DE2365088A1 - Fuel injection system for IC engines - alters fuel injection pressure to suit working requirements - Google Patents

Abstract

The fuel circuit is provided with a fuel pressure accumulator (28) preferably topped close to a fuel injector to give a signal corresponding to current fuel pressure. This signal is fed to a comparator (44) which also receives a signal from an engine revolution counter. The signals are compared electronically and the difference is used to modify the fuel pressure accordingly.

Description

Patent attorneys Dipl.-Ing. F. X- ⁷ LiC · ι minist, '2365088

Dipl.-Ing. H.Weickmann, Dipl.-Phys. Dr. K. Fincke Dipl.-Ing. F. AAYeickmann, Dipl.-Chem. B. Hu3er

8 MUNICH 86, DEN

BOX 86C820

MÖHLSTRASSE 22, CALL NUMBER 98 39 21/22

JKY / Uo

Pesics international company
San Leandro, California. V.St.A.
2700 Merced Street

Arrangement for fuel injection "with an internal combustion smot or

The invention "relates to an arrangement for fuel injection "in an internal combustion engine with one fuel injection valve for each cylinder and one common Feed line for feeding fuel into the fuel injection valves.

Fuel injection systems are normally used to to effect the introduction of liquid fuel into the intake runners or cylinders of internal combustion engines. In one of these systems, a mechanically operated pump is used to bring the fuel to injection pressure bring to. A pressure control valve is used to control the Monitor fuel pressure in a common feed line, so that it is kept at a constant value, while excess fuel is returned to the pump inlet. Injection fuel fed from the common line

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valves then operate sequentially for a period of time opened by the operating requirements of the engine to regulate the injected at constant injection speed The amount of fuel depends on * In Otto (igniter) engines there is a throttle ratio of approximately 4: 1 between the fuel for maximum and minimum at any speed Load Required It has been found to be beneficial in reducing toxic emissions from gasoline engine exhaust proven to make the injection during the time in which the intake valve of the engine is open. As for injection within the intake period at maximum speed usually only 5 "to 6 msec are available, the minimum load at all speeds requires a minimum injection duration from 1 # 25 to 1.5 msec, since the duration the only available control parameter is “Such a short injection duration is with electromagnetic or mechanical operated injectors difficult to achieve * Very short Injection intervals result in inconsistent fuel regulation in these valves, which is necessary for high speeds could still be accepted, but with idle and extra idle (off idle) conditions are no longer acceptable.

In diesel engines, a constant common rail pressure results in a constant fuel injection rate. The injection rate required to inject maximum fuel at high RPM (revolutions per minute) must be tolerated even at low RPM. Excessive diesel knock then occurs for the following reasons. Diesel fuel has an injection delay period is approximately constant and independent of engine speed "When fuel is injected at an excessive rate, check is the entire Fuel level within the cylinder and undergoes overall Zündverzögerungsphase _e Efach release of heat then burns the entire Millung almost instantaneously and creates such a rapid increase in pressure

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and heavy knocking. It would be more desirable to have the fuel to be injected at low speeds at a low rate, so that only a small part of the filling enters the ignition ■ delay phase fully experiences and most of the fuel at a rate controlled by the injection rate burns. Fuel injected after the first injected fuel has released heat, then burns almost immediately after its injection, according to the greater rate of reaction at higher temperature, such as it is described by the Arhennius relationj the speed the increase in pressure can then be controlled by the injection rate.

As a result, even if you have a pilot injection (auxiliary injection) used, a variable injection rate of the main injection is desired in order to avoid pressure increase, peak pressure, Control noise, nitrogen oxide formation, and other effects associated with high cylinder pressures and temperatures are.

