WO2008070884A1 - Method for identifying blockages in sprinkler devices and apparatus for carrying out this method - Google Patents

Abstract

In a method for identifying blockages in sprinkler devices (2) on heading and mining machines, the pressure and the flow rate of the medium to be fed to the sprinkler device are measured, the measured values are fed to an evaluation circuit and compared with the desired characteristic curve (12), which is measured for the sprinkler device, for the dependence of its flow rates on the operating pressure of a fault-free sprinkler device. Deviations from the desired characteristic curve of a fault-free sprinkler device are displayed and/or used as control signals for driving the heading and/or mining machine. The apparatus for carrying out the method is characterized in that a pressure sensor (4) and a flow rate sensor (7) for the medium which is to be fed to the sprinkler device are provided, the measured values from these sensors being passed to an evaluation circuit via signal lines; in that the evaluation circuit contains a memory for desired characteristic curves (12, 18) of the pressure-dependent profile of the flow rates of a fault-free sprinkler device and provides characteristic maps for the permissible deviation from the desired characteristic curve, and in that the evaluation circuit is connected to a display apparatus and/or a control element of the drive of the heading and mining machine.

Description

Method for detecting clogging of spraying devices and device for carrying out this method

The invention relates to a method for detecting clogging of spraying devices on propulsion or mining machines and to an apparatus for performing this method.

In propulsion and extraction machines, it is known to guide cooling liquid via nozzles to the working face or the chisel, wherein such spraying of cooling liquid is intended to prevent unacceptably high temperatures at the face and in this way make sparking and explosions impossible. Depending on the type of medium supplied, it is also possible to spray liquid via such nozzles in such a way that excessive dust formation is avoided. Due to contamination of the cooling liquid but it can come in such nozzles to a nozzle blockage, with such nozzle clogging in turn can result in that insufficient cooling liquid is supplied and sparking and explosions can not be reliably avoided. In EP 188188 such a device for spraying cooling liquid from nozzles of a cutting head is known in which the chisel of the cutting head itself actuate a valve and therefore a spraying of cooling liquid only takes place when the respective chisel, which is associated with the corresponding nozzle , is engaged. In order to be able to perceive a blockage of a nozzle in these cases, a throttle is switched in front of the nozzle, wherein sensors use the pressure difference of the space in front of the throttle relative to the space after the throttle as an indication of whether there is a blockage of a nozzle or not. The pressure in the space downstream of the throttle increases in the event of a blockage relative to the pressure in front of the throttle, so that at a given sufficiently small pressure difference can be concluded on a largely blockage of the nozzle. In addition to such relatively complex devices, it is known to arrange spray nozzles in nozzle sticks and to eject cooling liquid constantly through a plurality of such nozzles during the operation of a propulsion or extraction machine. In order now to monitor a sufficient effect of such spraying, has been proposed in DE 2915176 already downstream of the water spray nozzles a temperature-dependent resistor. The water jet emerging from the nozzles influences the temperature-dependent resistance, as a result of which a signal of this temperature-dependent resistance is used for the possibly necessary shutdown of the machine. However, this reference also refers to security problems which consist in the fact that the machine could still be put into operation, bypassing such simple control measures, and thus an incorrect operation takes place. Such incorrect operation could not last, if the permissible operation of the machine is exclusively dependent on the fact that the water supply is turned on. Namely, such an arrangement could allow operation even if one or more water nozzles are clogged or if one or more valves associated with the water nozzles remain closed because only the pressure is felt for control and even if the flow would be sensed instead of the pressure , a pipe break could lead to failure of the arrangement.

The invention now aims to provide a method of the type mentioned, in which an entire nozzle beam can be monitored effectively and incorrect operation can be avoided. In particular, the invention aims at avoiding malfunctions or shutdowns of the machine if the water pressure supply is not carried out with constant pressure. Monitoring systems where only one flow controller is manually set to a critical one Flow rate is set, which indicates the clogging of a nozzle, are highly error prone with fluctuating water pressure and lead to an uncontrolled control behavior, which in turn has relatively complex maintenance and adjustment work to avoid unintentional machine shutdown during operation.

