WO2023036678A1

WO2023036678A1 - Method with a drive with an internal combustion engine and hydraulic power converters, and drive with an internal combustion engine and hydraulic power converters

Info

Publication number: WO2023036678A1
Application number: PCT/EP2022/074305
Authority: WO
Inventors: Botond Szeles; Sebastian Oschmann; Joerg Spang
Original assignee: Robert Bosch Gmbh
Priority date: 2021-09-13
Filing date: 2022-09-01
Publication date: 2023-03-16
Also published as: DE102021210068A1

Abstract

A method is disclosed with a drive (1) with an electronic control unit (3) and an internal combustion engine (2) which can be regulated thereby in accordance with an in particular predefined setpoint rotational speed, and with a hydraulic machine (4) which is coupled in terms of torque to said internal combustion engine (2) and via which at least one hydraulic power converter of the drive can be supplied with pressure medium, wherein a torque of the hydraulic machine can change in a manner which is dependent on a request directed at it and/or a request directed at the power converter, or in a manner which is dependent on a load in particular of the power converter, with the steps: "regulating of the rotational speed in a manner which is dependent on the setpoint rotational speed", via an electronic control unit of the drive, and "detecting of the request and/or load", via an electronic detection unit of the drive. In addition, a drive (1) is disclosed with an electronic control unit (3) and an internal combustion engine (2) which can be regulated thereby in accordance with a setpoint rotational speed, and with a hydraulic machine (4) which is coupled in terms of torque to said internal combustion engine (2) and via which at least one hydraulic power converter of the drive can be supplied with pressure medium, wherein a torque of the hydraulic machine can change in a manner which is dependent on a request directed at it and/or a request directed at the power converter, or changes in a manner which is dependent on a load in particular of the power converter.

Description

Method with a drive with an internal combustion engine and hydraulic power converters, and

Drive with an internal combustion engine and hydraulic power converters

Description

The invention relates to a method with a drive according to the preamble of patent claim 1 and a drive according to the preamble of patent claim 9.

A generic drive has a speed-controlled internal combustion engine and at least one hydraulic machine that can be driven by it and can therefore be operated in pump operation—referred to below as a hydraulic pump. From this, in turn, at least one hydraulic power converter, for example a hydraulic cylinder or a hydraulic machine that can be operated as a hydraulic motor, can be supplied with pressure medium. The drive can, for example, be in the form of a travel drive, work drive or combined travel and work drive, with the internal combustion engine often being in the form of a diesel engine, particularly in the field of mobile work machines. For example, traction motors or hydraulic cylinders of the mobile work machine, or both, can be supplied with pressure medium via the hydraulic pump.

Both the load of the power converter or converters and a request directed at them, for example with regard to a target speed or target acceleration, result in a target torque of the hydraulic pump coupled to the internal combustion engine. Likewise, a request directed directly at the hydraulic pump, for example the adjustment of its delivery volume, results in a target torque. The target torque of the hydraulic pump is to be provided by the internal combustion engine as an internal torque, with simultaneous regulation to a predetermined target speed. Current state-of-the-art Tier4 / Euro5 internal combustion engines (ICE) used in mobile work machines often do not offer an interface for direct torque control. Instead, an internal torque of the internal combustion engine follows as part of a speed control. If, for example, the load pressure in the hydraulic circuit increases due to an increased load on the power converter or a demand on it, the torque of the hydraulic pump increases. If the injection of the internal combustion engine is still the same, its actual speed falls below the predetermined target speed. Only when this control deviation is recorded and reported to the control unit is more fuel injected into the combustion system and the boost pressure and, as a result, the internal torque increase.

The disadvantage here is that the change in the internal torque first requires the control deviation of the speed before it can be increased or decreased by the increased injection. However, this occurs with a delay because, for example, manipulated variables in the hydraulic system react to the request with a delay. As a result, the internal torque follows the demand or load electronically recorded in real time. As a result, when the demand/load increases rapidly, the speed can be undesirably reduced and the internal combustion engine can stall. Conversely, an abrupt drop in load or demand can lead to an undesired overspeed of the internal combustion engine.

According to the prior art, the undesired pressure can be counteracted by limiting the power, in particular the torque, of the hydraulic machine and the power converter supplied with pressure medium by it.

In order to limit the power of such drives with an internal combustion engine as the primary power source, the prior art knows a purely speed-based limitation, with the actual speed of the internal combustion engine being compared with the target speed and based on the difference or ratio of the two, the manipulated variables of the power converters, respectively - buyers, are limited. A disadvantage of this solution is a tendency to oscillate, since such a pure regulation is carried out without any pilot control component.

Another solution uses the determination of a maximum possible torque of the internal combustion engine as a function of the setpoint speed, with this maximum possible torque being used as a reference variable for the power limitation of the power converter Z consumers.

The disadvantage is that the torque envelope curve used for the determination only applies to a steady to quasi-steady state of the internal combustion engine, but not to more dynamic load changes when the internal combustion engine is loaded relatively quickly, for example with low power consumption. Therefore, the reference to the aforementioned speed-based limitation is still necessary for power limitation.

