EP1251198A1 - Particle suction device for textile machines and method for monitoring it - Google Patents

Abstract

The dirt extraction system, for a textile machine, has a suction air flow passing constantly through a tube (12,14,16,18) during a trouble-free operation. The temperature of the tube wall is monitored at two points (20,24), and the sensor signals are compared and evaluated to determine if there is a fault in the working. A heater is at the first measurement point. The tube assembly has sections of brass and a plastics thermal insulation tube section.

Description

The invention relates to a textile particle suction device for Textile machines, in particular for circular knitting machines and a Method for monitoring such a device. Further The invention also relates to a circular knitting machine in which such a device is used.

Textile machines generate textile particles when different types. These particles can work severely impair the textile machine. Especially this is particularly pronounced in circular knitting machines, in particular Stocking machines. These machines create textile particles Leftover yarn, fluff and abrasion. As with circular knitting machines If the needles are particularly fine, there may be thread remnants or get lint in them, which ultimately leads to Major damage to the mechanics of the machine can result can.

To avoid this, the textile particles are constantly extracted. Pumps create a vacuum in a pipe or Hose system, of which one or more pipes are nearby of those places ends openly where the Textile particles are preferred. By the of the pumps generated vacuum is constantly sucked in air and with the Air particles drawn through the tube also become the textile particles carried.

It can be the case with such textile particle suction devices Disturbances come. In particular, larger particles can accumulate accumulate critical points in the pipe system and thus the suction resistance increase considerably, so that the cleaning function the device is reduced or even prevented. The result Conditional dangers are described above.

It is an object of the invention to provide a method for monitoring to provide a textile particle suction device with which as quickly as possible - a reaction within is required of less than 15 seconds - can be detected when a Malfunction occurs. This allows an immediate reaction for example, the textile machine is switched off immediately or generates an alarm signal.

According to the invention, a signal is first obtained which is from the temperature of the wall of a pipe through which in the undisturbed Condition air flows depending on. Based on this signal using an evaluation unit determines whether the device works undisturbed.

The invention takes advantage of the fact that the air flowing through the tube is in temperature exchange with the pipe wall. Will the pipe clogged, less or no air flows on the pipe wall over and this affects their temperature.

The temperature of the tube wall is then particularly high Presence of air flow through the tube depending if specifically a temperature difference between the pipe wall and the Air is generated. It is conceivable to constantly close the pipe wall cool, the air flowing through then for heating would worry. It is technically easier to use the pipe wall to heat a heater. Then air flows on the Pipe wall over, it is cooled, d. H. the pipe wall will heated less than the heater would allow. If a malfunction then occurs, the pipe is blocked more or less, less or no air flows on the pipe wall over and the pipe wall gets warmer.

In the simplest case, the pipe wall is separated from the heating device heated, e.g. B. constantly. The evaluation unit detects this Temperature signal at different times and evaluates the Temperature over time.

The simplest case is that the signal is the absolute temperature represents the pipe wall at a first position of the pipe. The criterion used by the evaluation unit for the determination A malfunction can then consist in that the Temperature of the pipe wall (or the signal representing it) is compared with a predetermined threshold. exceeds the temperature or the signal the threshold value, so malfunction is detected.

The method can be further developed such that a second signal is obtained, which corresponds to the temperature, which is in a place other than the first position, and that the evaluation unit based on a comparison of the first and of the second signal determines whether the device is undisturbed is working. The other location can be a second location on the pipe wall be thermally insulated from the first point of the pipe wall and is not heated by a heating element. The other The location can also be outside the pipe, it becomes the Outside temperature recorded. It is preferably provided that the the other location mentioned above (i.e. the second location) upstream the first position is arranged and the measurement in both Cases as close as possible to the inside of the pipe wall. As a result, temperature fluctuations in the environment, z. B. compensated for by starting the machine become.

The heating device heats the pipe wall at the first point in the simplest case constantly, so the evaluation unit can first signal or both signals at different times record, at these times, the comparison between the perform the first and the second signal and thus the time course evaluate.

