US3794005A - Fluidic fuel injection system utilizing simplified fluidic computation element - Google Patents

Abstract

Fluidic computation is simplified in a system wherein one of plural input parameters is a fluid flow which is to be multiplied by the sum of the other parameters. The primary computation element is a parallel flow sensor in which a fluid sensing jet is issued from within and parallel to the fluid flow and is received as a linear function of the fluid flow. The effects of other input parameters are included by utilizing each to vary the supply pressure for the sensing jet to thereby sum the effects of these parameters and multiply the sum by the fluid flow. In a preferred embodiment, the computation element is utilized in a fluidic fuel injection control for an internal combustion engine wherein the fluid flow is air flow through the intake manifold and the other input parameters include fuel-to-air ratio, inlet air pressure, inlet temperature and engine temperature. The resulting output signal represents the required fuel flow which is then modified by fluidic circuitry to deliver the proper quantity of fuel per cylinder stroke.

Description

United States Patent Turek i 1 FLUIDIC FUEL INJECTION SYSTEM UTILIZING SIMPLIFIED FLUIDIC COMPUTATION ELEMENT Robert F. Turek, Silver Spring, Md.

Bowles Fluidics Corporation, Silver Spring, Md.

Filed: Sept. 17, 1971 Appl. No.: 181,531

lnventor:

Assignee:

US. Cl. 123/119 R, 137/815 Int. Cl. F02m 69/00 Field of Search.. 123/DIG. 10, 119 R, 139 AC;

References Cited UNITED STATES PATENTS Primary Examinef-Laurence M. oodridge Attorney, Agent, o FTiiih -R ose 8L Edll Feb. 26, 1974 5 7 ABSTRACT Fluidic computation is simplified in a system wherein one of plural input parameters is a fluid flow which is to be multiplied by the sum of the other parameters. The primary computation element is a parallel flow sensor in which a fluid sensing jet is issued from within and parallel to the fluid flow and is received as a linear function of the fluid flow. The effects of other input parameters are included by utilizing each to vary the supply pressure for the sensing jet to thereby sum the effects of these parameters and multiply the sum by the fluid flow. In a preferred embodiment, the computation element is utilized in a fluidic fuel injection control for an internal combustion engine wherein the fluid flow is air flow through the intake manifold and the other input parameters include fuel-to-air ratio, inlet air pressure, inlet temperature and engine temperature. The resulting output signal represents the required fuel flow which is then modified by fluidic circuitry to deliver the proper quantity of fuel per cylinder stroke.

8 Claims, 9 Drawing Figures F LUIDIC FUEL INJECTION SYSTEM UTILIZING SIMPLIFIED FLUIDIC COMPUTATION ELEMENT BACKGROUND OF THE INVENTION The present invention relates to fluidic computation elements, and more particularly to a fluidic computation element having particular utilization in a control apparatus for internal combustion engines.

Increased public concern about air pollution has resulted in governmental regulations being imposed in many countries for the purpose of limiting the allowable contaminating emissions from motor vehicles. The regulations become more stringent with each passing year and by 1975 substantially pollution-free vehicles will be required.

In order for the internal combustion engine to retain its usefulness in a pollution free environment, it is necessary that an efficient approach to fuel injection be developed. Prior art fuel injection systems have been utilized in the past but require complex computation apparatus to compute the required fuel flow from various sensed engine parameters. The complexity, and resulting expense, of prior art fuel injection systems have rendered such systems impracticable for commercial use. Consequently, fuel injection systems have been used in the past only where special performance is desired, as in sport or racing cars, or as an option for luxury cars. lf the internal combustion engine is to remain useful, a low cost fuel injection system for all production cars must be developed.

It is therefore one object of the present invention to provide a low cost and relatively simple fuel injection control apparatus.

Methods of computing engine fuel requirements may be divided into two general classes; direct, and indirect. The conventional methods are all indirect. The system of the present invention is direct because it measures the most irn portant engine variable, air flow.

All conventional systems require complex, non-linear functions of two variable. Thus, conventional mechanical computers use 3- di rnensional earns, analog computers (either electronic or fluidic) use very complex circuits of active, passive, linear and non-linear components, and in digital computers, large numbers of memory units are required. In contrast, the direct approach permits a simple design using a non-linear function of only one variable. This function, if properly selected, permits other measured engine parameters to simply modify the function with simple computing functions. As described in the detail herein, the one variable selected is fuel-to-air ratio, and the non linear function is the relationship between engine load and fuel-to-air ratio.

