EP2746212B1 - Method for tracking the rotational speed of a crane drive and crane drive - Google Patents

Description

The invention relates to a method for speed tracking of a hydraulic crane drive with at least one hydraulic consumer, for example a hydraulic motor which is fed via at least one adjustable hydraulic pump, and which is driven by the drive unit of the crane at least one variable.

Cranes, in particular mobile cranes, have a hydraulic system for driving the various crane functions. This hydraulic system is supplied by one or more hydraulic pumps, which are supplied at least partially via a central drive unit of the crane, in particular an internal combustion engine. The delivery volume of the individual hydraulic pumps depends on the input speed of the engine output. The larger the volume pumped, the faster the speed of movement of each hydraulic consumer powered by the pump to perform different crane functions.

Usually, the driver of the crane does not know the required engine speed necessary for the proper operation of the crane hydraulics with the desired speed of movement necessary is. Due to this ignorance, the drivers run the drive unit at high speed to ensure sufficient reserves for setting any movement speed. In many cases, however, a much lower speed is sufficient. In addition to excessive fuel consumption and high noise emission, this also leads to unnecessarily heavy wear on the drive unit.

From the US Pat. No. 6,308,516 B1 a control device for hydraulically operated devices is known in which an engine is regulated in dependence on an engine speed parameter and a high-frequency component of a pump signal.

Object of the present invention is therefore to optimize the fuel consumption of the crane while reducing noise emissions.

This object is achieved by a method according to the features of claim 1. Advantageous embodiments of the method are the subject of the dependent subclaims.

According to claim 1, therefore, a method for speed tracking of a hydraulic crane drive is proposed. The hydraulic crane drive consists of at least one hydraulic consumer, in particular a hydraulic motor, for carrying out a specific crane function. At least one consumer serves, for example, as a rotary drive of the superstructure or to drive a winch. Furthermore, at least one hydraulic variable-displacement pump is provided, which supplies the at least one hydraulic consumer with an adjustable volume flow. The at least one variable displacement pump is driven by at least one central drive unit of the crane.

To realize a speed tracking, it is now provided according to the invention that the speed of the drive unit and the pivot angle of the at least one variable in dependence on the requested volume flow for at least one of the consumers and in dependence of another crane-specific Parameters are controlled or regulated by the crane control and that the target speed is calculated by the crane control from the requested volume flow. The calculation is carried out dynamically at runtime as a function of the current requested volume flow.

The influence of the crane control on the speed tracking can also be overridden at any time by a corresponding user input. This means that a reduction made by the crane control or an increase in the rotational speed of the drive unit or the swivel angle of at least one variable displacement pump can be overridden at any time by user input. A conceivable user input represents the operation of the accelerator pedal.

The speed of the drive unit is increased according to the invention until the determined from the current speed of the drive unit or from the speed of the at least one variable volume flow corresponds to the requested volume flow or converges against it. The volume flow determined from the speed is calculated as a function of individual specific pump parameters. In this way, depending on the known speed at which the drive unit drives the at least one variable displacement pump, a theoretically possible volume flow at the outlet of the variable displacement pump can be concluded. However, this assumption is only valid as long as the at least one variable displacement pump or the powered consumer works without load.

The drive unit may preferably be an internal combustion engine, in particular a diesel engine, or else an electric or hybrid engine. The process execution is independent of the desired system structure of the hydraulics. The one or more consumers and the at least one pump can be connected as an open or closed hydraulic circuit.

The desired movement speed of the crane actuator or hydraulic consumer is determined by user input. Based on the user input, the crane control determines the energy required for this purpose, ie the required volume flow, which must be provided by the at least one variable displacement pump to the hydraulic consumer or consumers. The crane control is responsible for setting the desired movement speed. For this purpose, controls or regulates the crane control, if necessary, the drive unit of the crane and at least one adjustable hydraulic pump.

In addition, optionally another crane-specific parameters for the control or regulation of the drive unit can be taken into account. Possible parameters represent, for example, one or more values representing the height level above normal zero of the crane and / or a charging process of an energy store and / or the efficiencies of all or at least a portion of the consumers and / or at least one environmental condition, in particular the ambient temperature of the crane, and / or characterize a direct specification, in particular target speed specification of the crane operator. Environmental conditions, such as external pressure and ambient temperature, may affect the working conditions of the hydraulic system. Charging an energy storage may require a higher engine speed. At least one or at least some of these values can be taken into account by the crane control for the control and / or regulation of the rotational speed or the swivel angle of at least one variable displacement pump. The consideration takes place either additionally or alternatively requested volume flow for at least one consumer

Control of the speed is understood to mean both an increase and a reduction in the current speed. The same applies to the control or regulation of the swivel angle. Depending on the requested volume flow and / or a further parameter, this can optionally be reduced or increased.

It can be provided that at least one proportionally controllable directional seat valve is provided, which is connected between at least one variable displacement pump and at least one consumer. In this case, it may be appropriate be that in dependence on the requested volume flow and / or another parameter additionally control or regulation of at least one directional seat valve takes place. Depending on the user input, for example, a signal for controlling at least one valve is generated. Depending on the input signal, a volume flow is established which the valve can pass to the hydraulic consumer. The crane control can calculate this volume flow.

The directional seat valve is adjusted for example via a suitable adjusting mechanism, in particular an electromagnet.

