US2658733A - Accelerating pump control fob - Google Patents

Description

Nov. 10, 1953 H. A. BOLLER 2,658,733

ACCE/ILERATING PUMP CONTROL FOR CARBURETORS Filed Nov. 6, 1950 JNVENTOR.

HENRY A. BOLLER F|G.2. BY

d'V/a I AJILQBNE Patented Nov. 10, 1953 ACCELERATING PUMP CONTROL FOR CARBURETORS Henry A. Boller, Pontiac, Mich., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application November 6, 1950, Serial No. 194,289

2 Claims.

This invention relates to carburetors for internal combustion engines, particularly of the automotive type, and consists in novel means for controlling the action of a suction operated adjunct toinsure prompt, but modulated, engine response.

Internal combustion engine carburetors of the automotive type are usually provided with accelerating pumps for the purpose of supplying an extra charge of fuel during acceleration. The form of accelerating pump, as shown in a copending application, Serial No. 117,772, filed September 26, 19%9, now Patent No. 2,619,333, issued November 25, 1952, in the name of John S.

Carrey, has a pumping diaphragm and meter ing pin operated jointly by a spring connection to the throttle valve and by changes in manifold depression applied thereto. This pump provides an eccelerating charge either when the throttle valve is opened or the manifold depression drops. Where the diaphragm is exposed to the full manifold depression, which may be as high as 18" Hg during idling, the time interval required for dissipation of the low pressure in the pump suction chamber, upon rapid, initial opening movement of the throttle valve, is such that the mentioned spring connection i substantially compressed by throttle movement, before appreciable pumping action occurs. This results in delayed, but sharp pump action and corresponding hard or rough feel of the engine in accelerating.

Another disadvantage which exists when the pump suction chamber is exposed to full manifold depression, is that when the engine is operated at high altitudes, the effective depression decreases (at the rate of about 1" of mercury for each 1000 feet of altitude) so that the pump which operates fairly satisfactorily at sea level when the manifold depression varies from 18 of mercury to a few inches of water, will not operate satisfactorily at 10,000 feet of altitude.

This harmful effect is accentuated by erratic action of the fuel metering or step-up valve, also controlled, in part, by engine suction. Obviously, where such suction control is calibrated to provide a particular lean fuel mixture at, say,

a manifold depression of 12" of mercury, as

exists during part throttle operation, .a considerably richer mixture will be supplied when the engine is operated at high altitude because of the reduced manifold depression available. A further complication results at high altitudes due to the reduced air component in the mixture.

My solution of the above problems, as disclosed but not mentioned or claimed in the above copending application, consists in providing an air bleed connection between the pump suction chamber and the carburetor mixture passage anterior to the throttle valve. This feature serves admirably to expedite and soften the initial pumping action and also very substantially moderates the wide difference in depressions which would be applied, otherwise, to the pump and metering pin controls at sea level and at high altitudes.

Consequently, the main object of the present invention is to provide means for avoiding the mentioned difficulties inherent in ordinary suction controlled accelerating pumps and metering valve devices. This object and other more detailed objects are attained by the device illustrated in the accompanying drawing in which:

Fig. 1 is a vertical, sectional view of a carburetor incorporating my invention and shown at idling position.

Fig. 2 is a similar view, but showing the throttle initially opened during operation.

Fig. 3 is a fragmentary, vertical sectional view of the carburetor showing the throttle in the same position as in Fig. 2, but with the pump diaphragm moved upwardly by its operating spring.

Fig, 4 is a detailed, substantially enlarged and partially sectionalized, view of the pump operating means.

Fig. 5 is a sectional detail showing the main fuel metering orifice and metering pin.

In the drawings, the carburetor H! has a downdraft mixture conduit ll provided with multiple Venturi tubes I2 therein. The mixture conduit has a flange Ha at its lower extremity for attachment to the engine intake manifold (not shown). Fuel is supplied to the smallest Venturi tube from a constant level fuel chamber i3 through the usual metering orifice I l controlled by metering rod Ma and a main nozzle [5 and an idling fuel system [5a, as more fully shown in the above-mentioned copending application. A butterfly throttle valve [6 controls the discharge of mixture to the intake manifold and the admission of air to the mixture conduit is regulated by a choke valve I"! which may have any suitable manual or automatic control.

