EP0286950B1 - Cheminée d'alimentation pour machines de traitement de matière fibreuse - Google Patents

Cheminée d'alimentation pour machines de traitement de matière fibreuse Download PDF

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Publication number
EP0286950B1
EP0286950B1 EP88105423A EP88105423A EP0286950B1 EP 0286950 B1 EP0286950 B1 EP 0286950B1 EP 88105423 A EP88105423 A EP 88105423A EP 88105423 A EP88105423 A EP 88105423A EP 0286950 B1 EP0286950 B1 EP 0286950B1
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Prior art keywords
signal
filling height
level
forwarding
height
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German (de)
English (en)
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EP0286950A1 (fr
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Thomas Schenkel
Urs Stähli
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Maschinenfabrik Rieter AG
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Maschinenfabrik Rieter AG
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    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01G—PRELIMINARY TREATMENT OF FIBRES, e.g. FOR SPINNING
    • D01G23/00—Feeding fibres to machines; Conveying fibres between machines
    • D01G23/02—Hoppers; Delivery shoots

Definitions

  • the invention relates to a hopper for a fiber processing machine, e.g. a card or a cleaning machine in the blow room of a short batch spinning mill.
  • a fiber processing machine e.g. a card or a cleaning machine in the blow room of a short batch spinning mill.
  • this arrangement should enable an uninterrupted fiber flow from the feed shaft into the feed shaft.
  • the production set by the operator is set too high, so that the slow speed is nevertheless too fast and the delivery of the flakes in the feed chute has to be stopped by an overfill protection system, i.e. the conveyance of the flakes in the feed chute is discontinuous, which is known to be undesirable and leads to strong impacts on the cotton-forming material column (upsets).
  • a further arrangement for the delivery of fibers or flakes in a filling shaft is shown and described in the French patent application with the publication number 2524500, in which an essentially vertically arranged series of sensors scans the filling height in the fiber feeding shaft and, according to the height, an analog signal to one Outputs controller by means of which the speed of a pair of feed rollers is controlled.
  • the pair of feed rollers feeds a corresponding amount of flakes via pneumatic transport into the aforementioned feed shaft.
  • a fluctuating fill level in a feed chute causes a different density in the area of the feed rollers at the lower end of the feed chute, which is either disadvantageous or has to be corrected via a further control or regulation.
  • our invention also has a series of essentially vertically arranged sensors for monitoring the fill level in a feed chute, it has the task of keeping the density of the fiber column in the feed chute as constant as possible.
  • the invention is therefore characterized procedurally by the characterizing part of the first method claim and device-wise by the characterizing part of the first device claim.
  • the device has a number of sensors, each of which is able to determine the presence of the flowable material in a specific working range of the sensor.
  • the device contains an interrogation device in order to interrogate the sensors as to whether material is present in their work areas or not.
  • a specific sensor in this row can then represent a setpoint for the level in use.
  • the current material level is determined. Any instantaneous deviation of the current level from the target height is thus given by the distance between the current level and the sensor representing the target height.
  • the distance between each two adjacent sensors can be the same along the row, but in a preferred variant this distance is chosen to be smaller in the vicinity of the sensor representing the setpoint and larger in the areas further away from the setpoint.
  • This last arrangement gives a more precise level detection and possibly also a smaller "level hysteresis" in the vicinity of the setpoint, while the whole row of sensors still covers a sufficiently large level range without a large number of sensors (with corresponding additional devices, as will be described below) desire.
  • the number of sensors in the row will depend on usage conditions, but for a hopper on a fiber processing machine, 6 to 10 sensors will normally meet the requirements.
  • the sensors can be light barriers. Each light barrier can be designed as either a one-way barrier (without reflector) or a two-way barrier (with reflector).
  • the sensors can be switched individually or in groups in order to sense the presence of material in their respective work areas, so that cross talk between the sensors is avoided. The sequential switching of the sensors can be controlled by the interrogation device.
  • the interrogation device can be arranged in such a way that it regularly repeats a specific interrogation cycle, with each sensor being interrogated within each cycle. The results for each cycle are then sent to an evaluation, where a possible deviation of the current level from the target level is determined. The size of this deviation is made available to the controller as a suitable signal.
  • the evaluation can be designed in such a way that it can react differently to a change in level indicated by the sensors in one direction than to a change in level indicated by the sensors in the other direction.
  • the evaluation can be arranged in such a way that, under predetermined circumstances, it immediately and fully passes on an "apparent" level change in one direction (eg downward), while only delaying an "apparent” level change in the other direction (eg upward) and / or to a reduced extent in a predetermined manner. In this way, "deceptive effects" can be reduced.
  • the first sensor that shows no material in its working area can be accepted as determining for the apparent current level.
  • a signal representing the deviation can be processed by the controller according to a predetermined control function in order to generate an output signal supplied by the controller.
  • This variable output signal can be used as a reference variable (setpoint) for serve another controller, which regulates the funding directly.
  • a feed roller or a pair of feed rollers
  • the controller can then regulate the speed of the feed roller.
