US3005448A - Fuel injection system - Google Patents

Description

Oct. 24, 1961 T. M. BALL 3,005,443

FUEL INJECTION SYSTEM Filed Aug. 13, 1958 v 4/ f -.!f-' INVENTOR.

A 7/?4772'46 /y,54/Z

E a 7 BY W M Ma 3,005,448 FUEL INJE TION SYSTEM Thomas M. Ball, Bloomfield Hills, Mich, assignor to Chrysler Corporatiomllighlandflark, Mich, a corporation ofDelaware Filed Aug. 13,1958,- Ser.No.-754,766 11 Claims. ((31.123-119) This invention relates to fuelasystems for; internal combustionengineslandin particular to thetype disclosed in the related copendingapplication of ,ThomasM. Ball et al., Serial No. 75l,'999,--filed luly 3-0, 1958, and assigned to applicants assignee.

In fuel systems for internaltcombustionengines-which utilize fuel pressure responsive fuel metering means to supply metered fuel to .a rosette or fuel distribution chamber, the presencerof fuel vaporintheconduits of the system creates a serious'fuelsupply problem. Fuel vapor in the conduits occupying amuchlarger volume than liquid fuel, will cause a falseor synthetically produced pressure signal to be transmittedztowthe'aforementioned pressure responsive fuel meteringmeans and result in an erroneous adjustment-thereof. This erroneous adjustment necessarily causes an'incorrcct amount of fuel to flow to the engine. Moreover, fuel vapor in the distribution chamber prevents the chamber from properly distributing the metered liquid fuel in equal proportions to the several cylinders of the engine. This unequal distributionresults from the inability of the fuel distribution chamber distinguish between .vapor and liquid fuel and results in poor engine performance since some cylinders will be too rich in liquid fuel and other cylinderswill be too lean in liquid. fuelfor proper combustion eificiency and powerdevelopment.

The aforementioned fuel vapor is produced mainly during operating conditions of light engine load and high temperatures atwhich conditions the tendencyof the fuel to vaporize effectively exceedsits condensation tendency. By substantially increasing the pressure of the fuel in the lines of the system' and in the distribution chamber little fuel vaporwillfo-rm in the conduits regardlessiof the engine load and operating temperatures.

This increase in fuel pressure is'brought about herein bythe provision of a fuel nozzle which has an air bleed valve responsive to the existing manifold pressure to. control the pressure drop across-the fuel outlet of the system by increasing the fluid pressure immediately downstream of said fuel outlet. "The valve is designed to allow a greater air bleed at high vacuum manifoldconditions to offset the fuel drag out effect .Of alargepressure drop across said fuel outlet. This valve and air bleed are also designedto effect thedirect'impingement of the bleed air upontheifuel'flowing through theiiuel outlet so as to uti-lize the momentum of the airrnoleculesin further reducing the pressure drop across said fuel outlet.

An object of this invention is to providea fuel system for internal combustion engines which system operates at fue'l pressuresrsufiicient to avoideXcess-ive fuel vaporization within the conduits and pass-ages of said system during light load andhigh temperature operating conditions.

Anotherobject is ,ioprovidea fuel nozzle for use on fuel sy tte-msof internal -,combustion engines which is responsive to variations inthefuelrequirements of said engineto maintain the fuelpressure .within. said system sufliciently hig .Io preventusaid aforementioned fuel vaporization.

Patented Oct. 24, 1951 Another object is to provide a fuel, injectiounozzlefor usein :a fuel injection systemhavingia load metering portion, a speed metering portion, and a fuel distribution portion, which nozzle is responsive to variations in the fuel. requirements of said engine to maintain the pressure. of the fuel within said load metering portion, said speedmeteriug, portion, and said. fuel distribution portion of said system to prevent the aforementioned fuel vaporization.

.A further object isto provide an. effective means :to prevent the improper distribution of fuel to the separate cylinders of a multicylinder internal. combustion engine due to fuel vaporization withinthe fuel system-feeding said engine.

