US2552056A - Carburetor priming means - Google Patents

Description

y 1951 A. w. ORR, JR 2,552,056

CARBURETOR PRIMING MEANS Filed Dec. 21, 1946 3 Sheets-Sheet l Orr Ji:

1 N VEN TOR.

May 9 1952 A. w. CRR, JR 2,552fi5fi CARBURETOR PRIMING MEANS Filed D60. 21, 1946 s Sheets-Sheet 2 Ana/r 0 J1:

[N V EN TOR.

y 1951 A; w. ORR, JR 2,552,056

CARBURETOR PRIMING MEANS Filed Dec. 21, 1946 3 Sheets-Sheet 3 or) Jr.

IN V EN TOR.

Patented May' 8, 1951 CARBURETGR PRIMING MEANS Andrew William Orr, J r., Detroit, Mich., assignor to George M. Holley and Earl Holley Application December 21, 1946, Serial No. 717,673

The object of this invention is to incorporate in a small automotive or aircraft carburetor, of the pressure type, automatic priming means to take the place of the standard type of choke in general use for many years.

A further object of this invention is to incorporate in a small automotive or aircraft carburetor, of the pressure type, a cheap, simple, easy to manufacture and easily adjustable idle system.

This application is a continuation in part of my copending application filed August 8, 1946, Serial No. 689,260.

Fig. 1 is a cross-sectional elevation showing the essential elements of my invention.

Fig. 2 shows an alternative construction of my invention.

Fig. 3 shows a second alternative construction of my invention.

In Fig. 1 I is the air entrance, I2 is the venturi, H! is a throttle located downstream from the venturi I2, I6 is a mixture outlet into which the fuel nozzle I8 discharges.

293 is a link connecting the throttle I4 with a cam 24, a link 22 is the manual throttle control link. The cam 24 engages with a cap '26,,which engages with a spring 28, which engages with a diaphragm 30. By this means increased pressure is applied to the diaphragm 30 as the throttle I4 approaches its idling position.

32 is a passage through which the pressure in the air entrance In is applied to chamber 35 and thus to the upper surface of the diaphragm 3b, which diaphragm thereby responds to air flow because a restriction 3 5, which is an opening in the throat of the venturi I2, applies Venturi suction to the chamber 33 and thus to the lower side of the diaphragm 30.

A fuel control element 31 is engaged by the element 35 which in its turn is engaged by the air flow responsive diaphragm 3G and the ele ment 3'! is also engaged by a diaphragm 38. This element 3'! engages with the diaphragm 38 and controls the flow of fuel past a conical valve 5b which is an integral part of the element 31.

An idle needle 42, connected through a lever 44 with the throttle I i, provides the low speed fuel control means. When the throttle M is opened any appreciable amount the needle 42 is withdrawn entirely and offers thereafter no resistance whatever to the flow of fuel. The resistance to the flow of fuel is then that due to the restriction 30 without the needle 42. Normally, therefore, the fuel flow through restriction 40 causes a pressure drop across fuel diaphragm 38 which 2 Claims. (Cl. 261-39) balances the impressed air differential across air diaphragm 30 plus the pressures exerted by the two springs 28 and 9G. The conical valve 555 regulates fuel flow so that such balance is maintained. The fuel is admitted to chamber ll from the fuel entrance 46 under approximately constant pressure. The fuel flows to the upper side of diaphragm 38, to the chamber 52 through the restriction 40 and (when the throttle is closed) past the needle 42. The fuel leaves the chamber 52 past the conical valve 54 to the passage I134.

The pressure in the outlet passage Iil I is maintained by a constant pressure discharge valve Valve 55 is attached to. diaphragm 5'! and its opening is opposed by spring 58. Chamber 15s is exposed to atmospheric pressure so that the resulting pressure in chamber I52, to the left of diaphragm 51, and passage I04 is determined by the loading of spring 58. This system holds approximately constant fuel discharge pressure at any air flow or fuel flow. Acceleration is provided by the throttle lever M, piston rod '50, link ll, spring 72 and diaphragm I06. A check valve 84 insures the prompt refilling of the chamber 82,

to the left of diaphragm I I16, whenever the throttle is closed. When the throttle is opened sudcontinues to discharge after the throttle M. has ceased to move. A restriction 83 acting in conjunction with the spring 12 prolongs the discharge of accelerating fuel after the rotation of throttle shaft 220 and plate I l has ceased.

One of the novel features of this invention resides in the means of priming the engine when starting, the description of which is as follows: I I0 is a heat responsive bulb located in the inlet manifold H2. H4 is a pipe connecting tempera ture bulb I Ill with a flexible bellows I I 6. Bellows I I6 engages with a lever Hill which carries an adjustable stop I92. Stop I02 engages with a cap 88 enclosing a spring 9% which spring engages with the diaphragm 39. By this means the temperature of the mixture in the inlet manifold H2 regulates the mixture strength by varying the pressure on the spring 90. The fuel is supplied from a source (not shown) through a pump 92, driven by the electric motor as and a storage battery '96. Fuel enters at SI, flows through the pump 92 and is returned'to the fuel entrance Si by the passages 93 and 91. The pressure regulating valve 95 is spring loaded to maintain an approximate constant pressure in the chamber ll. The fuel is discharged by the pump 92 through passage 46 and flows below the diaphragm 38, through the restriction it, past the idle restriction 42, past the metering element 54, down the passage I04, past the valve 53 to the fuel outlet I8.

