DE2316814A1 - FUEL SUPPLY SYSTEM FOR ONE ENGINE - Google Patents

Description

PATt NT ANWÄLTE DipL-Ing. WERNER COHAUSZ Dipl.-Ing. WILHELM FLORACK . Dipl.-Ing. RUDOLF KNAUF

4 Düsseldorf, Schumannstrasse 97 2316814

C.A.T. Limited

Well Street

GB-Birmingham 2nd April 1973

Fuel supply system for an engine

The invention relates to a fuel supply system for a Engine.

A fuel supply system according to the invention is characterized by a pump for supplying fuel to the engine, an actuator for controlling the output of the pump, a control circuit, receives the signals which reflect at least two operating variables of the engine, one of which is from another is derived which measures the engine speed, the control circuitry controls the actuator, and a supply of fuel to the Engine inhibiting means except when an output is generated by the converter.

In a preferred manner, the means have a safety circuit which prevents fuel from being fed to the engine, the Converter is set up to block the safety circuit when an output is generated.

In a preferred manner, the converter generates an AC signal at a frequency that reflects the engine speed, with the signal passing through a pump circuit to provide the necessary blocking of the safety circuit goes. The same pump circuit can do the required Provide input to the control circuit, or a second pump circuit coupled to the converter can be used for this Purpose to be provided.

Gate trains, the system has means for limiting the engine speed and a control network that can be activated when the 27 140

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exceeded the maximum engine speed for some reason. will, such that the supply of fuel to the engine is cut off will.

On the other hand, the invention consists in a fuel supply system for an engine, which is characterized by a pump for supplying fuel to the engine, an actuator for control the output of the pump, an electronic regulator for control of the actuator, wherein the glider contains means which are set up to limit the maximum engine speed, and a control network, which can then be actuated if for any reason the maximum engine speed is exceeded, in such a way that the supply line fuel to the engine is prevented.

The control network preferably receives a from a converter substantially linear output which changes with engine speed, and the control network comprises a transistor whose Control electrode (or emission electrode) is held at a fixed voltage and its emission electrode (or control electrode) is connected to the output from the converter in such a way that the transistor conducts when the output from the converter reaches a setpoint value, wherein the collector current of the transistor is used to cut off the supply of fuel.

The invention is explained in more detail below with reference to the drawings. In the drawings are:

1 is a circuit diagram, partly in block form, showing an embodiment of the invention as applied to a diesel engine shows that is set up to drive a motor vehicle

is,

FIGS. 2 to 4 are graphs showing the outputs at various Points in the circuit diagram shown in Fig. 1 show

Fig. 5 shows one form of control circuit for use in the in Fig. 1 shown arrangement,

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6 shows the characteristics of the engine according to Pig. 1 and Pig. 7 one of the pig. 1 corresponding representation in which another Embodiment is shown.

According to Pig. 1, a pump 11 is provided which feeds fuel to an engine 12. The speed of the engine is determined by a converter 15 measured, which has an AC output with a frequency generated which is proportional to the engine speed, and this output is fed to a diode pump circuit 14 which has an output in the in Pig. 2 generated. This output is fed to a control circuit 15 which also has inputs in the in Pig. 3 and 4 from a transducer 20 receiving the Pump output measures, also from a converter 16, the fuel requirement and is controlled in a vehicle by the accelerator pedal. The control circuit compares the signals it receives, and it produces an output which is fed through a power amplifier 17 to an electromechanical actuator 18, the A control rod 19 serves to close the output of the pump 11 determine. As shown in Fig. 1, the pump output is conveniently measured by the position of the control rod 19 is determined. The actuator 18 can be servo-assisted. In In this case it only controls a valve which in turn controls a hydraulic circuit for actuating the rod 19. In both In cases, the rod 19 is preferably tensioned by spring force in a position in which the fuel supply is cut off, so that the actuator is fail-safe.

The system has a positive and a negative energy line 21, 41 and a power line 22, which is based on a voltage in the middle between the voltages of the lines 21, 41 held will. All power lines are derived from the vehicle battery. The zero point in Figures 2-4 is the line voltage The output from transducer 13 is connected to line 22 through a series connection to which a resistor 23, a capacitor and a diode 25 belong. The connection between the capacitor

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24 and the diode 25 is connected to the line 22 via a mode 26 and a resistor 27 connected in series, whereby the resistor 27 a capacitor 28 is connected in parallel.