It proves to be advantageous if priority is given to control of the swivel angle and only if necessary, a control of the speed of the drive unit is made. If the drive motor is idling, the displacement of the at least one hydraulic pump with the tilt angle is first changed as a function of the requested volume flow and / or another parameter. If the requested volume flow exceeds the volume flow which can be supplied via the current swivel angle, the engine speed is tracked. By increasing the engine speed, the volume delivered can be increased up to the requested volume flow.

It is expedient if the requested volume flow is adjusted via at least one operating lever of the crane. One or more control levers are provided for example in the crane cab. By operating the lever, ie deflection of the lever from the neutral position to the end position, the crane operator can set the desired volume flow. For example, at least one operating lever can be deflected from a middle position, ie neutral position, in four directions. In this case, the lever position in conjunction with one or more reductions represents the desired volume flow. Due to various operations, for example, an approach to a shutdown limit of the working area limitation, the crane control determines so-called reductions. These are usually in the range between 0 to 100%, with an amount of 100% corresponds to no reduction. The specification by the operating lever is charged with such a reduction and determines a final reduced flow rate.

The signals of at least one control lever can be transmitted either via a BUS connection or alternatively via a radio link to the crane control.

To control the speed of the drive unit, the crane control must determine a corresponding desired speed as a function of the requested volume flow. The determination can be made using a map. The map contains torque and / or speed curves with respective fuel consumption of the drive unit. Such a map is ideally stored in the crane control. For example, the relationship between hydraulic pressure and engine speed and / or for at least one characteristic field of the relationship between torque and speed is shown for at least one characteristic field. For each value of one of the characteristic fields, the associated fuel consumption, in particular in kilograms per hour, shown.

If a load acts on the consumer or the at least one variable displacement pump, the actual volume flow deviates from the volume flow calculated from the rotational speed. In particular, the actual volume flow falls below the calculated volume flow. In this case, it is expedient if the volume flow determined from the instantaneous engine power is adjusted to the requested volume flow by controlling the rotational speed. The volume flow determined from the instantaneous engine power can optionally or alternatively be determined from the applied pump pressure at the outlet of the at least one variable displacement pump. For this purpose, for example, a corresponding sensor for detecting the output pressure can be used.

In a particularly advantageous embodiment, it is conceivable that in advance the speed is increased until the volume flow determined from the instantaneous speed corresponds to the requested volume flow or converges against it. Subsequently, a volume flow is determined from the instantaneous engine power or the instantaneous pump output pressure. This calculated volume flow is fed as input value to a controlled system, which adjusts the calculated volume flow to the requested volume flow by controlling the speed of the drive unit. In particular, it is expedient to use a controller, for example an I controller, wherein the requested volumetric flow rate is used as the nominal value and the volumetric flow rate determined from the instantaneous engine power and the instantaneous pump pressure is used as actual value.

Against this background, it is advantageous if the crane control system adapts the acceleration and / or deceleration ramps of the rotational speed of the drive assembly individually and load-dependent. For example, the readjustment time of the controller used can be used to control the speed with which the output signal of the controller used follows the input signal. This time is dynamically adjustable.

In addition, it may be provided that changes in the requested volume flow are delayed and / or accelerated by means of ramp-function generator. As a result, the engine speed and thus the crane itself are calmed to achieve a uniform as possible driving behavior. The rise and / or fall time or start and end value are dynamically adjustable.

In the event that the hydraulic drive of the crane has a plurality of hydraulic consumers, it may be advantageous if the crane control summarizes the individual requested volume flows of the respective consumers to a total demand. The method described above is then applied to the specific total demand, the total demand in this case corresponding to the requested volume flow. If the determined total requirement exceeds the maximum possible delivery volume of the at least one variable displacement pump, then the crane control system must adjust the maximum possible delivery volume to the individual delivery split hydraulic consumers. In particular, the distribution is proportional to the respective volume flow demand of the individual consumers.

In a further advantageous embodiment of the invention can be provided that the mechanical drive train is disengaged if the crane control detects idling. In particular, the crane control can wait for a certain time interval after determining an idle operation until it disengages the drive train of the superstructure as close as possible to the drive unit. The defined time interval may, for example, be in the range of one minute. This reduces the losses in mechanical drive shafts and transmissions. This solution proves to be particularly advantageous in a single-engine crane in which the superstructure is driven by the undercarriage engine. In this case, the manual transmission is mounted very close to the engine, which serves for driving as well as for crane operation. Thus, the entire drive train to the superstructure with all losses (angle gear) can be decoupled and yet the complete power is available after about one to two seconds again for crane operation. Alternatively or in addition to disengaging, automatic shutdown of the power pack by the controller may be considered.

The invention further relates to a hydraulic crane drive with a crane control for carrying out the method according to the invention or for carrying out an advantageous embodiment of the method according to the invention. It is obvious that the crane drive or the crane control has corresponding means for carrying out the method. This includes a corresponding computer and control logic, which can be implemented in particular hardware or software. Consequently, the crane drive according to the invention has the same advantages and properties as the method according to the invention or an advantageous embodiment of the method according to the invention, which is why it is not intended here again to address a repetitive description of these features.

Furthermore, the invention relates to a crane having the crane drive according to the invention. The advantages and properties of the crane obviously correspond to those of the crane drive according to the invention.

