US2736540A

US2736540A - Carburetor

Info

Publication number: US2736540A
Application number: US251508A
Authority: US
Inventors: Robert R Dorland
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1951-10-16
Filing date: 1951-10-16
Publication date: 1956-02-28
Anticipated expiration: 1973-02-28

Description

Feb. 28, 1956 a. DORLAND 2,736,540

CARBURETOR Filed Oct. 16, 1951 2 Sheets-Sheet 1 70 .32 4 50 4 /0 76 3 62 i4 6 1 M 56 60 56 [I /6 .52 54 .30 l

INVENTOR: EO QEETB DQCLAND ATwE/VEY Feb. 28, 1956 R, R DQRLAND 2,736,540

CARBURETOR I 2 Sheets-Sheet 2 Filed Oct. 16. 1951 IN VEN TOR.

gee/5:1 BDozuw W 4 7% ATTDEAEY United States Patent Office 2,736,540 Patented Feb. 28, 1956 CARBURE'IDR Robert R. Dorland, Detrolt, Mich aaslgnor to Bendix Aviation Corporation, South Bend, Ind, I corporation of Delaware Application October 16, 1951, Serial No. 251,508 4 Claims. cl. 261-43) The present invention relates to carburetors, and more particularly to a vacuum actuated power enrichment means and accelerating pump for carburetors.

One of the principal objects of the present invention is to provide an accurately controlled vacuum actuated power enrichment means for a carburetor.

Another object of the invention is to provide in a carburetor a valve means for coordinating the operation of a vacuum actuated power enrichment means with the movement of the carburetor throttle valve.

A further object. of the invention is to provide in a carburetor a valve construction for controlling the vacuum passage of a vacuum actuated accelerating pump and/or power enrichment means, which construction will facilitate close control of said pump and enrichment means, and will permit wide tolerance limits of the parts of the pump and enrichment means.

Additional objects and advantages will become apparent from the following description and accompanying drawings, wherein:

Figure 1 is a vertical cross-sectional View of a carburetor in which some of the parts have been rearranged to more clearly show their construction and operation;

Figure 2 is a cross-sectional view of the carburetor taken on line 2-2 of Figure 1, showing the throttle valve assembly; and

Figure 3 is a fragmentary cross-sectional view of a carburetor showing another arrangement of my invention.

Referring more specifically to the drawings, Figure 1 shows a carbuetor which, for the present description, may be considered as being a conventional float type downdraft carburetor having an induction passage 10, an air inlet 12, a mixture outlet 14, primary and

secondary venturis

16 and 18, respectively, and a throttle 20 mounted on a throttle shaft 22 in the carburetor induction passage. A float chamber 24 is mounted along one side of the induction passage and is connected with the throat of the secondary venturi by a main discharge jet 26 inclined upwardly from a point near the bottom of the float chamber. The main jet contains a fuel metering jet 28 and a perforated tube 30 through which air from vent 32 passes into the interior of the tube, where it mixes with the fuel to form a fuel-air emulsion to be discharged through an annular space 34 at the throat of the secondary venturi. The float chamber 24 is vented to the induction passage through duct 36 and contains a float 38 for controlling a. conventional fuel inlet valve (not shown). A choke valve 40 is shown mounted on a shaft 42 in the air inlet.

A power enrichment passage 50 connects the float chamber with the main discharge jet posterior to the fuel metering jet and is controlled by a restriction 52 and a valve 54 urged to its closed position by a coil spring 56 disposed around valve stem 58 and reacting between a shoulder 60 and a washer 62 secured to said stem. Disposed directly above valve 54 and secured to the float chamber cover is a cylinder 70 connected at its upper end through a conduit 72 with the induction passage on the engine side of the throttle, and also with the air inlet 12 posterior to the choke valve by a bleed 74. A piston 76 is disposed cylinder and carries a downwardly extending stem 78 around which is disposed a coil spring 80 reacting between a washer 82 secured at the lower end of the cylinder and a flange 84 on the lower end of said stem.

Conduit 72 passes through the throttle bearing, which in cooperation with the throttle shaft forms a valve as shown at numeral 90. The throttle shaft at this point contains a slot 92 which connects the horizontal and

vertical sections

94 and 96, respectively, of conduit 72. As the throttle shaft rotates during the opening movement, the solid portion 98 of the shaft adjacent the slot interrupts, at a predetermined point, communication between the said vertical and horizontal sections of the conduit. For simplicity in construction and operation, the throttle shaft and bearing form the valve for controlling conduit 72; however, it is apparent that a structurally independent valve actuated by the throttle mechanism could be substituted for the structure shown.