To achieve this object, according to the invention, a monitoring method and a monitoring system for a monitoring device, e.g. a jetting beam for a cutting tool or a heap on the loading table created, which automatically adjust to the actual on-site conditions and ensure greater security for detecting the failure of a single nozzle.

For this purpose, the method mentioned in the introduction is characterized in that the pressure and the flow rate of the medium to be supplied to the spraying device are measured, that the measured values are fed to an evaluation circuit and with the desired characteristic curve measured for the spraying device for the dependence of their flow rates on the operating pressure of a error-free spraying device are compared and that deviations from the nominal characteristic of a fault-free spraying device are displayed and / or used as control signals for driving the tunneling and / or mining machine. The fact that not only flow rate measurements but also pressure readings are taken into the evaluation or regulation according to the invention and that a corresponding characteristic is determined according to the invention, which takes into account the pressure-dependent change in the flow rate, the possibility is created to specify such characteristics in the form of nominal characteristics and in one Comparator or an evaluation circuit to compare the actual measured values, which correspond to a defined point on this characteristic, with the characteristic curve. It he- Thus, if the pressure is subject to variations, the corresponding change in the flow rate in the time unit does not necessarily result in a shutdown, as long as the measured change remains within what would be termed the pressure-dependent change in flow rate per unit time. In order to ensure a certain tolerance with respect to a definite nominal characteristic which is not yet critical, the procedure according to the invention is advantageously such that the permissible deviations from the desired characteristic are stored as a characteristic field in the evaluation circuit, the characteristic field preferably being limited by characteristic curves which corresponds to a deviation of the measured values with less than one defective nozzle. In this way, a permissible operation results when a predetermined threshold is not exceeded, wherein a particularly high degree of accuracy can be achieved when in fact the characteristics of the individual nozzles are known, such characteristics usually to the factory specifications of the nozzles to count. The method is therefore advantageously carried out in such a way that the characteristic curves for determining the characteristic fields are determined as pressure-dependent flow rate characteristic curves for individual nozzles and calculated for the actual number of nozzles of the conditioning device, preferably the threshold value for the shutdown of a drive is set when a characteristic curve is reached, which corresponds to a deviation of the characteristic of the jetting device to the characteristic value of + 0.5 nozzles. The shutdown is thus carried out with certainty, if a nozzle fails, so that a high degree of operational reliability with significantly reduced possibilities of unintentional influence on the operational shutdown of the cutting motor is made possible.

In order to monitor the safe operation of the respective sensors during operation, it is advantageously possible to proceed in such a way that the

Sensors by recording characteristic curves with lowered operating pressure and comparison, these measured values are checked with previously measured nominal values.

In principle, in the case of the method according to the invention, too low a supply pressure can not ensure a sufficient minimum pressure for the flammability safety with methane outgassing and therefore the relevant safety regulations are not met. It can thus be selected as one of the limits, a corresponding lower limit for the supply pressure, with a rapid decrease in the supply pressure, for example, in the case of a hose break or closed supply line can be observed. Further cases of damage to be recognized relate to the fact that jets can be lost from the beam due to mechanical vibrations and, for example, a hose break after the flow sensor can also occur. A leakage in the pressure line after the flow sensor as well as heavily washed nozzles with no longer correct spray pattern have the consequence that the nozzle set must be replaced.

