GB2104157A

GB2104157A - A method of and an arrangement for determining injected quantities of fuel

Info

Publication number: GB2104157A
Application number: GB08220750A
Authority: GB
Inventors: Eckehart Schmitz; Hans Baumgartner; Rainer Sudbeck
Original assignee: Pierburg GmbH
Current assignee: Pierburg GmbH
Priority date: 1981-07-17
Filing date: 1982-07-16
Publication date: 1983-03-02
Also published as: DE3128238C2; IT8248813A0; IT1148356B; GB2104157B; FR2509855B1; FR2509855A1; DE3128238A1

Abstract

In a method and an arrangement for determining the quantity of fuel injected by means of a camshaft- driven piston injection pump for automatic-ignition internal combustion engines, the pressure pulses occurring in the output pressure line of the injection pump during the injection-effective delivery stroke are directly or indirectly determined in respect of their pulse duration and their pulse intervals. A certain injection stroke or a certain quantity of fuel injected per work cycle may be associated in pump-specific form with each pair of these values and stored and retrieved as required. This cycle-related injected quantity may be used for determining the consumption of fuel per unit time or per unit distance travelled and optionally averaged out as a function of time or even the overall consumption, optionally with the assistance of other values, such as the rotational speed as derived from the pulse intervals or a speed signal.

Description

SPECIFICATION A method of and an arrangement for determining injected quantities of fuel This invention relates to a method of and an arrangement for determining the quantity of fuel injected by means of a camshaft-driven piston injection pump in an automatic-ignition internal combustion engine.

For determining quantities of fuel injected, i.e.

fuel consumption, it is possible in principle to measure the throughflow volume. However, this is both unfavourable and inaccurate, particularly in the case of diesel injection systems, because two throughflow measurements have to be carried out for the input quantity and the return quantity and the difference between them subsequently formed. Since the return quantities are particularly large in the case of diesel systems, this measuring technique gives relatively inaccurate results.

Camshaft-driven piston injection pumps for automatic-ignition internal combustion engines generally have a constant piston stroke and an effective delivery stroke governed by the particular angular position of the piston. This angular position or rather the delivery stroke is variable by means of a control rod. Depending on the position of the control edge of a pump piston of the injection pump, the beginning or the end of the delivery stroke coincides with a certain position of the driving camshaft, whereas the end or the beginning of the delivery stroke is variable according to the position of the control rod.

Accordingly, it would be possible, in principle, to determine the magnitude of tha particular delivery stroke by modifying the injection pump in such a way that the particular position of the control rod can be determined, for example, by means of a potentiometer.

An object of the present invention is to develop a method and an arrangement in such a way that the quantity of fuel injected per work cycle can be accurately determined by relatively simple measures without any need for modification of the injection pump and irrespective of the principle on which it is controlled and/or functions.

According to the invention there is provided a method for determining the quantity of fuel injected by means of a camshaft-driven piston injection pump in an automatic-ignition internal combustion engine, wherein the injection duration Te and the injection period Tp per work cycle of the injection pump are determined by direct or indirect detection of the pressure pulses of the fuel-pressure trend as a function of time behind the outlet of the injection pump and the particular injection-active pump delivery stroke or the associated injected quantity of fuel per work cycle is determined from the injection duration and the injection period and from their relationship with the pump-specific delivery stroke curve dependent upon the rotation of the camshaft.In the present invention, therefore, use is made of the fact that, during the effective delivery stroke of the injection pump, a pulse-like increase in pressure beyond a suitably selected threshold pressure occurs in the delivery pipe or in the pressure line of the injection pump between the injection pump and the following injection nozzle. During this pressure pulse, the return pipe from the injection nozzle to the fuel tank is shut off and a calibrated orifice of the injection nozzle is opened. The increase in pressure arises out of the fact that the fuel is forced through the calibrated nozzle orifice and is injected into the working space of an internal combustion engine.

Since the pulse or injection duration is to the pulse or injection period as the injection angle between the beginning and the end of the effective delivery stroke is to the total angle of one camshaft revolution of the piston injection pump, the effective delivery volume or rather the quantity of fuel injected per work cycle may be determined from the injection duration and injection period values obtained from the pressure pulses and by means of the delivery stroke curve known for each injection pump and the particular piston area of the pump. Since it is only the pressure states behind the injection pump or quantities derived therefrom that are taken into consideration, the measuring process may be carried out very simply without any need for modification of the injection pump.

