Carburetor

July 9, 1935.

2,007,337

M. MALLORY

CARBURETOR

Filed Dec. 12, 1933

Sheets-Sheet 1

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July 9, 1935.

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M. MALLORY

CARBURETOR

Filed Dec. 12, 1933

2,007,337

Sheets-Sheet 2

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July 9, 1935. m. mallory 2,007,337

CARBURETOR

Filed Dec. 12, 1933 3 Sheets-Sheet 3

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Qttowcy

Patented July 9, 1935

2,007,337

UNITED STATES PATENT OFFICE

2,007,337

CARBURETOR

Marion Mallory, Detroit, Mich., assignor to The Mallory Research Company, Toledo, Ohio, a corporation of Delaware

Application December 12, 1933, Serial No. 702,051

Claims. (CL 261—61)

This invention relates to an improvement in When the engine is operating, the liquid fuel carburetors, having for its object primarily to pro- passes from the chamber If through a port 23, vide a variable venturi controlled by the vacuum between the engine and the throttle and the 5 velocity of air passing through the carburetor.

In the present embodiment of the invention, the venturi has fuel inlet ports directed toward the center of the venturi, within which is a valve. Control of this valve depends upon two factors, 10 namely, the degree of vacuum in the intake passageway and the velocity of the air passing therethrough. Provision is also made for shutting off the vacuum control, whenever the engine isidling or operating at a comparatively low speed with 15 high vacuum.

The relation of the valve to the fuel intake, the manner in which the valve is controlled and the advantages resulting therefrom will be more fully explained in connection with the accompany!0 ing drawings, in which,—

Figure 1 is a longitudinal sectional view of a carburetor constructed according to the invention.

Figure 2 is a plan view of the carburetor.

!5 Figure 3 is an elevation looking from the left of Figure 1.

Figure 4 is an elevation looking from the right of Figure 1.

Figure 5 is a sectional detail of the venturi 10 taken on the line 5—5 of Figure 1.

Figure 6 is a detail sectional view taken on the line 6—6 of Figure 1.

Figure 7 is a central vertical section showing a modified form of the auxiliary air valve.

Figure 8 is a section through the air valve shown in Figure 7.

Figure 9 is a plan view of the valve seat shown in Figure 7.

Figure 10 is a diagrammatic illustration of the ® low speed fuel supply and its adjustment.

As illustrated in the drawings, the invention . is associated with a carburetor which comprises a lower casting 10 formed with a fuel chamber 11 and an air chamber 12, and an upper casting 13 &lt;5 formed with a passageway 14 leading to the intake manifold. Admission Of air to the chamber 12 is controlled by a choke valve 15 and a throttle valve 16 is mounted within the passageway 14.

The two castings 10 and 13 are secured together ¹⁰ by screws 17 or similar means and are formed with opposed annular shoulders 18 and 19 between which is secured a member 21 forming a venturi 22, through which air is drawn from the chamber 12 past the fuel ports 28 into the passageway ® 14.

which is regulated by a needle valve 24, into a passageway 25 which is provided with an air bleed 25^tt, and thence through a port 26 into an fi annular channel 27 in the member 21, from which it is discharged through a plurality of ports 28, immediately above the narrow portion of the venturi 22.

In accordance with the present embodiment of 10 the invention, the casting 13 is formed with a web 29 extending diametrically across the passageway 14 below the throttle valve and in the same plane as the throttle valve axis. Extending downwardly from the web 29 is a hollow stem 30 constituting 15 a bearing member on which the auxiliary air valve 31 is reciprocably mounted. A spring 32 within the stem 30 urges the valve 31 toward its closed position, shown in dotted lines in Figure 1, but under certain predetermined operating condi- 20 tions, the valve is adapted to be opened by suction from the intake manifold through the passageway 33, in opposition to the spring 32. The closing movement of the valve is positively limited by the engagement of its nose 34 with a 25 vertically adjustable stud 35 which is secured in the bottom of the casting 10. When the valve drops to a nearly closed position, the velocity of the air passing through the venturi is increased, drawing more fuel through the ports 28 30 and enriching the mixture.

It is desirable to cut off the valve 31 from the influence of suction from the manifold when the throttle is closed or nearly closed. In the present construction, communication between the 35 passageway 33 and the intake chamber 14 is through a groove 37 around the valve stem 38 and through a port 39. The inlet from the passageway 33 to the groove 37 is closed when the throttle is not open more than one eighth of its ⁴⁰capacity.

When the engine is idling, with the throttle closed, fuel is supplied to the intake in any suitable manner. As shown in Figures 1 and 3, there ₄₅is a by-pass 42, 43 for this purpose, leading from a branch 25^b of the fuel channel 25 into the center of the intake 14 at a point 40 at the. center of the throttle valve stem, which is formed with a little venturi 41. The low speed adjust- 50 ment screw is shown at 45.

In the modification shown in Figure 7, the auxiliary air valve 46 has an annular lower end adapted to engage a seat 48, which is in the form of a spider, to limit the closing movement ®^s

2,007,337 tle is not open beyond a predetermined position.

