US2382625A - Manifold injection carburetor - Google Patents

Description

Au@ 14, 1945- o. L GARRE-rsoN MANIFOLD INJECTION CARBURETOR Filed Hatch 19, 1942 lla mvENToR owen LfGARREr N A mi I l f.. v lMB/Y.

Patented Aug. .l4, 1945 2,382,625 MANIIFOLD NJECTN 'CARBURETOR Owen L. .Garretsom Detroit, Mich., as'sgnor to Phillips Petroleum Company, a corporation of Delaware a i siam.

' invention relates to a method of fuel injeci tion in internal combustion engines; and to appalresortto positive displacement piston-type injectors which' are common to pastI devices. The

yuse of c-operated injector pumps |in previous devices has required a modification of the structure of the engine promr, whereas my device may be applied to the manifold of any standard gas engine. My device has a further advantage over conventional charge-forming devices in that the Venturi tube and the main th'rottle valve are the only major parts which need be attaoh'ed directly to the engine manifold. All the fuel control elefments may be placed at a reasonably remote point by suitable extension of the tubing connections leading to the engine manifold. VThus, all the adinstable moving par-ts, exceptthe throttle itself, may be placed wherever they will -be most accessible for adjustment or repair. f5

My invention has for its main objectv the ac-v complishment of direct fuel injection to the var'- ious manifold branchesof a gas engine by means directly controlled bythe engine air intake.

It is a further object to attain the above 'function with the minimum of parts and at the least expense of manufacture.

vAnother object is to provide the inherent ad- .vantages ofldirect manifold-injection in an embodiment which lcan be applied V4to standard; en gines without modification of the latter. An important object is to permit installation of the fuel control device at an accessible location,

, In the drawing, the numeral I denotes the intake manifold riser of an internal combustion engine in which the branches 2 are provided for `distribution of air and fuel to the various cylinders of the engine in the customary manner. In mydevice, however, the fuel is introduced by means of individual nozzles 3, located in each of the aforementioned branches, the nozzles receiving their fuel Vthrough branches emanating from a common fuel line 4.

The flow of fuel in the line 4 is controlled by the' fuel governor indicated 'generally by the numeral 5, fuel being conducted to the latter, under pressure, through' the inlet line 6 from the supply source (not shown). x

The fuel governor has the upper and lower diaphragms l and 8, respectively, which are mounted on a common sterir 9, and attached to the latter part is a valve disc I0 whichis thus responsive to the motion of the two diaphragms. `By virtue of theJ two diaphragms, the upper portion of the fuel governor is divided into two chambers I I and I2; the lower portion is likewise divided into two 'chambers I3 and I4. A bushing I5 is pressed into the structure so as to separate the chamber I2 fromgchamber I3, and is provided with an opening to receive the stem 9, This opening is reamed l to a close yfit with the stem, the clearance being lnozzle I 6 for'the valve disc I0, whichI together form a throttling valve controlling the fuel ow.

' The vupperend of the nozzle `channel is restricted so as to form aguide I 'I for the valve stem 9. This guide serves only 'to center the disc II) coaxially with respect to the nozzle I6, and has no pressurewhereas other devices must practically always be mounted directly on th'e manifold intake riser, re

gardless loi the convenience.v or inconvenience of such a location It is also an important obiect to permit -use of/a.

wide range fuels by simple adaptations of thejuel line pressure and manifold Jet size to accommo- 'j este them.`

The advantages of positive pressure fuel iniection to an engine manifold are per se well sealing function as in the case of the upper guide I5. One or more openings I8 `are provided to comthe upper end of the stem 9. In Itheform of known, and a complete recitation of them here wouldbesuperuous.

my device herein illustrated,- I prefer to use a tension spring here, in which case` the disc IIl would be urged toward the nozzle I6 and the mainfucl, valve would thus be heldl closed when the engine is not running. -A screw I9 is provided for adjustment of the tension spring'.` Obviously the degree of tension or compression on spring I8A will depend on the particular installation and relative size of the diaphragms 'I and 8.

A pressure conduit communicates from the chamber I3 to a point below the main throttle 2| in the manifold riser. A second pressure conduit 22 communicates between chamber I2 and 'a restricted venturi section 23 in the manifold riser. A third pressure conduit 24 connects the chamber II to the riser I at a point on the air inlet side of the venturi. An idle fuel line 25 by-passes the main governor valve, and is fitted with an adjustable needle valve 26 In operation, liquid hydrocarbon fuel (preferably) is supplied under pressure through the line 6, the pressure being provided by an enginedriven fuel pump, or other means, not shown. Assuming the throttle II to be substantially closed and the engine running at idling speed, a high degree of suction will exist inline 20, and the pressure in lines,22 and 24 will be substantially atmospheric. As a result, the dominant force on the governor mechanism will be the upward-acting force on the lower diaphragm 8 due to the suction in line 20 and chamber I3. Hence the valve I0 will be closed tightly, and fuel will enter the engine manifold only by virtue of the by-pass line 25. The needle valve 26 is adjusted to pass the required fuel for good engine idling.

Upon opening of the throttle, the pressure in line 20 and chamber I3 will rise. At the same time, the flow of air will be accelerated through the venturi 23, and a suction will be induced in line 22 leading to chamber I2. A downward force will hence be generated on the large diaphragm l. This downward force, due to proper propor- -tioning of sizes of the diaphragms, will begreat enough to overcome the now diminished upward force on diaphragm 8, resulting in opening of valve I0 and an additional flow of fuel under pressure of the fuel pump will-occur through the line 4 and the nozzles 3. As valve`l0 opens, the pressure in chamber I4 increases to a. point sufequilibrium so established. The proper air fuel ratio at this running condition can easily be -obtained by proper sizing of the jets 3, and a fine adjustment lis .also provided by the spring IBA and the screw I9. Having once established the proper relationship of diaphragm, main fuel valve and nozzle sizes, and having made the proper final adjustment of the spring, the maintenance of any desired constant air-fuel ratio is automatic.'