The pressure pulses in the output delivery pipe of the injection pump are preferably directly detected. Instead of this, however, it is also possible, in principle, for the pressure pulses to be indirectly detected by determining changes in the diameter and/or length of the output delivery pipe of the injection pump or by determining the opening movements of an injection nozzle following the injection pump and provided with a closing member biassed in the closing direction.

In all these cases, the injection duration and the injection period may be derived sufficiently accurately from the pressure pulses.

Another, preferred embodiment of the invention is characterised in that the injection angle (pe=27tTe /Tp is calculated from the injection duration Te and the injection period Tp, in that injected quantities of fuel associated with a plurality of different predetermined values of the injection angle Pe in accordance with the pumpspecific delivery stroke curve are stored as characteristic quantities and in that the stored injected quantity corresponding to the particular calculated injection angle is determined.Instead of this, however, it is also possible, with advantage, for injected quantities of fuel associated with a plurality of different predetermined values of the injection duration Te and the injection period Tp, in accordance with the pump-specific delivery stroke curve to be stored as characteristic quantities in an identification field and for the stored injected quantity corresponding to the particular values determined for the injection duration Te and the injection period Tp to be determined.Whereas, in the first case, the injection angle is calculated and a linear identification field may be used in respect of the dependence of the quantity of fuel injected upon the injection angle, there is no need in the second method for the injection angle to be calculated and a two-dimensional identification field is used in respect of the dependence of the quantity of fuel injected upon the injection duration and the injection period.

In both cases, the quantity of fuel injected is preferably determined by interpolation between the stored injected quantities. In this way, the size of the identification field to be stored and hence the outlay involved in terms of measuring technology and equipment may be kept within reasonable limits providing the result of the measurement is sufficiently accurate. Apart from the fact that the entire delivery stroke curve could also be suitably stored, the storage of individual, suitable curve points is more practical and less expensive.

By forming the reciprocal value of the period Tp of the pressure pulses, the process according to the present invention makes it possible very easily to determine the rotational speed n of the injection pump camshaft and hence of the internal combustion engine by which it is driven without any special measures having to be taken to that end.

Another preferred embodiment of the invention is characterised in that the quantity of fuel injected per unit of time is determined by forming the product between the quantity injected per work cycle and the rotational speed n or the reciprocal value of the period Tp of the pressure pulses. Instead of or in addition to this, however, it is also possible for the quantity of fuel injected per unit distance travelled by a vehicle driven by the internal combustion engine to be determined by forming the quotient between the quantity of fuel injected per unit of time and the measured speed of travel v of the vehicle. It can be of advantage, depending on the particular application, to determine the momentary timerelated fuel consumption or the momentary distance-related fuel consumption.In order, for example, to enable a substantially stable reading to be obtained, it can be of advantage to determine the average time value of the quantity of fuel injected per unit of time or per unit of distance.

Another embodiment of the invention is characterised in that the total fuel consumption is determined by adding up the quantities of fuel injected per work cycle or by integrating as a function of time, the quantities of fuel injected per unit of time. In this way, it is possible, for example, to obtain an indication of the fuel reserve still available.

In another embodiment of the invention, the quantity of fuel injected may be used not only for indication purposes but also as an engine control quantity for optimising fuel consumption and for reducing pollutant emission. In this way, it is possible to optimise the entire operational cycle.

The present invention also relates to an arrangement for carrying out the method which is characterised by a sensor designed to be connected to an injection system behind its injection pump for generating first signals corresponding directly or indirectly to the output fuel pressure pulses of the injection pump, by means for generating from the first signals second signals which correspond to the particular injection duration T6 and injection period Tp per work cycle and by a central memory-computer unit, such as a microprocessor with an ROM memory connected thereto, which determines from the second signals and stored pump-specific characteristic quantities the quantities of fuel injected per work cycle and/or the quantities of fuel injected per unit of time as third signals optionally averaged out as a function of time.An arrangement such as this is extremely simple and inexpensive and, without any need for the injection pump to be modified, enables the particular quantities of fuel injected to be very accurately determined with the assistance of only one sensor to be connected up behind the injection pump. Whereas the memory-computer unit may in principle be constructed virtualiy as required, the use of a microprocessor with an ROM-memory connected thereto is particularly advantageous and inexpensive. With electronic components such as these, the necessary data may be reliably processed very quickly and accurately on a large scale despite a minimal space requirement.

