US2988342A - Fuel injection system - Google Patents

Description

June 13, 1961 C. DERMoN-D 2,988,342

FUEL INJECTION .SYSTEM Filed March 24, 1959 4 Sheets-Sheet 1 I' A TTU/PNE? June 13, 1961 Filed March 24, 1959 4 Sheets-Sheet 2 INVENTOR.

June 13, 1961 1 c. DERMOND 2,983,342

FUEL INJECTION SYSTEM Filed March 24. 1959 4 sheets-sheet s INVENTOR.

ATTORNEY June 13, 1961 c. DERMOND 2,988,342

FUEL INJECTION SYSTEM Filed March 24, 1959 4 Sheets-Sheet 4 2,988,342 FUEL INJECTION SYSTEM Lawrence C. Dermond, Rochester, N.Y., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Mar. 24, 1959, Ser. No. 801,559 7 Claims. (Cl. 261-23) The present invention relates to a charge forming device for an internal combustion engine of the type in which a meter quantity of fuel is individually supplied to each of the engine cylinder induction passages proximate the cylinder intake valve. More speciically, the present invention is an improvement in the fuel injection system of the type shown in copending application Serial No. 591,889, Dolza, led June 18, 1956.

The present invention relates to an arrangement for maintaining the fuel system under pressure whereby the tendency of fuel to vaporize is reduced. Pressurzation of fuel systems is generally old, however, the present system relates to an arrangement whereby a continuous tlow fuel injection system may be pressurized.

The present invention in adapting a continuous ow fuel injection system to a pressurized system has resulted in the development of a unique nozzle device which insures accurate fuel metering irrespective of indiscriminate variations in supply pump pressure. Further, the present nozzle, though subjected to manifold vacuum, is constructed so as to be substantially insensitive to variations in such vacuum.

More particularly, the present nozzle is of the pressure responsive type in Which the metered fuel must exceed a predetermined value before fuel ow therethrough will occur. Fuel flow through the nozzle is uniquely controlled by a diaphragm the position of which is determined by the pressure drop across a fuel metering valve, the actuation of the latter being determined by certain engine operating requirements, eg., mass of induction passage air flow in the illustrated system.

`ln addition to the novel construction and operation of the pressure responsive nozzle, the nozzle diaphragm itself is of a unique configuration Which insures improved nozzle operation, particularly under low fuel flow conditions where difficulties have heretofore been encountered.

The details as well as other 'objects and advantages of the present linvention will be apparent from a perusal of the detailed description which follows.

In the drawings:

FIGURE 1 is an elevational view, partially in section, l

partially broken away and partially diagrammatic, illustrating the present invention in a fuel injection system;

FIGURE 2 is a plan view of the structure illustrated in FIGURE 1; t

FIGURE 3 is an enlarged sectional view of the air meter shown in FIGURE l;

FIGURE 4 is an enlarged sectional view of a fuel nozzle taken on line 4--4 of FIGURE 1;

FIGURE 5 is a plan view of the fuel nozzle of FIG- URE 4; i

FIGURE 6 is a section taken on line 6--6 of FIGURE 4; and

FIGURE 7 is a section through the nozzle diaphragm.

The fuel injection system with which the present invention has been illustrated is shown diagrammatically in FIGURE l and in greater detail in FIGURES 2 through 7.

The fuel system broadly comprises a manifold 10, an

air meter 12 mounted on the manifold and adapted to` supply air thereto, and a fuel meter 14 for supplying Patented June 13, 1961' metered quantities of fuel to the individual cylinder induction passages 16 extending from manifold 10.

Air is inducted through the air meter -12 where it passes into manifold plenum chamber 18 and distributed through the cylinder induction passages 16. In order to provide the requisite quantity of fuel to be mixed with the air inducted through air meter 10, an annular chamber or piezometer ring 20 is formed at the throat of a venturi 22 formed in air induction passage 24. A vacuum force proportional to the square of air ilow through venturi 22 is generated in chamber 20. A conduit 26 communicates with chamber 20 to transmit the aforenoted vacuum force to fuel meter 14 wherein fuel iiow is matched to air flow. The details of the fuel meter will subsequently be discussed in detail. Fuel from fuel meter 14 is delivered through a conduit 28 to a distributor 30, FIGURE 2, from whence the fuel is supplied through conduits 32 to fuel nozzles 34 associated with the respective cylinder induction passages 16.