Fluidics technology, by its very nature, lends itself to utility in fuel metering systems. This technology, as is now well known, involves the control of fluid streams by means of pressures or other fluid streams to effect amplification or switching without moving parts. Several fluidics control system approaches, which have been developed for other applications and which appear on the surface to be useful for fuel injection control, cannot in fact be utilized for fuel injection. The major limitation in this regard is the fact that the inputoutput characteristics of fluidic elements are not precisely repeatable in elements which are mass produced in large quantities. Therefore, highly accurate performance must be achieved with accurate passive components which can be manufactured with more consistent performance characteristics. Thus, a number of prior art approaches to fuel metering with the aid of fluidics appear promising on the surface but suffer from lack of repeatability in operational characteristics from unit to SUMMARY OF THE INVENTION In accordance with the present invention, the air flow in the intake manifold is measured by means of parallel flow sensor in which a sensing jet is issued in the manifold towards a receiver in a direction parallel to manifold air flow. Viscous interaction between the manifold air flow and sensing jet produce variations in the jet pressure at the receiver as a liner function of manifold air flow variations. The supply pressure for the sensing jet is itself rendered variable in response to manifold inlet air pressure and temperature, engine temperature, and the computed fuel-to-air ratio which is derived by means of a fluidic function generator circuit as a nonlinear function of the intake manifold pressure. The effect of varying the sensing jet supply pressure in response to these parameters is the summation of these parameters and multiplication of this sum by the manifold air flow. The resulting pressure signal at the jet receiver represents the required fuel flow. This signal is then fluidically divided by engine speed to produce a signal representative of fuel quantity required per engine stroke. The latter controls the fuel pump to feed the proper amount of fuel to the engine during each engine stroke, thereby optimizing engine efficiency and minimizing emission of air pollutants.

BRIEF DESCRIPTION OF THE DRAWINGS The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of specific embodiments thereof, especially when taken in conjunction with the accompanying drawings, wherein:

FIG. I is a functional block diagram of a fuel injection system according to the present invention;

FIG. 2 is a sectional view of an intake manifold taken along lines 2-2 in FIG. 1;

FIG. 3 is a timing diagram illustrating the waveforms of signals at various points in the block diagram of FIG.

FIG. 4 is a scheatic diagram schematic a fluidic fuel flow computer utilized in the system of FIG. 1;

FIG. 5 is a schematic diagram of a fluidic fuel-air ratio function generator utilized in the system of FIG.

FIG. 6 is a schematic diagram of a fluidic fuel flowper-stroke circuit utilized in the system of FIG. 1;

FIG. 7 is a schematic diagram of a fluidic actuator stroke control utilized in the system of FIG. 1;

FIG. 8 is a schematic diagram of a fluidic idle governor utilized in the system of FIG. 1; and

FIG. 9 is a schematic diagram of a fluidic governor vortex throttle amplifier utilized in the system of FIG. l.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1 of the accompanying drawings there is illustrated a fluidic fuel injection control system employing the principles of the present invention. The intake manifold M) of an internal combustion engine receives air inflow fromair filter 11. The air supply for the fluidic control circuits described below comprises an air pump 1 and regulator 2. The source for the air pump comes from the ambient portion of intake manifold 10, after the air has been filtered by air filter ll. Regulator 2 also utilizes the manifold inlet pressure as a reference instead of atmospheric pressure. This provides the air flow sensor, described below, with a supply pressure accurately referenced to the static pressure in the flow sensing region. Although no direct connection is illustrated in the drawings, the regulated output pressure P+ from air pump ll serves as a supply for all fluidic elements in the system.

