US3057606A

US3057606A - Carburetor

Info

Publication number: US3057606A
Application number: US19017A
Authority: US
Inventors: Hegna Hans Olav
Original assignee: California Research LLC
Current assignee: California Research LLC
Priority date: 1960-03-31
Filing date: 1960-03-31
Publication date: 1962-10-09
Anticipated expiration: 1979-10-09

Description

H. O. HEGNA Oct. 9, 1962 CARBURETOR Filed March 3l, 1960 FIG.1O

INVENTOR N .z

0L, HEGNA Aromvs United tates Patent 3,057,606 CARBURETOR Hans Olav Hegna, Sausalito, Calif., assignor to California Research Corporation, San Francisco, Calif., a corporation of Delaware Filed Mar. 31, 1960, Ser. No. 19,017 2 Claims. (Cl. 261-65) This invention relates to carburetors for internal combustion engines and more particularly to a novel throttle Valve for alleviating some of the difliculties encountered under climatic conditions which cause icing in the carburetor.

In cool, humid weather the evaporation of a volatile fuel from the air-fuel mixture passing through the carburetor drops the temperature of the mixture below the freezing point of the entrained water vapor. Under these conditions, the water vapor condenses out of the air and forms icy deposits on the chilled internal portions of the carburetor. Of primary interest to the present invention are those icy deposits which build up on the throttle valve and cause the engine to malfunction or stall during the warming-up period.

Experience in cold-weather driving of automobiles under icy conditions has shown an inclination of the engine to stall if it is placed in an idling condition during the warm-up period. Thus, the engine may falter or stall when traffic conditions require that the automobile be brought to a stop. The constant restarting of the engine, which may in itself 'oe difficult, creates a situation which is at least inconvenient for the driver and which is not conducive to the desirable steady iiow of traiiic.

A principal object of this invention is to provide a i novel throttle valve for a carburetor, which throttle valve will reduce the tendency of an engine to malfunction when operated under conditions which cause icy deposits .to form in the carburetor.

Another object of this invention is to provide a carburetor which will function to reduce the tendencyof an engine to stall during the warm-up period while operated under varying loads in cold weather.

Other objects of this invention will become apparent as the description of it proceeds hereinafter, in conjunction with the accompanying drawings in which:

FIG. l illustrates in side elevation and partly in section a carburetor in which this invention is incorporated.

FIG. 2 is a plan view of a throttle valve made in accordance to this invention.

FIG. 3 is a View in side elevation and partly in section taken along the line 3-3 of FIG. 2.

FIG. 4 is a view in side elevation and partly in section of a modification of a throttle valve made in accordance with this invention.

FIGS. 5, 7 and 9 illustrate in plan view three other, different modifications of throttle valves embodying this invention, and the corresponding FIGS. 6, 8 and l0, which are taken respectively along the line 6-6 of FIG. 5, the line 8-8 of FIG. 7, and the line 10-10 of FIG. 9, illustrate transverse sections of the corresponding modiiications of throttle valves embodying this invention.

FIG. l illustrates an exemplary carburetor 20 in which the throttle valve of this invention has been installed. As will be appreciated in the art, in a carburetor of the type illustrated air is drawn into the carburetor through the air horn 22 and iiows past the open choke valve 24 and through the auxiliary Venturi tube 26 and the main Venturi passage 2S and thence through the mixture conduit 30. When the throttle valve 32 is open, the air flows through the auxiliary Venturi tube with sufficient velocity to reduce the pressure at the opening 34, within y the throat of the auxiliary Venturi tube, of the main discharge jet 36. The reduced pressure causes fuel to flow from the iioat chamber 38, which is vented through the vent tube 40 to the air entering the carburetor, and through the main discharge jet and into the air stream passing through the auxiliary Venturi tube. The fuel is entrained in the air, and as the mixture iiows toward the mixture conduit 30 it merges with the air owing through the main Venturi passage to achieve the desired ratio of fuel to air necessary for the proper operation of the engine to which the carburetor is attached.

