EP0481983B1 - Process and device for controlling the speed of a slow-running multi-cylinder diesel engine - Google Patents

Abstract

The invention concerns a process for the operation of a slow-running multi-cylinder diesel engine, in which a first mean rpm value n^¨B7, averaged over virtually the whole of the engine cycle, is determined, as well as a second mean rpm value nα averaged only over a sector of the cycle corresponding to the distance between two top dead centres. This sector is staggered by an rpm-dependent angle with respect to the top dead centre. The difference n* - n^¨B7 in rpm is controlled by a slow-acting controller and the difference n*-nα is controlled by a quick-acting controller. Both controllers act on the fuel-injection parameters. The slow-acting controller produces only small changes in fuel admission while the quick-acting controller enables action to be taken rapidly in the event of a fault occurring.

Description

The invention relates to a method and a device for speed control of a slow-running, multi-cylinder diesel engine.

Large diesel engines, such as those used to drive ship propellers, synchronous generators or other large systems usually contain only a few cylinders that work on a common shaft and run at low speeds (e.g. less than 100 rpm). This leads to large pulsations of the drive torque and correspondingly strong changes in the angular velocity of the crankshaft during one work cycle.

If a small time constant is set in the speed controllers used for control, these controllers constantly adjust the filling linkage, which specifies the injection pumps of the cylinders and the degree of filling, due to the pulsating actual speed value. Apart from stability problems, the constant mechanical adjustment of the injection pumps causes undesirably high wear on the filling linkage and an unnecessarily large amount of mechanical adjustment work.

On the other hand, jumps in the applied engine torque (e.g. misfiring or other irregularities in combustion) or in the mechanical load torque (e.g. when the ship's propeller emerges from the water in rough seas) can lead to fluctuations in speed, which must be absorbed in good time in order to stop or overturn to avoid the engine. The speed controller must therefore not be set too slowly.

The systems commercially available on the market therefore work worse than a manually adjusted filling rod, especially at speeds below 20 rpm. Machines with 4 to 6 cylinders are currently not satisfactorily mechanically controllable at around 15 rpm.

For internal combustion engines, particularly in motor vehicles, a regulation is described in European patent application 120 730, in which a sensor for marks attached to the crankshaft generates a reference pulse each time one of the cylinders is at its top dead center. This divides the angle of rotation of the crankshaft into angular ranges. In steady-state operation, the crankshaft takes the same time to run through each angular range, but in the case of irregularities, this time deviates from the mean value averaged over several angular ranges. In order to correct an asymmetry in the operation of the various cylinders, the deviations measured in several work cycles are integrated for each cylinder and a pre-setting of the degree of filling common to all cylinders is corrected with a correction variable formed from this integral.

This corresponds to an integral control that corrects periodic irregularities, such as those caused by asymmetrical operation of the cylinders. The short-term faults mentioned (misfiring or replacement of the propeller) cannot be corrected quickly enough.

An injection pump for a diesel engine is known from EP 0 113 510 A2, which has an adaptive engine torque compensation device. The relative acceleration of each cylinder is measured and the amount of fuel to be injected is adapted for each cylinder to compensate for this.

The invention has for its object to provide a control of slow-running, multi-cylinder diesel engines, which also allows temporary disturbances to be corrected. The problem arises, in particular, of identifying such short-term faults and, if necessary, quickly detect that the control of the engine can be corrected appropriately. Such a speed detection is therefore also an object of the invention.

To solve this, a method and a device for speed control according to the invention is specified in claims 1 and 10.

Angular positions of the crankshaft are defined for each of the cylinders, which represent the start angle and end angle of an angular range lying before the top dead center of the cylinder. This can be done by a sensor for corresponding marks rotating with the crankshaft or another reference pulse generator, which emits a reference pulse each time it passes through one of these defined angular positions.

An actual value n _α is now continuously measured for these angular ranges, indicating the average speed at which the crankshaft traverses this angular range. Furthermore, the speed averaged over several of these angular ranges n the crankshaft measured. So there is a first, sluggish actual speed value n and a second actual speed value n _α , averaged over only part of the work cycle.

. Auch bei unsymmetrischem Betrieb der Zylinder gilt immer noch ungefähr n = n*. Dies ist sofort ersichtlich, wenn n die über einen gesamten Arbeitstakt gemittelte Geschwindigkeit ist, d.h. wenn im stationären Zustand die Summe der Winkelbereiche den ganzen Arbeitstakt ergeben, also ein Winkelbereich gerade dem Drehwinkel der Kurbelwelle zwischen zwei benachbarten oberen Totpunkten der Zylinder entspricht.In steady-state operation, where the drive torque of all cylinders contributes equally to maintaining a target speed n *, these two mean values are approximately the same: ${\text{n}}_{\text{α}}\text{=}\overline{\text{n}}\text{= n *}$

. Even with asymmetrical operation of the cylinders, the approximation still applies n = n *. This is immediately apparent when n the over an entire work cycle is the average speed, ie when the sum of the angular ranges in the steady state results in the entire work cycle, that is, an angular range corresponds exactly to the angle of rotation of the crankshaft between two adjacent top dead centers of the cylinders.

