a thereof to engage the arm 81 and positively move the throttle in the closing direction. Airflow on the larger area of the. throttle valve will also tend to move same in the closing direction.

In the arrangement shown in FIG. 7 there is no small venturi within the induction passage. Otherwisel the mechanism is the same as that shown in the other figures.

The invention and its attendant advantages will be' understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of theY parts of the invention without departing from the spin't and scope thereof or sacrificing its material advantages, the arrangements hereinbefore described being merely for purposes of illustration.

I claim:

l. A carburetor for an internal combustion engine,

comprising:

(A) a carburetor body having an induction passage therethrough, said induction passage having an air inlet and an air-fuel mixture outlet;

(B) venturi means in said induction passage;

(C) a rotatable throttle shaft extending through said induction passage downstream of said venturi means;

(D) a throttle valve disc in said induction passage, said disc being attached in offset relation to said throttle shaft with the greater area of said valve extending upstream in the induction passage when said valve is in an open position;

(E) a spring anchor disc secured to said throttle shaft exteriorly of said carbureor body, said anchor disc having a plurality of peripheral notches therein,

(a) an idle adjustment arm on said disc, said arrn extending outwardly thereof,

(b) and a lever extending outwardly of said dise in circumferentially spaced relationship to said arm;

(F) a coil spring on said throttle shaft, said spring having one end fixed and having a hook at the other end hooked in one of the notches of said spring anchor disc, said spring urging said shaft in a valve opening direction;

(G) an idle adjustment screw cooperable with the idle adjustment arm of the disc for limiting closing movement of the throttle valve;

(H) accelerator means including a part disposed between said arm and said lever of said disc, there being a limited amount of lost motion between said part of the accelerator means and the arm and lever of said disc; and

(I) means defining a fuel system for the engine, said fuel system including (a) a main fuel jet discharging into said venturi means,

(b) and a pair of idle jets disposed downstream of said main fuel jet and located at opposite sides of the throttle valve when the latter is in the closed position.

2. A carburetor for an internal combustion engine,

comprising:

(B) large and small venturi means in said induction passage;

(D) a throttle valve disc in said induction passage, y said disc being attached in offset relation to said throttle shaft with the greater area of said valve extending upstream in the induction passage when said valve is in an open position;

(E) a spring anchor disc secured to said throttle `shaft exteriorly of said carburetor body, said anchor disc having a plurality of peripheral notches therein,

(a) an idle adjustment arm on said disc, said` (G) an idle adjustment screw cooperable with them.

idle adjustment arm of the disc for limiting closing movement of the throttle valve; (H) accelerator means including a part disposed be tween said arm and said lever of said disc, there being a limited amount of lost motion between said part of the accelerator means and the arm and lever of said disc; and (I) means defining a fuel system for the engine, said fuel system including (a) a main fuel jet discharging into said small venturi means,

3. A careburetor for an internal combustion engine,

comprising:

(A) a carburetor `body having an induction passage therethrough;

(B) a rotatable throttle shaft extending through said induction passage;

(C) an offset throttle valve disc in said induction passage carried by said shaft and having the greater area of said valve extending upstream in the induction passage, when said valve is in an open position;

(D) a disc member secured to said throttle shaft exteriorly of 'said carburetor body, said disc having, (a) a radially extending idle adjustment arm, (b) and a radially extending lever in angularly Y spaced relationship to said arm;

(E) a spring for urging said shaft in-a valve opening direction, said spring having one end xed and its lother end variably connectable with said disc to change the effective spring force;

(F) an idle adjustment screw cooperable with the idle adjustment. arm of the disc for closing movement of the throttle valve;

(G) accelerator means including a movably adjustable part disposed in the angular space between said arm and said lever; and

(H) main and idling fuel jets for discharging fuel into said induction passage.

4. A carburetor according to claim 3, wherein the movable part of the accelerator means is inl the paths of movement of said arm and said lever, said part providing an adjustable stop for said lever and being movable into engagement with said arm to move the throttle valve in an opening direction. f

References Cited by the Examiner HARRY B. THORNTON, Primary Examiner.

RONALD R. WEAVER, Examiner.

Claims

3. A CAREBURETOR FOR AN INTERNAL COMBUSTION ENGINE, COMPRISING: (A) A CARBURETOR BODY HAVING AN INDUCTION PASSAGE THERETHROUGH; (B) A ROTATABLE THROTTLE SHAFT EXTENDING THROUGH SAID INDUCTION PASSAGE; (C) AN OFFSET THROTTLE VALVE DISC IN SAID INDUCTION PASSAGE CARRIED BY SAID SHAFT AND HAVING THE GREATER AREA OF SAID VALVE EXTENDING UPSTREAM IN THE INDUCTION PASSAGE, WHEN SAID VALVE IS IN AN OPEN POSITION; (D) A DISC MEMBER SECURED TO SAID THROTTLE SHAFT EXTERIORLY OF SAID CARBURETOR BODY, SAID DISC HAVING, (A) A RADIALLY EXTENDING IDLE ADUSTMENT ARM, (B) AND A RADIALLY EXTENDING LEVER IN ANGULARLY SPACED RELATIONSHIP TO SAID ARM; (E) A SPRING FOR URGING SAID SHAFT IN A VALVE OPENING DIRECTION, SAID SPRING HAVING ONE END FIXED AND ITS OTHER END VARIABLY CONNECTABLE WITH SAID DISC TO CHANGE THE EFFECTIVE SPRING FORCE; (F) AN IDLE ADJUSTMENT SCREW COOPERABLE WITH THE IDLE ADJUSTMENT ARM OF THE DISC FOR LIMITING CLOSING MOVEMENT OF THE THROTTLE VALVE; (G) ACCELERATOR MEANS INCLUDING A MOVABLY ADJUSTABLE PART DISPOSED IN THE ANGULAR SPACE BETWEEN SAID ARM AND SAID LEVER; AND (H) MAIN AND IDLING FUEL JETS FOR DISCHARGING FUEL INTO SAID INDUCTION PASSAGE.