US2619333A - Carburetor - Google Patents

Description

J. S. CARREY Nov. 25, 1952 CARBURETOR Filed Sept. 26, 1949 TIM mE N E WA .s.

w o Y I 6 n B ATTORNEY Patented Nov. 25, 1952 CARBURETOR John S. Carrey, St. Louis, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application September 26, 1949, Serial No. 117,772

7 Claims.

This invention relates to carburetors for internal combustion engines, and consists particularly in a novel accelerating pump and fuel meterin means. This application is a continuation in part of my co-pending application, Serial No. 674,876, filed June 6, 1946, now abandoned. Certain features disclosed, but not claimed herein, are claimed in a copending application, Serial No. 194,289, filed November 6, 1950 in the name of Henry Boller.

Automotive carburetors arev usually provided with accelerating pumps, the purpose of which is to supply an extra charge of fuel when needed, as for acceleration. Such pumps are usually operated by the throttle or bymanifold suction. Each type has advantages and disadvantages, the throttle actuated pump having desirable positive action not attained by the suction type, whereas the suction actuated pump is capable of supplying a pick-up or accelerating charge whenever needed, even though the throttle valve is not moved. It has been found that a diaphragm type pump is more satisfactory than the piston type, since an imperfect piston packing may result in loss of pressure or sticking of the piston but the diaphragm pump arrangements with which I am familiar other than the one disclosed in mycopending application, Serial No. 674,876, have not provided for joint suction and manual operation of the same diaphragm by means of simple compact mechanism wholly concealed within and protected by the normal wall structure of the carburetor.

An object of this invention is to providean improved arrangement whereby the operation of the accelerating pump and metering pin are controlled either by the throttle valve or by changes in suction, yet providing for a greater degree of flexibility in the interrelation of movement between these elements, thereby to make their operation more nearly responsive to engine fuel requirements.

More specifically, the object of this invention is to provide, in a pump of the character mentioned, means whereby the throttle may be opened and the metering pin elevated without necessarily causing a discharge movement of the pump diaphragm until the manifold vacuum has been sufficiently reduced to justify a discharge movement.

Other objects and advantages of thepresent invention will appear readily from the disclosure which follows, where read in connection with the accompanying drawings, in which:

Fig. 1 is a side view and vertical section 2 through an automotive carburetor, embodying one form of the invention, the parts being shown in idling positions.

Figs. 2 and 3 are detailed vertical sections taken at different angles to the plane of Fig. 1 so as to illustrate, respectively, the accelerating pump discharge passage and the main fuel nozzle.

Fig. 4 is a side view of a vertical section through an automotive carburetor, embodying a modification of the invention.

Figs. 5 and 6- are fragmentary side views and vertical sections showing the pump structure of Fig. 4 in different operative positions.

Figs. 7 and 8 are, respectively, a plan view and an elevation of the operating link detail.

Referring first to Figs. 1 to 3, the carburetor l9 includes a mixtur conduit ll formed with a series of Venturi tubes l2, centrally supported in the conduit by a rib l3. Discharge of fuel mixture from conduit II is controlled by a throttle valve 14 mounted on a shaft I5. A suitable choke valve (not shown) may be provided in the upper portion of the mixture conduit. Mixture conduit II is flanged at its lower end, as at It for attachment to the engine intake manifold (not shown). A constant level fuel bowl I! encloses a float l8 controlling a needle valve (not shown) for maintaining fuel at a constant level X-X.

A metering orifice element 2| controlled by a stepped metering pin 22 is provided in the lower portion of bowl ll. Passages 23 and 24 connect element 2| to main fuel nozzle 25 which discharges into the smallest Venturi tube l2, Fuel for idlingis supplied through passages 26 and 27 to ports 28 adjacent and posterior to the edge of throttle I4 when closed.

A cavity 3! is formed in the lower wall of constant level chamber I7 and is closed on its outer side by a flexible diaphragm member 3'2, secured in place by a cap 33; Cavity 3i and diaphragm member 32 form a pumping chamber which is connected to the fuel bowl ll by inlet passage 34 controlled by inlet check valve 35. A passage 39, controlled by outlet check valve 37, and restricted outlet nozzle 38 connect the pumping chamber to mixture conduit II.