Therefore, the sluggish average speed n compared with the speed setpoint n * and fed to a slow controller which determines a first setpoint for the control of the injection pumps and thus specifies the pre-setting of the filling level of all cylinders. In the case of asymmetries, the output signal of this slow controller practically does not change, and even short-term disturbances hardly change.

The continuously measured actual speed values n _α are also compared with the desired speed value and fed to a fast controller. If a one-off or periodic fault occurs in a cylinder, the actual value n _α and therefore also a second setpoint, which is provided by the output signal of this fast controller, responds quickly to this change. The angular range in which this disturbed actual value n _{α was} formed lies before the top dead center of the cylinder to which this angular range is assigned. The quick correction of the presetting therefore affects at least this cylinder and its degree of filling, which therefore corrects this malfunction immediately. If, as a result of this intervention, this disturbance subsides so quickly that actual speed values n _α , which are measured in subsequent angular ranges, no longer deviate from the target value n *, then the preset degree of filling of the other cylinders is not corrected either.

The method for symmetrizing the operation described in the European application 120 730 mentioned can also advantageously be used.

The described intervention for correcting the disturbances or asymmetries is all the more effective the shorter the time between the fault detection and the correction of the degree of filling of the next cylinder. The end angle of the angular range should therefore be as close as possible to the top dead center of the assigned cylinder. On the other hand, the adjustment of the degree of filling, which takes place via the filling linkage of the corresponding injection pump, should be completed before top dead center is reached. Therefore, the position of the angular range, that is to say the reference positions determining its start angle and end angle, is advantageously adjusted as a function of the speed of the crankshaft. This can be done by means of a corresponding control device.

Advantageous refinements and developments of the invention are characterized in the subclaims. The invention is explained in more detail using two exemplary embodiments and 5 figures.

• Fig. 1 die Hardware-Teile einer bevorzugten Ausführungsform der Erfindung,
• Fig. 2 dabei auftretende Impulse und Meßgrößen,
• Fig. 3 und 4 eine Prinzipdarstellung zweier vorteilhaft verwendeten Regeleinrichtungen und
• Fig. 5 die dabei auftretenden Referenz-Winkelstellungen der Kurbelwelle.

It shows:

• 1 shows the hardware parts of a preferred embodiment of the invention,
• 2 occurring impulses and measured quantities,
• 3 and 4 a schematic diagram of two advantageously used control devices and
• Fig. 5 shows the resulting reference angular positions of the crankshaft.

The invention is explained using the example of a 4-cylinder two-stroke engine, the 4 cylinders Z1, Z2, Z3 and Z4 of which are symbolically shown in FIG. Fuel is injected into the displacement of each cylinder during the compression phase of injection pumps P1, ... P4, the amount of which in relation to the combustion air is determined by the degree of filling F. For this degree of filling, a target value F * is specified, from which a degree of filling controller FR forms a corresponding target value F **, with which, for example, by means of hydraulic operations Filling linkage of the injection pumps is adjusted, the corresponding position of the injection pump being fed back into the filling level controller via the actual value F. It can be provided that the degree of filling regulator acts jointly on the filling linkage of all injection pumps and adjusts all injection pumps together. However, there are preferably individually adjustable injection pumps or individually adjustable injection pumps.

In the position shown in Fig. 1, the cylinder Z1 is at its top dead center, which initiates its first work stroke, the expansion stroke, while the cylinder Z3 is at its bottom dead center, at which its expansion stroke is completed and the second work stroke, the compression stroke is initiated. Accordingly, the cylinder Z2 is still in the middle of its second work cycle (compression), while Z4 is already in the expansion cycle.

In order to ensure proper combustion in engines with electrical ignition in the expansion cycle, the ignition point must be synchronized with the cylinder position and thus the rotational movement of the crankshaft. In the case of diesel engines, the injection nozzle is automatically released by the movement of the piston, but the invention also provides for detection of the angle of rotation of the crankshaft, which is achieved by a corresponding reference pulse generator. This can be an angle detector which acts in the manner of a contactless proximity switch, a slip-less driven incremental angle encoder or another digital or analog working detector circuit coupled to the crankshaft.

erfaßt werden kann.In the case shown, a measuring disc is attached to the crankshaft directly or via a gearbox with the ratio 1: 1, which bears a number ml of brands M. Are defined If a certain initial position of the crankshaft is used as the zero point, the detector DET therefore generates a pulse after each rotation by dγ = 360 ° / ml, so that the number m of pulses that have been generated since the initial position was passed, the angular position $\text{γ = m. dγ}$

can be detected.