  • the said control function can preferably be changed as a function of the size of a detected deviation between the desired and actual heights of the fiber column.
  • the entire measuring range defined by the height measuring device can e.g. be divided into two or more (preferably four) zones, a respective control function being determined for each zone.
  • each control function is preferably a so-called PI function.
  • the filling shaft 20 shown in FIG. 1 will only be described briefly, since it was explained in detail in the "mittex" publication mentioned above is.
  • the shaft 20 is supplied with fiber flakes from machines upstream in the blowroom line via a pneumatic feed channel (not shown). Flakes are excreted from this channel in a separating head 22, so that they flow downward together with transport air into a so-called feed shaft 24.
  • a wall 26 of the feed shaft is formed by a perforated plate, so that the transport air can flow through this wall 26 into a calming space 28 and from there an exhaust air housing 30.
  • the flakes themselves cannot pass through the holes in the perforated plate and form a wadding (not shown) in the feed shaft 24 above a pair of feed rollers 32.
  • the feed rollers 32 can be driven by a motor 34 in order to deliver material from the wadding formed in the feed shaft 24 to an opening roller 38 driven by the motor 36.
  • the feed shaft therefore serves as a reserve-forming shaft.
  • the material conveyed by the feed rollers 32 and opening roller 38 falls as smaller flakes or as individual fibers into a so-called feed chute 40, where it forms a fiber or flake column (not shown) above a pair of draw-off rollers 42. Material from the lower end of this column, not shown, can be supplied through the take-off unit 44 comprising the rollers 42 to the feed cylinder 46 of a card, not shown.
  • the filling shaft 20 shown in FIG. 1 is designed in particular for card feeding, an essentially identical shaft can be used for feeding fiber material to other machines in a blowroom line.
  • the shaft parts are mounted in a housing 48 in the arrangement already described.
  • a lower light barrier 50 and an upper light barrier 52 are provided to regulate the column height in the feed shaft 40.
  • the intended mode of operation of these light barriers in cooperation with the motor 34 has already been indicated in the introduction to this patent specification and has been completely described in the article from the specialist press mentioned at the outset, so that a further description can be dispensed with here.
  • the known height control system of FIG. 1 is to be replaced by the new system of FIG. 2.
  • the feed chute 24, feed chute 40, feed roller pair 32 and opening roller 38 shown in FIG. 2 remain unchanged and are therefore provided with the same reference numerals as in FIG. 1.
  • the drive motor 34A for the feed roller pair 32 must enable a constant or continuous speed regulation, instead of simply switching between slow and fast speed in the arrangement according to FIG. 1.
  • a height measuring element 54 which is described in more detail below, is now provided, which outputs signals delivers to an evaluation 56.
  • a controller 58 receives output signals from evaluation 56 and responds to control the speed of motor 34A.
  • a control loop is thus formed, which can have the form shown in FIG. 3.
  • the control path of the control loop includes the feed shaft 24 with the lower end of the wadding 60 (FIG. 2) and the feed shaft 40 with the fiber or flake column 62 (FIG. 2), the height, i.e. the position of the uppermost surface 64 of the column 62 in the feed chute 40 should be regulated.
  • a material outflow MFa takes place from the lower end of the shaft 40 and cannot be influenced by the control loop itself.
  • a material flow MFe takes place, which takes place within the control loop and can be controlled by the control loop via the control device (ie via the actuator in the form of the feed roller pair 32 and the actuator in the form of the motor 34A) in order to keep the column height in the feed chute 40 as constant as possible.
  • the measuring device of the control loop is formed by the height measuring element 54 attached directly to the feed shaft 40 together with the associated signal evaluation 56.
  • the evaluation 56 contains a first unit 56A, which emits a signal h representing the current current column height (the column level) and a second unit 56B, which carries out a comparison between this actual height and a predetermined target height, by a possible height deviation generating signal e.
  • controller 58 in FIG. 2 is formed by two elements, namely by a microprocessor 58A and a motor controller 58B.
  • the latter must be adapted to the motor 34A and can be of an ordinary construction, so that another Description can be omitted here.
  • the microprocessor 58A processes the signal e in accordance with a predetermined control algorithm in order to output a signal n representing the setpoint for the motor controller 58B.
  • FIGS. 4 to 7 Examples of a height measuring device for use in a shaft arrangement according to FIG. 2 will now be described with reference to FIGS. 4 to 7. As a first step, the position of the height measuring device in relation to the feed chute 40 will be explained with reference to FIG.
  • each light barrier is designed as a two-way device, with a transmitter-receiver unit in a housing 54A on one side of the feeder shaft 40 and a reflector 54B on the opposite side Manhole side.
  • the light barriers of the device 54 could, however, be formed as one-way devices so that each contains a transmitter element on one side of the shaft and a receiver element on the opposite side of the shaft, the reflector 54B then being omitted.
  • the housing 54A in FIG. 4A is mounted on a transparent plate 66, and the latter is mounted in the side wall 68 of the shaft so that the light beams of the barriers can be transmitted across the width of the shaft to and from the reflector 54B.
  • the individual sensors (not shown in FIG. 4) are arranged in a vertical row.
  • a predetermined position within this row (preferably approximately halfway between the upper and lower ends thereof) represents a target level SN (a target height).
  • This target level SN is preferably as far as possible from the take-off rollers 42 (FIG. 1) (column height as large as possible) ) without taking the risk of overfilling the shaft 40 to the opening roller 38.