A further possibility is the calculation of the currently theoretically maximum usable drive torque of the internal combustion engine, for example based on information from the internal combustion engine that is available by means of the network protocol SAE J1939 via the CAN bus. In particular, these are: the current percent torque, the reference torque and the percent load at the current speed.

Although this solution is also suitable for dynamic load changes, the signal quality of the information is often insufficient. This method can either not be used at all or only with additional and complex processing of the determined reference variable (limited torque). Special algorithms used here have proven to be partially unstable.

In contrast, the invention is based on the object of creating a method for controlling an internal combustion engine of a drive, which allows a shorter duration or level of the control deviation on the internal combustion engine when there are changes in the requirements or loads of the drive. In addition, there is Task is to create a drive that responds to changes in requirements or loads with a shorter duration or level of deviation of the internal combustion engine.

The first task is solved by a method with the features of patent claim 1, the second by a drive with the features of patent claim 9.

Advantageous developments of the invention are described in the respective dependent patent claims.

A method is provided with a drive, in particular with the drive of a mobile working machine. The drive has an electronic control unit and an internal combustion engine that can be controlled via this as a function of a particularly predetermined setpoint speed. The internal combustion engine is designed as a diesel engine, for example. At least one hydraulic machine, hereinafter referred to as hydraulic pump, is torque-coupled to this, via which at least one hydraulic power converter of the drive can be supplied with pressure medium in the open or closed hydraulic circuit. The at least one hydraulic pump can be designed with a constant or adjustable displacement volume. The at least one power converter can be designed in a translatory manner—for example as a hydraulic cylinder—or in a rotary manner—for example as a hydraulic machine, in particular a hydraulic motor. It too can be designed with a constant or adjustable displacement volume. The hydraulic pump, the hydraulic motor can be designed, for example, as an axial piston machine with a swash plate or bent axis design. A torque of the hydraulic machine can change depending on a request directed at the hydraulic machine - for example a request signal that results in an adjustment of its displacement volume - or the torque changes depending on a request directed at the power converter or because its load changes. In order to maintain a target speed of the internal combustion engine, in particular a predetermined one, despite possible changes in the requirement(s) or load(s), the method has a step of "regulating the speed in Dependence on the target speed”, via the electronic control unit. In addition, there is a step “detection of the request and/or the load”, in particular via an electronic detection unit of the drive.

According to the invention, the method has a step “determining a target deviation of the speed from the target speed”. The target deviation is determined as a function of the electronically recorded requirement(s) and/or load(s) (hereinafter, for reasons of clarity, requirement/load).

In other words, a new, preferably temporary, target speed that deviates from the predetermined target speed is determined, which then goes into controlling the speed. According to the invention, use is made of the fact that in the generic drive between the electronic detection of the request/load and the detection of the resulting speed change (depression with increasing request/load, overspeeding with decreasing request/load) there can be a dead time, which results in the sluggish behavior of hydraulic actuators is justified. Due to the setpoint speed changed according to the invention in real time with the detected requirement/load and the associated modified injection, the internal torque of the internal combustion engine is prepared earlier for the detected and thus upcoming requirement/load by a period of time corresponding to the dead time. Thus, according to the invention, the duration of the control deviation and its amount can be influenced.

In a further development, the setpoint deviation is determined in such a way that the amount and/or duration of a control deviation that occurs when the speed is controlled as a function of the sum of the setpoint speed and the setpoint deviation is/are less than if the speed is controlled as a function of the setpoint speed alone - i.e. without setpoint deviation. In this way, the duration of the control deviation and its amount can be reduced in an even more targeted manner.

The setpoint deviation is preferably determined with a sign and has, for example, a positive sign when the requirement/load increases, whereas it has a negative sign when the requirement/load falls. The sum of the target speed and the target deviation is therefore greater than the predetermined target speed when the requirement/load increases. Thus, the speed depression caused by the load or demand is mitigated and its duration is reduced. On the other hand, if the requirement/load falls, the sum of the setpoint speed and setpoint deviation is less than the predetermined setpoint speed. In this way, the speed over-revving caused by the decreasing load or demand is mitigated and its duration is reduced.

The demand on the hydraulic machine can be, for example, a target displacement volume, a target pressure medium volume flow or a target torque. The request to the power converter or converters can be a respective target speed, a target acceleration or a target torque. Wherein the load is a mass to be held, a mass to be accelerated, a change in a driving surface such as a change in inclination, or a load pressure, or the like.

In order to prevent the influence of signal noise and a target deviation that is incorrectly or unnecessarily determined based thereon, the method has a step “filtering a request signal and/or load signal” in a further development.

In a further development of the method, the new, preferably temporary target speed is included in the regulation by a step “overriding the predetermined target speed with the sum of the predetermined target speed and target deviation”.

The predetermined set speed must not be overridden in the event of an oscillating demand or load signal or if the changes in the demand or load signal are too small. A measure of a possible oscillation is a comparatively steep rise and fall of the detected signal, in particular when the amplitude or deflection of the respective signal is comparatively small at the same time. In a further development of the method, a step "determining a deflection and/or a gradient of the requirement and/or load, or of the respective signal”. For the reasons mentioned, this determination is also preferably carried out on the basis of the filtered signal(s) of the request and/or load.

