EP0406765B1 - Method and apparatus for regulating the rotational speed of a slow-running multi-cylinder diesel engine - Google Patents

Description

The invention relates to a method and a device for speed control of a slow-running, multi-cylinder diesel engine. The invention further relates to a method and a device for speed detection in the 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 a 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 an 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. in the event of misfires or other irregularities in combustion) or in the mechanical load torque (e.g. when the ship's propeller emerges from the water in rough sea conditions) 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, in particular in motor vehicles, a regulation is described in European patent application 120730, 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 stationary 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.

In addition, a speed control is known from EP-A-140065 for a self-igniting internal combustion engine, in which single-cylinder smoothness controls are superimposed by an idle control.

The invention has for its object to provide a control of slow-running, multi-cylinder diesel engines, which also allows temporary malfunctions 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.

For each of the cylinders, angular positions of the crankshaft are defined, 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.

In steady-state operation, in which the drive torque of all cylinders contributes equally to maintaining a target speed n *, these two mean values are approximately the same: n _α = n = 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 if the sum of the angular ranges in the steady state result in the entire working 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 disturbance 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 filling level, 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 *, the preset degree of filling of the other cylinders is not corrected either.

The method for symmetrizing the operation described in the European application 120730 mentioned can also advantageously be used.

The described intervention to correct the disturbances or asymmetries is all the more effective the shorter the time between the disturbance 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, however, 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 five 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 will be explained using the example of a 4-cylinder two-stroke engine, the 4 cylinders Z1, Z2, Z3 and Z4 are shown symbolically 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 The 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 means of a corresponding reference pulse generator. This can be an angle detector, which acts in the manner of a contactless proximity switch, an incremental angle sensor which is driven without slip, or another digital or analog working detector circuit coupled to the crankshaft.

In the case shown, a measuring disk is attached to the crankshaft directly or via a gearbox with the ratio 1: 1, which bears a number m1 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 which have been generated since the initial position was passed through the angular position 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. Offset to the zero pulse generator DN or to the detector DET is a further pulse generator DN '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.

In the simplest case, an angle of rotation range α = 360 ° / z is defined in accordance with the number z of cylinders firing one after the other, which indicates that after each revolution by this angle α a cylinder (e.g. Z2) assumes the position previously assumed by the previous cylinder ( eg Z1) has accepted. This angle α or the corresponding number m = m _{α of} the pulses of the detector DET thus divides 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 indicate the start angle and end angle.

wobei m1 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:
$$\text{m₁ = 2 · }\frac{\text{m₂}}{\text{m₃}}{\text{; m}}_{\text{α}}\text{=}\frac{\text{m₁}}{\text{Z}}$$

With 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 m1 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
$${\text{m}}_{\text{α}}\text{= m1 / Z,}$$

where m1 is the number of marks M passing 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 :
$$\text{m₁ = 2}\frac{\text{m₂}}{\text{m₃}}{\text{; m}}_{\text{α}}\text{=}\frac{\text{m₁}}{\text{Z}}$$

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 regulating device MR contains an inertial 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 pulse-shaped course of the cylinder 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 appropriate 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 previously described detection of the angular velocity n _α is essentially known from the already mentioned European patent application 120730 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 associated 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 to eliminate this fault have already been completed before a cylinder is again filled before its expansion cycle. 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. Since the filling rods and 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 generator 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 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 cylinder Z2 . 2 shows exaggeratedly that the expansion pressure in the individual cylinders assumes 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 put into 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.

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 γ1 = γ2 - α indicate the start 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 proportional to n _α n · (1 / ct2) will use the fast controller to adjust the filling linkage for cylinder Z2 before this cylinder reaches 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 zero is reached, the next reference pulse is given and the counter is set again.

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 advanced by dα = 2 · dγ relative to the corresponding top dead center of the cylinder Z2.

