US3199530A - Self-governing carburetor - Google Patents

Self-governing carburetor Download PDF

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Publication number
US3199530A
US3199530A US329614A US32961463A US3199530A US 3199530 A US3199530 A US 3199530A US 329614 A US329614 A US 329614A US 32961463 A US32961463 A US 32961463A US 3199530 A US3199530 A US 3199530A
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Prior art keywords
inertia member
valve
throttle valve
governor
engine
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US329614A
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Ib H Svendsen
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Briggs and Stratton Corp
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Briggs and Stratton Corp
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M19/00Details, component parts, or accessories of carburettors, not provided for in, or of interest apart from, the apparatus of groups F02M1/00 - F02M17/00
    • F02M19/12External control gear, e.g. having dash-pots
    • F02M19/122Damping elements
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D9/00Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D2700/00Mechanical control of speed or power of a single cylinder piston engine
    • F02D2700/02Controlling by changing the air or fuel supply
    • F02D2700/0217Controlling by changing the air or fuel supply for mixture compressing engines using liquid fuel
    • F02D2700/0225Control of air or mixture supply
    • F02D2700/0228Engines without compressor
    • F02D2700/023Engines without compressor by means of one throttle device
    • F02D2700/0235Engines without compressor by means of one throttle device depending on the pressure of a gaseous or liquid medium
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00Fluid handling
    • Y10T137/6851With casing, support, protector or static constructional installations
    • Y10T137/7043Guards and shields
    • Y10T137/7062Valve guards
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00Fluid handling
    • Y10T137/7722Line condition change responsive valves
    • Y10T137/7748Combustion engine induction type
    • Y10T137/7753Unbalanced pivoted valve [e.g., unbalanced butterfly type]

Definitions

  • This invention has achieved this objective through the provision of a relatively small inertia member so connected with the unbalanced valve that despite its small size it efiectively damps out any tendency of the unbalanced valve to flutter, and does so without interfering with quick adjustment of the valve needed to maintain a predetermined engine speed during rapid changes in the load upon the engine.
  • An advantage of this invention is that the entire governor-throttle assembly can be enclosed to protect the same against dirt and other environmental foreign matter which could cause malfunctioning of the device; and with a view toward utilizing this advantage to the fullest extent without interfering with adjustment of the governor to maintain different maximum engine speeds, it is another object of this invention to provide the carburetor body, which is preferably a die casting, with a housing or casing in which the mechanism of the device is located; and further to provide a speed adjusting lever operatively connected with the governor mechanism inside the housing or casing, and passing through a wall of the housing in a way that permits adjustment of the lever from outside the housing or casing, while keeping the housing or casing closed.
  • Still another object of this invention is to provide a simple means of adjusting the non-linear force-which acts upon and tends to open the throttle valve, and by which this force may be readily set at the factory to maintain a predetermined maximum engine speed despite the inevitable variations in the strength of the spring that produces the force and in the friction losses inherent in the medium.
  • FIGURE 1 is a perspective view of a combined carburetor and engine governor embodying this invention, and illustrating the same mounted upon a single cylinder fourstroke cycle engine;
  • FIGURE 2 is a top plan View of the combined carburetor and governor
  • FIGURE 3 is an enlarged top view of a portion of the combined carburetor and governor having parts thereof broken away and shown in section to better illustrate details of the structure;
  • FIGURE 4 is a detail sectional view through FIGURE 3 on the plane of the line 4-4;
  • FIGURE 5 is a diagrammatic view illustrating the manner in which the connection between the unbalanced throttle valve and the inertia member functions to achieve the objectives of this invention
  • FIGURE 6 is a top view of a portion of the combined carburetor and governor, illustrating a modified embodiment of the invention
  • FIGURE 7 is a diagrammatic view similar to FIG- URE 5, but concerned with that form of the invention shown in FIGURE 6;
  • FIGURE 8 is a top plan view of the combined carburetor and engine governor of this invention, illustrating one way in which the mechanism of the device may be fully enclosed to protect the same against environmental dirt and foreign matter, a portion of the enclosing housing or casing being broken away;
  • FIGURE 9 is a sectional View through FIGURE 3 on the planes of the line 99;
  • FIGURE 10 is an exploded perspective view of the spring adjusting means employed in the structure shown in FIGURES 8 and 9;
  • FIGURE 11 is aside view of the housing or casing in which the control mechanism is enclosed, illustrating another way in which the governor spring may be adjusted from outside the housing, part of said view being broken away and in section.
  • the numeral 7 designates generally the hollow body of a carburetor especially adapted for use on single cylinder four-stroke cycle internal combusion engines.
  • the carburetor is mounted on the engine cylinder 8 over its intake port, to supply gaseous fuel mixture thereto during each intake stroke of the piston.
  • the carburetor body 7 has an upwardly facing air inlet 9 over which an air cleaner (not shown) is mounted in the customary manner to clean the air drawn into the carburetor.
  • a choke valve indiareas-2a cated generally by the numeral 10 is mounted in the outer end of the carburetor body to control the admission of air to the carburetor.
  • Fuel contained in a fuel tank 11 is fed into the air passage of the carburetor body through ports 12 and 13, the fuel being drawn through these ports by engine suction in the customary manner, through both of them at the same time when maximum fuel is needed and through only the smaller port 13 when the engine is idling.
  • a needle valve 14 controls the admission of fuel to the ports 12 and 13.
  • a throttle valve 15 Inside the air passage of the carburetor body is a throttle valve 15.
  • This valve comprises a disc of a size and shape to substantially close the air passage when the valve is in the diagonal position shown in FIGURES 2 and 3; but, contrary to customary practice, the valve 15 is unbalanced, i.e. it rotates about an axis which is not symmetrically disposed with respect to the air passage, but instead'is located a substantial distance from the center of the passage. In fact, the axis about which the throttle valve swings is approximately tangent to one side of the passage.