The connection between the diode 26. and the resistor 27 is further connected to the control electrode of a p-n-p transistor 31, its emission electrode with the line 21 via a diode 32 and a resistor 3 are connected in series. The connection between the resistor 33 and the diode 32 is connected to the line 22 through a diode 54, a diode 35 and a resistor 36 in Series connected, and the connection between the diode 35 and the Resistor 36 is connected to line 21 via a resistor 37. The collector of transistor S3I is with a controller 38 connected, which provides an input for the control circuit 15. The control circuit also receives an input from one Control 40, which determines the maximum speed of the motor.

When the circuit is switched on for the first time, then flows when converter I3 is not producing an output, power from the line 21 through the emitter / control electrode path of the transistor 31 and the resistor 27 »to turn on the transistor 31, the provides an input via the controller 38 for the control circuit 15, which prevents fuel from being fed to the engine. However, when the converter 13 produces an output, the diode pump circuit produces which is formed by the capacitors 24 »28 and their associated Sauteile, an output at the capacitor 28, the sufficient to turn off the transistor 31, so that the safety circuit formed by the transistor 31 and its associated components is blocked and the control circuit 15 the electromechanical Actuator 18 can operate so that a supply of fuel to the engine 12 takes place.

It is understood that due to the fact that the output of of the diode pump circuit Η shown in Fig. 2 has a large one Area, this output is preferably not used for this purpose

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is to control the transistor 31. The voltage across the capacitor 28 increases with engine speed, and it will be understood that, "since the arrangement is primarily intended, with failure of the transducer 13, the arrangement may be one must that only a low output voltage on capacitor 28 is required is to turn the transistor 31 off. Of course, transistor 31 must be off when the engine has started will.

In a variation, the output from transistor 31 actuates one Control which acts on the booster 17 so that the booster cuts off the supply of fuel. In this case the transistor 31 can act directly on the amplifier 17 without the control 38

The role of the diodes 34t 35 is their associated resistor network consists in setting different threshold voltages and for temperature compensation for the diode 32 which protects the emission electrode / control electrode path of the transistor 31, and also the control electrode and the emission electrode of transistor 31 *

It goes without saying that if at any point in time the converter 13 fails or any other fault occurs, that no output signal comes from the converter 13, the transistor 31 conducts, so that the control network 38 is put into operation, to cut off the supply of fuel.

As mentioned above, stell; the controller 40 the maximum speed of the engine. However, if for any reason, for example if the controller 40 »fails, the maximum engine speed increases increases a value beyond the safety value set by the controller 40, steps must be taken to to ensure that no damage occurs. For this reason, two resistors 42, 45 are provided in series between the

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Lines 21, 41 are connected. The connection between the Resistors 42, 43 is connected to the control electrode of an n-p-n transistor 44, the emission electrode of which is connected to the output terminal of the pump circuit 14. The collector of the transistor 44 actuates a safety network 45, which in the switched-on state on the amplifier 17 or the circuit 15 acts to limit or prevent the supply of fuel to the engine. When the transistor 51 is on the amplifier 17 is to take effect, he can do so through the safety network 45.

You control electrode voltage of transistor 44 is set to one Set the value between the voltages of lines 21,, 41 lies. If one realizes that the zero point in Fig. 2 is the voltage on line 22, it can be seen that the emissive electrode voltage of transistor 44 is always above the voltage of Line 22 is located. As the engine speed increases, the voltage at the emission electrode of transistor 44 decreases, however in normal operation of the system the transistor never turns on. However, if the controller 40 fails, the engine speed will decrease to, and the voltage at the output of the pump circuit 14 decreases to such a value that the transistor 44 conducts and one Input to the safety network 45 supplies so that the fuel supply line is limited or prevented.

