US3026928A

US3026928A - Fuel delivery system

Info

Publication number: US3026928A
Application number: US678616A
Authority: US
Inventors: Delbert L Phillips; Lavergne L Smith
Original assignee: Telecomputing Corp
Current assignee: Telecomputing Corp
Priority date: 1957-08-16
Filing date: 1957-08-16
Publication date: 1962-03-27
Anticipated expiration: 1979-03-27

Description

March 27, 1952 D. l.. PHILLIPS ETAL 3,026,928

FUEL DELIVERY SYSTEM Filed Aug. 16.71957 4 Sheets-Sheet l ff I II l n l ll L u #xda ngi/afm March 27, 1962 D. L. PHILLIPS ET AL FUEL DELIVERY SYSTEM 4 Sheets-Sheet 2 Filed Aug. 1e, 1957 .WEE WS IIIII D. L. PHILLIPS ET AL 3,026,928

March 27, 1962 FUEL DELIVERY SYSTEM 4 Sheets-Sheet 3 Filed Aug. 16, 1957 mi? 6 I 265 .Ag/53 25H25? /25/ March 27, 1962 D. l.. PHILLIPS ET AL 3,026,928

FUEL DELIVERY SYSTEM Filed Aug. 16, 1957 4 Sheets-Sheet 4 V Ein/({mlu www y Taffy? I y #die M065 Ma a Q (amen/: Q (Irren/f United States Patent O "i ce 3,026,928 FUEL DELIVERY SYSTEM Delbert L. Phillips, Los Angeles, and Lavergne L. Smith, Reseda, Calif., assignors to Telecomputing Corpora-` tion, a corporation of California Filed Aug. 16, 1957, Ser. No. 678,616 20 Claims. (Cl. 158-36.3)

This invention relates to fuel systems wherein fuel is pumped through a fuel line from a fuel source ldirectly to a fuel injection system of an engine or to the carburetor or carburetors of an engine or to the fuel distribution system of a turbine. The present practice of the invention refers particularly to such a fuel system for an internal combustion engine wherein the fuel is kmaintained under pressure for injection directly into the engine, with the periods of injection timed with the engine cycle and with the duration of the periods varied for control of the engine in accord with various condi` tions. Such a fuel system is disclosed in a paper published by the Society of Automotive Engineers, entitled Electrojector Bendix Electronic Fuel Injection System by A. H. Winkler and R. W, Sutton presented at the SAE annual meeting January 14-18, 1957. This published disclosure is hereby incorporated into the present disclosure by reference.

In the above-mentioned Bendix system, the injection of fuel into the plurality of cylinders of the engine is controlled by a corresponding plurality of solenoid injection valves which are operated by timed pulses of electric current. The duration of the pulses of current is not only varied for control of the power output of the engine but is also influenced by a number f automatic means to compensate for various factors under various Operating conditions. p

The fuel is delivered to the engine through a fuel line from a fuel tank and the fuel line is ordinarily of substantial length. In a typical Present day automobile the fuel line may be of a length on the order of l5 to 20 feet. The fuel is `forced into the fuel line by a pump between the fuel source and the engine and this pump functions to maintain the -fuel line under the required pressure for injection of the fuel by the solenoid valves. For example, the required pressure at the solenoid injection valves in the Bendix system is 20 p.s.i.:*;1/2 p.s.i.

In the Bendix system, accurate control of the engine air to fuel ratio by variation of the durationl of the pulses of electric current to the injection valves requires accurate maintenance of substantially constant pressure in the fuel line at the engine. The present invention is directed to this particular problem of maintainingthe fuel pressure constant at the engine end of the fuel line by appropriate control of the relatively remote fuel pump near the inlet end of the fuel line. This problem arises primarily because the pressure drop in the fuel line between the pump and the engine v-aries with the rate of ow in the fuel line, the fuel pressure at the injection valves tending to drop whenever the fuel demand by the engine increases.

In general the invention meets this problem by varying the power applied to the pump in accord with changes in the rate of fuel flow through the fuel line to compensate for the changes in pressure drop in the fuel line. Thus, the pump applies a minimum input pressure to the fuel in the fuel line to maintain a predetermined fuel pressure at the engine under conditions of minimum fuel demand and increases this minimum input pressure with increasing fuel ow to maintain the desired predetermined fuel pressure at the engine.

One practice of the invention includes means to `detect changes in pressure of the fuel at the engine together with means to vary the power applied to the pump in response to the detected pressure changes. In other practices of the invention, the desired control is based on the speed of operation of the pump which, in turn, varies with the head against which the pump operates, which, in turn, varies With the rate of fuel consumption.

With reference to control of the power applied to the pump based on the Aspeed of operation of the-pump, a feature of the invention is the concept of actuating the pump by an electric motor in an arrangement in which the distribution of voltage in the motor circuit, including the voltage drop across the motor, varies with the motor speed and the further concept of varying the power applied to the motor in response to changes in this voltage distribution. Thus, when the motor speeds up with increased fuel flow, the power input to the motor is automatically increased to boost the motor torque in compensation for the increased pressure drop at the higher rate of flow through the fuel line. Preferably, the fuel pump is of the positive displacement type for maximum sensitivity to changes in the fuel demand by the engine.

Another feature of some practices of the invention is the concept of energizing the pump motor in a periodic manner with the periodicity of the motor energization varied in accord with changes in fuel consumption to compensate for changes in pressure drop in the fuel line.

In one such control arrangement a vibratory switch is Yemployed and the vibratory operation of the switch is` varied indirect response to changes in the Ifuel pressure at the engine end of the fuel line. In another control arrangement, means is provided to vary the operation of the vibratory switch in response to changes in the motor speed.

The problem of maintaining substantially constant pressure at the engine end of the fuel line of an automotive vehicle is further complicated by the eifect of inertia on the fuel in the fuel line when the vehicle is `accelerated or decelerated. The mass of fuel in the fuel line resists such acceleration or deceleration with consequent-effect on the fuel pressure at the engine end of the fuel line. At an acceleration loading of 1/2 G, the pressure change at the end of an l8-foot fuel line is in excess of 3 p.s.i.

A further teaching of the invention in this regard is the provision of inertia-sensitive means for creating compensating changes in the power applied to the fuel pump. While such an inertia-sensing means may be a separate control` component, for example, a pendulum, a feature vof the invention is the further concept of employing a vibratory control switch for the pump motor, which switch is oriented for inherent responsiveness to inertia.