The starting position can be detected with every revolution by a zero pulse transmitter, e.g. a mark N which emits a corresponding zero pulse when it passes a zero pulse detector DN. Another pulse generator DN 'is offset from the zero pulse generator DN or the detector DET, in order to determine the direction of rotation of the shaft in a known manner and thus to determine the sign when counting the pulses of the detector DET. The zero pulse of the detector DN can also be used to synchronize the counter required for counting the pulses of the detector DET each time the initial position is passed and to correct any counting errors caused by interference pulses. If such a correction is not necessary, the starting position can also be detected in software by means of the counter for the pulses from DET.

der Impulse des Detektors DET teilt also den ganzen Arbeitszyklus in einzelne Winkelbereiche ein. Jeder der z Winkelbereiche ist einem Zylinder zugeordnet und ist durch Referenzstellungen, die den Anfangswinkel und Endwinkel angeben, festgelegt.In the simplest case, a rotation angle range α = 360 ° / z is defined in accordance with the number z of cylinders firing one after the other, which indicates that after each rotation by this angle α, a cylinder (e.g. Z2) assumes the position that the previous cylinder ( eg Z1) has accepted. This angle α or the corresponding number ${\text{m = m}}_{\text{α}}$

the pulses from the detector DET thus divide the entire working cycle into individual angular ranges. Each of the z angular ranges is assigned to a cylinder and is defined by reference positions that specify the start angle and end angle.

wobei ml die Zahl der pro Zyklus den Detektor DET passierenden Marken M ist. Sind die Marken über ein Getriebe mit dem Übersetzungsverhältnis $\frac{\text{m2}}{\text{ 2}}$

: 1 an die Kurbelwelle gekoppelt, wobei m₂ die Zahl der Arbeitstakte pro Motorzyklus ("Taktzahl" m₂ = 2 für Zweitaktmotoren, m₂ = 4 für Viertaktmotoren) bezeichnet, so ist m₁ die Zahl der Marken auf der Impulsscheibe, während bei einer direkten Ankopplung gilt:

Der Detektor DET und ein Zähler CT mit einem, den momentanen Drehwinkel γ der Kurbelwelle beschreibenden Ausgangssignal sowie ggf. der Nullimpulsgeber DN und der entsprechende Vorzeichendetektor SIGN für das Vorzeichen der Drehrichtung mit seinem Hilfsdetektor DN' stellen also einen Referenzimpulsgeber dar, der bei vorgegebenen Referenzstellungen (also z.B. jeweils dem ersten oberen Totpunkt eines Zylinders während eines Motorzyklus) jeweils einen Referenzimpuls abgibt. Aus diesen Referenzimpulsen bildet eine Meß- und Regeleinrichtung MR, die teils softwaregesteuert und digital und aus Sicherheitsgründen teils auch mechanisch, hydraulisch etc. arbeitet, einen ersten Mittelwert n, der die mittlere Geschwindigkeit angibt, mit der ein jeweils über einen ganzen Arbeitszyklus oder zumindest einen mehrere Winkelbereiche α umfassender, großer Winkelbereich durchlaufen wird. Dieser Mittelwert n kann z.B. als reziproker Wert des Zeitintervalles zwischen zwei Referenzimpulsen des Nullimpuls-Gebers DN erfaßt werden.In four-stroke engines, each cylinder passes through top dead center twice in one engine cycle. In order to record an entire work cycle, two revolutions of the crankshaft must be combined to form an engine cycle. The number ml of the angular increments dγ assigned to an angular range α thus doubles and the initial position assigned to the first top dead center of the cylinder Z1 in one work cycle is only reached after passing the mark N twice on the detector DN. In the general case, the assignment of the angular range number m _α to the angular ranges α is according to the formula

${\text{m}}_{\text{α}}\text{= ml / Z,}$

where ml is the number of marks M passing through the detector DET per cycle. Are the brands about a gearbox with the gear ratio $\frac{\text{m2}}{\text{2nd}}$

: 1 coupled to the crankshaft, where m₂ denotes the number of work cycles per engine cycle ("number of cycles" m₂ = 2 for two-stroke engines, m₂ = 4 for four-stroke engines), so m₁ is the number of marks on the pulse disk, while with a direct coupling applies :

The detector DET and a counter CT with an output signal describing the instantaneous angle of rotation γ of the crankshaft and possibly the zero pulse generator DN and the corresponding sign detector SIGN for the sign of the direction of rotation with its auxiliary detector DN 'thus represent a reference pulse generator which, at predetermined reference positions ( for example, each gives a reference pulse to the first top dead center of a cylinder during an engine cycle). A measuring and control device MR, which is partly software-controlled and digital and partly works mechanically, hydraulically, etc. for safety reasons, forms a first mean value from these reference pulses n , which indicates the average speed at which each cycle spans an entire work cycle or at least one large angular range encompassing several angular ranges α. This mean n can be detected, for example, as the reciprocal value of the time interval between two reference pulses of the zero pulse transmitter DN.