  • the throttle valve 15 is fixed to a shaft 16 by means of an arm 17, the shaft 16 being journalled in bearings integral with the carburetor body and located at the side thereof substantially opposite the needle valve 14 of the carburetor.
  • the throttle valve 15 not only regulates the quantity of fuel-air mixture delivered to the cylinder, but in its idling position it also meters and effects a desirable dilution of the fuel being drawn into the air passage of the carburetor.
  • the throttle valve when the throttle valve is in its idling position substantially closing the port 13, there is little or no suction at the port 12 tending to draw fuel into the air passage. Instead, the suction downstream of the throttle valve and manifested at the port 13, sucks air through the port 12 and admixes it with the fuel to reduce the richness of the mixture drawn into the engine.
  • the throttle valve performs three separate functions: it regulates the flow of fuel-air mixture into the engine; it meters and controls the richness of the fuel mixture drawn into the air passage during idling; and, third, it serves as the sensing means for the governor.
  • this inertia member keeps the throttle valve from fluttering even at low engine speeds when the tendency to produce fluttering is greatest.
  • this inertia member designated 19 on the drawings, is simply a metal disc approximately two inches in diameter and one-quarter of an inch thick, mounted to rotate freely about an axis parallel to that of the throttle valve shaft 16, and preferably intersecting the axis of the air passage through the carburetor body.
  • a motion-transmitting and multiplying connection exists between the throttle valve and the inertia member so that the valve cannot move without imparting rotation to the inertia member.
  • This motion-transmitting and multiplying connection comprises a plurality of interconnected motion-transmitting elements, specifically an arm 29 fixed t0 the throttle valve shaft 16 so as to move in unison with the throttle valve, and a link 21 having one end pivotally connected to the outer end of the arm 24 and its other end pivotally connected to the inertia member, as at 22.
  • the arm 2t constitutes a relatively long crank arm, and the portion of the inertia member lying between its axis of rotation and the point 22 at which the link 21 is attached to the inertia member, constitutes a second and shorter crank arm 23, which for convenience may be identified as the inertia crank.
  • Adjustment of the speed control lever 29 alters the tension of the spring 26 and enables the governor to maintain different engine speeds.
  • the stud 24 is stepped in diameter, having a small diameter threaded end 30 by which the stud is secured in a tapped hole in the carburetor body, and a larger diameter journal portion 31 surmounted by a slotted head 32.
  • a stepped washer 34 Clamped between the shoulder 33 at the junction of the small and large diameter portions of the stud and the upper face of the boss on th carburetor body into which the stud is threaded, is a stepped washer 34.
  • the large diameter upper portion of this stepped washer has substantially the same diameter as the hub 25 of the inertia member so that the adjacent convolutions of the spring 26 may encircle it, and its lower small diameter portion provides a journal 35 for the hub of the speed control lever 29.
  • a spring washer 37 confined between the hub of the lever 29 and the downwardly facing shoulder at the junction of the large and small diameter portions of the stepped washer, frictionally holds the lever in any adjusted position.
  • pivotal connection 22 is effected between the link 21 and the inertia member
  • the link 21 and the inertia member may consist simply of a headed stud 38 threaded into the underside of the inertia member, and having a stepped diameter to provide a journal portion upon which the link 21 freely pivots.
  • the closed or idling position of the throttle valve is not essential to the operativeness of the device, it is preferable to define the closed or idling position of the throttle valve independently of the valve per se, and also to limit the valve opening motion of the linkage. This may be done by providing an abutment 39 on the carburetor body in position to be engaged by the crank arm when the parts reach their relative positions at which the throttle valve is in its full open position, which in practice it seldom if ever reaches, and another abutment 40 on the underside of the inertia member in possition to collide with the link 21 when the valve is in its closed or idling position.
  • biasing force provided by the spring is nonlinear in its effect upon the valve so as to offset the nonlinearity of the hydrostatic and hydrodynamic forces acting upon the valve.
  • FIGURE 5 of the drawings speaks for itself in its portrayal of how and why the motion-transmitting connection between the throttle valve and the inertia member and spring accomplishes these results, to preclude any question in this regard, note that when the valve is in its idling position and the engine-produced forces acting upon the valve are maximum, the crank 23 is nearly in line with link 21 so that the ratio of inertia of member motion to throttle valve motion is largest; that the ratio of the lever arm M-M of the crank 20 to the lever arm mm' of the crank 23 changes as the throttle valve moves from one extreme to the other, being greatest when the valve is in its idling position and smallest when the valve reaches the open position beyond which it seldom or ever goes in practice and which is approximately five degrees from the absolute open position shown in dotted lines in FIGURE 5; and that during all but this last five degrees of opening motion of the valve, the lever arm MM is longer than the lever arm m-m, being considerably longer during the major part of the motion.
  • the inertia changes from almost infinity at the time that the engine-produced forces acting upon the throttle valve are maximum, to considerably less than infinity asthe throttle valve approaches its full open position, and since the motion of the inertia member is multiplied with respect to that of the valve throughout almost the entire range of motion, due to the difierence in the lengths of the lever arms M-M' and m-m', it is possible for the relatively small inertia member to effectively prevent fluttering of the throttle valve under all engine-operating conditions; and because of the small size of the inertia member, the desired prompt response of the throttle valve needed to maintain a predetermined engine speed during rapidly changing load conditions is assured.
  • the invention is not limited thereto. Any kind of inertia member tied to the inertia crank 23 to be moved thereby can be employed.
  • the inertia member may be mounted for reciprocation as. it is in the modified embodiment of the invention shown in FIGURE 6.
  • the inertia member is simply a block of metal on a rod or wire 46 which has one end portion thereof slidably received in a guide way 47 on the body of the carburetor, and its other end pivotally connected to one arm 43 of a bell crank, the other arm 49 of which is the equivalent of the inertia crank 23, and hence has the link 21 connected thereto.