Based on this, according to a development of the method, a step “comparing the deflection and/or the gradient of the requirement and/or load with a respective reference” can take place. The reference for the gradient is preferably stored in the electronic control unit as a rate of increase parameter, each individually for a positive deflection and for a negative deflection, in a predetermined manner and can preferably be set individually, for example for a particular machine type.

If the deflection detected is smaller than its reference and/or the gradient is steeper than its reference, it is assumed that the signal in question is oscillating and at least one of the steps “waiver of determination of the target deviation”, “suppression of the Oversteering", "setting the target deviation to zero" or "regulating the speed solely as a function of the predetermined target speed" or the like is carried out.

If, on the other hand, the deflection is greater and/or the gradient is flatter than the relevant reference, it can be assumed that there is no oscillating signal. The aforementioned step "overriding the target speed with the sum of the target speed and the target deviation" is then carried out.

Not only the target deviation, but also its development over time influences the control deviation and its duration. In a further development of the method, a step “determining the setpoint deviation and/or its gradient as a function of the deflection and/or the gradient of the requirement and/or load” therefore takes place.

In a development of the method, the setpoint deviation can be limited via the control device, preferably by means of saturation, so that excessive deviations in the actual speed can be avoided, which the operating personnel can perceive as a disruptive overspeed or underspeed. In order to avoid excessively high totals from the predetermined speed and the target deviation determined as a function of the requirement and load, which are based on requirements that cannot be realized, in particular target torque requirements, the method has a step in a further development: “determining a minimum from an available power, in particular an available torque of the internal combustion engine and the performance, in particular torque requirement”. The step “determining the target deviation from the particularly predetermined target speed” then takes place as a function of the determined minimum.

If the requirement is a target power or a target torque, a limitation can be carried out by a step “Limiting the power requirement or torque requirement by limiting the target torque to a limit torque”. The limit torque can preferably be determined on the basis of a model.

For this purpose, in one development, at least one static or dynamic or at least partially dynamic model of the internal combustion engine is set up in the control unit, via which a target torque currently requested for the at least one hydraulic machine or the at least one power converter can be limited to a limit torque. The setpoint torque can be requested, for example, by an operator, for example by deflecting an operating element of the drive (joystick), or by a machine controller.

The model can have a dynamic partial model of the internal combustion engine, via which the internal torque that can be provided by the internal combustion engine at a future point in time, i.e. a minimally later than the current point in time, can be determined at least as a function of the actual speed and the load on the internal combustion engine. The specified limit torque can then in turn be determined as a function of this.

This model-based depiction of the dynamic development of the internal torque of the internal combustion engine ensures the utilization of the maximum possible power at the desired target speed, without undesired ones RPM dips. This is particularly advantageous for the above-mentioned diesel engines from Tier 4 interim upwards, as these often have only a small torque reserve and strict specifications regarding the permitted speed reduction, which means that precise and stable power limitation of the hydraulic machine and/or the power converter or power consumer is required .

In one development, the limit torque can be determined via the control unit as a reference variable for limiting the power consumption of the hydraulic machine or of the power converter(s). Alternatively, such a command variable can be determined from the limit torque via the control unit. In particular, this is the case when several hydraulic machines are driven or several power converters are supplied with pressure medium by the hydraulic machine or machines. The limit torque determined must then first be “distributed” to the hydraulic machines and/or power converters via the control unit, i.e. an individual limit torque is determined for each hydraulic machine or per power converter. Depending on the respective command variable, the respective hydraulic machine/the respective power converter can then be controlled, in particular pilot-controlled, in order to limit its power consumption. A control of the power consumption of the relevant hydraulic machine/the relevant power converter can be minimized or even superfluous by such a pre-control.

For the specific control of the relevant hydraulic machine/the relevant power converter, in one development, a setpoint value of a manipulated variable of the relevant hydraulic machine/the relevant power converter can be determined via the control unit, on which its torque depends. In the case of a volume-adjustable hydraulic machine or a power converter designed in this way, such a manipulated variable is, for example, the displacement volume.

In a further development, the control unit has a first static, stationary or quasi-stationary partial model, in particular a characteristic map, via which a first currently maximum permitted torque can be determined, in particular as a function of at least the current speed and load, in particular the current internal torque of the internal combustion engine. In a further development, the torque that can be provided in the future can be determined via the dynamic partial model as a function of the first currently maximum permitted torque.

In a preferred development, the torque that can be provided in the future can be determined via the dynamic partial model as a function of the first currently maximum permitted torque by means of a delay element of the nth order, in particular of the second order. Dynamic ramp limitation is preferably provided.

Preferably, input signals of the respective models are preceded by smoothing, in particular a filter, in particular with a PT-1 characteristic.

In one development, the dynamic sub-model has at least one input that can be updated periodically or recurringly via the control unit, it being possible to determine the torque that can be provided in the future, in particular at the same interval, so that it can be updated. The first currently maximum permitted torque is preferably present at this input.

In a preferred development, the first currently maximum permitted torque can be updated periodically or recurringly via the control unit, preferably with the same period or at the same update times as the input of the dynamic partial model.

In a further development, the mentioned delay is changeable or variable, in particular from a current point in time to a future point in time or from one update to the next.