Air flow is sensed by means of a parallel flow sensor including supply nozzle 13 andreceiver tube 15 disposed within the intake manifold 10. The parallel flow sensor is of the type disclosed in my co-pending US. Pat. application Ser. No. 36,627, filed May 12, 1970, and entitled Fluidic Flow Sensing Techniques. The flow sensor operates by issuing a flow sensing jet M of pressurized fluid, in this case air, in a direction generally parallel to the flow being monitored, in this case the intake manifold air flow. For this purpose nozzle 13 is emersed in and axially aligned with the direction of manifold air flow. Likewise,receiver 15 is positioned to receive a portion ofjet 14 which does not include the constant pressure central core of the jet. The portion of the jet thus received atreceiver tube 15 is subjected to pressure changes resulting from flow variations in the manifold air flow, since manifold air flow is viscously coupled to sensing jet M. Importantly, the parallel flow sensor employed herein provides a signal atreceiver 15 which is a linear function of air flow variation in the manifold. Moreover, the quiescent pressure (i.e., at zero manifold air flow) is raised to a workable level by virtue of sensingjet 14 so that even relatively low manifold air flow can be sensed by the described parallel flow sensor without the need for ultra-sensitive low pressure detection devices.

Referring to FIG. 4, the supply pressure P+ for nozzle 13 is delivered through fixed flow restrictor A connected in series with variable flow restrictor A The output pressure fromreceiver tube 15 is designated P and, as mentioned above, varies in proportion to manifold air flow. The supply pressure for nozzle 13 is also supplied to series connected fixed flow restrictions A, and A the latter being referenced to manifold 10. Flow restrictors A, and A are selected to render the pressure R, at the junction between these two restrictors equal to pressure P when air flow through manifold is zero. Thus the pressure difference AP between P and P is nulled for zero air flow in manifold l0 and varies proportionally with air flow in manifold It).

As described below, modification of the supply pres sure at nozzle 13 is the means utilized for introducing the effects of fuel-to-air ratio, engine temperature, manifold temperature and manifold air density at the air flow sensor. AP is in this way modified to provide the required fuel flow signal for controlling the amount of fuel injection. Importantly, the introduction of these effects, their summation, and the multiplication of the sum by the air flow signal, is achieved right at the flow sensor. In this regard, a signal representing air flow per se (unmodified) does not actually exist; nor does a separate fuel-to-air ratio signal exist except as an implicit component in the pressure supplied to nozzle 13.

One of the parameters employed to modify the sensor supply pressure is the fuel-to-air ratio which is derived from the manifold pressure, P,,,. This static pressure in the manifold, sensed downstream ofmanifold throttle valve 17, is a measure of engine load and is applied directly to the fuel-air ratio function generator of FIG. 5. Thus function generator is an active fluidic circuit which produces an output pressure signal P as a non-linear function of P The P pressure signal is the raw fuel-to-air ratio signal and is utilized to vary the supply pressure to the flow sensor as a function of fuelto-air ratio. The manifold pressure signal P is applied through a series of orifice-type flow restrictors A and in turn to orifice restrictor A which is referenced to supply pressure P+. The signal P at the junction between restrictor A and restrictors A varies in proportion to signal P,, and is always above atmospheric'pressure in order to serve as a control signal for afluidic amplifier 18. The reason for a multiple orifice network comprising restrictors A and A is to prevent sonic flow in the path between P and P sonic flow, if it were to exist in this path, would permit P to remain constant as P varies.Fluidic element 18 is a proportional fluidic amplifier utilized in producing the required non-linear function of input signal P A constant bias pressure, acting in opposition to P,,,' atelement 18, is generated by supply pressure P+ in conjunction with restrictor A The output passages ofelement 18 include respective fixed flow restrictors A and A the output sizes of which are chosen to provide the desired output versus input characteristic. Specifically, P should be low for mid-range values of manifold pressure P and high for both low and high values of manifold P More specifically, the desired shape of the P versus P characteristic is obtained by properly adjusting and selecting restrictors A, and A Techniques for employing orifice type restrictors in conjunction with fluidic elements for the purpose of curve shaping are described in US. Pat. No. 3,250,469 to Colston and U.S. Pat. No. 3,398,759 to Rose. Signal P is applied through pressure isolating restrictor A to the junction between restrictors A and A where it forms a component of the supply pressure applied to nozzle 13.

Also effecting the supply pressure applied to nozzle 33 is the engine temperature which is sensed by abimetal sensor 19 illustrated in FIG. 1. Movement ofbimetal sensor 19 in response to temperature changes in the engine adjusts the opening of adjustable bleed valve A The latter is connected between ambient and the junction between restrictors A and A More specifically, increasing engine temperature produces an increase in the bleed area provided by valve A thereby lowering the supply pressure for the flow sensor. The

primary purpose of sensing the engine temperature is to permit an enriched fuel-to-air ratio during engine warm up.