  • a significant advantage of this invention is that the entire governor-throttle assembly may be enclosed to protect the same against environmental dirt and other foreign matter and thereby assure proper functioning of the device despite the conditions under which the engine'opcrates. Essentially this desirable attribute stems from the compactness of the mechanism.
  • the body 7 of the carburetor may have a box-like housing 50 cast integrally therewith and disposed on the upper portion thereof to encompass the inertia member 19 and the linkage by which the inertia member is connected with the shaft 16 of the throttle valve.
  • This box-like housing has a bottom wall 51 substantially tangent with the top of the carburetor body, a side wall 52, the upper edge of which lies on a plane slightly above the inertia member, and a cover 53 seated upon and detachably secured to the upper edge of the side Wall.
  • the lever 29' to which one end of the spring is attached has an upwardly projecting finger 54 onits outer end which is embraced by the arms of a bifurcated lever 55 that is journalled in a hole in the cover 53, and has an actuating arm 56 fixed thereto.
  • the lever 55 may have a cylindrical boss 57 freely rotatably journalled in a hole 58 in the cover coaxial with the inertia member, and the actuat ing arm 56 may have a hub 59 overlying the edge of the hole, these parts being secured together by a plurality of spring fingers 6i) which project down from the hub 59, through a non-circular hole 61 in the actuating arm, and have hooks 62 which snap over the edge of the hole 61.
  • the arm 56 may have a Bowden wire (not shown) attached thereto to enable adjustment of the spring tension from a remote point.
  • the top face of the inertia member 19 has its peripheral portion serrated to provide a circular row of radial notches or grooves 65, and the end of the governor spring which is to be attached to the inertia member extends along the bottom of the inertia member, as at 66, and has a hook portion 62 on its outer end to embrace and grip the edge of the inertia member with the free end 68 of the hook seated in one of the notches or grooves 65.
  • the initial adjustment of the mechanism may be quickly and easily effected; and, if desired, the hooked end of the spring may be secured against accidental disengagement from its selected position on the periphery of the inertia memher by applying a bit of epoxy resin or the like to the junction of the spring and the inertia member.
  • FIGURE 11 Another way of enabling the tension of the governor spring to be adjusted'from outside the protecting housing or casing is shown in FIGURE 11.
  • the control lever 29a simply protrudes through a slot 70 in the side wall of the housing, and a boot 71 fitted on the lever and pressed against the inner face of the side wall by a spring '72, closes the portion of the slot not occupied by the lever.
  • said elements together having considerably less inertia than the inertia member and being so constructed and arranged that they non-linearly translate said motion of the throttle valve into motion of the inertia member in such manner that the ratio of inertia member motion to throttle valve motion is large when the throttle valve is nearly closed and small when the throttle valve is nearly wide open, so that the dynamic resistance to motion which the inertia member imposes upon the valve is maximum when the engine produced forces tending to close the valve are strongest and minimum when those forces are weakest.
  • a second crank connected with the inertia member has a fuel admission port opening to the inside of the duct at a point so located that the edge portion of the throttle valve which is farthest from the axis about which the valve turns covers said port when the valve is closed,
  • the structure of claim .2 wherein the throttle valve is mounted by means of an arm projecting from its upstream side, and the arm is of such length that in its open position the throttle valve occupies a position edgewise substanstantially in line with the axis of the duct.
  • cranks and the link are of such relative lengths and so oriented with respect to the valve and the axis about which the second crank turns that when the valve is in its closed position the eifective lever arm of the first crank is considerably longer than the effective lever arm of the second crank;
  • the structure of claim 8 wherein the relatively fixed anchor is adjustable to enable adjustment of the governor to maintain different engine speeds.
  • the structure of claim 1 wherein (A) the inertia member is rotatably mounted and turns about an axis which is fixed with respect to the axis of the valve, further characterized by (B) a speed adjusting lever mounted to turn about the axis of the inertia member; and
  • biasing means comprises a torsion spring having one end attached to said lever and its other end attached to the inertia member.
  • one of said motion transmitting elements is a crank mounted to turn about an axis fixed with respect to that of the valve, and wherein (C) the inertia member is connected with said crank to be moved thereby.
  • the structure of claim 1 further characterized by means on the duct which supplies the fuel mixture to the engine, defining a housing enclosing the inertia member and the interconnected motion transmitting elements to protect the same from environmental dirt and foreign matter.
  • the inertia member is a disc having a circular periphery, rotatably mounted to turn about an axis which is fixed with respect to the axis of the valve, further characterized by (B) a speed adjusting lever mounted to turn about the axis of the inertia member; wherein (C) the biasing means comprises a torsion spring having one end attached to said lever and its other end attached to the inertia member, and wherein the end of the spring which is attached to the inertia member is shaped to grip the peripheral edge portion of the inertia member at any selected point about its circumference.