In order to ensure maximum security, the arrangement is with small Modifications provided twice. The output connection of the circuit 14 is connected to the line 22 via resistors 84, 85 connected in series, with the connection between the resistors 84, 85 connected to the control electrode of a p-n-p transistor 86 is, whose emission electrode is connected to the line 22 and whose collector is connected to a safety network 46, which is shown in corresponding to how the network 45 functions. The transistor 86 conducts simultaneously with the transistor 44

In Fig. 5 there is shown one form of control circuit 15 which is shown in FIG

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Pig. 1 is included. The control circuit has two function amplifiers 51 »52, the output connections of which via diodes 53 or 54 are connected to the amplifier 17. Each of the amplifiers 51 »52 is connected between the lines 21, 41, and the non-inverting inputs of amplifiers 51 »52 are connected to the Line 22 connected. The amplifiers are connected to act as summing amplifiers, and are for that purpose Resistors 55 »56 between the input of amplifier 17 and the inverting inputs of the amplifiers 51 »52 are switched. The reason the feedback resistors 55, 56 are coupled to the input of amplifier 17 is that the temperature Characteristics of the diodes 53 »54 have no significant influence have on the function of the circuit.

The pump circuit 14 is connected to the inverting input of the amplifier 51 coupled via a resistor 57. The converter 16 is coupled to the inverting input of amplifier 51 via a resistor 58. The output from converter 20 is through resistance 59 »61 coupled to the inverting inputs of amplifiers 51 and 52, respectively. Furthermore, two power sources 62, 63 are provided, those with the inverting inputs of amplifiers 451 or 52 are coupled for a reason to be described. The controller 40 is coupled to the converter 15 and limits the maximum speed A by limiting the fuel requirement.

How the Pig. The arrangement shown in FIG. 5 can best be described with reference to FIG. If for the moment the amplifier 52 is disregarded, the compares Amplifier 51 the Staa flowing through the resistors 59 and 57 with the current flowing through the resistor 53 and generates a Output to amplifier 17 »which modifies the fuel flow, to provide the required engine characteristics. Line 71 in Figure 6 is one of a family of lines representing the target engine speed represent. So when the pedal is in such a position that the setpoint is represented by line 7I, the engine works at a point on the line 7I passing through the

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Load on the motor is determined. The lowest engine speed is at 72 and is determined by source 62, The Control 40 defines the line 74 for the maximum speed

The object of the amplifier 52 is to limit the maximum pump output to a desired value, w _a s in ¥ ig _B is represented by the line 75. 6 When the pump output reaches a set point determined by the source 63, the amplifier 52 produces an output higher positive than the amplifier 51, the diode 53 is reverse biased and the amplifier 52 controls the pump output. The circuit is arranged so that a decreasing output from an amplifier 51, 52 reflects a need for an increase in fuel delivery. ■.

The boundary line 75 "which is shown in dashed lines in Jig * 6 _P is a function of the engine, not of the glider, and it represents the fuel requirements of the engine in the no-load condition under various demand values.

It goes without saying that in 3? Ig. 6 explains how the engine behaves under any circumstances. Assume ₉ the pedal has been set to a fuel requirement which is represented by the line 71. _S mentioned above depend on the precise location on the line 71 i * ¹ any particular moment of the load on the engine. Thus, when the vehicle begins to climb an incline, the load increases, and when the pedal is not moved the operating point moves up along line 71. If the load becomes sufficiently large, line 73 is reached and none further increase in pump output wM permitted At this point the speed drops rapidly. When the load decreases, the operating point moves along the line 7I downwards ₅ accompanied by a corresponding increase in the speed _o liJexui the load drops to UuIl, the line 75 is reached «,

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If the "Shafts toff requirement is changed, under the assumption, that a maximum fuel requirement is required, the pump output as fast as the pump and the bowler allow, until the line 73 is reached, and the operating point the motor then travels along line 73 to a point on line 74 which is determined by the load. Benn the fuel requirement is decreased, for example to zero, the pump output decreases as quickly as the pump and controller allow, From until the fuel line is Hull. The speed then decreases until line 72 is reached and the operating point remains on line 72 at a location determined by the load.