In one development, the model has a second static partial model of a second currently maximum permitted torque of the internal combustion engine as a function of a current temperature, a third static partial model, in particular a torque envelope, of a third maximum permitted Torque of the internal combustion engine depending on the current speed, and / or a reference torque of the internal combustion engine, depending on which or which the future torque can be limited to the limit torque.

In a development, a currently theoretically maximum usable drive torque of the internal combustion engine can be determined via the control unit as a function of information from the internal combustion engine that can be made available in particular via CAN bus/J1939.

In one development, a combination device is provided, via which a hybrid torque can be determined as a function of the limited or unlimited torque that can be provided in the future and the currently theoretically maximum usable drive torque.

In one development, a selection device is provided, via which the limited or unlimited torque that can be provided in the future, the currently theoretically maximum usable drive torque and the hybrid torque can be individually selected, with the limit torque being able to be determined depending on the selection.

In one development, a summation device is provided, via which a sum can be formed from the selection and a requestable or deliverable torque of at least one secondary power converter and/or a torque of a flywheel mass model of the internal combustion engine.

In a further development, an overload protection device is provided for the internal combustion engine, via which the limit torque can be reduced to a reduced limit torque in such a way that the permissible pressure is not reached.

Preferably, the overload protection device has a PI controller and the permissible pressure of the internal combustion engine is in each case separately for a P Controller portion and for an I controller portion of the PI controller, depending on a target speed of the internal combustion engine available.

In a further development, the PI controller can be activated or deactivated depending on the current load, in particular the current torque of the internal combustion engine, so that an initial load on the internal combustion engine is possible and the power converters and consumers can be accelerated as dynamically as possible.

In one development, an I controller component of the PI controller has control parameters that are dependent on a gradient of the current speed or that can be set. Depending on the direction of speed change, the different control parameters enable a reduction of the target torque without oscillations, with continuous, maximum possible load on the internal combustion engine.

In one development, the overload protection device can be deactivated or inactive at an idle speed and can be activated or active above a current target speed.

A drive for a mobile working machine has an electronic control unit and an internal combustion engine that can be controlled by this according to a target speed and a hydraulic machine torque-coupled to this, via which at least one hydraulic power converter of the drive can be supplied with pressure medium. A torque of the hydraulic machine can be changed as a function of a request directed at it and/or a request directed at the power converter or changes as a function of a load, in particular of the power converter. In this case, a method, which is designed according to at least one aspect of the preceding description, is stored in the control unit for execution. The control unit is designed according to the invention in such a way that a target deviation of the speed from a target speed stored in a predetermined manner in the control unit as a function of the electronically recorded requirement and/or load can be determined in such a way that an amount and/or a duration of a control deviation when controlling the speed depending on a sum of the predetermined setpoint Speed and the target deviation is lower or are than when controlling the speed solely as a function of the predetermined target speed.

In the following, one exemplary embodiment of a method and drive according to the invention is explained in more detail in drawings. Show it:

Figure 1 shows a drive according to an embodiment,

Figure 2 shows a method for controlling the drive according to Figure 1, according to an embodiment,

FIG. 3 shows a greatly simplified block diagram of a variant of the drive according to FIG.

FIG. 4 shows a schematic of a control unit of the drive according to FIG. 1,

Figure 5 shows a diagram of a model stored in the control unit for determining a torque limit of the internal combustion engine as a reference variable for the driven hydraulic machine or the power converters supplied with pressure medium, Figure 6 a static input model of the dynamic model according to Figure 3, Figure 7 a diagram of one that can be provided by the internal combustion engine in the future Torque depending on a currently permitted torque of the internal combustion engine,

FIG. 8 a combination logic for calculating static and dynamic partial models,

Figure 9 is a schematic of an overload protection device of the internal combustion engine, and

FIG. 10 shows a diagram with time-dependent curves of operating variables of the internal combustion engine and a power converter designed as a hydraulic pump, with and without oversteering the setpoint speed.

According to Figure 1, a drive 1 has an internal combustion engine 2 and a hydraulic power converter 4 driven by it and designed as a hydraulic machine with an adjustable displacement volume hydraulic circuit from a tank T can be supplied with pressure medium. Alternatively, the hydraulic circuit can be closed. The internal combustion engine 2 is, for example, a Prime mover of a mobile work machine (not shown) and configured as a diesel engine. The drive shaft of the hydraulic machine 4 is torque-coupled to its drive shaft. In the case of the mobile working machine, the hydraulic machine 4 preferably works in pump operation in order to drive the power converters—hydraulic cylinders or motors—by means of a pressure medium volume flow. Motor operation of the hydraulic machine 4 is also possible, for example when the load on the supplied power converters is reversed, so that recuperation of pressure medium energy is possible. The power converter is supplied with pressure medium via a respective control valve (not shown), preferably via an LS or LUDV control.

The internal combustion engine 2 is assigned a control unit 3, which is signal-connected to a control unit 8, which is assigned to the hydraulic machine 4 and the power converter (not shown). An injection of the fuel is controlled via the control unit as a function of a setpoint speed nNsoii stored in a predetermined manner.

The fuel is injected as part of the regulation of the speed n of the internal combustion engine 2 as a function of the predetermined setpoint speed nNsoii, the detected actual speed nist and according to the invention as a function of the detected or determined load of the at least one power converter, the detected or determined demand on the at least one power converter and/or the recorded or determined requirement for the at least one hydraulic machine 4. The latter is recorded in the drive, in particular via a recording unit 7 designed as a joystick in the exemplary embodiment.