In another preferred embodiment of the invention, a pressure sensor is connected to the output delivery pipe of the injection pump. In this way, the pressure variations may be detected directly and quickly. Instead of this, it is also possible to use a strain gauge connected to the output delivery pipe of the injection pump which indirectly determines the pressure pulses by detecting changes in the diameter and/or length of the delivery pipe. In another indirect measuring system, a displacement sensor is advantageously used for detecting the opening movement of a closing member-biassed in the closing direction-of an injection nozzle following the injection pump. An inductive displacement sensor may be used for this purpose. The closing element of the known injection nozzles is moved in the opening direction by the pressure which builds up during the effective delivery stroke of the injection pump, so that the movement of the closing member may also be used for determining the pressure pulses. Where an inductive displacement sensor is used, mechanical friction influences and wear phenomena are completely avoided.

Another preferred embodiment of the invention is characterised in that a sensor coupled to a transmission output shaft is used for generating speed-proportional signals and means responding thereto, such as the central memory-computer unit itself, are used for converting the quantity of fuel injected per unit of time into a distancerelated fuel consumption value. This embodiment of the invention represents a very simple on-board facility for determining all the necessary fuel consumption data.

Embodiments of the present invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a graph showing the pressure trend of the fuel as a function of time in the output pressure line of the injection pump.

Figure 2 is a graph illustrating the dependence of the stroke curve of the piston injection pump upon the angular position of the driving camshaft.

Figure 3 is a diagrammatic general view of one embodiment of the arrangement according to the present invention.

Figure 4 is a block circuit diagram of an evaluation circuit which may be used in the arrangement according to the invention.

Figure 5 is a diagrammatic partial elevation of a displacement sensor for indirectly detecting pressure pulses.

When the camshaft of a piston injection pump rotates, i.e. when the camshaft angle P changes as a function of time, the actual stroke h of the pump piston changes between minimum and maximum values (not identified), for example, in accordance with the stroke curve illustrated in Figure 2. The actual delivery stroke always begins at a certain camshaft angle 0 and ends at a variable camshaft angle " according to the required power output of the engine, for example, in dependence upon the particular position of the accelerator pedal.Accordingly, the effective delivery of fuel takes place in the region of the injection angle (p. The effective injection angle SDe is relatively small or relatively large according to the angular position of the pump piston which may be adjusted by a control rod and controlled, for example, by the position of the accelerator pedal. The illustration in Figure 2 applies to an injection pump in which the control edge of the pump piston is situated underneath, so that, after closure at qwO, the fuel return is variably opened at (p, in dependence upon the angular position of the pump piston.If, in the injection pump used, the control edge of pump piston is situated on top, the situation is reversed so that the fuel return of the injection pump is closed at a variable q0 depending on the rotation of the piston and reopened at a fixed ,.

As can be seen from Figure 2, the pump piston completes an effective delivery stroke He during the injection angle fet this effective delivery stroke He being the difference between the variable maximum stroke H1 at the end of injection and the fixed minimum stroke Ho at the beginning of injection. One such injection stroke He occurs once during each period (pp of the camshaft angle.

This angle (pp is measured between two fixed starting points or end points of the successive delivery stroke phases and, in the present case, between the beginnings of two successive delivery stroke phases.

During the delivery stroke phases of the injection pump, the fuel return of the pump is closed so that the fuel flows into the output delivery pipe from which it is injected via a calibrated injection nozzle. Accordingly, an excess pressure builds up in the delivery pipe during the effective delivery stroke phases, as shown in Figure 1. The pressure trend p(t) always shows pressure pulses exceeding a threshold pressure Ps when the injection pump is in its effective delivery stroke phase. As shown in Figure 1 , the pressure pulse begins at the time to and ends at the time t, after a variable injection period Te.Accordingly, the times to and t1 coincide with the occurrence of the camshaft angles 0 and 1. Commensurate with the periodic stroke curve in Figure 2, with the periodic camshaft angle (pp, the pressure pulses also occur periodically with period Tp. Where an injection pump in which the beginning of injection is fixed at Co, is used, this value is measured between the initial or rising pulse sides of two successive pressure pulses. Where an injection pump in which the end of injection is fixed at , is used, the injection period Tp is measured between the terminal or falling sides of successive pressure pulses, as indicated in Figuare 1 by a chain-line double arrow.

The quantity of fuel injected per work cycle of the injection pump is the product of the piston area of the pump and the effective delivery or injection stroke He. This applies to all piston injection pumps with the control edge of the piston situated on top or underneath.

