US2883976A

US2883976A - Method of adjusting fuel injector valves

Info

Publication number: US2883976A
Application number: US622624A
Authority: US
Inventors: Stephen G Woodward; Curtis A Hartman
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1956-11-16
Filing date: 1956-11-16
Publication date: 1959-04-28
Anticipated expiration: 1976-04-28
Also published as: FR1196937A; DE1072428B

Description

April 28, i959 s. G. wooDwARD Erm. 2,3%975 METHOD oF ADJUSTING FUEL INJECTOR VALVES Filed Nov. 16, 1956 3 Sheets-Sheet 1 TTRN'Y April 28, 1959 s. G. WOODWARD HAL 2,883,976

METHOD OF ADJUSTING FUEL INJECTOR VALVES Filed Nov. 16, 1956 3 Sheets-Sheet, 2

@n TToRA/EY IN V ILV TORS Apri 28, w59 s. G. WQODWARD ETAL METHOD OF' ADJUSTING FUEL INJECTOR VALVES Filed Nov. 16 1955 mgm.

INVENTORS Unite States METHOD OF ADJUSTING FUEL INJECTOR VALVES Application November 16, 1956, Serial No. 622,624

3 Claims. (Cl. 12S-119) The present invention relates generally to fuel injection systems and more particularly to a method of adjusting the injector valves of said system. US. application Serial No. 567,688 filed February 24, 1956, in the names of Robert W. Sutton et al. assigned to the assignee of the present invention and now abandoned, discloses and claims a fuel injection system having solenoid actuated injector valves to which thc method of adjustment of the present invention is particularly applicable.

vlanulacturing variables introduce variations in the llow characteristics of the disclosed solenoid valve which must be compensated for by adjustment in order to obtain satisfactory distribution in the fuel injection system. Adjustmcnt of the valve by positioning an armature stop member in a predetermined position such as by the number'ot' turns of the stop member in a threaded retainer or by relation to a reference point, has in practice, proved highly unsatisfactory.

lt has been discovered that by applying a source of electrical energy to the solenoid and measuring the current through the solenoid or voltage across the solenoid that an abrupt change in current and voltage occurs at the time the armature or valve engages the stop member. It was further discovered that by adjusting the stop members of a plurality of injectors to obtain the same time duration from the time of application of the source of electrical energy to the time of the abrupt change in cur rent or voltage that for equal energization of the solenoids equal fuel flow through the nozzles was obtained.

lt is accordingly an object of the invention to provide a simple, accurate method for adjusting electrically actuated valves to obtain uniform operation.

lt is a further object of the invention to provide a method for adjusting electrically actuated fuel injector valves which permits the valves to be adjusted in their normally operative installed position.

Other objects and advantages will be readily apparent t rom the following detailed description taken in connection with the appended drawings in which:

Figure l is a schematic view of a fuel injection system;

Figure 2 is a sectional View of an injector valve;

Figure 3 is n graph displaying a characteristic operating curve ol the solenoid valve; and

Figure 4 is a schematic view of the circuitry of the electronic control box shown in Figure 1.

Referring now to thc drawings and more particularly to Figure l, numeral designates a fuel tank, 12 a pump mounted for dcliverying fuel received from the tank through a strainer or lter 14 to a fuel injector valve 16 via conduit 18. Injector 16 is mounted in the induction passage 20 of a multi-cylinder internal combustion engine to inject fuel adjacent the inlet valve 22. The engine is shown fragntentarily and includes a combustion chamber 24 with a piston 26 mounted therein and a spark plug 28 mounted thereon.

Pump l2 is adapted to deliver fuel at a controlled conslant or variable pressure to injector 16. The injector valve 16 is opened for a period of time depending upon 2,883,976 Patented Apr. 23, 1959 a control, to be described, whereby the quantity of fuel injected into the induction passage 20 varies as a function of time duration of valve opening and the pressure of fuel supplied to the injector. Excess fuel supplied to the injector 16 is returned to the fuel tank through conduit 30 and restriction 32.

The control for the injector 16 includes throttle body assembly 3d, electronic control 36 and trigger-distributor 38. In operation, the trigger-distributor 38 triggers or energizes the electronic control 36 periodicalhl as a function of engine speed. Upon energization, the electronic control 36 produces a pulse of electrical energy the width or time duration of which is dependent upon various conditions which effect engine operation. Engine operating conditions are sensed by various elements in the throttle body assembly 34 and are supplied to the electronic control by appropriate conductors. The `output of the electronic control 36 is connected to injector distributor 38 whereby the pulse of electrical energy is connected to the appropriate solenoid in the circuit in accordance with the tiring order of the associated engine. The solenoid in the injector valve 16 remains energized for a period of time dependent upon the width of the electrical pulse.

