EP3296466B1 - Method for controlling a drop-hammer - Google Patents

Description

The invention relates to a method and a device for controlling a free-fall hammer of a construction machine by means of a control / control device.

In generic construction machines with free-fall hammers, it is known to lift a large weight by hydraulic actuators in the air, which then passes back to the original position by the gravitational force. The weight hits a pile, which is driven by the kinetic energy into the ground. The ramming weights usually range from 3,000 kg to 15,000 kg.

From the US 4,802,538 A discloses a free-fall hammer with a movable within a cylindrical drum hammer piston, which can be lifted by means of a hydraulic circuit and hydraulic actuators. Also the WO 2008/049159 shows a free-fall hammer with a weight which can be raised by means of hydraulically operated lifting cylinder. The DE 24 22 931 A1 discloses a method and apparatus for continuous control the lifting height and the number of strokes of the percussion piston of a hydraulically driven free fall hammer.

In known from the prior art method for controlling free-fall hammer, it is known to control the free-fall hammer by entering three parameters in a control / control device of a hydraulic system. On the one hand, the residence time of the ramming weight between the individual strokes is set, on the other hand, the opening time of a corresponding hydraulic valve can be set and further the volume flow of a corresponding hydraulic pump can be determined. These settings must be adjusted by the driver during operation of the corresponding construction machine depending on the situation. Due to the lack or utilization of appropriate information of the hydraulic circuit, it is inevitable for the driver to constantly change these three variables.

By physical couplings of the hydraulic control results in influencing the settings or parameters with each other. If, for example, the volume flow of the hydraulic pump is increased, the pressure level in the hydraulic system increases, as a result of which more energy can be present in the hydraulic accumulator and the amplitude of the weight or of the freefall hammer can be increased or increased. To correct this, the driver must then reduce the opening time of the valve so that the same height can be achieved. If, for example, the volume flow of the hydraulic pump is set too low, the fall height of the free fall hammer can vary considerably. On the other hand, if the volumetric flow of the hydraulic pump is chosen to be too high, the hydraulic components can be subjected to a higher load and early failures of the hydraulic accumulator or other components of the hydraulic system can occur. Due to the high dynamics of the hydraulic free-fall hammer, the behavior of the hydraulic circuit due to temperature fluctuations also changes, which means that the driver must change or adapt these three variables throughout the operating time of the hammer.

The time delay of the entire system also makes it difficult and can only be done by trained personnel.

• einer einstellbaren Schlagenergie, welche sich durch eine einstellbare Wurfhöhe äußert;
• einer definierten Haltezeit, die das Fallgewicht auf dem Rammgut ruht, bevor der nächste Schlag eingeleitet wird; und
• einer maximalen Schlagfrequenzeinstellung, wobei beispielsweise eine möglichst schnelle oder eine definierte maximale Frequenz der Schlagwiederholungen möglich sein kann.

The object of the invention is therefore to provide a method for controlling a free fall hammer and a corresponding device, by means of which a simpler setting or control of the free fall hammer by the operator or driver is possible. It should be independent of external influences such as the outside temperature and / or the ground and regardless of other driver settings a defined behavior of the free fall hammer can be determined. This behavior consists of:

• an adjustable impact energy, which is expressed by an adjustable throw height;
• a defined holding time that rests the falling weight on the pile before the next blow is initiated; and
• a maximum rate setting, for example, as fast as possible or a defined maximum frequency of the repeats can be possible.

This object is achieved by a method having the features of claim 1. Advantageous embodiments are the subject of the dependent claims.

• Eingeben von Vorgabeparametern in die Regelungs-/Steuerungsvorrichtung durch eine Bedienperson;
• Erfassen aktueller Systemparameter der Baumaschine durch die Regelungs-/Steuerungsvorrichtung;
• Berechnen der Betätigungsdauer einer Hydraulikschaltung in Abhängigkeit von den Vorgabeparametern und von den Systemparametern; und
• Öffnen der Hydraulikschaltung für die berechnete Betätigungsdauer.