Further-objects and advantages will become apparent from the following specificationand dnawings, in-which FiGURE 1 represents a view partly in crosssection of the complete fuel injection system; and

' FIGURE 2 represents an enlarged view in-cross section of thenfuel injection nozzle shown in FIGURE 1.

In FIGURE liisshown -a=;fuel injection rneter-ingsysrem for an internal combustion engine 10, said engine having heads 12 and exhaust manifold banks 14 oneach head thereof, said metering system comprising a fuel speed metering unitld, a fuel load metering unit 18, and a fuel supply 20. 'Thefuel speed-metering unit l6-is provided with four housing portions 22, 24, 26, and 28 separated from each other by diaphragms '30, 32,- and 84 respectively to provide chambers 36, 38, 40, and 42. Chamber 36 communicates withfuel supply 20 through conduit 44. A fuel pump 46 in said conduit supplies a constant volume of fuel through filter 48 to chamber 36 during the operation of said engine regardless of the engine load or speed. A return flow metering orifice 50 in said housing portion 22 connects chamber 36 with-'a return flow conduit 52 which communicates with the inlet, check valve 54 of accelerator pump 30.

A return flow metering needle 56 having a'tapered point 58 is secured to each of said diaphragms '30, 32, and 34 by suitable-grommets 60.

A flyweight support 62 pivotally supportsflyweights 64 and 66 and is secured to a flexible shaft '68 journaled, in housing 28 and operatively connected to the engine 10 to rotate at a speed directly proportional to engine speed.

Flyweights '64 and 66 have projections 70 and 72 reto rotation of shaft 68 to urge needle '56 towardorifice 5.0 against the force applied in the opposite direction against diaphragm 30 by the fuel in chamber 36.

A conduit 74 connects chamber 36 to the upstream chamber 76 of the load sensor 18 which upstream chamber communicates with a downstream fuel distribution chamber '78 of the load sensor across a load metering orifice 80. A tapered load metering needle 82 having a tapered end 84-positioned in orifice is operatively connected to piston'86 reciprocably mounted in cylinder 88, which cylinder operatively communicates with each intake manifold on said engine through conduit 92. Low pressure transmitted through conduit 92 will cause piston 86 to be drawn upwardly against the force of spring 94 to thereby urge the tapered end of needle 82 into closer proximity to the sides of orifice 80 and conversely high pressure in the intake manifolds will tend to urge needle '82 to amore open position with respect to orifice 80. A plurality of nozzle feed conduits 9.6 extend from chamber 78 ofthe load sensor to an equal number of fuel injection nozzle 98 located downstream of the V 3 throttle valve 100 of the common intake manifold section 101. Chamber 78 of the load sensor is connected to chamber 38 of the speed sensor by conduit 112 to provide an adjustment of the return flow metering needle 56 with respect to orifice 50 based on the pressure differential existing across orifice 80 of the load sensor.

An idle boost conduit 114 communicates with said common manifold section 101 at a point adjacent the edge of the throttle valve 160 of that section and with the idle boost chamber 40 of the speed sensor. An air bleed valve 116 in conduit 114 is provided to regulate the pressure transmitted to chamber 40 from said manifold section during idling of the engine in order to regulate thereby the speed of the engine at idling. Under normal idling conditions the pressure in chamber 40 is lower than in chamber 42 which is vented to the atmosphere through orifice 115 and said pressure in chamber 42 tends to urge the needle 56 toward orifice 50 to retard the flow of return fuel therethrough and provide a sufficient fuel supply for idling. The requirement of this additional boost to needle 56 is due to the fact that at slow engine speed the flyweights are not flung outwardly with sufiicient force to negate the frictional resistance of the needle 56 to movement.