When the throttle is wide open a richer fuel/air ratio is desired. To obtain this richer fuel/air ratio a pipe I6 connects the underside of the diaphragm M with the inlet passage on the engine side of the throttle I I. A valve 30, unseated by a spring 80, admits fuel from the inlet 36 past a restriction I8 whenever the pressure below the throttle I I rises, which it always does when the throttle is opened. Hence, the fuel/air ratio is temporarily increased whenever the throttle I4 is opened far enough to give manifold pressure sufiicient to open valve 50.

Fig. 2 shows the preferred type of idle system actually used on my carburetor. All fuel except economizer fuel passes through a slot in the throttle shaft, a description of which follows: 40 is the main fuel metering jet. From 40 fuel passes through line 204, into a contoured slot 208, out in throttle shaft 220. Slot 208 matches with a hole I90, from the passage 204. At small throttle openings, the basic idle mixture ratios are determined by the intersection of the contour of slot 208 with passage I99. From slot 203 the fuel passes through line 203, to chamber 52, which is the metered fuel pressure side of fuel diaphragm 38. Packing rings 20!; and 201 are used to prevent fuel leaking along the throttle shaft. In case of slight fuel leakage past 201, drain passage 205 is provided. This passage is mostly vented to the pressure existing above rather than below the throttle I to maintain substantially atmospheric pressure on the left end of the throttle shaft 228. The Welsh plug 222 closes the throttle shaft bore in the throttle body casting to prevent leak. Idle fuel mixture adjustment is secured by a bypass fuel line 202 around the contoured slot 208 in the throttle shaft 220. 200 which increases or decreases the amount of fuel bypassed around slot 208 giving idle fuel/ air ratios. Packing ring 20| is provided to eliminate leakage across idle adjustment 200. The calibration of the idle system consists in contouring the closed throttle portion of slot 208 with hole I90.

The rotation of throttle shaft 220, to close the throttle I4 to the idle range, increases the load on spring 28 because the cap 26 is engaged by the lever through the link 2228, which link 2213 is rotated clockwise by the link 230 connected to the throttle shaft 220 by the lever 232. The cam 226, on the end of the throttle shaft 220, engages with the piston 70 operating the acceleration diaphragm I03, as before, through the spring I2. The valve 60 operates, as before, through the diaphragm l4 and passage 16. The valve 56 is operated, as before, and is controlled by the spring 58, as before. Fuel is discharged, as before, through a nozzle I8.

Temperature in the bulb II is transmitted to a bellows II6, and a stop I02 engages with a cap 88. The cap 88 engages with a spring enclosed therein. As before, an element 31 controls the flow past a needle 52. The element 31 engages an element 36 which engages the air responsive diaphragm 30. When the throttle It opens beyond the idle range the path from the passage I39 to the passage 203 is free and the metering orifice 40 thereafter regulates the mixture fuel/ air ratio.

The other parts are numbered as in Fig. 1 and have the same function.

Fig. 3 shows a second alternative in which when the throttle I4 is moved to its idling DQ51- In bypass line 202 is idle adjustment tion and the needle 42 assumes the position, as shown, the flow through the restriction 40 is limited by the needle 42.

The pressure differential acting on the diaphragm 30 is increased because of an opening 306, located mostly on the engine side of the throttle I4 (when the throttle I4 is in its idling position, as shown). This opening 306, which is in the shape of a narrow slot, communicates suction to the chamber 33 through the restriction 302 and the passage 30I.

All the other elements have numbers similar to the numbers in Figs. 1 and 2 and have the same function as before.

The slot 306, passage 304, restriction 302 and the passage 30I connecting the restriction 302 with the chamber 33 have the same function as, and replace the elements 20 and 24, spring 28 and the cap 26 in Fig. 1.

poses a load on the diaphragm 30. The fuel/ air ratio is thus increased at all positions of the throttle I4, but proportionately more at the lower" airfiows and high manifold suctions.

As the engine warms up the lever I00 rises as the element I I6 expands with a rise in temperature in passage H2. The load imposed on the diaphragm 30 by the spring 90 is thus reduced. The fuel/air ratio thus becomes progressively less as the temperature of the mixture in the inlet manifold II2 rises. The needle 42 in the restriction M, creates a pressure drop in chamber 52 which is opposed by the spring load 28 and 90 acting on the diaphragm 30. The throttle Hi, link 28, cam 2 engaging with cap 20, varies this spring load 28 as the throttle moves away from the idle position and at the same time opens the orifice 40 by withdrawing the needle 42. Meanwhile the air flow through venturi I2 is increasing and eventually an appreciable suction is built up in chamber 33 to supplement the spring load 28 and 90. The transition from idle to normal running is thus accomplished smoothly.

