US2529244A - Throttle valve for carburetors - Google Patents

Description

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THROTTLE mm FOR CARBURETORS 2 Sheets-Sheet 1 Original Filed Sept. 10, 1949 fiupiz 5' Brawn Warner E Armatrang 0v. 7, 1950 H. 5. BROWN ETAL THROTTLE VALVE FOR CARBURETORS 2 Sheets-Sheet 2 Original Filed Sept. 10, 1949 4712 51 Brawn WEZZZEZ E Armstrong Jassp/z II Hem/792755017 up c 0 I This application is a Patented Nov. 7, 1 950 THROTTLE VALVE FOR CARBURETORS Hugh S. Brown, Wauwatosa, and Werner E. Armstrong and Joseph V. Reichenbach, Milwaukee, Wis., assignors to Briggs & Stratton Corporation, Milwaukee, Wis., a corporation of Delaware Original application September 10, 1949, Serial No. 114,982. Divided and this application July 31, 1959, Serial No. 176,882

7 Claims. (01. 251-152) 1 division of our copending application, Serial Number 114,982, filed September 10, 1949, which claims the general combination of the carburetor.

The present invention relates more particularly to the throttle valve of the carburetor and has as its primary objective the provision of a simplified manner of mounting the throttle valve by which the assembly of the valve with the body is facilitated and die casting of the throttle valve as well as the carburetor body is made possible.

With a view towardachieving this objective it is an object of this invention to provide a carburetor throttle valve of the butterfly type but wherein the valve has a substantially barrel-like formation and is rotatably received in a cylindrical well intersecting the induction passage of the carburetor body and opening to the top thereof.

Another object of this invention is to secure the throttle valve against displacement from the well in which it is seated, by interengageable abutments or surfaces on the valve and the body of the carburetor which block upward displacement of the valve as long as it lies within its normal limits of rotation, but which clear each other when the valve is in a predetermined position of rotation beyond one of its normal limits.

Still another object of this invention is to utilize the idling adjustment screw as one of the stops defining the limits of rotation of the throttle valve, which by its adjustability enables rotation of the valve to the position at which it may be assembled and disassembled from the carburetor body.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed in accordance with the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a perspective view showing a portion of a one cylinder internal combustion engine with a carburetor embodying this invention applied thereto, the air cleaner being omitted in this view;

Figure 2 is a top plan view of the carburetor and throttle valve of this invention;

Figure 3 is a side view of the carburetor, with the air cleaner broken away, and with the fuel tank which is supported from the underside of the carburetor having a portion thereof broken away and in section;

Figure 4 is a cross sectional view taken through Figure 3 on the plane of the line 4-4;

Figure 5 is a horizontal sectional view taken through Figure 3 on the plane of the line 5-5; and

Figure 6 is a detail perspective view of the throttle valve per se.

Referring now particularly to the accompanying drawings in which like numerals indicate like parts throughout the several views, the numeral 5 indicates generally a carburetor of the type described and claimed in the aforesaid parent application, Serial Number 114,982, filed September 10, 1949. The body 6 of the carburetor is an elongated hollow die casting having a longitudinally extending bore 1 opening to one end of the body, and an attaching flange 8 at said end. The attaching flange provides means by which the body is securable to the cylinder 9 of an engine.

The engine, of course, may be of any desired construction with its cylinder either vertical as shown or horizontal. In any-event when the carburetor is secured in place on the cylinder the mouth of its bore 1 which provides a mixture or induction passage opens to the intake port In of the engine and the body 6 projects horizontally outwardly from the cylinder as a rigid load carrying member. I

At its outer end portion the body has a downwardly projecting bracket II having a-flat bottom wall l2. This bracket serves to strengthen the body and its fiat bottom wall provides a gasket flange to which a fuel tank I3 is secured with a gasket H interposed therebetween. The top and bottom walls of the tank are substantially flat and parallel, and the top wall thereof is reinforced by a plate l5 into which the mounting screws are threaded.

