US 3350074 A
Description (OCR text may contain errors)
R. E. KALERT, JR, ET AL 3,350,074
LIMITED TRAVEL CARBURETOR METERING ROD Oct. 31, 1967 2 Sheets-Sheet 1 Filed NOV. 8, 1965 FIG.
INVENTORS F I G 2 RALPH E. KALERT. JR. BYDONALD A. REISE ATTORNEY Oct. 31, 1967 -r, JR ET AL 3,350,074
LIMITED TRAVEL CARBURETOR METERING ROD Filed Nov. 8, 1965 2 Sheets-Sheet 2 g F I 3. 3. a7 w) 2 4 s5 INVENTORS "1m 82 RALPH E. KALERT,JR.
DONALD A. REISE BY 52 75 ATTO R NEY United States Patent Filed Nov. 8, 1965, Ser. No. 506,670 4 Claims. (Cl. 261-51) This invention relates to a carburetor. It relates in particular to a carburetor utilizing a controlled metering rod for more accurately regulating flow of fuel to the carburetor mixing conduit.
In carburetors of the type presently contemplated, the flow of fuel passing from the carburetor fuel bowl to the mixing conduit is regulated to some extent by a metering rod positioned in an orifice connecting the source of fuel with the mixing conduit. The primary purpose of a metering rod is to afford the carburetor a higher degree of efiiciency and economy of function under all engine operating conditions.
This is achieved by regulating the position of the metering rod in the orifice to alter the flow of fuel passing into the carburetor discharge nozzle as the demand for fuel is varied by the engine. One such regulating means includes a mechanical linkage connected directly to the carburetor throttle and operable to alter the position of the metering rod directly as the throttle is adjusted. Another means includes a pneumatic or air motor arrangement connected to a source of vacuum such as the engine inlet manifold, whereby variations in manifold vacuum are reflected in a comparable adjustment in the metering rod position.
It has been found that while the fuel metering rods above described are beneficial in many respects to carburetor operation, under some circumstances it is desirable that closer control be exercised to regulate fuel flow and consequently improve engine combustion. Further, where the air motor type arrangement is utilized, the reaction time lapse between the need for a richer air-fuel mixture, and the delivery of sufiicient fuel to provide such a mixture is often excessive. This follows since the usual air motor arrangement is designed to respond proportionately to the degree of manifold vacuum.
It has been found that under certain engine speeds and loads, an excessive fuel delivery to the discharge nozzle results in an over-rich air fuel mixture and the creation of large amounts of unburned hydrocarbons which are discharged to the atmosphere with engine exhaust fumes. Engine operation under such circumstances is not only uneconomical, it also tends to aggravate a frequently present problem of air pollution due to the emission of unburned hydrocarbons and other undesirable matter into the atmosphere.
It is therefore an object of the invention to provide an improved carburetor having fuel metering means adapted to provide a more efiicient and economical air fuel mixture to the engine. It is a further object to provide an automatic control for metering fuel in a carburetor to avoid formation of over-rich air fuel mixtures. Another object is to provide an automatic elongated fuel metering valve and actuating mechanism therefor, automatically adjustable in response to both engine condition and throttle position.
The foregoing objects together with others not specifically enumerated will be clear to those skilled in the art from the following description.
The invention as herein disclosed is directed to a wellknown carburetor construction utilizing a fuel metering rod cooperative with an orifice formed in the base of the fuel well, the latter which forms a portion of the carburetor body. The well portion of the body is disposed within the carburetor fuel bowl. The metering rod is arranged such that the tapered or metering end is operatively positioned within the fuel metering jet.
The upper end of the metering rod is retained in an air motor or similar actuating assembly responsive to both engine manifold vacuum and to the position of the throttle. Thus, the metering rod is connected to a displaceable diaphragm in the air motor which adjusts automatically in response to variations in engine manifold vacuum, which in turn normally corresponds to engine load. The rod is controlled to avoid the normal reaction of the air motor to over-adjust at low engine speeds or rapid deceleration, which would provide an over-rich air fuel mixture to the engine. It is further regulated to assure an adequately rich fuel mixture for automatically maintaining engine speed under road load conditions which would cause a decrease in intake manifold vacuum.