The normal operation of the carburetor is as follows: As the air flow increases the depression in the throat of venturi I2 is transferred to the chamber 33. The chamber 35, above the diaphragm 30 is in free communication with the air entrance I0 through the passage 32.

The fuel flow is from the pump which is designed to maintain approximately a constant pressure into the chamber 41. At wide open throttle the diaphragm I4 moves up under the influence of the spring (the suction in passage !6 no longer being able to hold valve 80 closed.) The fuel drop for a given fuel flow is less now that fuel flows through both restrictions 40 and I8.

In Fig. 2 the throttle lever rotates the shaft 220 and thus opens the throttle I4 from its closed position. The spring I2 is then compressed and acceleration fuel is ejected from the chamber 32 through the restricted orifice 83. The slot 208 then opens so that fuel flows freely from passage 20 to passage 203, to chamber 52 above the diaphragm 38.

The spring load on the diaphragm 30 from the spring 28 is reduced as the lever 228 is pushed up (counter-clockwise) by the link 230 and lever 232. The lever 232 is rotated by the shaft 220, the throttle lever and the control link 22.

The fuel entering at 48 flows through the chamber 41 below the diaphragm 38, through the restriction 40, through passages 204, I99 and 203 to the chamber 52.

Otherwise the operation of the device as shown in Fig. 2 is the same as the operation of the device as shown in Fig. 1

In Fig. 3 the operation is as before with the exception that when the throttle I4 is in the idling position (as shown) suction is imposed on the passage 304. This suction is greater than the suction in the venturi I2 as applied to the opening 34 so that the suction in chamber 33 is greater than it was before. On the other hand the needle 42 has entered the orifice 40 and thus the fuel/air ratio is maintained within the desired limits.

This arrangement, and the alternative arrangement shown in Figs. 1 and 2, insures that comparatively large forces are always acting on the diaphragms 30 and 38 so that the motion of the metering elements 31--54, as they move to regulate the fuel/air ratio in the idle range, are certain. If these elements 422024 or elements 42304 were omitted the forces acting on the diaphragms during idle would be too feeble to be effective. In that event some more arbitrary (that is more empirical) means would be used. The means shown although semi-empirical are also semi-automatic.

What I claim is:

1. A carburetor having an air entrance, a venturi therein, an air exit, a throttle valve therein, a fuel entrance, a chamber connected thereto, a diaphragm forming one wall of said chamber, a fuel exit from said chamber, a restriction in said fuel exit, a second fuel chamber on the other side of said diaphragm connected to said fuel exit, a fuel exit from the second fuel chamber, a metering valve therein, a second diaphragm, two air chambers one on each side of said second diaphragm, a passage'connecting the high pressure side of said diaphragm to the air entrance pressure, a passage connecting the low pressure air chamber to the throat of said air venturi, a mechanical connection from said first and second diaphragms to said metering valve, a small bypass leading from the low pressure side of said second diaphragm and terminating in the wall of the air exit in a slot which is so located as to be gradually transferred from the atmospheric side to the engine side of said throttle as said throttle is moved towards its idling position, a fuel metering valve connected to said throttle, said fuel metering valve being adapted to cooperate with the restriction in said first fuel exit so that the pressure differences acting on the fuel responsive diaphragm and on the air responsive diaphragm are both increased gradually as the throttle is moved towards its idling position. I

2. A carburetor having an air entrance, a venturi therein, an air exit, a throttle valve therein, a fuel entrance, a chamber connected thereto, a first diaphragm forming one wall of said chamber, a restricted fuel exit from said chamber, a second fuel chamber on the other side of said first diaphragm connected to said fuel exit, a fuel exit from said second fuel chamber, a metering valve therein, a second diaphragm, two air chambers one on each side of said second diaphragm, a passage connecting the high pressure side of said second diaphragm to the air entrance pressure, a passage connecting the low pressure air chamber to the throat of said air venturi, a mechanical connection from the first and second diaphragm to the fuel metering valve so that the drop in fuel pressure at said fuel restriction which acts on the first diaphragm just balances the air pressure drop at said air venturi which acts on the second diaphragm so that the air flow controls the flow of fuel, a movable abutment, a spring biasing the fuel metering valve to open position interposed between said abutment and the second diaphragm, temperature responsive means connected to the abutment so as to move it in the direction to increase the force exerted by the spring at low temperatures.

ANDREW WILLIAM ORR, JR.

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

UNITED STATES PATENTS Number Name Date 2,318,008 Morris May 4, 1943 2,389,219 Thompson et al. Nov. 20, 1945 2,390,658 Mock Dec. 11, 1945 2,392,055 Mennesson Jan. 1, 1946 2,447,791 Barfod Aug. 24, 1948

Images