In addition, a second mean value n _{α is} formed in the measuring and control device MR, which indicates the speed at which the crankshaft each has an angular range α (or another small angular range, each assigned to one of the cylinders, which is determined by corresponding reference positions of the crankshaft or of the cylinder in question) passes through. The speed value n thus represents an actual value averaged with a large time constant, which is practically influenced in the same way by the mechanical moment applied by all cylinders. The second mean value n _α, on the other hand, represents a value averaged with a small time constant, which mainly includes the last expansion stroke of a cylinder and its influence on the shaft.

As will be explained later, the measuring and control device MR contains an inert controller, which measures the mean value n compares with a speed setpoint n * and from this specifies a setpoint for presetting the filling level of the cylinders. In addition, a fast controller for the difference n * - n _{α is} provided, the output signal of which is superimposed on the output signal of the slow controller and can therefore quickly adjust the degree of filling at any time before the next expansion stroke of a cylinder.

One advantage of detecting two speed values averaged with different time constants is, for example, that it is possible to regulate the sluggish mean value, which applies the pulsed profile of the cylinders Engine torque M _diesel regulates without constant adjustment of the controller setting. The mean value n _α, on the other hand, makes it possible to intervene quickly in the event of faults. For example, more frequent misfires of a cylinder can be recognized and corrected by suitable interventions on this cylinder and / or corrected each time the next cylinder is filled. Likewise, short-term exceedances of limit speeds can be reported and suitable protective measures can be triggered before the slow control required for stable engine operation can respond. In particular, the angular ranges assigned to the individual cylinders and the mean values n _α measured therein can be displayed and documented, which provides valuable conclusions with regard to the further service of the system.

The detection of the angular velocity n _α described so far is essentially known from the already mentioned European patent application 120 730 for internal combustion engines and makes it possible to increase the concentricity of the engine by compensating for irregular combustion in the cylinders. However, the top dead center of a cylinder is the starting position of the assigned cylinder, so that in the angular range only the influence of this cylinder on M _diesel is recorded as far as possible.

However, in order to be able to adequately correct individual faults that occur, it is advantageous if the detection and the intervention for eliminating this fault have already been completed before a cylinder is again filled before its expansion stroke. The end angle of the angular range required for the n _α measurement must therefore be sufficiently far before the top dead center of the assigned cylinder.

On the other hand, this fault message should be as close as possible to the time of injection. Because the filling rods and If the injection pump needs a certain time to regulate the degree of filling, the determination of the mean value n _{α is} controlled as a function of the speed.

This means e.g. for the cylinder Z1 that an angle range α is assigned to it by specifying a starting angle and an end angle for the position of the crankshaft, the end point of which at low speeds is just before the position at which this cylinder Z1 reaches its top dead center. At high speeds, however, this end angle is advanced.

For this purpose, the measuring and regulating device contains a control device controlled by the average speed, as will be explained in more detail below with reference to the signals in FIG. 2 and a schematic circuit in FIG. 3.

2 shows the output signal of a time pulse transmitter clk operating at a constant frequency. The curve n (t) gives the instantaneous speed of rotation, ie the time derivative dγ / dt of the angle of rotation γ of the motor shaft. Compared to the long-term mean value n _av , this actual value shows significant drops at times t1 ... t4, at which the cylinders reach their top dead center. At time t1, which coincides with a zero pulse m _{D of} the zero pulse detector DN, the combustion in the cylinder Z1 increases the thrust on the axis of rotation and thus the speed of rotation, but this speed decreases due to the decreasing expansion pressure and because of the work required for compression in the cylinder Z2 . In Fig. 2 it is exaggerated that the expansion pressure in the individual cylinders takes on different values after passing through their top dead center and therefore an irregular course of the speed arises.

A first counter CT1 counts the time pulses clk between the occurrence of two zero pulses m _D. With every zero pulse the counter reading ct1 is placed in a corresponding memory M1, at the output of which the reciprocal of the counter reading multiplied by the output signal sign for the duration of the next revolution of the crankshaft n of the direction of rotation detector SIGN, as a corresponding, long-term average n is available.