In the figures; FIGURE 1 is a plan view of a car-buretor embodying the novel features of the invention; FIGURE 2 is a substantially longitudinal cross-sectional view of the carburetor shown in FIGURE 1 illustrated on an engine manifold; FIGURE 3 is a segmentary view on an enlarged scale of a portion of the carburetor shown in FIGURE 2; FIGURE 4 is a segmentary view of a portion of the carburetor shown in FIGURE 2; and, FIGURES 5, 6, and 7 are segmentary views of the device shown in FIGURE 3 illustrating the apparatus in various stages of operation.
The invention is presently illustrated as incorporated into the body of a single barrel carburetor similar to that shown in US. Patent 3,189,333. It is understood however, that the following description of the fuel metering device is for the purpose of illustrating a particular structure which may be applied equally as well to other forms of carburetors such as multi-barrel and the like.
Referring to FIGURE 1, the carburetor shown is similar in many respects to that illustrated in US. Patent 3,189,333 and consists essentially of a casting 10, Which is formed with a fuel and air mixture conduit 12, and a fuel =bowl cover portion 14 from which depends an accelcrating pump cylinder 16, an accelerating fuel passage 18, and a fuel well structure 20. Mixture conduit 12 is connected by a flange 13 to intake manifold M of an internal combustion engine E. In the lower part of the conduit 12 there is rotatably mounted a throttle valve 22 fixed to a throttle shaft 24 journalled in appropriately aligned apertures in body casting 10. In the upper portion of the fuel air mixture conduit 12 there is similarly mounted for rotational movement an unbalanced choke valve 26 fixed to a choke valve shaft 28, which is also journalled in aligned apertures through the body casting 10.
The top of mixture conduit 12 is connected to an air filter 29, partially shown in cross-section in FIGURE 2. Between the upper and lower portions of the mixture conduit 12 is formed a venturi or air flow restricting surface portion 30. A small booster venturi 32 is formed integrally with body casting 10 and has an inner venturi surface 34 coaxially aligned with the mixture conduit 12 and the primary venturi surface 30.
A fuel bowl 36 is fixed beneath fuel bowl cover 14 and is held with its rim against a gasket 38 fitted between the rim of the fuel bowl 36 and matching portions of the fuel bowl cover 14. A float structure 40 is pivotally mounted from pin 42 journalled in a depending portion of fuel bowl cover 14. A lever arm of float lever 43 fixed to float 40 abuts the lower end of a needle valve 44 having an upper tapered end extending into a valve seat 46 of the inlet 47 to the fuel bowl 36.
Normally, fuel is forced under pressure by pump 50 from the fuel tank 52, through fuel line 48 and to carburetor inlet 47. When fuel level in bowl 36 is low, float 40 drops commensurably and lever arm 43 permits valve 44 to be displaced to an open position under fuel pressure. Fuel then flows into bowl 36 until reaching a predetermined level. The needle valve 44 is closed by the upward urging of fioat lever 43 as the fuel level rises.
Referring to FIGURE 3, the lower end of fuel well 20 is closed by a threaded fitting 56 having a central orifice 69 which is formed to provide a metering jet for the flow of fuel from the fuel bowl 36 to mixture conduit 12. A screw driver slot 57 is provided in the bottom of fitting 56 to permit its removal. The upper end of fuel well 20 intersects fuel passage 58 directed downwardly into secondary venturi 32. A nozzle fitting 60 is held in the end of passage 58, one end of the fitting 68 extending into the secondary venturi 34. A fuel emission tube 62 is fitted and supported within well 20.
A metering rod 66 is suspended within fuel well 20, having a metering end 68 formed with varying diameters. The formed end 68 is positioned within the main fuel jet orifice 69 for operation in response to engine requirements. Flow of fuel through main orifice 69 is controlled by metering rod 66 and in accordance with that portion of the formed end 68 which is positioned within opening 56.
The metering rod is accurately formed at the lower end thereof and engages the fuel orifice to permit maximum fuel efficiency. In particular, with the engine running at idle, the lower end 68 of metering rod 66 fits closely with the adjoining walls of orifice 69 thereby defining a minimum annulus defining a sufficiently large fuel passage to sustain the engine at idle. This will permit satisfactory engine operation without over-enrichment of the fuel mixture, a condition that promotes excessive production of unburned hydrocarbons.