Figur 1:

ein Schaltbild des erfindungsgemäßen Kranantriebs,

Figur 1a:

eine Übersicht über die verwendeten Eingangsparameter der Kransteuerung,

Figur 2:

ein Funktionsschaubild des erfindungsgemäßen Regelalgorithmus zur Ausführung des erfindungsgemäßen Verfahrens,

Figur 3:

eine Diagrammdarstellung zur Verdeutlichung der Sprungantwort des verwendeten I-Reglers,

Figur 4:

eine Diagrammdarstellung einzelner Steuer- bzw. Regelgrößen gegenüber der Zeit,

Figur 5:

eine Diagrammdarstellung der Sprungantwort des verwendeten Hochlaufgebers,

Figur 6:

ein Funktionsschaubild eines alternativen Regelalgorithmus zur Ausführung des erfindungsgemäßen Verfahrens,

Figur 7:

eine Diagrammdarstellung der Sprungantwort des im Funktionsschaubild der Figur 7 verwendeten Hochlaufgebers,

Figur 8:

eine Diagrammdarstellung der Übertragungsfunktion des im Funktionsschaubild der Figur 7 verwendeten PT1-Gliedes und

Figur 9:

ein Messdiagramm für ein Anwendungsszenario des Regelalgorithmus der Figur 7.

Further advantages and details of the invention will be explained in more detail below with reference to an embodiment shown in FIGS. Show it:

FIG. 1:

a diagram of the crane drive according to the invention,

FIG. 1a

an overview of the input parameters of the crane control,

FIG. 2:

a functional diagram of the control algorithm according to the invention for carrying out the method according to the invention,

FIG. 3:

a diagram representation to illustrate the step response of the I-controller used,

FIG. 4:

a diagram of individual control variables with respect to time,

FIG. 5:

a diagram of the step response of the ramp function generator used,

FIG. 6:

a functional diagram of an alternative control algorithm for carrying out the method according to the invention,

FIG. 7:

a diagram representation of the step response of the functional diagram of FIG. 7 used ramp-function generator,

FIG. 8:

a diagram of the transfer function of the function diagram of FIG. 7 used PT1 member and

FIG. 9:

a measurement diagram for an application scenario of the control algorithm of FIG. 7 ,

FIG. 1 shows a schematic diagram of the crane drive according to the invention. The crane drive comprises a drive motor 1, which is designed, for example, as an internal combustion engine, in particular diesel engine, and represents the central mobile crane drive. The connection to the variable displacement pump 3 is realized via the transmission 2 with a constant transmission ratio. The speed of the drive motor 1 can be controlled by a motor controller, not shown, in the range between a minimum and maximum engine speed. The central crane controller 10 is communicatively connected to the engine controller.

Depending on the engine speed of the drive motor 1 and depending on the pump displacement V _{G, PU, the} adjustable hydraulic pump 3 delivers a volume flow Q _PU to the connected hydraulic consumer 7 and to other hydraulic consumers 11 emphasis is placed on economical fuel consumption. In the following, the method according to the invention with a focus on the consumer 7 will be described. In principle, the other consumers 11 can or should also be taken into account in the process execution.

The displacement V _{G, PU of} the hydraulic pump 3 can be controlled via the pivot angle of the hydraulic pump 3, wherein a change in the pivot angle is achieved by means of an adjusting mechanism. The adjusting mechanism is a proportionally controllable electromagnet whose control current I _{pump is} generated by the crane control 10.

The volume flow Q _PU at the output of the variable displacement pump 3 is primarily regulated by the pivot angle. Is the maximum displacement V _{G, MAX} at maximum Tilting angle exhausted, can be further increased by increasing the engine speed of the flow Q _PU .

At the output line of the variable displacement pump 3, a pressure sensor 4 is also arranged, which detects the output side pressure p _PU and the controller 10 communicates.

The variable displacement pump 3 feeds a hydraulic consumer, which is designed in the figure representation as a hydraulic motor 7 for driving a hoist winch. Hydraulic motor 7 and variable 3 are connected via a 4/3-way seat valve 5 to reverse the flow direction and control of the flow rate. The valve is actuated by a proportionally controllable electromagnet. The necessary control current I _valve is provided by the crane control. This determines the appropriate control current I _{valve as a} function of the requested volume flow, which sets the possible flow rate at the valve to the requested volume flow.

The speed of movement of the hydraulic motor 7 changes as a function of the volume flow Q _PU , which is transmitted by the variable displacement pump via the valve 5 to this. A load attached to the crane winch can generate a load moment on the winch or the hydraulic motor, which counteracts the drive torque of the drive motor 1 when the valve 5 is activated and simultaneously increases the pressure p _PU to the pump 3.

The crane operator has the option of influencing the volume flow Q _PU via the operating lever 6. The degrees of freedom of the operating lever 6 are determined by an axbox. In the zero or mid position, no actuation of the hydraulic motor 7. The deflection of the control lever in the x- or y-axis direction is detected by the crane control 10 and converted in conjunction with the valve current I _valve in the requested volume flow Q _driver .

The control lever is self-restoring, so that it is always brought into the neutral position, ie in the center position without any force.

Via an accelerator pedal 9, the engine speed of the drive motor 1 can be changed manually in the range of maximum and minimum speed.

For the control or regulation of the engine speed or the swivel angle of the pump 3, additional parameters can additionally be taken into account for the required volume flow. FIG. 1a gives a brief overview of possible parameters to be included. For example, in addition, the ambient temperature of the crane or its height level can be included in order to take into account possible environmental values that have an influence on the operation of the hydraulics.

Furthermore, a specification of the operator, for example, the selection of a desired setpoint speed of the drive unit can be taken into account. In the same way, a charging process of an energy storage device can influence the specific rotational speed or the swivel angle, since the charging process regularly has an increased energy requirement.