In .the illustrated embodiment a pair of fuel nozzles is disposed in each of four nozzle bodies indicated generally at 34. It is to be noted that the number and design of nozzle bodies 34 is appropriate to an eight cylinder engine. The details of the `nozzle body construction will be subsequently considered in detail.

Referring again to air meter 12, a throttle 36 is provided for controlling the quantity of air ow through induction passage 24. -A linkage and lever mechanism indicated generally at 38 is suitably articulated to throttle valve 36 for controlling theopera-tion thereof. A conventional idle air bypass control valve is shown at 40 in FIGURE 2. The air meter, per se, constitutes no part ofV the present invention, accordingly, no further detailed j description thereof will be undertaken. i

Fuel meter 14 as best shown in FIGURES l and 3 will now be described and includes a casing 42 within which a fuel reservoir 44 is formed to'be supplied with fuel from any suitable low pressure pump, not shown. A pump 46 is disposed in reservoir 44 `and includes gear members 47 and 49. Pump 46 is adapted to be driven through a shaft 48 .by any suitable engine accessory drive mechanism. Pump 46 supplies fuel under pressure to a fuel metering valve 50 through a passage 52 formed in pump casing 42.

Fuel metering valve 5t] is disposed in casing 42 and includes an outlet coupling 54 through which metered fuel is supplied` to conduit 28. Metering valve :S0 comprises a valve seat member S6 enlarged at its upper endto provide a spherical seat for a ball valve member 58. Ball valve 58 is retained in a movable relationship upon seat 56 by a suitable retaining ring 60. Fuel supplied under pressure to valve chamber 62 from pump 46 tends to lift ball valve member 58 olf of its seat permitting fuel to be bypassed back to pump reservoir 44. The extent to which valve 58 may lift off of its seat is determined by an arm member 64 in turn controlled in accordance with to the full extent permitted without limit by retainer` ring 60.

Casing 42 includes an enlarged portion 66 adapted to be enclosed by a cover 68 which peripherally clamps a i `diaphragm 70 thereto. Casing 42 and diaphragm 70 deiine a chamber 72 which is communicated with venturi vacuum conduit 26. Thus the left side of diaphragm 70 is exposed to the vacuum force generated by air flow past piezometer ring 20. Diaphragm 70 and cover casing 72 define a chamber 74 which is subjected to the impact pressure of air ow through air meter 12 by a conduit 76 which communicates with the air meter anteriorly of throttle 36. Thus, as air ow increases through air meter 12 venturi vacuum in piezometer ring 20 likewise increases tending to move diaphragm 70 to the left which movement, as will be seen, increases fuel How.

Metering valve control arm 64 is xed to a pintle member 78 which extends through an opening 80 in casing 42 and is pivotally mounted therein by an O-ring member 82. O-ning 82 not onlyy permits pivotal movement of pintle 78 but also seals vacuum chamber 72 from the reservoir 44. An arm 84 is fixed to the other end of pintle 78 `and extends upwardly within vacuum chamber 72.

A stud member 86 is slidably mounted within casing 42 and includes a lever 88 articulated to the upper end thereof. Lever 88 in turn supports a stud member 90, one end of which engag arm 84 intermediate its ends. The other end of stud 90 engages a lever 92 loosely articulated from a bracket 94 formed in casing 42. Lever 92 includes a projection 96 which engages with a rein'- forcing washer 98 centrally mounted on diaphragm 70. A recess 100 is formed in casing 42 and provides a seat for a spring element 102 urging arm 84 into engagement with stud 90. A recess 104 is also formed in cover` casingf68 and in turn provides a housing for a spring member 106 which biases diaphragm 70 in a leftwardly direction. Spring 106actual1y seats on a washer member 108 which is fixed to a threaded member 110 permitting external adjustment of the spring for regulating the basic setting of the fuel metering valve.