Also shown in FIG. 5 is the controller 38 used in FIG. 1 when the control circuit 15 has the form shown in FIG. The collector of transistor J1 is connected to line 41 connected through a resistor 81, and it is also connected to the control electrode of an n-p-n transistor 82, its emission electrode with the line 41 and its collector with the inverting The input of the amplifier 51 is connected via a resistor 64 are. Such an arrangement is provided that when switched on Transistor 31 the transistor 82 is turned on and modifies the current flowing to the inverting input of amplifier 51 to provide the required control.

It is of course understood that the control circuit in various Shapes can be provided. In another embodiment, the converter 16 requires a certain amount of fuel, and not a certain speed. In such an arrangement, the line 71 lies horizontally in FIG. 6. The circuit according to FIG such an arrangement can be used with appropriate modifications. The pump circuit 14 provides an input to the amplifier 52, but not to amplifier 51 · The input to amplifier 52 from the Pump circuit 14 enables amplifier 52 to set the maximum speed. It will be understood that the slope of the line 74

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is reached due to the input to amplifier 52 via resistor 61. The amplifier 51 now compares the target fuel with the actual fuel and generates the required horizontal line which replaced the line 71 in FIG. 6. The control §40 still limits the maximum fuel requirement ₉ but now generates the line 73 'and the control 62 generates the line 72. However, if the line ^ 2 has a slope, the control 62 now requires a speed value

The operation of the arrangement shown in Pigo 1 is not affected by these changes in the control circuit, and in particular 82 acts the transistor is still on the amplifier 51 via the resistor 64 a _e

As shown, .An arrangement shown in Figo 1 does not check for a failure of the circuit 14 'and, optionally, means may be provided to cause ein® control & Bg when the circuit 14 is auefällte ZweekmäßigeEweis © the characterized erreieht ₉ that Desie output voltage of the circuit 14 is compared with the voltage on the capacitor 28. The comparator used for this purpose then detects a failure of the circuit I4 _o

In FIG. 7 gezeigte'Aasführungsbeispiel represents a modification of the arrangement shown in FIG. 1. In FIG _{o o} 7, the Leittm- gen 21, 22 by two resistors 87, 88 connected to each other in Eeihe, wherein the junction between the resistors 8JS 88 is connected to the control electrode of an np ° n transistor 89, the collector of which is connected to line 21 via a resistor 91. A further NPN transistor 92 is provided and the emission electrodes of the transistors 89, 92 are connected to the line 22 via a resistor 93. The transistor 92 has its collector connected to the line 21 via a resistor 94, and its control electrode is -he connected to the output of the pump circuit I4 via a resistor -95.

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trode tizw. connected to the emission electrode of a p-n-p transistor 98, its collector is connected to the safety network 46 is.

The transistors 89 »92 act as a long-tailed pair (longtailed pair), the transistor 92 receiving an input that is linked to the engine speed decreases (Fig. 2). At speed NuIl the transistor 92 is switched on, the transistor 89 is switched off, so that transistor 98 is turned on to provide network 46 to actuate. As the speed increases, the transistor 92 conducts less and the transistor 89 conducts correspondingly more, until the transistors 89, 92 conduct the same at a target speed and the Transistor 98 is turned off.

Patent claims

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Claims (18)