, The quantity of air passing the throttle plate for'anv given degree of opening is dependent upon the pressure differential across the throttle. Upon analysis of the above-described mode of operation of the fuel governor, it is obvious that the main fuel flow is also in proportion to the same differential (i. e'. the difference in pressures in lines 20 and 22), and hence the air-fuel ratio is maintained at a substantially constant value so far as the main fuel is concern It is realized that the 'by-pass line 25 is not directly governed by the air differential, and may range of the engine, however, even the by-passed ,ficient to balance the force system, and the valve g will come to a position determined by the new` be in proportion to engine speed. Moreover, the by-pass line 25 could be eliminated by providing an adjustable stop on the main fuel valve stem, so that it could always be maintained sufficiently open to pass the required fuel for idling.

By proper design of the spring IIA, any desired air-fuel ratio characteristic can be developed. -For example, 'if a particular orifice chosen for the fuel jet 3 had the characteristic of varying as to coeillcient of flow discharge (as most orifices actually do), then the air-fuel ratio would be influenced accordingly at various engine speeds. By selecting a spring of proper rate, this. deviation from a constant mixture ratio could be modified to suit the requirement at hand. In many cases, a variation of mixture ratio is desired at different speeds.

Other possible modifications in the matter of fuel governing are obviously afforded by my device. The rate of response to varying pressure conditions can be regulated by providing needle valves or other restrictions in the lines 20 and 22. Moreover, the pressure differential between these two lines could be adjusted by connecting the lines together at some point between the manifold riser and the governor and installing an adjustable restriction in the connecting line. Further, the distribution of fuel to the various cylinders can be compensated to suit the manifold flow characteristics by Calibrating the fuel jets and thus obtaining perfect distribution of the total' fuel charge among the various cylinders. Pressure drop in the fuel line leading to the various jets could be compensated in the same manner.

The line 24 is provided simply to insure that the top of the diaphragm 'I will always be sublected to the inlet air pressure, and thus the effect of air cleaner resistance or other disturbing influences will be nullified. This line is desirable but not necessary tion.

It is to be understood that I do 'not limit my device to any particular fuel. High or low vapor pressure liquid fuels, or high pressure vapor-- form fuels could be accommodated by proper proportloning of the fuel pressure, the diaphragms sizes, and the fuel valve and jet sizes. In the case of low pressure liquid fuels, a fuel pump would serve to provide the injection pressure. In the case of high vapor pressure liquid or vapor fuels, a pressure reducing regulator could be made to serve in place of th`e fuel pump. The

-only requirement vital to operation of the sysposition of the particular fuel.

tem is that the fuel be supplied to the control I valve at a pressure high enough to afford control by throttlingthe `fuel pressure through the valve, and that the residual pressure after throttling will be high enough to afford positive injection into'the manifold.

1 There are of course certain additional requisites of a practical nature. For example,'if liquid fuels are used, vapor lock must be prevented by maintaining the pressure on the fuel at a relatively high level, depending upon the com- Conversely, in

` using a vapor phase fuel, care must be taken to idling fuel will not disturb the overall. air-fuel v ratio, since the airflow throughthe -manifold and the fuel flow through the line 25 will both.

avoid condensation of the vapor due to using fuel pressures in excess of the ldew point pressure at the lowest temperature to be encountered.

These are factors which can be controlled or of heat, etc. The refinements necessary to prf.

'to the operation of my invenhousings being separated from each other, resil.

vide satisfactory operation will vary, therefore,v in accordance with the fuel selected and the selection of the fuel and the rened form of my device are matters simply of engineering and mechanics. w

I recognize that my device is most easily adaptable to ordinary gasoline fed to the system by means of an engine-driven fuel pump, but this is only a preferred adaptation, and other fuels are usable in view of the discussion set forth above. r

I claim:

In a fuel system for an engine having an intake manifold, a source of fuel under pressure,

Aa fuel supply pipe connecting said source with the intake manifold andy including at least one metering orifice opening into the manifold, an air inlet communicating with the intake manifold having a venturi and/throttle therein downstream of said venturi, the improvement comprising a fuel control device including a valve in said supply pipe controlling the ow of fuel to the intake manifold, said valve having a stem connected to a lower diaphragm and an upper diaphragm, a iirst and a second housing. the upper diaphragm dividing the first housing into two chambers and the lower diaphragm dividing the second housing into two chambers, said lent means in the upper chamber of the first housing urging the valve closed, a pipe connecting the lower chamber of the-mst housing with the venturi section and being at the same pressure as the venturi section, a pipe connecting the upper chamber of the rst housing with the air inlet pipe upstream of the venturi sec tion, the diaphragm of the iirst housing being responsive to suction induced by kincreased ,air now through the venturi section which results in a higher pressure in the upper chamber oi the ilrst `housing' than'in the lower chamber of the rst housing to open the valve against the force of the resilient means, a pipe connectingthe'upper chamber of the second housing with the air inlet downstream of the throttle and said mf ber being under suctiony upon decreased air now through the venturi by closing of the throttle valve, the lower chamber of `the second housing communicating' with the fuel supply pipe when said valve is open, said resilient means closing said valve under the unstable conditions existing when the throttle is in idling position, and a fuel idling connection around said valve to byfuelY from said source to said oriice when said valve is closed. y

OWEN L.

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