Thus with the parts in the position shown in FIGURES 1 and 3', an increase in vacuum Within chamber 72 will causeV a leftward movement of diaphragm 70 occasioning a similar movement in stud 90 ycausing arm 84 to impart a counterclockwise rotation to arm 64. Ball valve member 58 is thereby moved toward seat 56 reducing the amount of fuel being bypassed to the pump reservoir 44 `and thereby increasing the quantity of fuel supplied to nozzles 34. Correspondingly a decrease in air ow through the air meter will occasion an increase in the absolute pressure in chamber 72 permitting spring 102 to cause arm 64 to move away from ball valve member 58 bypassing more fuel and thereby decreasing the quantity of fuel supplied to the nozzle.

To provide for enrichment of the fuel-air ratio under high power demand conditions, a power enrichment mechanism 112 is provided. Mechanism 112 includes a casing portion 114 enclosedv by a cover casing 116 which peripherally clamps a diaphragm member 118 thereto. Chamber 120 delned by diaphragm 118 and casing 116 communicates with a conduit 122, the other end of which connects with -manifold plenum chamber 124. Stud 86 is centrally ixedto diaphragm 118 and is urged in an upwardly direction by a spring` element 126 seated within casing 116. Under normal operating conditions, manifold vacuum will be of a sufficiently high magnitude to overcome spring 126 to move diaphragm 118 downwardly against an adjustable stop 128 as shown in FIGURE 3. However, upon the sudden opening of throttle 36, indicative of increased power demand, manifold vacuum in chamber 120 will decrease sufficiently to permit spring 126 to move diaphragm 118 and stud 86 upwardly thereby sliding stud member 90 upwardly with respect to` lever 84. This upward movement of stud 90 relative to lever 84 increases the moment arm through which the force of diaphragm spring 106 is transmitted to arm 64 thereby increasingthe rotationof said As a result, ball valve member 58 will be retained closer to seat 56 thereby increasing the quantity of fuel supplied to nozzles 34, supra. As the engine returns to normal operation, manifold vacuum will again increase to a value suicient to return the diaphragm to its lowermost or economy position as shown i-n the drawings.

As already noted, nozzle bodies 34may be varied in numbers and in groupings in accordance With the number of cylinders of the engine on which the present fuel injection system is embodied. In the illustrated form of the invention, a pair of nozzles 13G is formed in each nozzle body 34, as best seen in FIGURES 4-6. Nozzle body 34 includes a iirst or lower casing member 132 from whence nozzles 130 extend. Referring now to FIG- URES 4 and 6 it will be seen that an` inlet opening 134 is formed in casing 132 and 'communicates with a longitudinally extending passage 136. A pair of transversely extending passages 138 and 140 branch from passage 136. An adjustable metering pin 142 is disposed in each of the transverseV passages and includes a tapered needle portion 144 which coacts with a reduced portion 146 of each of the passages to establish the basic fuel ow rate through the nozzle. A second casing member 148 is provided and is adapted to be secured through suitable means 150 to casing 132.

Casing 148 includes an inlet 152 communicating with a longitudinally extending' passage 154 connecting with a pair of transversely extending passages 156 and 158. Transverse passages 156 and 158 each terminates in Van enlarged or recess portion 160 and 162 adapted, respectively, to overlay the corresponding subadjacent transverse passages 138 and 140 of casing 132.

A flexible diaphragm 164 is peripherally clamped between casings 132 and 148 and, as will subsequently be considered in greater detail, is adapted to be moved by a pressure differential thereacross to permit meter fuel to flow from the transverse passages 138 and 140 of casing 132 underneath the diaphragm and to be discharged through nozzle passages 166.

Inlet 134 of nozzle 'casing 132 connects with conduits 32 and 28 which are supplied with metered fuel from metering valve 50. Inlet 152 of cover casing 148 communicates through a conduit 168 with an outlet tting 170 disposed in an opening 172 in fuel reservoir 44. Thus the pressure in 'conduit 168 will be at a lower value than that of the metered fuel pressure in conduit 28 since a pressure drop will occur as fuel is bypassed to reservoir 44 through metering valve 50. Accordingly, under normal operating conditions, a pressure diierential will exist across diaphragmv 164 whereby the metered fuel pressure will raise the diaphragm within the recesses 160 and 162 of casing 148 permitting metered fuel to flow from transverse passages 138 and 140 to nozzle discharge passages 166. Upon shutting oiii the engine, the fuel pressure in reservoir 44 will act on the upper side of diaphragm 164 to block iiow out of nozzle passage 166 thereby preventing fuel from draining from the fuel system.