According to a preferred embodiment of the invention, the time derivative in particular in the evaluation unit ("the differential") of the measured temperature as Function of time for the detection of trouble-free To evaluate operations. This is based on the knowledge that if a fault occurs, the measured temperature or the temperature difference measured in the above sense as Function of time in a characteristic way changes what in the evaluation unit in the form of empirically obtained in particular Evaluation algorithms can be considered. In a The evaluation unit determines a particularly advantageous embodiment the time derivative of the Temperature difference between the first (heated) and the second place. With undisturbed operation of the textile particle suction device the temperature is stabilized in the first place, and the temperature also remains in the second place constant or when the ambient temperature changes both temperatures increase equally. So that is Time derivative of the temperature difference equal to zero. If the time derivative exceeds a predetermined one Threshold, it means a sudden change in the Temperature difference, which usually only arises from that the air flow is interrupted or disturbed. Exceeding the threshold value therefore shows the malfunction on.

In the previously mentioned embodiments of the invention The first signal was representative of the process absolute temperature of the pipe wall at the first position. to Determining a temperature difference required one second signal.

However, it is also possible that the only signal, that is to say the first signal, only the temperature difference between the first digit and is played in another location. For example, this is the case when a thermocouple is used, the Ends in the first place and the other place. A resulting thermal voltage is a signal that shows the temperature difference represents.

Another embodiment of the method according to the invention consists in the fact that the first signal for the absolute Temperature of the pipe wall at the first position is representative, that a second signal is then additionally obtained, the the temperature difference between this point and one other, thermally insulated from the first position Represented place, especially on the pipe. In this case the second signal can be obtained by means of a thermocouple the ends of which are in the first place or the other place lie. The thermocouple (i.e. the temperature sensor) for the second signal in the airflow upstream with respect to arranged the temperature sensor for the first signal.

The determination of a malfunction by the evaluation unit (usually an evaluation computer) can be different To have consequences. For example, an alarm device can be used by the operator inform (acoustically and / or optically) or it can, e.g. B. if the evaluation unit is a special shows strong disturbance, i.e. a particularly high threshold as a criterion is exceeded, the textile machine automatically be switched off.

According to another aspect of the invention, a textile particle suction device provided for textile machines, by which a method according to the invention can be carried out.

In its simplest embodiment, the invention has Device a temperature sensor that the temperature at a first place of a pipe through which in undisturbed operation Air flows, measures, as well as an evaluation unit that measures the measured Evaluates temperature (based on a specified criterion) and thus determines if the operation of the device is undisturbed or is disturbed.

Here too, the first point of the tube is preferably heated, namely by means of a heating device, for example an um the corresponding part of the coiled heating wire. The temperature increase thus generated can be in the range of some Degrees Celsius move.

According to a preferred embodiment, there is a second temperature sensor provided the temperature at a second Location of the tube measures, the second location of the tube being thermal essentially decoupled from the first position of the tube (isolated), and the evaluation unit also the Evaluates the temperature at the second point of the pipe, d. H. of the second temperature sensor as well as the first temperature sensor Receives signals.

The two tube parts explained above are preferably (Pipe sections) in terms of dimensions, shape and material designed the same or at least approximately the same, since on this Way the effect of interference by a comparison method can be reduced. The pipe should be as possible be thin.

The thermal decoupling can be such that the first digit and the second digit on pieces of pipe from z. B. Metal located by a thermally insulating piece of pipe, preferably made of plastic, are separated from each other. To facilitate the temperature measurement, there is the first position (but preferably also the second position) a piece of pipe made of thermally highly conductive material, for example brass or a material with comparable thermal properties.

The pipe section where the first position is is preferably designed so that it has the lowest possible heat capacity has (per unit length), so that if the Air flow the temporal temperature differential large values reached. If the pipe piece is made of brass, you can this e.g. thereby achieve that the pipe section has a diameter from 0.5 to 2.5 cm and a tube wall thickness from 0.2 to 0.5 cm.

So that the temperature of the pipe sections is not affected by external air currents is influenced, they are generally preferred by one Protection tube surrounded and thermally insulated. The space between the protective tube and the pipe sections can be filled with air, is preferably potted with silicone.

According to a preferred embodiment, the evaluation unit designed to measure the difference between the two Determine and evaluate temperatures. The temperature sensors can be thermocouples. Thermocouples give an analog Signal off. The evaluation unit then preferably comprises one Analog-to-digital converter and a microprocessor, the real one Evaluation is therefore carried out digitally in the microprocessor.

