SE2330242A1 - Hood adjustment assembly and method for adjusting a position of a hood on a dryer cylinder - Google Patents

Abstract

The present invention relates to a hood adjustment assembly comprising a hood (11), a first gap sensor (21) and a second gap sensor (22), a hood gap adjuster (12) and a hood gap controller (30) comprising processing circuitry (31) configured to- receive a first input signal (SI) from the first gap sensor (21) and a second input signal (S2) from the second gap sensor (22), - determine whether a first criterion for a desired hood gap is fulfilled,- if the first criterion is not fulfilled, determine a desired adjustment of the hood (11),- generate a control signal (C) that is configured to cause the hood gap adjuster (12) to apply the determined desired adjustment, and wherein the hood gap adjuster (12) is further configured to- receive said control signal (C) from the processing circuitiy (31), and- move the hood (11) to adjust the hood gap (hg) based on said control signal (C).The invention also relates to a computerized method, a non-transitoiy computer-readable storage medium and a manufacturing method.

Description

TECHNICAL FIELD The present invention relates to the field of paper manufacture and in particular to adjustment of a hood on a dryer cylinder for drying a paper Web.

BACKGROUND Within the field of paper manufacture, a pulp is used to form a paper Web that is transported through a series of treatment steps aiming to form and dewater the Web to produce a paper. Such paper may be any kind of paper such as tissue, paper or board.

Some treatment steps include drying of the paper Web on a dryer cylinder Where the paper Web is subjected to heat in order to remove moisture. In some applications, a hood may be arranged on the dryer cylinder and held With a desired hood gap that must be large enough to prevent the hood from touching the paper Web and causing damage or rupture. The purpose of the hood is to provide additional drying of the paper Web by combining the heat from the dryer cylinder With a heating medium such as hot air being applied to the paper Web inside the hood.

One known problem is that the hood gap may change during operation of the paper machine, both due to components of the hood and dryer cylinder expanding When subjected to heat over long periods and due to fiber buildup from the paper Web. To ensure that damage to the paper Web is avoided, the hood gap is often kept large, but this renders the drying less energy efficient than desired.

There is therefore a need for improving operation of the hood for the dryer cylinder to avoid damage to the paper Web While at the same time enhancing energy efficiency.

SUMMARY The object of the present invention is to eliminate or at least to minimize the problems discussed above. This is achieved by a hood adjustment assembly, a hood adjustment system, a computerized method for adjusting a position of the hood, and a method for manufacturing a hood adjustment assembly according to the appended independent claims.

The hood adjustment assembly comprises a hood configured to be mounted in connection with a dryer cylinder to form a hood gap between the dryer cylinder and the hood, the hood extending in a first direction from a first end to a second end. The hood adjustment assembly also comprises a first gap sensor configured to measure or detect a width of the hood gap at a first position of the hood, and a second gap sensor configured to measure or detect a width of the hood gap at a second position of the hood. Also, the hood adjustment assembly comprises a hood gap adjuster configured to adjust the hood gap by moving the hood in relation to the dryer cylinder, and a hood gap controller comprises processing circuitry. The processing circuitry is configured to receive a first input signal from the first gap sensor and a second input signal from the second gap sensor, said first and second input signals being indicative of the measured or detected hood gap at the first position and second position, respectively, - determine, based at least on said measured or detected hood gap at the first position and said measured or detected hood gap at the second position whether a first criterion for a desired hood gap is fulfilled, - if the first criterion is not fulfilled, determine a desired adjustment of the hood, and - generate a control signal that is configured to cause the hood gap adjuster to apply the determined desired adjustment.

Furthermore, the hood gap adjuster is configured to receive said control signal from the processing circuitry, and to move the hood to adjust the hood gap based on said control signal.