The extreme outer end portion of the tubular body has an upstanding hollow boss l6 formed thereon, the hollow interior of which defines a well communicating with the bore 1 through an air inlet opening IS in the bottom thereof. A flange II at the top of this boss provides a base upon which a conventional air cleaner I8 is seated, the air cleaner being held in place in the customary manner by a tension screw 19 extending downwardly through the center thereof and threaded into the body. Thus with the carburetor mounted on the engine cylinder in the manner described engine suction draws air into the outer end of the mixture passage provided by the bore 1. Engine suction also draws fuel from the tank into the mixture passage through a jet indicated generally by the numeral 2|.

The jet 2| is located in a socket 22 extendin axially into a boss 23 formed on the side of the .body. A plurality of orifices 24 provide restricted communication between the jet socket and the mixture passage. and a needle valve seat 25 threaded into the socket coacts with a needle valve 26 to meter the flow of fuel into the mixture passage. Engine suction manifested at the jet draws fuel into the socket 22 outwardly of the needle valve through a suction pipe 21 which extends down through the bottom of the bracket and the top wall of the tank to have its lower open end terminate slightly above the bottom wall of the tank. A screen 28 is preferably secured over the open lower end of the suction pipe to preclude the admission of foreign matter into the pipe. but otherwise the suction pipe is open, no check valve being needed due tothe direct lift suction action.

Adjacent to the point at which the fuel jet opens into the mixture passage the body 6 has an upright cylindrical valve socket or wall 30 intersecting its bore 1. The bottom of this socket or well'is closed but the top is open. Seated in the socket is a barrel-like throttle valve 3|. This valve, like the body 5, is made as a die casting and has upper and lower cylindrical end portions 32 and 33 respectively connected by a flattened middle portion or vane 34. The bottom of the socket is below the bore 1 and its top opens through the top of a boss 35 the upper portion of which forms a circular neck surrounding the mouth of the socket. The cylindrical end portions of the valve are thus journalled in the socket above and below the bore 1 while the fiat middle portion 34 extends directly across the bore to control flow therethrough. Since the valve turns on a vertical axis there is little chance of its binding in the socket, and to further reduce the likelihood of binding, its area of contact with the bottom of the socket upon which it rests is reduced to a minimum through the provision of a small central foot or pad 36 projecting down from the bottom of the valve.

It is to be notedthat the axis about which the throttle valve turns lies in a vertical plane which is normal to the axis of the induction passage and intersects the wall thereof at a point closely adjacent to the orifices 24. Hence one edge of the vane 34 which constitutes the throttle valve the relative effect of engine suction upon air and fuel injection may be varied.

It will also be seen that since the socket 22 lies to one side of the induction passage and is at substantially the same elevation above the top of the fuel tank as the induction passage, the height to which the fuel must be lifted is held to a minimum.

The upper cylindrical end 32 of the valve has a head 3'l formed integrally therewith, the underside of which has an annular groove 38 to receive the neck provided by the upper portion of the boss 35. This interengagement between the neck surrounding the mouth of the valve socket the socket.

Since the body 6 constitutes a load carrying member it is desirable to provide as much rein-,1 forcement therefor as possible. To this end'sijde ribs 39, a top rib 40 and a bottom rib 4! are formed] along the length of the body to merge with the taching flange a. The top rib to is interrupte by the boss which defines the top of the valve socket, and at one side of this boss the rib 401s enlarged to provide a stop 42 and at the other". side thereof the rib is undercut to provide an;

46 with the stop 42, the screw 46 being adjustably threaded in another arm 41 extending radially from the head of the valve. A spring 53 encircling the screw 46 bears against the underside of its head and thus frictionally holds the screw in adjusted position.

As will be readily apparent the adjustability of the screw 4'6 enables the'valve to be turned far enough in a counterclockwise direction (as viewed in Fig. 2) to' bring the segment-like flange 44 clear of the overhanging ledge 43. This manner of securing the valve in position is particularly advantageous in assembly since it merely requires dropping the valve into its socket and threading the screw 46 into proper position.