For providing additional increments of fuel to the mixture conduit during acceleration, an accelerating pump is provided in the constant level chamber l3. The accelerating pump comprises a suction chamber I 8, formed in the bottom wall of chamber 13, a flexible diaphragm l9 of synthetic rubber or other gasoline resistant material sealingly covering chamber 18, and a dome-shaped member 20 having a vertical, tubular extension 2|. Member 20 sealingly engages the peripheral upper surface of diaphragm ill to form a pumping chamber 22. An inlet port 23 is provided in dome-shaped member 23 for the admission of fuel to the pump chamber from the constant level chamber. Pump outlet port 24 communicates with mixture conduit H through a passage 25 having an outlet check 26 and a restricted pump discharge nozzle 21.

Changes in manifold depression are 'transmitted to pump suction chamber [8 through suction passage 29, 30, having a restriction 3| and communicating with the mixture conduit posterior to throttle Ni. A restricted bleed passage 32 connects the suction passage with the mixture passage posterior to the Venturi tubes, but anterior to the throttle valve.

For rendering diaphragm l9 also responsive to throttle opening movements, a stem 33 is secured at its lower end to the diaphragm and is closely received and slidable in tubular extension 2|. A coil spring 35, received on the tubular extension, acts through a washer 36 abutting a stem shoulder 3'! to normally urge stem 33 and diaphragm l9 upwardly toward their rest positions, as indicated in Fig. 4. A goose-neck link 38 is slidably received in a guideway I9 in the carburetor wall structure and is connected at its lower extremity by means of a link 3811 to a crank |6a rigid with the throttle valve. A horizontal extension 40 on link 38 has an aperture 42, through which a larger portion of stem 33 loosely projects, and normally abuts the upper surface of washer 36 to limit upward or discharge movement of the stem and diaphragm relative to the goose-neck link and throttle valve under the influence of spring 35.

A horizontal tab 43 is slidable on the reduced, upper extremity of the pump stem and is normally urged against an upwardly facing shoulder 45 on the stem by a coiled spring 46. As the throttle moves toward open position, i. e. from the position of Fig. 1 to that of Fig. 2, link extension 40 moves upwardly whereupon force is applied to the stem and diaphragm through the spring 46 and through washer 48 and shoulder 49 on the stem. Thus, movements of the pump diaphragm are responsive both to manifold depression changes and throttle movement.

Metering rod Ma is detachably mounted on a pin 50, projecting from an angular clip I, formed as a part of previously mentioned tap 43. This clip is slidably lodged between the upper, transverse arm of goose-neck link 38 and a lug 52 projecting from link extension 40 opposite this upper arm of the link. Thus, the metering rod and its carrier clip 5|, in general, move with the pump stem. A small spring 53 urges the metering rod against one side of the metering rod jet, as disclosed in Ewart Patent No. 1,961,747.

Operation of the device is as follows:

When the engine is idling and the throttle is closed, intake manifold depression, as measured by a U-tube, mercury manometer, is in the order of 18 Hg. This depression is transmitted to the pump suction chamber through passage 29, 30 and, except for bleed passage 32, the same depression would be applied directly to the pumping diaphragm. During idling, the diaphragm is drawn to its lowest position, as in Fig. 1, so as to fully charge pump chamber 22 and maintain metering rod [4a in its lowest and, usually, most restricting position within fuel metering orifice l4. Upon opening movement of the throttle to accelerate the engine, the depression in the intake manifold drops sharply as does, likewise, the depression in suction chamber l8. Spring 35 expands and the diaphragm moves upwardly causing a discharge of accelerating fuel into the manifold.