The object of the present invention is to create an arrangement for fuel injection that has a regulation the fuel pressure in a common feed line of an internal combustion engine in accordance with changes in predetermined engine parameters, especially the Engine speed or the amount of air taken in, permitted * The arrangement should be based on the specified motor parameters can react in particular with a rapid rise or fall in pressure. This object is achieved according to the invention in that in an arrangement of the type mentioned at the outset for changing the fuel pressure according to a freely specified parameter of the engine, a first and a second converter circuit are provided, the first converter circuit being one of the fuel pressure in the common feed line dependent voltage (first voltage) and the second converter circuit one of the free

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predetermined motor parameter dependent voltage (second voltage) generates. that a potentiometer circuit raises the second voltage to the nth power, where η is an adjustable factor whose Y / ert is determined by a freely specified motor tuning, and a voltage ( third voltage) which represents a desired fuel pressure, that a comparator circuit compares the first and the third voltage with one another and determines the greater of the two and their difference and that the arrangement contains a controller which, depending on the output signal of the comparator circuit, the fuel pressure in the common feed line changes at a rate determined by the difference until the fuel pressure assumes the value determined by the third voltage _β ~

An arrangement according to the invention works according to the following principle: The pressure in the common line is determined by a pressure control valve which is controlled so that the pressure in the common line can increase or decrease depending on the output of a pump. The pump in turn works as a function of an engine parameter, for example the engine speed. For these dependencies there is the calculated relationship pr -> (RPM) ⁿ , where RPM is the engine speed, the factor η is an index (exponent) specified by coordination and ρ is the calculated fuel pressure

ρ is. The index η may be taken from the BernuoHi relation - " with ν as the velocity of the flow through an opening under the pressure p. In practical However, systems deviate from this theoretical relationship due to viscosity effects with low Reynolds numbers, eddy losses and other irreversible ones Processes. The Bernuolli index 2 is therefore seldom exactly achieved in practice, in practice Calibration tests, the arrangement must be corrected for the deviations "

5098477 001.1

The pump is operated so that it works with increasing engine speed the pressure control valve causes less and less Circulating fuel in the common rail, thereby increasing the pressure; with decreasing engine speed it allows the pressure control valve to circulate more fuel and thus reduces the pressure. The engine speed is converted into an analog form and used to calculate a theoretically correct pressure. The actual fuel pressure in the common rail is measured and compared with the calculated pressure. Any difference is used to control an electromechanical actuator used to cause the pressure regulating valve to reduce the fuel pressure in the common rail to the to increase or decrease the calculated value. If the fuel pressure is regulated proportionally to (RPM) ~, for example the opening time of the valve for a constant fuel filling per engine cycle changes inversely proportional to Mo ~ gate speed (equivalent to a constant angle of rotation the crankshaft; this means longer ones at low speeds Opening periods possible, which result in a more precise fuel regulation «

Further features and details of the invention emerge from the claims. management example in connection with the figures of the drawing are explained in more detail. Show:

Fig _# 1: as a purely schematic block diagram, an arrangement according to the invention, which is used in diesel engines. can be turned;

Fig * 2: a as a pump in an arrangement according to the invention suitable actuator;

Fig. 3: a suitable for an arrangement according to the invention Pressure control valve;

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Pig. 4 J in a schematic block diagram a calculator- circuit for a diesel engine which is suitable for controlling the pump provided according to the invention;

I ¹ Xg. 5i shows, in a schematic block diagram, details of a computer circuit which is suitable for use in a gasoline engine and can be used to control the pump provided according to the invention;

Pig 6: in addition to FIG. 5, the remaining parts of an invent improper arrangement for gasoline engines;

Pig »7ί an analog in a schematic block diagram« Calculator that can be used to calculate the size (plus rate of the air volume) »·

In Pig »1 is a diagram of an arrangement according to the invention for diesel engines shown «, the engine 8 has a fuel tank 10 and a fuel feed pump 12, the fuel from the fuel tank through a common fuel feed line 14- pumps. The pump 12 can increase the fuel pressure through the Raise the common feed line to a value that exceeds the maximum pressure required for the injection The common feed line is also known as the "common line". A number of injectors 16, 18, 20, 22, the for example operated by an electrical signal, are for the purpose of fuel injection with the common Line connected on the one hand and the engine cylinders on the other,

The common feed line 14 carries fuel into the fuel tank 10 back via a pressure control valve 24, the details of which in Pig. 5 are shown. The pressure control valve is

by the fuel pressure in the feed line as well operated by an electromechanical actuator - 26 ", which in turn 'can be a coil-operated, magnetostrictive or piezoelectric pump, as in general in Hg o 2 is shown.