Examples of further parameters include the efficiencies of the consumers 7, 11 and any other crane-specific sensor values or ambient conditions.

The aim of the crane control 10 is to determine an optimum engine speed or an optimal operating speed taking into account the parameters mentioned. This can result in a noticeable reduction in noise emission of the crane in addition to a reduced fuel consumption.

FIG. 2 shows a functional diagram of the control algorithm according to the invention for speed tracking. Blocks 1 to 8 correspond to the individual components according to FIG. 1 , wherein the same components are provided with identical reference numerals. The engine 1 provides information about its actual power P _MOT or actual speed n _MOT to the crane control 10. In addition, the output pressure p _{PU is} transmitted to the crane control of the variable displacement pump 3 via the sensor 4.

Furthermore, the crane control has knowledge of the set control current I _valve on Wegesitzventil 5. In addition, the deflection of the operating lever 6 is made available by bus or wireless transmission of the crane control 10.

n _MOT steht für die Motordrehzahl, V_G,PU für das Schluckvolumen der Pumpe 3 und u_PU,MOT für das Übersetzungsverhältnis des Getriebes 2. Nimmt man das Schluckvolumen V_G,PU und die Übersetzung u_PU,MOT als konstant an, kann man aus Gleichung 1 schlussfolgern, dass sich der Volumenstrom Q_PU1 proportional zur Drehzahl n _MOT ändert. Es gilt: $$Q_{\mathit{PU}1}=f\left(n_{\mathit{MOT}}\right)$$

From the data provided, the crane control continuously calculates several volume flows. The requested volume flow Q _driver is calculated based on the control of the operating lever 6 and the required valve current I _valve . The calculation of the volume flow Q _PU1 is carried out according to Equation 1 as a function of the current engine speed n _MOT and the maximum absorption volume of the pump 3. It should be noted that the maximum displacement volume of the hydraulic pump is always calculated, although the actual displacement is not activated Valve set to zero. $$Q_{\mathit{PU}1}\left[\frac{l}{\min }\right]=\frac{n_{\mathit{MOT}}\left[\frac{U}{\min }\right]•V_{G.\mathit{PU}}\left[\frac{l}{U}\right]•u_{\mathit{PU}.\mathit{<figure-callout\; id="1000"\; label="MOT"\; filenames="imgf0004.png,imgf0008.png"\; state="\{\{state\}\}">MOT</figure-callout>}}}{1000•1000}\Rightarrow Q~n_{\mathit{MOT}}.\mathit{at}:V_{G.\mathit{PU}}=V_{G.\mathit{MAX}}=\mathit{const},$$

n _MOT stands for the engine speed, V _{G, PU} for the displacement of the pump 3 and u _{PU, MOT} for the transmission ratio of the transmission 2. Assuming the displacement V _{G, PU} and the translation u _{PU, MOT} as constant, you can from equation 1 conclude that the volume flow Q _{PU1 changes in} proportion to the speed n _MOT . The following applies: $$Q_{\mathit{PU}1}=f\left(n_{\mathit{MOT}}\right)$$

Due to the instantaneous engine power P _MOT and the existing pump pressure p _PU , a further volume flow Q _{PU2 is} calculated. $$Q_{\mathit{PU}2}\left[\frac{l}{\min }\right]=\frac{P_{\mathit{MOT}}\left[\mathit{kW}\right]•600}{p_{\mathit{PU}}\left[\mathit{bar}\right]}\Rightarrow Q~P_{\mathit{MOT}}.\mathit{in\; which}:P_{\mathit{MOT}}=f\left(n_{\mathit{MOT}}\right)$$

From equation 3 it can be concluded that the volume flow Q _{PU2 changes in} proportion to the power. Assuming that the power P _{MOT increases} with increasing speed n _MOT , the power P _{MOT is} again proportional to the speed n _MOT . The speed n _MOT is maximally increased up to the upper speed limit of the drive motor 1. The following applies: $${\mathrm{<figure-callout\; id="2"\; label="Q\; PU"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">Q\; </figure-callout>}}_{\mathit{PU}}=f\left(P_{\mathit{MOT}}\right).\mathrm{With}{P}_{\mathit{MOT}}=f\left(n_{\mathit{MOT}}\right)<figure-callout\; id="2"\; label="\Rightarrow \; Q\; PU"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">\Rightarrow \; </figure-callout>Q_{\mathit{PU}}{\mathit{}2}_{}=f\left(n_{\mathit{MOT}}\right)$$

$$Q_{\mathit{PU}2}\ge Q_{\mathit{Fahrer}}$$

From the equations 2 and 4 it can be seen that the volume flow Q _{PU is} always dependent on the rotational speed n _{MOT of} the drive motor 1. The engine speed n _MOT must now be changed until Equation 5 and 6 are met. $$Q_{\mathit{PU}1}\ge Q_{\mathit{<figure-callout\; id="2"\; label="driver\; Q\; PU"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">driver\; </figure-callout>}}$$

$$Q_{\mathit{PU}}$$$${\mathit{}2}_{}\ge Q_{\mathit{driver}}$$

The general formula for engine speed based on a delivered volume flow is: $$n_{\mathit{MOT}}\left[\frac{U}{\min }\right]=\frac{Q_{\mathit{PU}}\left[\frac{l}{\min }\right]•1000•1000}{u_{\mathit{PU}.\mathit{MOT}}•V_{G.\mathit{PU}}\left[\frac{l}{U}\right]}$$

If the drive motor 1 is idling, the displacement of the hydraulic pump 3 is changed with the tilt angle of the hydraulic pump 3. If the driver requests a higher amount of consumption than the pump 3 can deliver V _{G, MAX} and idling gas at maximum displacement, the engine speed n _MOT must now be increased to promote the required quantity. From equations 2 and 4 it is apparent that increasing the volume flows Q _PU1 and _PU2 Q proportional to the engine speed N _mot. The crane control system 10 continuously determines a volume flow Q driver desired by the _driver and controls the engine speed n _MOT such that both volume flows Q _PU1 and Q _{PU2 correspond} at least to the desired volume flow Q _driver .