  • a suitable distance between the nominal level SN and the outer surface of the opening roller 38 lies in the range 200 to 300 mm, the said outer surface containing all rotating parts of the opening roller 38 (including the clothing).
  • the target level SN can be clearly defined or determined. Determining the current level (represented in simplified form by surface 64 in FIG. 2) is a relatively complicated operation, which requires a determination process. Certain problems with this determination can be seen from the representation of the fiber column 62 in FIG. 4A and the schematic representation of the newly arriving flakes 70.
  • the uppermost surface of column 62 will never form a horizontal plane, and new flakes 70 will normally be present above this column surface and at the same time within the total measuring range of the height measuring device 54. It will therefore be clear, firstly that the device 54 cannot sense a "more precise” or “absolute” current level (because there is no such level) and secondly that any "deceptive effects" must be taken into account, which come from newcomers nearby existing flakes can be caused on the column surface.
  • FIG. 5 shows a vertical row of n sensors which have been numbered successively from bottom to top.
  • each sensor is shown as a one-way light barrier, with respective transmitter elements S1 to Sn and corresponding receiver elements E1 to En.
  • FIG. 5 shows the two lowest light barriers 1 and 2 and the three uppermost barriers n-2 to n
  • the target height or target level SN (FIG. 4A) lies somewhere between the barriers 2 and n-2.
  • the fiber column should therefore normally cover the receivers E1 and E2 with respect to the correspondingly assigned transmitters S1 and S2, while the receivers EN-2 to En should be left blank with the correspondingly assigned transmitters Sn-2 to Sn.
  • one or the other or each light beam from these upper light barriers can be replaced by new ones Fiber flakes 70 (Fig. 4A) are interrupted.
  • An imaginary "work area” is defined for each sensor by the path of the light beam from the transmitter to the receiver (of the same sensor). If there are flakes in this "work area", the light beam is interrupted.
  • the sensors can be queried continuously or at any intervals for their respective "states", i.e. whether their respective light beams have been interrupted (state - covered) or not (state - free). With such a detection, the column height must be lower than the working area of the first free barrier from the lower end of the row.
  • the position of the adjacent, deeper, covered sensor can be referred to as the "apparent" current level.
  • each bar represents the result of a query cycle
  • the bar height indicates the number of light barriers that are covered by fiber material, as seen from the bottom end of the row, ie between the bottom end of the row and the first free light barrier.
  • the vertical axis of the bar chart is divided according to the sensor numbering, whereby the same distances between the sensors are assumed.
  • the column height determined by the evaluation is not necessarily the same as the apparent column height represented by the bar height.
  • the processing of the height signals within the evaluation depends on the direction of any changes in height.
  • the resulting column heights are indicated in Fig. 6 by the dashed line.
  • the determined value is set equal to the apparent value.
  • both values are given with four "units" (sensors covered from the bottom end of the row).
  • the apparent value drops to two units. From a consideration of FIGS. 4A and 5, it will be clear that the current level can in no case be above the apparent level.
  • the determined value also corresponds to the apparent value in the second query cycle.
  • the apparent value increases to five units. It becomes clear from the consideration of FIGS. 4A and 5 that the current level can very well be below the apparent level, so that an increase in the apparent level between two successive query cycles cannot be accepted as "valid" without further ado.
  • the evaluation therefore passes on an increase, but not fully, but to a reduced extent according to a predetermined function.
  • the apparent level goes up further, which causes a further increase in the dashed line (and the correspondingly determined value for the column height).
  • the apparent level comes down slightly again without bringing the bar chart and the dashed line together again. The latter happens in the sixth polling cycle when the apparent value falls below the determined value again. The implementation of this step will be described below in connection with FIG. 8.
  • the query cycles 7 to 10 show that periodic, smaller fluctuations in the column height are practically not passed on by the evaluation, since they are "smoothed" by the delay emanating from the determination function. As shown for the last three polling cycles in FIG. 6, the apparent value is obtained from the determined value after a certain time delay if it remains at the top.
  • FIG. 6 shows that a step-like or step-like increase in the signal at the input of the evaluation causes a step-like increase in the level (represented by the signal h).
  • this result can be achieved by means of a digital low-pass filter, the filter characteristic being set in such a way that a step-shaped Increasing the input signal only after a predetermined number of polling cycles (time delay) is fully reflected in the determined level (in FIG. 6, after 4 polling cycles - see cycles 11, 12 and 13).
  • the signal x only accepts discrete values (corresponding to a number of sensors), the signal h can assume any values caused by the filtering.
  • FIG. 7 shows further details of a height measuring device which can work according to the system described in connection with FIGS. 5 and 6.
  • the device contains eight one-way light barriers with transmitters S1 to S8 and respective corresponding receivers E1 to E8.
  • the light barriers are operated in multiplex mode so that they are switched on in sequence, with each light barrier being switched on once within a single polling cycle.
  • the period of the polling cycle is so short that movements of falling flakes within a polling interval can be neglected.
  • the light barriers are switched on in order to avoid mutual interference. If such mutual interference can be avoided in other ways (e.g. by suitable modulation of the light signals or by color filtering), the light barriers can be switched on at least in groups at the same time or even continuously.