  • the inertia member overlies an exterior wall of the duct which supplies the fuel mixture to the engine
  • the speed adjusting lever has a hub portion interposed between the inertia member and said wall of the duct
  • the torsion spring is interposed between the hub portion of the speed adjusting lever and the adjacent side of the inertia member with one end thereof extending along the adjacent side of the inertia memher and terminating in a hook portion which embraces the peripheral edge portion of the inertia member and has its extreme end portion overlying the opposite side of the inertia member
  • said opposite side of the inertia member has a circular row of notches in its peripheral portion in any one of which the extreme end portion of the spring may engage.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)

Description

1965 1. H. SVENDSEN 3,199,530
SELF-GOVERNING CARBURETOR Filed Dec. 5, 1963 5 Sheets-Sheet l Aug. 10, 1965 l. H. SVENDSEN 3,1 3
SELF-GOVERNING CARBURETOR Filed DeC. 5, 1963 5 Sheets-Sheet 2- mdwfiw J7: H Eva-110 5221 Aug. 10, 1965 H. SVENDSEN 3,199,530
SELF-GOVERNING CARBURETOR Filed Dec. 5, 1963 5 Sheets-Sheet 3 lb H. Svsndssn Aug. 10, 1965 I. H. SVENDSEN SELF-GOVERNING CARBURETOR 5 Sheets-Sheet 4 Filed Dec. 5, 1963 dmJwgow lb H Eva-11:75am
Aug. 10, 1965 1. H. SVENDSEN 3,199,530
SELF-GOVERNING CARBURETOR Filed Dec. 5, 1963 5 Sheets-Sheet 5 United States Patent 3,199,539 SELF-GOVEIG CARBURE'IOR lb H. Sveudsen, Bjerringbro, Denmark, assignor to Briggs & Stratton Corporation, Milwaukee, Wis., a corporation of Delaware Filed Dec. 5, I963, Ser. No. 322614 Claims. (Cl. 137-382) This invention, like that of the copending application of Ib H. Svendsen, Serial No. 196,300, filed May 21, 1962, now abandoned, of which this is a continuation-in-part, relates broadly to governors for internal combustion engines, and has as its purpose to provide a governor which will perform satisfactorily on a single cylinder engine, despite the fact that the governor is of the type wherein the hydrostatic and hydrodynamic forces acting upon an unbalanced throttle valve in the duct which supplies the fuel mixture to the engine, imparts a non-linear turning moment to the valve tending to close the same in opposition to a non-linear spring produced biasing force tending to open the valve.
More specifically, it is the purpose and object of this invention to provide an engine governor suitable for use on single cylinder engines, which is an integral part of the carburetor of the engine and in which the throttle valve of the carburetor constitutes the sensing element of the governor.
Engine governors which are actuated by a sensing element responsive to changes in intake manifold pressure are, of course, well known; and even the combination of such governors with the carburetor of the engine is not broadly new, being disclosed for instance in the Fageol et al. Patent No. 2,300,378. However, as far as is known, this type of governor has never before been successfully used on single cylinder engines. The reason no doubt lies in the very pronounced pressure pulsations in the intake manifold of such engines and the fact that these pulsations are relatively widely spaced, occurring only once every two revolutions of the crankshaft in a single cylinder, four-stroke cycle engine.
Because of these pronounced pressure pulsations, an unbalanced throttle valve subjected thereto will flutter hopelessly unless the pulsating effect of the hydrostatic and hydrodynamic forces on the valve is adequately damped out. Various means can, of course, be used in an erfort to keep the valve from fluttering, but to accomplish this purpose in a way which is compatible with the concept of a governor built into the carburetor of a small portable engine, presented a problem which heretofore had not been solved. This invention has achieved this objective through the provision of a relatively small inertia member so connected with the unbalanced valve that despite its small size it efiectively damps out any tendency of the unbalanced valve to flutter, and does so without interfering with quick adjustment of the valve needed to maintain a predetermined engine speed during rapid changes in the load upon the engine.
An advantage of this invention is that the entire governor-throttle assembly can be enclosed to protect the same against dirt and other environmental foreign matter which could cause malfunctioning of the device; and with a view toward utilizing this advantage to the fullest extent without interfering with adjustment of the governor to maintain different maximum engine speeds, it is another object of this invention to provide the carburetor body, which is preferably a die casting, with a housing or casing in which the mechanism of the device is located; and further to provide a speed adjusting lever operatively connected with the governor mechanism inside the housing or casing, and passing through a wall of the housing in a way that permits adjustment of the lever from outside the housing or casing, while keeping the housing or casing closed.
Still another object of this invention is to provide a simple means of adjusting the non-linear force-which acts upon and tends to open the throttle valve, and by which this force may be readily set at the factory to maintain a predetermined maximum engine speed despite the inevitable variations in the strength of the spring that produces the force and in the friction losses inherent in the medium.
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 several complete examples of the physical embodiment of the invention constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:
FIGURE 1 is a perspective view of a combined carburetor and engine governor embodying this invention, and illustrating the same mounted upon a single cylinder fourstroke cycle engine;
FIGURE 2 is a top plan View of the combined carburetor and governor;
FIGURE 3 is an enlarged top view of a portion of the combined carburetor and governor having parts thereof broken away and shown in section to better illustrate details of the structure;
FIGURE 4 is a detail sectional view through FIGURE 3 on the plane of the line 4-4;
FIGURE 5 is a diagrammatic view illustrating the manner in which the connection between the unbalanced throttle valve and the inertia member functions to achieve the objectives of this invention;
FIGURE 6 is a top view of a portion of the combined carburetor and governor, illustrating a modified embodiment of the invention;
FIGURE 7 is a diagrammatic view similar to FIG- URE 5, but concerned with that form of the invention shown in FIGURE 6;
FIGURE 8 is a top plan view of the combined carburetor and engine governor of this invention, illustrating one way in which the mechanism of the device may be fully enclosed to protect the same against environmental dirt and foreign matter, a portion of the enclosing housing or casing being broken away;
FIGURE 9 is a sectional View through FIGURE 3 on the planes of the line 99;
FIGURE 10 is an exploded perspective view of the spring adjusting means employed in the structure shown in FIGURES 8 and 9; and
FIGURE 11 is aside view of the housing or casing in which the control mechanism is enclosed, illustrating another way in which the governor spring may be adjusted from outside the housing, part of said view being broken away and in section.
Referring now particularly to the accompanying drawings, the numeral 7 designates generally the hollow body of a carburetor especially adapted for use on single cylinder four-stroke cycle internal combusion engines. The carburetor is mounted on the engine cylinder 8 over its intake port, to supply gaseous fuel mixture thereto during each intake stroke of the piston. At its outer end, the carburetor body 7 has an upwardly facing air inlet 9 over which an air cleaner (not shown) is mounted in the customary manner to clean the air drawn into the carburetor. Also as is customary, a choke valve, indiareas-2a cated generally by the numeral 10, is mounted in the outer end of the carburetor body to control the admission of air to the carburetor.