Such a microprocessor in particular, but also others Evaluation units are suitable for the temporal course to record and evaluate each measured temperature and in addition in particular the derivation of the difference between to calculate and evaluate the two temperatures.

According to a further aspect of the invention, a textile machine comprises in particular a circular knitting machine, an inventive one Textile particle suction device, the on state the textile machine can be controlled by the evaluation unit is. The microcontroller in the evaluation unit can, for example via a cable (or infrared, ultrasound, or similar) give a signal to the on-off switch of the textile machine.

Likewise, according to a preferred embodiment, the evaluation unit received a signal from the textile machine which indicates whether the machine is e.g. B. in a working or Hibernation or a signal to what extent the suction explained above is activated. This Signal can have an adjustable effect Period of time to be delayed to non-stationary states of the Hide machine.

• Es wird eine thermische Messung des Luftdurchsatzes durchgeführt, die den Luftstrom nicht durch Querschnittsveränderungen im Rohr so beeinflußt, daß dadurch eine Beeinträchtigung des Luftstromes, z. B. durch sich an dieser Stelle ablagernde Textilpartikel, erfolgt;
• das Meßverfahren kann durch Auswertung von Temperaturen und zeitlicher Temperaturveränderung schnell auf Änderungen des Luftstromes reagieren;
• die Sensoren können aufgrund einer symmetrischen Anordnung Störeinflüsse eliminieren; und
• der Sensor kann aus extrem einfachen Bauteilen zusammengesetzt und damit kostengünstig hergestellt werden.

The measuring device characterized above with regard to important aspects is characterized in particular by the following features and advantages:

• A thermal measurement of the air throughput is carried out, which does not influence the air flow by changes in cross-section in the tube so that an impairment of the air flow, for. B. takes place at this point by depositing textile particles;
• the measuring method can react quickly to changes in the air flow by evaluating temperatures and changes in temperature over time;
• the sensors can eliminate interference due to a symmetrical arrangement; and
• the sensor can be assembled from extremely simple components and can therefore be manufactured inexpensively.

Figur 1

einen Querschnitt der erfindungsgemäßen Meßeinrichtung und

Figur 2

eine perspektifische Ansicht einer erfindungsgemäßen Meßeinrichtung.

Further advantageous embodiments of the invention will become apparent from the following description of a preferred embodiment of a measuring device to be installed in a textile particle suction device. The figures show:

Figure 1

a cross section of the measuring device according to the invention and

Figure 2

a perspective view of a measuring device according to the invention.

A measuring device 10 shown in FIGS. 1 and 2 can be in a textile particle suction device for a textile machine be installed, especially in a pipe in one Such suction device can be installed or on a such can be scheduled, or it can be done entirely replace. The air extracted by pumps then flows through the Operation of the suction device through four pipe sections 12, 14, 16 and 18, of which the pipe sections 12 and 16 are made of brass and the pipe pieces 14 and 18 made of plastic. The latter can be from be cut off with a plastic tube. In the figures the suction pipe is only shown for a short distance. It understands yourself that the pipe section 18 can be much longer and too a suction pump. The pipe section 12 can also be essential be longer than shown; it leads to the critical point the textile machine (not shown) on which the textile particles should be suctioned off.

At a first location 20 is an end of a thermocouple 22 attached to the pipe section 16. At a second point 24 correspondingly a second thermocouple 26 on the pipe section 12 attached. The first digit 20 and the second digit 24 are thermally insulated from each other because the pipe section 14 as Plastic hose is poorly heat-conducting.

The first pipe section 16 is heated by means of a heating winding 28, which is supplied with current via connections 30 and 32. The thermocouple 22 then outputs a thermal voltage that corresponds to the temperature T _{1 of} the first, heated pipe section 16, while the thermocouple 26 outputs a voltage that corresponds to the temperature of the second pipe section 12. So that these two temperatures are not influenced by air currents flowing past the pipe sections on the outside, the pipe sections 14, 16 and 18 are at least largely surrounded by a protective tube 34. The interior 36 between the wall of the protective tube 34 and the tube pieces 12, 14, 16 and 18 is potted with silicone, so that the entire element 10 is very stable. Here, a small part of the pipe section 12 protrudes from one end of the device 10. This open pipe section 12 can be inserted directly into the suction hose of a textile machine. The opposite piece of hose 18 can be plugged onto the coupling piece of the suction hose. The entire measuring device 10 can, however, be arranged anywhere in the textile particle suction device, in which case further tubes can be attached to the tube pieces 12 and 18.