  • the polling interval is determined by the multiplexer 72. In the case of simultaneous activation, a polling interval could be determined differently, e.g. by a suitable clock.
  • the status signals from the receivers E1 to E8 are transmitted via a Data line 74 read into a shift register 76, the read operation being controlled by signals on a trigger line 78 from multiplexer 72.
  • a Data line 74 read into a shift register 76
  • the read operation being controlled by signals on a trigger line 78 from multiplexer 72.
  • the state data can be read out by an output gate 84 by means of a suitable strobe signal on line 82, so that the corresponding information is still available to them
  • Descriptive evaluation unit 56A (Fig. 3) can be forwarded via a connector 86 (Fig. 7).
  • the evaluation unit 56A is shown again schematically in FIG. 8, the scheme being chosen less to represent reality than to explain the operations carried out.
  • Unit 56A includes an input stage 88 which receives the data from shift register 76 (Fig. 7). From this, the unit 56A derives the apparent level by determining the number of light barriers between the lower end of the row and the first free light barrier and supplies a corresponding signal x to an output stage 90.
  • the signal x can therefore represent discrete values from 0 to 8.
  • the lower end of the row ie sensor no. 1 (and not the desired height) serves as the reference level, everything below this reference level being regarded as "0".
  • the signal x thus corresponds to the distance between this reference level and the lowest point within the measuring range, where no material is detected, for example if sensor 1 itself does not detect any material determines, the signal x remains at "0" -
  • the signal x corresponds to the number (L-1), where L is the number of the first free light barrier from the lower end of the row.
  • the output stage 90 processes the signal x into an output signal h, the type of processing depending on the development of the signal x over time (on its "history").
  • the direct forwarding is represented by the signal path (bypass) 91, while a second signal path comprises a low-pass filter 89.
  • a controllable switch 87 sends the signal x to either the bypass 91 or the filter 89.
  • the switch 87 is controlled by a comparison element 93, which compares the instantaneous signal x with the signal h just delivered (a memory - not shown - for the signal h can be between the filter 89 and the comparison element 93 are switched on).
  • switch 87 is controlled so that signal x is provided to bypass 91. Conversely, if element 93 determines that signal x is higher than previously output signal h, switch 87 is controlled so that signal x is provided to filter 89.
  • the evaluation unit 56A thus receives a signal from the device 54 which corresponds to the apparent level determined by the device 54.
  • the unit 56A supplies a signal h which corresponds to the determined level.
  • the output signal h of the unit 56A changes as a function of the signal supplied by the device 54, the function itself being changeable depending on the "behavior" of the input signal. In the given example, this function depends on how the instantaneous “signal level” of the input signal (in discrete values 0 to 8 of the signal x) behaves in relation to a previously determined output signal h.
  • the function can be adjusted between two forms (low pass filtering and unchanged forwarding) according to the input signal, i.e. in one case the function corresponds to a 1: 1 reproduction of the input signal.
  • the invention is not restricted to the variant listed as an example.
  • it could prove advantageous to filter both a decreasing and an increasing input signal, but with different cutoff frequencies.
  • this change can be carried out by an operation other than filtration.
  • empirical values for the "real" meaning of "level jumps" can be determined by tests and entered in the programming of the evaluation.
  • "average values" of some combined query cycles could be passed on.
  • Changes in the processing function could e.g. caused by changes in the input signal alone, rather than by changes in the input signal compared to the output signal (in which case the filtering must be changed accordingly).
  • the main difference from the example given would be seen in the behavior of the system when (slowly) descending from a peak of the apparent level, e.g. in cycles 4, 5 and 6 in FIG. 6, in that the descending tendency alone is sufficient to bring the unchanged forwarding of the input signal back into effect.
  • the function can take more than two forms, and additional forms would have to bring significant benefits to justify the complications involved.
  • the optimal evaluation can be determined empirically (by considering the system's response to various level fluctuations). In any case, the evaluation should recognize a rising tendency in its input signal and only pass it on modified.
  • the signal h the determined height shown is compared with a predetermined target height and an output signal e is supplied in order to represent any deviations.
  • This output signal comprises two components, namely a directional component ⁇ and a variable.
  • the signal is processed in accordance with the control algorithm of the microprocessor 58A, as will be described below in connection with FIGS. 9 and 10. For the time being, however, certain possible operating states in the controlled system will be dealt with.
  • the control according to this invention works preferably at least during normal production operations without operator intervention. This means that the regulation is not provided with any information about the target production of the card (or other machines to be supplied). The regulation must therefore also function if the supply shaft 40 (FIG. 1) is completely empty at the start of its work (start of work). Furthermore, the control not only absorbs general fluctuations during normal operation, but also compensates for the effects of a new adjustment of card production carried out by the operator.
  • control algorithm itself is determined as a variable function of the deviation from the target level.
  • the change in the control algorithm can be carried out in stages, so that the measuring range defined by the height measuring device is divided into several zones, each zone being assigned to a predetermined control algorithm.
  • the control algorithms of neighboring zones are always different, but zones that are not adjacent to one another can be assigned to the same algorithm.