An accumulator 28 taps the common feed line with the pressurized fuel in order to serve as an energy source in the vicinity of the injectors and to ensure ^{a good response to the I 1 IuB} generating a voltage whose amplitude is indicative of this pressure "a motorized scanning device 32 includes an arrangement for obtaining electrical ii pulses at a rate determined by the Motorgesehwindigkeit Ireq.uenz. Such arrangements are well known and contain only a motor-driven shaft which actuates a switch at each revolution and thereby generates a voltage signal at the frequency of the motor. The output of the machine-operated device is input to a unit 34 made up of voltage distributors and pulse generator circuitry. The unit 34 contains circuitry for appropriately shaping the waveform of the signal received from the machine-operated scanning device and then applying it to the correct one of the injectors 16-22 distribute _? that is supposed to inject fuel at this time. The duration of the interval over which the injection valves are kept open is controlled by a control element 36 of the operator. The heavier the load, the longer the interval in which the injection valves are open should be. The control element may be the pedal in the operator's cab, which is connected to the unit 34 of high-voltage distributor and pulse generator circuit in order to lengthen or shorten the width of the pulses input to the fuel injectors. Other motor variables used to control the

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The opening times of the fuel injectors that can be used are the engine speed, the · pressure in the Fuel line, engine load, smoke level, air consumption or other parameters. Such data can be provided by appropriate Sensors are converted into signals and used to modify the signals of the control organ * The The circuit arrangement representing this puncture is provided with the reference number 38, Structures for more detailed explanation and Techniques used to modify or control the opening duration of fuel injection pumps are in of FS patent application 33 376 (filed April 30, 1970) "

The output of the machine-operated scanning device 32 is also fed to a tachometer 40, the puncture of which is to generate a signal with a voltage characteristic of the engine speed. The tachometer signal is fed to a circuit 42 which is referred to as a potentiating element. The potentiating element is shown in detail in Pig ", 4" It is used to convert the engine speed into a voltage, the amplitude of which indicates the pressure that the fuel in the common feed line should have at the prevailing engine speed in order to operate correctly of the engine, as it has been described above given. _What if the two voltages characterizing the two pressures are unequal? the comparator 44 gives an output signal to a switch circuit 102. The voltages representing the actual and the desired fuel pressure are additionally fed to a subtraction circuit 98, the output of which represents the inequality between these voltages.

controlled oscillator 100 supplied so that voltage pulses the switch circuit 102 with a frequency proportional to Impose inequality. The output of the switch circuit is input to the electromechanical actuator 26, that, as will be described in the following, the pressure control valve causes the amount of fuel to be increased or decreased from the common feed line in The fuel tank is brought back »This increases the pressure in the common feed line increased or decreased to the value determined for the motor speed.

. 2 shows an electromechanical actuator 26 which can be used in an arrangement according to the invention. It includes a housing 50 which has an electroexpansive element 52 contains. This element can be a stack of piezoelectric disks, a magnetostrictive actuator Coil actuation part or a mechanically operated pump that is actuated by an electrically operated organ or Valve can be associated with an eccentric driver »

The electroexpansive element 52 actuates a piston 54 and causes it to reciprocate in a chamber 56. At one end of the chamber is an inlet to the feed line in which a check valve 58 is inserted ist..In the bottom of the chamber there is an outlet for Pressure control valve 24 »which also contains a check valve 60. ·

It can be seen that the device briefly described above is a pump in which the "fuel" passing through the pump quantity is a function of the operating frequency at a given interval of the electromechanical actuator and the pressure with which the liquid acts on it «one device suitable for the present purposes is in the

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U.S. Patent 3,150,592 (Stec), BR ~ Patent 778,962 (Stevens) or U.S. Patent 3,589,345 (Benson). It should be mentioned that the check valves 58 and 60 are provided to a pressure increase of several 0 "7 M / cm (several Tau send psi).