FIG. 2 shows a method according to the invention according to an exemplary embodiment, the mode of operation of which is explained below by looking at it together with the drive according to FIG. 1 and the diagram according to FIG.

Step 100 “detection of the requirement M _so ii” takes place continuously. In the exemplary embodiment, the request results from a deflection of the joystick 7 according to FIG. This deflection is via the control unit 8 as a movement request to one of the hydraulic machine 4 with pressure medium Supplied hydraulic power converter or interpreted at one of the power converter or moving working point (TCP) of the machine. The deflection can, for example, result in the requirement for the hydraulic machine 4 to increase the pressure medium volume flow for supplying pressure medium to the at least one hydraulic power converter by increasing its delivery volume by pivoting out. The torque of the hydraulic machine increases to a target torque M _so ii in proportion to the increased delivery volume. The latter represents the requirement at the level of the internal combustion engine 2 and must be provided by it. In addition, the load is continuously detected by a pressure detection unit (not shown) of the drive 1 .

Step 102 “filtering the request Msoii, in particular the request signal” also takes place continuously in the method according to the invention as shown in FIG. In this way, the influence of signal noise and a setpoint deviation that is incorrectly or unnecessarily determined based thereon is eliminated.

In the following step 104, the filtered request signal Msoii is examined for its deflection AMsoii and/or its rate of rise, ie its time gradient dM _SOii /dt.

The determined deflection AMsoii and/or the gradient dM _SOii /dt are then compared in step 106 with a respective reference AMR _SOII and/or dMpsoii/dt, with the aim of preventing the determination of a setpoint deviation if the request signal is oscillating is based on a disturbance rather than on a real requirement. If the deflection AMsoii is smaller than its reference AMR _SOII and the gradient _dMSOii /dt is steeper than its reference _dMRSOii /dt, an oscillating signal is assumed and no setpoint deviation is subsequently determined. Instead, the speed control continues to take place solely as a function of the predetermined speed nNsoii according to step 108.

Conversely, if the deflection AMsoii is greater than its reference AMR _SO II and at the same time the gradient dM _SO ii / dt is flatter than its reference dMR _SO ii / dt, according to step 110, a setpoint deviation ± AnTsoii to the setpoint speed nNsoii dependent on the electronically recorded requirement M _so ii are determined. According to the invention, this determination is made in such a way that the amount and duration of a control deviation when controlling the speed n as a function of a sum of the predetermined setpoint speed nNsoii and the determined setpoint deviation ±AnTsoii are lower than with conventional control of the speed n as a function only the setpoint speed nNsoii.

Based on the determined setpoint deviation ±AnTsoii, in step 112 the predetermined setpoint speed nNsoii is overridden with the sum of the predetermined setpoint speed nNsoii and the setpoint deviation ±AnTsoii. The sum then represents the temporary, new target speed n _S oir.

The speed n is then controlled in step 108', still as a function of the predetermined speed nNsoii, which, however, according to the invention is changed by the desired deviation ±AnTsoii.

FIG. 10 on the left shows the course of the current speed n _a kt or actual speed nact as a function of the request signal Msoii with a conventionally constant desired speed _nsoii .

Figure 10 on the right, on the other hand, shows the course of the current speed n _a kt or actual speed nact as a function of the request signal Msoii with the setpoint speed n _so ii 'overridden according to the invention, i.e. when using the method according to the invention according to Figure 2 from step 110.

The aim of the described target speed override is to reduce the reaction time of the internal combustion engine 2 by preparing it for the upcoming increasing or decreasing load by overriding the target speed nNsoii stored in a predetermined manner in the control unit 3 with the target deviation ±An _SO ii becomes. In particular, Tier4/Euro5 Internal Combustion Engines (ICE) only increase their internal torque when an RPM deviation occurs. When the requirement or load increases, the actual or current speed nact or n _a kt falls below the predetermined desired speed nNsoii while the injection remains the same. As a result, more fuel is injected into the combustion via the control and the boost pressure and thus the internal torque is increased, which in turn leads to the control deviation of the speed being corrected. Provoking this rotational speed deviation by loading the internal combustion engine 2 through the power consumption of the hydraulic machine 4 (pivoting out the swivel angle a of the power converter 4 designed as a hydraulic pump) leads to the conventional procedure - i.e. if the predetermined setpoint rotational speed nNsoii is not overridden - compared to the request or the requirement jump M _so ii delayed provision of power Lakt (see FIG. 10 left).

In order to reduce or avoid this delay, a positive target deviation +An depending on the requirement jump M _so ii is determined using the method according to FIG is added to the predetermined setpoint speed nNsoii.

The setpoint speed override device can, of course, be located in another control unit of the drive, for example in control unit 8, instead of in the control unit of the internal combustion engine.

According to the invention, the setpoint speed n _S0 n is increased beyond its normal/predetermined operating value nNsoii (conventional horizontal line in FIG. 10 left vs. peak in FIG. 10 right). This takes place even before the driven hydraulic pump 4 responds to the jump in demand Msoii by swiveling out and thus increasing its swivel angle α and delivery volume, or another component in the drive 1 begins to increase its power consumption from the internal combustion engine 2 .