  • a corresponding division of the measuring range is shown schematically in FIG. 9.
  • the vertical line corresponds to the entire measuring range covered by the height measuring device.
  • the cross lines NAZ max and NAZ min correspond to the upper and lower limits of a "normal working zone", ie during normal operation, level fluctuations within this zone must be expected.
  • a first ("normal") control algorithm is assigned to this zone.
  • the section above the normal working zone (NAZ) is referred to as the upper working zone (OAZ) and is assigned to a second control algorithm in order to break down the accumulated flakes more quickly.
  • An overfill protection device (not shown) is provided above or at the upper end of the work zone OAZ in order to switch off the supply of flakes if the control system can no longer counteract a further increase in the column height.
  • the cross line NP represents a "relative zero point", so that a lower working zone UAZ is defined between point NP and point NAZ min.
  • This working zone UAZ is also assigned to a control algorithm which differs from the algorithm of the zone NAZ.
  • the algorithm of the lower work zone can be equated with that of the upper work zone or can differ from the latter.
  • LZ below the relative zero point NP there is an "idle zone” (LZ) which is assigned to a further algorithm which differs from that of the lower working zone UAZ.
  • the current column height should only be in (or below) the idle zone LZ when the shaft is to be filled (new start of work) or to be emptied.
  • the corresponding control algorithm can be determined in such a way that the shaft is filled up particularly quickly if the flake feed is regulated according to this algorithm. In order to let the shaft run empty, the flake feed can be switched off, so that the control loop is no longer able to compensate for the material flow from the lower end of the shaft by feeding from above.
  • the cross line SN represents the target level, which of course lies within the normal working zone NAZ.
  • Box 100 in FIG. 10 represents an initialization step which must be carried out when the shaft or the control system is switched on again in order to determine the initial states.
  • This step automatically sets a predetermined speed of the motor 34A (e.g. 30 to 50% of the maximum speed of the motor).
  • the system immediately proceeds to determine the actual height (the actual level) represented by box 102.
  • the step shown in box 104 it is then determined whether the actual height is greater than the maximum height (NAZ max) of the normal working zone, i.e. whether the actual height is in or above the upper working zone OAZ.
  • NAZ max maximum height
  • the deviation signal is processed according to a first control algorithm A1, as indicated in box 106 in FIG. 10. This step determines a new base speed (target speed) of engine 34A and the corresponding data is stored, the final step being represented by box 108.
  • the stored value is now output in the form of a target speed signal N (box 110).
  • the loop leads back to the new determination of the actual height (box 102), or to the steps indicated by the dashed lines, which will be dealt with later in this description.
  • step 114 first determines whether the actual height is within the normal working zone (between the normal maximum and minimum heights NAZ max or NAZ min ) lies. In this case, the deviation signal is processed according to a second control algorithm A2 (box 116) in order to determine the new basic speed, after which the loop continues through steps 108, 110 and 112 described above.
  • step 118 determines whether the actual height is within the lower working zone UAZ, i.e. lies between the normal minimum height NAZ min and the zero point NP. In this case, the deviation signal is processed according to a third control algorithm A3 (box 120), after which the processor proceeds to steps 108, 110, 112. If it is determined by step 118 that the actual altitude lies below the zero point (i.e. inside or below the idle zone LZ), the deviation signal is processed according to a fourth control algorithm A4 (box 122) in order to determine the new basic speed.
  • the control parameter FN within the normal working zone NAZ is preferably independent of the size of the deviation e, so that the components K and Tn are determined as constants for this zone.
  • the respective Control parameters F0, FU proportional to the deviation e can be set by adapting the components K and Tn accordingly, ie in these zones K and / or Tn is a function of e.
  • the target speed N is no longer determined by processing the deviation signal e, but directly from a characteristic curve Fl (t).
  • the symbol t indicates that the target speed N is a function of time, so that the longer the actual height remains below the zero point NP, the higher the target speed N is set.
  • the characteristic curve itself can be made dependent on the basic speed and / or the sinking speed, e.g. the slope of the characteristic can be changed as a function of one or both of these parameters.
  • the microprocessor switches on a time measurement method when the actual height drops from the lower working zone UAZ to the idling zone LZ, and the determination of the target speed N is made dependent on the subsequent measured time according to the characteristic curve Fl (t). If this time measurement method is not stopped within a predetermined interval by the return of the actual height to the lower working zone UAZ, the microprocessor issues an error message "shaft empty", after which the card can be switched off.
  • a corresponding time measurement method can be used to determine the sink rate mentioned by determining the expiry time for lowering the actual height through predetermined intervals within the lower working zone, after which, for example, the slope of the characteristic curve can be adjusted accordingly.
  • the creep speed SK can be replaced by the last stored value of the normal basic speed Sn. This measure enables a malfunction to be eliminated, which could otherwise be caused by foreseeable operating conditions outside the normal machine sequence.
  • FIG. 11 which provides a so-called disturbance variable feed-in, serves a similar purpose.
  • the control loop shown in Fig. 3 influences only the speed of the feed rollers 32, which should lead to a change in the material flow MFe. However, this material flow is dependent on other sizes, for example on the density of the material stored in the shaft 24.