The throttle body assembly 34 includes a throttle body 40,

induction passages

42 and 44 with throttle valves 46 and 4S respectively mounted therein on a shaft 50. A throttle lever 52 is secured to shaft 50 and is adapted for actuation by a conventional accelerator pedal 54 through a rod S6. A temperature control 58 is mounted on one side of the throttle body and is connected through a link 60 with a fast idle cam 62 which is mounted for engagement with the throttle lever 52 to oppose the closing of the throttle when the control 58 is cold. Also mounted on body 10 is a vacuum responsive element 64 which is adapted to actuate a variable resistor or potentiometer 66. The latter being connected through appropriate lead 68 to a switch 70 mounted on the body 40 for actuation by throttle shaft 50. Switch 70 is connected by lead 72 to the electronic control 36. Ambient temperature responsive element 7d, atmospheric pressure responsive element 76 and engine temperature responsive element 70 are connected by appropriate leads to the electronic control 36. An acceleration control 80 responsive to the pressure in the induction passage and containing a resistor 82 is connected by appropriate leads to the control 36.

Referring now to Figure 4 wherein the circuit of the electronic control is shown schematically'. Numeral 84 designates a triggering switch, 88 a distributor and 90 a plurality of solenoids, one for each of the injector valves 16.

A lead 92 is provided to connect the control 36 through a switch 9-l with a source of energy E. The energy source E may be a battery, magneto or alternator conventionally associated with the engine to which the fuel injection system is connected. Likewise, the switch 94 may be the conventional ignition switch for such an engine.

The triggering device or switch 84 is connected by lead 88 to the control 36 and by lead 100 to ground. Triggering switch 84 is mounted on a shaft 102 for actuation as a function of engine speed; and when actuated produces a series of pulses in lead 104 substantially as shown. Each of these pulses is subsequently transformed into a pair of negative and positive voltage spikes by a condenser 106. A rectifier 108 connected to condenser 106 passes the negative spikes only to the base 110 of a normallyI non-conducting transistor 112 of a monostable multi-vibrator designated generally at 114. The collector 116 of transistor 112 is connected to the base 118 of a normally conducting transistor 120 through lead 122 and condenser C. When the negative voltage spike is applied asesora to base 110, transistor 112 commences to conduct whereby the potential in lead .122 is increased sufficiently to drive transistor 120 into a non-conductive state. The time that transistor 120 remains non-conductive is determined as a function of the voltage decay rate of condenser C which in turn is controlled by the value of certain resistors, to be described, which collect condenser C to ground.

ln the circuit of my invention, condenser C is connected to ground through alternative paths. The first of these paths comprises lead 124, variable resistors or

potentiometers

126, 128, 66 and 82 or shunt 1311, lead 132, lead 63, switch 7G, variable resistors 132 and 1li-i and conductor 136 which is connected to ground or a reference potential. Resistor 126 is varied by element 76 as a function of change of atmospheric pressure, resistor 12S is varied manually, resistor 66 is varied by element 6-'1 as a function of change of induction passage pressure, resistor 82 and shunt 130 are controlled by acceleration device 80. resistor 132 is varied by element 74 as a function of change of atmospheric or ambient temperature and resistor 134 is varied bv element 78 as a function of change in engine temperature. The

resistors

126, 123, 66, 82, 132 and 13-3 are collectively designated as R1.

The second of the paths connecting condenser C to ground comprises lead 12d, variable resistors 126 and 128, lead 72 and variable resistor 138. switch 711,

variable resistors

132 and 134, and lead 140 which is connected to ground or a reference potential. esistor 138 is varied manually. Switch 70 is operatively connected to the engine throttle valve and is arranged to close the second path above described when the throttle is closed to a predetermined

positiont Resistors

1215, 123, 138, 132. 134 are collectively designated R2.

1n the operation of the multi-vibrator 11-'1 the negative voltage spike triggers transistor 112 into conduction whereupon transistor 120 is driven into a non-conductive state. Transistor 1213 remains non-conductive until the voltage on condenser C has decayed to a certain value. When the voltage on condenser C as applied to base 1.18 reaches a predetermined value transistor 12) becomes conductive and transistor 112 is rendered non-conductive. Transistor il?, remains non-conductive until retriggered by a negative voltage spike.

The action of the multi-vibrator produces a pulse in output lead 142 the width of which is controlled as a function of the time constant RIC or RZC depending upon the position of switch 79. The amplitude of the pulse in lead 142 varies from the normaly conducting voltage El to substantially zero. The output of the multi-vibrator 114 is coupled to a power amplifier designated generally at l-i--i hrough lead 142. condenser 148 and lead 150. /t diode 152 clamps lead 150 to lead 92 to insure a substantially constant steady state voltage Ein lead 151) with reference to the voltage in lead 92. A pulse in lead 1&2 produces a pulse in lead 151i of substantially the same width as the pulse in 142. The amplitude of the pulse in 150 varies from tlc reference voltage E to a lower voltage E2.