In the operation of the carburetor when the engine is running and the throttle is closed to a point where valve is open, manifold vacuum is transmitted to cylinder 70 above piston 76 and lifts said piston and stem 78 in opposition to spring 80 so that the lower end of the stem does not contact stem 58. The piston and stem 78 are held in this position by manifold vacuum until the throttle is opened to the point where portion 98 of the shaft closes conduit 72 and permits bleed 74 to return the pressure in cylinder 70 to substantially atmospheric pressure. Under this condition, spring 80 lowers stem 78 contacting stem 58 and opening valve 54 to admit additional fuel into the main discharge jet for high power output. As the throttle is moved toward closed position, portion 98 of the throttle shaft opens conduit 72, permitting vacuum to be transmitted to cylinder 70 and to raise piston 76 and stem 78. Spring 56 then closes valve 54, leaving the main metering jet 28 as the sole source of supply for the main discharge jet, thus providing an economical fuel mixture for moderate engine'operation.

In the modified form of my invention shown in Figure 3, a vacuum actuated power enrichment valve and accelerating pump are combined. In this arrangement a power enrichment valve 100 urged to closed position by a spring 101 is actuated by an accelerating pump bellows 102 which is urged downwardly by a spring 104. The internal portion of the bellows is connected by conduit 72 and bleed 74 to the induction passage on the engine side of the throttle valve in the same manner as in the embodiment of Figures 1 and 2. The pump and power enrichment jet construction of this embodiment is more fully described and claimed in patent application Serial Nos. 93,999, filed May 18, 1949, 130,523, filed December 1, 1949, and 200,086, filed December 9, 1950. In this construction, a compound spring arrangement may be used to permit the accelerating pump to operate to a limited extent before the throttle is opened to the point where conduit 72 is closed by the throttle .shaft cutting off the vacuum to bellows 102 and permitting it to become extended sufficiently to open valve 100. Fuel for both power enrichment and acceleration flows from the float chamber through valve and conduit 112.

For certain engine installations it may be desirable to control the operation of the accelerating pump by my valve construction independently of the power enrichment valve. Other modifications may be made to suit requirements.

I claim:

1. In a carburetor: an induction passage, a throttle in said passage, a shaft and bearing for said throttle, a float chamber, a main discharge jet connecting said. chamber with the induction passage, a passageway connecting said chamber with said jet, a valve in said passageway, a cylinder, a piston in said cylinder, a stem connected to said piston and adapted to contact and open said valve, a spring urging said stem and piston in the direction to open said valve, a conduit connecting said cylinder with said throttle shaft bearing, a constantly open bleed passageway connecting said conduit with the induction passage on the air intake side of the throttle a second conduit connecting said bearing with the induction passage on the engine side of said throttle, and a channel in said shaft at the point where said conduits intersect said hearing adapted to connect said conduits only when said throtlit) is closed a predetermined degree.

2. In a carburetor: an induction passage, a throttle in said passage, a shaft and bearing for said throttle, a fuel bowl, a main discharge jet connecting said bowl with the induction passage, a passageway connecting said bowl with said jet, a valve in said passageway, a chamber, a movable member forming a wall of said chamber, a spring for urging said member in the direction to open said valve, a conduit connecting said chamber with said throttle shaft bearing, a constantly open bleed passageway connecting said conduit with the induction passage on the air intake side of the throttle, a second conduit connecting said hearing with the induction passage on the engine side of said throttle, and a channel in saidshaft at the point where said conduits intersect said bearing adapted to connect said conduits only when said throttie is closed a predetermined degree.

3. in a carburetor: an induction passage, a throttle in said passage, a shaft and bearing for said throttle, a float chamber, a main discharge jet connecting said chamber with the induction passage, a passageway connecting said chamber with said jet, a valve in said passageway, a vacuum responsive means, a spring urging said means in the greases .direction to. open said valve, .a conduitconnecting said means with said throttleshaft bearing, a second conduit connecting said bearing with the induction passage on the engine side of said throttle, a channel in said shaft at the point where said conduits intersect said bearing adapted toconnect said conduits only when said throttle is closed a predetermined degree, and a constantly open 7 bleed passageway connecting said first mentioned conduit with the induction passage upstream of the throttle.

4. in a carburetor: an induction passage, a throttle in said passage, a shaft and bearing for said throttle, a float chamber, a main discharge jet connecting said chamber with the induction passage, a metering restriction in said jet, a passageway connecting said chamber with said jet on the downstream side of said restriction, a valve in said passageway, a vacuum responsive means, a spring urging said means in the direction to open said valve, a conduit connecting said means with said throttle shaft bearing, a second conduit connecting said bearing with the induction passage on the engine side of the throttle, a channel in said shaft at the point where said conduits intersect said bearing adapted to connect said conduits only when said throttle is closed a predetermineddegree, and a bleed passageway connecting said vacuum responsive means and the induction passage on the air intake side of said throttle.

References titted in the file of this patent UNITED STATES PATENTS 1,909,389 Ball et al May 16, 1933 2,038,206 Chandler Apr. 21, 1936 2,212,946 Mock et al. Aug. 27, 1940 2,313,258 Olson Mar. 9, 1943 2,363,223 Bonnier Nov. 21, 1944 2,557,111 lorgensen et al. June 19, 1951