  • the lift of the feed rollers 24 can be measured by suitable means (not shown), a corresponding signal S (FIG. 11) can be generated and combined with the signal generated by the microprocessor 58A in order to give a corrected nominal value N. .
  • the signal i representing the lift (FIG. 11) can be processed, for example, by forming the reciprocal value (box 126 in FIG.
  • the output signal of the device 126 can be adapted by a proportional factor in the device 128 to form the signal S.
  • Signal S can then be multiplied by the output of microprocessor 58A. If a linearization function can be built into the formation of the signal S, the multiplication point 130 (FIG. 11) can be replaced by an addition point.
  • FIG. 12 shows the preferred arrangement of eight light barriers in order to optimally cover an entire measuring range.
  • This total area is again represented by a vertical scale, as in FIG. 9.
  • the length of this scale has been given as 150mm as an example, but the arrangement is not limited to this example.
  • the cross lines on this scale represent the positions of the individual light barriers, these barriers being identified from number one to one after the other as numbers 1 to 8.
  • light barrier No. 4 represents the target height or the target level, which for example is 95 mm from the lower end of the scale (0mm) can be set.
  • A in this example of 10 mm
  • Zone LZ - below sensor 1 Zone UAZ - sensor 1 to below sensor 2
  • Zone NZ sensor 2 to below sensor 7
  • Zone OAZ - sensor 7 to below sensor 8 (Overfill protection - sensor 8)
  • the proposed arrangement aims for optimal use of a limited number of sensors.
  • the goals mentioned could of course also be achieved by increasing the number of sensors, but this would considerably increase the overall effort (not only for the sensors themselves, but also for the corresponding downstream elements for signal processing).
  • the invention is not restricted to the details of the illustrated embodiments. In particular, it is not dependent on the use of light barriers. Other sensors, e.g. Ultrasonic transmitter / receiver units can be used. Where the actual height is to be determined by light radiation (which in this context includes the infrared and UV ranges), it is not essential to the invention to use "discrete" signals (generated by individual sensors). The actual height could e.g. can be determined by a so-called image analysis of the entire measuring range. Where individual sensors are needed, the arrangement (array) can be more complex than the simple series of the example described. Of course, the complexity must have a corresponding advantage, e.g. bring higher accuracy by determining an average value.
  • the sensors of the height measuring device should have the same sensitivity as far as possible.
  • the device In connection with a shaft depth (distance transmitter-receiver or transmitter - reflector) of approx. 190mm, the device can be arranged so that a thirty percent gray filter does not interrupt the beam path (minimum range of 350mm).
  • Each receiver unit can be equipped with its own amplifier and threshold switch.
  • the determined height values of the described versions are digital values, i.e. the system can only take into account predetermined, coded height values. However, they are also discontinuous values because they are determined according to a periodically repeated query cycle. If the sensors are switched on continuously, which requires an adapted evaluation, continuous digital values can be determined accordingly and taken into account by the controller.
  • Pneumatic sensors could be used as a further possibility, e.g. in the shaft wall.
  • the air flow through small nozzles could be used to determine the actual height.
  • FIG. 12 again represents a hardware solution, whereas in today's practice a software solution in the programming of a microprocessor would be preferable.
  • Fig. 13 shows time delay elements V1 to Vn between the inputs E1 to En (only three inputs shown) and an evaluation stage 88A which performs the same operation as the input stage 88 of the variant of Fig. 8, namely the determination of the number of light barriers between the lower one Row end and the lowest free light barrier in the row.
  • Each element V1 to Vn is assigned a respective redirection U with two switches S, with each switch S reacting to a signal change in the sense of "exemption" of the corresponding light barrier in such a way that the signal comes from the respective output of the shift register 76 via the respective redirection U.
  • the evaluation stage 88A is passed on, ie without delay.
  • the switches S react in such a way that the signal is passed from the respective output of the shift register 76 to the respective delay element V1 to Vn, and then only after the predetermined delay time has elapsed the evaluation level 88A is forwarded.
  • Each element V1 to Vn can be formed as a counter, the counter being prompted by a signal change in the sense of a cover for counting clock pulses and only emitting an output signal when a predetermined number of counting pulses is registered have been.
  • the elements V1 to Vn may have different time delays, shorter delays (approx. 1 second) close to the target level and longer delays (2-3 seconds) towards the end of the row being advantageous.
  • An “overfill protection” can be provided in that a “shaft vol” signal (all light barriers covered) triggers a stop signal after a time delay predetermined by an element US. If the "shaft vol” signal disappears from the output of stage 88A within this delay, the element US is reset and no stop signal is output.
  • a zone of the measuring range (Fig. 9/10) can therefore be assigned two (or more) different control algorithms, one taking effect when the level falls and the other when the level rises.
  • the decrease or increase in the level can be determined by comparing the currently determined value with a previously stored value and the corresponding control algorithm can be selected.
  • Above the target level it is possible to react relatively strongly to an increasing level (reducing the speed), but to reacting to a decreasing level relatively weakly (reducing the speed).
  • a rising level can be relatively weak, a falling level relatively strong, in both cases in the sense of an increase in speed be reacted to.
  • a base speed for the feed roller (s) No can accordingly be defined for the target level.