The various features and advantages of the different practices of the invention may be further understood by reference to the following detailed description and the accompanying drawings.

In the drawings, which are to be regarded as merely illustrative:

FIGURE l is a diagrammatic view illustrating one practice of the invention that employs a motor-controlling switch that senses the pressure in the fuel line at the engine, thi-s switch being shown in section;

FIGURE 2 is a similar diagram illustrating a second embodiment of the invention wherein the motor is controlled by a vibratory switch that responds to changes in the voltage distribution in the motor circuit;

FIGURE 3 illustrates a third embodiment of the invention in which the current to the motor is controlled by a carbon pile resistance and the carbon pile resistance, in turn, responds to changes in the distribution of the voltage in the motor circuit;

FIGURE 4 is a diagram of a control unit for the motor that is employed in a fourth embodiment of the invention. A vibratory control switch in the motor circuit not only responds to changes in voltage distribution in the motor Patented Mar. 27, 1962 3 circuit but also responds to inertia forces that tend to vary the pressure in theV fuel line at the engine;

FIGURE 5 is a diagrammatic view illustrating another practice of the invention wherein a fine control is a pressure reducing valve near the vend of the fuel system and a course control unit is any one of the electrical control yunits shown in. FIGURES 2, 3 and 4; Y

FIGURE 6 is a diagram representing another practice offthey invention which `also employs a ne control in combination with a course control, the tine control being the pressure reducing valve of FIGURE 5 and the course control being the pressure sensitive switch of FIGURE 1;

FIGURE 6a is a diagramof a modification of the control unit shown in FIGURE 4; v

`FIGURE 7 is a view largely in cross section showing the construction of a relief valve with a bleeder by-pass that may be employed in the various practices of the invention; k

FIGURE 8 is a graph indicating the characteristics of the motor that is employed in the preferred practices of the invention; Y v

FIGURE 9 is a graph illustrating the cyclic operation of la. vibratory motor switch when the fuel demand of the engine is relatively low; and. l

vFIGURE-l() is a similardia'gram indicating the behavior of the vibratory switch when the fuel demand ofv the engine is relatively Ihigh.

:In the `first practice oftheinvention illustrated by FIG- URE l, .the fuel-system. includes: a fuel tank containing aliquid fuel; a pump 22 driven-by a motor 2.4; a fuel passage means y25 from the fuel tank 2,0to the intake of the 7'pump 22; a fuel distribution system or manifold 26 mounted on.anlinternalicombustion engine 28; suitably controlled injection valves 3)` for. the various cylinders of the enginega fuel line 32 for the discharge side of the pump 22' to the manifold 26; .a fuel passage means 34 from .the manifold 26 for return ow'to the fuel-tank 20; and suitable means 35 inthe fuel passage means 34 to control or restrict the return of fuel tothe tank. The meansy 35 to control return flow to the fuel tank 20 may be a bleeder means and/or a pressure relief valve.

Preferably the means `35 for controllingrreturn flow to lthe fuel tank comprises a relief valve with a bleeder by-pass. FIGURE 7 shows by way of examplea relief valve35 that may be used in the fuel passage means 34. The relief valve 35 is of a well known type in which a ball valve'member 36 is confined by a cage 38 for movement relative to a valve seat 40, the valve member being unged towards the valve seat by a suitable spring 42.. The bleeder by-pass consists simply of a small groove 44 in the valve seat 40 for leakage flow at an exceedingly small rate whenthe Yball valve member is seated. v

:In '-a typical practice of the invention, the-desired regulated fuelpressure at the manifold 26 may be, for eX- ample, 2O p'.s.i.y In-such an installation the spring 42 in the relief valve 3S will be selected-to yield at a` somewhat higher pressure, sayy 201/2 p.s.i;, to open automatically whenever the pressure at the manifold 26 surges to that magnitude. The size of the groove 44 for the bleeder by-pass flow may, for example, be equivalent toa bore of a-diametery of .013 inch. The main function of the bleeder by-pass is to purge the fuelV line 32 of vapor and/or incondensable gases 'and an important advantage of employing as groove in a check valve for this purpose is that the bleeder by-pass is flushed every time the check valve opens in response `to a pressure surge. Y

In this' first practice of the invention, vthe motor 24 is controlled by Aa vibratory switch, generally designated 45,-the-cyclic behavior of which responds to the pressure inithe fuel line 352;y at the manifold 26 in a manner-to maintain the pressure substantially constant. For example, wherethe desired pressure level is approximately 20V pfsi.; the vibratory switch 45 will limit the range of conditions.

The vibratory pressure-sensitive switch 45 has a pipefitting body 46 forming aV chamber 4S for ow of fuelV connection -to the motor. circuit. .A movable contact 55` for cooperation with the xed contact S2 is carried .by the end of a tubular member 56. The tubular member 56 interconnects and is carried by a pair of diaphragms 5S and 6i) that form opposite sides of the chamber 48 and these two diaphragms differ in their effective areas to cause the contact 55 to respond to pressure changes in the chamber 48.

IThe diaphragm 58 has a relatively small pressureresponsive area and the diaphragm 6th has a substantially larger pressure-responsive area so that rise in the fluid pressure in the'chamber 48 causes the contact 55 to move away from the rfixed contact 52. The movement ofthe contact 55 in the direction away from the fixedV contact 52 is resisted by a suitable spring 62 that extends into the tubularpmember 56 and is in abutment against the end of a screw 64 for adjustment by the screw. The adjustment screw' 64, which is adapted for connection to the motor circuit, is mounted in the closure member 50 and is releasably retained at adjusted positions by a suitable lock nut 65. The movable contact 55 is electrically connected with the adjustment screw 64 by the tubular member 56 and the spring 62. Assuming that the pressure desired in the fuel line at the manifold 26 is 20 psi., the springl 62-is adjusted to cause the two

contacts

52 and 55 to` close whenever the pressure in the chamber 48v drops below the selected magnitude and to open when the pressure rises above the selected magnitude.