In the exemplary embodiment, the amount of the positive target deviation +An is dependent on the magnitude of the step in the requirement, ie the magnitude of the requested torque Msoii (first derivation of the total torque requirement of the hydraulic machine 4 driven directly by the internal combustion engine 2). The positive target deviation +An is determined and added to the predetermined target speed ANSOII. The predetermined desired speed riNsoii is temporarily overridden with the new desired speed risoir determined in this way.

In order to avoid a setpoint deviation +An, which is based on a requirement that cannot be realized or a requirement jump that cannot be realized, a minimum of the available torque of the internal combustion engine 2 and the requested torque M _so ii can be selected.

If the torque requirement is greater than the available torque, a volume flow requirement directed to the hydraulic machines 4 can be applied to the limit torque MMCII Grenz or MMCII described in Figures 4 to 9, in particular via the control unit 8, in particular via the power manager 20 Limit red can be limited as a reference variable.

In order to ensure a stable, positive setpoint deviation +An, the request coming into the setpoint speed override device 18 can be filtered.

In order to ensure that the function can be adapted to other internal combustion engines with different dynamics of an air charging system, a scaling factor is preferably provided as a P component.

FIG. 3 shows a simplified block diagram of the drive 1, several hydraulic machines 4, 6 now being driven by the internal combustion engine 2, that is to say being torque-coupled to it. The drive power of the internal combustion engine 2 can be transferred to the drive shafts of the hydraulic machines 4, 6 via a power manager of the drive 1, particularly in the event of undersupply, when the power required or requested by the hydraulic machines 4, 6 to supply their power converters cannot be completely covered by the internal combustion engine 2 be distributed. For this purpose, a control unit 8 is signal-connected both to the internal combustion engine 2 and to the hydraulic machines 4 , 6 via a CAN bus 10 . FIG. 4 shows a more detailed diagram of the control unit 8 according to FIG. 1, which is connected to the CAN bus 10 on the one hand and to further machine control functions 12 on the other hand. In order to avoid overloading and in particular to prevent the internal combustion engine 2 from "stalling" when the power consumption or demand of the power converters 4, 6 increases sharply, a torque determination device 14 for the model-based determination of a limit torque MMCII Grenz that can be provided by the internal combustion engine 2 is included.

According to FIG. 2, the limit torque MMCII Grenz goes into an overload protection device 16, which is optional in the exemplary embodiment shown, and can be further reduced there to a reduced limit torque MMCII Grenzred, so that the permissible speed reduction Aniim remains even more reliably undershot.

The control unit 8 has a power manager 20 in order to distribute the reduced limit torque MMÜI Grenz red determined by means of the torque determination device 14 and the overload protection device 16 to the power users 4 , 6 . Without the aforementioned, optional overload protection device 16, the power manager 20 would have the limit torque MMCII limit as an input variable.

FIG. 3 shows the structure of the torque determination device 14 in detail. Inputs are at least the current values of the speed n _a kt, the torque Makt and the operating temperature cycle of the internal combustion engine 2, as well as the current percentage torque Makt, reference torque _Mpe f and provided by the CAN bus 10 in accordance with the network protocol SAE J193 the percent load at the current speed lact. The Makt and Lakt inputs are smoothed by filters 20, 22, 24, each designed as a PT-1 element in the exemplary embodiment.

On the input side, the torque determination device 14 has two sections or partial models 26, 28. According to FIG. 3, a first partial model 26 is used to calculate the currently theoretically maximum usable drive torque Makt th max nutz, based on the aforementioned, using the SAE J1939 network protocol via the CAN bus 10 The second partial model 28 is used for the dynamic, model-based determination of a torque MMCII for a minimum, approx. 50-400 msec, later point in time as a function of the current values n _a kt, Makt, Takt. The current torque Makt, taken alone or together with the current speed n _a kt, represents a measure of the current load on internal combustion engine 2.

In the exemplary embodiment according to FIG. 3, the two outputs Makt th max nutz and MMCII of sections 26, 28 enter an optionally provided combination device 30 according to FIG. 6, via which a “hybrid torque” Mhyb can be determined from the two. In particular, a ramp function of the air system is included in its determination. The input signals Makt th max nutz and MMCII each pass through a filter, in particular PT-1 filter 38, 40, and as a result a derivative 42, 44. The derivative 44 of the input signal MMCII is determined by means of a greater than or equal comparison with a minimum Compared gradient dMMdi min of the input signal MMCII. The derivative 42 of the input signal Makt th max nutz is compared with a minimum gradient dMnutz min of the input signal Makt th max nutz by means of a greater than or equal comparison and with its maximum gradient dMnutz max by means of a less than or equal comparison.

According to FIG. 6, the results of the two last-mentioned comparisons are combined with an AND operation and enter into an OR operation with the result of the first-mentioned comparison. In parallel with this, the smaller of the two torques Makt th max nutz and MMCII is determined by the combination device 30 . A switch 46 can be used to select the smaller of the two torques Makt th max nutz and MMCII or the available torque MMCII determined on the basis of the model, the gradient resulting from the OR link being applied to the selection. The latter selection is then included in a ramp function 48, the output of which finally forms the hybrid torque Mhyb.