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 α′ = 10 · dγ bestimmt, so daß sich für die Referenzstellung γ4 dieses dem Zylinder Z4 zugeordneten Intervalls der Wert 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 n_α =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 also not necessary and likewise the angular range α, which is assigned to the cylinders one after the other, does not have to be exactly the same or 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, and the time required to pass through this angular range is also shortened. The average speed n _α , which is given as
$${\text{n}}_{\text{α}}\text{= α / T =}\frac{{\text{m}}_{\text{α}}}{\text{m₁}}\text{·}\frac{{\text{2nd}}_{\text{π}}}{\text{T}}$$

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. As a result, an angle range α ′ = 10 · dγ is determined for the cylinder Z4, so that the value γ4 = γ3 + α ′ = γ3 + 10 · dγ results for the reference position γ4 of this interval assigned to the cylinder Z4. In the storage room M2, which detects the time T by the final state of the counter at the reference pulse γ4, the mean value n _α = α ′ / T is then 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 each 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 the same length, but if the relative position of the angular ranges 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 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.

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 in 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 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 n _α = α / T of the memory M2 can again be taken into account in the manner already discussed.

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 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 (output signal: (sign n ) $$\frac{\text{m₁}}{\text{T}}$$

) 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 _βj , each of which, if possible, only _records the influence of an assigned cylinder T _j .

An arrangement suitable 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.

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 specifies the cylinder to which the angular range β _j belongs, according to j = (i + 1) / Z, and the angular position p _i specifies the reference angle at which the angular range β _j begins (top dead center from 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 rapid controller is provided, even count numbers i in accordance with j ′ = i / 2 + 1 indicate the cylinder to which the angular range α _{j ′ is} assigned and the angular position p _i specifies 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 d _α ( n ) from top dead center is given by the function memory each time with 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.

With 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 in order to indicate the average speed n _α = (α _{j ′} / T _α ) · sign on the downstream divider DIV2 n to build. For this purpose, the width α _{j '} , 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.

For each 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 value n _βj = βj / T _β is, however, supplied to a monitoring device (in the simplest case a display DIS) via a multiplex switch in accordance with its assignment to the cylinder Zj.

 + Fj* 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 F * + F $\genfrac{}{}{0ex}{}{\text{*}}{\text{α}}$

+ Fj * controlled independently of the injection pumps of the other cylinders.

This and similar interventions stabilize the operation of the controller R and R _α .

Claims (13)

1. Method for regulating a slow-running multi-cylinder diesel engine, whereby

a1)   with each cylinder (Z1... Z2) there is associated an angular region (α; α₁... α₆), lying in front of its upper dead centre (t1, t2, t3...), from the cycle of the engine,

a2)   a first actual speed value (n) of the crankshaft, averaged by means of several of the angular regions (α; α₁... α₆), is formed, and

a3)   the first actual speed value (n) is compared with a first desired speed value (n*) and is supplied to a slow regulator (R), and whereby

b1)   angular positions (γ; γ₁... γ₆) of the crankshaft are established, which in each case correspond with the end angle (γ₁... γ₆) of the angular region (α; α₁... α₆) lying in front of the upper dead centre of the respective cylinder (Z1... Z6),

b2)   on reaching the respective angular position (γ₁... γ₆) a second actual speed value (n_α) of the crankshaft is formed, which corresponds with the average speed of the crankshaft in the respectively preceding angular region (α, α₁... α₆), and

b3)   the second actual speed value (n_α) is compared with a second desired speed value (n*) and is supplied to a fast regulator (R_α), and whereby

c1)   the output signal (F*) of the slow regulator (R) is used for the preadjustment of the filling ratios of all cylinders (Z1... Z6), and

c2)   the output signal (F_α*) of the fast regulator (R_α) is used for the adaptation of the preadjustment of the filling ratio for the respective cylinder (Z1... Z6).

2. Method according to claim 1, characterized in that the slow regulator (R) has substantially integral behaviour, the fast regulator (R_α) substantially proportional behaviour.

