US2898096A - Fuel injection system - Google Patents

Description

L. c. DERMOND ET AL 2,898,096

Aug. 4, 1959 FUEL INJECTION SYSTEM 3 Sheets-Sheet 1 Filed March 25, 195'? v' r n r IN VE N TO R s dime: 6230/? d ZZ z/mw flmmc A T TORNEY Aug. 4, 1959 Filed March 25, 1957 c. DERMOND ETAL 2,898,096

FUEL INJECTION SYSTEM 3 Sheets-Sheet 2 VIIIIIII/{I/IIIIIII MMI INVENTORS A TrO/e/VE y 7 Filed March 25, 1957 L. c. DERMOND ET AL 2,898,096

FUEL INJECTION SYSTEM I5 Sheets-Sheet 3 INVENTORS ATTORNEY United States Patent F 2,898,096 FUEL INJECTION SYSTEM Lawrence C. Derm ond and Elmer Olson, Rochester,

N.Y., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application March 25, 1957, Serial No. 648,100

3 Claims. (Cl. 261-37) The present invention relates to a fuel injection system and more particularly to an improvement in such system in which the fuel metering function is rendered substantially insensitive to changes in atmospheric temperature and pressure.

It has been found in fuel inject-ion systems and particularly of the type shown in copending application Serial No. 608,797 Olson, filed September 10, 1956, that under certain operating conditions changes in atmospheric temperature and pressure have affected the fuel metering operation to an extent causing engine stalling. This stalling has been traced to pressure changes within the metering systemoccasioned by high ambient engine temperatures as well as by altitude changes. It was discovered that when engines utilizing the subject type fuel injection sys tem were .idled under conditions when the ambient temperatures were relatively high or when operating the vehicle in high altitudes, that the engine after idling for a short period would stall and which stalling was traced to an over-enrichment of the idling mixture. Further analysis of the problem led to the discovery that under the conditions noted, the pressure above the fuel level in the fuel reservoir increased sufliciently to shift the fuel metering valve to a position increasing the quantity of fuel delivered to the cylinders beyond the latters ability to utilize the'sarne and hence resulted in the engine stallin due to fuel flooding.

The present invention has eliminated this problem by providing a mechanism whereby a substantially constant pressure is maintained above the fuel level in the fuel reservoir irrespective of changes in atmospheric temperature or pressure. Specifically, this salutary result has been achieved by communicating the fuel reservoir with a very low vacuum force which eliminates fuel vapors from the reservoir and yet which is of a sufficiently low value as not to interfere with the normal fuel metering operation of the system.

A detailed description of the invention is set forth in the appended specification and claims.

In the drawing: v

Figure l'is a partially sectioned view of a fuel injection system employing the subject invention;

Figure 2 is a partially sectioned enlargement of the fuel metering system per se; and

Figure 3 is a partially sectioned view of the induction passage.

The fuel control system, per se, is shown and described in copending applications Serial No. 608,797 01- son, filed September 1956, and Serial No. 608,853 Dolza, filed September 10, 1956 now Patent No. 2,843,098 granted July 15, 1958. Therefore, the system will only be described in such detail as is necessary to illustrate the present invention. An air induction passage is shown at 10 and includes a venturi portion 12 posteriorly of which is mounted a throttle valve 14 adapted to control the quantity of air flowing through the system. The air induction passage communicates with a manifold or 2,898,090 Patented Aug. 4, 1959 ice plenum chamber 16 from which a series of ram pipes 18 communicate with the individual cylinders of the engine. Fuel is supplied to the individual ram pipes through nozzles '20. Fuel is supplied to the individual fuel nozzles through passages 24 emanating from a fuel manifold 26 which is in turn supplied with fuel through a passage 28 leading from a metering device indicated generally at 30.