Suitably, the first position of the hood is at the first end and the second position of the hood is at the second end. Thereby, the hood gap is detected or measured at both ends and the hood can be adjusted to ensure that the position of the hood is suitable at both ends. Since it is important to eliminate the risk of contact between the hood and the paper Web, it is particularly advantageous to ensure that factors such as e. g. an asymmetrical buildup of fibers on the hood do not cause the hood gap to become too small at one end of the hood gap assembly. Also, by measuring or detecting at both ends, it can be ensured that an excessively large gap that Would be disadvantageous from an energy efficiency standpoint is avoided.

In some embodiments, the first position of the hood and the second position of the hood are instead at the first end, and the first position and the second position are separated from each other in a second direction that is perpendicular to the first direction. Thereby, the hood gap can be measured in more than one position at the first end. lf the hood gap should be too small or too large in one of these positions, the hood can be adjusted accordingly.

Suitably, the hood adjustment assembly comprises at least one additional gap sensor configured to measure or detect a width of the hood gap at an additional position of the hood, and the processing circuitry is configured to - for each additional gap sensor, receive an additional input signal from the additional gap sensor, said additional input signal being indicative of the measured or detected hood gap at the additional position, and - determine, based also on said measured or detected hood gap at the additional position whether the first criterion for the desired hood gap is fulfilled.

Thereby, measurements or detections of the hood gap at various positions along the hood can be made and the adjustment of the hood can be determined to ensure that the hood is brought into a position that is advantageous along the entire hood. ln some embodiments, the hood gap adjuster comprises a first end gap adjuster configured to adjust the hood gap at the first end of the hood and a second end gap adjuster configured to adjust the hood gap at the second end of the hood. The processing circuitry is then configured to - determine the desired adjustment of the hood as a first end adjustment and a second end adjustment, and - generate the control signal as a first end control signal that is configured to cause the first end gap adjuster to apply the determined first end adjustment and a second end control signal that is configured to cause the second end gap adjuster to apply the determined second end adjustment.

Thereby, the hood gap can be adjusted individually for each end of the hood. This is particularly advantageous since it allows for adjusting the hood to a position that ensures a good fit of the hood over the dryer cylinder and allows each end of the hood to be placed in a highly beneficial position.

Suitably, the first gap sensor and the second gap sensor, and optionally also the third gap sensor, are optical sensors. Thereby, a convenient and reliable type of sensor are provided and allows for a direct measurement of the hood gap at each position. The optical sensors may be arranged on the hood or on another structure that is connected to the hood or that is separate from the hood.

In some embodiments, the hood adjustment assembly comprises reference markings connected to the hood, and the first sensor and second sensor, and optionally also the third sensor, are configured to measure or detect the width of the hood gap by detecting the reference markings. Thereby, the hood gap can be detected or measured by sensors that are arranged directly on the hood or on an extended component or separate component of the hood adjustment assembly. This decreases the risk of damage to the sensors or of the sensors being blocked by fibers from the paper Web, to ensure a stable and reliable operation With low maintenance of the sensors.

Suitably, the hood gap adjuster comprises an inclined guide on Which the hood rests and also comprises an adjuster that is configured to push the hood along the inclined guide in response to the control signal. Thereby, the position of the hood is adjusted in a reliable and convenient Way with excellent control over the precise position of the hood so that very small adjustrnents can be made in a highly accurate manner.

The present invention also encompasses a hood adjustment system comprising a first hood adjustment assembly according to the invention Wherein the hood is a wet-end hood for a dryer cylinder. The hood adjustment systern also comprises a second hood adjustment assembly according to the invention Wherein the hood is a dry-end hood for a dryer cylinder. Thereby, both a wet-end hood and a dry-end hood for a dryer cylinder are adjusted according to the invention to ensure that the hood gap is suitable for the drying operation of the paper Web. This is advantageous When seeking to avoid both that the paper Web is damaged during drying and an excessive energy consumption due to a large hood gap. The system of the invention thus ensures a stable and efficient operation When drying a paper Web.