A similar arrangement is utilized to introduce the ef fect of manifold air temperature and is best illustrated in FIGS. 1 and 4. Specifically, a bi-metal sensor 21 (FIG. 1) senses the air pressure at the manifold inlet and controls the bleed orifice in valve A (FIG, 4) accordingly. Valve A is connected between ambient and the junction between restrictors A and A The purpose of introducing the effect of manifold air inlet temperature is to compensate the air flow sensor for changes in inlet air density produced by variations in air temperatures. Air density, of course, affects the fuel-air mixture and therefore must be considered when computing the fuel flow required for optimum fuel-to-air ratio.

Restrictor A is of itself variable as a function of the position of aneroid or bellows sensor 23 (FIG. 1). The latter is positioned to expand or contract in response to the manifold inlet air pressure P,. Signal P, is employed to compensate the air flow sensor for changes in inlet density due to altitude changes or pressure losses in air cleaner 1 1.

The various signals described above are utilized to vary the supply pressure for nozzle 13 either by changing the value of a passive loading orifice in the supply circuit or by varying a pressure in the supply circuit with an active element. Each in its own way adds to or subtracts from the supply pressure for the air flow sensor to produce an effect on the sensor output signal AP. Since AP varies as a function of the sensor supply pressure, the summed effect of the four supply pressurevarying parameters is multiplied by the manifold air flow sensed atreceiver 15.

Signal AP is applied between opposed control ports of proportional fluidic amplifier 25.. As indicated by the dashed lines between amplifier 25 andamplifier 27 in FIG. 4, a plurality of cascaded proportional fluidic amplifiers may be employed for the purpose of amplifying AP. The last stage in the group of cascaded amplifiers isamplifier 27 which provides a single ended pressure signal P The pressure signal P is an amplified version of AP and represents the product of fuel-to-air ratio multiplied by measured air flow as compensated by other engine parameters. P is thus at a pressure level representative of the required fuel flow. The actual gain function for the amplifier arrangement in FIG. 4 is determined by the ratio of feedback restrictor R to input restrictor R, in a manner well known for operational amplifiers.

The fuel flow signal P,, is applied to the fuel flow per stroke circuit of FIG. 6 which functions to divide P by engine speed to obtain a fuel flow per stroke signal P-,. The circuit includes an operational amplifier 31 comprising a plurality of cascaded proportional amplifiers having as an input signal P The input terminal to the operational amplifier is also connected to a fluidic capacitor (storage volume) V The non-inverting output terminal of operational amplifier 31 provides a signal P, which is applied through a fluid diode gate arrangement to an output capacitor V The diode gate comprises a series diode D poled to conduct flow from the output terminal of the amplifier to capacitor V Also included are a pair of series connected diodes D and D poled in opposite directions, the series arrangement in parallel with D Diodes D D and D are preferably rubberized check valves which completely cut off the flow in one direction and pennit relatively unimpeded flow in the other direction.

A control signal P is applied to the junction between diodes D and D through orifice restrictor A Another control signal P is operatively connected to the input terminal of operational amplifier 31 by means of diode 1D,, the latter being poled to conduct flow from the input terminal of the amplifier toward the source of P The P and P signals are timing pulses generated by a synchronizer such as the type schematically illustrated in FIG. 1. More particularly, the synchronizer includes adrum 32 which is caused to rotate at onehalf the engine rotational speed. Interiorly of the drum is a manifold tubing 33 containing pressurized air which is directed radially outward toward the drum periphery by means of angularly spacedjet nozzles 34, 36, etc.Receiver tubes 35, 37, etc. are disposed about the drum periphery in alignment withrespective jet nozzles 34, 36, etc., to receive pressurized fluid therefrom through an appropriately provided slot in the peripheral wall ofdrum 32. A small portion of this slot is blocked by a fluidimpervious member 38 which rotates with the drum and momentarily interrupts flow of pressurized air from each jet nozzle to its aligned receiver tube in sequence. Thus, asmember 38 passes betweenjet nozzle 34 andreceiver tube 35, the pressure P inreceiver tube 35 is momentarily reduced to substantially zero. Likewise whenmember 38 passes between jet nozzle 36 and receiver tube 37, the pressure P in receiver tube 37 is momentarily reduced to zero. P and P may therefore be considered timing pulses, each being repeated once each cycle ofdrum 32.Drum 32 can be linked to the engine cam shaft or distributor shaft as necessary to produce the required synchronized rotational speed at one half that of the engine.

