US2726648A - Carburetor - Google Patents

Description

T. J. REDD CARBURETOR Dec. 13, 1955 2 Sheets-Sheet 1 Filed Jan. 5, 1955 Pmzss zmz DIFFERENTIAL 30 m kIEm Dec. 13, 1955 Filed Jan. 5, 1953 T. J. REDD CARBURETOR 2 Sheets-Sheet 2 United States Patent CARBURETOR Thomas I. Redd, Tulsa, Okla.

Application January 5, 1953, Serial No. 329,671

3 Claims. (Cl. 123-119) My invention relates to improvements in carburetors for internal combustion engines and the objects of my invention are, first, to provide an air measuring section which more accurately senses the weight flow of air flowing into a carburetor than does the well known venturi, second, to furnish a positively driven pressure actuated fuel pump that is responsive directly to the air measuring section and third, to provide an automatic priming fuel nozzle for injecting fuel directly into the engine intake manifold.

I attain these objects by the mechanism illustrated in the following drawings.

Figure l is a cross section of the carburetor showing the air measuring section, a diaphragm pumping unit for use on normally aspirated engines and the fuel injector.

Figure 2 is a graph which shows the air flow characteristics of a venturi section, of a fine tube section in viscous flow and an ideal section.

Figure 3 is a drawing of a diaphragm pumping unit with a balanced diaphragm for use on an engine which is to be supercharged. v U

Figure 4 shows a balanced piston type motor with a plunger pump element also suitable in supercharger applications.

The pumping units of Figure 3 and Figure 4 may take the place of the pumping unit of Figure 1.

In the drawings in Figure 1, item 1 is the carburetor air intake, 2 is the air measuring section consisting of a plurality of drilled passages, 3 is the throttle section, 4 is the engine intake manifold, 5 is a tube connecting the air intake to the diaphragm chamber 6, item 7 is a tube connecting the air measuring section to the diaphragm chamberS, diaphragm 9 separates the chambers 6 and 8 and connects through circumferential line 10 to the annular fuel pump diaphragm 11, diaphragm 11 is attached at its inner and outer extremities to pump body 12 which contains intake chamber 13 into which leads line 14 from a fuel supply not shown, port 15 on which seats valve 16 leads from the intake chamber 13 to the annular chamber 17, port 18 on which seats valve 19 leads from the annular chamber 17 to discharge chamber 20 to which is connected discharge line 21. Line 21 carries fuel to the injector body 22 containing the jet 23 and the ports 24, valve disc 25 forms a valve at contact with jet 23 isolating the jet from the ports 24 and through opening 26 in the center of the valve disc passes the fuel from jet 23 into passage 27 which leads to the intake manifold 4. Item 28 is an oscillating push rod for moving the diaphragm assembly of items 9 and 11. The engine camshaft may be used to actuate the push rod 28.

In Figure 3, and referring to Figure 1, item 29 is a tube connecting the air intake 1 to the diaphragm chamber 30, item 31 is a tube connecting the air measuring section 2 to the diaphragm chamber 32, diaphragm 33 separates the chambers and 32 and is attached to the fuel pump drive rod 34, drive rod 34 is led from chambers 30 and 32 by the bushings 35 and 36 respectively, vented disc 37 lCC connects the rod 34 to the annular fuel pump diaphragm 38 which is attached at its inner and outer extremities to pump body 39 which contains intake chamber 40 into which leads line 41 from a fuel supply not shown, port 42 on which seats valve 43 leads from the intake chamber to annular chamber 44, port 45 on which seats valve 46 leads from annular chamber 44 to the discharge chamber 47 to which connects discharge line 48 leading to the injector body 22 of Figure 1. Item 49 is an oscillating push rod, preferably driven by the engine, for actuating the drive rod 34.

In Figure 4, and referring to Figure 1, item 50 is a tube connecting the air intake 1 to the cylindrical chamber 51, item 52 is a tube connecting the air measuring section 2 to the cylindrical chamber 53, item 54 is a slidable piston section separating chambers 51 and 53 and is attached to the pump drive rod 55, rod 55 is led from chambers 51 and 53 by bushings 56 and 57 respectively, drive rod 55 connects to plunger 58 which slides in a cylinder formed in pump body 59, item 60 is the fuel pump inlet chamber which receives fuel from a supply not shown through line 61 and port 62 whereupon seats valve 63, port 64 on which seats valve 65 passes fuel from the pump cylinder to discharge chamber 66 leading to discharge line 67 which connects to the injector body of Figure 1. Item 68 is an oscillating push rod, which may be driven by the engine, for moving the drive rod 55.

The operation of the carburetor is'according to the following: a

When the engine is being started the intake manifold pressure is just a few inches of mercury below atmospheric pressure and the valve disc touches the fuel jet 23. The suction causes flow through the jet, through the opening in the disc and into the manifold.