The operation of the fuel injection metering unit will be described in relation to a change in static engine operating conditions, that is, constant engine speed and load. Under said static operating conditions, the combined forces exerted by flyweights 64 and 66 and the fuel in chamber '38 is balanced by the force exerted by the fuel in chamber 36 and the return flow metering member 56 is maintained stationary at a distance away from orifice 50. In this static condition, the amount of fuel deliveredto the distributing chamber 78 is constant and is equal to the constant amount of fuel being delivered to the system by the pump less the constant amount of fuel being returned to the fuel tank through the return flow conduit 52. if this static condition represents the engine during normal driving speed, the pressure in chamber 42 has no noticeable efiect on the operation of the unit and may be disregarded. It is only during idling and very low engine speeds that the pressure differential across diaphragm 34 becomes significant.

As the throttle valve 1% is moved to a more open position by the depression of the engine accelerator, an increase in manifold pressure is transmitted to the load sensor piston through conduit 92 and moves said piston down to thereby move the load metering needle 82 to a more open position with respect to the load metering orifice 80. The pressure differential existing across said orifice is consequently decreased as more fuel is allowed to flow into chamber 78. This decrease in pressure differential causes the flow through orifice 80 to deviate from the desirable flow which is substantially directly proportional to engine speed. To correct this condition and bring the pressure differential across said orifice up to a value where the flow of fuel therethrough is substantially directly proportional to engine speed, the fuel pressure in fuel supply pressure chamber 36 and load sensor upstream chamber 76 communicating therewith is increased. This increase in pressure is accomplished by moving the return flow metering member 56 closer to orifice 50 by the increased force transmitted by the fly- Weights 64 and 66 as the engine speed is increased and by the increased pressure in chamber 38 caused by the increased flow of fuel into the downstream chamber 78 of the load sensor. When the forces transmitted by said flyweights and the fuel in said chamber 38 once again balance the force transmitted in the opposite direction by the fuel in chamber 36, the flow of fuel through orifice 80 will be substantially directly proportional to the speed of the engine and will correspond to the flow of air into the intake manifold.

Referring to FIGURE 2, nozzle 98 comprises a body 118 threadedly received at 119 in intake manifold 90 4 and having a recess 12%) adapted to receive nozzle feed conduit 96 and retain said conduit therein through frictional engagement therewith. The fuel outlet 122 of nozzle feed conduit '96 communicates with manifold through nozzle passage means or chamber 124 and primary fuel jet 126 in body 118. This primary fuel jet is sufliciently large to accommodate the required fuel flow to the engine at relatively low speeds and light loads, but, at high manifold pressure operating conditions a secondary fuel jet 128 in body 118 is opened by the movement of the adjustable pressure responsive sliding valve means 130 to the right in FIGURE 2. This movement of means 130 to the right is caused by high pressure in manifold 90 being transmitted through a manifold pressure passage or conduit 132 in body 118 to the chamber 134 and flexible diaphragm 136. The combined high manifold pressure and the pressure of spring 138 forces diaphragm 136 to the right into chamber 140 which chamber is vented to the atmosphere at 142. Chambers 134 and 140 are formed by diaphragm housing portions 135 and 141 secured together at their peripheries by suitable means 143.

An air bleed valve generally designated 144 is comprised of the two relatively movable parts body 118 and sliding valve member 130. Bore 121 of any convenient shape in body 118 slidably receives member 130 of a complementary shape with a suflicient side clearance to allow movement of member 130 in response to slight pressure variations in chamber 134. An air bleed aperture 146 in body 118 and an air passage 148 in member 130 allow an air flow to air jet 150 in the end of passage 148 when said aperture and passage become partially or fully registered with each other.