The operation of the circuit of FIG. 6 may now be understood with reference to the wave forms illustrated in FIG. 3. The output signal P from amplifier 31 has a sawtooth wave form which is initiated each cycle to discharge capacitor V,. Upon termination of P V, begins charging under the control of input signal P through resistor 2R The combination of resistor 2R and capacitor V form an integrating circuit which in effect renders the slope of the charging portion of signal P proportional to the input signal pressure P This may be represented mathematically by equation (1) as follows:

wherein K, is a constant of proportionality dependent upon the values of 2R and V, and the gain of amplifier 31.

Since the frequency of timing pulse P is proportional to engine speed, the period of duration of the charging cycle of V is inversely proportional to engine speed. This period, At may be represented mathematically by equation (2) as follows:

(2) wherein K is a constant of proportionality and N is the frequency of rotation ofdrum 32.

P which is merely an amplified version of the pressure in capacitor, V has a value at the end of each charge cycle which is proportional to the input signal P divided by engine speed. More specifically, since P increases linearly with time at a rate K P per unit time, the value of P at the end of A t units of time may be represented by equation (3) as follows:

The value of P at the end of eaph cycle is sampled and held by the diode gating cir cuit and capacitor V More particularly the end of each charging cycle is designated by the occurrence of negative going pressure pulse P The pressure at the junction of diodes D and D is normally high, preventing diodes D and D. from conducting. Once each cycle, timing pulse P lowers the pressure at the junction of diodes D and D to permit the latter two diodes to conduct, if proper pressure conditions exist. Thus, if the peak value of P is increasing, diode D conducts flow into capacitor V Signal P which is the pressure of capacitor V thus represents the peak value of P If this peak value is decreasing, flow from capacitor V is discharged through diode D each time timing pulse P occurs. After P has decreased to the new lower value of P diode D is rendered conductive to flow. This terminates discharge through diode D thereby causing the new value of P to equal P The circuit of FIG. 6 effectively divides required fuel signal, P by the engine speed to provide signal P representing the required fuel per stroke. Signal P, is in turn applied to the actuator stroke control circuit of FIG. 7 which includes ahigh gain amplifier 41 compris ing a plurality of cascaded proportional fluidic amplifiers. The output stage of amplifier All drives ashaft 42 by means of abellows arrangement 43,shaft 42 being linked mechanically at 44 to drive afurther shaft 46 which varies the volumetric displacement offuel injection pump 45. Acam surface 48 onshaft 42 is angled to vary its proximity to an orifice restrictor A as a linear function of the position ofshaft 42. Pressurized air, delivered from the P+ supply through restrictor A is issued from orifice A The pressure P, upstream of orifice l6 varies as a function of the proximity ofcam surface 48 to the downstream end of orifice A Signal P is fed back through a flow divider comprising restrictors R and R, as a negative feedback signal to the input stage ofamplifier 41.

The feedback signal P, is a function of the area ratio of A /A The shape of the area versus stroke function is contoured to provide correct relationship between signal P and the actual effective pump displacement and, of course, depends upon the pump characteristics. The areas of restrictors A and A may be chosen to provide this relationship.

The system as thus far described is operative to inject the proper amount of fuel per stroke into the cylinders of an internal combustion engine as the engine load varies. The fuel flow computer circuit of FIG. 4 computes the desired fuel flow rate for measurements for various conditions of the engine and the environment. The fuel flow per stroke circuit of FIG. 6 computes the required fuel charge per stroke by'dividing the computer fuel flow rate, as represented by signal P by the engine speed, N. The actuator stroke control circuit of FIG. 7 controls the effective volumetric displacement of the cylinder injection pump by controlling the mechanical input position of the pump as a function of the fuel per stroke signal P,. The control system arrangement illustrated and described above is not dependent upon repeatability of operational characteristics of fluidic elements; rather the fluidic elements themselves are employed as adaptable components of control arrangements. Precise determination of circuit characteristics is provided by passive components such as the various restrictors and capacitors described.