With the procedure according to the invention, however, it is also possible to determine in a particularly simple manner whether a nozzle is blocked. In these cases it is often sufficient to clean the nozzles, in which case if several nozzles have a smaller flow due to deposits, the entire nozzle set would have to be changed. Overall, these complex relationships make it possible to define a characteristic field as a permissible characteristic field within the recorded characteristic curves and that only the permissible characteristic field must be stored in the evaluation circuit and it must be checked whether the actual measured values lie within this permissible characteristic field move. Within the permissible range, the required minimum pressure and the minimum flow at minimum pressure are monitored, whereby the calculation of the characteristic curve is carried out continuously. If the following conditions a) minimum pressure, for example at least 11 bar b) Flow rate sensor measures more than minimum allowable flow c) Flow rate sensor measures smaller than maximum allowable flow rate and while ensuring that flow rate is greater than minimum flow rate for mimimum pressure, correct jet can be assumed. The mutual examination of the sensors by varying the water pressure can also be done during operation. If, when reducing the water pressure, the pressure and flow rate sensors behave according to the characteristic curve, the correct function can be assumed. Should the machine shut down in such a case, it means that a sensor would be defective.

The device according to the invention for carrying out this method is essentially characterized in that a pressure sensor and a flow rate sensor are provided for the medium to be supplied to the spraying device whose measured values are passed via signal lines to an evaluation circuit, that the evaluation circuit a memory for nominal characteristics of the pressure-dependent curve Contains flow rates of error-free spraying device and provides characteristic fields for the allowable deviation from the desired characteristic and that the evaluation circuit is connected to a display device and / or a control member of the drive of the tunneling and mining machine.

Overall, the device according to the invention and the method according to the invention have the advantage that manual adjustment work can be dispensed with and machine shutdowns, which are based solely on pressure fluctuations of the supply line and on influences which trigger such pressure drops, are largely avoided. It is also advantageous that the BedüsungsSystem can be operated at different pressures and in this way the water consumption and the dust deposition can be influenced without this leading to a malfunction of the device. The number of Overall, electronic surveillance elements can be significantly reduced and the risk of the monitoring system being manipulated by the operating personnel can be minimized.

The invention will be explained in more detail with reference to an embodiment schematically illustrated in the drawing. 1 shows a schematic view of the circuit arrangement according to the invention for the spraying, FIG. 2 shows a characteristic nozzle characteristic as used according to the invention, and FIG. 3 shows a diagrammatic representation of the switching logic.

In Fig.l is 1 schematically a nozzle for spraying a cutting drum, wherein the individual nozzles are designated 2. The pressure in the supply line of such nozzles is detected via the control line 3 and the pressure sensor 4. The medium is supplied to the nozzle blocks 1 and the nozzles 2 via a pressure reducing valve 5 and the line 6, in which a flow rate sensor 7 is turned on. However, the medium is now not only supplied via the line 8 to the nozzle sticks 1 but also via the line 9 to the nozzles of the loading table, in order to jet the heap and cool in this way. The motors to be controlled and, in particular, the cutting motor are schematically indicated by 10, the two loading motors being designated by 11. By evaluating the values of the flow rate sensor and the pressure sensor in more detail below, the cutting motor or the loading motors can be directly influenced.

The characteristic field that is correct for the determination of the operating parameter is represented as a nozzle characteristic in FIG. In Fig. 2, a graph showing a change in the flow rate per unit time from the input pressure for the entirety of the respective nozzles can be seen at 12. This characteristic curve 12 thus corresponds to the nominal value of the entire nozzle. If a nozzle is added or removed, the corresponding characteristic curve shifts upwards or downwards, the characteristic curve 13 corresponding to the ratios for n + 1 nozzles and the characteristic curve 14 to the ratios for n-1 nozzles. Between each of these two limit values, a fictitious characteristic curve 15 or 16 is computationally or graphically determined in the center, which corresponds in each case to the deviation by half a nozzle. The field delimited by the characteristic curves 15 and 16 can be designated as a permissible nozzle characteristic field and as long as the measured values are in the stated range, a correct function can be assumed. At the same time, however, a lower limit value must also be defined, which is determined by the coordinates of point 17 in the representation according to FIG. This point corresponds to the minimum flow rate and the minimum pressure for safe operation, which also results in shutting down of the engine (s) if these values are not reached. The permissible characteristic field is thus defined by the hatched area 18.