Fuel contained in a fuel tank 11 is fed into the air passage of the carburetor body through ports 12 and 13, the fuel being drawn through these ports by engine suction in the customary manner, through both of them at the same time when maximum fuel is needed and through only the smaller port 13 when the engine is idling. A needle valve 14 controls the admission of fuel to the ports 12 and 13.
Inside the air passage of the carburetor body is a throttle valve 15. This valve comprises a disc of a size and shape to substantially close the air passage when the valve is in the diagonal position shown in FIGURES 2 and 3; but, contrary to customary practice, the valve 15 is unbalanced, i.e. it rotates about an axis which is not symmetrically disposed with respect to the air passage, but instead'is located a substantial distance from the center of the passage. In fact, the axis about which the throttle valve swings is approximately tangent to one side of the passage.
The throttle valve 15 is fixed to a shaft 16 by means of an arm 17, the shaft 16 being journalled in bearings integral with the carburetor body and located at the side thereof substantially opposite the needle valve 14 of the carburetor.
Since the throttle valve 15 is unbalanced, it follows that the hydrostatic and hydrodynamic forces produced by engine suction and obtaining in the carburetor passage during every intake stroke of the engine, tend to move or draw the throttle valve to its closed idling position shown in FIGURES 2 and 3.
Attention is directed to the fact that, in the idling position of the throttle valve, the edge thereof adjacent to the ports 12 and 13 substantially closes the mouth of the port 13. Accordingly, the throttle valve 15 not only regulates the quantity of fuel-air mixture delivered to the cylinder, but in its idling position it also meters and effects a desirable dilution of the fuel being drawn into the air passage of the carburetor. This follows from the fact that when the throttle valve is in its idling position substantially closing the port 13, there is little or no suction at the port 12 tending to draw fuel into the air passage. Instead, the suction downstream of the throttle valve and manifested at the port 13, sucks air through the port 12 and admixes it with the fuel to reduce the richness of the mixture drawn into the engine.
Reference has been made to this fuel metering function of the throttle valve to illustrate that in solving the problem to which this invention is directed, the general orientation of the throttle valve in the air passage of the carburetor could not be altered without also providing some other way of metering the fuel during the idling condition. Hence, in this invention, the throttle valve performs three separate functions: it regulates the flow of fuel-air mixture into the engine; it meters and controls the richness of the fuel mixture drawn into the air passage during idling; and, third, it serves as the sensing means for the governor.
The hydrostatic and hydrodynamic forces acting upon the unbalanced throttle valve and tending to close the valve are opposed by an external biasing force applied to the throttle valve. Thus, by regulating this external biasing force, it is possible to set the governor to maintain different engine speeds. However, it has long been recognized that since the forces acting upon the valve and tending to close the same are non-linear, the external biasing force must also be non-linear, and should match the non-linearity of the hydrostatic and hydrodynamic forces.
The manner in which the required non-linearity of the biasing force is obtained with this invention will be hereinafter explained.
The desirability of providing some means of preventing fluttering of the throttle valve has also been recognized in the past-as, for instance, in the aforesaid Fageol et al. Patent No. 2,300,378. However, merely mounting an inertia member upon the shaft of the throttle valve to rotate in unison therewith, as shown in Fageol et al. patent, would be utterly useless for the purpose in a governor for ingle-cylinder engines wherein the suction pulses are relatively widely spaced and a wide pressure differential obtains in the intake passage. An inertia member thus mounted, if large enough to keep the valve from fluttering, would be larger than the engine itself, and would make it impossible for the valve to respond fast enough for any useful purpose.
With this invention, a relatively small inertia member keeps the throttle valve from fluttering even at low engine speeds when the tendency to produce fluttering is greatest. In the preferred embodiment of the invention this inertia member, designated 19 on the drawings, is simply a metal disc approximately two inches in diameter and one-quarter of an inch thick, mounted to rotate freely about an axis parallel to that of the throttle valve shaft 16, and preferably intersecting the axis of the air passage through the carburetor body.
A motion-transmitting and multiplying connection exists between the throttle valve and the inertia member so that the valve cannot move without imparting rotation to the inertia member. This motion-transmitting and multiplying connection comprises a plurality of interconnected motion-transmitting elements, specifically an arm 29 fixed t0 the throttle valve shaft 16 so as to move in unison with the throttle valve, and a link 21 having one end pivotally connected to the outer end of the arm 24 and its other end pivotally connected to the inertia member, as at 22. AS best illustrated in the diagrammatic illustration of FF- URE 5, the arm 2t constitutes a relatively long crank arm, and the portion of the inertia member lying between its axis of rotation and the point 22 at which the link 21 is attached to the inertia member, constitutes a second and shorter crank arm 23, which for convenience may be identified as the inertia crank.
A stud 2 threaded into a boss on the top of the carburetor body rotatably mounts the inertia member, the inertia member having a hub 25 at its underside journalled on the stud; and the external biasing means which acts upon the throttle valve in opposition to the hydrostatic and hydrodynamic forces comprises a torsion spring 25 encircling the hub 25. Gne end 27 of this torsion spring projects into a hole in the underside of the inertia memher, and its other end 28 engages in a hole in the hub of a speed control lever 29 mounted for adjustment about the axis of the stud 24.
Adjustment of the speed control lever 29 alters the tension of the spring 26 and enables the governor to maintain different engine speeds.
As shown in FIGURE 4, the stud 24 is stepped in diameter, having a small diameter threaded end 30 by which the stud is secured in a tapped hole in the carburetor body, and a larger diameter journal portion 31 surmounted by a slotted head 32.