An idle governor arrangement, effective under engine idle conditions to provide accurate control of idle RPM, includes the idle governor circuit of FIG. 8 and the governor vortex throttle amplifier of FIG. 9. The idle governor circuit comprises a charging volume or capacitor V which receives pressurized air from the system air supply through restrictor A The junction between A and V is connected to a diode D poled to conduct flow away from the junction. The downstream end of diode D is connected to receive the negative-going P timing pulse. The output of capacitor V is connected through a flow restrictor to the control port of a fluidic OR/NOR gate 5Gate 51 provides a positive pressure output signal at itsoutput terminal 52 when the input signal to its control port exceeds a predetermined positive pressure threshold.Output leg 52 ofgate 51 feeds capacitor V., which in turn provides an output signal designated P The latter increases in amplitude as the actual engine speed falls below a predetermined idle setting. P remains constant at a value of zero when the engine speed remains above idle.

The circuit of FIG. 8 operates as follows: between timing pulses P capacitor V charges through restrictor A The pressure P at the control port ofgate 51 increases slowly as V charges. At the occurrence of each negative going pressire pulse P capacitor V discharges completely through the high speed discharge circuit comprising diode D,,. As the engine speed decreases, the interval between pulses P increases, thereby permitting the pressure P to build up to a higher value between capacitor discharge times. The charging time constant of capacitor V is selected to permit P to reach the threshold ofgate 51 when the engine speed falls to idle.Gate 51 thus switches to provide an output pressure pulse inpassage 52, the pulse terminating when the next timing pulse P discharges capacitor V If the speed decreases further, the width of the pulse delivered to capacitor V in each cycle increases. This increasing pulse width increases the average value of the pressure in capacitor V which average pressure is designated I V th s t nd 2. w siii sinil P .1. an u I increase s as the engine speed falls bel o w idle.

Signal P dbmprises aninpdt signal for the governor vortex throttle amplifier of FIG. 9. This amplifier is simply a plurality of cascaded proportional fluidic amplifiers designated 53 and provides a differential output flow signal q,-q as a function of the amplitude of P The signals q and q are delivered to manifold 10 (FIG. l) in a manner so as to cooperate withbutterfly valve 17 to provide a simple vortex air flow throttle. More particularly,butterfly valve 17 includes asmall hole 19 which is sized to provide the maximum idle air flow required by the engine; this maximum air flow occurs during warm up of the engine on a cold day. A typical size of such a hole would be 0.184 inches, but would vary depending upon the nature of the engine. Signal q is introduced tangentially into cylindrical manifold M) at a location upstream ofbutteryfly valve 17. Signal q is introduced radially into manifold 10, also at a location upstream ofvalve 17. When P is zero, indicating that the engine speed is above idle, q,, the tangential control for the vortex valve is at maximum pressure. The tangential inflow to the manifold provided by q causes a high degree of vorticity in the air flow attempting to pass valve 117. This vorticity effects a throttling action and limits the manifold air flow to a relatively low value. By way of example only, the throttling action at maximum value of q, would reduce the air flow in manifold to one-third its maximum value.

As the engine speed is lowered, the tangential flow q is lowered accordingly and the radial flow g is increased. The vortex throttling action is therefore reduced and air flow through the manifold is increased. It will be evident that, for throttling reduction, it is not necessary to introduce the non-tangential flow q into the vortex region to increase air flow; rather, merely minimizing the tangential flow is sufficient to reduce the throttling action in the manifold.- The radial or nontangential flow is introduced however to keep a constant control flow (q q a constant) into the manifold. This flow is not sensed by the air flow sensor because of its downstream location but, because the total is constant, a fixed bias can be utilized in the air flow sensor.

The disclosed fuel injection control system has a number of advantages. One advantage is its simplicity which results from the utilization of a fluidic air flow sensor which, in turn, permits direct measurement of the primary engine input parameter: air flow. The computation of the required fuel flow using the measured air flow directly is far simpler than computations in the prior art.

The disclosed control system also has the advantage of flexibility in that it is easily adapted to many engines.