In the case of control, a distinction can be made between two cases. Case 1 applies to an unloaded hydraulic motor 7.

Case 1:

The crane controller 10 determines the driver's desired flow rate Q _driver. The engine speed n _MOT is changed until Q _PU1 corresponds to the volume flow of the driver Q _driver . Subsequently, the crane control 10 calculates the volume flow Q _PU2 on the basis of the instantaneous engine power P _MOT and the pump pressure p _PU . For the unloaded hydraulic motor 7 Q _{PU2 is} greater than Q _PU1 . This means that there is enough engine power P _MOT to satisfy the condition of Equation 6, and that a further increase in the engine speed n _{MOT is} not required.

Case 2:

In the case of a loaded hydraulic motor 7, the following applies:
The crane controller 10 determines the driver's desired flow rate Q _driver. The engine speed n _MOT is changed until Q _PU1 corresponds to the volume flow of the driver Q _driver . Subsequently, the crane control 10 calculates the volume flow Q _PU2 on the basis of the instantaneous engine power P _MOT and the pump pressure p _PU . Since the loaded hydraulic motor 7 is a counter-torque to the drive torque of the drive motor 1, results in this case, a volume flow Q _PU2 , which is lower than Q _PU1 . The provided motor power P _MOT is not sufficient to satisfy the condition of equation 6. As engine power P _{MOT also} increases with increasing engine speed n _MOT , a further increase in engine speed n _{MOT is} required.

1. 1. Die Kransteuerung 10 ermittelt kontinuierlich den gewünschten Volumenstrom Q_Fahrer . Anhand des geförderten Volumenstroms Q_PU wird mit Gleichung 7 die Sollmotordrehzahl n _Soll gerechnet und an das Motorsteuergerät weitergereicht. Ist diese Motordrehzahl n _Soll kleiner als die Minimaldrehzahl des Antriebsmotors 1, läuft der Antriebsmotor 1 mit Minimaldrehzahl. Ist diese Motordrehzahl n _Soll größer als die Maximaldrehzahl des Antriebsmotors 1, läuft der Antriebsmotor 1 mit Maximaldrehzahl.
2. 2. Während der Verbrennungsmotor 1 beschleunigt, ermittelt die Steuerung 10 den aktuellen Volumenstrom Q_PU1.
3. 3. Erreicht der Volumenstrom Q_PU1 annähernd den gleichen Wert wie Q_Fahrer , wird ein I-Regler 20 (Figur 2) aktiviert, der den Volumenstrom Q_Fahrer als Sollwert und den Volumenstrom Q_PU2 als Istwert erhält.
4. 4. Liegt der Volumenstrom Q_PU2 unter Q_PU1, so wird die Motordrehzahl n _Soll solange erhöht, bis der Volumenstrom Q_PU2 dem Volumenstrom des Fahrers Q_Fahrer entspricht oder die maximale Motordrehzahl erreicht ist. Es kann davon ausgegangen werden, dass mit steigender Motordrehzahl n _MOT auch die Motorleistung P_MOT steigt.

The method according to the invention therefore provides the following steps:

1. 1. The crane control 10 continuously determines the desired volume flow Q _driver . Based on the funded volume flow Q _PU is calculated with equation 7, the _target engine speed n _target and passed to the engine control unit. If this engine speed n _{Soll is} less than the minimum speed of the drive motor 1, the drive motor 1 runs at minimum speed. If this engine speed n _{setpoint is} greater than the maximum speed of the drive motor 1, the drive motor 1 runs at maximum speed.
2. 2. While the internal combustion engine 1 is accelerating, the controller 10 determines the current volume flow Q _PU1 .
3. 3. If the volume flow Q _PU1 reaches approximately the same value as Q _driver , an I controller 20 (FIG. FIG. 2 ), which receives the volume flow Q _driver as the setpoint and the volume flow Q _PU2 as the actual value.
4. 4. If the volume flow Q _{PU2 is} below Q _PU1 , then the engine speed n _{setpoint is} increased until the volume flow Q _{PU2 corresponds to} the volume flow of the driver Q _driver or the maximum engine speed has been reached. It can be assumed that with increasing engine speed n _MOT also the engine power P _MOT increases.

The concrete control of the I-controller 20 is in FIG. 2 seen. The I-controller 20 is used to compensate for the difference of Q _driver to Q _PU2 (x). For this _purpose, the control difference e is determined from the setpoint Q _driver and the actual value Q _PU2 and supplied to the controller 20. The I controller 20 generates the control signal Q _{I controller} (y) at the output.

To clarify the step response of the I-controller is on FIG. 3 referring to the course of the signal Q _driver and the control output signal Q _{I controller} over time. The time delay is due to the circulation time of the controller. About the reset time, the speed at which the output of the I-controller 20 follows the input signal Q _driver is controlled. This time is dynamically adjustable.