Accordingly, the injection duration Te and the injection period Tp for each work cycle may be determined from the pressure pulses in the pressure line behind the injection pump. The following relationship exists between these values and the camshaft angles: Tp T (pp (pe From this, the injection angle is obtained as:: Te (pe=(pp T p Since the periodic camshaft angle (pp is known and amounts, for example, to 3600, the injection angle ve can be worked out using the determined ratio Te /top. Since, on the other hand, the beginning of injection is fixed at q70, a certain injection stroke He may be worked out from the pump-specific stroke curve h using the determined (p. A certain injected quantity per work cycle is associated with that certain injection stroke He via a certain piston area.

Accordingly, it is possible to assign a certain injected quantity of fuel per work cycle to each ratio Te/Tp. At the same time, the rotational speed n may be determined from the determined injection period Tp by formation of the reciprocal value.

As shown in Figure 3, a fuel tank 10 is connected by a suction pipe 1 2 to a main delivery pump 14 of which an output pressure line 1 6 is connected through a fuel filter 1 8 to a suction pipe 20 of an injection pump 22. An output pressure or delivery pipe 24 of the injection pump 22 is provided with a pressure sensor 26 comprising a signal line 28 and leads to the inlet of a known injection nozzle 30 which in turn injects the fuel into the working space of an automatic-ignition internal combustion engine 34 during the effective delivery stroke of the injection pump 22. A fuel return line 36 connects the injection nozzle 30 to the fuel tank 10.

The injection nozzle 30 contains in known manner (not shown) a spring-biassed, displaceable closing member which opens a calibrated nozzle orifice and closes the return line 36 during the effective delivery stroke or rather injection stroke He of the injection pump 22. In cases where the displaceable closing member is, for example, inductively coupled to a displacement sensor which detects its opening movement, there is no need for the pressure sensor 26 with the signal line 28 and signal line 32 connected to the displacement sensor and shown in chain lines in Figure 3 is used instead. In either case, the electrical signals in the signal line 28 or 32 represent the pressure pulses shown in Figure 1.

The pressure pulses determined are fed into a central memory-computer unit 38 which determines the injection duration Te and the injection period Tp therefrom. The injection angle qDe may be calculated from those values in the manner already described and, through stored function values of the stroke curve, enables the particular injection stroke He and hence the quantity of fuel injected per work cycle to be determined. An indicating instrument 40 may indicate, for example, the quantity of fuel injected per work cycle, the quantity of fuel injected per unit of time or the total quantity of fuel hitherto injected. Similarly, the rotational speed n may be indicated as the reciprocal value of the injection period Tp either by an indicating instrument 40 or by another suitable instrument.

If desired, other operating parameters A, such as, for example, a temperature and/or pressure signal, may also be taken into consideration in the central memory-computer unit. In addition, the output signal(s) of a memory-computer unit 38 may be delivered to an additional signal processing unit 42 which generates, for example, an output signal B for engine control purposes or the like.

For a distance-related fuel consumption reading of a vehicle driven by the automaticignition internal combustion engine 34, it is necessary to deliver a speed-proportional signal to the central memory-computer unit 38. To this end, a rotary sensor 46 may be coupled to a transmission output shaft 44 of the vehicle, delivering a speed-proportional signal to the central memory-computer unit 38 via a signal line 48. By forming the quotient between the quantity of fuel injected per unit time and the measured speed of the vehicle, it is possible to determine and indicate the momentary consumption of fuel per unit distance travelled.

Figure 4 shows one example of embodiment of the central memory-computer unit 38 appearing in Figure 3. The pressure signal p(t) in Figure 1 is converted in a sensor 50 into counter activation signals XE and Xp which cause a following counter unit 52 to generate output counting signals NE and Np corresponding to the injection duration Te and to the injection period Tp. These counting signals are delivered to a microprocessor 54 which is coupled to an ROM-memory 56.

Whereas the microprocessor is capable of performing various conversion functions, such as, for example, determination of the rotational speed n from the counter signal Np representing the injection period Tp, functional relations between the particular quantity of fuel injected Ve and the quantities Te and Tp and, optionally, n are stored in pump-specific form in the ROM-memory 56.

After interrogation of the ROM-memory 56, the microprocessor 54 is able at its output end to release an electrical signal representing the particular quantity of fuel injected Ve. In the present case, the rotational speed n is also made available in the form of an electrical signal. The quantity of fuel injected Ve may again be determined per work cycle, per unit of time or per unit of distance travelled and, optionally, as a function of time. Information on the overall transmission ratio between the engine speed and the wheel speed is delivered to the processor in the form of the value i. In addition, the overall fuel consumption may be indicated. Depending on the application, it is necessary or possible to feed further parameters into the microprocessor 54, these further parameters optionally being taken into consideration in the identification field of the ROM-memory 56.