Another advantage of the disclosed system is the fact that it permits precision fuel metering. The inclusion of a conventional metering pump and injectors takes maximum advantage of existing and proven engine knowhow. This, coupled with an inherently correct computing approach, provides precise control of fuel-to-air ratio at each cylinder.

The basic computation element, namely the fluidic flow sensor having a parameter controlled supply pressure, has utilization in areas other than fuel injection, as long as plural parameters, including flud flow, are involved in the computation.

While I have described and illustrated specific embodiments of my invention, it will be clear that variations of the details of construction which are specifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims.

I claim:

1. A fluidic computation element for use in a system wherein an output signal is required as a function of the product of a fluid flow multiplied by at least one additional parameter, said computation element comprising:

a source of pressurized fluid;

a nozzle connected to receive pressurized fluid from said source and positioned in said fluid flow to issue a sensing jet of said pressurized fluid parallel to and within said fluid flow;

a receiver positioned within said fluid flow to receive a portion of said sensing jet having a pressure which varies with said fluid flow, said receiver providing said output signal; and

control means for varying the pressure of the pressurized fluid connected to said nozzle as a function of said additional parameter;

wherein said fluid flow is the air flow in an intake manifold of an internal combustion engine, and wherein said additional parameter is a parameter of said engine.

2. The element according to claim 1 wherein said control means comprises means for supplying a pressure signal in summing relationship with the pressurized fluid from said source, said pressure signal being variable as a function of said engine parameter.

3. The element according to claim 1 wherein said control means includes means for bleeding pressurized fluid connected to said nozzle as a function of said engine parameter.

4. The element according to claim 1 wherein said control means comprises:

means for providing a control pressure which varies in proportion to said engine parameter;

a fluidic circuit for providing a pressure signal which varies as a predetermined non-linear function of said control pressure, and

means for summing said pressure signal with the pressurized fluid from said source connected to said nozzle.

5. The element according to claim 1 wherein said output signal is required as a function of the product of said fluid flow multiplied by the sum of said one engine parameter and at least a second engine parameter, said element further comprising:

means for generating a pressure signal as a function of said one engine parameter;

means for summing said pressure signal with the pressure of said pressurized fluid connected to said nozzle; and

means for bleeding pressurized fluid connected to said nozzle at a rate which is a function of said second engine parameter.

6. A fuel injection control system for an internal combustion engine having an air intake manifold, said control system comprising:

first means for directly measuring air flow in said intake manifold;

second means for sensing engine load;

third means responsive to the sensed engine load for providing a first signal having an amplitude representing optimum fuel-to-air ratio required by the engine for the sensed load; and

fourth means responsive to said first signal and the measured air flow for providing a further signal representing the required fuel flow, said further signal having an amplitude which varies as function of the product of the measured air flow and the required fuel-to-air ratio for the sensed engine load;

wherein said first means comprises a fluidic parallel flow sensor including:

a nozzle arranged to receive pressurized air and issue a sensing jet within and parallel to the air flow in said intake manifold; and

a receiver arranged to receive a portion of said sensing jet in which the pressure varies in proportion to the manifold air flow;

wherein:

said second means includes means for providing a load pressure which varies in proportion to the sensed load;

said third means comprises a fluidic function generator for providing said first signal at a pressure which a predetermined non-linear function of said load pressure; and

said fourth means includes means for adding the pressure of said further signal to the pressure received by said nozzle.

7. A fuel injection control system for an internal combustion engine of the type having an air intake manifold and a fuel injection pump with a controllable volumetric displacement for its fuel stroke, said system comprising:

a parallel flow sensor for directly measuring air flow in said intake manifold, said parallel flow sensor comprising:

a source of pressurized fluid;

a nozzle connected to receive pressurized fluid from said source and positioned to issue a sensing jet of said pressurized fluid within and parallel to the air flow in said intake manifold; and

a receiver positioned within the air flow in said intake manifold to receive a portion of 'said sensing jet having a pressure which varies with the velocity of said air flow;

means for sensing engine load; 7

means responsive to the sensed engine load for varying the pressure of fluid in said source of pressurized fluid and thereby varying the pressure of said sensing jet; and

fluidic amplifier means responsive to the pressure of the portion of said sensing jet received by said receiver for controlling the volumetric displacement of said fuel injection pump.