Claims 2 -5 IDOI 4 (I5J fuel supply system for an engine, characterized by a pump for supplying fuel to the engine _9, an actuator for controlling the output of the pump, a control circuit which receives signals which reflect at least two operating variables of the engine, one of which is derived from a converter, which measures the engine speed, the control circuitry controlling the actuator, and a supply of fuel to the engine except when an output is generated by the converter inhibiting means. 2. System according to claim 1, characterized in that the means have a safety circuit which prevents the supply of fuel to the engine, the converter being designed to block the safety circuit when an output is generated. 3. System according to claim 2, characterized in that the converter generates an AC signal at a frequency representative of engine speed, the signal being passed through a pump circuit to provide the necessary blocking of the safety circuit. 4 · System according to claim 3 »characterized in that the security s circuit has a transistor which is biased to conduct, but is turned off by the output of the pump circuit. 5 · System according to claim 3 »characterized ₉ that the safety sschaltung comprises two transistors which are connected as a long-tail pair (long-tailed pair), wherein a transistor is connected to its control electrode connected to the output of the pump circuit and a third transistor having the Transistors in the transistor pair is coupled so that it is switched off at a target engine speed. -_ ■ 6. System according to claim 3 or 5 »characterized in that the Pump circuit also for the required input to the control switch Wa / Ti. _ 2 - 3G9842 / 0477 tion ensures. 7 »System according to claim 3 or 4t characterized in that one another pump circuit coupled to the converter for the required input to the control circuit. 8. System according to claim 7 »characterized by means for checking the puncture of the first pump circuit and for taking a controller if the first pump circuit fails. 9 * Seka system according to claim 8, characterized in that the first Pump circuit is checked that its output voltage is compared with the output voltage of the second pump circuit. 10. System according to one of claims 1 to 9 »characterized by Means for limiting the engine speed and a control attachment which is then actuatable when the maximum engine speed from any Reason is exceeded in such a way that the supply of fuel to the engine is cut off. 11. System according to claim 10, characterized in that the control network has at least two independently operating arrangements, each of which blocks the supply of fuel to the engine, if the maximum speed of the motor is exceeded, 12. System according to one of claims 1 to 11, characterized in that that the control circuit receives, in addition to the engine speed signal, signals indicating the fuel requirement and the pump output reproduce, and compares the three signals so that an output a for controlling the actuator is provided. 13. System according to claim 12, characterized in that the control circuit a first summing amplifier which receives input signals which the engine speed, the fuel consumption and the Play the pump output, and an output to control the - 5 309842/0 ^ 77 Actuator supplies, and a zxfei th summing amplifier travels, which an input signal <> which reproduces the pump output ₉ and receives a reference, this second amplifier overriding the first amplifier to limit the pump output _{or the like} 14. System according to claim 12, characterized in that the control circuit _{receives a first summing amplifier © r s of} the signals which reflect the pump _{output and the fuel requirement f} and an output for controlling the actuator supplies ₉ and a second summing amplifier having a Signal representing the engine speed and receiving a reference and the first summing amplifier to limit "the engine speed overriding." 15 «fuel supply system for an engine ₉ characterized by a pump for supplying τοπ fuel to the engine, an actuator to control the output of the Pampe, an electronic glider to control the actuator, the Hegler means eat · = keeps that to limit the maximum engine speed are set, and a control network · _s which is then actuated when the maximum engine speed is exceeded for any reason., such that the supply line is inhibited of fuel to the engine, 16. System according to claim 15s, characterized in ₉ that the control network receives a substantially linear output from a ¥ andler which changes with the engine speed, and has a transistor whose control electrode (or emission electrode) is kept at a fixed voltage and its emission electrode (or control electrode) is connected to the output from the converter _{t in} such a way that the transistor conducts when the output from the converter reaches a setpoint value, the collector current from the transistor being used to cut off the supply of fuel « 17 · Syytem according to claim 15 or 16 _S, characterized in that the sailor assigns a first summing amplifier ^ to the · signals. - 4 309842/0471 ■ "■" ■ 23168 U that the engine speed, the pump output and the Reproduce fuel demand, the first summing amplifier providing an output for actuating the actuator, and a second summing "amplifier, which a signal, representing the pump output and receiving a reference, wherein the second amplifier is the first amplifier for limiting the pump output overridden, wherein the means for limiting the maximum engine speed come into puncture that the input to first summing amplifier is modified. 18. System according to. Claim 15 or 16, characterized in that the controller has a first summing amplifier that receives input signals representing the pump output and fuel demand, and provides an output for actuating the actuator, and having a second summing versa, the means to limit the maximum engine speed and a signal » which reproduces the Hotordreahzahl, and receives a reference and overrides the first summing amplifier to limit the engine speed. 19 · Fuel supply system for an engine, marked arrangement by a pump for supplying fuel to the engine, an actuator for controlling the output of the pump, a converter for generating an output voltage dependent on the engine speed, an electronic controller that receives input signals, which the engine speed, the pump output and the fuel consumption reproduce, and the actuator controls, and safety means for preventing the supply of fuel to the engine always when the output from the converter arrangement indicates that the engine speed is either below a first value which is less than is the starting speed of the motor, or is above a second value that is greater than the normal maximum speed of the motor. 309842/0477 Blank