The pulses m of the reference pulse generator each indicate that an angular range has been reached and left and are supplied to another counter CT2 for the time pulses clk. They determine the points in time at which the counter reading ct2 of the counter CT2 shown in FIG. 2 is in each case read into a memory M2 and reset.

den Anfang dieses Winkelbereiches angeben. Die Referenzstellung γ2 ist dabei gegenüber dem oberen Totpunkt des Zylinders Z2 (Zeitpunkt t2) um den Verschiebungswinkel dα vorverlegt. Zum Zeitpunkt t2' ist also die Mittelwertbildung im Winkelbereich α bereits abgeschlossen und der Zähler Z2 liest seinen Zählerstand in den Speicher M2 ein. Der zu n_α proportionale Wert sign $\overline{\text{n}}\text{. (1/ct2)}$

wird über den schnellen Regler das Füllungsgestänge für den Zylinder Z2 verstellen, bevor dieser Zylinder seinen oberen Totpunkt erreicht.For example, the cylinder Z2 is assigned the reference position γ2 of the cylinder axis as the end point of its assigned angular range and the corresponding time t2 ', while the time t1' and the reference position $\text{γ1 = γ2 - α}$

indicate the beginning of this angular range. The reference position γ2 is advanced from the top dead center of the cylinder Z2 (time t2) by the displacement angle dα. At time t2 ', the averaging in the angular range α has thus already been completed and the counter Z2 reads its counter reading into the memory M2. The value sign. Proportional to n _α $\overline{\text{n}}\text{. (1 / ct2)}$

will adjust the filling linkage for cylinder Z2 via the fast controller before this cylinder reaches its top dead center.

In Fig. 2 it is assumed that m _α = 9, ie there are nine incremental angular steps dγ between the top dead centers of two adjacent cylinders. The corresponding control pulses, which correspond to the reference angular positions γ1 and γ2, are formed by the reference pulse generator from the pulse train of the detector DET in that this pulse train is fed to the counter CT mentioned, whose counter reading ct is set at a reference position to the value m _α and counted down. When the value reaches zero, the next reference pulse is given and the counter is set again.

vorverschoben.The synchronization to the zero pulse m _D can take place, for example, in that the counter reading is set to a corresponding value in each case with a zero pulse, in FIG. 2 to the value ct = 7. The end position γ2 for the angular range α assigned to the cylinder C2 is then always reached after 7 incremental angular steps dγ and around the corresponding top dead center of the cylinder Z2 $\text{dα = 2. dγ}$

advanced.

und aus der Im Zähler CT2 gemessenen Zeit T zwischen den Referenzimpulsen gebildet wird, ändert sich nur unwesentlich, wenn der Zähler CT2 jeweils auf den einem veränderten Winkelbereich α' entsprechenden Zählerstand m_α, gesetzt wird. Dies ist in Fig. 2 zum Zeitpunkt t3' dargestellt, bei dem der Zählerstand m = 10 vorgegeben wird. Dadurch ist für den Zylinder Z4 ein Winkelbereich $\text{α'= 10.dγ}$

bestimmt, so daß sich für die Referenzstellung γ4 dieses dem Zylinder Z4 zugeordneten Intervalls der Wert $\text{γ4 = γ3 + α' = γ3+10.dγ}$

ergibt. Im Speicher M2, der durch den Endzustand des Zählers beim Referenzimpuls γ4 die Zeit T erfaßt, wird dann der Mittelwert ${\text{n}}_{\text{α}}\text{= α'/T}$

gebildet, indem der im Zähler stehende, veränderte Wert des Winkelbereichs α' berücksichtigt wird.In practice, the top dead centers of the cylinders are not always reached exactly with pulses from the pulse generator DET or with a zero pulse. However, this is not necessary either, and likewise the angular range α, which is assigned to the cylinders one after the other, neither has to be exactly the same nor correspond to the angular distance between the top dead centers of the cylinders. Since it is only a matter of averaging, a somewhat shorter angular range can be assigned to a cylinder, for example, the time required to pass through this angular range also being shortened. The average speed n _α , which is given as

and is formed from the time T measured in the counter CT2 between the reference pulses changes only insignificantly when the counter CT2 is set to the counter reading m _α corresponding to a changed angular range α '. This is shown in FIG. 2 at time t3 ', at which the counter reading m = 10 is specified. This creates an angular range for cylinder Z4 $\text{α '= 10.dγ}$

determined so that the value for the reference position γ4 of this interval assigned to the cylinder Z4 $\text{γ4 = γ3 + α '= γ3 + 10.dγ}$

results. In the storage room M2, which detects the time T through the final state of the counter at the reference pulse γ4, then becomes the mean value ${\text{n}}_{\text{α}}\text{= α '/ T}$

formed by taking into account the changed value of the angular range α 'in the counter.

The averaging can also take place over angular ranges α, which are in each case smaller than the distance between the top dead centers. While in FIG. 2 each a reference position indicates the end value of an angular range and at the same time the start value of the next angular range, separate start and end positions can also be defined, pauses then occurring which are not used to form the mean value n _α . As long as the speed remains the same, these pauses are of equal length, but if the relative position of the angular areas to the top dead centers is to be changed when the speed changes, the corresponding shift in the start and end values results in a temporary change in these pauses. It is also possible to select the measurement intervals for averaging to be larger than the distance between the top dead centers, so that these angular ranges overlap one another. A permanent change in speed then causes a temporary change in the overlap.