Clamped between the shoulder 33 at the junction of the small and large diameter portions of the stud and the upper face of the boss on th carburetor body into which the stud is threaded, is a stepped washer 34. The large diameter upper portion of this stepped washer has substantially the same diameter as the hub 25 of the inertia member so that the adjacent convolutions of the spring 26 may encircle it, and its lower small diameter portion provides a journal 35 for the hub of the speed control lever 29. A spring washer 37 confined between the hub of the lever 29 and the downwardly facing shoulder at the junction of the large and small diameter portions of the stepped washer, frictionally holds the lever in any adjusted position.
The manner in which the pivotal connection 22 is effected between the link 21 and the inertia member is of no particular significance, and may consist simply of a headed stud 38 threaded into the underside of the inertia member, and having a stepped diameter to provide a journal portion upon which the link 21 freely pivots.
Although it is not essential to the operativeness of the device, it is preferable to define the closed or idling position of the throttle valve independently of the valve per se, and also to limit the valve opening motion of the linkage. This may be done by providing an abutment 39 on the carburetor body in position to be engaged by the crank arm when the parts reach their relative positions at which the throttle valve is in its full open position, which in practice it seldom if ever reaches, and another abutment 40 on the underside of the inertia member in possition to collide with the link 21 when the valve is in its closed or idling position.
As best shown in FIGURE 5, the special relationship between the axes of the throttle valve shaft and or" the inertia member, the relative lengths of the crank arms 20 and 23, and the orientation of the crank arm 29 with respect to the throttle valve and the length of the link 21, are such that three important results are achieved by the manner in which the throttle valve is connected with the ineria member and the biasing spring:
('1) The inertia resisting the motion of the throttle valve is maximum-in fact, approaches infinitywhen the valve is near its idling position and the hydrostatic and hydrodynamic forces acting thereon are greatest, and is progressively. less effective as the valve approaches its full-open position; and the hydrostatic and hydrodynamic forces acting upon the valve are slight;
(2) The motion of the inertia member is multiplied with respect to that of the valve; and
(3) The biasing force provided by the spring is nonlinear in its effect upon the valve so as to offset the nonlinearity of the hydrostatic and hydrodynamic forces acting upon the valve.
Although FIGURE 5 of the drawings speaks for itself in its portrayal of how and why the motion-transmitting connection between the throttle valve and the inertia member and spring accomplishes these results, to preclude any question in this regard, note that when the valve is in its idling position and the engine-produced forces acting upon the valve are maximum, the crank 23 is nearly in line with link 21 so that the ratio of inertia of member motion to throttle valve motion is largest; that the ratio of the lever arm M-M of the crank 20 to the lever arm mm' of the crank 23 changes as the throttle valve moves from one extreme to the other, being greatest when the valve is in its idling position and smallest when the valve reaches the open position beyond which it seldom or ever goes in practice and which is approximately five degrees from the absolute open position shown in dotted lines in FIGURE 5; and that during all but this last five degrees of opening motion of the valve, the lever arm MM is longer than the lever arm m-m, being considerably longer during the major part of the motion.
Because the inertia changes from almost infinity at the time that the engine-produced forces acting upon the throttle valve are maximum, to considerably less than infinity asthe throttle valve approaches its full open position, and since the motion of the inertia member is multiplied with respect to that of the valve throughout almost the entire range of motion, due to the difierence in the lengths of the lever arms M-M' and m-m', it is possible for the relatively small inertia member to effectively prevent fluttering of the throttle valve under all engine-operating conditions; and because of the small size of the inertia member, the desired prompt response of the throttle valve needed to maintain a predetermined engine speed during rapidly changing load conditions is assured.
Although the most practical way of using the inertia member no doublt is to have it rotatable about a fixed axis, the invention is not limited thereto. Any kind of inertia member tied to the inertia crank 23 to be moved thereby can be employed. For instance, the inertia member may be mounted for reciprocation as. it is in the modified embodiment of the invention shown in FIGURE 6.
In this modified form of the invention, the inertia member is simply a block of metal on a rod or wire 46 which has one end portion thereof slidably received in a guide way 47 on the body of the carburetor, and its other end pivotally connected to one arm 43 of a bell crank, the other arm 49 of which is the equivalent of the inertia crank 23, and hence has the link 21 connected thereto.
As perhaps best seen in the diagram, FIGURE 7, everything that has been said about the manner in which the motion transmitting and multiplying connection between the valve and the rotatably mounted inertia member 19 achieves the desired results, is equally applicable to an arrangement wherein the inertia member is slid back and forth as the valve position changes, since in each case the same motion transmitting elements are employed.
A significant advantage of this invention is that the entire governor-throttle assembly may be enclosed to protect the same against environmental dirt and other foreign matter and thereby assure proper functioning of the device despite the conditions under which the engine'opcrates. Essentially this desirable attribute stems from the compactness of the mechanism. Thus, as shown in FIGURES 9 and 10, the body 7 of the carburetor may have a box-like housing 50 cast integrally therewith and disposed on the upper portion thereof to encompass the inertia member 19 and the linkage by which the inertia member is connected with the shaft 16 of the throttle valve. This box-like housing has a bottom wall 51 substantially tangent with the top of the carburetor body, a side wall 52, the upper edge of which lies on a plane slightly above the inertia member, and a cover 53 seated upon and detachably secured to the upper edge of the side Wall.
To enable the tension of the spring 26 to be adjusted without detracting from the protection which the housing affords the mechanism, the lever 29' to which one end of the spring is attached has an upwardly projecting finger 54 onits outer end which is embraced by the arms of a bifurcated lever 55 that is journalled in a hole in the cover 53, and has an actuating arm 56 fixed thereto. While the details of this structure are of course susceptible to modification, the lever 55 may have a cylindrical boss 57 freely rotatably journalled in a hole 58 in the cover coaxial with the inertia member, and the actuat ing arm 56 may have a hub 59 overlying the edge of the hole, these parts being secured together by a plurality of spring fingers 6i) which project down from the hub 59, through a non-circular hole 61 in the actuating arm, and have hooks 62 which snap over the edge of the hole 61.