If the'bleed passage 32 were omitted, there would be, necessarily, a. substantial time interval for reduction of the pump suction chamber depression, with the result that throttle link extension 40 would compress spring 46 to a substantial degree before pumping action could occur. This would result, first in a delay in response of the engine to accelerating action of the throttle valve and, secondly, in a bump due to the combined actions of springs 47 and 35 in producing delayed and excessive pump discharge. For this reason, simple, suction responsive accelerating pumps have not been wholly satisfactory in automotive carburetors.

The provision of restricted air bleed 32 and suction passage restriction 31 substantially eradicates this difficulty by very substantially reducing the depression in the pump suction chamber during idling, so that the time interval required to reduce this depression sufiiciently for pump response becomes unappreciable and the degree of compression of spring 46 and consequent rate of ultimate reaction is likewise geratly reduced.

Air bleed passage 32 serves, in efiect, to moderate the differences in pressures which exist between the atmosphere and the pump suction chamber to a degree proportional to the reduction in atmospheric pressure which is applied to the upper face of the pump diaphragm and to the carburetor nozzles. Since a greater reduction occurs in the atmospheric pressure than in the absolute pressure in the intake manifold, as between sea level and high altitude operation, and the air bleed becomes less effective at higher altitudes, it will be seen that the net efiect is in the direction of uniformity in suction chamber depression. In other words, the effectiveness of the air bleed decreases at the same time that the effective depression available for operating the pump diaphragm decreases. Thus, one important advantage of my invention is the prompt, moderate, initial accelerating pump action and consequent sensitive, yet soft response of the engine.

The second important advantage lies in the practical elimination of the necessity of providing special pump and step operating springs for high altitude operation. I have found that by proper adjustments of the effective sizes of restricted passages 3| and 32, the change in depression under like conditions of engine speed and load, as between operation at sea level and, say, 10,000 feet altitude, is so moderated and the operation of the pump and metering rod made so nearly uniform, as to avoid the necessity of providing the usual lighter spring.

The invention may be modified in various respects as will occur to those skilled in the art and the exclusive use of all modifications as come within the scope of the appended claims is contemplated.

I claim:

1. In a carburetor, an induction conduit having a throttle, a fuel bowl for supplying fuel to said conduit, a fuel metering valve in said bowl, alternative devices for operating said valve in one direction comprising a first device responsive to pressure, including a suction chamber, an actuator in said suction chamber, a lost motion connection between said actuator and said valve, and a spring normally urging said metering valve in a direction opposing the effect of suction on said actuator, and a second device responsive to throttle opening including a positive acting connection between said throttle and said valve, said first device also including a means for operating said valve in the opposite direction comprising a resilient connection between said actuator and said valve acting to resist movement of said valve by said second device when opposed by said first device, whereby said valve may be positioned by said second device independent of said first device, means for increasing or decreasing the efiectiveness of said resilient connection on valve displacement in response to throttle opening comprising a connection between said suction chamber and said conduit posterior to said throttle, and an atmospheric bleed extending from said connection to said conduit anterior of said throttle.

2. In a carburetor, an induction conduit having a throttle, a fuel bowl for supplying fuel to said conduit, a fuel metering valve in said bowl, alternative devices for operating said valve in one direction comprising a first device responsive to pressure including a suction chamber, a combined actuator element and accelerating pump in said suction chamber, a lost motion connection between said element and said valve, and a spring normally urging said metering valve in a direction opposing the effect of suction on said actuator, and a second device responsive to throttle opening including a positive acting connection between said throttle and said valve, said first device also including means for operating said valve in the opposite direction comprising a resilient connection between said actuator and said valve to resist movement of said valve by said second device when opposed by said first device, whereby said valve may be positioned by said second device against said resilient connection independent of operation of said accelerating pump, means for increasing or decreasing the effectiveness of said resilient connection on valve displacement in response to throttle opening comprising a connection between said suction chamber and said conduit posterior to said throttle and an atmospheric bleed extending from said connection to said conduit anterior of said throttle.

HENRY A. BOLLER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,186,480 Ensign Jan. 9, 1940 2,407,535 Carlson et a1 Sept. 10, 1940 2,504,651 Clanahan Apr. 18, 1950

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