The throttle valve 32 is a plate pivotally mounted within and set transversely across the mixture conduit. The valve can be rotated by a linkage outside of the carburetor body to control the opening of the mixture conduit from a position of the throttle valve where the conduit is substantially closed to the passage of air through it, as indicated by the solid line drawing of the throttle valve in FIG. 1, to a position where the mixture conduit is substantially fully open for the passage of the mixture through it, as indicated by the dotted line drawing of the throttle valve 32 in FIG. l. When the throttle valve is open, the mixture of fuel and air passes from the carburetor into the intake system of the engine. When the throttle valve is closed, the volume of air passing through the carburetor is at a minimum, and the velocity of the air through the auxiliary Venturi tube is too low to produce sufficient reduction of pressure within the throat of the auxiliary Venturi tube to cause fuel to flow from the main discharge jet.

When the throttle valve is in the closed, or idle, position, the operation of the engine causes the pressure to be reduced in the portion 42 of the mixture conduit below the throttle valve. The air in the upper portion of the carburetor is at substantially atmospheric pressure, and this pressure, acting through the idle-air bleed or bypass 44 and through the idle tube 46, forces fuel through the idle port 48 into the mixture conduit below the throttle valve. 'Ihe secondary idle air bleed 50 assists this operation. Some air is entrained with the fuel ejected from the idle port, and additional air iiows through a small clearance 52 between the throttle valve periphery and the inner wall of the mixture conduit to form the proper air-fuel ratio for operation of the idling engine.

A second idle port 54 opens just above the throttle valve. When the throttle valve is slightly rotated from its closed position, the air passing around its periphery reduces the pressure at the second idle port, and fuel flows from the latter in addition to the fuel flowing from the first idle port 48 to maintain the proper ratio of fuel in the increased volume of air. When the throttle valve is opened still more, the increased air flow through the carburetor balances the pressures between the idle air bleed and the idle discharge ports, and fuel ceases to flow from the latter. At the same time, the iiow of air through the auxiliary Venturi tube increases sufficiently to cause fuel to be discharged from the main discharge jet in the proper air-fuel ratio for the desired engine operation.

In certain cold-weather conditions malfunctioning of the carburetor is experienced, caused by icy deposits formed on the internal parts of the carburetor. It has been determined that these icy deposits form most readily on cool days of relatively high humidity, and they have been experienced in a range of ambient temperatures from about 25 F. to about 60 F. when the relative humidity was above about 60%, the icing condition increasing in severity as the relative humidity increased. The temperature range between 30 F. and 50 F. appears to be especially critical for icing conditions. In a series of tests made on automobiles to determine the conditions which would cause carburetor malfunctioning due to icing, it was found that at an ambient temperature of 40 F. with 100% relative humidity, 43% of the test cars experienced stalling one or more times during the warming-up period.

Insofar as carburetor operation is concerned, icy deposits are particularly critical when they build up in the Venturi passages and on the throttle valve. Icing of the throttle valve produces erratic and uneven operation of the engine and stalling, particularly when the engine is placed in an idling condition during the period it is warming up. A suggested cause for this malfunctioning is that the ice deposited on the throttle valve while the engine is running with the throttle valve open tends to melt olf of the surface of the valve when the latter is placed in the idle position where it is no longer cooled by large volumes of refrigerated air passing over it. The throttle valve picks up heat from the engine, and the ice adhering to it melts at the surface of the valve, producing a lm of water upon which the icy particles above the surface layer oat. The icy deposit then will slide toward the lowest side of the throttle valve and block the small air passage between the periphery of the throttle valve and the inner wall of the mixture conduit, thus cutting off a large portion of the relatively small amount of air which flows around the throttle valve in the idle position. In some cases, the icy particles which bridge the peripheral clearance between the throttle and the wall of the mixture conduit apparently refreeze together, caused perhaps either by coming into contact with the cold Wall of the body of the carburetor or by being more directly exposed to the stream of cold air which is attempting to flow through this clearance.

The throttle valve is normally set to have a clearance in the range of about ve-thousandths to about fivehundredths of an inch between its periphery and the adjacent wall of the mixture conduit when it is in an idle position, the clearance depending upon the construction of the particular carburetor, to provide the proper amount of air to mix `with the fuel issuing from the idle port for the operation of the idling engine. In the idle position, the amount of air flowing past the throttle valve does not appreciably affect the amount of fuel issuing `from the idle port, the latter remaining substantially constant. Hence, when an appreciable portion of this air supply is cut oli", the ratio of air to fuel in the mixture Agoing to the engine is changed drastically, and the engine no longer operates properly.