The output signal Q _{I controller} (y) of the I controller 20 and the volume flow Q _driver are added and passed to the ramp generator 30 as an input signal. This achieves a delay of the requested volume pressure. FIG. 5 shows the step response of the ramp-function generator 30. The purpose of implementing the ramp-function generator 30 is to calm the engine speed n _MOT as well as the mobile crane itself, and thus to ensure as uniform a ride as possible. The rise and fall times with which the output of the ramp-function generator 30 follows the input signal can be controlled dynamically.

FIG. 4 shows the course of the individual control and regulating signals of the _desired and actual engine speed n _target , n _actual , and the individual signals of the volume flows Q _driver , Q _PU1 , Q _PU2 , Q _{I controller} over time. Until the time t ₁ no input is made by the crane operator, so that the value for Q _driver = 0 is assumed. In this case, the target engine speed n _setpoint corresponds to the value 0 and the motor _actual speed n _actual corresponds to the speed of the drive motor 1 in the idle state.

The signal Q _PU1 shows the currently possible flow rate with idle gas and maximum displacement V _{G, MAX} , whereas the signal Q _{PU2 characterizes} the possible flow rate due to the instantaneous engine power P _MOT in the idle gas and the measured pressure p _PU . Since the control is not yet active at this time, the output value of the I-controller 20 Q _{I controller has} the value 0.

At the time t ₁ , the crane operator actuates the lever 6 for controlling the crane drive, so that the value for the signal Q _driver assumes a value> 0. The value for the target engine speed n _Soll follows the specification of the control loop and the _actual engine speed n _Ist follows the respective engine speed. Since Q _PU1 depends on the actual engine speed n _actual , this value also follows the actual engine speed n _actual as long as the variable displacement pump 3 is set to the maximum displacement V _{G, MAX} . By the applied volume flow to the consumer (s) 7, these are controlled accordingly. The acting pressure p _PU on the variable displacement pump 3 leads to a drop in the actual flow rate of the variable displacement pump 3, so that the value for Q _{PU2 sags} and _{falls below} the value Q _PU1 .

In this case, the engine speed n _{setpoint is} increased until the value for Q _PU1 approaches or corresponds to the value Q _driver (time t ₂ ). Since the actual volume flow Q _{PU2 is} below the requested volume flow Q _driver , the I regulator 20 is added (time t ₂ ) and the target engine speed n _{setpoint is} increased until the value for Q _PU1 ≥ Q is the _driver .

At time t ₃ , the operating lever 6 is relieved and brought back to the zero position. The value for Q _Driver decelerates so that all values return to their original values.

FIG. 6 shows a functional diagram of the control algorithm for speed tracking according to an alternative embodiment of the invention. Blocks 1 to 8 correspond to the individual components according to FIG. 1 , wherein the same components are provided with identical reference numerals. The engine 1 supplies information about its engine torque M _MOT or its actual rotational speed n _MOT to the crane control system 10. In addition, the output pressure p _PU and the volume flow Q _{PU are} transmitted to the crane control 10 by the variable displacement pump 3 via the sensor 4.

Furthermore, the crane control has knowledge of the set control current I _valve on Wegesitzventil 5. In addition, the deflection of the operating lever (MS) 6 is made available by bus system or radio transmission of the crane control 10.

The crane control receives as target specification a desired volume flow of the driver (Q _driver ). The driver determines the volume flow Q _driver by the control of the operating lever 6 and the associated setting of the valve currents (I _valve ). The aim of the control is to calculate a suitable engine speed η _{MOT_Max} for the desired volume flow Q _driver , at which the volume flow of the crane pump Q _PU corresponds to the desired set volume flow Q _driver . The calculation and adjustment of the engine speed takes into account the working speed and the work performance.

If the drive motor 1 is idling, the displacement of the hydraulic pump (s) 3 is changed with the swivel angle of the hydraulic pump (s) 3. If a higher consumption amount requested, as the pump can promote 3 at maximum displacement idle by the driver now has the engine speed η _MOT be increased in order to promote the required amount.

The flow Q _driver is according to equation 8 of the engine speed, the maximum displacement V _{G, PU, Max of} the pump 3 and the gear ratio pump motor dependent. It should be noted that 3 V _{G, PU, Max} = constant are always calculated with the maximum displacement of the hydraulic pump (s).

Working speed:

$$Q_{\mathit{driver}}\left[\frac{l}{\min }\right]=\frac{n_{\mathit{MOT}.\mathit{SPEED}}\left[\frac{U}{\min }\right]•V_{G.\mathit{PU}.\mathit{MAX}}\left[\frac{l}{U}\right]•u_{\mathit{PU}.\mathit{<figure-callout\; id="1000"\; label="MOT"\; filenames="imgf0004.png,imgf0008.png"\; state="\{\{state\}\}">MOT</figure-callout>}}}{1000•1000}\Rightarrow Q_{\mathit{driver}}~n_{\mathit{MOT}.\mathit{SPEED}}$$

Assuming in addition to the displacement and the translation as constant, it can be concluded from equation 8, that the desired volume flow changes in proportion to the speed. If one converts this equation after the engine speed, one obtains the following equation: $$n_{\mathit{MOT}.\mathit{SPEED}}\left[\frac{U}{\min }\right]=\frac{Q_{\mathit{driver}}\left[\frac{l}{\min }\right]•1000•1000}{u_{G.\mathit{PU}.\mathit{MAX}}\left[\frac{l}{U}\right]•u_{\mathit{PU}.\mathit{MOT}}}\Rightarrow n_{\mathit{MOT}.\mathit{SPEED}}~Q_{\mathit{driver}}$$

With the help of equation 9, the desired volume flow Q _{driver is converted} into an engine speed η _{MOT, SPEED} .