Diaphragm 164 being responsive to the fuel pressure on the discharge or low pressure side of metering valve 50, as well as to metered fuel pressure, leaves the nozzle fuel flow unaffected by variations, eg., pulsations, in pump pressure. Thus a pulsation in pump pressure would be impressed across both sides of diaphragm 164 leaving the metered fuel unaffected.

The construction of the diaphragm nozzles constitutes an important aspect of the present invention and will now be considered in further detail. The structural relationships between diaphragm 164 and surface 174 of casing 132 with which it coacts are critical and the present members have been designed in such a Way as to insure proper nozzle operation.

It is to be noted that the operation of such a nozzle is particularly critical under low fuel ow conditions such as occur during engine idling, where an inability of the diaphragm to suitably restrict fuel ow will cause ilooding. On. the other hand, an inadvertent complete closing by the diaphragm would starve the associated cylinder of fuel. i

It is found that if diaphragm 164 is made with a smooth surface there is a tendency for the diaphragm toV lock shut on surface 174, particularly after the engine has been shut down and restarting is attempted. It is found by making the face of diaphragm 164, cooperating with surface 174, with a controlled roughness the vacuum locking of the diaphragm is avoided.

It s also found, however, that indiscriminate roughing of the diaphragm surface cannot be undertaken. If the surface is too rough the diaphragm is unable to reduce or stop fuel flow during idle operation or when the engine is shut oif. On the other hand, if the surface is not rough enough locking will occur.

A considerable problem was experienced in controlling the roughness of the diaphragm surface and maintaining the same within tolerances. This has been done by curing the sheet rubber, from which the diaphragm is to be made, while held against a rather fine weave textile such as silk cloth. Thereafter, the rubber sheet and cloth are separated leaving the weave impression on the rubber as seen in FIGURE 7. By using a silk fabric having a cloth weave count generally within the range of 68 x 64 per square inch and 100 x 100 per square inch, a satisfactory diaphragm roughness is achieved and the nozzle will function properly.

An additional advantage of utilizing a roughened diaphragm surface made as already described, is the realization of a nonfouling diaphragm. Again during low fuel flow conditions diaphragm 164 may be substantially closed under which circumstance fuel will flow through the Various paths defined by surface 174 and the grooves in the roughened surface of diaphragm 164. As any of these flow paths become obstructed due to dirt particles, the fuel seeks out another such path and ow continues unabated.

I claim:

l. A charge forming device for an internal combustion engine comprising an air intake system including a plurality of individual induction passages for each of the cylinders of the engine, a fuel nozzle disposed in each induction passage proximate the associated cylinder, and means for supplying metered quantities of fuel to said nozzle, said means including a fuel reservoir, a pump disposed in said reservoir, a common fuel metering valve, said pump being adapted to supply fuel under pressure to said metering valve, said metering valve including a pair of outlets, one of said outlets being adapted to supply fuel to said nozzles, the other of said outlets communicating with said reservoir, a valve element coacting with said other outlet to control the quantity of fuel under pressure bypassed to said reservoir, and means for controlling the position of said valve element to vary the position thereof in accordance with engine demand whereby the quantity of fuel bypassed to the reservoir decreases with increases in engine demands, each of said nozzles including a metered fuel inlet passage and a discharge passage, diaphragm means intermediate said nozzle inlet and discharge passages, and means for impressing the pressure differential across the metering valve element across said diaphragm whereby the quantity of metered fuel discharged from each nozzle is determined solely by the means for controlling said metering valve.