A tubular guide 49 extends upwardly'into constant level chamber [7 from the centralportion of pump chamber cavity 3| and slidably receives the diaphragmactuating stem M. A bracket 42 is secured to stem 4! and carries metering pin 22 so that movements of the metering pin correspond to movements of the diaphragm. A second tubular guide 43 extends vertically into constant level bowl I! and slidably receives a link 44 having an offset portion 45 at its upper extremity with an aperture which slidably receives the upper extremity of stem 4|. A collar or washer 45 keyed or otherwise lodged on stem 4| limits upward movement of link 44 relative thereto. Link 44, at its lower extremity is connected by a small link 4'! to an arm 48 rigid with throttle shaft l5, so that upon opening movement of the throttle the diaphragm is forced upwardly to inject a charge of accelerating fuel into the mixture conduit, and the metering orifice 21 is simultaneously opened.

A coil spring 50 is compressed between the underside of diaphragm 32 and cap 33 and urges diaphragm 32 upwardly. Chamber formed between diaphragm 32 and cap 33 is connected by a suction passage 52 to a port 53 opening into the mixture conduit l l posterior to throttle l4, so that when engine suction increases, diaphragm 32 is moved downwardly, compressing spring 50, and drawing a charge of liquid fuel from constant level chamber l1 into pumping chamber 3|. Upon sufficient decrease of suction, spring 58 causes discharge movement of the diaphragm.

An adjustable limitation on the upward or discharge movement of diaphragm 32 relative to operating link 45 is provided by a stop collar 54 which is secured to stem 4| above bracket 42. Such a limitation may be necessary to obtain the desired mixture proportions under certain conditions. The stop also permits priming action of the pump in starting the engine by operation of the throttle pedal.

It should be noted that the entire pumping and metering arrangement, with the exception of the lower extremity of link 44 and its operating connection to the throttle, is located wholly within the confines of the constant level bowl. The mechanism is thus protected from dust and other foreign material and does not interfere with the symmetrical, compact appearance of the carburetor.

Operation of the device is as follows: Fuel is drawn into pumping chamber 3| by downward movement of the diaphragm to the position of Fig. 1 upon increase in manifold suction. Thereafter, the diaphragm may move upwardly to discharge fuel into the mixture conduit either upon opening movement of the throttle through linkage 44 or upon expansion of spring 58 when a drop in suction occurs and metering pin 65 moves accordingly. The liquid fuel in the pumpin chamber acting against the diaphragm provides a cushioning Ol' dashpot action against too abrupt opening movement of the metering pin and throttle. The manual and suction operations complement but do not interfere in any way with each other.

Referring now to Figs. 4 through 8, in which a modified form of the invention is illustrated, the carburetor 56 includes a mixture conduit 51 formed with Venturi tubes 58, centrally supported in the conduit. A throttle valve 68 mounted on a shaft 6| controls the discharge of fuel mixture from mixture conduit 51. A flange 52 is formed at the lower end of mixture conduit 51 for attachment to the engine intake manifold. The constant level fuel chamber 63 includes a float controlled needle valve (not shown) for maintaining fuel at a constant level.

A metering orifice element 64, controlled by a stepped metering pin 65 is positioned in the lower portion of constant level chamber 63. Passages 4 66 and 6! connect the metering orifice element with the main nozzle passage 68.

A depression 69 is formed in the bottom wall of constant level chamber 63 and is closed on its inner side by a diaphragm member 10, secured in place by an inverted cup H, the cup and diaphragm cooperating to form a pumping chamber I2 which communicates with constant level chamber 63 by means of an opening 13 in the upper portion of cup H. An annular screen 14 is mounted on cup H to filter impurities from fuel entering the pumping chamber. A passage [5 controlled by an outlet check valve 16 and having a restricted outlet nozzle 17 connects pumping chamber 12 with fuel mixture conduit 51. A tubular guide 13 extends upwardly into constant level chamber 63 from the central portion of cup 1| and slidably receives the diaphragm actuating stem 19. Stem 19 is formed with a groove which receives and prevents upward movement of a cupped, horseshoe washer 8| relative to the stem. A coiled compression spring 82 is received about guide 18, its lower end abutting a boss 83 on the upper surface of cup H and its upper end abutting washer 8| so as to tend to urge stem 19 and diaphragm 10 upwardly.