3 is a sectional view through a pressure regulating valve 24 which can be used in the embodiment according to the invention. It includes a housing 62 having an opening 64 which communicates with a feed line 14. A slidable rod 66 is received in the housing and carries a valve member 68 at one end, which can be moved so that it with the Block or partial opening communicating the feed line can block. The valve member 68 moves in a cavity 70, which is connected to a with the fuel tank Opening 72 communicates. The valve member is biased by a spring 74 which presses the valve member that it closes the opening 64 "

The fuel pressure exerted on the valve member 68 is overcome the pressure of the spring 74 and allows the fuel to penetrate the valve seat and through the opening 72 get back into the fuel tank.

Another chamber 76 is located at that end of the Rod 66 which does not carry the valve member. The other end of this chamber v / eis a pierced pin 78, which is a Represents abutment for a diaphragm spring 80 and the passage of fuel that seeps behind the rod 66, and from Fuel that is pumped by the actuator 26 is restricted but not prevented. The chamber 76 communicates via a passage 82 to the output of the electromechanical actuator 26 ″, the pierced pin 78 is offset by pressure, the diaphragm spring 80 bends and acts as a pressure collector ^ around which the actuating member 26 generates

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generated pulses to smooth and the end of the rod 66 to "apply a uniform pressure".

When the fuel pressure from the feed line 14 is above the Opening 64 is exerted on the valve member 68, it withstands both due to the pressure of the spring 74 and due to the pressure exerted on the end of the rod 66 protruding into the chamber 76, which is produced by the fuel enters the chamber under pressure from the actuator 26 through the passage 82. The counter pressure in the feed line grows until it, acting on the valve member 68, the sum pressure from the pressure on the other end of the rod 66 plus Spring pressure exceeds; this allows fuel to flow more freely from the feed line through chamber 70 and opening 72 flow back into the fuel tank "

4 is a schematic block diagram and indicates the exponentiation element 42, the comparator 44 and the voltage pulse generator 46. The analog voltage at the output of the tachometer 40, which represents the engine speed, is input to a logarithmic circuit 90. It is a well known, commercially available circuit which converts the voltage input to it into a voltage equal to the logarithm of the input voltage. The output of the logarithmic circuit 90 is fed to a multiplier 92 which multiplies the logarithm by η. The factor η can be larger or smaller than 1. The value of η is set beforehand when the engine is tuned and, once fixed, remains constant. The output of the multiplication circuit 92 is applied to an antilog circuit 94. The effect of the operations of the circuits 90, 92 and 94 is to take the voltage indicative of the speed or ÜPM and to raise it to the nth power or to form ^{the quantity (XJPM) 11.} This signal is fed to the voltage comparator 44.

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The other input of the voltage comparator 44 is derived from the pressure transducer 30 and contains a signal which is indicative of the pressure in the supply line. This signal is applied to an amplifier 96 which brings the input signal to a suitable level. The output of the amplifier 96 is applied to the voltage comparator 44 and to a subtraction circuit 98. The other input of the subtraction circuit 98 contains the signal (UPI &) ⁿ _e The difference between the two signals - it is the difference between the actual fuel pressure and the calculated fuel pressure - is fed to a voltage-controlled oscillator 100 * This circuit provides an output signal whose frequency is determined by the The amplitude of the input signal is determined or controlled. «The output of the comparator 44 is fed to a switch circuit 102 which can contain a silicone-controlled rectifier». The silicone-controlled rectifier or holder 102 can be controlled by the output of the comparator 44 in order to pass or block the output signal of the voltage controlled oscillator 100

If the actual fuel pressure is equal to or greater than the calculated fuel pressure (RPM) ²¹ , the comparator sets the switch circuit 102 in a position to pass vibrations of the voltage controlled oscillator 100 to a driver circuit or a voltage pulse generator 46 for the electromechanical actuator. Conversely, if the pressure in the feed line is less than (TJPM) ¹¹ , the voltage comparator in switch 102 allows the oscillations of the voltage controlled oscillator to pass to driver circuit 46 which can then drive the electromechanical actuator. The size of the difference between the fuel pressure of the feed line characterizing the signal and the (UPM) ⁿ representing signal results in the output of the subtraction circuit 98 and to control the frequency of the signal Terwandt _s ^ of the electromechanical for operating