Preferablyv the pump 22 is of a rotary positive displacement type that operates in a substantially pulsation-free manner so that thepressurein the chamber 48 at any given moment is determined by the torque of the motor 24'and the rate-,of fuel consumption by the various injection valves 30. It is further contemplated that the motor 24 when continuously energized will be capable of delivering fuel to the manifold`26 at a rate in excess of the maximum fueldemand by the engine so that cyclic energization of the motor by thek vibratory switchV 45 will be adequate to meet'all engine demands over the operating range.

The motor 24 is energized by a pair of leads 66 andA l 68 from a suitableEMJF. source such as a battery and/ or generator. Lead 66 isconnected to one side of the motor 24 and lead 68 is connected to one side of the vibratory switch 45,` the second side of the vibratory switch being connected to the second side of the motor by a wire 7i) y to complete the motor circuit. lEnergization of the motor circuit is normally tied in with the ignition system of the internalcombustion vengine 28st) that the motor operates wheneverthe ignition circuit is closed. l

SinceY the motor 24 is capable of delivering fuel at a rrate in` excess of the .maximumdemand by the internal combustion engine, energization of the motor under any operating condition results in a prompt rise in pressure in the switch chamber 418 to a magnitude to cause the movable contact 55 to retract from the fixed contact 52. The resultant de-energization of the motor causes a prompt pressure drop in the switch chamber 48 because In the operationof such a vibratory switch, the frey quency and/or the duration of the closed periods of the'y switch varies in accord with changes in the fuel demand and causes corresponding changes in. the average rate of current flow to the motor 24. FIGURES 9 and l0 show, for example, how such a vibratory switch may operate at substantially constant frequency with the duration of the closed periods of the switch varied in response to changes in the fuel demand.

In FIGURE 9 the closed and open periods of the switch are substantially equal to result in an average flow of current at the level indicated by the broken line 72, the motor current `fluctuating between zero and a maximum value indicated by the line 74. When the fuel demand of the engine 28 rises, the vibratory switch stays closed longer on each cycle to restore the fuel pressure to the critical magnitude with the result that the average current iiow to the motor rises to the level of the broken line 75 in FIGURE l0. It is apparent that since the motor has substantial inertia the motor will run continuously as long as any fuel demand exists but will seek some equilibrium speed that will satisfy the engine demand. In FiGURES 9 and 10, it is assumed that the frequency of operation of the vibratory switch is constant, but there will probably be some variation in frequency in the operation of the switch in FIGURE 1 under maximum and minimum operating conditions.

The second embodiment of the invention illustrated by FIGURE 2 employs a fuel passage arrangement similar to the arrangement shown in FIGURE l, as indicated by the use of corresponding numerals to indicate corressponding parts. In this instance it is contemplated that a motor 76 will be used which is a D.C. two-pole permanent magnet type motor. The motor may be of any other type having similar operating characteristics, for example, a shunt wound motor. The desired characteristics of the motor are indicated in FIGURE 8 -where it may be seen that Vwith a constant output torque for the motor the applied armature current is also constant while the applied voltage to the motor is increased with the motor speed.

Since the motor 76 is directly connected to the positive displacement rotary pump 22, the pressure maintained in the fuel line 32 immediately adjacent the discharge side of the pump is determined by the motor torque and, as indicated in FIGURE 8, the torque tends to be constant. With the torque at a magnitude to provide the desired pressure, say 20 p.s.i., at the manifold 26 at low fuel demands by the engine, any increase in the rate of fuel consumption results in corresponding increase in the motor speed without increase in the motor torque. Thus the motor inherently tends to maintain a given pressure at the pump end of the fuel *line 32 at all rates of fuel demand by the engine. The pressure drop in the fuel line 32 varies with changes in the rate of flow, however, so that the pressure at the manifold 26 changes accordingly unless some provision is made for compensating changes in the motor torque. Since the pressure drop varies with the square of the velocity of flow, the maintenance of a constant motor torque will permit the pressure at the manifold 4to drop drastically at peak fuel demands. The present embodiment of the invention provides an automatic control unit represented by the rectangle 80 to compensate for this pressure drop by correspondingly increasing the torque of the motor in accord lwith increases in the rate of fuel consumption by the engine.

The functioning of lthe control unit Si) depends upon the fact that if the motor 76 is energized by a constant voltage source with resistance in series" with the motor, the distribution of lthe voltage in the motor circuit, including the voltage drop across the motor, will vary with the speed of operation of the motor. Thus if the speed of the motor rises in response to an increase in the rate of fuel consumption by the engine, the voltage drop across the motor will rise in the manner indicated in FIGURE 8 and the voltage drop in the rest of the motor circuit will be reduced accordingly. p

The purpose of the control unit S is to increase the torque to the motor in response to the progressive change in voltage distribution that occurs with progressive ncrease in the rate of operation of the motor. It is apparent that such a control unit may either respond directly to voltage changes across the motor or may respond directly to the inverse changes in voltage across resistance in the motor circuit. In this particular instance the control unit 8i) responds directly to changes in the voltage drop across the motor 76.

The portion of the motor circuit encompassed by the control unit 8f) includes a vibratory switch of the buzzer type comprising a flexible magnetically responsive switch arm S2. The switch arm 8'2 carries a contact 84 for cooperation with a fixed contact S5, these two contacts being in series with the motor 76 and being shunted by a resistor 86. The switch arm 82 is connected to one lead 88 from a constant voltage source for energization of the movable contact 84 and the fixed contact 85 is connected to one side of the motor by a wire 90, the second side of the motor being connected to a second lead 92 from the voltage source through an electromagnet coil as will be explained later. It is apparent that when the vibratory motor switch is c-losed the motor is connected directly across the

leads

88 and 92 for current flow to the motor at a maximum rate and that the opening of the vibratory switch reduces the current flow to the motor.

to some minimum value determined by the switch-shunting resistor 86.