Working hours:

In order to take into account the work that the crane operator desires with the volume flow Q _driver , the current engine power P _Mot must be calculated. $$P_{\mathit{MOT}}\left[\mathit{kW}\right]=\frac{Q_{\mathit{driver}}\left[\frac{l}{\min }\right]•{\mathrm{<figure-callout\; id="600"\; label="p\; PU\; bar"\; filenames="imgf0004.png,imgf0008.png"\; state="\{\{state\}\}">p\; </figure-callout>}}_{\mathit{PU}}\left[\mathit{bar}\right]\left[\mathit{}\right]}{600}$$

The component p _PU represents the pump pressure of the pump 3. An engine power P _Mot can also be calculated by the following formula: $$P_{\mathit{MOT}}\left[\mathit{kW}\right]=\frac{M_{\mathit{Mot}}\left[\mathit{nm}\right]•{\eta }_{\mathit{Mot}.\mathit{power}}\left[\frac{l}{\min }\right]}{9549}$$

und stellt nach der Drehzahl η_{Mot, POWER} um, so erhält man folgende Gleichung: $${\eta }_{\mathit{Mot},\mathit{Power}}\left[\frac{l}{\min }\right]=\frac{Q_{\mathit{Fahrer}}\left[\frac{l}{\min }\right]•p_{\mathit{PU}}\left[\mathit{bar}\right]•9549}{600•M_{\mathit{Mot}}\left[\mathit{Nm}\right]}\Rightarrow {\eta }_{\mathit{MOT},\mathit{POWER}}\sim Q_{\mathit{Fahrer}}$$

Where M _{Mot stands} for the engine torque. Substituting equations 10 and 11 $$\frac{Q_{\mathit{driver}}\left[\frac{l}{\min }\right]•{\mathrm{<figure-callout\; id="600"\; label="p\; PU\; bar"\; filenames="imgf0004.png,imgf0008.png"\; state="\{\{state\}\}">p\; </figure-callout>}}_{\mathit{PU}}\left[\mathit{bar}\right]\left[\mathit{}\right]}{600}=\frac{M_{\mathit{Mot}}\left[\mathit{nm}\right]•{\eta }_{\mathit{Mot}.\mathit{power}}\left[\frac{l}{\min }\right]}{9549}$$

and turns after the speed η _{Mot, POWER} , we obtain the following equation: $${\eta }_{\mathit{Mot}.\mathit{power}}\left[\frac{l}{\min }\right]=\frac{Q_{\mathit{driver}}\left[\frac{l}{\min }\right]•p_{\mathit{PU}}\left[\mathit{bar}\right]•9549}{600•M_{\mathit{Mot}}\left[\mathit{nm}\right]}\Rightarrow {\eta }_{\mathit{MOT}.\mathit{POWER}}~Q_{\mathit{driver}}$$

From both Equations 9 and 12 it can be seen that the volume flow Q _{driver is} always dependent on the rotational speed η _{MOT of} the drive motor 1. From the two calculated engine speeds (η _{MOT, SPEED} , η _{MOT, POWER} ), the larger one is sent to the engine control unit. The engine torque M _MOT required for the engine speed according to equation 12 can either be the engine torque currently output by the engine control unit or an engine torque determined from an engine characteristic field.

Even with this control algorithm, a distinction can be made between the two known cases. It can be seen from Equations 9 and 12 that the engine speeds η _{MOT, SPEED} , η _{MOT, POWER} increase in proportion to the volume flow. The crane control continuously determines these engine speeds from a volume flow Q _driver desired by the _driver . The larger of the two engine speeds is determined in block 40 and sent as desired speed η _{MOT, MAX} to the drive motor 1. After the setpoint speed η _{MOT, MAX} has been set, the crane pump delivers as much volume flow as corresponds to Q _driver .

Case 1 low loaded hydraulic motor 7:
Given are the following sizes: Q _driver = 200 l / min u _{PU, MOT} = 1000 η _{MOT, SPEED} = 847 rpm (according to equation 9) η _{MOT, POWER} = 477 rpm (according to equation 12) p _PU = 60 bar V _{G, PU, MAX} = 236 ccms P _MOT = 40 kW (according to equation 10) M _MOT = 400 Nm

The crane controller 10 determines from the driver's desired flow rate Q _driver's engine speeds η _{MOT, SPEED} and η _{MOT, POWER.} In the case of the unloaded hydraulic motor 7, the measured pump pressure p _{PU is} very low. The determined engine speed η _{MOT, POWER} will be much lower compared to the engine speed η _{MOT, SPEED} . This means that the engine speed η _{MOT, SPEED is sent} as set speed to the crane engine.

Case 2 heavily loaded hydraulic motor (7):
given:
Given are the following sizes: Q _driver = 200 l / min u _{PU, MOT} = 1000 η _{MOT, SPEED} = 847 rpm (according to equation 9) η _{MOT, POWER} = 1326 rpm (according to equation 12) p _PU = 250 bar V _{G, PU, MAX} = 236 ccms P _MOT = 80 kW (according to equation 10) M _MOT = 600 Nm

The crane controller 10 determines from the driver's desired flow rate Q _driver's engine speeds η _{MOT, SPEED} and η _{MOT, POWER.} In the case of the loaded hydraulic motor 7, the measured pump pressure p _{PU is} very high. The determined engine speed η _{MOT, POWER} will be much higher compared to the engine speed η _{MOT, SPEED} . This means that the engine speed η _{MOT, POWER is sent} as a set speed to the crane engine.