The available torque MMCII of the partial model 28 according to FIG. 3, determined on the basis of a model, is a stable signal in all operating states of the drive 1. For the cases lower and on the other hand higher and maximum A variable parameter setting of the PT2 characteristic of the dynamic partial model 18 is also provided for the signal change frequency. Due to differences between the ideal properties of this model and real conditions of an ICE air system of the internal combustion engine 2, such as air volume and temperature, especially in the turbo, the load on the internal combustion engine 2 may be higher than the ICE can handle. In this case, the CAN-based calculation according to the partial model 26 will deliver a lower value Maktth max nutz than the model-based signal MMCII according to the partial model 28. The former also proves to be stable because an operating state of the internal combustion engine 2 does not change as quickly under load changes, as this would affect the speed of the internal combustion engine 2 negatively. In this case, the CAN-based signal Makt th max nutz is sufficient as a basis for a pilot control carried out with it. In other cases, when the internal combustion engine 2 has a certain reserve, the CAN-based calculation of Makt th max use can result in rapidly changing feedforward signals that would negatively affect the speed of the internal combustion engine 2 .

In order to be able to react flexibly to these different starting conditions, the two torques Makt th max nutz and MMCII, as well as the hybrid torque Mhyb formed therefrom via the combination device 30 according to FIG. In this case, the smallest of the three torques Makt th max nutz, MMCII and Mhyb is preferably selected. The selection is preferably automated. Alternatively or additionally, other selection criteria can be provided, in particular as a function of state variables of the drive 1 that can be provided by the CAN bus 10 .

If the torque MMCII determined based on the model is selected in the selection device 32 in an acceleration phase of the power converters 4, 6, a certain torque reserve results in the ICE. This is intentional, since a stable and even movement speed with maximum possible dynamics is more important than maximum power consumption. The torque selected in the selection device 32, whether it is Makt th max nutz, MMCII or Mttyb, goes into an optional summation device 34 in the exemplary embodiment according to FIG Flywheel mass model of the internal combustion engine 2 calculated torque are taken into account to finally calculate the model-based limit torque MMCII limit.

FIG. 4 shows a map valid for stationary operating states of a first currently maximum permitted torque MMCII stat akt max 1 as a function of the current speed n _a kt and the current torque Makt (dimensionless) transmitted according to J1939. The first currently maximum permitted MMCII stat act max 1 torque determined from the characteristics map is entered into the dynamic sub-model 18, from which the torque MMCII dyn that can be provided in the future is calculated by means of a ramp limitation and a second-order delay. The term “in the future” is based in particular on the positioning times of the power converters 4, 6, which are in particular in the range from about 50 to 400 msec.

The diagram according to FIG for the power converters 4, 6 requested setpoint torque Maktsoii entered in the diagram. However, the torque MMdi dyn that can be provided in the future is calculated independently of this.

At a point in time ti, the first currently permitted torque MMdi stat akt max i, ti is determined as a function of the current speed n _a kt and the current load state Makt in accordance with J1939/SPN513 using the characteristics map stored in control unit 8 according to FIG.

The torque MMdi stat akt max i, ti represents the input into the dynamic sub-model 18 at the time ti. Using its PT-2 characteristic and a ramp limitation, the time profile of the future is dependent on the input signal MMdi stat akt max 1 available torque MMCII dyn, n determined for times after ti. It is easy to see that the torque MI I dyn,ti that can be provided in the future is the first currently permitted torque MMdistataktmaxi. ti approaches with a PT-2 characteristic and is therefore smaller than the first currently permitted torque MMdistataktmaxi for all points in time before this approach. ti. At time t2, the input signal MMdistataktmaxi, t2 and, depending on this, the torque Mividi dyn, t2, which can be provided in the future, are recalculated on the basis of updated values of the current speed n _a kt and the current load state Makt in accordance with J1939/SPN513, and so on. Over time (ti to t _n ) the course Mivididyn results overall.

This periodically updated determination takes place at predetermined time intervals At _caic stored in control unit 8 so that the model-based torque limit MI I dyn can be calculated based on the information from internal combustion engine 2 that is always recorded and transmitted via CAN bus 10 . The larger the time intervals At _ca ic are selected, the more stair-stepped the resulting Mivididyn characteristic curve becomes. The more frequently the update takes place, that is to say the smaller the time intervals At _ca ic are and the more frequently new information is available, the smoother the resulting Mivididyn characteristic curve.

According to Figure 3, the calculated torque MMdidyn that can be provided in the future can also optionally be changed, in particular further limited, by further static models Mividistat akts (speed-dependent torque envelope), kmdi statakt2 (temperature-dependent torque factor) and/or a reference torque Mp _e f of the internal combustion engine 2 , before it enters the combination device 30 and the selection device 32, as described above.