Thus, a method for controlling a free-fall hammer of a construction machine by means of a control / control device is provided, wherein the opening of a hydraulic circuit causes the free-fall hammer is lifted by means of an actuator. According to the invention, the method comprises the following steps:

• Inputting default parameters into the control device by an operator;
• Detecting current system parameters of the construction machine by the control device;
• Calculating the duration of operation of a hydraulic circuit in dependence on the default parameters and on the system parameters; and
• Opening the hydraulic circuit for the calculated duration of operation.

Advantageously, in contrast to the prior art, a simple and independent control of the hammer is possible. For this purpose, corresponding additional sensors can be used with which the state of the hydraulic circuit can be determined before the actual pitch. The sensors can be coupled to the control / control device and read from this. In this way, system parameters can be detected by the control device. It can be used in a hydraulic accumulator of the hydraulic circuit and the current flow rate of a hydraulic pump. With these characteristics, an operating period of the valve or the hydraulic circuit can now be calculated for a given throwing height, maximum or otherwise fixed beat frequency and / or dwell time. The calculation of the operating time can be done by the control / control device. This actuation period or opening time T _open is now switched to the valve or to the hydraulic circuit and thus triggered the litter, that is, the valve is actuated for the opening time T _open . The hydraulic circuit can be all hydraulic components necessary for the operation of the free-fall hammer or it can be the valve shown in the figures. If in this case of raising the freefall hammer by means of the actuator is mentioned, so it may also be a throwing or throwing or spinning the free fall hammer meant.

In a preferred embodiment, it may be provided that the default parameters include the impact energy, the residence time, the impact velocity, the impact height and / or the impact frequency.

The impact energy can in this case designate the energy with which the free-fall hammer hits a pile. The impact velocity and the impact height as well as the impact frequency are corresponding parameters of the free fall hammer. The impact speed may be the speed of the free fall hammer just before it hits the pile, the impact height may correspond to the distance traveled by the free fall hammer before striking the pile. The impact energy can be determined, for example, from the speed and weight of the free fall hammer by the control / control device. To detect the individual values, corresponding sensors can be provided on the free-fall hammer or on other components of the construction machine. The input default parameters may be setpoints, while the system parameters detected by the sensors may be at least partially corresponding actual values.

In a further preferred embodiment, it may be provided that the system parameters of the construction machine include the current hydraulic pressure in a high-pressure accumulator and / or the current delivery rate of a hydraulic pump and / or the speed of the falling ramming weight or weight. With the falling hammer this can be called the free fall hammer. By detecting these system parameters, it is easier to estimate, for example, the currently introduced by the free-fall hammer energy in the pile and calculate and so by means of the control / control device, if necessary, to vary the operating time so that desired by an operator of the construction machine Impact energies, residence times and / or beat frequencies can be achieved. If it is found, for example, that the free-fall hammer hits the pile with too low a speed and thus too little energy, then the Operation period be extended so that the free-fall hammer is lifted higher by means of the actuator or thrown and then hits with correspondingly higher speed and energy to the pile.

In a further preferred embodiment, it is thus conceivable that the system parameters are encompassed by the control / control device by means of corresponding sensors and / or that a control loop is provided which comprises deviations of the default parameters and / or the system parameters between individual strokes of the free-fall hammer and depends thereon the duration of operation of the hydraulic circuit varies. As a result, the system can react to deviations particularly easily and, if necessary, automatically adjust the actuation duration of the hydraulic circuit to changed parameters in such a way that, as a result, it is possible to work as closely as possible to the desired nominal powers or setpoints. The control loop can intervene between the individual ramming processes or openings of the hydraulic circuit and change the calculated specifications or operating periods in order to correct deviations of the desired values from the actual values which can be detected by means of the detected system parameters.

The invention further relates to an apparatus for operating a free-fall hammer with a hydraulic circuit and an actuator, the apparatus according to the invention a control / control device for carrying out the method according to one of claims 1 to 5 and at least one sensor for detecting the hydraulic pressure in a high-pressure accumulator and / / or at least one sensor for detecting the current delivery rate of a hydraulic pump and / or at least one sensor for detecting the speed of the falling hammer. The device can therefore be retrofitted to a construction machine and be executable suitable to the hydraulic equipment of the construction machine.