The arm 56, of course, may have a Bowden wire (not shown) attached thereto to enable adjustment of the spring tension from a remote point.
Inasmuch as the strength of the governor spring and the friction losses in the linkage between the inertia mem her and the throttle valve shaft will vary in production, it is desirable to have some way of compensating for these inevitable variables and assuring that the governor will maintain a predetermined maximum engine speed. In the structure shown in FIGURES 8 and 9, this objective is achieved in a very simple manner. As there shown, the top face of the inertia member 19 has its peripheral portion serrated to provide a circular row of radial notches or grooves 65, and the end of the governor spring which is to be attached to the inertia member extends along the bottom of the inertia member, as at 66, and has a hook portion 62 on its outer end to embrace and grip the edge of the inertia member with the free end 68 of the hook seated in one of the notches or grooves 65.
Thus, by simply sliding the hooked end of the spring along the edge of the inertia member, the initial adjustment of the mechanism may be quickly and easily effected; and, if desired, the hooked end of the spring may be secured against accidental disengagement from its selected position on the periphery of the inertia memher by applying a bit of epoxy resin or the like to the junction of the spring and the inertia member.
Another way of enabling the tension of the governor spring to be adjusted'from outside the protecting housing or casing is shown in FIGURE 11. Here the control lever 29a simply protrudes through a slot 70 in the side wall of the housing, and a boot 71 fitted on the lever and pressed against the inner face of the side wall by a spring '72, closes the portion of the slot not occupied by the lever.
From the foregoing description, taken in connection with the accompanying drawings, it will be readily apparent to those skilled in this art that this invention has achieved an objective long sought in the small portable engine fieldnamely, a self-governing carburetor wherein the throttle valve provides the sensing element of the governor, and that, by this achievement, one source of vexatious complaints to engine manufacturers has been eliminated, since there is nothing about the self-governing carburetor of this invention, especially when the mechanism is enclosed in a protective housing, to become fouled up by dirt and accumulations of grass as there is in the conventional vane type governor, nor does it require any motion transmitting part to pass through the crankcase wall.
What is claimed as my invention is:
1. In a governor for internal combustion engines, of the type wherein the pulsating hydrostatic and hydrodynamic forces produccd by the engine and acting upon an unbalanced throttle valve in the duct which supplies the fuel mixture to the engine impart a pulsating nonlinear turning moment to the valve tending to close same, and a baising force-produced non-linear turning moment acts upon the valve tending to open the same, the improvement which comprises:
(A) a movably mounted inertia member;
(B) a plurality of interconnected motion-transmitting elements providing a motion transmitting connection between the throttle valve and the inertia member to at all times translate motion of the throttle valve into motion of the inertia member,
(1) said elements together having considerably less inertia than the inertia member and being so constructed and arranged that they non-linearly translate said motion of the throttle valve into motion of the inertia member in such manner that the ratio of inertia member motion to throttle valve motion is large when the throttle valve is nearly closed and small when the throttle valve is nearly wide open, so that the dynamic resistance to motion which the inertia member imposes upon the valve is maximum when the engine produced forces tending to close the valve are strongest and minimum when those forces are weakest.
2. In a governor for internal combustion engines, the structure of claim 1,
(A) wherein the throttle valve turns about an axis which is close to one side of the duct; and
(B) a second crank connected with the inertia member has a fuel admission port opening to the inside of the duct at a point so located that the edge portion of the throttle valve which is farthest from the axis about which the valve turns covers said port when the valve is closed,
(1) so that the throttle valve in addition to regulating the flow of combustible mixture through the duct also controls the richness of the fuelair mixture.
3. In a governor for internal combustion engines, the structure of claim 2, wherein the axis about which the throttle valve turns is at the upstream side of the throttle valve.
4. In a governor for internal combustion engines, the structure of claim 3, wherein said axis lies outside the passage provided by the duct.
5. In a governor for internal combustion engines, the structure of claim .2, wherein the throttle valve is mounted by means of an arm projecting from its upstream side, and the arm is of such length that in its open position the throttle valve occupies a position edgewise substanstantially in line with the axis of the duct.
' 6. In a governor for internal combustion engines, the structure set forth in claim 1, wherein said interconnected motion-transmitting elements comprises (A) a first crank fixed with respect to the valve,
(*5) a second crank connected with the inertia member and constrained to turn about an axis which is fixed with respect to the axis about which the valve and the first crank turn,
(C) a link connecting the cranks; and wherein (D) the cranks and the link are of such relative lengths and so oriented with respect to the valve and the axis about which the second crank turns that when the valve is in its closed position the eifective lever arm of the first crank is considerably longer than the effective lever arm of the second crank; and
(E) wherein the biasing force is provided by a spring reacting between the inertia member and a relatively fixed anchor.
7. In a governor for internal combustion engines, the structure set forth in claim 6, wherein the inertia member is rotatably mounted and turns about the fixed axis of the second crank.
8. In a governor for internal combustion engines, the structure set forth in claim 1, wherein said biasing force which produces the non-linear turning moment of the throttle valve is provided by a linear spring reacting between a relatively fixed anchor and the inertia member.
9. In a governor for internal combustion engines, the structure of claim 8, wherein the relatively fixed anchor is adjustable to enable adjustment of the governor to maintain different engine speeds.
10. In a governor for internal combustion engines, the structure of claim 1, wherein (A) the inertia member is rotatably mounted and turns about an axis which is fixed with respect to the axis of the valve, further characterized by (B) a speed adjusting lever mounted to turn about the axis of the inertia member; and
(C) wherein the biasing means comprises a torsion spring having one end attached to said lever and its other end attached to the inertia member.