Registration of aperture 146 and passage 148 occurs when a low pressure exists in manifold 90 and is transmitted to chamber 134 and diaphragm 136 through manifold pressure passage or conduit 132 in body 118. When said registration occurs, the low pressure in manifold 90 will cause air to flow through 146, 148, and 150, and into chamber 124 in an amount proportional to the degree of said registration. This air flow will increase the pressure in chamber 124 to a value which will decrease the pressure drop across fuel outlet 122 and prevent excessive sucking. out of the metered fuel from conduit SP6 and distsribution chamber 78. Another effect of said air flow is that the air molecules flowing through jet 150 are directed against the fuel flow through outlet 122 and the momentum associated with said air molecules tends to force said fuel back into the conduit 96. The effect .of the reduction in pressure drop across the fuel outlet is a fuel pressure increase in conduits 96 and distribution chamber 78 which pressure increase prevents the fuel in said conduits and chamber from vaporizing and causing unequal distribution of metered fuel to the separate fuel injection nozzles 98 and also prevents erroneous adjustment of the fuel metering means as aforesaid.

It is noted that the sliding valve member 130 is advantageously used to control the flow of fuel through the secondary fuel jet 128 and the flow of air through air jet 150 and it is obvious that at certain manifold pressures both the jet 128 and the air valve 144 will be partially opened and partially effective to perform their functions.

I claim:

1. In a fuel injection system for an internal combustion engine having an intake manifold, said system having a fuel feed conduit for supplying fuel to said engine, a fuel injection nozzle adapted to be mounted in said manifold, said nozzle comprising a body having means thereon for receiving the fuel outlet end of said fuel feed conduit, fuel conduit means in said body operatively connecting said fuel outlet end to said manifold, adjustable air bleed means on said body communicating with the atmosphere and said fuel outlet end and operable to regulate the pressure drop across said fuel outlet end, and manifold pressure responsive means operatively connected to said air bleed means-andsaid manifold toaadjust-rsaidaair bleed means according to, manifold. pressure.

2. In a fuel system for a multicylinder internal combustiongenginelhaving separate, intake; manifold ;.p.ortions communi ating w h separate pylindfls .ofsaid engine, fuel e m ans cemmunicat nawith .said mani l PQYfiQIlS, -fue n z 'ineachisaid manifold-portion receiv nais i fuel feed means, each said nozzle having fuel feed pressure regulating means thereon responsive to engine intake pressure to reduce the excessive drag out of fuel from said fuel feed means caused by low intake pressure and to maintain sufficient pressure in said fuel feed means to prevent substantial fuel vaporization therein.

3. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel feed conduit connected to a fuel supply and communicating with said manifold, a fuel injection nozzle in said manifold receiving said conduit, said nozzle having fuel feed conduit pressure regulating means thereon to reduce the excessive drag out of fuel from said conduit caused by high intake manifold vacuum, and said pressure regulating means communicating with said manifold and being responsive to high vacuum therein to reduce said drag out.

4. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel feed conduit connected to a fuel supply and communicating with said manifold, said conduit having a fuel outlet, a fuel injection nozzle in said manifold receiving said fuel outlet of said conduit, said nozzle having a fuel jet communicating with said fuel feed conduit outlet through nozzle passage means, and an adjustable air bleed valve on said nozzle communicating with said nozzle passage means, said air bleed valve being connected to said manifold and responsive to pressure therein to regulate the flow of air through said valve to said passage means.

5. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel feed conduit connected to a fuel supply and communicating with said manifold, said conduit having a fuel outlet, a fuel injection nozzle in said manifold receiving said. outlet, said nozzle having a 'fuel jet communicating with said fuel feed conduit outlet through nozzle passage means, an adjustable air bleed valve on said nozzle communicating with said nozzle passage means, said air bleed valve being connected to said manifold and responsive to pressure therein to regulate the flow of air through said valve, an adjustable secondary fuel jet on said nozzle communicating with said nozzle passage means, an adjustable pressure responsive fuel valve means connected to said manifold and engageable with said secondary fuel outlet, and said pressure responsive fuel valve means being adapted to allow an increased fuel flow to the manifold in response to a corresponding increase in manifold pressure.

6. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel feed conduit connected to a fuel supply and communicating with said manifold, said conduit having a fuel outlet, a fuel injection nozzle in said manifold receiving said outlet of said conduit, said nozzle having a fuel jet communicating with said fuel feed conduit through nozzle passage means, an adjustable air bleed valve on said nozzle communicating with said nozzle passage means, said valve having an air jet disposed directly opposite said fuel outlet of said fuel feed conduit, and said air bleed valve being connected to said manifold and responsive to pressure therein to regulate the flow of air through said valve and said air jet.

7. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel feed conduit connected to a fuel supply and communicating with said manifold, said conduit having a fuel outlet, fuel metering means in said fuel feed conduit, said metering means having metered fuel pressure responsive means thereon adapted to adjust said metering means. and the fuel iiow therethrough in accordance with the --pressure of .said metered fuel, a fuel injection nozzle in .saidmanifold receivingsaid fuel outlet of :said conduit, and: said nozzle having. intake pressure responsive fuel pressure regulating means thereon communicating withsaid fuel outlet to reduce the pressure .dro-p'betweensaid fuel .out-let and-said manifold at high manifold vacuum to reduce the excessive drag out of fuel from said conduit.

8. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel feed conduit connected to a fuel supply and communicating with said manifold, said conduit having a fuel outlet, fuel metering means in said fuel feed conduit, said metering means having metered fuel pressure responsive means thereon adapted to adjust said metering means in accordance with the pressure of said metered fuel, a fuel injection nozzle in said manifold receiving said fuel outlet of said conduit, said nozzle having air bleed means thereon communicating with said fuel outlet of said conduit, and said air bleed means communicating with said manifold and being adjustable according to manifold pressure to reduce the excessive drag out of fuel from said conduit caused by high intake manifold vacuum.

9. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel feed conduit connected to a fuel supply and communicating with said manifold, said conduit having a fuel outlet, fuel metering means in said fuel feed conduit, said metering means having metered fuel pressure responsive means thereon adapted to adjust said metering means in accordance with the pressure of said metered fuel, a fuel injection nozzle in said manifold receiving said fuel outlet of said conduit, said nozzle having a fuel jet communicating with said fuel outlet of said conduit through nozzle passage means, and an adjustable air bleed valve on said nozzle having an air jet communicating with said nozzl passage means, said air bleed valve being connected to said manifold and responsive to pressure therein to regulate the flow of air through said air jet, said air jet being positioned directly opposite said fuel outlet of said conduit.

10. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel feed conduit connected to a fuel supply and communicating with said manifold, said conduit having a fuel outlet, a fuel metering valve in said fuel feed conduit, said valve having metered fuel pressure responsive means associated therewith adapted to adjust said metering valve in accordance with the pressure of said metered fuel, a fuel injection nozzle in said manifold receiving said fuel outlet of said conduit, said nozzle having a primary fuel jet communicating with said fuel outlet of said conduit through nozzle passage means, an adjustable air bleed valve on said nozzle communicating with said nozzle passage means, said air bleed valve being connected to said manifold and responsive to pressure therein to regulate the flow of air through said valve to said passage means, a secondary fuel jet on said nozzle communicating with said nozzle passage means, and an adjustable pressure responsive means connected to said manifold and communicating with said secondary fuel jet, said pressure responsive means being adapted to regulate the fuel flow through said secondary fuel jet and to allow an increased fuel flow to the manifold therethrough in response to a corresponding increase in manifold pressure.

11. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel feed conduit connected to a fuel supply and communicating with said manifold, said conduit having a fuel outlet, fuel metering means in said fuel feed conduit, said metering means having metered fuel pressure responsive means thereon adapted to adjust said metering means in accordance with the pressure of said metered fuel, a fuel injection nozzle in said manifold receiving said conduit, said nozzle having a fuel jet communicating with said outlet of said'fuel feed conduit through nozzle passage means, and an adjustable air bleed valve on said nozzle communicating with said nozzle passage means through an air jet, said air bleed valve being connected to said manifold and responsive to pressure therein to regulate the flow of air to said passage, said air jet being disposed directly opposite said fuel feed conduit outlet References Cited in the file of this patent UNITED STATES PATENTS Y Pringham Nov. 18, 1958

Images