A chamber 84, formed between bowl depression 89 and diaphragm 10 is connected by a suction passageway 85 with a suction port 86 in the mixture conduit wall posterior to the throttle, so that diaphragm 10 moves responsive to variations in manifold suction.

A second vertical guide 88 of rectangular cross section extends into constant level chamber 83 adjacent guide 18 and slidably receives a gooseneck link 89 having at its upper end an offset portion 90 formed with a horizontal ledge 9|. Ledge 9| has an aperture in its outer end portion which slidably receives diaphragm stem 19. The upper end portion of stem 79 is of slightly less diameter than the remainder of the stem to form a shoulder 92, the function of which is described below. An angular bracket 93 has an aperture 94 at one end for slidably receiving this narrow portion of stem 79, and has a pin 95 at its other end for attachment of metering pin 65. The bracket normally seats on the upper portion 9| of link 89 or stem shoulder 92, whichever is uppermost and itself seats a coiled compression spring 96, retained on stem 19 by a keyed or otherwise retained washer 91. Link 89 at its lower end is connected by a small link 98 to a arm 99 rigid with throttle shaft 8|, so that upon opening movement of the throttle, link 89 moves upwardly, carrying with it bracket 93 and resiliently, by means of spring 98, urging stem 19 and diaphragm l0 upwardly, as in Fig. 6. When the decrease in suction occurs at a greater rate than opening of the throttle valve, shoulder 92 of stem 19 engages bracket 93 to further elevate metering pin 65 as in Fig. 5. When suction remains high, even though the throttle is being opened, diaphragm l0 prevents upward movement of stem 19; upward movement of link 89 by the throttle elevates bracket 93 and the metering pin while compressing spring 98, as in Fig. 6. During closing movement of the throttle, spring 98 again urges bracket 93 downwardly against either shoulder 92 or ledge 9|, whichever is uppermost, so that lowering of the metering pin is limited by one of these elements.

Operation of the device is as follows: Fuel is drawn into the pumping chamber by downward movement of the diaphragm resulting from increase in manifold suction. Thereafter, the .diaphragm may move upwardly either upon a drop in suction or upon opening movement of the throttle through linkage 89, upward movement of ledge 9| being transmitted to stem 19 via bracket 93, spring 88, and washer 91. The position of b k 93, a d c ns u f mete in p n 65, is governed by whichever of the elements, ledge 9! or shoulder ,92, is uppermost, downward or closing movement of the metering pin being thereby limited by the amount of suction or the degree of opening of the throttle.

It should also be noted in this connection that by shortening the length of travel of link '98 this device may be constructed so that the throttle connection cannot fully elevate the metering pin, the last portion of metering pin elevation and final movement .of the diaphragm in the pumping direction being produced by a further decrease in suction.

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 comes within the scope of the appended claims is contemplated.

I claim:

1. In a carburetor, a downdraft mixture conduit having a throttle therein, a constant level fuel bowl adjacent the same, a recess in the bottom wall of said bowl, a horizontal diaphragm extending across said recess and dividing the same into an accelerating pump chamber above said diaphragm and a suction chamber below said diaphragm, said diaphragm being sealingly secured over said recess, inlet and outlet passages connecting said pump chamber, respectively, to said bowl and said conduit, a suction passage connecting said suction chamber to said mixture chamber below said outlet passage, a spring urging said diaphragm upwardly in opposition to suction thereon, a tubular guide extending vertically from such recess into said fuel bowl above the normal fuel level therein, an operating stem centrally secured to said diaphragm and extending upward through said guide and terminating within said bowl, a second tubular guide extending vertically into said bowl, a second stem having an offset portion slidably carried by said operating stem, a link connecting said second stem to said throttle, and spaced abutments on said diaphragm operating stem forming a lost motion operative connection between said second stem and. said throttle and said first stem and said diaphragm.

2. In a carburetor, a downdraft mixture conduit having a throttle therein, a constant level fuel bowl, an enclosed depression in the bottom of said bowl, a diaphragm dividing said depression into a pump chamber and a suction chamber, inlet and outlet passages, respectively, connecting said pump chamber to said bowl and said conduit, a suction passageway connecting said suction chamber to said conduit posterior to said throttle, an operating stem attached to said diaphragm and having a resilient, one-way operating connection with said throttle, a metering orifice element within said bowl, a metering pin slidably and resiliently secured to said stem for elevation therewith upon reductions in suction and for elevation with said one-way connection upon opening movements of said throttle.