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see actuator serves · So the greater the difference between the actual feed line pressure and the pressure satisfying the relationship p = k (TJPM), the greater the operating frequency of the actuator 26 in the event that Switch 102 is open. With repeated cycles, the actuator increases the fuel pressure between the inlet 64 to the feed line and the outlet 82 to the actuator, so that a total force is exerted on the valve member 68, the it causes the seepage flow from the feed line to the fuel tank to be throttled * Then the pressure in the feed line rises and leads to a corresponding increase in pressure in the chamber 76 because the actuator 26 increases the pressure with a constant increase, and thereby supplies a greater sealing pressure on the valve member 68. If the pressure in · line 14 has the desired relationship with engine speed reached, the comparator 44. closes the switch 102 and prevents further operation of the electromechanical actuator. Then a seepage flow can form again in the pressure control valve, which reduces the pressure from line 14, until the cycle is repeated. The rod 66 cooperates the pierced pin 78 and the diaphragm spring 80 together to that the pulsation generated by the output of the actuator 26 is dampened and provides in cooperation with the adjustable drainage mouth in the membrane 78 a regulator for the hysteresis and the resulting instability of the system.

If the pressure in the feed line 14 increases beyond the desired relationship, for example as a result of a drop in the UPM, which in turn may arise, for example, from a sudden load, the actuating member · 26 remains inactive and the pressure regulating valve member 68 opens as the pressure in the chamber 76 drops; the chamber pressure decreases because the fuel through the control orifice in the pierced pin 78 and on seepage paths on the outer wall of the pin 78

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seeps away. The valve member 68 then moves and opens the mouth 64 even wider; this causes the pressure in the feed line to drop until the desired pressure is restored is whereupon the actuator 26 again worked to maintain this condition

A timing control of when the fuel injectors are 16, 18, 20 and 22 open for a diesel engine is obtained with a system such as that described in US Pat. No. 3,575,146. The regulation of the closing times the valves are monitored by the operator who determines the load requirements a limit for the maximum amount of fuel is desired, to prevent the engine from generating excessive smoke «Since each speed defines its own injection pressure, write the limits for maximum fuel a program for the maximum opening time of the valve as a function of the speed before »So can a control mechanism like him for example described in U.S. Patent 3,575,146 is suitable Way to include a smoke control program. Similarly, cruise control can be incorporated; both Take precautions "the tax given by the operator" signal for the opening period ineffective.

In an Otto engine with internal combustion, the opening time of the fuel injection valves is controlled as a function of operating parameters of the engine, preferably as a function of the amount of air consumed at constant pressure in the feed line. If the pressure in the feed line is not constant, a system must be used, for example as described in our own patent application 155 220 (Oormac G «O'Ueill) entitled" Arrangement for fuel injection and control "(" Fuel Injection and Control. " System ") is described. This application describes an arrangement in which the actual pressure drop across the injectors is registered and that

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Signal is compared with a signal that generates the amount of air flow in the engine. If these signals have a predetermined relationship to one another, for example P _k changes as (air flow), fuel is fed into the engine over a constant angle of rotation of the crankshaft and a constant fuel / air ratio is maintained. If the fuel pressure deviates from the desired relationship, a circuit calculates the injection duration required for the fuel supply required for this pressure and accordingly sets the Y angle of the crankshaft over which injection is permitted to achieve this duration. In such a device an arrangement as described in Pig. 5 can be used to control the actuator.

Pig. 5 is a schematic block diagram of an apparatus for use in accordance with the invention in an internal combustion ignition engine. An air pressure transducer 104 generates a signal Pp which characterizes the pressure at the neck of a so-called yenturimeter 106 through which the air flows into the internal combustion engine. This signal is sent _{to a computer 109 together with signals P 1} and T ₁ , which are each formed by a pressure transducer 105 for the ambient air and a temperature transducer 107 for the ambient air, which calculates the variable (corrected air flow rate) from these signals calculated. In the own patent application 33 376 (Oormac G. O'Neill) with the title "Arrangement for fuel injection with measured quantity flow"("Mass Plow Metered Fuel Injection System") the formula for the air flow through a Venturi tube, the ambient temperature and -pressure takes into account the following equation for the flow rate Y / the amount of air:

= Cd

0 * 286-0.