According to FIG. 6 the maximum motor speed η _{MOT, MAX} the downstream ramp generator (HG) 50 is supplied. The input signal on the ramp-function generator 50 is identified for clarity as η _{MOT, MAX, HG} , while the output signal is referred to as η _{MOT, MAX, PT1} . The ramp-function generator 50 of FIG. 6 It is used to calm the engine speed and therefore also the mobile crane, which allows the most even driving behavior possible.

FIG. 7 shows the step response of the ramp-function generator 50. The rise and fall times control the speed at which the output of the ramp-function generator follows the input signal. These times, as well as start and end values are dynamically adjustable.

The output signal of the ramp-function generator 50 is then fed to the PT1 element 60. A PT1 element is an LZI transmission element in control engineering which has a proportional transmission behavior with a delay of the first order.

The PT1 element receives as input the output signal η _{MOT, MAX, PT1 of} the ramp-function generator 50 and generates according to the in FIG. 8 illustrated transfer function, the output speed η _{MOT, MAX} , which is finally supplied to the engine control of the engine 1 as a target speed.

FIG. 9 Finally, FIG. 3 shows a measurement diagram which illustrates the time profile of the variables relevant for crane control in the described second case with heavily loaded hydraulic motor 7, that is, with comparatively high pump pressure p _PU . The requested volumetric flow Q _driver increases at the beginning and reaches a level of 200 l / min at time t = 20s. The actual engine speed is initially oriented in the time window t = 0 and t = 6s at the speed η _{MOT, SPEED} . From the time t = 6s the calculated engine speed η _{MOT, POWER} exceeds the engine speed η _{MOT, SPEED} , so that the actual engine speed η _{MOT, IST} the engine speed η _{MOT, POWER} follows. At the time t = 40s, the demand is reset to the volume flow and the speed is regulated down.

Claims (14)

1. Method for the speed synchronization of a hydraulic crane drive with at least one hydraulic consumer (7, 11), which is fed, via at least one hydraulic displacement pump (3), with an adjustable volumetric flow (Q_PU), wherein the at least one displacement pump (3) is driven by the drive unit (1) of the crane,
   characterized in that
   the speed (n_MOT) of the drive unit (1) and the pivot angle of the at least one displacement pump (3) are controlled and/or adjusted as a function of the requested volumetric flow (Q_FAHRER) for at least one consumer (7, 11), and on the basis of a further parameter, by the crane control (10),
   that the target speed (n_SOLL) is calculated from the requested volumetric flow (Q_FAHRER),
   that the speed synchronization can be overridden by a user input, in particular a gas pedal actuation (9), and
   the speed (n_MOT) of the drive unit (1) is increased until the volumetric flow (Q_PU1) determined from the instantaneous speed (n_MOT) corresponds to the required volumetric flow (Q_FAHRER) or converges towards the same.
2. Method according to claim 1, characterized in that, additionally, at least one proportionally controllable directional seated valve (5) is activated.
3. Method according to one of the preceding claims, characterized in that a control of the pivot angle occurs first, and a control of the speed (n_MOT) occurs as necessary.
4. Method according to one of the preceding claims, characterized in that the required volumetric flow (Q_FAHRER) is adjusted via at least one operating lever (6).
5. Method according to claim 6, characterized in that the current lever position is signaled to the crane control selectively via a bus connection and/or radio frequency connection.
6. Method according to one of the preceding claims, characterized in that the target speed (n_SOLL) of the drive unit (1) is determined based on at last one characteristic map, in particular of the drive unit (1).
7. Method according to one of the preceding claims, characterized in that the at least one further parameter is a value, which characterizes the height level above sea level of the crane, and/or a charging operation of an energy accumulator, and/or the efficiency/ies of all or at least a part of the consumers (7, 11), and/or at least one environmental condition, in particular the ambient temperature of the crane, and/or a direct specification, in particular target speed specification (n_SOLL) of the crane.
8. Method according to on of the preceding claims, characterized in that the volumetric flow (Q_RU1), determined from the instantaneous motor output (P_MOT), and/or of the instantaneous pump pressure (p_PU) can, via controlling of the speed (n_MOT), be adjusted to the required volumetric flow (Q_FAHRER).
9. Method according to one of the preceding claims, characterized in that the crane control (10) adapts, individually and load-dependently, to the acceleration- and/or deceleration ramps of the speed (n_MOT) of the drive unit (1).
10. Method according to one of the preceding claims, characterized in that the altering of the required volumetric flow (Q_FAHRER) is delayed and/or accelerated by means of a ramp function generator (30).
11. Method according to one of the preceding claims, characterized in that the crane control (10), in multiple hydraulic consumers (7, 11), combines the individual required volumetric flows into a total demand (Q_FAHRER), and divides the maximum delivery amount, proportionally to the respective requirement, among the consumers (7, 11), in the event that the total demand (Q_FAHRER) exceeds the maximum delivery amount.
12. Method according to one of the preceding claims, characterized in that the mechanical drive train is uncoupled in the event that the crane control (10) determines an idle operating mode.
13. Hydraulic crane drive, with a crane control (10), for performing the method according to one of the preceding claims.
14. Crane, in particular a mobile crane, with a crane drive according to claim 13.

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