Landscapes

  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Preliminary Treatment Of Fibers (AREA)

Claims (19)

  1. Procédé permettant de surveiller la hauteur de remplissage (nommée également niveau) d'un silo d'alimentation d'une machine de traitement de fibres, dans lequel la hauteur de remplissage est tâtée par un nombre prédéterminé de capteurs, disposés essentiellement en verticale, et dont les signaux sont évalués pour commander un moyen de transport de fibres servant à transporter les fibres dans le silo d'alimentation,

    caractérisé par le fait
    qu'une hauteur prescrite de remplissage est donnée, et que l'analyse des signaux cités et ensuite la commande du moyen de transport de fibres se font de telle manière que la hauteur prescrite de remplissage est essentiellement maintenue.
  2. Procédé selon revendication 1,

    caractérisé par le fait
    que les signaux de capteurs (E₁-En) sont évalués en un signal de niveau unique (h, h₁) qui est comparé avec la hauteur prescrite prédéterminée de remplissage.
  3. Procédé selon revendication 1,

    caractérisé par le fait
    que la capacité de transport des moyens de transport de fibres est commandée en fonction de la direction de mouvement de ladite hauteur de remplissage par rapport à la valeur prescrite de la hauteur de remplissage.
  4. Procédé selon revendication 1,

    caractérisé par le fait
    que la capacité de transport des moyens de transport de fibres est commandée en fonction de la distance existant entre la hauteur de remplissage et la hauteur prescrite de remplissage.
  5. Procédé selon revendications 2 et 3,

    caractérisé par le fait
    que les signaux de capteurs (E₁-En) (figure 8) sont évalués en un signal de niveau primaire (x) (également nommé comme étant le signal de niveau apparent) qui est comparé avec la hauteur prescrite de remplissage comme signal filtré de niveau (h) lorsque la hauteur de remplissage augmente, et directement comme signal de niveau actuel (h) lorsque la hauteur de remplissage diminue.
  6. Procédé selon revendications 2 et 3,

    caractérisé par le fait
    que les signaux individuels de capteurs (E₁-En) (figure 13) sont évalués avec retardement lors d'un niveau montant, et directement lors d'un niveau descendant, en un signal de niveau actuel (h₁), lequel est comparé avec la hauteur prescrite de remplissage.
  7. Procédé selon revendication 1,

    caractérisé par le fait
    que, en plus, des rouleaux alimentaires (32), pouvant être pressés l'un contre l'autre, sont utilisés comme moyen de transport de fibres, et la capacité de transport est commandée en fonction de la course des rouleaux alimentaires (32).
  8. Procédé selon revendication 4,

    caractérisé par le fait
    que les hauteurs de remplissage sont subdivisées en zones supérieures et inférieures par rapport à la hauteur prescrite de remplissage, et que lesdites distances résultent de ces zones.
  9. Procédé selon revendication 8,

    caractérisé par le fait
    que la capacité de transport par zone est commandée à l'aide d'un algorithme de régulation prévu pour cela.
  10. Dispositif servant à surveiller une hauteur de remplissage (nommée également niveau) d'un silo d'alimentation d'une machine de traitement de fibres, comprenant
    - un nombre prédéterminé de capteurs définissant un champ de mesure et disposés essentiellement verticalement sur une paroi ou près d'une paroi du silo d'alimentation, et qui délivrent des signaux correspondants servant à évaluer la hauteur de remplissage,
    - une commande servant à recevoir et traiter lesdits signaux en un signal de commande utilisé pour commander la capacité de transport d'un moyen de transport de fibres servant à transporter les fibres dans le silo d'alimentation,

    caractérisé par le fait
    - qu'une hauteur prescrite de remplissage (SN) prédéterminée est donnée à l'intérieur du champ de mesure,
    - que la commande comprend des moyens (figure 7) servant à déterminer l'endroit où se trouve la hauteur de remplissage à l'intérieur du champ de mesure, et que ces moyens délivrent un nombre de signaux (80) correspondants à la hauteur de remplissage,
    - que la commande comprend en plus des moyens (figures 3, 8 et 13) servant à recevoir les signaux des moyens cités auparavant (figure 7) et à les évaluer en un signal dit de hauteur actuelle de remplissage (h, h₁) qui est comparé avec la hauteur prescrite de remplissage (SN) dans une unité de comparaison (56B) appartenant à la commande, et à produire un signal de commande (e), ainsi
    - que la commande comprend un régulateur (58) qui module la capacité de transport du moyen de transport de fibres (32) en fonction du signal de commande (e) cité auparavant.
  11. Dispositif selon revendication 10,

    caractérisé par le fait
    que le champ de mesure est divisé en zones (figure 9), et que lesdits moyens de commande (figure 7) déterminent l'une de ces zones dans laquelle se trouve la hauteur de remplissage.
  12. Dispositif selon revendication 11,

    caractérisé par le fait
    que lesdits moyens (figures, 3, 8 et 13) constatent en outre, si la hauteur de remplissage est en train de monter ou de descendre à l'intérieur desdites zones.
  13. Dispositif selon revendication 11,

    caractérisé par le fait
    que le champ de mesure comprend une zone normale de travail (NAZ), à l'intérieur de laquelle se trouve la hauteur prescrite de remplissage (SN), ainsi qu'une zone voisine supérieure (OAZ) respectivement une zone voisine inférieure (UAZ).
  14. Dispositif selon revendication 13,

    caractérisé par le fait
    que le champ de mesure comprend une autre zone (LZ) située en dessous de ladite zone inférieure (UAZ).
  15. Dispositif selon revendication 13,