2. A charge forming device for an internal combustion engine as set forth in claim l in which said nozzle comprises rst and second casing means, a Afuel inlet in said rst casing means, a conduit communicating said inlet with the first outlet of the fuel metering valve, the diaphragm means being peripherally clamped between the first and second casing means, a rst passage in said rst casing means communicating with the fuel inlet, said first passage terminating adjacent said diaphragm, a second passage formed in said first casing terminating at one end adjacent said diaphragm and adapted to discharge metered fuel to the associated induction passage, a fuel inlet formed in said second casing means, a passage formed in said second casing means and communicating at one end with said fuel inlet and terminating at its other end adjacent said diaphragm on the opposite side thereof from said first and second passage means of the rst casing means, a conduit communicatng the inlet for the `second casing means with said reservoir.

3. A char-ge forming device for an internal combustion engine comprising an air intake system including a plurality of individual induction passages for each of the cylinders of the engine, a fuel nozzle disposed in each induction passage proximate the associated cylinder, and means for supplying metered quantities of fuel to said nozzle, said nozzle comprising casing means, a flexible diaphragm peripherally supported within said casing means, fuel inlet and outlet passages in said casing means, the inlet and outlet passages each including an end terminating in a ilat surface disposed proximate the same side of the diaphragm, the diaphragm coacting with said sur face to control fuel flow between said passages.

4. A charge forming device as defined in claim 3 in which the said same side of the flexible diaphragm comprises a roughened surface to prevent the diaphragm from blocking fuel flow under low `fuel demand conditions.

5. A charge forming device for an internal combustion engine comprising an air intake system including a plurality of individual induction passages for each of the cylinders of the engine, a fuel nozzle disposed in each induction passage proximate the associated cylinder, and means for supplying metered quantities of fuel to said nozzle, said means including a fuel reservoir, a pump disposed in said reservoir, a common fuel metering valve, said pump being adapted to supply fuel under pressure to said metering valve, said metering valve including a pair of outlets, one of said outlets being adapted to supply fuel to said nozzles, the other of said outlets communicating with said reservoir, a valve element coacting with said other outlet to control the quantity of fuel under pressure bypassed to said reservoir, and means for controlling the position of said valve element to vary the position thereof in accordance with engine demand whereby the quantity of fuel bypassed to the reservoir decreases with increases in engine demands, each of said nozzles including a metered fuel inlet passage and a discharge passage, diaphragm means intermediate said nozzle inlet and discharge passages, and means for impressing the pressure differential across the metering valve element across said `diaphragm whereby the quantity of metered fuel discharged from each nozzle is determined solely by the means for controlling said metering valve, said nozzle comprising casing means supporting said diaphragm, fuel inlet and outlet passages in said casing means, the inlet and outlet passages each including an end terminating in a at surface disposed proximate the same side of the diaphragm, the said same side ofthe diaphragm. coacting with said flat surface to control fuel ow between said passages.

6. A charge forming device for an internal combustion engine as set forth in claim 1 in which said nozzle comprises first and second casing means, a fuel inlet in said first casing means, a conduit communicating said inlet With the first outlet of the fuel metering valve, the diaphragm means being peripherally clamped between the first and second casing means, a first passage in said first casing means communicating with the fuel inlet, said first passage terminating in a planar surface adjacent said diaphragm, a second passage formed in said first casing terminating at one end in said planar surface and adapted to discharge metered fuel to the associated induction passage, a fuel inlet formed in said second casing means, a passage formed in said second casing means and cornmunicating at one end with said fuel inlet and terminating at its other end adjacent said diaphragm on the opposite side thereof from said first and second passage means of the first casing means, a conduit communicating the inlet for thesecond casing means with said reservoir, Vthe side of the diaphragm adapted ,to coact with said planar surface being roughened Lto prevent the diaphragm from blocking fuel ow undef igwiuel demand conditions.

7. A charge forming device as set forth in claim 4 in which the roughened diaphragm side comprises a line pattern within the range of 64 x 68 to 100 x 100- lines per square inch.

References `Cited in the le of this patent l UNmeD STATES PATENTS Mock ....V.`. Ian. 14, 1947 -Do1za et al. Mar. 24, 1959 McDue July 7, 1959 Dennond et al. Aug. 4, 1959

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