In operation, the measuring device 10 works as follows:

The thermocouple 22 measures a thermal voltage that is dependent on the temperature at the first location 20 and the thermocouple 26 measures a thermal voltage that is dependent on the temperature at the second location 24. The thermal voltages are passed through low pass filters (not shown) to suppress noise and interference. They are then fed to an analog-to-digital converter (not shown), which outputs a digital signal corresponding to the thermal voltage to a microprocessor (not shown). Both thermocouples are connected in series and the temperature difference ΔT = T ₁ - T _{2 is} determined in this circuit.

If a current is now sent through the heating wire 28, then the pipe section 16 is heated and ΔT different from zero. flows Air in the direction of the arrow shown in Figure 1 above (or in reverse direction) through the element 10, the air flow cools the walls of the pipe section 16.

The power "S" per degree Celsius of temperature difference between the first and the second position is a measure of the air flow in the pipe. Neglecting parasitic heat losses results in S according to Eq. 1 in a simplified model of the electrical power L supplied to the heating wire 28, the heat capacity C _{p of} the pipe section 16, the temperature difference ΔT and its time derivative dΔT / dt, namely as follows: S = L - Cp · d .DELTA.T dt .DELTA.T

After a while of heating, an equilibrium is established so that dΔT / dt becomes zero. Then: S ∞ = L ΔT∞ where ΔT _{∞ is} the temperature difference in equilibrium.

A reference measurement when the heating is switched on allows the apparatus parameter C _p to be determined. When the heater is switched on, ΔT _o = 0. The result is: Cp = L d .DELTA.T dt 0

Then

As can be seen from equation (4), both ΔT and Derivation of ΔT according to the time to the air flow Performance per degree Celsius.

If an accident occurs, S suddenly becomes smaller or even zero.

If it becomes zero, it means that on the right Side of formula (4) the break in parenthesis must become 1 dΔT / dt is suddenly different from zero. Changes the time derivative of ΔT, then also changes ΔT self.

Both ΔT and its time derivative are continuously monitored in the microprocessor. If the derivative suddenly differs from zero and exceeds a threshold value dependent on L / ΔT, this means that the air flow flows weakly or no longer through the measuring device 10, which means an accident. Instead or in addition, it can serve as a criterion that the accident has occurred when ΔT has exceeded a certain threshold value, which is naturally slightly above ΔT _∞ , because if the air flow fails, the temperature difference due to the heating of the pipe section 16 is increased by the heating element 28 ,

Since the time derivative of the temperature difference, dΔT / dt, reacts particularly quickly to an accident, it makes sense to to use the threshold criterion regarding this quantity. On the other hand, the evaluation of ΔT is more reliable. Ideally both criteria can be combined. Like this in individual has to happen can by details of the construction of the depending on the pipe sections, thermocouples etc. used. Prefers are the threshold criteria empirically for a given Measuring device 10 determined. These empirical data are e.g. B. won so that a typical operation of a textile machine is simulated and the heating in the measuring device in operation is set. The temperatures mentioned are measured and tracked their timing. Then an accident occurs targeted with more or less severe blockage of the pipe are generated and depending on the degree of constipation occurring temperatures and temperature differences and you determined over time. The pipe becomes blocked brought to a state defined as a fault state becomes. The associated temperatures, temperature differences and time derivatives of the temperatures serve to Set up threshold criteria and in the microprocessor save. These saved quantities, if necessary with the addition of tolerances, serve later in real operation the device as a threshold criterion, d. H. the then continuously measured quantities are compared with this, to determine a malfunction.

If the microprocessor detects that a malfunction has occurred, so he gives z. B. a signal to a control device (not shown) the textile machine so that it is switched off becomes. This prevents textile particles such as yarn residues, Lint and abrasion damage the textile machine.