It is contemplated that the flexible switch arm 82 will vibrate at a relatively rapid rate with an essentially constant frequency and that lthe range of vibration of the switch will shift in response to the changes in voltage across the motor 76. To cause the required continual vibration of the switch arm 82, a contact 94 is mounted ony the switch arm by a leaf spring 95 for cooperation with a fixed contact 96. The switch arm 82 is resiliently biased to bring the movable contact 94 against the fixed contact 9'6 and an electromagnet 93 is arranged to attract the switch arm in the opposite direction to move the contact,

94 away from the fixed contact 96. One side of theA electromagnet 9d is connected to the `fixed contact 96 and thel lother side is connected by a wire to the second lead 92. It is apparent that the vibratory switch will operate in the manner of a buzzer since the electromagnet' 98 will repeatedly attract the flexible switch arm to its openl position with respect to current flow through the two contacts 94 and 96. The flexible switch arm 82 has a shading coil 99 mounted thereon which has the function of maintaining the amplitude of the flexible arm essentially constant even though the voltage may va-ry and of causing the arm to vibrate at a non-resonant frequency. The shading coil 99 may be either a wire coil whose terminals are joined to form a closed loop or it may be a ring of conducting metal. Alternatively, the shading coil may be located on the core of the electromagnet 98. Also, the flexible switch arm 82 may carry a small weight 102 which may be varied for adjustment of the frequency of vibration of the switch arm.

Control with respect to the average rate of current flow to the motor is exercised by a second regulating electromagnet having a fixed core 104 and two

separate coils

105 and 106. This regulating electromagnet is positioned to attract the flexible switch arm 82 in the direction to carry the movable contact 84 away from the fixed contact 85 but the magnetic attraction is merely strong enough to influence the behavior of the flexible switch arm without at any time causing the movable contact 84 to be held away from the fixed contact 85. Thus the effect of the magnetic field exerted by the regulating electromagnet is to decrease the duration of the closed periods of the two contacts 84 and 85 thereby to decrease the average current flow which determines the motor torque. strength of the regulating magnetic field is at maximum for minimum rates of fuel demand by the engine and is automatically progressively reduced with progressiveincrease in the rate of fuel demand.

The

the regulating electromagnet may be termed a voltage-v sensing coil since it is connectedacross the motor 76 to respond directly to changes in the voltage across thel motor. One side of the voltage-sensing` coil 106 is connected to the previously mentioned wire 93 and the other side is connected by a wire S to an adjustable resistor 110, the adjustable resistor in turn being connected to the ywire 90` ou the second side of the motor.

As the speed of operation ofthe motor 76 increases in response to increaseV in the fuel demand by the engine,l the voltage across the motor increases with consequent increase Yin current flow through the voltage-sensing coil 106. The polarity yof the voltage-sensing coil 186 is rejver'sed with respect to the polarity of the current-sensing:

coil 105 so that' the magnetic iield of the voltage-sensing coil bucks or opposes the magnetic field of the current sensing coil. Consequently the increase in the current flow through the voltage-sensing coil reduces the strength. of the regulating magnetic eld that is coupled with the flexible switch arm 82. With weakening of the regulating magnetic field the magnetic bias of the switch arm away from the fixed contact `85 is reduced and the duration of the closed-periods ofthe two contacts 84 and 85 is increased for resulting increase in the average rate of cur rent flow to the motor 76. Thus the current flow to the motor. is increased to increase the torque of the motor automatically as required tofcompensate for pressureV drop in the 'fuel line 32 between the pump 22 and the engine manifold 26.

Thefuel system shown in FIGURE 3 is identical to the fuel system shownin FIGURE 2 except for a control unit 1.12 that is` substituted for the control unit 80.

The controlunit 112includes `a variable resistor in the form of a carbon pile 114 and also includes regulating electromagnetic means in the form of a regulating solenoid having a movable core or armature 115 and two coils 11'6 and .118. A suitable spring 120 under adjustable compressionbya screw 122 presses against the armature 11'5 in a' direction to increase the pressure on the carbon pile 114. Y

One side of the motor 76 is connected directly to one lead12`4 from a constant voltage source. One end of the coil 116 is connected to the second lead 1215 and the second side of the coil116 is connected yby a wire 126 to one side of the carbon pile 114. The same side of the coil 116 is ralso'cormected to one side of the coil 118 by a wire 128 'and two= resistors 130 and 132 in series, the resistor 132 being a trimming resistor. A fixed resistor 134 and a trimming resistor 135 shunt the coil 116 in parallel, the two resistors interconnecting lead 125 and wire 128. The second side of the coil 118 and the second side ofthe 'carbonfpile 114 are connected tothe second sideI of the motor 76.

It'isapparentthat the coil 116 is in series with the carbon pile 114'and the motor 76 and therefore functions as a current-sensing coil. The polarity of the coil 116 is such. that the magnetic lield created thereby acts on the movable armature 115 in the same direction as the spring 120 to exert pressure on the carbon pile. Since the electrical resistance ofthe carbonV pile variesv inversely with this pressure the tendency is for the spring 120 and the m'agneticeld of the current-sensing coil 116 to increase the flow of current to the motor. C-oil 118, which is a voltage-sensing coil, is in seriesewith the two resistors 1.30 and 132 andf shuntsthe carbon pile 1114.

When the voltage across-the motor 76 rises in response Yto increased Vfuel consumption by-thefengine, the voltage in the rest'of' the motor circuitdrops accordingly and the current flow through coil. 11S drops correspondingly.

8. The coil 118 is of opposite polarti'y to the coil 116 to buclr or oppose the magnetic iield of the coil 116 and therefore reduction of current ow through the coil 118 caused by reduced voltage across the coil with increasing motor speed results in increased pressure against the carbon pile 114 to step up the current ow to the motor. Since the carbon pile 114 is in parallel with the voltage-Sensing coil 11S, the resuling reduction in resistance by the `carbon pile results in diversion of current flow from the voltage-sensing coil 118 to the carbon pile. This diversion of current further weakens the magnetic iield to amplify the current boosting effect. Thus, whenever the motor speeds up in response to increased fuel demand, the control unit 112 correspondingly boosts the motor torque to compensate for the increased pressure drop in the fuel line.

FIGURE 4 indicates the construction of a control unit 140 that may -be substituted for either the control unit 112 of FIGURE' 3 or the control unit 80 of FIGURE 2. Thecontrol unit .140 includes a vibratory switch comprising a resilient switch arm 142 carrying a contact 144 forV cooperation with a contact 145. rlhe switch arm 142 is operated in the manner of a buzzer and for this purpose carries a contact 146 on a leaf spring 1.43l to cooperate with a iixed contact 150, the switch arm being resiliently biased tobring the contact 146 against thecontact 150. An electromagnet 152 for attracting the switch arm 142 away from the fixed contact 150 is connected at oneend to one lead 154 from the constant voltage source and is connected at the other end to the xedvcontact 150. The circuit for the electromaget 152 is completed by a wire 155 from the switch arm 142 to the second lead 156 from the constant voltage source. The switch arm 142 is provided with a lweight 15S for adjusting its frequency of oscillation and preferably has a shading coil 159 for the purpose of maintaining an essentiallyrconstant amplitude of oscillation at a non-resonant frequency. An alternative location yfor the shading coil 159 is on the end of the 'core of the electromagnet 152 adjacent to the switch arm -14l2.