In a preferred embodiment, it is conceivable that the device has at least one high-pressure accumulator and / or at least one hydraulic pump and / or comprises at least one hydraulic circuit. Accordingly, the device can also be retrofitted to construction machines, which have not sufficiently procured hydraulic structures for the inventive operation of a free-fall hammer.

The invention is further directed to a construction machine with an apparatus according to claim 6 or 7, which is adapted to carry out a method according to one of claims 1 to 5, wherein the control / control device used according to the method is a control device of the construction machine or a is independent of the construction machine and can be coupled with this control / control device. Accordingly, an already existing on a construction machine control / control device for driving according to the invention of a free fall hammer can be used. Alternatively, a control / control device can be coupled to the construction machine so as to be able to carry out the method according to the invention independently of the construction machine.

In a further preferred embodiment, it is also conceivable that the high-pressure accumulator used in accordance with the method and / or the hydraulic pump used according to the method are associated components of the construction machine. Accordingly, said components of the construction machine can be used to control the free-fall hammer according to the invention.

Further details and advantages are given in the individual FIG. 1 called embodiment shown.

The FIG. 1 shows a schematic representation of a hydraulic circuit for driving a free-fall hammer 1 according to the invention.

In the resting state of the free fall hammer 1, all two cylinder chambers A and B of an actuator 2 via a valve 3 are connected to each other and there is everywhere the same system pressure. By pressing the valve 3, the upper Cylinder chamber A relieved against a tank 4 and thereby the ram weight 5 is accelerated upward against gravity. The energy for this is supplied by the hydraulic pump 6 and / or the high-pressure accumulator 7. After a certain time, the valve 3 is closed again. Due to the kinetic energy of the ram weight 5, this can move further upwards (the valve 3 does not hinder this movement). After reaching the highest point of the ramming weight 5, the weight 5 accelerates itself downwards by gravity and strikes the ramming material 8. In the Rammgut 8 may be a pillar.

An object of the invention is that the opening time of the valve 3 is calculated by means of the control / control device 10 so that a desired or set throw height can be achieved. In addition, the pressure level of the hydraulic pump 6 should be adjusted so that requirements of the driver such. B. the repetition frequency of the strokes can be met. As FIG. 1 can be removed, the control / control device 10 may be connected thereto for this purpose with the pump 6, the valve 3, the high-pressure accumulator 7, for example, provided at Rammgewicht 5 speed sensor and other system components. Via the connections corresponding sensor or control signals can be passed.

• Berechnung mithilfe vereinfachter mathematischen Formeln:
  Durch entsprechende vereinfachende Annahmen kann der Bewegungsablauf des Gewichtes 5 analytisch berechnet werden. Diese mathematischen Formeln können anschließend dazu verwendet werden, die Öffnungszeit zu berechnen.
• Lookup Tabelle:
  Es kann aus Versuchen oder aus theoretischen Betrachtungen vorab eine Tabelle erstellt werden. Durch entsprechendes Auslesen und interpolieren innerhalb der Tabelle kann die Zeit bestimmt werden d. h. es kann z. B. die Öffnungszeit T_open aus einem Kennfeld mit den Achsen Druck und Volumenstrom abgelesen werden.
• Berechnung mittels numerischen Modells:
  Aus einer numerischen Simulation / Optimierung kann die optimale Ansteuerzeit bzw. Betätigungsdauer berechnet werden. Es wird dabei ein numerisches Simulationsmodells des hydraulischen Hammers 1 mit den entsprechenden Ansteuerventilen simuliert. Aus mehreren Simulationsläufen kann die optimale Ansteuerzeit hergeleitet werden. Dieses Verfahren ist unter anderem unter dem Schlagwort Model Predictiv Control bekannt.
• Berechnung mithilfe komplizierten mathematischer Formeln:
  Analog zu den vereinfachten mathematischen Formeln können auch nichtlineare mathematische Gleichungen numerisch gelöst werden. Dies umfasst jedoch einen höheren Aufwand, da die Berechnung zur Laufzeit durch numerische Methoden durchgeführt werden muss.