    caractérisé par le fait
    que le régulateur (58) est prévu de telle sorte que la commande des moyens de transport de fibres (32) est interrompue lorsque la hauteur de remplissage a atteint l'extrémité supérieure de la zone supérieure (OAZ).
  16. Dispositif selon revendication 10,

    caractérisé par le fait
    que les distances entre les capteurs (E₁-En), dans la zone de la hauteur prescrite de remplissage (SN, sont les plus petites, et qu'elles s'agrandissent au moins en allant vers une extrémité (de préférence vers les deux extrémités) du champ de mesure.
  17. Dispositif selon revendication 10,

    caractérisé par le fait
    que le moyen de transport de fibres est composé de deux rouleaux alimentaires (32) pouvant être pressés l'un contre l'autre, et que la commande comprend une unité de compensation de perturbation (126, 128, 130) qui transforme la course d'un des rouleaux alimentaires, s'éloignant de l'autre rouleau alimentaire, en un signal (s) qui est inversement proprotionnel par rapport à la course, et qui multiple ce signal (s) avec le signal du régulateur (58A).
  18. Dispositif selon revendication 12,

    caractérisé par le fait
    que les moyens (figure 8), servant à déterminer si la hauteur de remplissage est en train de monter ou de descendre, comprennent un étage d'entrée (88) qui reçoit les signaux (80) donnés par ledit moyen (figure 7) et les évalue en un signal de niveau (x) appelé "apparant", et comprend en outre un élément comparateur (93) qui compare un signal de niveau prédécent (h) appelé "actuel" avec le signal de niveau suivant (x), et qui veille à ce que le signal suivant (x) passe à travers un filtre (89) lorsque la hauteur de remplissage est montante, ou qu'il contourne le filtre (89) par un By-pass (91) lorsque la hauteur de remplissage est descendante, afin d'être transmis comme signal de niveau "actuel" (h) à une unité de comparaison (56B) appartenant également au moyen, dans laquelle le signal (h) est comparé avec la hauteur prescrite de remplissage (SN) et qui produit un signal de commande (e) pour le régulateur (58).
  19. Dispositif selon revendication 12,

    caractérisé par le fait
    que les moyens (figure 13), servant à déterminer si la hauteur de remplissage est en train de monter ou de descendre, comprennent une unité de retardement (V₁-Vn) par signal capteur (80) ainsi qu'un By-pass (U) par unité de retardement (V₁-Vn), et un interrupteur (S) situé au début et à la fin du By-pass (U), et où les interrupteurs sont dimensionnés de telle sorte que, lors d'une position dite libre du capteur correspondant (E₁-En), un signal (80) est transmis via le By-pass (U) vers une unité d'évaluation (88A), et lors d'un soi-disant recouvrement du capteur correspondant (E₁-En), un signal (80) est transmis via l'unité de retardement (V₁-Vn) vers la même unité, afin de former un signal de niveau "actuel" (h₁) qui va être comparé avec la hauteur prescrite de remplissage (SN), après quoi un signal de commande (e) pour le régulateur (58) sera produit.
EP88105423A 1987-04-13 1988-04-06 Cheminée d'alimentation pour machines de traitement de matière fibreuse Expired - Lifetime EP0286950B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH145587 1987-04-13
CH1455/87 1987-04-13

Publications (2)

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EP0286950A1 EP0286950A1 (fr) 1988-10-19
EP0286950B1 true EP0286950B1 (fr) 1991-11-27

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ID=4210865

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EP88105423A Expired - Lifetime EP0286950B1 (fr) 1987-04-13 1988-04-06 Cheminée d'alimentation pour machines de traitement de matière fibreuse

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US (1) US4939816A (fr)
EP (1) EP0286950B1 (fr)
JP (1) JPS63270816A (fr)
DE (1) DE3866405D1 (fr)
ES (1) ES2028925T3 (fr)
IN (1) IN171263B (fr)

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DE3913997A1 (de) * 1989-02-14 1990-08-23 Rieter Ag Maschf Dosierverfahren und -vorrichtung zur abgabe vorgebbarer mengen von faserflocken
FR2654441B1 (fr) * 1989-11-13 1992-06-05 Schlumberger Cie N Chargeuse pour l'alimentation d'une carde par une nappe de fibres textiles la plus reguliere possible.
US5405052A (en) * 1993-12-09 1995-04-11 Sawyer, Iii; Miles G. Bottled-water dispenser with ice maker and cooler
DE102005040399A1 (de) * 2005-08-25 2007-03-01 Maschinenfabrik Rieter Ag Flockenbeschickungssystem
DE102010005196A1 (de) * 2010-01-21 2011-07-28 Hubert Hergeth Differentialspeisung
US20130134188A1 (en) * 2010-05-28 2013-05-30 Yoshino Kogyosho Co., Ltd. Cartridge-type dispenser

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Also Published As

Publication number Publication date
ES2028925T3 (es) 1992-07-16
IN171263B (fr) 1992-08-29
DE3866405D1 (de) 1992-01-09
JPS63270816A (ja) 1988-11-08
US4939816A (en) 1990-07-10
EP0286950A1 (fr) 1988-10-19

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