3. In a carburetor, a downdraft mixture conduit having a throttle therein, a constant level fuel bowl adjacent the same, a depression in the bottom wall of said bowl, a diaphragm sealingly said suction chamber to said mixture chamber.

below sa d out t pas age, a .fue p ssage connecti s sai bowl w th sai condu t, a me e ing orifice e em nt f r o trollin the flow of fuel through a pas e, a m tering p n in aid orifi e, a tubular guide extending vertical-y from said. ,Gup, an operating stem centrally secured .to said diaphragm and extending upward through said guide and terminatingwithin said bowl, a spring on said guide for urging said stem upwardly in opposition to suction ,on said diaphragm, an u wardly facing shoulder on said stem, a second guide extending vertically into said bowl, av link slidable in said second guide, said link at its lower extremity being operatively connected to the throttle and having at its upper extremity a horizontal ledge slidable on said operating stem, a bracket slidably carried by said stem above said. shoulder and also above said ledge, and a second spring on said stem for urging said bracket down-- ward, said metering pin being attached to said. bracket for movement therewith.

4. In a carburetor, a mixture conduit having a throttle therein, a fuel bowl, an accelerating pump pressure chamber formed in a wall of said bowl, a diaphragm sealingly closing said chamber, inlet and outlet fuel passages, respectively, connecting said chamber to said bowl and said conduit, a suction chamber formed on the outer side of said diaphragm and a suction passage con necting the same to said conduit, a pair of tubular guides extending upwardly into said bowl, an operating stem extending from said diaphragm through one of said guides, a link connected to said throttle and extending through the other guide and having a lost-motion, operative connection to said stem, and a spring constantly urging said diaphragm in opposition to the suction effect thereon for causing pump discharge upon a drop in suction, said stem being located wholly within the confines of said bowl and said link being wholly within said bowl except for the extremity thereof connected to said throttle.

5. A carburetor as specified in claim 4 further including a metering orifice element within said bowl and a metering pin carried by said stem above the guide receiving the same and wholly within the confines of said bowl.

6. In a carburetor, a downdraft mixture conduit having a throttle therein, a constant level fuel bowl adjacent the same, a recess in the bottom wall of said bowl, a flexible diaphragm sealingly secured over and forming the outer wall of said recess, inlet and outlet passages, respectively, connecting said recess to said bowl and said conduit, a tubular guide extending vertically into said bowl to a point above the normal fuel level therein, an operating stem centrally secured to said diaphragm and extending upwardly through said guide and terminating within said bowl, a second tubular guide extending vertically into said bowl, and a link connected at its lower extremity to said throttle and slidably received in said second guide, said link having an oif-set portion and said stem having an abutment near its upper extremity forming a one-way connection between the two whereby opening movement of said throttle moves said diaphragm upwardly to inject an accelerating charge into said conduit.

7. In a carburetor, a mixture conduit having a throttle therein, a constant level fuel bowl, a wall of said bowl having restricted, oppositely cupped parts forming a chamber, a diaphragm mounted between said cupped wall parts and forming a pump chamber and a suction chamber, restricted inlet and outlet passages, respectively, connecting said pumping chamber to said bowl and said conduit, a suction passage connecting said suction chamber to said conduit posterior to said throttle, an actuating stem projecting from said diaphragm into said bowl, a guiding and sealing sleeve projecting from the inner of said cupped wall parts inwardly along said stem, an operating connection between said throttle and said stem inwardly of said sleeve, a metering orifice element within said bowl, a metering pin cooperating with said orifice element, and

JOHN S. CAR/REY.

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

UNITED STATES PATENTS Number Name Date 2,109,260 Chandler et a1 Feb. 22, 1938 2,145,672 Udale Jan. 31, 1939 2,186,480 Ensign Jan. 9, 1940 2,207,456 Cofiey July 9, 1940 2,271,116 Bracke et al. Jan. 27, 1942 2,299,872 Ball Oct. 27, 1942 2,312,817 Heftler Mar. 2, 1943 2,328,604 Bicknell Sept. 7, 1943 2,340,820 Moseley Feb. 1, 1944

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