The control unit accomplishes its purpose byV shifting the contact y relative to the range of oscillation of the switch arm 142 to vary the, proportion of the oscillating movement of the switch arm at which the contact i145 abuts the contact 144. Moving the contact 145 up- Iward further into the range of oscillation of the switch arm `142 increases the duration of the periods during which the

contacts

144 and 145 are closed and thus increases the average current flow through the motor 76.

One side of the motor 76 is connected to the lead 154. The other side of the motor isconnected bya wire 160 to a resistor 162 and this resistor is connected in turn to a wire 163 and a resistor 164. The'wire 163 is connected to an angular lever 165 on which they contact l145 is Lrrnounted. Thus, the motor circuit is completed by wire 163, angular lever 4165, `contact 145, contact l144, switch arm 142 and wire 155 from the switch arrnto the lead 156. When the contacts'144 and 145 are open, reduced current is supplied to the motorv through lthe'shunting resistor 164.

The angular lever 165 is mounted on a iixed pivot 166 and is provided with a suitable tension spring 168 which tends to rock the lever in a direction tornove the contact 145 upward into the range of oscillation of the switch arm 142. One end of the tension spring 168 is anchored to a xed stud 170 and the other end is attachedk to the angular lever 165 lby an eye screw 172 which extends through a smooth bore in the angular lever and is adjustably secured therein by a pair of lock nuts 174.

A regulating electromagnet having a lixed core -is positioned to attract the lever :165 in opposition to the tension ofthe spring 168 thereby to cause the contact 145 to take an equilibrium position. The magnetic eld of this electromagnet is weakened in response to Vvoltage changes in the circuit to prolong the closed periods of the

contacts

144 and 145 to increase the torque of the motor 76 automatically whenever the fuel demand by the engine increases. For this purpose the electromagnet has a current-sensing coil 176 and a voltage-sensing coil 178, both coils being of the same polarity whereby their magnetic fields are additive in attracting the angular lever 165 in opposition to the tension spring 168.

One end of the current-sensing coil 176 is connected by a wire 180 with one end of the resistor 162 and the other end of the coil is connected by a wire 182 to the second end of the resistor. Thus substantially the full current to the motor 76 passes through the current-sensing coil 176 to make the strength of its magnetic field substantially constant.

One end of the voltage-sensing coil 178 is connected yto the wire 182 and the other end is connected by a wire 184 to the lead e156. Since the voltage-sensing coil 178 is in parallel with

resistors

162 and 164, its voltage drop and consequently the strength of its magnetic field varies withthe voltage drop across the two resistors.

I When the motor 76 speeds up, the consequent increase in the voltage drop across the motor causes corresponding decrease in the voltage drop across the two

resistors

162 and 164 with consequent weakening of the magnetic field of the voltage-sensing coil 178. The weakening of this magnetic field permits the tension spring 168 to shift the contact 145 further into the range of oscillation of the vibratory switch arm 142 to boost the average current to the motor and thereby increase the motor torque to compensate for the increase pressure drop in the fuel line.

As heretofore pointed out, when a fuel system of the present type is employed on an automotive vehicle with the fuel line extending generally longitudinally of the vehicle, the desired steady pressure in the fuel line at the engine may -be defeated by the inertia of the fuel in the fuel line when the vehicle is accelerated or decelerated. One method of compensating for the inertia of the fuel in the fuel line is to orient the weighted vibratory switch arm 82 in FIGURE 2 so that the vibratory movement of the switch arm will be influenced by acceleration and deceleration of the vehicle, the direction of forward travel of the vehicle being indicated by the arrow F. Thus if the fuel is pumped forward through the fuel line 32 the vibratory switch arm 82 may be positioned forward of the fixed contact 85 whereby the inertia of the switch arm will tend to bias the switch arm towards the fixed contact 85 for momentary increase in the current to the motor to com-pensate for the inertia of the fuel in the fuel line. The same purpose may be accomplished in the use of the control unit 112 of FIGURE 3 where the direction of forward travel of the vehicle is indicated by the arrow F. The movable armature is positioned to extend forward from the carbon pile y114 whereby the inertia of the movable armature will increase the pressure on the carbon pile when the automotive vehicle is accelerated and vice versa.

FIGURE 4 shows how the control unit 148 may be provided -with a pendulum 185 to compensate for the effect of inertia on the .fuel in a forwardly extending fuel line. The arrow F in FIGURE 4 indicates the direction of forward travel of the vehicle and it is apparent that when the vehicle is accelerated or decelerated in its forward travel the inertia of the pendulum 185 will cause the pendulum to swing about its fixed pivot 188. The pendulum 185 is connected to the angular lever 165 in a yielding manner by a suitable push-pull spring 198, the spring acting in compression to resist forward movement of the pendulum relative to the angular lever and acting in tension to resist rearward movement of the pendulum. It is apparent that when the automotive vehicle is accelerated, for example, the rearward swing of the pendulum 185 will exert pull on the spring 19t) -to cause the contact 145 to be moved further into the range of oscillation of the switch arm 142 thereby to increase the current iiow to the motor 10 in compensation for the eect of inertia on the fuel in the fuel line.

FIGURE 5 shows a fuel system incorporating the same general arrangement as heretofore described, corresponding parts being indicated by corresponding numbers. In this instance control of the fuel line pressure is carried out in two stages. What may be termed a tine control is employed in the final stage near the fuel distribution manifold 26 and what may be termed a course control is employed for the iirst stage at the pump end of the fuel line. The ne control comprises a pressure-reducing valve generally designated 192 and the course control is a control unit 194 for the motor 76. The control unit 194 may be the control unit of the system shown in FIGURE 2 or the control unit 112 of the system shown in FIGURE 3 or the control unit 140 shown in FIGURE 4.