The fuel supplying and metering device 30, as shown in Figure l, is mounted in a housing which includes a case 32 and a cover 34. A conduit 36 is formed in cover 34 and is supplied with fuel from a low pressure make-up pump, not shown. A float controlled valve mechanism 38 is also disposed in cover 34 and communicates with conduit 36 through a passage 40 to which filtered fuel is supplied in accordance with the vertical position of the valve member 38 as determined by the position of a pivoted float actuated arm 42. In the normal manner, as float 42 is raised and lowered the valve 38 will shut off or admit fuel into a fuel reservoir 44 provided in casing 32.

A constant displacement type pump 50 which is driven at engine speed is mounted in the fuel reservoir and is adapted to pump fuel from the reservoir 44 to a conduit 46 leading genereally to a metering chamber 48.

Chamber 48 is separated from the fuel reserevoir 44 by a perforated partition 51. A bore 52 is formed in the casing of chamber 48 and is adapted to support therein a fuel metering valve 54, the details of which are described in the aforementioned copending application Serial No. 608,853 Dolza. Suffice it to say that conduit 46 supplies fuel to a chamber 56 defined by valve 54 and a removable plug 58. The fuel passes from chamber 56 through a central conduit 60, formed in a slidable plug portion 62 of the valve 54, to a ball check valve 64 seated upon the upper end of the plug 62. Valve 64 blocks the how of fuel through conduit 60 with a force determined by the rate of a spring ,66 Which presses upon the valve. The metering valve 54 also includes a cylindrical sleeve 68 having a plurality of circumferentially disposed ports 70 therein which communicate the fuel flowing around ball check valve 64 to an annularly relieved portion 72 of sleeve 68. The annularly relieved portion 72 communicates with a passage 74 in the casing wall into which is threaded an adapter plug 76 connecting with the fuel manifold supplying conduit 28. 4

Sleeve 68 also has a set of peripherally disposed bypass or spill ports 80 above the ports 70. Ports 80 communicate the interior of sleeve v68 to the chamber 48 and thence through a suitable passage back to the fuel reserevoir 44. To control the quantity of fuel bypassed through valve 54 back to reservoir 44 and hence the quantity of fuel supplied to the fuel nozzles, a cylinder 82 closed at the upper end is slidably mounted in sleeve 68. The open end of cylinder 82 terminates proximate spill ports 80' in sleeve 68. Fuel pressure within the valve body and which, as noted, is proportional to engine. speed tends to move the cylinder 82 upwardly to open ports 80 and thereby bypass fuel to the reservoir.

A linkage mechanism indicated generally at and controlled by a diaphragm 92 exerts a force on top of the valve, as generally described in the aforementioned copending application Serial No. 608,853, which is proportional to the quantity of air flowing through the system. Thus it will be seen that the quantity of fuel supplied to the nozzles 20 by metering valve 54 is proportional to the differential effect of engine speed, as manifested by fuel pressure, and the quantity of air flowing through the system, as manifested by vacuum acting on diaphragm 92.

In order to insure fuel air mixture enrichment is available when the engine is cold, an enrichment device indicated generally at 100 is provided. The actuation of the enrichment control device 100 is controlled by a temperature and vacuum responsive device 102. The functioning of both of these devices is set forth in the aforenoted Olson application and no further reference need be made to these devices.

An additional lever 128 is pivotally mounted in the metering control device 30 and has one end adapted to engage the top of the metering plunger 82 and the other end articulated to a link 1310. Link 130 has fixed to its other end an armature 132 of a solenoid or servo device 134. The solenoid 134 is connected through a lead wire 136 to the ignition system, as described in Serial No. 608,853, in such a way that when the starting motor is energized solenoid 134 is also energized moving armature and rod 130 upwardly and in turn depressing the metering plunger 82 to insure maximum fuel flow to the cylinders during starting of the engine. When the starting motor is deenergized solenoid 134 is also deenergizcd so that a spring element 138 moves the armature 132 to its lower position moving the lever 128 out of contact with the plunger 82.