For the calculation of the opening time, there are different variants; For all variants, the set parameters (impact energy, dwell time and / or maximum frequency) are taken into account by the driver:

• Calculation using simplified mathematical formulas:
  By appropriate simplifying assumptions, the movement sequence of the weight 5 can be calculated analytically. These mathematical formulas can then be used to calculate the opening time.
• Lookup table:
  It can be prepared from experiments or from theoretical considerations in advance a table. By appropriate reading and interpolating within the table, the time can be determined ie it can, for. B. the opening time T _open can be read from a map with the axes pressure and flow.
• Calculation by numerical model:
  From a numerical simulation / optimization, the optimum activation time or actuation duration can be calculated. In this case, a numerical simulation model of the hydraulic hammer 1 with the corresponding control valves is simulated. The optimum activation time can be derived from several simulation runs. This method is known, inter alia, under the keyword Model Predictive Control.
• Calculation using complicated mathematical formulas:
  Analogous to the simplified mathematical formulas, nonlinear mathematical equations can also be solved numerically. However, this involves a higher outlay, since the calculation must be carried out at runtime by numerical methods.

An example of "calculation using simplified mathematical formulas" is explained below:
As an example, the calculation of the opening time will be explained. This is the simplest variant, which is shown here.

1. 1.Beschleunigung des Rammgewichts
2. 2.Freier Fall (keine externe Krafteinwirkung außer der Gravitationskraft) des Rammgewichts 5.

The movement of the ramming weight can be divided into two areas or phases:

1. 1. acceleration of ramming weight
2. 2.Free case (no external force except gravitational force) of ramming weight 5.

nach oben beschleunigt wird. Daraus ergibt sich aus $$z\left(t\right)=\frac{1}{2}\frac{F{t}^2}{m}+{\dot{z}}_0\left(t=0\right)t+z_0\left(t=0\right)$$

der freien beschleunigten Bewegung einer Masse die Position zum Zeitpunkt T_open zu $$z\left(t_{\mathit{open}}\right)=\frac{\left(F_{\mathit{Aktor}}-\mathit{mg}\right)T_{\mathit{open}}{}^2}{2m}$$

During the first phase it can be assumed for simplicity that the ramming weight 5 with constant force F $$F=F_{\mathit{actuator}}-\mathit{mg}$$

is accelerated upwards. It follows $$z\left(t\right)=\frac{1}{2}\frac{F{t}^2}{m}+{\dot{z}}_0\left(t=0\right)t+z_0\left(t=0\right)$$

the free accelerated movement of a mass the position at time T _open to $$z\left(t_{\mathit{open}}\right)=\frac{\left(F_{\mathit{actuator}}-\mathit{mg}\right)T_{\mathit{open}}{}^2}{2m}$$

und die maximale Aufprallgeschwindigkeit zu $${\dot{z}}_{\mathit{max}}=\frac{T_{\mathit{open}}\sqrt{F_{\mathit{Aktor}}\left(F_{\mathit{Aktor}}-\mathit{mg}\right)}}{m}$$

Here it is assumed that the acceleration takes place from the rest position. Subsequently, the weight moves in the second phase in free fall (F _actuator = 0, that is, the actuator 2 exerts no force on the weight 5) continue - first upwards, then in free fall down again until it hits the pile 8. This results in the maximum drop height too $$z_{\mathit{Max}}=\frac{F_{\mathit{actuator}}\left(F_{\mathit{actuator}}-\mathit{mg}\right)T_{\mathit{open}}{}^2}{\mathrm{<figure-callout\; id="2"\; label="G\; m"\; filenames="imgf0001.png"\; state="\{\{state\}\}">G\; </figure-callout>}{m}^{}{}^2}$$

and the maximum impact speed too $${\dot{z}}_{\mathit{Max}}=\frac{T_{\mathit{open}}\sqrt{F_{\mathit{actuator}}\left(F_{\mathit{actuator}}-\mathit{mg}\right)}}{m}$$

berechnet und die Kraft kann durch den gemessenen aktuellen Hydraulikdruck $$F_{\mathit{Aktor}}=p{A}_{\mathit{Zylinder}}$$