des Speichers M2, kann wieder auf die bereits besprochene Weise berücksichtigt werden.In the example shown in Fig. 2, however, the angular ranges are chosen such that their sum at the same speed just give the full cycle of the engine. There are therefore no overlaps or pauses, and a reference position simultaneously indicates the end value of the previous measurement interval and the start value of the next measurement interval. The speed-dependent displacement of the relative position between the measuring range and top dead center can be achieved by temporarily changing the measuring range. This is shown in FIG. 2 by the fact that at a zero pulse m _D or the associated time t ' the counter reading ct of the counter CT is not set to the value 7, as is usually provided for the synchronization, but is set to the value 6, for example. The counter CT, which was set to the value m = 9 at the previous reference position as usual and would therefore have reached the counter reading 7 at the time t ', is then reset again after only 8 counting steps and thus ends the counting interval prematurely. This one-time change in the angular range α and the counter in the speed signal ${\text{n}}_{\text{α}}\text{= α / T}$

of the memory M2 can again be taken into account in the manner already discussed.

vorgibt.For this speed-dependent position shift of the angular range α, which in this case takes place via the counter CT in the reference pulse generator, a corresponding function generator FKT is provided in FIG. 2, which performs the corresponding position shift dα or dα 'via the synchronization of the counter CT as a function of rotational speed $\overline{\text{n}}$

pretends.

The mean value n _{α is} more sensitive to the torque pulsations of the drive than the mean value n . With asymmetries in the drive, there is therefore no adjustment of a slow controller R from the speed deviation n * - n a setpoint F * for presetting the filling level. In addition, a controller R _{α is} provided, which is fed by the control deviation n * - n _α . Its output signal F _α *, which is used to correct the presetting and, for example, with an adder AD F * is superimposed additively, the injection pumps can constantly adjust. Since torque pulsations are unavoidable anyway, the controller R _α can be calmed down considerably if speed deviations n * - n _α are not corrected within a predetermined fluctuation range. For this purpose, FIG. 3 provides for a dead element to be connected upstream of the regulator R _α , which only applies a corresponding control signal to the regulator R _α when predetermined limit values for n * -n _{α are} exceeded.

The sluggishness of the regulator R is preferably achieved by using an integral controller or a proportional-integral controller with the essential integral behavior. For the fast controller R _α, on the other hand, a purely proportional or predominantly proportional behavior is preferred.

In particular in the event that the degree of filling of the individual injection pumps can be individually adjusted, the symmetry of cylinder asymmetries already described can be advantageous.

und zu der im Fall der geschilderten Regelung erforderlichen Messung der Drehzahl n_α, benötigt diese Symmetrierung noch die Erfassung von Drehzahlen n_βj, die jeweils möglichst nur den Einfluß eines zugeordneten Zylinders T_j erfassen.In addition to the speed detection n via the counter CT1 (final counter T after each period), the memory M1 and the divider DIV1

and for the measurement of the speed n _α required in the case of the regulation described, this symmetrization also requires the detection of speeds n _{β j} , each of which, if possible, only _detects the influence of an assigned cylinder T _j .

A suitable arrangement for this is shown in FIG. 4. A division into angular ranges β _{j is} required, each beginning approximately at the top dead center of the assigned cylinder. For a 6-cylinder / 2-stroke engine, this angular division is a function of the speed n is specified by a function memory FKT, shown in Fig. 5.

den Zylinder an, dem der Winkelbereich β_j zugehörig ist, und die Winkelstellung p_i gibt dabei den Referenzwinkel an, bei der der Winkelbereich β_j beginnt (oberer Totpunkt von Z_j) und der Winkelbereich β_j-1 des vorangegangenen Zählers endet. Diese Referenzwinkel sind im Funktionsgeber drehzahlunabhängig gespeichert. Falls der geschilderte schnelle Regler vorgesehen ist, geben gerade Zählzahlen i gemäß $\text{j'= i/2+1}$

den Zylinder an, dem der Winkelbereich α_j' zugeordnet ist und die Winkelstellung p_i gibt den Referenzwinkel an, bei dem der Winkelbereich α_j' endet (vor dem oberen Totpunkt von Z_j') und der nächste Winkelbereich α_j'+1 beginnt. Der Abstand dα(n) vom oberen Totpunkt wird vom Funktionsspeicher jeweils bei einem Nullimpuls neu in Abhängigkeit von der Drehzahl nach einer gespeicherten Funktion vorgegeben, wodurch sich also auch die Breite des Bereiches α₂ ändern kann.Twelve angular positions p _{i are} specified as reference positions, which can be counted by a cyclical counter running in a decoder DECOD. An odd count i gives according to $\text{j = (i + 1) / Z}$

indicates the cylinder to which the angular range β _j belongs, and the angular position p _i indicates the reference angle at which the angular range β _j begins (top dead center of Z _j ) and the angular range β _{j-1 of} the previous counter ends. These reference angles are independent of the speed in the function generator saved. If the described fast controller is provided, counting numbers i give in accordance with $\text{j '= i / 2 + 1}$

the cylinder to which the angular range α _{j 'is} assigned and the angular position p _i indicates the reference angle at which the angular range α _j' ends (before the top dead center of Z _{j '} ) and the next angular range α _{j' + 1} begins . The distance dα ( n ) from top dead center is given by the function memory each time a zero pulse depending on the speed after a stored function, which means that the width of the range can also change α₂.