Inasmuch as Wall 50 is perforated so as to permit communication between chambers 44 and 48 it is apparent that the pressure above the fuel level in these chambers will be the same. Further, any pressure above the fuel level will act on the upper end of the metering valve sleeve member 82 as Well as on the underside of diaphragm 92 through leakage around the control rod 93.

When the engine is idling under conditions of high ambient temperatures or low atmospheric pressures, as would be the latter case when operating in mountainous areas, vapor pressures build up within chamber 44 and 48 to an extent causing this pressure force to act downwardly on the upper end of metering sleeve 82 and up- Wardly on the diaphragm 92 both of which actions tend to close the spill ports 80 and thereby supply additional fuel to fuel supply conduit 28. The consequence of this added fuel is to over-enrich the idling mixture and so to cause the engine to stall. This situation has been eliminated by providing a conduit 110 which communicates at one end with fuel reservoir 44 and at the other end with the fuel induction passage posteriorly of the throttle valve 14. More specifically end 1120f conduit 110 communicates with the idle bypass system 114. In this way manifold vacuum draws the fuel vapors out of the chambers 44 and 48 preventing the build-up of pressures therewithin.

If full manifold vacuum were admitted to the full reservoir the result would be just the opposite of the problem intended to be solved, i.e., a vacuum would act on the diaphragm 92 and metering sleeve 82 causing the spill ports 80 to be uncovered further which Would lean out the fuel mixture to an extent causing the engine to be starved for fuel and so stall. However, it has been found by providing an orifice 116 in conduit 110 or more particularly in the drilled passage 118 in the induction passage housing, the vacuum force in the conduit may be reduced to a very low value which is sufficient to sweep the vapors out of the chambers 44 and 48. While the size of orifice 116 obviously be varied to suit the particular operating characteristics of an engine, it has been found in the present installation that an orifice of a sufficient size to provide vacuum of approximately .05 inch of water is adequate. This vacuum level is sufficiently low value as not to interfere with the normal metering operation of diaphragm 92.

\Ve claim:

1. A fuel injection system for an internal combustion ."igine comprising an air intake passage, a throttle valve for controlling flow through said passage, a fuel reservoir, conduit means communicating the reservoir With the individual cylinders of the engine, valve means disposed in said reservoir for controlling fuel flow to the conduit means, at least one end of said valve being exposed to the pressure in said reservoir above the fuel level, a pump for supplying fuel under pressure to said valve means, a pressure responsive member connected to said valve, a conduit connecting said member to the intake passage anteriorly of said throttle valve for controlling said valve in response to the quantity of air flowing through said passage, said pressure responsive member being exposed to the pressure in said reservoir above the fuel level, and means for transmitting manifold vacuum to said reservoir to maintain a substantially constant pressure above the fuel level in the reservoir despite changes in atmospheric conditions.

2. A fuel injection system for an internal combustion engine comprising an air intake passage, a throttle valve for controlling flow through said passage, a fuel reservoir, conduit means communicating the reservoir with the individual cylinders of the engine, valve means disposed in said reservoir for controlling fuel flow to the conduit means, at least one end of said valve being exposed to the pressure in said reservoir above the fuel level, a pump for supplying fuel under pressure to said valve means, a pressure responsive member connected to said valve, a conduit connecting said member to the intake passage anterior-1y of said throttle valve for controlling said valve in response to the quantity of air flowing through said passage, said pressure responsive member being exposed to the pressure in said reservoir above the fuel level, a conduit communicating the intake passage posteriorly of the throttle valve with the fuel reservoir, and means for reducing the manifold vacuum in the latter conduit to a value which will not interfere with the normal operation of said valve.

3. A fuel injection system as set forth in claim 2 in which the flow reducing means comprises a fiow restrictor intermediate the manifold vacuum conduit and the intake pass-age. f

References Cited in the file of this patent UNITED STATES PATENTS 1,350,001 Bradbury Aug. 17, 1920 2,394,663 Carlson et a1 Feb. 12, 1946 2,441,301 Waag et May 11, 1948 2,502,679 Stanly Apr. 4, 1950

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