The pressure-reducing valve 192 has an inlet port 195, an outlet port 196 and a valve member 198 to seat at the inletl port, the valve member being carried by a tubular stem 200 through which fluid iiows from the inlet port to the outlet port. The upper end of the tubular stern 200 is slidingly confined by a cylindrical guide 202 and the lower end of the stem is slidingly guided lby a surrounding cylindrical portion 284 of the valve body.

The tubular stem 280 extends through and is attached to a pair of spaced

diaphragms

205 and 206 which divide the interior of the pressure-reducing valve into an upstream chamber 288 at the inlet port 195, a downstream chamber 210 and an intermediate diaphragm chamber 212. The upstream chamber 288 is in continuous communication with the interior of the tubular valve stem 200 by virtue of a plurality of elongated apertures 214 in the valve stem upstream from the diaphragm 205 and in like manner the downstream chamber 210 communicates with the interior of the tubular valve stem through a plurality of apertures 215 in the valve stern positioned downstream from the diaphragm 206. The intermediate diaphragm chamber 212 has` a small vent passage 216 to a pressure reference which, in this example, is the atmosphere. The pressure reference may be any desirable source for such pressures as absolute pressure, inlet manifold pressure et cetera.

The tubular valve stem 200 together with the diaphragm 206 presents a relatively large area to the uid in the downstream chamber 210 and the valve stem together with the diaphragm 205 presents a substantially smaller area to the fluid in the upstream chamber 288. With the pressure equalized between the upstream chamber 288 and the downstream chamber 210 the differential pressure on the tubular valve stem created by the

chambers

208, 210 and 212 will urge the valve stem towards the inlet port to close the valve member 198 against its seat.

This differential pressure is opposed by a coil spring 218 that seats on an annular shoulder 220. The spring presses upward against the ange 222 of a flared skirt member 224 that is anchored to the tubular valve stem 200 by a nut 225. The purpose of the spring 218 is to determine and ycontrol the final fuel pressure at the enrd of a fuel line in the region of the distribution manifold 26. The valve member 198 under control of the two diaphragms will open and close` automatically to seek an Vvintermediate open position that will maintain a given equilibrium pressure in the two chambers 208 and 210, the magnitude of the given pressure being determined by the spring 218. This equilibrium pressure is the pressure desired at the distributionv manifold 26 and in this instance is 20 p.s.i. The described pressure-reducing valve 192 will act automatically to prevent a departure of-more than 1/2 p.s.i from this desired pressure.

r)The course control afforded by the control unit 194 cooperates with the motor 76 to maintain a somewhat higher pressure at the upstream pump end of the fuel line 32, say a pressure `of 25 p.s.i. so that the pressure at the inlet port 195 of the pressure-reducing valve is always at least slightly more than the desired ultimate pressure otZ p.s.i. When the fuel demand -by ythe engine increasesVV and the motor and pump speed up to meet this increase,

Y the'course control unit 194 automatically increases the current flow tothe motor to raise the motor torque in compensation for the increased pressure drop in the fuelV line; 32 between the pump 22 and theA pressure-reducing valve 292. Thus the course control unit 194 tends to maintain aconstant pressure at lthe inlet port 195 of the v isl used as the tine control for the desired ultimate pressure of p.s.i. and the pressure-sensitive vibratory switch 45 functions asacourse upstream control to maintain a pressure on the upstream side of the pressurereducing valve that is at least slightly greater than the selected pressure of 20 p.s.i. When an increase in the fuelgdemand bythe engine tends to cause reduction of pressure at the inlet ofthe pressure-reducing valve in consequence ofthe pressure drop between the pump 22 and the pressure-reducing valve, the vibratory switch 45 automatically `functions in the manner heretofore described toincrease the average current to the motor for raising the motor torque thereby to raise the pressure in thefuel line at the pump to compensate for the increased pressure dropinthe fuel line.

FIGURE 6a is a diagram of a control unit for the motor similar yto that of FIGURE 4 which is employed in another embodiment of the invention. A vibratory control switchy in the motor circuit is responsive to changes inthe .voltage distribution in the motor `circuit and toinertia forces that tend to vary the lpressure in the` filet-line at theengine.y

FEGURE 6a indicates the construction of a control i unit 250 which may be substituted for the control unit 14th ofy FIGURE 4, or the control .unit 112 of FIGURE 3, or the controlunit 80 of FIGURE 2. The control unit 250 includes a vibratory switch comprising a resilient ltromagnet261 for attracting the .switch arm 254 Vaway from` [the hxedcontact,2.60 is .connected` at one end to one lead 253,y from the constant voltage source and is conf nected at the .otherzend tothe. fixed contact 260. The circuit for the electromagnet 261 is completed by a wire 262 from the switch arm 254 tothe second lead 252 fromv the constant voltage source. The switch arm 254 isprovidedA with a weight-263 for adjusting its frequency of oscillationand a shading coilV 259 for the purpose of maintaining an essentially constant amplitude of oscillation at a'nonresonant frequency. The shading coil 259 is preferably mounted on the switchy arm 254 as shown but may bevmounted at or near the end of the core of the electromagnet 261 adjacent the switch arm 254.

The control unit 250 accomplishes its purpose by shifting the contact 256 relative to the rrange of oscillation of the switch armA 254 to vary the proportion of the oscillating movementV of the switch arm during which the Contact 256 abuts the contact 255. Moving the contact 256 further upward into the range of oscillation of the switch arm 254 increases the duration of the periods during. which the contactsu255 and^256 areV closed ,and

if?. thus increases the average current flow through the motor 76.

One side ofthe motor 76 is connected to the lead 253. The other side of the motor is connected by Varwire 264 to a current sensing coil 265 of a multiple coil regulating electromagnet and this currentsensing coil is connected in turn to an'angular lever 266 on which the contact256 is mounted. Thus the motor circuit is completed by coil 265, angular lever 266, contact 256, contact 255', switch arm 254, and wire 262 from the switch` arm to the lead 252. When the contacts 255 and 256 are open, reduced current is supplied tothe motor through the shunting resistor 267.