Referring to FIGURES 3 to 7, fuel well 20 includes a relatively narrow elongated channel formed substantially uprightly in the carburetor wall and opening at the upper end into an enlarged bore 48 along an outwardly tapered surface 49. A peripheral shoulder 51 formed on tapered surface 49 provides a rigid annular seat for flexible dia phragm 52 which is displaceable to inner and outer positions. Metering rod 66 includes an elongated central shank having a tapered portion 68 at one end thereof and an engaging head 53 at the other. Said engaging head 53 includes a peripheral shoulder 54 adjacent to a hub 59. Head 53 terminates at its upper end in an enlarged annular projection 61 having opposed conical seating surfaces 63 and 64 at the ends thereof, seating surface 64 being connected to hub 59 along a peripheral slide surface '67.
Metering rod 66 is connected at the head end 53 to a coupling 71 having a washer 72 at the upper end and a shoulder 73 spaced from the washer. A bifurcated oscillating end 74 of the throttle lever 76 is urged by a spring 77 into engagement with upper washer 72, thereby providing a resilient yieldable connection between coupling 71 and the throttle lever 76, permitting a degree of throttle over-travel as lever 76 is actuated. Lever 76 is pivotally mounted to the carburetor body and connected to the throttle shaft or to a suitable linkage associated with the throttle shaft and with the accelerating pedal.
Metering rod 66 and coupling 71 are carried in an assembly including the flexible diaphragm 52 formed of rubber, fabric or the like supported against shoulder 49 and held centrally by hub 59 and a cup member 78 being urged against the diaphragm 52 by a spring 79. The peripheral edge of diaphragm 52 is carried on annular shoulder 49 and maintained in place by the upturned lip 81 of the spring retainer 82 which surrounds a portion of coupling 71 and includes one or more peripheral openings 83.
A thin walled guide member 84 carried in enlarged bore 48, includes a peripheral rim 86 positioning said member, and a cap 87 urging said rim 86 into engagement with the walls of bore 48, holding member 84 in place. Guide 84 includes a cylindrical center portion or guide tube 88 defining a slide surface for coupling 71 as the latter is reciprocated in response to movement of throttle lever 76, and to fiexure of diaphragm 52. Cylindrical portion 88 of said guide member 84 locates com pression spring 79 along its outer surface. A seal ring 100 is retained in the groove in the periphery of member 71 and slidably contacts walls of the guide member center portion 88 to form a sliding fluid tight seal.
To achieve the necessary limited free movement between metering rod 66 and coupling 71, the latter is provided with an axial bore 70 having a diameter approximating, yet smaller than the diameter of projection 61. To permit ease of assembly of members 61 to 71, and also to facilitate replacement of metering rod 66 as needed, coupling 71 locking end is so formed to define a spring type locking socket 65. As presently shown, particularly in FIGURES 3 and 8, socket 65 wall is weakened by one or more longitudinal slots 19 and 23 to define a plurality of segments 89 therebetween. An inturned lip 92 or similar protuberance extending radially inwardly from each segment 89, forms a limiting means against which surface 64 may abut, thereby limiting longitudinal movement of metering rod 66.
For assembling coupling 71 to metering rod head 53, segments 89 may be sprung apart when coupling 71 is removed from the close fitting walls of cylindrical portion 88. In such position, shoulder 73 of coupling 71 will come to rest on the upper surface of retainer 84. Longitudinal slots 19 and 23 formed in the lower half of coupling 71 will then extend downwardly beneath the lower rim of cylindrical portion 88 thus permitting the respective segments 89 to be forced apart sufiiciently to open bore 70 and permit entry of the head projection 61. Segments 89 are then returned to their closed position with the inturned lip 92 overlying projection 61 so that metering rod 66 is in effect movably and slidably retained within the coupling 71. The coupling and metering rod are then drawn together up into the guide portion 88 of guide member 84.