The invention also comprises a Computerized method for adjusting a position of a hood on a dryer cylinder, the method comprising - receiving, in processing circuitry, a first input signal from a first gap sensor and a second input signal from a second gap sensor, said first and second input signals being indicative of a measured or detected hood gap at a first position and second position of a dryer hood, respectively, determining, in processing circuitry, Whether a first criterion for a desired hood gap is fulfilled based at least on said measured or detected hood gap at the first position and said measured or detected hood gap at the second position, determining, in processing circuitry, a desired adjustment of the hood if the first criterion is not fulfilled, and generating, in processing circuitry, a control signal that is configured to cause a hood gap adjuster to apply the determined desired adjustment.

The method suitably also comprises receiving, in processing circuitry, an additional input signal from each of at least one additional gap sensor, said additional input signal being indicative of the measured or detected hood gap at each additional position of the hood, determining, in processing circuitry, Whether the first criterion for the desired hood gap is fulfilled based also on said measured or detected hood gap at each additional position.

Also, the method may comprise determining, in processing circuitry, the desired adjustment of the hood as a first end adjustment and a second end adjustment, and generating, in processing circuitry, the control signal as a first end control signal that is configured to cause a first end gap adjuster to apply the determined first end adjustment and a second end control signal that is configured to cause a second end gap adjuster to apply the determined second end adjustment.

In some embodiments, the first criterion for the desired hood gap is that the determined hood gap is above a predetermined minimum hood gap. Thereby, adjusting the hood gap adjuster so that the hood gap fulfils the first criterion ensures that damage to the paper Web due to contact between the hood and the paper Web is avoided.

In other embodiments, the first criterion for the desired hood gap is that the determined hood gap is Within a predetermined hood gap range. Thereby, adjusting the hood gap adjuster so that the hood gap fuliils the first criterion ensures that damage to the paper Web due to contact between the hood and the paper Web is avoided, and also ensures energy efficiency since an excessively large hood gap is avoided.

In yet other embodiments, the first criterion for the desired hood gap is that the determined hood gap is below a predetermined maximum hood gap. Thereby, adjusting the hood gap adjuster so that the hood gap fulfils the first criterion ensures that the process of drying the paper Web between the dryer cylinder and the hood is energy efficient and that excessive energy use is avoided.

The invention also relates to a non-transitory computer-readable storage medium storing instructions Which, When executed by processing circuitry of a hood gap controller of a hood adjustment assembly for adjusting a position of a hood on a dryer cylinder, cause the hood adjustment assembly to: - receive, in processing circuitry, a first input signal from a first gap sensor and a second input signal from a second gap sensor, said first and second input signals being indicative of a measured or detected hood gap at a first position and second position of a dryer hood, respectively, - determine, in processing circuitry, Whether a first criterion for a desired hood gap is fulfilled based at least on said measured or detected hood gap at the first position and said measured or detected hood gap at the second position, - determine, in processing circuitry, a desired adjustment of the hood if the first criterion is not fulfilled, and - generate, in processing circuitry, a control signal that is configured to cause a hood gap adjuster to apply the determined desired adjustment.

Suitably, the non-transitory computer-readable storage medium further stores instruction which, when executed by the processing circuitry, cause the hood adjustment assembly to perform the method steps of any embodiment of the invention.

The invention also comprises a method for manufacturing a hood adjustment assembly. This method comprises providing a hood suitable for mounting in connection with a dryer cylinder to form a hood gap between the dryer cylinder and the hood, wherein the hood extends in a first direction from a first end to a second end. The method also cornprises providing a first gap sensor configured to measure or detect a width of the hood gap at a first position of the hood, providing a second gap sensor configured to measure or detect a width of the hood gap at a second position of the hood, providing a hood gap adjuster configured to adjust the hood gap by moving the hood in relation to the dryer cylinder, and providing a hood gap controller comprising processing circuitry. Furthermore, the processing circuitry is configured to receive a first input signal from the first gap sensor and a second input signal from the second gap sensor, said first and second input signals being indicative of the measured or detected hood gap at the first position and second position, respectively, - determine, based at least on said measured or detected hood gap at the first position and said measured or detected hood gap at the second position whether a first criterion for a desired hood gap is fulfilled, - if the first criterion is not fulfillecl, determine a desired adjustment of the hood, - generate a control signal that is contigured to cause the hood gap adjuster to apply the determined desired adjustment, and Wherein the hood gap adjuster is further configured to - receive said control signal from the processing circuitry, and - move the hood to adjust the hood gap based on said control signal.