The present invention improves appreciably the operation of an engine during the warming-up period. It provides a means for preventing icy deposits from sliding off the surface of the throttle valve and blocking the air passage around the periphery of this valve when it is in the idle position.

FIGS. 2 and 3 illustrate a preferred embodiment of a throttle valve made in accordance with this invention. In this instance the valve comprises a circular thin plate or disk 56 which is affixed by the screws 58 to a shaft 60. The shaft may be mounted transversely across and within the mixture conduit of the carburetor in a manner to permit the valve to be rotated from a closed or idle position to an open or running position. Normally in the type of carburetor illustrated, when the throttle valve is in the closed position it will be tilted at an angle to the horizontal in a direction transverse to the axis of t-he shaft 60, as shown by the position of the valve 32 in FIG. l. The disk 56 is formed with, or has securely affixed to it, an upwardly projecting rim portion 62 which extends throughout approximately one-half of its periphery on the portion of the disk which will be in the lowermost position when the valve is installed in an operating carburetor. The rim portion has a small gap 64 formed through it at its mid point to permit water produced from the ice melting on the surface of the valve to drain away. The rim 62 prevents icy deposits from sliding over the edge 66 of this peripheral portion of the `disk and blocking the air passage 52 between it and the wall of the mixture conduit. The gap 64 prevents suicient water from accumulating to oat the icy deposits over the top of the rim 62 and blocking this air passage.

A throttle valve made in accordance with the illustrations of FIGS. 2 and 3 was installed in a carburetor on an engine which was operated in alternate cycles of l5 seconds idle at 800 r.p.m. and l5 seconds running at 2300 r.p.m. continuously for 30 minutes. rI`he cycling operation was done automatically by mechanical means to maintain uniform 15-second intervals and to insure a uniformly repetitive engine control for each consecutive condition. The air fed to the carburetor had a temperature of 45 F. and a relative humidity of An icing condition occurred in the carburetor.

The total number of revolutions made by the engine during the idling cycles only was used as a gauge of dependability of engine operation during the period, since this would reect not only stalling but also faltering or slowing-down of the engine or other malfunctioning which did not result in a complete stall. When the engine stalled in a l5second id'ing period, it was started automatically by the cycling mechanism at the beginning of the next consecutive running cycle.

The throttle valve of this invention was tested under the same operating conditions against the standard flatdisk throttle valve supplied with the carburetor being used, each throttle valve being used in the same carburetor on the same engine for the different tests. With the throttle valve of the present invention, the engine accumulated 9,952 total revolutions during the id'ing periods of a 30-minute run, while with the standard throttle valve supplied with the carburetor the engine accumulated a total of 3,788 revolutions during this period. The operation of the engine under the stated test conlitions was not entirely trouble free during the idling cycles when the throttle valve of this invention was used in the carburetor. However, its operation was very detinitely improved over that which obtained when the stendard throttle valve was used. Separate, similar tests substantiated the beneficial effect of the throttle valve of this invention.

FIG. 4 illustrates in sectional view another embodiment of this invention. In this embodiment, a separate circular plate 68 is used, made with an upturned peripheral rim 70 completely around its circumference. Two diametrically

opposed gaps

72 and 74 are formed in the rim, similar to the gaps 64 of FIG. 2. The plate 68 is secured on the upper face of a standard throttle valve disk 76 by means of the screws 78 which fasten the disk to the shaft 80. This auxiliary plate funct'ons in the manner of the rim 62 described heretofore with respect to the first embodiment of the invention to restrain icy deposits from sliding over the peripheral edge of the throttle valve and blocking the small air passage between it and the wall of the mixture conduit 30 when the throttle valve is in the idle position. The plate is symmetrically formed, and hence does not require a determination as to which side of the rim belongs in the uppermost position and which in the lowermost to function properly when placed on a throttle valve of the form illustrated. The full rim functions to prevent the migration of icy deposits from the face of the throttle valve over any portion of its peripheral edge.

In the embodiment of the invention illustrated in FIGS. 5 and 6, an auxiliary member 82 of corrugated form is applied to the uppermost surface of the throtte valve disk 84. The corrugations are disposed in alignment with the axis of the shaft 86 and preferably are made with the vertically disposed faces 88 at steep angles to the plane of the upper face of the throttle valve disk. The corrugations function to prevent the icy deposits from sliding on the face of the throttle valve toward the side which is lowermost when the valve is in the idle position. It will be understood that the throttle valve disk itself may be corrugated to perform the same function as the auxliiary plate 82 performs.