Inasmuch as the carburetor of this invention is designed especially for use in small portable single cylinder engines which often are called upon to operate entirely unattended, it is desirable to provide an automatic control for the 60 throttle valve to thereby coordinate the speed of the engine with the load imposed thereon. Such controls, of course, are not new in themselves, Patent No. 1,660,079 issued to Perry E. Mack being an example thereof.

As in the aforesaid patent the control here employed also utilizes a vane 56 mounted to be influenced by air pressure emanating from the ventilating fan blades 51 on the fiy. wheel 58 of the engine, this air blast being directed and guided by a shroud 59. The blad 56 which is secured to a hinged actuator arm 60 is adapted to be moved toward the right in Figure 1 by the air blast. Such movement of the blade and arm 60 is imparted to the throttle valve through a wire 5 link 6| to rotate the valve toward its idling posiand the head 31 of the valve provides a free'run-a' ning seal between the valve and the mouth of g 31 of the valve to hold the valve in the socket eiC-i tion and thus slow up the engine whenever the engine speeds up due to a diminishing load.

Though, as will be readily appreciated, the end 01 the wire 6| could be hooked directly to some part of the throttle valve, to simplify the die casting thereof a stamped sheet metal attaching clip 62 is provided for this purpose. This clip is conveniently held in place ,by the idle adjusting screw 46. To this end the clip has a part 64 which overlies and embraces the arm 4'1 on the valve where it is held by the screw 46 'and its holding spring 63.

The response of the governor vane 56 to air pressure is opposed by a spring 85, the tension of which determines the speed at which the engine will run. One end of the spring is hooked into a loop 66 formed in the wire link 6|. Its other end is hooked onto a lever 61 pivoted to swing about a horizontal axis toward and from the spring 65 and securable in different positions of adjustment.

Hence, the throttle valve is moved in one direction by the governor mechanism and in the other direction by the spring 65, but there are no forces acting upon the valve in a way which could cause it to bind in its socket. This feature and the manner in which the spring is adjusted forms the subject matter of our copending divisional application, Serial No. 114,982, filed September 10, 1949.

From the foregoing description taken in connection with the accompanying drawings it will be readily apparent that this invention provides a highly satisfactory manner of mounting the throttle valve of a carburetor, since by virtue of its construction assembly of the valve with the carburetor body requires merely dropping the valve down into its socket, turning it slightly and advancing the screw which provides the idling adjustment; and that by virtue of this arrangement, the valve may be formed as a die casting.

What we claim as our invention is:

1. In a carburetor: a body havingamixture passage; the body having a cylindrical valve socket intersecting the mixture passage; a boss cast integrally with the body adjacent to the mouth of the valve socket, said boss providing a fixed stop abutment; another boss cast integrally with the body adjacent to the mouth of the valve socket and substantially diametrically across the socket from the first boss, the second boss having its portion nearest the valve socket notched to provide a ledge; a throttle valve rotatably seat ed in the socket; a segment-like flange on the outer end of the valve engaged under the ledge to hold the valve in place, disengagement of the flange from under the ledge to permit removal of the valve requiring rotation of the valve beyond one of its normal limits of rotation; an arm extending radially from the valve in position to collide with one side of the fixed stop abutments to define one of the limits of rotation of the valve; another arm extending radially from the valve; and a screw threaded in said other arm and engageable with the other side of the fixed stop abutments to define the other limit of valve rotation, the adjustability of the screw enabling rotation of the valve to the position at which its segment-like flange clears the ledge.

2. In a carburetor: a body having a mixture passage and having a cylindrical valve socket intersecting the mixture passage; a boss integral with the body adjacent to the mouth of the valve socket and having a ledge projecting towards the valve socket; a throttle valve rotatably seated in-the socket; a segment-like flange on the outer end of the valve engaged under the ledge to hold socket; an arm extending radially from the valve in position to collide with one of said fixed stop abutments to define one o1 the limits of rotation oi' the valve; another arm extending radially from the valve; and a screw threaded in said other arm and engageable with the other of said fixed stop abutments to define the other limit 01 valve rotation, the adjustability of the screw enabling rotation of the valve to the position at which its segment-like flange clears the ledge.