Many additional benefits and advantages of the present invention Will be readily understood by the skilled person in view of the detailed description below. DRAWINGS The invention Will now be described in more detail With reference to the appended drawings, Wherein Fig. 1 discloses a planar view from a tending side of a hood adjustment system comprising two hood adjustment assemblies according to the present invention; Fig. 2 discloses a planar view from the side of a hood adjustment assembly; Fig. 3a discloses a planar view from the side of a first embodiment of a sensor of the hood adjustment assembly; Fig. 3b discloses the sensor of Fig. Sa taken along the line B-B of Fig. 3a; Fig. 4a discloses a planar view from the side of a second embodiment of a sensor of the hood adjustment assembly; Fig. 4b discloses the sensor of Fig. 4a taken along the line D-D of Fig. 4a; Fig. Sa discloses a planar view from above of a first embodiment of the hood of the hood adjustment assembly; Fig. 5b discloses a planar view from above of a second embodiment of the hood of the hood adjustment assembly; Fig. 6a discloses a perspective view of a hood gap adjuster of the hood adjustment assembly; Fig. öb discloses schematically the hood gap adjuster with the first guide and the first roll of the hood in a planar view from the side; Fig. 7 discloses schematically the controller of the hood adjustment assembly operatively connected to sensors and hood gap adjuster; Fig. 8 discloses schematically operation of the Sensors, processing circuitry and hood gap adjuster of the hood adjustment assembly; Fig. 9 discloses schematically steps of the method according to a first embodiment of the invention; and Fig. lO discloses schematically other embodiments of the method.

All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate the respective embodiments, whereas other parts may be omitted or merely suggested. Any reference number appearing in multiple drawings refers to the same object or feature throughout the drawings, unless otherwise indicated. DETAILED DESCRIPTION The present invention relates to assembly, system and method for adjusting a hood in a drying step of a paper machine. The paper machine as such will not be disclosed in detail and does not form part of the present invention; rather, the invention is suitable for use in any kind of paper machine where a dryer cylinder is used to dry a paper web and where said dryer cylinder is arranged with a hood. Typically, the hood is used to preserve heat emitted form the dryer cylinder during operation and also for circulating hot air to improve drying and lower the moisture content of the paper web. The paper machine itself may be used for manufacturing any kind of paper, tissue or board. The dryer cylinder itself may be any type of dryer such as a TAD (through air dryer) cylinder or a Yankee cylinder.

As used herein, the term "operatively connected" is to be understood as parts of the invention being connected electronically (ie. so that signals can be transmitted and/or received through a wire or through a wireless connection) and/ or parts of the invention being connected mechanically so that a movement or force can be transmitted from one part to the other.

The term "tending side" as used herein is the side of a paper machine from which the paper machine is controlled, whereas the other side is denoted as a "drive side".

The term "wet-end" is to be understood as the end where the moisture content of the paper web is higher, whereas the term "dry-end" means the end where the moisture content is lower. Thus, when two hoods are applied on a dryer cylinder, the paper web passes the wet-end hood before it reaches the dry-end hood.

When various embodiments are described herein, it is to be understood that features from any of the embodiments may freely be incorporated into any of the other embodiments where technically feasible and as long as such a combination is not explicitly stated as unsuitable or undesirable. Hood adjustment assembly and hood adjustment system embodiments Fig. 1 discloses a planar view from the tending side of a hood adjustment system 100 comprising two hood adjustment assemblies 10 according to a first embodiment of the present invention. Of the two hood adjustment assemblies 10, one is a wet-end assembly W and the other a dry-end assembly D, but their features are similar or identical and what is said below of any hood adjustment assembly 10 is to be understood as applicable to both the wet-end assembly W and the dry-end assembly D. In any paper machine, the hood adjustment assembly 10 according to the present invention may be applied in only one of the hoods or may be applied in both and thus form the system 100 of two hood adjustment assemblies 10.