The puise in lead 150 causes transistor 154 in amplier l-i-i to conduct. The time that transistor -5 conducts is determined by the width ot" the pulse in lead 151) 'which in turn is determined as a function of the time constant RC or REC. The output of transistor 154 is amplified by cascaded transistors 158 and 16u. The output of the amplifier section l-i-'l is connected by lead 162 to a cornmutator ring 16d in distributor 88. A wiper arm 166 mounted on shaft 102 successively connects ring 154 to contact segments 163. The contacts 168 are respectively connected to solenoids 90 in the injector valves 16. The connections between contacts 168 and solcnoids 16 are arranged so that successive engagement of the arm 166 with contacts 1153 cnergizes the solenoids in accordance with the tiring order ofthe engine on which the solenoids are installed.

The injector 16 as best shown ln Figure 2 comprises a body 170 with an atrial conduit 172 passing therethrough. A metering restriction 174i threadedly received in the discharge end of conduit 172 provides a seat for a plastic 0r rubber like valve 176 which is secured to a piston or armature 178 for reciprocation in conduit 172. Piston 178 is constructed of magnetizable material and is formed with a plurality of peripherally disposed axial grooves 180 of such size as to permit the free passage of fuel around the piston. A cylindrical abutment or stop member 182 is threadedly received in conduit 172 upstream of piston 178 and is provided with an axial bore 1&4 and at the lower end is provided with a plurality of slots 186 of such size as to permit the substantially non-rcstricted ow of fuel through member 182. A spring 183 is disposed between stop member 182 and piston 173 to urge them into a normally spaced relation. Solenoid 90 is located in body 179 in a manner to surround at least a portion of the stop member 182 and piston or armature 178. Upon energization of the solenoid 90 by a pulse of electrical energy the piston 173 is moved into engagement with stop member 182 and held there for the time duration of the application of the pulse of electrical energy. Adjustment of the stop member 182 for a given electrical pulse and a given fuel pressure will vary the quantity of fuel discharged by the injector. Bccause of manufacturing tolerances, differences in materials, etc. it is ditlicult or impossible to produce injectors in quantity that will have exactly thc same tiow characteristics for a given electrical pulse and fuel pressure. Because of the variation in the injectors it is difficult or impossible to adjust thc stop members to compensate lor these variations by indexing the stop member a certain number of turns or positioning it in relation to a predetermined reference point. For some time the only method of adjusting the valve was by trial and error which required removing the injector from its operative position, removing the fuel connection, changing the position of the stop member, reconnecting the fuel hose and then measuring the quantity ot` fuel discharged This trial and error method would have to be repeated a number of times for each injector valve.

1n Figure 3 there is shown a graph of the current in the voltage across the solenoid 90 plotted against time. Figure 3 is representative of what might be seen on an oscilloscope connected to a solenoid 9) and triggered by the same pulse of electrical energy applied to the solenoid. As noted in Figure 3 current and voltage increase and decrease respectively smoothly until time T has elapsed at which time an abrupt change occurs. This abrupt change occurs at the time that piston 178 engages stop member 132. By adjusting the stop members 182 in each of the injector valves 16 so as to produce the same valve opening time T from the time of the application of the pulse of electrical energy to the time of abrupt change in current or voltage then for a given pulse of electrical energy and for a given fuel pressure the injectors will discharge substantiaily the same quantity of fuel.

We claim:

1. The method of adjusting a plurality of solenoid actuated fuel injectors having a stop member and an armature so as to provide for equal distribution of fuel to the cylinders of a multi-cylinder internal combustion engine comprising the steps of applying a source of electrical energy to said solenoids, adjusting the stop member of one of said injectors to produce a desired fuel flow, measuring the current tiow in the solenoid of said one injector, measuring the time duration from the application of said source to the occurrence of a marked change in current in the solenoid of said one injector, and adjusting the stop members in the remaining injectors to obtain in the remaining solenoids substantially the same time duration from the application of said source to the occurrence of a marked change in current as the time duration in the solenoid of said one injector.

asesora 2. The method of adjusting a solenoid actuated fuel valve having a stop member and an armature comprising the steps of applying a source of electrical energy to said solenoid, measuring the current ow in the solenoid, measuring the time duration from the application of said source to the occurrence of a marked change in current ow in said solenoid, and adjusting said stop member to provide a predetermined time interval between the application of said source and said marked change in current flow.

'3. The method of adjusting a solenoid actuated fuel valve having a stop member and an armature so as io calibrate said valve to a reference condition comprising the steps of applying a source of electrical energy to said solenoid, measuring the current ow in said solenoid, and adjusting said stop member to obtain a reference time duration from the application of said source o the occurrence of a marked change in current ow in said' solenoid.

Reierencea Ciied in the le of this patent UNITED STATES 'PATENTS 1,268,913 Bair et al June 11, 1918 1,892,917 Walker et al 1an. 3, i933 2,619,116 Ramon Nov. 25, 1952