Referring to FIGURE 4, plenum chamber defined by the respective diaphragm 52 and guide member 84 is connected to a source of vacuum at the engine intake manifold M. This is achieved by a passage 92 formed in a wall of mixing conduit 12 at a position below the carburetor throttle valve 22. Passage 92' is communicated through an elongated passage 95 to a cross boring 94 which terminates in the plenum chamber 95. Plenum 95 may also be communicated to intake manifold M at any of several locations other than in the carburetor itself.
Referring to FIGURES 3, 5, 6, and 7, the relative position of the coupling member 71 and metering rod 66 are shown during various phases of engine operation. In FIG- URE 3, the engine is illustrated at rest with no appreciable vacuum being drawn in the intake manifold M and consequently no vacuum being drawn on plenum 95. Thus, with throttle 22 in the closed position, coupling 71 will be withdrawn upwardly to a maximum position by throttle lever 76 which is connected to the throttle actuating means. Seating surface 64 of projection 61 will thus be supported on the upper edge of lip 92 thereby lifting metering pin 66 to position the widest part 45 of end 68 in nozzle opening 69. Diaphragm 52 is in a partially withdrawn position since there is no vacuum condition within plenum 95 and since compression spring 89 is of sufiicient strength to overcome the upward pull of the throttle lever 76, which spring would otherwise urge the diaphragm toward the downward position.
At cranking or start up of the engine, a maximum vacuum of about .19 inch of water is drawn at intake manifold M thereby immediately evacuating plenum 95 while maintaining the position of the coupling 71 substantially as shown in FIGURE 3. This pre-supposes that the engine is started in the normal manner with the throttle I substantially closed or cracked. Thus, diaphragm 52 will be drawn into plenum 95 and thereby bringing the inner surface of cup 78 into engagement with the lower surface of the guide portion 88. In thisposition diaphragm 52 is withdrawn to its maximum upward position and metering rod 66 is so disposed as to permit the lower end 68 to locate the portion 45 for the proper engine idle position.
With the engine running at open throttle, as shown in FIGURE 6, coupling 71 is depressed partially into guide portion 88 by the throttle lever 76. The upper seating surface 63 of projection 61 will be in abutting engagement with the end wall of the socket 65 formed in the lower part of the coupling 71 thereby urging the metering rod 66 downwardly thereby positioning a narrower portion 55 of the rod in metering orifice 69. At part throttle, the manifold vacuum will substantially drop off thereby lessening the vacuum created in the plenum 95. With the decrease in vacuum, diaphragm 52 will be unable to resist the position urging of the coupling 61 by lever 76 to force the metering rod 66 into its normal running position.
FIGURE 7 illustrates the position of the throttle lever 76 and coupling 71 with the metering rod depressed to its maximum position. Thus, shoulder 97 will abut the hub 98 thereby precluding further downward movement of the metering rod 66. Any further depression of the throttle lever 76 will result not in the movement of the coupling 71 to further displace the metering rod 66, but rather in spring 77 being further depressed until the throttle lever 76 has reached its point of maximum depression.
Illustrative of the preferred operation of the invention, again referring to FIGURES 3 and 5, at engine start-up a maximum vacuum will be created in inlet manifold M, which is communicated to plenum 95. There is thus a tendency to withdraw metering rod 66 upwardly through orifice 69 in response to movement of the diaphragm 52. However, engagement of the projection 61 against lip 92 of coupling 71 will locate metering rod 66 in accordance with a desired predetermined position by abutment of the cup against the lower edge of guide portion 88.
During engine idle, the throttle will gradually be cracked to increase the speed of the engine. As this happens, the vacuum in plenum 95 decreases substantially thereby permitting diaphragm 52 to be urged by spring 79 from the plenum.
This idle position is such that the annulus opening defined by metering rod end 68 and orifice 69, affords an optimum rate of fuel flow to maintain the engine at idle speed.
Thereafter, as manifold vacuum decreases, spring 79 will overcome in part the decreased vacuum in plenum 95 and urge diaphragm 52 downwardly thereby lowering metering rod 66 to define a larger opening at orifice 69 and allow a greater fuel flow. As the engine is subjected to a greater load, the resulting decrease in manifold vacuum will permit rod 66 to adjust itself automatically downwardly and provide a richer air fuel mixture without a comparable adjustment in the throttle or throttle actuating means.