The hood adjustment assemblies 10 each comprise a hood 11 that extends from a first end 11A to a second end 11B in a first direction D1 that is a 11 cross-machine direction, i.e. a direction that is perpendicular to a transport direction of the paper web (see Fig. 5) when the hood 11 is mounted in the paper machine. The hood 11 is configured to be mounted in connection with a dryer cylinder 200 as is well known within the art. Typically, the hood 11 is mounted to cover the dryer cylinder 200 at least partly so that the paper web transported on the dryer cylinder 200 is covered by the hood 11. Between the hood 1 1 and the dryer cylinder 200, a hood gap hg is formed.

The hood 1 l is held at each of the first end 11A and the second end 11B by a first guide 14 and a second guide 15, of Which the first guide 14 may be an inclined guide and the second guide 15 may be a horizontal guide. The purpose of the guides 14, 15 is for the hood 11 to rest on them, typically by rolls 16, 17 of the hood ll being arranged on the guides 14, 15 so that the hood 1 1 can slide on the guides 14, 15 When adjusted or opened. A hood gap adjuster 12 is arranged in connection with the first guide 14 so that adjusting the hood gap hg is performed by moving the hood 11 by pushing the roll 16 along the first guide 14. This will be described in more detail below with reference to Fig. 6. lt is advantageous for the second guide 15 to be a horizontal guide, since this enables a secure holding of the hood.

Fig. 2 discloses the hood adjustment assembly 10 in more detail, showing a first gap sensor 21 that is configured to measure or detect a width of the hood gap hg at a first position P1 of the hood 11. The invention also includes a second gap sensor 22 (see Fig. 5a-5b) that is configured to measure or detect a width of the hood gap at a second position P2 of the hood 11. Additional sensors may also be included as will be explained further below. The sensors 21, 22 are suitably optical sensors, but other types of sensors are also possible within the scope of the invention.

Fig. 3a-3b disclose one embodiment of the first gap sensor 21 configured to measure or detect the hood gap hg directly, i.e. by the first gap sensor 21 being arranged on the hood 11 facing the dryer cylinder 200 and arranged to detect or measure the distance from the first gap sensor 21 to a surface of the dryer cylinder 200. The first gap sensor 21 is shown with a wire 32 that provides a connection to the controller 30 and the processing circuitry 31 12 comprised therein, but alternatively the connection between the first gap sensor 21 and the controller 30 can be Wireless. Suitably, the first gap sensor 21 is arranged in a recess or cutout in the hood 11 to allow the first gap sensor 21 to protrude from the hood 11. ln the embodiment of Fig. 3a- 3b, the first gap sensor 21 is held to be flush With a surface llC of the hood 11, but in other embodiments the first gap sensor 21 can be held so that a distance from the first gap sensor 21 to the dryer cylinder 200 is larger than the hood gap hg. Insulation 33 is suitably provided for the first gap sensor 21 to prevent heat from affecting and possibly damaging the first sensor 21.

Fig. 4a-4b disclose another embodiment of the first gap sensor 21 in Which the first gap sensor 21 is instead held by a frame 34 to extend from the hood ll. This is advantageous in preventing damage to the first gap sensor 21 and also to prevent blockage of the first gap sensor 21 by fibers from the paper Web adhering to the sensor 21 during use. In Fig. 4a-4b, reference markings 220 are provided on a machine frame 210 that is connected to the hood 11 and that has a surface With the reference markíngs 220 that can be related to a position of the dryer cylinder 200. In some embodiments, the first gap sensor 21 and the reference niarkings 220 are held flush With the surface of the hood 11 and the surface of the dryer cylinder 200, respectively, but in other embodiments they may be held at other positions and the resulting hood gap hg may be determined by the processing circuitry based on the measured or detected hood gap hg from the first gap sensor 21. For this embodiment, the position of the first gap sensor 21 and the reference markings 220 may also be reversed so that the first gap sensor 21 is arranged on the machine frame 210 and the reference markings 220 on the frame 34. One particular advantage of providing the first gap sensor 21 according to this embodiment is that maintenance and replacement of the first gap sensor 21 is facilitated since it is easily accessible from outside the hood 1 1.