8. The fuel injection control system according to claim 7 further comprising:

means for providing a fluid signal having a parameter which varies as a function of the speed of said engine; and

means responsive to said parameter of said fluid signal for varying the gain of said fluidic amplifier means as a function of the speed of said engine.

Claims (8)

1. A fluidic computation element for use in a system wherein an output signal is required as a function of the product of a fluid flow multiplied by at least one additional parameter, said computation element comprising: a source of pressurized fluid; a nozzle connected to receive pressurized fluid from said source and positioned in said fluid flow to issue a sensing jet of said pressurized fluid parallel to and within said fluid flow; a receiver positioned within said fluid flow to receive a portion of said sensing jet having a pressure which varies with said fluid flow, said receiver providing said output signal; and control means for varying the pressure of the pressurized fluid connected to said nozzle as a function of said additional parameter; wherein said fluid flow is the air flow in an intake manifold of an internal combustion engine, and wherein said additional parameter is a parameter of said engine.

2. The element according to claim 1 wherein said control means comprises means for supplying a pressure signal in summing relationship with the pressurized fluid from said source, said pressure signal being variable as a function of said engine parameter.

3. The element according to claim 1 wherein said control means includes means for bleeding pressurized fluid connected to said nozzle as a function of said engine parameter.

4. The element according to claim 1 wherein said control means comprises: means for providing a control pressure which varies in proportion to said engine parameter; a fluidic circuit for providing a pressure signal which varies as a predetermined non-linear function of said control pressure, and means for summing said pressure signal with the pressurized fluid from said source connected to said nozzle.

5. The element according to claim 1 wherein said output signal is required as a function of the product of said fluid flow multiplied by the sum of said one engine parameter and at least a second engine parameter, said element further comprising: means for generating a pressure signal as a function of said one engine parameter; means for summing said pressure signal with the pressure of said pressurized fluid connected to said nozzle; and means for bleeding pressurized fluid connected to said nozzle at a rate which is a function of said second engine parameter.

6. A fuel injection control system for an internal combustion engine having an air intake manifold, said control system comprising: first means for directly measuring air flow in said intake manifold; second means for sensing engine load; third means responsive to the sensed engine load for providing a first signal having an amplitude representing optimum fuel-to-air ratio required by the engine for the sensed load; and fourth means responsive to said first signal and the measured air flow for providing a further signal representing the required fuel flow, said further signal having an amplitude which varies as function of the product of the measured air flow and the required fuel-to-air ratio for the sensed engine load; wherein said first means comprises a fluidic parallel flow sensor including: a nozzle arranged to receive pressurized air and issue a sensing jet within and parallel to the air flow in said intake manifold; and a receiver arranged to receive a portion of said sensing jet in which the pressure varies in proportion to the manifold air flow; wherein: said second means includes means for providing a load pressure which varies in proportion to the sensed load; said third means comprises a fluidic function generator for providing said first signal at a pressure which is a predetermined non-linear function of said load pressure; and said fourth means includes means for adding the pressure of said further signal to the pressure received by said nozzle.

7. A fuel injection control system for an internal combustion engine of the type having an air intake manifold and a fuel injection pump with a controllable volumetric displacement for its fuel stroke, said system comprising: a parallel flow sensor for directly measuring air flow in said intake manifold, said parallel flow sensor comprising: a source of pressurized fluid; a nozzle connected to receive pressurized fluid from said source and positioned to issue a sensing jet of said pressurized fluid within and parallel to the air flow in said intake manifold; and a receiver positioned within the air flow in said intake manifold to receive a portion of said sensing jet having a pressure which varies with the velocity of said air flow; means for sensing engine load; means responsive to the sensed engine load for varying the pressure of fluid in said source of pressurized fluid and thereby varying the pressure of said sensing jet; and fluidic amplifier means responsive to the pressure of the portion of said sensing jet received by said receiver for controlling the volumetric displacement of said fuel injection pump.

8. The fuel injection control system according to claim 7 further comprising: means for providing a fluid signal having a parameter which varies as a function of the speed of said engine; and means responsive to said parameter of said fluid signal for varying the gain of said fluidic amplifier means as a function of the speed of said engine.

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