(D

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with Cdv = coefficient for the outflow from the venturi tube

W - = flow rate

Ay. = Area of the Yenturi neck (6 ^ 45 cm or «, in)

g = 980 cm / sec / sec (dimension factor; 32.2 ft / sec / sec)

P ₁ = ambient pressure

T ₁ = ambient temperature

Pp = pressure at the venturi neck

R = 28.4 m.U / H (gas constant; 96.5 ft «Lbs / lb)

It - factor of a ^l! ^ —Gesetz- * Gases% adopted as 1.4

^P 0 = ^P 1- ^P 2

The ROM 109 computer generated signal representing the square of the corrected luftmengenflußrate "This signal 40 is fed to a circuit which is similar to that described in Fig. 4. It includes a logarithmic circuit 90 'whose output is supplied to a circuit 92 supplied η for multiplication by the factor _s whose output in turn is applied to a antilog circuit 94 _e In this circuit is charged on the input signal to the n-th power ^ wherein the factor η between Oj5 and are 2,5 can _e the output of the antilog circuit 94, which represents the size (corrected Luf tmengenf lußrate) ^11, is supplied to the voltage comparator 44 and to a subtracting circuit 98th The respective other input of the voltage comparator and the subtraction circuit 98 is derived from the output of an amplifier, whose input wirdj subjected to a pressure drop of the fuel via the fuel injection valves performing voltage is obtained as shown in Figure _# 6 in turn of a transformer 111.

When the amplified fuel pressure drop signal from amplifier 134 exceeds the calculated fuel pressure, controls the voltage comparator 44 the Sehalter circuit 102, so that no output signal Tom oscillator 100 to the electromechanical Driver circuit 46. «If the force—

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substance pressure signal falls below the air flow signal, brings the comparator 44, the switch circuit 102, signals from the voltage-controlled oscillator 100 to the driver circuit for the electromechanical actuator to pass through. The subtraction circuit 98 forms a voltage which the Difference between the two entered into the voltage comparator Represents voltages and the difference is used to control the voltage controlled oscillator 100. The frequency of the voltage-controlled oscillator is characteristic of the size of the input signal »,

By setting the exponent η, phenomena of the air and hydraulic flow can be taken into account modify the Bernoulli relation p ^ v of incompressible media, regardless of whether these modifications result from fuel or air effects. Such an effect can for example through violent pulsation in the intake system when using ram pipes or resonance chambers be generated. In such cases the air flow forms a mean signal of greater value than it is the square Supplies mean value (rms value) of the instantaneous current characteristic.

It will be appreciated that such a device can maintain the air flow rate and fuel pressure in the desired manner at all times Relationship lasts. However, the required pressure range can be between maximum fuel flow and maximum speed and minimum fuel flow at minimum speed to achieve a constant crankshaft angle injection period between 1000 and 1500: 1. I * ure an acceptable one For fuel pump life, the maximum injection pressure should be limited to 276 ϊΓ / cm (400 psi) or less be, and consequently the fuel pressure, the in the common line when the engine output is low, there is steam inclusions due to the absorption of the engine housing

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Heat "form. These inclusions are cause undesirable and Wunen measurement error or run unevenly ·

To avoid this problem, the fuel pressure in the line is not allowed to drop below a level empirically determined to prevent vapor formation is. The minimum pressure can be achieved by giving the spring 74 (Pig «3) a greater strength so that in the Pressure line of the igniter engine with internal combustion a minimum pressure of sufficient size before the pressure control valve can open «

Fig. 6 shows very schematically, the inventively provided apparatus for the in Pig x 5 illustrated required in a detonator An internal combustion engine is additionally · A fuel tank 110 supplies fuel to a pump 112, this fuel into a common line 114a, 114b feeds, which branches off to feed fuel injection valves 116 to 125. The branched fuel line is then brought together again and returns to a pressure regulating valve 124 as a single line. The fuel return line is additionally connected to an electromechanical actuator 126. The structure and mode of operation of the electromechanical actuator and the pressure regulating valve are the same as those described in connection with FIG. 1 _and their description is therefore omitted here