3. In a carburetor: a cast body having a horizontal mixture passage; the body having a cy-' lindrical valve socket intersecting the mixture passage and opening upwardly thereof; an abutment cast integrally with the body adjacent to the mouth of the valve socket, said abutment providing fixed stops; a retaining ledge cast integrally with the body adjacent to the mouth of of the valve engaged under the ledge to hold the valve against displacement from the socket as long as the valve remains between its normal limits of rotation; an arm projecting from they valve and positioned to collide with one sideot the abutment to define one of the limits of rotation of the valve; another arm projecting from the valve; and a screw threaded in said other arm and engageable with the other side of the abutment to define the other limit of valve rotation, the adjustability of the screw enabling rotation of the valve to the position at which its flange segment clears the ledge to thereby permit the removal of the valve.

4. In a carburetor for internal combustion engines: an elongated tubular body having a 1ongitudinally extending mixture passage and means for securing the body to an engine cylinder with the mouth of said passage over the intake port of the cylinder and with the body horizontal; an upwardly projecting boss on the. body between its ends; said boss having a cylindrical valve socket communicating with the mixture passage and opening upwardly through the top of the boss, the'upper portion of the boss providing an annular neck surrounding the mouth of the socket; a throttle valve rotatable in the socket and having a head portion overlying the top of the neck, said head having an annular groove in its underside to receive the neck, the interengagement of said annular groove and neck providing a free running seal between the valve and body; interengaging abutments on the body and throttle valve for holding the valve against disassembly from the body except upon rotation of the valve to a predetermined position beyond its normal limits of rotation; and means for defining the normal limits of rotation of the valve, part .of said last named means being adjustable to rotation of the valve member to a position be-.

yond one of its normal limits of rotation; a pair of angularly spaced fixed stop abutments on one of said members; a fixed stop abutment on the other member positioned to collide with one of said pair of stop abutments to define the open position of the valve member; and an idling adjustment screw threaded in said other member with its end positioned to collide with the other of said pair of fixed stop abutments to define the idling position of the valve member, and by its adjustment enabling rotation of the valve member to a position at which the interengaging abutments clear each other.

6. In a carburetor: a body having a mixture passage and a cylindrical valve socket intersecting the mixture passage, said valve socket being closed at the bottom and open at the top; a bare rel-like throttle valve having cylindrical end portions connected by a flattened middle portion rotatably seated in the socket; interengaging abutments on the body and the barrel-like valve for holding the valve against disassembly from the body except upon rotation of the valve to a position beyond its normal limits of rotation; and means for defining the normal limits of rotation of the valve, said means comprising a pair of angularly spaced fixed stop abutments on the body at the mouth oi. the valve socket; an abutment on the valve in position to collide with one of said pair of fixed stop abutments to define one of the limits of rotation of the valve; an arm extending radially from the valve and spaced angularly from said abutment thereon; and a screw threaded in said arm with its end positioned to collide with the other of said pair of fixed stop abutments to define the other limit of valve rotation, the adjustability of the screw enabling rotation of the valve to the position at which said interengaging abutments on the body and valve clear each other.

7. The carburetor of claim 6 further characterized by the fact that said screw also provides the idling adjustment for the carburetor.

HUGH S. BROWN. WERNER E. ARMSTRONG. JOSEPH V. REICHENBACH.

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

UNITED STATES PATENTS Number Name Date 272,732 Mayer Feb. 20, 1883 714,410 Stainton Nov. 25, 1902 849,724 Christ Apr. 9, 1907 1,505,729 Robertshaw Aug. 19, 1924 FOREIGN PATENTS Number Country Date 17,350 Great Britain of 1907

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