Instead of storing injected quantities of fuel corresponding to different pairs of values Te and Tp, it is also possible in principle to calculate the injection stroke He from a stored stroke function h using the quantities Te, Tp and then to calculate the quantity of fuel injected Vie from that injection stroke He via the piston area.

Figure 5 shows diagrammatically that the injection nozzle 30 appearing in Figure 3 is provided internally with a closing element 58 in the form of a displaceable needle which is biassed by means of a closing spring 60 in the closing direction of a nozzle orifice (not shown) which opens into the working space of the internal combustion engine 34. It is assumed that, in the case illustrated, the closing element 58 is in its lower position in which it closes the nozzle orifice.

At the beginning of the effective delivery stroke of the injection pump 22, a force acting upwards in the direction of the arrow C is applied to the closing element 58 by the fuel introduced under pressure into the injection nozzle 30, so that the closing element 58 is moved upwards against the biassing of the closing spring 60, releasing the nozzle orifice. As a result, fuel can be injected through the nozzle orifice into the internal combustion engine 34. At the end of the effective delivery or injection stroke of the injection pump 22, the closing spring 60 presses the nozzle needle or rather the closing element 58 downwards again so that the nozzle orifice remains closed for the remaining times, thereby avoiding combustion reactions.A certain minimum pressure is required for opening the closing element 58, although this minimum pressure is lower than the working pressure of the fuel, i.e. the pressure required to force the fuel through the calibrated nozzle orifice. The opening movement of the nozzle needle or rather the closing element 58 which takes place in the direction of the arrow C substantially coincides with the occurrence of the pressure pulses appearing in Figure 1. Accordingly, these pressure pulses may also be determined by detection of the opening movement of the closing element 58.

To this end, a stationary electrical coil 62 surrounding an iron core 64 and having coil connections 66 may be associated with the rear end of the closing element 58 at a distance therefrom and within the closing spring 60 in such a way that a variable interval equal at most to S, and at least to S2 is adjusted between the stationary end of the iron core 64 and the moving end of the closing element 58. The inductance of the electrical coil 62 changes as a result of this variable interval or gap so that, providing it is suitably supplied with electricity, the coil 62 is able to generate electrical pulses corresponding to the opening movements of the closing element 58 and hence to the pressure pulses appearing in Figure 1.

In principle, the opening movements of the closing element 58-in the form of a nozzle needle-of the injection nozzle 30 could also be detected otherwise, for example capacitively or optically. It is also possible to use strain gauges in order, for example, to determine changes in the diameter or length of the delivery pipe 24 in consequence of the pressure pulses.

The pressure pulses or quantities determined therefrom need only be qualitatively detected so far as their respective beginnings and ends are concerned to enable the injection duration Te and the injection period Tp to be determined therefrom. By contrast, the absolute magnitude of the pressure pulses which which can differ greatly from case to case is totally immaterial to determination of quantity of fuel injected by the process according to the invention. To this extent, it is possible fairly easily to determine the quantity of fuel injected per work cycle very accurately, quickly and reliably.

The embodiments illustrated are merely examples of embodiment which may be modified in many different ways. In this connection, it is important that, without the injection pump being modified in any way, the pressure pulses occurring in operation are determined directly or indirectly behind the pressure pump in the pressure line thereof to enable the pulse duration to be determined therefrom as the injection duration Te and the pulse interval as the injection period Tp, so that the particular quantity of fuel injected can be determined with the assistance of a stored pump-specific characteristic field. The method according to the invention is extremely simple and may even be used in already existing injection systems without any significant structural modifications. The individual measures to be taken may be modified in many ways and adapted within wide limits to the particular operating requirements.

Claims

1. A method for determining the quantity of fuel injected by means of a camshaft-driven piston injection pump in an automatic-ignition internal combustion engine, wherein the injection duration Te and the injection period Tp per work cycle of the injection pump are determined by direct or indirect detection of the pressure pulses of the fuel-pressure trend as a function of time behind the outlet of the injection pump and the particular injection-active pump delivery stroke or the associated injected quantity of fuel per work cycle is determined from the injection duration and the injection period and from their relationship with the pump-specific delivery stroke curve dependent upon the rotation of the camshaft.

2. A method as claimed in Claim 1, wherein the pressure pulses in the output delivery pipe of the injection pump are directly detected.