When the engine is running the manifold depression will be about sixteen inches of mercury which will flex the valve disc away from the jet. The proportions of the ports 24 and the valve disc opening 26. allow for a suction in the chamber above the disc to draw in the proper amount of fuel for idling and light load operations when air flow through the air measuring section is slight. At wide open throttle the valve disc will again approach the jet by reason of the low manifold depression and the required mixture enrichment will be produced.

When the throttle section, shown in Figure l, is opened, air is drawn through the measuring section 2, a lowering of pressure in the air stream takes place and this pressure depression indicates the amount of air flowing therein. In an ordinary carburetor the fuel jet is placed in the low pressure region whereupon atmospheric pressure above the fuel in the float chamber forces fuel through the jet to pressure diflerentials often just a few inches of water. However these differentials may be greatly amplified by use of the diaphragm apparatus of the present invention. In Fig. 1 the push rod lifts the diaphragm assembly and fuel is drawn into the pump. A pressure differential is applied to diaphragm 9 and the pump pressure becomes equal to the pressure differential multiplied by the area ratio of diaphragm 9 to diaphragm 11 being less, equal or greater in pressure according to the ratio. The net effective area of diaphragm 9 lies outside the circumference 10 since the pressures on the diaphragm faces inside the circumference are equal and atmospheric if the engine is not supercharged.

In Fig. 3 and Fig. 4 are represented balanced diaphragm and balanced piston designs, respectively. The fuel pump pressure will be proportional to the pressure differential regardless of supercharging in these designs which may take the place of the diaphragm device of Fig. 1 if desired.

These devices may use any pressure differential to control an engine.

In Fig. 2 the relation of weight flow of air to the flow section pressure differential is described for three flow sections. Weight flow varies as the first power of the pressure differential in a fine tube section as the flow is viscous, or laminar, in character. In the ideal section weight flow of air should be proportional to the square root of the air pressure differential since the weight flow of fuel also follows this law and the object is to have a constant air-fuel ratio. In the venturi section the volume flow follows the square root law but the weight flow falls below the ideal because of lower air density at the higher differentials. A venturi section will give favorable results with the diaphragm actuated pumps of Figures 1, 3 and 4 at low air pressure differentials.

.A measuring section made up of straight walled tubes can be designed which will closely approach the ideal section in operation. By using the proper tube length and diameter in relation to pressure differential and fiow expected the section can be made to operate in a specific region of the turbulent flow curve wherein the flow characteristic will be superior to the venturi section characteristic.

In accordance with the provision of the patent statute I have described the principle of my invention together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the aparatus is only illustrative and that the invention maybe carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States of America is:

1. In a carburetor, an air measuring section, said air measuring section having a cylindrical hollow air measuring passage, and the air fiow character in said passage being maintained between definite limits in the turbulent flow region whereby the weight flow of air through said passage is nearly proportional to the square root of the pressure differential between the air entering said passage and the air leaving said passage.

2. In a carburetor, a fuel injector, said fuel injector having its interior part in communication with the inside of-the engine intake manifold, and a resiliently held valve disc, said valve disc engaging the interior part of the fuel injector near the periphery of the valve disc, and said valve disc receiving the pressure of the engine intake manifold on one face, and said valve disc having an opening in its central part, and a fuel jet, said fuel jet forming a valve with the face of said valve disc opposite to that face which receives the engine intake manifold pressure, and fuel from the fuel jet being led into the engine intake manifold through said opening in the valve disc, and port means in the injector communicating the atmosphere to the face of the valve disc that engages the fuel jet, and fuel feeding means leading to the fuel jet from the carburetor. I

3. In a carburetor, a piston motor, said piston motor having a piston slidabl-y disposed in an enclosure, and a fuel pump, said fuel pump mechanically actuated by the piston motor, and said fuel pump having inlet and outlet passages, and fuel feeding means leading to the fuel pump inlet passage, and conduit means leading from the fuel pump outlet passage ,to :an engine, and an oscillating force means, said fuel pump driven in .one direction by said oscillating force means wherein the fuel pump makes its intake stroke and said ,fuel pump being driven in the opposite direction on its discharge stroke by said piston motor when the pressure at one point in the stream of the working medium of an engine is led to one face of said piston and a lower pressure at another point in the stream of the working medium of an engine is led to the opposite face of said piston while said oscillating force means is withdrawn.

References Citedin the file of this patent UNITED STATES PATENTS 1,248,058 Bailey Nov. 27, 1917 1,567,051 Gronkwist Dec. 29, 1925 1,890,497 Dalgliesh Dec. 13, 1932 2,052,560 French Sept. '1, 1936 2,183,035 Weber'et al Dec. '12, 1939 2,212,946 Mock et al. Aug. 27, 1940 2,253,454 Voit Aug. 19, 1941 2,484,418 Mercier Oct. 11, 1949 2,562,656 Blakeslee July 31, 1951

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