3. Method according to claim 1, characterized in that the angular regions (α, α₁... α₆) correspond at least approximately in each case with the angular distance of the crankshaft between the upper dead centres of the two adjacent cylinders (Z1... Z6).

4. Method according to claim 3, characterized in that the distance (d_α(n)) of an angular region (α₁... α₆) from the upper dead centre of the associated cylinder (Z1... Z6) is adjusted dependent on rotational speed (n).

5. Method according to claim 4, characterized in that with constant rotational speed (n) of the crankshaft the sum of the angular regions (α₁... α₆) results in the entire cycle of the engine, and in that to change the distance one of the angular regions (α₁... α₆) is temporarily changed.

6. Method according to claim 1, characterized in that in the comparison of the second actual speed value (n_α) with the second desired speed value (n*) deviations which lie beneath a specified threshold (DT) are suppressed.

7. Method according to claim 1, characterized in that the angular position (γ) of the crankshaft is continuously detected, the angular region (α, α₁... α₆) is specified through specification of an initial value and a final value (γ₁... γ₆; Pi), the time (T) between reaching the initial value and the final value is measured and from the measured time (T) the second actual speed value (n_α) is determined.

8. Method according to claim 1, characterized in that the first actual speed value (n) is determined by measuring the time required for an entire cycle of the engine in each case.

9. Method according to claim 1, characterized in that an average rotational speed (n_βj) associated with one of the cylinders is measured, with which the crankshaft passes through an angular region (β_j) beginning practically at the upper dead centre of this one of the cylinders (Z_j), in that the average rotational speed (n_βj) is compared with a desired value (n*) and the filling ratio of the cylinder (Z_j) associated with this speed (n_βj) is corrected thereby.

10. Device for regulating the rotational speed of a slow-running multi-cylinder diesel engine, having

a)   an angle transmitter (DET, CT), coupled to the crankshaft, which continuously detects the actual angular position (γ) of the crankshaft and on reaching specified reference angular positions (γ₁, γ₂,...) of the crankshaft in each case emits a reference pulse,

b)   means (CT1, M1, DIV1), attached to the angle transmitter (DET, CT), for the formation of a first averaged actual speed value (n), with which the crankshaft passes through more than two reference angular positions (γ₁, γ₂,...),

c)   means (CT2, M2, DIV2), attached to the angle transmitter (DET, CT), for the formation of a second averaged actual speed value (n_α), with which the crankshaft passes through an angular region (α₁... α₆) in each case given by two reference angular positions and lying in front of the upper dead centre of the respective cylinder,

d)   a slow regulator (R), supplied from the difference (n - n*) of the first actual speed value (n) with the first desired speed value (n*), which regulator produces a first regulating signal (F*),

e)   a fast regulator (R_α), supplied from the difference (n_α - n*) of the second actual speed value (n_α) with the second desired speed value (n*), which regulator produces a second regulating signal (F_α*), and

f)   means (P1,..., P4) for the control of the filling ratio of the individual cylinders in dependence upon the sum (AD) of the two regulating signals (F* + F_α*).

11. Device according to claim 10, characterized by means (FKT, ST) which adjust the position of the angular regions (α, α₁... α₆) relative to the upper dead centres of the cylinders (Z1... Z6) in a manner dependent on speed (n).

12. Device according to claim 11, characterized by a dead element (DT) for the suppression of small values of the difference (n_α - n*) of the second actual speed value (n_α) with the second desired speed value (n*) at the input of the fast regulator (R_α).

13. Device according to claim 11, characterized by means (CT3, DIV3) for the formation of a third mean value (n_βj) of the speed, with which the crankshaft, after passing through the upper dead centre (T_j) of a cylinder (Z_j), passes through a further angular region (β_j) associated with this cylinder, and means (F_j*) for changing the filling ratio of this cylinder (Z_j) in dependence upon this third mean value (n_βj) (Figures 4, 5).

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