In the embodiment of the invention illustrated in FIGS. 7 and 8, the disk 90 of the throttle valve plate is formed with, or has aiiixed to it, a plurality of projections 92 which extend upwardly from its surface. These projections may, for example, be pins secured in holes drilled into the plate and placed sutlciently close together to prevent icy deposits from sliding off of the surface of the plate in masses large enough to block the clearance between the throttle valve and the wall of the mixture conduit when the throttle valve is in the idle position. Alternatively, an auxiliary flat member having closely yspaced projections extending upwardly from it may be secured on the surface of the standard throttle valve plate to achieve this result.

FIGS. 9 and 10 illustrate a different embodiment of the invention. In this embodiment, a piece of at screenlike material 94 is Shaped to conform wit-h the valve plate 96 and is secured by the screws 98 to close contact with the surface of the plate exposed to icy deposits. The screen preferably is made of interwoven metal wires land with a imesh sufficiently coarse to cause the frozen water deposited from the fuel-air mixture to be trapped initially in the interstices of the Screen, which will prevent the icy deposits from sliding oi the surface of the throttle valve when the latter is in the idle position. In this embodiment of the invention, as well as in all of the other embodiments previously described, the Water formed `by the ice melting on the throttle valve is permitted to drain olf of the valve and be drawn into the intake system of the engine.

IWhen the throttle valve is open to operate the engine substantially above its idling speed, there is suflicient clearance between the periphery of the throttle valve and the inner wall of the mixture conduit to permit the icy deposits to fall, or be drawn into, the intake system of the engine without blocking the air passages necessary for proper engine operation. The ice melts, of course, in the intake system as the engine warms up, and the resultant water is converted to vapor, which is entrained in the fuel-air mixture and passes through the engine without causing the engine to malfunction.

The several embodiments of the invention described heretofore and illustrated in the drawings Present an effective means for preventing ice accumulations on the throttle valve lfrom causing malfunctioning of the engine during the idle period. It will be apparent that the invention can be embodied in other forms than those presented herein and applied to other shapes of valve plates than the disk of the exemplary embodiment without departing from the inventive concept. Therefore, it is intended that the invention embrace all equivalents within the scope of the appended claims, v

I claim:

1. In a carburetor, a conduit for entraining a mixture of fuel and air, a throttle valve in said conduit comprising a plate pivotally mounted transversely of said oonduit and rotatable from a rst position substantially but not entirely `closing said conduit to the passage of air therethrough to a second position in which said conduit is substantially opened to the passage of said mixture therethrough, ice-holding means `on a surface of said plate and `distributed over a su-btantial portion of the area of said surface to restrain ice deposited on said surface during passage of said mixture through `said conduit from sliding off said surface in pieces large enough t0 substantially completely :close off at least a portion of said conduit to the passage of air therethrough when said plate is in approximately said first posit-ion, said ice-holding means comprising corrugations on said surface, said corrugations positioned in substantially parallel alignment with the axis of rotation of said plate.

2. In a carburetor, a conduit for entraining a -mixture of fuel and air, a throttle valve in said conduit comprising 'a plate pivotally mounted transversely of said conduit and rotatable from a tirst position substantially but not entirely closing said conduit to the passage of air therethrough to a second position in which said conduit is substantially opened to the passage of said mixture therethrough, ice-holding means on a surface of said plate and distributed over a substantial portion of the area of said surface to restrain ice deposited on said surface during passage of said mixture through said conduit from sliding olf said surface in pieces large enough to `substantially completely close olf at least ya portion of said conduit to the passage of air therethrough when said plate is in approximately said first position, said ice-holding means comprising an element of screenlike material secured to said surface and in contact therewith.

References Cited in the file of this patent UNITED STATES PATENTS 1,495,696 Kinnie et al. May 27, 1924 1,633,050 T-horton June 2l, 1927 1,753,009 Hess Apr. l, 1930 1,882,966 Schaffner Oct. 18, 1932 2,328,736 Mock Sept. 7, 1943 2,393,760 Eberhardt Ian. 29, 1946 2,658,734 Henning Nov. 10, 1953 FOREIGN PATENTS 182,924 Great Britain July l2, 1922 507,977 Great Britain June 23, 1939