abgeschätzt werden. Damit kann die Öffnungszeit T_open aus den Basisgleichungen berechnet werden. Diese einfache Berechnungsvorschrift vernachlässigt den aktuellen Volumenstrom der hydraulischen Versorgung und die Nichtlinearität des hydraulischen Hochdruckspeichers.For the calculation of T _open , the required switching time or operating time can now be determined from the driver's specifications. The maximum throw height becomes the impact energy in a free-fall hammer 1 from the relationship $$e=\mathit{mg}{z}_{\mathit{Max}}$$

calculated and the force can be measured by the current hydraulic pressure $$F_{\mathit{actuator}}=p{A}_{\mathit{cylinder}}$$

be estimated. Thus, the opening time T _open can be calculated from the basic equations. This simple calculation rule neglects the current volume flow of the hydraulic supply and the non-linearity of the high-pressure hydraulic accumulator.

An additional control loop R can be used to compensate for the uncertainties caused by temperature, tolerances and measurement errors.

It can be done as follows: Between the individual litters, the deviation between the target size z. B. impact energy and the measured impact energy calculated. This error can be used to improve the next litter. This type of regulation is also called iterative regulation. In this example the following procedure results: The measured impact velocity is measured. This allows the current impact energy to be calculated $$e_{\mathit{current}}=\raisebox{1ex}{$m{\dot{x}}^2$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$$

This value is compared with the default impact energy E. From this comparison, a correction of the calculated opening time z. B. with a P share k (control parameter) $$T_{\mathit{open}.p+1}=T_{\mathit{open}.p}+k\left(e-e_{\mathit{current}}\right)$$

As a result, disturbances can be corrected automatically by means of the control circuit R.

Claims (9)

1. Method for controlling a drop hammer (1) of a construction machine by means of a regulating/control device (10), wherein the opening of a hydraulic circuit (3) causes the drop hammer (1) to be lifted by means of an actuator (2),
   characterized in that
   the method includes the following steps:

   Inputting of default parameters into the regulating/control device (10) by an operator;

   detecting of current system parameters of the construction machine through the regulating/control device (10);

   calculating of the actuation period of a hydraulic circuit (3) depending upon the default parameters and upon the system parameters, and

   opening of the hydraulic circuit (3) for the calculated period of actuation.
2. Method according to claim 1, characterized in that the default parameters include the impact energy, the dwell time, the impact speed, the impact height, and/or the impact frequency.
3. Method according to claim 1 or 2, characterized in that the system parameters of the construction machine include the current hydraulic pressure in a high-pressure accumulator (7), and/or the current discharge flow of a hydraulic pump (6), and/or the speed of the dropping ramming weight (5).
4. Method according to claim 1, 2 or 3, characterized in that the system parameters are detected, by means of corresponding sensors, by the regulating/control device (10).
5. Method according to one of the preceding claims, characterized in that a regulating circuit is provided, which, between individual strokes of the drop hammer (1), detects deviations of the default parameters and/or of the system parameters and, dependently thereupon, varies the period of actuation of the hydraulic circuit (3).
6. Device for the operation of a drop hammer (1), including a hydraulic circuit (3) and an actuator (2),
   characterized in that
   the device includes a regulating/control device (10) for performing the method according to one of the claims 1 to 5, as well as at least one sensor for detecting the hydraulic pressure in a high-pressure accumulator (7), and/or at least one sensor for detecting the current discharge flow of a hydraulic pump (6), and/or at least one sensor for detecting the speed of the dropping ramming weight (5).
7. Device according to claim 6, characterized in that the device includes at least one high-pressure accumulator (7) and/or at least one hydraulic pump (6), and/or at least one hydraulic circuit.
8. Construction machine with a device according to claim 6 or 7, which is formed for carrying out a method according to one of the claims 1 to 5, characterized in that the regulating/control device (10), used according to the invention, is a regulating/control device (10) of the construction machine, or is a regulating/control device (10) independent of the construction machine, and couplable with the same.
9. Construction machine at least according to claim 8, for carrying out a method at least according to claim 3, characterized in that the high-pressure accumulator (7) used according to the invention, and/or the hydraulic pump (6), used according to the invention, are components assigned to the construction machine.

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