It is also possible to trigger an alarm in another way, so that the operating personnel take appropriate measures if necessary seizes without necessarily the operation of the Textile machine must be interrupted, provided the fault condition is recognized early.

The measuring device 10 described above has in particular the Advantage that the response time in the event of a total failure is very short, The textile machine is switched off within 15 seconds. Furthermore, the essential measuring elements are outside the pipe sections arranged so that the air flow through the measurement is not is hindered, in particular there are no installations on which lint can settle.

The measuring device 10 is also very simple, so that the Costs per monitoring point are low.

Claims (16)

Method for monitoring a textile particle suction device for a textile machine, the device sucking air through a pipe (12, 14, 16, 18) in the undisturbed state, and a signal dependent on the temperature of the tube wall at a first point (20) thereof is obtained and an evaluation unit is used to determine on the basis of the first signal whether the device is working undisturbed. Method according to claim 1, characterized in that the tube wall is heated at the first point (20) by means of a heating device (28) before the extraction or during the extraction of the first signal. Method according to Claim 2, characterized in that the evaluation unit detects the first signal at different times and evaluates the time profile. Method according to one of the preceding claims, characterized in that the first signal represents the absolute temperature (T ₁ ) of the tube wall at the first point (20) and evaluation unit preferably detects a malfunction when the temperature (T ₁ ) of the tube wall at the first digit (20) exceeds a predetermined threshold. Method according to one of Claims 3 or 4, characterized in that a second signal is obtained which represents the temperature (T ₂ ) which prevails at a second point (24) of the tube wall, which is from the first point (20) of the tube wall is thermally insulated (14), and that the evaluation unit uses a comparison of the first and the second signal to determine whether the device is working undisturbed, the first and second locations of the pipe wall being assigned to different sections of the pipe, and in particular the said sections of the pipe are designed the same. Method according to one of claims 3, 4 or 5, characterized in that the tube wall is heated at a first point (20) by a heating device (28), in particular continuously, and that the evaluation unit detects at least the first signal at different times and the Carries out a comparison between the first and the second signal for different times and evaluates the time course. Method according to Claim 6, characterized in that the evaluation unit determines the difference (ΔT) in the temperatures at the first (20) and the second point (24) from the comparison between the first and the second signal and then detects a malfunction when the latter Temperature difference (ΔT) exceeds a predetermined threshold. Method according to one of claims 3, 6 or 7, characterized in that the evaluation unit detects a malfunction using the time derivative of a temperature signal or the temperature difference. Textile particle suction device for textile machines, in particular for circular knitting machines, which sucks air through a tube (12, 14, 16, 18) in undisturbed operation, characterized by a Temperature sensor (22) which measures the temperature (T ₁ ) at a first point (20) of the tube and an evaluation unit that evaluates the measured temperature based on a predetermined criterion and thus determines when the operation of the device is disturbed. Apparatus according to claim 9, characterized by a heating device (28) which heats the first point (20) of the tube. Device according to one of claims 9 or 10, characterized by a second temperature sensor (26) which measures the temperature (T ₂ ) at a second location (24) of the tube, the second location (24) of the tube being thermal from the first location (20) of the pipe is decoupled (14), and the evaluation unit also evaluates the temperature (T ₂ ) at the second point of the pipe. Device according to claim 11, characterized in that the first point (20) and the second point (24) are located on pipe sections (16, 12) which are separated from one another by a thermally insulated pipe section (14,), preferably made of plastic. Device according to one of claims 11 or 12, characterized in that the first point (20) is located on a first pipe section (16) which consists of thermally conductive material, preferably brass. Device according to one of claims 11 to 13, characterized in that the evaluation unit is designed to determine and evaluate the difference (ΔT) between the two measured temperatures and, if appropriate, their time profile. Textile machine, in particular circular knitting machine, with a Textile particle suction device according to one of claims 9 to 14, wherein the on state of the textile machine by the Evaluation unit is controllable. Measuring device (10) for a textile particle suction device for textile machines, characterized by a first blank (16) with a first temperature sensor (22) which measures the temperature (T ₁ ) of the tube piece and through a second pipe section (12) with a second temperature sensor (26) which measures the temperature (T ₂ ) of the second pipe section.

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