FIG. 7 shows the structure of the overload protection device 16 according to the exemplary embodiment. It is based on the logic of a PI controller, via which the limit torque MI I Grenz determined by the torque determination device 14 according to the previous description can be reduced in such a way that an impermissible negative speed change of the internal combustion engine 2 is avoided. The overload protection device 16 shown in FIG. 7 has the following functionalities: - For the state in which the setpoint speed n _S0 n is to be increased from an idle speed ("idle") back to the operating speed if, for example, operating personnel want to operate drive 1 again after a break: through the ramp limitation dn _S oii iim the setpoint speed n _S0 n when the speed n increases, the function intervenes only after the operating speed has been set;

- Permitted speed reductions Anlim, which are dependent on the setpoint speed and the I controller component, are each determined separately for the P and I controller components;

- An activation of the respective controller component dependent on the current torque Makt (J1939/SPN513, "Actual Engine Percent Torque"), so that an initial load on the internal combustion engine 2 is permitted in order to be able to dynamically accelerate the power converter;

- The I controller has different I components/parameters, depending on the sign or direction of the speed change, in order to reduce the limit torque MMCII Grenz to the reduced limit torque MMCII Grenz red without oscillations but with continuous and maximum possible load of the internal combustion engine 2 to ensure.

The control unit 8 in its comprehensive configuration according to the invention combines different partial models in order to cover both the dynamic and the static or stationary loading and unloading state of the internal combustion engine 2 . In addition, the included control unit of the internal combustion engine 2 has the method according to the invention for overriding the predetermined setpoint speed. On the one hand, a stable and constant limitation of the hydraulic machines, power converters and consumers can be ensured by providing a reference variable for the power limitation, in particular the limit torque MMCII limit or MMCII limit red, in such a way that regulation in the course of the power limitation is largely dispensed with can be. On the other hand, the duration and amount of the control deviation of the speed is limited to a minimum by the described overriding of the setpoint speed.

Claims

25

Method with a drive, in particular that of a mobile work machine, with an internal combustion engine (2) that can be regulated according to a predetermined setpoint speed (nNsoii) and a hydraulic machine (4) torque-coupled thereto, via which at least one hydraulic power converter of the drive can be supplied with pressure medium , wherein a torque (M _so ii) of the hydraulic machine can be changed as a function of a request directed at it and/or a request directed at the power converter or changes as a function of a load, with steps

"(108, 108') Controlling the speed (n) depending on the predetermined target speed (nNsoii)", and

"(100) Capture the request (Msoii) and/or load", identified by a step

"(110) Determining a setpoint deviation (±AnTsoii) from the predetermined setpoint speed (nNsoii) as a function of the electronically recorded request (Msoii) and/or load". The method of claim 1, wherein the target deviation (± AnTsoii) is determined such that an amount and / or a duration of a deviation when controlling the speed (n) depending on a sum of the predetermined target speed (nNsoii) and the target deviation (± AnTsoii) is lower or are than when controlling the speed (n) depending solely on the predetermined target speed (nN target) ■ Method according to claim 1 or 2 with a step “(102) filtering a detected signal of demand and/or load”. A method according to any one of claims 1 to 3 comprising one step "(112) Overriding the predetermined setpoint speed (nNsoii) with a sum of the predetermined setpoint speed (nNsoii) and setpoint deviation (±AnTsoii)". A method according to any one of the preceding claims comprising one step

"(104) Determination of a deflection (AMsoii) and/or a gradient (dM _SO ii/dt) of the requirement (M _so ii) and/or load". A method according to claim 5 comprising one step

"(106) Comparing the deflection (AMsoii) and/or the gradient (dM _SO ii/dt) of the demand (Msoii) and/or load with a respective reference (AMRSOII, dMRsoii/dt)". and if the displacement (AMsoii) is smaller than its reference (AMR _SO II) and/or the gradient (dM _SO ii/dt) is steeper than its reference (dMR _S oii/dt), at least one of the steps

"Doing without determining the setpoint deviation" or "Suppressing oversteer" or "Setting the setpoint deviation (±AnTsoii) to zero" or "(108) Regulating the speed (n) solely as a function of the predetermined setpoint speed ( nNsoii)” or something like that. A method according to claim 5 or 6 comprising one step

"Determining the target deviation (±AnTsoii) and/or its gradient (dAnTsoii/dt) as a function of the deflection (AMsoii) and/or the gradient (dM _SO ii/dt) of the requirement (Msoii) and/or load". A method as claimed in any preceding claim, wherein the request is torque, having a step "Determining a minimum of an available torque (Mth) of the internal combustion engine (2) and the torque request (Msoii)", wherein the step

"Determining the setpoint deviation (±AnTsoii) from the predetermined setpoint speed (nNsoii)" then takes place as a function of the minimum. Method according to one of the preceding claims, wherein the request is a torque request (M _S0 n), with one step

- Limiting the torque requirement (M _S0 n) to a limit torque (MMCII limit, MMCII limit red). Drive, in particular for a mobile work machine, with an electronic control unit (3) and an internal combustion engine (2) that can be controlled by this as a function of a predetermined target speed (nNsoii) and a hydraulic machine (4) torque-coupled thereto, via the at least one hydraulic power converter of the drive can be supplied with pressure medium, in which case a torque of the hydraulic machine (4) can be changed as a function of a request directed at it and/or a request directed at the power converter or changes as a function of a load, in particular of the power converter, characterized in that via the Control unit (3) a target deviation (± AnTsoii) to the predetermined target speed (nNsoii) as a function of the electronically recorded request (M _S0 n) and / or load can be determined.