The pressure transducer 111 could be constructed in such a way that it controls the pressure difference between the fuel pressure in the feed line 114a, 114b and the pressure in the intake manifold 128 of the motor detected The signal from the pressure transducer 111 can therefore used to regulate the fuel pressure,

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and also serve to determine the duration of the fuel injection in a control system as described in our own US patent application 155 220 (Cormac O'Neill) entitled "Arrangement for Fuel Injection and Control" ("Fuel Injection and Control System ") is described to calculate ·

In diesel engines that have an injection system with a common line and timed injection valves, allows the regulation of the fuel pressure in a constant Relation to the speed that the injection rate of the fuel is set in addition to the injection duration " As a result, the engine can operate more smoothly and quietly with less stress (increased service life) at low load factors.

The wear and tear of the pump for the fuel pressure can be on a Minimum can be reduced by keeping their operation at peak injection pressure only asks for the time when such pressure is actually necessary. Require known orders that this pump at all times at peak supply pressure: works, they not only affect the service life, but also cause fuel heating, Fuel aeration and power dissipation with one of them resulting high specific consumption at low load,

In gasoline engines which have a fuel injection system with a common line and injectors for each port or cylinder, a fixed link between engine speed and pressure in the fuel line of the type ρ = Ku / ¹ can be obtained; where ρ is the fuel pressure, W-the RPM of the engine, K is a constant and a is the exponent, which can easily be changed for tuning purposes. The pressure relationship can be precisely maintained with a system that is free from mechanical complexity and not dizzy-

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te

“Known systems with constant pressure in the fuel line are not able to receive a maximum of fuel, which per stroke within the effective opening process of the intake valve is injected, and a minimum valve opening duration with the power of injection pumps ^ which according to present State of the art ",

7 is a schematic block diagram of an analog computer 109 suitable for determining the quantity which is input to the logarithmic circuit 90 in! "Ig x 5. Looking at equation (1) it can be seen that the quantity _ηΛ . V 2 ^ _e g * equal to a calculable constant

K is because for any given venturi all values are this Terms are constant «The remaining part of equation (1) can be rearranged to simplify mechanization, so that the entire equation can be

The signals P _Q, P ₁ and T. are all amplified and get their sign reversal by the ^ © weiligen amplifier 130 and _$ 134 each -pq> -P ₁ and T ₁ form. -Pq and -P ₁ are input to attenuators 136 and 137 to form -O, 3O6P _Q and -0.286P _1. These values are then fed to a two-input amplifier 140 which has the sum '- (- 0.286B ₁ + 0.306Eq) forms * The output of this amplifier is fed to an amplifier 142 whose gain

is chosen so that it multiplies the output signal with K to form the product K ² (0 « 286P ₁ + 0.306P ₀ ) *

The signal -S ₁ is input as an input to a multiplier 139 «, which is in the negative feedback loop

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an amplifier 138 is located. The second input signal of the multiplier 139 is the negative feedback of the amplifier, As a result, the output of amplifier 138 is Pq / I.j. This quantity is then combined with the output of the Amplifier 142 to multiplier 144 to form the output

input W entered. This exit will be seen by the loga-rithmi Circuit 90 in Fig. 5 supplied "

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Claims (1)