The counter CT is reset in each case at the position p 1 and thus delivers a counting of the incremental angle steps d γ an angle related to p 1, which is compared in the decoder DECOD with the read reference angle p 2. If this angle is reached, the second pulse is generated by DECOD and the reference angle p₃ is read in until a new cycle begins after the twelfth count pulse, the first pulse of which can be triggered by the zero pulse m _D.

zu bilden. Hierzu wurde die Breite α_j' dieses Winkelbereichs mittels dieses Impulses aus dem Funktionsspeicher abgerufen und am Multiplizierer MP mit dem Signal des Drehrichtungsdetektors SIGN multipliziert.For every even count i, the pulse starts the counter CT2 again in the manner described, whose end count T _{α has been} read into the memory M2 by the average speed on the downstream divider DIV2 ${\text{n}}_{\text{α}}{\text{= (α}}_{\text{j '}}{\text{/ T}}_{\text{α}}\text{) .sign}\overline{\text{n}}$

to build. For this purpose, the width α _{j 'of} this angular range was called up from the function memory by means of this pulse and multiplied at the multiplier MP by the signal of the direction of rotation detector SIGN.

wird aber entsprechend seiner Zuordnung zum Zylinder Zj über einen Multiplex-Schalter einer Überwachungseinrichtung (im einfachsten Fall einem Display DIS) zugeführt.For every odd count i, the same process is repeated for the angular ranges β _j by means of the counter CT3 (final counter value T _β ) and the divider DIV3. The resulting mean ${\text{n}}_{\text{βj}}{\text{= βj / T}}_{\text{β}}$

However, according to its assignment to the cylinder Zj, it is fed to a monitoring device (in the simplest case, a display DIS) via a multiplex switch.

unabhängig von den Einspritzpumpen der anderen Zylinder gesteuert.An asymmetry of the cylinders can be _corrected by feeding n _{βi to} a storage device M3. The deviation n * - n _βj can be averaged over several revolutions in order to obtain a correction value F * _j assigned to the cylinder Zj. The degree of filling of the cylinder Zj is then with $\overline{\text{F}}{\text{* + F}}_{\text{α}}\text{* + Fj *}$

controlled independently of the injection pumps of the other cylinders.

und R_α.This and similar interventions stabilize the operation of the controller $\overline{\text{R}}$

and R _α .

Claims (13)

1. Process for the control of a slow-running, multi-cylinder diesel engine, in which

   a1) an angular range (α; α₁ ... α₆) of the engine cycle is assigned to each cylinder Z1 ... Z2) before its top dead centre point (t1, t2, t3 ...),

   a2) a first actual value for the speed ( ${\text{}}_{\overline{\mathit{\text{n}}}}$

   

   ) of the crankshaft is formed by averaging over a number of the angular ranges (α; α₁ ... α₆) , and

   a3) the first actual value for the speed ( ${\text{}}_{\overline{\mathit{\text{n}}}}$

   

   ) is compared with a first set-point value for the speed (n*) and a supplied to a slow-acting controller ( ${\text{}}_{\overline{\mathit{\text{R}}}}$

   

   ) and in which

   b1) angular positions (γ; γ₁ ... γ₆) of the crankshaft are specified which correspond in each case to the ending angle (γ₁ ... γ₆) of the angular range (α; α₁ ... α₆) located before the top dead centre of the cylinder concerned (Z1 ... Z6),

   b2) in which, on reaching the angular position concerned (γ₁ ... γ₆), a second actual value for speed (n_α) of the crankshaft is formed corresponding to the average speed of the crankshaft in the preceding angular range (α; α₁ ... α₆) in each case, and

   b3) in which the second actual value for speed (n_α) is compared with a second set-point value (n*) for speed and supplied to a fast-acting controller (Rα), and in which

   c1) the output signal ( ${\text{}}_{\overline{\mathit{\text{F}}}}$

   

   ) of the slow-acting controller ( ${\text{}}_{\overline{\mathit{\text{R}}}}$

   

   ) is used to preset the fill level for all cylinders (Z1 ... Z6), and

   c2) the output signal (F_α*) of the fast acting controller (R_α) is used to modify the preset value for the fill level for the cylinder (Z1 ... Z6) concerned.
2. Process in accordance with claim 1 characterized in that the slow-acting controller ( ${\text{}}_{\overline{\mathit{\text{R}}}}$

   