What is said above for the first gap sensor 21 is equally applicable for the second gap sensor 22 and also for any additional sensors 23 used With the present invention. The sensors 21, 22, 23 may be similar or identical, or may 13 alternatively differ from each other as long as they are able to measure or detect the hood gap hg and as long as they can be operatively connected to the processing circuitry 31 so that signals indicative of the measured or detected hood gap can be sent.

When the hood adjustment assembly 10 is in use in a paper machine comprising the dryer cylinder 200, the hood gap hg between the dryer cylinder 200 and the hood 11 must be sufficiently large to allow the paper web to be transported on the dryer cylinder 200 without touching the hood 11 to avoid damage or breakage of the paper web. The hood gap hg should also not be excessively large since the energy efficiency of the hood ll would othervvise be undesirably low and increase the energy use and thereby the cost of producing the paper. Typically, a desired hood gap is a preset value or range and may comprise a minimum hood gap to avoid damage to the paper, a maximum hood gap to avoid energy losses, or a range comprising both a minimum and maximum hood gap. During use, the hood gap varies both due to buildup of fibers from the paper web on the dryer cylinder or on the hood, and due to thermal expansion of the dryer cylinder and of the hood when used at elevated temperatures. Such thermal expansion increases from the start of the machine to a time when a maximum expansion is reached and is then maintained until the machine is shut down or until the operational temperature is changed. Based on the desired hood gap, a first criterion is determined (typically preset but in some embodiments based on operational parameters such as temperature and operation time and/ or on parameters of the hood and the dryer cylinder as such). As long as the first criterion is fulfilled, i.e. as long as the detected or measured hood gap hg is within the range of the desired hood gap, above a minimum hood gap or below a maximum hood gap, the first criterion is fulfilled and no adjustment of the hood 11 is needed. When the first criterion is not fulfilled, an adjustment of the hood is required to amend this.

Thus, the invention also comprises a hood gap controller 30 (see Fig. 7) that in turn comprises processing circuitry 31 and that is operatively connected to the sensors 21, 22 and to the hood gap adjuster 12. The processing 14 circuitry 31 is configured to receive a first input signal S1 from the first gap sensor 21 and a second input signal S2 from the second gap sensor 22, said first and second input signals S1, S2 being indicative of the measured or detected hood gap hg at the first position P1 and second position P2, respectively.

Fig. 5a discloses one embodiment where the first gap sensor 21 and second gap sensor 22 are provided at the first end 11A of the hood, i.e. on the tending side of the hood adjustment assembly 10. The first position Pl and the second position P2 are separated from each other in a second direction D2 that is perpendicular to the first direction D1, i.e. that is in the machine direction when the hood adjustment assembly 10 is mounted in connection with the dryer cylinder 200 of the paper machine.

Placing the sensors 21, 22 at the same end of the hood 11 allows for a reliable determining of the hood gap hg and ensures that adjusting the hood 1 1 will result in the desired hood gap hg. Additional gap sensors 23 may also be provided, both at the first end 11A and at the second end llB, and in some embodiments a measured or detected hood gap by some or all of the additional gap sensors 23 are used for determining Whether the first criterion is fulñlled. This will be described further below with reference to the method embodiments. The additional gap sensors 23 may be any suitable number of additional gap sensors 231, 1 < i < N. Fig. 5a-5b show four additional gap sensors 231, 232, 233, 234 that each measure or detect the hood gap hg at an additional position P31, 1 < i < N, in Fig. 5a-5b given as P31, P32, P33, P34.