Patent claims β Arrangement for fuel injection in an internal combustion engine with a fuel injection valve for each cylinder and a common feed line for feeding fuel into the fuel injection valve, thereby. characterized in that a first and a second converter circuit are provided for changing the fuel pressure according to a freely predetermined parameter of the engine, the first converter circuit (28, 30) being one of the fuel pressure in the common feed line (14; 114a, 114b) dependent voltage (first voltage) and the second converter circuit (32, 40) generates a voltage (second voltage) that is dependent on the freely specified motor parameters, so that a powering circuit (42) raises the second voltage to the nth power, where η is a adjustable Paktor, the value of which is determined by a freely predetermined engine tuning, and forms a voltage (third voltage) which represents a desired fuel pressure that a comparator circuit (44) compares the first and third voltage with each other and the greater of the two as well their difference is determined and that the arrangement contains a controller (24, 26, 46, 124) which is dependent on the output signal of the comparator circuit (44) the fuel pressure in the common feed line (14; 114a, 114b) changes at a rate determined by the difference until the fuel pressure assumes the value _{β determined by the third voltage} 2. Arrangement according to claim 1, characterized in that the second converter circuit (32, 40) - 22 50 9647/001 1 a tachometer (40) for determining the engine speed representing tension contains " 3. Arrangement according to claim 1, characterized in that g e k e η η that the second converter circuit (32, 40) has a converter (104, 105, 107, 109) for generating a Contains voltage which represents the pressure differential of the amount of air supplied to the engine through a venturi (106) flows, 4 «Arrangement according to one of claims 1 to 3, characterized in that the controller (24, 26, 46, 124) comprises an electromechanical pump (actuating member 26) which is used to increase the fuel pressure with fuel from the fuel line (14 ?, 114a , 114b), and a control valve (J pressure control valve 24, 124) which is charged with the higher pressure fuel from the outlet of the electromechanical pump (26) and controls the rate at which fuel in the common feed line (141, 114a, 114b ) can circulate, making its pressure controllable _e 5. Arrangement according to one of claims 1 to 4, characterized in that in an internal combustion engine, in which the fuel by a pump (26) from the common feed line (14; 114a, 114b) into a Fuel tank (1O, 110) and from there in a pump (12) in Circulation is set, which pumps the fuel into the common feed line (14; 114a, 114b) that is generated second voltage represents the speed of the motor that the comparator circuit (44) has a first output signal generates when the first voltage exceeds the third voltage and generates a second output when - 23 509847/0 011 the third voltage exceeds the first and that a control valve (24-124) connects the common feed line (14; 114a, 114b) connects to the fuel tank (10; 110), the fuel flow in response to the first output signal increases, thereby reducing the fuel pressure, and in response to the second output signal, decreases fuel flow, thereby increasing fuel pressure. Arrangement according to claim 5, characterized ge ke η η - is characterized in that a subtracting circuit (98) is provided, which subtracts the first voltage from the third voltage to form a difference voltage that is a voltage controlled oscillator (100) generates a pulse train whose frequency by the differential voltage is determined so that a gate (switch circuit 102) remains closed to the first output signal and opens to the second output signal and allows the pulse train from the voltage-controlled oscillator (100) to pass and that an electromechanical actuator (26; 126) β is connected to the gate (102) for controlling the control valve (24; 124) as a function of the pulse train Arrangement according to Claim 5, characterized in that in an internal combustion engine in which the fuel is circulated by a pump (26; 126) from the common feed line into a fuel tank (10; 110) and from there to a pump (12) , which pumps the fuel into the common feed line (141 11 4- & _s 114b) that the first voltage represents the fuel st off pressure across a fuel injection _{valve (16, 18 f} 20 _s 221 116-123) that the second voltage the M-ußrate of the amount of air in the engine represents that the comparator circuit (44) generates a first output signal - 24 509847/0011 testifies when the first voltage exceeds the third voltage and generates a second output signal, when the third voltage exceeds the first, and that a control valve (26; 126) die'common feed line (14; 114a, 114b) connects to the fuel tank (10; 110), namely, increases fuel flow in response to the first output signal, thereby decreasing fuel pressure is, and in response to the second output signal decreases the fuel flow, whereby the fuel pressure increases· 8. Arrangement according to claim 7> characterized in that it has a subtraction circuit (98) which subtracts the first voltage from the third voltage to form a differential voltage, that a voltage-controlled oscillator (100) generates a pulse train, the frequency of which is determined by the differential voltage it is determined that a gate (switch circuit 102) is closed in response to the first output voltage stays and. opens on the second output voltage and the pulse train from the voltage controlled oscillator (100) lets through and that an electromechanical actuating member (26; 126) with the gate (102) for controlling the control valve (24; 124) as a function of the pulse sequence connected is. - 25 509847/0011 Blank page