The angular lever 266 is mounted on a fixed pivoty 270 and is provided with a suitable tension springV 271 which tends to rock the lever in a direction to` move the Contact 256 upward into the range of oscillation of the switch arm 254. One end of the tension spring 271 is anchored to a fixed support, and the other end is attachedVV to the angular lever 266 by an eye screw 273 which ex-` tends through a smooth bore in the angular lever and isl adjustably secured therein by a pair of lock nuts 274.r

The multiple coil regulating electromagnet hasa iixed core 275 and is positioned to attract the lever 2 66 in opposition to the tension. of the spring 271 thereby to cause the contact 256 to take an equilibrium position. ltv is contemplated that the magnetic iield of `this regulating electromagnet Vwill be weakened in lresponse to` voltage changes in the circuitto prolong the closed periods 'of the contactsV 255 and 256 thereby to increase the torque and speed of the-motor 76 automatically wheneverthe fuel demand by the engine increases. Fory this purpose the regulating electromagnet has the previously mentioned current-sensing coil 265, a`voltage-sensing coil.

276, and preferably a shading coil 277. The sensing coils 265 and 276 are of the same polarity, whereby their magnetic tields are additive in attracting the angularlever 266 in opposition to the tension spring 271.`

The current sensingl coil 265 is connected inseries with the contacts i255 and 256 and, therefore, jhasfa ypt'llsating current therein..To dampen the pulsing effect of thecurr'ent sensing coil 265 and allow the'lever 266 to ,maintainV an equilibrium position, the shading coil 277 is .mounted at or near the tip of the fixed core 275. .The induced currentin the shading coil 277 resists and slows thepulsing effect of the currentsensing coil .265 on the magnetic -force inthe core 275 and thereby tends to maintain ,theV magnetic force of the core at a constant level, so that the lever 266 will maintain an equilibrium position rather than continuously moving or hunting Although the shading coil damps the pulsing effect of the current coil 265, it -does not materially alter the action ofthe electromagnetin shifting the lever 266 in response to a change in the state ofthe fuelV system, such as an increase or decrease in engine demand level. Although it is preferable to utilize the shading coil 277 -in this form of the invention, it may be omitted under certain conditions.`

The voltage-sensing coil 276 is connected in parallel with the resistor 267 and, therefore, its voltage drop, and consequently the strength of its magnetic field, varies with the voltage drop across the resistor. When the motor 76 speeds up, the consequent increase 1n the voltage drop across the motor causes corresponding decrease in the voltage drop across the resistor 267 with consequent weakening of the magnetic iield of the voltage-sensing coil 276. The weakening of this'magnetic iield permits the tension spring 271 to shift thecontact 256 further into the vrange of oscillation of the vibratory switch arm 254 to *boost the average current to the motor and thereby increase the motor torque to compensate for the increased pressure drop in the fuel line.

lAs previously discussed, in an automotive vehicular application, the desired steady fuel pressure in the distribution system may be upset during acceleration and deceleration by the inertia of the `fuelin the fuelline. The

13 control unit 250 is provided with a pendulum 280 to compensate for the inertia effect on the fuel in the fuel line. The arrow F indicates the direction of forward travel of the vehicle, and it is apparent that, when the vehicle is accelerated or decelerated in its forward travel,`the inertia of the pendulum 280 will cause the pendulum to swing about its iixed pivot 282. The pendulum 280 is connected ,to the angular lever 266 in a yielding manner by a suitable push-pull spring 285, the vspring acting in compression to resist fonward movement of the pendulum relative to the angular lever and acting in tension to resist rearward movement of the pendulum. It is apparent that when the automotive vehicle is accelerated, for example, the rearward swing of the pendulum 280 will exert pull on the spring 285 to cause the contact 2561 to be moved further into the range of oscillation of the switch arm 254 thereby to increase the current ilow to the motor in compensation for the effect of inertia on the fuel in the fuel line.

Our description in specific detail of selected practices of the invention will suggest various changes, substitutions and other departures from our disclosure within the spirit and scope of the appended claims.

We claim:

1. In a fuel system wherein'fuel is forced through a fuel line from a fuel source to an engine or the like, means to maintain pressure in the fuel line at the engine, comprising: a pump to force fuel through said fuel line, said pump being of the type in which increase in pump speed increases the rate of liuid llow; a motor to operate said pump; a circuit to energize said motor to maintain said line under pressure whereby the speed of operation of the motor varies with the rate of fuel consumption byy said engine; and means directly responsive to electrical energy changes in said 1circuit to vary said circuit for increasing the torque of the motor when the motor speed increases thereby to compensate for pressure drop in the vfuel line. l

2. A combination as set forth in claim l in which said circuit includes resistance whereby the distribution of the voltage in the circuit including the voltage drop across the motor |varies with the speed of operation of the motor; and in which said means to increase the torque of the motor when the motor speed increases is directly responsive to changes in the distribution of the voltage in the circuit.

3. A combination as set forth in claim 1 in which said engine or theY like is carried by an automotive vehicle with the fuel line extending generally longitudinally of the vehicle; and in which said responsive means is also responsive to inertia to compensate for the inertia of the fuel in said fuel line when said vehicle is accelerated and decelerated.

4. A combination as set forth in claim 3 which includes pendulum means operatively connected with said responsive means to sense acceleration and deceleration of the vehicle.

5. A combination as set forth in claim 1 which includes a switch controlling at least a portion of the current in said circuit whereby closing the switch increases the motor current and opening the switch decreases the motor current; which further includes means to open and close said switch in a vibratory manner whereby the average current delivered to the motor depends on the frequency and duration of the closed periods of the svn'tch; and in which said means that is directly responsive to electrical energy changes in the circuit varies the vibratory operation of the switch.

6. A combination as set forth in claim 5 in which said circuit includes resistance whereby the distribution of the voltage in the circuit including the voltage drop across thekmotor varies with the speed of operation of the motor; and in which said responsive means responds to changes in said distribution of the voltage drop to increase the average current through the motor when the speed of operation of the motor increases.

7. vA combination as set forth in claim 5 in which said circuit includes resistance in series with the motor wherebythe voltage drop across said resistance is reduced by increase in the motor speed; and in which said responsive means varies the vibratory operation of said switch to increase the average current through the motor in response to reduction in the Voltage drop across at least a portion of said resistance.k

8. A combination as set forth in claim 5 in whichsaid switch is responsive to magnetism; and in which said responsive means comprises a variable electro-magnet magnetically coupled withv said switch, said electromagnet being responsive to changes in current iiow in said circuit with changes in the speed of operation of said motor.

9. A combination as set forth in claim 5 in which said vibratory switch is oriented to respond to inertia forces generally longitudinally of the vehicle.