   ) has an essentially integral characteristic and the fast-acting controller (R_α) has an essentially proportional characteristic.
3. Process in accordance with claim 1 characterized in that the angular ranges (α; α₁ ... α₆) at least approximately correspond in each case to the angular interval on the crankshaft between the top dead centres of two neighbouring cylinders (Z1 ... Z6).
4. Process in accordance with claim 3 characterized in that the interval (d_α( ${\text{}}_{\overline{\mathit{\text{n}}}}$

   

   )) between an angular range (α₁ ... α₆) and the top dead centre of the cylinder (Z1 ... Z6) assigned is adjusted as a function of engine speed ( ${\text{}}_{\overline{\mathit{\text{n}}}}$

   

   ) .
5. Process in accordance with claim 4 characterized in that, given a uniform speed of rotation ( ${\text{}}_{\overline{\mathit{\text{n}}}}$

   

   ) of the crankshaft, the sum of the angular ranges (α₁ ... α₆) results in the full working cycle of the engine, and that one of the angular ranges (α₁ ... α₆) is temporarily modified in order to modify the interval.
6. Process in accordance with claim 1, characterized in that deviations lying below a specified threshold (DT) are suppressed in the comparison of the second actual value for speed (n_α) with the second set-point value for speed (n*).
7. Process in accordance with claim 1, characterized in that the angular position (γ) of the crankshaft is captured continuously, the angular range (α, α₁ ... α₆) is specified by specification of a starting value and an ending value (γ₁ ... γ₆; p_i), the time (T) between reaching the starting value and the ending value is measured and the second actual value for speed (n_α) is determined from the time measured (T).
8. Process in accordance with claim 1 characterized in that the first actual value for speed ( ${\text{}}_{\overline{\mathit{\text{n}}}}$

   

   ) is determined by measurement of the time required for a full cycle of the engine in each case.
9. Process in accordance with claim 1 characterized in that a measurement is made of average speed of rotation (n_βj) associated with one of the cylinders with which the crankshaft passes through an angular range (β_j) beginning practically at the top dead centre of this one of the cylinders (Z_j), in that the average speed of rotation (n_βj) is compared with a set-point value (n*) and in that by means of which comparison the fill level of the cylinder (Z_j) associated with this speed (n_βj) is corrected.
10. Device for the control of the engine speed of a slow-running, multi-cylinder diesel motor with

    a) an angle detector (DET, CT) coupled with the crankshaft which continuously detects the current angle position (γ) of the crankshaft and which issues a reference pulse each time one of the specified reference angle positions (γ₁, γ₂ ...) of the crankshaft is reached,

    b) means (CT1, M1, DIV1) connected to the angle detector (DET, CT) for the formation of a first average actual value for speed ( ${\text{}}_{\overline{\mathit{\text{n}}}}$

    

    ) with which the crankshaft passed through more than two reference angle positions (γ₁, γ₂ ...),

    c) means (CT2, M2, DIV2) connected to the angle detector (DET, CT) for the formation of a second average actual value for speed (n_α with which the crankshaft passed through an angle range (α₁ ... α₆) defined by two reference angle positions and lying before the top dead centre point of the cylinder concerned,

    d) a slow-acting controller ( ${\text{}}_{\overline{\mathit{\text{R}}}}$

    

    ) fed with the difference ( ${\text{}}_{\overline{\mathit{\text{n}}}}$

    

    - n*) of the first actual value for speed ( ${\text{}}_{\overline{\mathit{\text{n}}}}$

    

    ) and the first set-point value for speed (n*) and which generates a first control signal ( ${\text{}}_{\overline{\mathit{\text{F}}}}$

    

    ),

    e) a fast-acting controller (R_α) fed with the difference (n_α - n*) of the second actual value for speed (n_α) and the second set-point value for speed (n*) and which generates a second control signal (F_α*), and

    f) means (P1, ... , P4) to control the fill level of the individual cylinders as a function of the sum (AD) of the two control signals ( ${\text{}}_{\overline{\mathit{\text{F}}}}$

    

    + F_α*).
11. Device in accordance with claim 10 characterized by means (FKT, ST) which adjust the location of the angular ranges (α, α₁ ... α₆) relative to the top dead centres of the cylinders (Z1 ... Z6) as a function of speed ( ${\text{}}_{\overline{\mathit{\text{n}}}}$

    

    ).
12. Device in accordance with claim 11 characterized by a dead element (DT) for the suppression of small values for the difference (n_α - n*) of the second actual value for speed (n_α) and the second set-point value for speed (n*) at the input to the fast-acting controller (R_α).
13. Device in accordance with claim 11 characterized by means (CT3, DIV3) for the formation of a third average value (n_βj) for the speed with which the crankshaft passes through a further angular range (β_j) associated with a cylinder (Z_j) after passing through the top dead centre point (T_j) of the cylinder, and means (F_j*) for the modification of the fill level of this cylinder (Z_j) as a function of this third average value (n_βj) (Figures 4, 5).

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