3. A method as claimed in Claim 1 , wherein the pressure pulses are indirectly detected by determining changes in the diameter and/or length of the output delivery pipe of the injection pump.

4. A method as claimed in Claim 1, wherein the pressure pulses are indirectly detected by determining the opening movements of an injection nozzle following the injection pump and provided with a closing member biassed in the closing direction.

5. A method as claimed in any one of Claims 1 to 4, wherein the injection angle ve=27rTe /Tp is calculated from the injection duration Te and the injection period Tp, injected quantities of fuel associated with a plurality of different, predetermined values of the injection angle ve corresponding to the pump-specific delivery stroke curve are stored as characteristic quantities, and the stored injected quantity of fuel corresponding to the particular injection angle calculated is determined.

6. A method as claimed in any one of Claims 1 to 4, wherein injected quantities of fuel associated with a plurality of different, predetermined values of the injection duration Te and the injection period Tp corresponding to the pump-specific delivery stroke curve are stored as characteristic quantities in an identification field and the stored injected quantity corresponding to the particular values determined for the injection duration Te and the injection period Tp is determined.

7. A method as claimed in Claim 5 or 6, wherein the quantity injected is determined by interpolation between the stored injected quantities.

8. A method as claimed in any one of Claims 1 to 7, wherein the rotational speed n is determined by forming the reciprocal value of the period Tp of the pressure pulses.

9. A method as claimed in any one of Claims 1 to 8, wherein the quantity of fuel injected per unit time is determined by forming the product between the quantity injected per work cycle and the rotational speed n or the reciprocal value of the period Tp of the pressure pulses.

10. A method as claimed in Claim 9, wherein the quantity of fuel injected per unit distance travelled by a vehicle driven by the internal combustion engine is determined by forming the quotient between the quantity of fuel injected per unit time and the measured speed of travel v of the vehicle.

11. A method as claimed in Claim 9 or 10, wherein the average time value of the quantity of fuel injected per unit of time or unit of distance is determined.

1 2. A method as claimed in any one of Claims 1 to 11, wherein the total fuel consumption is determined by adding up the quantities of fuel injected per works cycle or by integrating as a function of time the quantities of fuel injected per unit time.

13. A method as claimed in any one of Claims 1 to 12, wherein the injected quantity determined is used as an engine control quantity for optimising fuel consumption and for reducing pollutant emission.

14. A method for determining the quantity of fuel injected by means of a camshaft driven injection pump in an automatic-ignition internal combustion engine substantially as herein described with reference to the accompanying drawings.

1 5. An arrangement for determining the quantity of fuel injected by means of a camshaft driven piston pump in an automatic-ignition internal combustion engine, the arrangement comprising a sensor designed to be connected to an injection system behind its injection pump for generating first signal corresponding directly or indirectly to the output fuel pressure pulses of the injection pump; means for generating from the first signals second signals corresponding to the particular injection duration Te and injection period Tp per work cycle, and a central memorycomputer unit, for determining from the second signals and stored pump specific characteristic quantities the quantities of fuel injected per work cycle anD/or the quantities of fuel injected per unit time as third signals (Ve) optionally averaged out as a function of time.

1 6. An arrangement as claimed in Claim 15, wherein the central memory-computer unit comprises a microprocessor with a ROM-memory connected thereto.

1 7. An arrangement as claimed in Claim 1 5 or 16, wherein a pressure sensor is connected to the output delivery pipe of the injection pump.

1 8. An arrangement as claimed in Claim 15 or 16, wherein a strain gauge is connected to the output delivery pipe of the injection pump.

1 9. An arrangement as claimed in Claim 15 or 16, wherein a displacement sensor is provided for detecting the opening movement of a closing memberbiassed in the closing direction-of an injection nozzle following the injection pump.

20. An arrangement as claimed in Claim 19, wherein an inductive displacement sensor is provided.

21. An arrangement as claimed in any one of Claims 1 5 to 20, wherein a sensor is coupled to a transmission output shaft for generating speedproportional signals and means are provided responsive thereto, for converting the quantity of fuel injected per unit of time into a distancerelated fuel consumption value.

22. An arrangement as claimed in Claim 21, wherein the fuel conversion means are provided by the central memory-computer unit itseif.

23. An arrangement for determining the quantity of fuel injected by means of a camshaftdriven piston injection pump in an automaticignition combustion engine substantially as herein described with reference to Figure 3 with or without reference to any of Figures 1, 2, 4 and 5 of the accompanying drawings.