10. A combination as set forth in claim 5l which includes: a resistance in said circuit whereby distribution of the voltage in the circuit including the voltage drop across the motor varies with the speed of operation of the motor; means to open and close said switch in a vibratory manner whereby the average current delivered to the motor depends on the frequency and duration of the closed periods of the switch; and a variable electro-magnet coupled with said switch to vary the vibratory operation of the switch thereby to vary the average current delivered to the motor, said electromagnet having two energizing coils, one of said coils being responsive to current flow in said circuit, the .other of said coils being responsive to changes in the voltage distribution in the circuit to increase the average current through the motor when the motor speed increases and vice versa.

l l. A combination as set forth in claim l0 in which said two coils are bucking coils and in which said voltage responsive coil responds directly to changes in the voltage drop across the motor. y

12. A combination as set forth in claim' l0 in which said voltage-responsive coil is of the same 'polarity as the current-responsive coil, thel magnetic elds of both coils biasing the vibrating switch towards its open position; and in which said voltage-responsive coil responds to the voltage drop across'at least a portion of said resistance whereby the magnetic field of the Voltage-responsive coil is reduced in response to increase in the motor speed thereby to reduce the magnetic biasing of said switch towards its closed position for increasing the average current to the motor.

13. A combination `as set forth in claim 5 in which said circuit includes resistance whereby the distribution o-f the voltage in the circuit including the voltage drop across the motor varies with the speed of operation of the motor; in which said switch includes a switch member, a first switch Contact carried by the switch member, and a second switch contact adjacent the switch member to we operate with said iirst contact to open at least a portion of the circuit for at least lowering the current ow through the motor in a periodic manner with the ratio of the duration of the closed contact periods relative to the duration of the open contact periods determined by the position of said second contact relative to the range of vibratory reciprocation of the switch member; and which includes an electro-magnet to change the position of said second switch contact relative to said range in response to changes in the voltage distributionin said circuit to increase the average current to the motor when the motor speed increases and vice versa.

14. A combination as set forth in claim 13 in which said engine is carried by an automotive vehicle with said fuel line extending generally longitudinally of the vehicle; and which includes inertia-responsive means to shift said sec ond switch contact to compensate for the effect of inertia on the fuel in said fuel line when said vehicle is accelerated and decelerated.

15. A combination as set forth in claim 14 in which i said. inertia-responsive means vcomprises a pendulurngand which includes spring means to resist attraction of said second switch contact byv said electromagnet. Y l

16. In afuel system wherein fuel is forced through a fuel line fromv a fuel source to an engine or the like, means to -maintain pressure in the 'fuel line at the engine comprising: a pump to force fuel through saidfuel line, said pump being of the type in which increase in pump speed increases the rate of fluid flow; a motor to operate said pump; a circuit to energize said motor with the voltage across the motor varying with the speed of the motor; and means directly respon-sive to increase in the voltage across the motor to increase the torque of the motor to cornpensate for changes in pressure'drop in the fuel line with changes in the velocity of ilowfthrough the fuel line.

17. In a fuel system for an engine or the like wherein iiuidefuel is maintained under pressure in a fuel line for release to the engine, means to introduce fluid fuel from a supply source into the fuel line at a point spaced from the engine with automatic compensation for changes in pressure drop'between' said point and the engine at different rates of fuel demand bythe engine, said means comprising: a pump togforce the fuel from said source into the fuel line, said pump being of the type in which increase in pump speed increases the rate of fiiuid owg'an electric motor to drive said pump whereby the speed of the motor increases with dropping pressure onV the discharge side 0f the pump; a 'circuit to energize said motor including resistance inv series 'withfthe motiorwhereby the distribution of the voltage in theV circuit including the voltage drop across the motor varies with the speed of operationof the motor; a variable resistor in saidncir'cuit to vary the current flow therethrough thereby vto vary thetorque of the motor; and electromagnetic means to control said resistor, said electromagnetic means being responsive to the changes of said distribution of voltage toboost' the current flow to the` motor when the motor speed increases and vice versa. Y l

"18. A combination as set forth in claim 17 in which said variable resistor is a carbon pile; and in which said electromagnet varies the pressure on said carbonl pile.

19. A combination as set forth in claim 18 in which said electromagnet has a first coil responsive to c urrent ow through said rcircuit and a second bucking coil responsive: to the voltage drop across at least a portion of said resistance, the. magnetic field of said second coil tending to decrease the pressure on said carbon pile, said second coil being in parallel With said carbon pile.

20.V In a fuel system for an engine or the like wherein fluid fuel is maintained under pressure in a'fuel line for release to the engine, means to introduce uid fuel from a supply course into the fuel line at a point spaced from the engine with automatic compensa-tion for changes in pressure drop between said point and the engine at different rates of fuel demand by the engine, said means comprising: a pump to force the fuel from said source into the fuel line, said pump being of the type in which increase in pump speed increases the rate of fluid flow; a motor operatively connected to said pump rwhereby the speed of the motor increases with dropping pressure on the discharge side of the pump, said motor having an output torque to maintain the pressure in the fuel line above the pressure required at said engine; a circuit to energize said motor, said circuit including a resistance in series with said motor whereby the distribution of the voltage in the circuit including the voltage drop across the motor varies with the speed of4 operation of the motor; a pressure-reducing valve in the fuel line near `the engine to reduce said pressure in the fuel line -to the desired pressure; and means directly responsive to change in thezdistribution of the voltage in y.said circuit to increase the motor torque to compensate for increase in pressure drop between the motor and the pressure-reducing valve when the speed of the motor increases.

References Cited in the le of this patent UNITED STATES PATENTS 1,534,829 Behnke Apr. 21, 1925 1,933,379 Mock Oct. 31, 1933 2,215,756 Heinrich et al. Sept. 24, 1940 2,276,794 Ricci Mar. 17, 1942 2,309,591 Horton Ian. 26, 1943 2,395,657 Dinsmorer Feb. 26, 1946 2,408,851 Hillier et al. Oct. 8, 1946 2,409,931 Curtis Oct. 22, 1946 2,427,674 Holthouse Sept. 23, 1947 2,865,355 Hilton Dec'. 23, 1958 2,867,269 Bayer Jan. 6,1959 2,944,488 Meyer July 12, 1960