This automatic adjustment in rod 66 is limited by freedom of movement of projection 61 in socket 65 which allows diaphragm 52 entire control regarding the positioning of projection 61.
It is clear from the foregoing that the carburetor presently described affords several advantages heretofore unrealized in the art. For one thing, a more accurate metering of fuel to the discharge nozzle assures a more economical utilization of the fuel energy. Further, and by no means secondarily in importance, is the minimization or complete elimination of undesirable emission which 6 would tend to aggravate a smog problem. Also, the novel arrangement permits automatic adjustment of the carburetor air fuel mixture calibration in immediate response to a particular engine demand or requirement such as a minor load imposed on the engine.
In the latter instance, the metering rod is normally adjusted by actuation of the throttle. However, when the engine encounters a road condition which would tend to impose an added load, the instantaneous decrease in intake manifold pressure is transmitted to the air motor thereby causing the latter to override control by the throttle and permit the metering rod to freely adjust and cause a richer air-fuel mixture to be delivered to the engine. The richer mixture will of course prevail until such time as the engine power adjusts to the road load, thereby automatically initiating a change in intake manifold vacuum, which in turn repositions the metering rod to its original location to be controlled by the throttle.
It is appreciated that the foregoing description is designed for application to a variety of carburetor structures. It is therefore seen that the unique arrangement can be modified and changed without departing from the spirit and scope of the invention.
1. In a carburetor for an internal combustion engine including a body, a mixture conduit formed in the body, a throttle valve having a shaft journalled in the mixture conduit and being operable to regulate passage of air fuel mixture therethrough, an actuating mechanism connected to said throttle, a fuel bowl formed in said body holding a supply of fuel, a ventiuri in said body including a nozzle, a fuel duct carrying a fuel stream from said fuel bowl to said nozzle for injection into said mixture conduit, a metering orifice in said fuel duct adapted to regulate said fuel stream, an air motor associated with said carburetor and connected to a source of varying vacuum in said engine, said air motor having a displaceable diaphragm at one wall thereof, and being moveable between inner and outer positions in response to variations in said vacuum source, a metering rod having opposed ends including a tapered end disposed in said metering orifice and having the other end engaging said diaphragm to be reciprocably moved between said inner and outer positions in said orifice in response to a pressure change in said air motor, a lost motion connection operably engaging said throttle actuating mechanism with said metering rod and includ- 111g;
(1) an elongated coupling member (71) extending coaxially of said metering rod and engaging said throttle actuating mechanism,
(a) a cavity formed in the end of said elongated coupling member and extending coaxially thereof,
(b) said metering rod including a projection at the end thereof opposite to said metering end, said cavity includes an opening defined by an inwardly projecting lip (92) supporting said metering rod, the wall of said cavity being slotted to provide segments and permit lateral displacement thereof whereby said opening will 1 be sufiiciently enlarged to receive said projection thereby loosely retaining the latter in said cavity when said segments are returned to an undisplaced position, said projection being loosely received in said cavity to permit limited movement of said rod with respect to said coupling member,
whereby said metering rod is adjustable for regulating the position thereof with respect to said orifice in immediate response to variations in the degree of vacuum in said engine, independent of the throttle position.
2. In a carburetor as defined in claim 1 including a guide member carried in said air motor and spaced from said diaphragm to define a plenum chamber, said guide member including a guide tube extending co-axial of said metering rod, and said coupling being slidably received in said guide tube.
3. In a carburetor as defined in claim 2 including resilient seal ring (100) forming a sliding fluid tight seal between said guide tube and said coupling member.
4. In a carburetor as defined in claim 1, wherein said projection (61) on said metering rod includes;
(a) a slide surface (67) registered in said opening, and an enlarged portion having a diameter greater than said opening to permit retention of said projection in said cavity.
References Cited UNITED STATES PATENTS Kemp 26l-69 Baker 26151 Jones 26151 X Moseley.
Moseley et a1. 261-51 Carlson et a1. 261-69 X Read 26151 Powell et a1 26169 X Kalert et a1. 261-69 Newman et al. 26169 15 RONALD R. WEAVER, Primary Examiner.