11. In a governor for internal combustion engines, the
structure of claim 1, wherein (A) the inertia member is reciprocably mounted;
wherein (B) one of said motion transmitting elements is a crank mounted to turn about an axis fixed with respect to that of the valve, and wherein (C) the inertia member is connected with said crank to be moved thereby.
12. In a governor for internal combustion engines, the structure of claim 1, further characterized by means on the duct which supplies the fuel mixture to the engine, defining a housing enclosing the inertia member and the interconnected motion transmitting elements to protect the same from environmental dirt and foreign matter.
1.:l. In a governor for internal combustion engines, the structure of claim 12 wherein (A) said biasing force which produces the non-linear turning moment of the throttle valve is provided by a spring reacting between the inertia member and an adjustable relatively fixed anchor,
said relatively fixed anchor and the spring being inside said housing; and
(B) an actuating member connected with the relatively fixed member inside the housing and movably passing through a wall of the housing to provide means for adjusting the position of the relatively fixed member to thereby adjust the tension of the spring as needed to set the governor to maintain different selected speeds.
:14. In a governor for internal combustion engines, the
structure or claim 1 wherein (A) the inertia member is a disc having a circular periphery, rotatably mounted to turn about an axis which is fixed with respect to the axis of the valve, further characterized by (B) a speed adjusting lever mounted to turn about the axis of the inertia member; wherein (C) the biasing means comprises a torsion spring having one end attached to said lever and its other end attached to the inertia member, and wherein the end of the spring which is attached to the inertia member is shaped to grip the peripheral edge portion of the inertia member at any selected point about its circumference.
15. In a governor for internal combustion engines, the
structure of claim 1 wherein (A) the inertia member overlies an exterior wall of the duct which supplies the fuel mixture to the engine, wherein (B) the speed adjusting lever has a hub portion interposed between the inertia member and said wall of the duct; wherein (C) the torsion spring is interposed between the hub portion of the speed adjusting lever and the adjacent side of the inertia member with one end thereof extending along the adjacent side of the inertia memher and terminating in a hook portion which embraces the peripheral edge portion of the inertia member and has its extreme end portion overlying the opposite side of the inertia member; and wherein (D) said opposite side of the inertia member has a circular row of notches in its peripheral portion in any one of which the extreme end portion of the spring may engage.
No references cited.
ISADOR WEIL, Primary Examiner.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,199,530 August 10, 1965 Ib H. Svendsen It is hereby certified that error appears in t ent requiring correction and corrected below.
he above numbered petthat the said Letters Patent should read as Column 5, lines 14 and 15,
for "possition" read position column 7, line 63,
strike out "a second crank tia member" and insert instead 1y opposite side of the duct Signed and sealed this 8th day of March 1966.
VEST W. SWIDER EDWARD J. BRENNER :sting ()fficer Commissioner of Patents

Claims (1)

1. IN A GOVERNOR FOR INTERNAL COMBUSTION ENGINES OF THE TYPE WHEREIN THE PULSATING HYDROSTATIC AND HYDRODYNAMIC FORCES PRODUCED BY THE ENGINE AND ACTING UPON AN UNBALANCED THROTTLE VALVE IN THE DUCT WHICH SUPPLIES THE FUEL MIXTURE TO THE ENGINE IMPART A PULSATING NONLINEAR TURNING MOMENT TO THE VALVE TENDING TO CLOSE SAME, AND A BAISING FORCE-PRODUCED NON-LINEAR TURNING MOMENT ACTS UPON THE VALVE TENDING TO OPEN THE SAME, THE IMPROVEMENT WHICH COMPRISES: (A) A MOVABLY MOUNTED INERTIA MEMBER; (B) A PLURALITY OF INTERCONNECTED MOTION-TRANSMITTING ELEMENTS PROVIDING A MOTION TRANSMITTING CONNECTION BETWEEN THE THROTTLE VALVE AND THE INERTIA MEMBER TO AT ALL TIMES TRANSLATE MOTION OF THE THROTTLE VALVE INTO MOTION OF THE INERTIA MEMBER,
US329614A 1963-12-05 1963-12-05 Self-governing carburetor Expired - Lifetime US3199530A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4023550A (en) * 1974-08-27 1977-05-17 Briggs & Stratton Corporation Engine with overspeed prevention
US4221202A (en) * 1978-06-15 1980-09-09 Outboard Marine Corporation Air vane carburetor with adjustable speed
US6520489B1 (en) * 2001-03-29 2003-02-18 Zama Japan Throttle control for hand-held blowers
US9429107B2 (en) 2013-02-22 2016-08-30 Briggs & Stratton Corporation Solenoid autochoke for an engine
US9932936B2 (en) 2015-11-11 2018-04-03 Briggs & Stratton Corporation Carburetor choke removal mechanism for pressure washers
US9945326B2 (en) 2015-05-07 2018-04-17 Briggs & Stratton Corporation Automatic choking mechanism for internal combustion engines
US10215130B2 (en) 2012-02-10 2019-02-26 Briggs & Stratton Corporation Choke override for an engine

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4023550A (en) * 1974-08-27 1977-05-17 Briggs & Stratton Corporation Engine with overspeed prevention
US4221202A (en) * 1978-06-15 1980-09-09 Outboard Marine Corporation Air vane carburetor with adjustable speed
US6520489B1 (en) * 2001-03-29 2003-02-18 Zama Japan Throttle control for hand-held blowers
US10215130B2 (en) 2012-02-10 2019-02-26 Briggs & Stratton Corporation Choke override for an engine
US9429107B2 (en) 2013-02-22 2016-08-30 Briggs & Stratton Corporation Solenoid autochoke for an engine
US9945326B2 (en) 2015-05-07 2018-04-17 Briggs & Stratton Corporation Automatic choking mechanism for internal combustion engines
US9932936B2 (en) 2015-11-11 2018-04-03 Briggs & Stratton Corporation Carburetor choke removal mechanism for pressure washers

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