2. The combination with an intake passageway having a fuel inlet, an air inlet, and a throttle valve for said passageway, of a valve for said 6 air inlet, a passageway from the intake through the throttle valve stem to the air inlet valve and tending to open the latter by suction from the intake, said throttle valve stem being adapted to cut off the suction from said air inlet valve 10 whenever the throttle is not open beyond, a predetermined position.

3. The combination with ah intake passageway having a fuel inlet, an air inlet formed with a venturi, and a throttle valve for said passage- 15 way, of a valve for said air inlet within the venturi, a passageway from the intake through the throttle valve stem to the air inlet valve and tending to open the latter by suction from the intake, said throttle valve stem being adapted 20 to cut off the suction from said air inlet valve whenever the throttle is not open, beyond a predetermined position.

4. The combination with an intake passageway having an inlet formed with a venturi, a fuel 25 inlet into the venturi, and a throttle valve for said passageway, of an air inlet valve within the venturi, a passageway from the intake to the air inlet valve and tending to open the latter by suction from the intake, and means connected 30 with the throttle valve for cutting off the suction from said air inlet valve whenever the throttle is not open beyond a predetermined position.

5. The combination with an intake passageway having an inlet formed with a venturi, a fuel 35 inlet into the venturi, and a throttle valve for said passageway, of an air inlet valve within the venturi, a passageway from the intake through the throttle valve stem to the air inlet valve and tending to open the letter by suction from the ⁴⁰intake, said throttle valve stem being adapted to cut off the suction from said air. inlet valve whenever the throttle is not open beyond a predetermined position.

6. In combination, an intake passageway hav- 45 ing an inlet, a throttle valve within said passageway, an air valve supported between said inlet and the throttle valve, communicating means from said air valve through the axis of the throttle valve to a point in the intake passageway 50 beyond the throttle valve and operable by a predetermined degree of vacuum in the intake passageway to open said air valve, and means connected with the throttle valve for cutting off the suction from said air valve whenever the throttle 55 valve is not open beyond a predetermined position.

7. In combination, an intake passageway having an inlet formed with a venturi, fuel inlets into the venturi, a throttle valve on the engine 66 side of the venturi, an air valve within the venturi, a spring tending to close the air valve, an abutment preventing complete closure thereof, a passageway through which a predetermined degree of vacuum on the engine side of the ⁶⁵throttle valve is operable to open the air valve away from said abutment without varying the size of the fuel inlets, and means connected with the throttle valve for cutting off the suction from said air valve whenever the throttle valve is not open beyond a predetermined position.

8. Tn combination, a fuel mixing chamber having an air inlet and fuel inlets, a throttle valve on the engine side of said chamber, an air valve within said chamber on the engine side of said ⁷ⁱ of the valve. The seat 48 Is supported by a tubular stud 49, to the lower end of which is connected a tube 50 leading from the passageway 25. The valve 46 is also provided with up5 wardly and outwardly inclined passageways 51, through which the fuel is drawn when the throttle is open.

Tn the operation of the invention, when the engine is running under a normal load with the 10 throttle, say, half way open, the auxiliary air valve 31 or 46 will be held open by the vacuum developed in the intake. But if the throttle is suddenly opened wider, relieving the vacuum, the auxiliary air valve will tend to close, 16 thereby enriching the mixture, until the engine picks up speed.

With the throttle wide open, even with the engine running at high speed, if the operation of the auxiliary air valve were dependent en20 tirely on vacuum, there would be a tendency ' for it to close and make too rich a mixture.

With the present construction, however, the velocity of the air passing through the venturi 22 will hold the valve open, thereby supplying 25 a comparatively lean mixture, but whenever the engine slows down under a heavy load, the valve will tend to drop automatically, decreasing the space between the same and the venturi and enriching the mixture, as is desirable under such 30 conditions.

I have also found, however, that if the auxiliary air valve is subjected to the action of suction from the intake, with the engine idling or running at low speed with the throttle nearly 36 closed, there is sufficient vacuum to raise the valve and, when the engine is suddenly accelerated, the valve will not drop quickly enough to prevent a hesitation or flat spot in the operation of the engine. The reason for this is that the 40 mixture under such conditions is too lean for acceleration until the valve drops to its lower position. It is therefore preferable that the valve should be in its lower position when the engine is running at low speed or idling and, to make this 45 possible, I have arranged the groove 37 so that it will be closed, thus shutting off the vacuum from the auxiliary air valve whenever the throttle is closed, or open less than one eighth of its capacity. Then, when the engine is acceler50 ated, the valve is initially in its lower position and will rise as the speed of the engine or the degree of vacuum increases.

From the above description, it will be seen that the auxiliary air valve is controlled auto55 matically, partly by suction from the intake and partly by the velocity of the air passing through the venturi 22, but that the suction is cut off whenever the throttle is closed, or open less than one eighth of its capacity.

The invention may be applied to any type of carburetor and while I have shown and described in detail the preferred embodiment thereof, it is apparent that the same may be considerably modified without departing materially from the 65 scope of the appended claims.