entsprechender Vergleich dieses Rechenwerts mit dem tatsächlichen vom Sensor ermittelten Wert für den Durchfluss führt nun zu einer logischen Abfrage des Kennlinienfeldes. Der Messewert des Durchflussmengensensors Q_Sensor soll oder

≥Q_Solιx n—J, wobei i = 1 und n = Anzahl der Düsen ist, sein,In Figure 3, the switching logic is now explained in more detail. The signals of the sensor inputs are referred to as P _sensor and Q _SensOr and serve on the one hand to control the minimum pressure or the minimum flow rate in the unit time and on the other hand, the calculation of the respective setpoint, which takes into account the pressure dependence of the flow rate. These

corresponding comparison of this calculated value with the actual value determined by the sensor for the flow now leads to a logical query of the characteristic field. The measured value of the flow rate _sensor Q _sensor should or

≥Q _Solι xn-J, where i = 1 and n = number of nozzles,

whereby the respective upper or lower limit of the characteristic field is queried. As long as the Q _sensor remains within the required range, the spray is fine and the machine can continue to operate. A crossing or an accident If this value is exceeded, this will result in shutdown and an error message.

darf die Maschine weiterbetrieben werden und die Bedüsung ist in Ordnung. Bei Unterschreiten des Sensorwerts für den Durch- fluss in der Zeiteinheit sowie bei einem Unterschreiten des Minimaldrucks wird eine Abschaltung vorgenommen und es erfolgt eine entsprechende Fehlermeldung. At the same time, the aforementioned control of the minimum pressure and the minimum flow rate leads to a corresponding query of the characteristic curves. If and the pressure value P _sensor ≥ the P _min , then

the machine may continue to operate and the spray is ok. If the sensor value for the flow in the unit of time falls short of the minimum pressure and if the minimum pressure is undershot, a shutdown is carried out and a corresponding error message is issued.

Claims

Patent claims: 1. A method for detecting clogging of Bedüsungs- devices on propulsion or extraction machines, characterized in that the pressure and the flow rate of the medium to be supplied to the metering device are measured, that the measured values supplied to an evaluation circuit and measured with the desired characteristic curve for the Dependence of their flow rates are compared by the operating pressure of a faultless spraying device and that deviations from the nominal characteristic of a fault-free spraying device are displayed and / or used as control signals for a drive of the tunneling and / or mining machine. 2. The method according to claim 1, characterized in that the permissible deviations from the nominal characteristic are stored as a characteristic field in the evaluation circuit. 3. The method of claim 1 or 2 _Λ characterized in that the characteristic field of characteristics is limited, which correspond to a deviation of the measured values at less than a defective nozzle. 4. The method of claim 1, 2 or 3, characterized in that the characteristics for determining the characteristic curves are determined as pressure-dependent flow rate characteristics for individual nozzles and calculated for the actual number of nozzles of the spraying device. 5. The method according to any one of claims 1 to 4, characterized in that the threshold value for the shutdown of a drive is set upon reaching a characteristic curve, which corresponds to a deviation of the characteristic of the spraying device to the characteristic value of + _ 0.5 nozzles. 6. The method according to any one of claims 1 to 4, characterized in that the sensors are checked by recording characteristics at reduced operating pressure and comparison these measurements with previously measured setpoints. 7. A device for carrying out the method according to one of claims 1 to 6, characterized in that a pressure sensor and a flow rate sensor are provided for the medium to be supplied to the spraying device whose measured values are passed via signal lines to an evaluation circuit that the evaluation circuit a memory for nominal characteristics contains the pressure-dependent profile of the flow rates of a fault-free spraying device and provides characteristic fields for the allowable deviation from the desired characteristic and that the evaluation circuit is connected to a display device and / or a control member of the drive of the tunneling and mining machine.