Fig. 5b discloses another embodiment where the first gap sensor 21 and the second gap sensor 22 are provided at different ends of the hood 11 so that the first gap sensor 21 is at the first end 11A and the second gap sensor 22 is at the second end 1 1B. By providing the first and second sensors 21, 22 at different ends of the hood 11, the hood gap hg across the entire hood 11 is reliably determined to ensure that an adjustment of the hood 11 when the first criterion is not fulfilled renders the hood gap in line with the desired hood gap. Similar to the embodiment of Fig. 5a, additional gap sensors 231 are provided at additional positions P31, 1 < i < N.

In all embodiments of the invention, additional gap sensors 23 may also be provided at positions between the first end 11A and the second end 1113 to detect or measure the hood gap hg at various positions from the first end 1 1A in the first direction D1 to the second end 1 1B.

Fig. 6a discloses the hood gap adjuster 12 in more detail, in an embodiment Where an adjuster 12C is provided in the form of a fork 12C that is coupled to the hood 11 such that movement of the fork 12C results in a corresponcling movement of the hood 11. Suitably, the fork 12C is coupled to the roll 16. The adjuster 12C is linked to an actuator 12D that in this embodiment comprises a hydraulic cylinder operatively connected to the fork l2C by a rod 12G. In other embodiments, the actuator 12D may instead comprise an electric or pneumatic motor or a pneumatic system, and other types of actuators 12D are also possible as long as they are able to move the fork 12C. The hood gap adjuster 12 is operatively connected to the processing circuitry 31 and configured to receive a control signal C from the processing circuitry 31 and to move the hood 11 to adjust the hood gap hg based on this control signal C. This is achieved in the first embodiment by the hood gap adjuster 12 being configured to move the adjuster 12C by extension or retraction of the hydraulic cylinder 12D so that the hood 11 is pushed along the first guide (see Fig. 6b) and the hood gap hg is thereby adjusted. The actuator 12D (see also Fig. 7) is suitably controlled by the control signal C from the processing circuitry 31. The actuator, as stated above, suitably comprises an electrical motor, a pneumatic motor, a hydraulic cylinder or a pneumatic cylinder. Like the hood gap sensors 21, 22, 23, the hood gap adjuster 12 may be operatively connected to the processing circuitry 31 by a Wire or by a Wireless connection. The adjuster 12C may in other embodiments be realised in other Ways than as a fork, as long as the function of pushing on the first roll 16 along the first guide 14 is achieved. The hood gap adjuster 12 also suitably comprises a mechanical 16 stopper 12F that prevents movement of the hood 11 When the actuator 12D is not active, i.e. when no further adjustment is to take place.

Fig. 6b shows the hood gap adjuster 12 with the adjuster 12C coupled to the first roll 16 to move the first roll 16 along the first guide 14. The first guide 14 may be inclined as shown in Fig. 6b, but alternatively the first guide 14 may have a horizontal portion and an inclined portion to allow for adjustment in both the horizontal and the vertical direction, and to allow for opening of the hood for maintenance purposes. Suitably, the roll 16 is configured to be locked in position by the hood gap adjuster 12 when not subjected to an action by the actuator 12D to move the adjuster 12C. This lock is suitably achieved by the mechanical stopper 12F as rnentioned above. Thereby, the hood 11 is prevented from falling down on the dryer cylinder 200 in situations of power loss or other malfunction of the hood adjustment assembly 10.

Fig. 7 discloses the controller 30 of the hood adjustment assembly 10 and also shows the first gap sensor 21, second gap sensor 22 and optional additional gap sensors 23 that are operatively connected to processing circuitry 31 of the controller 30 so that signals S1, S2, S3 indicative of the measured or detected hood gap can be transmitted. Also shown is the gap adjuster 12 to which the processing circuitry is able to transmit the control signal C so that the actuator 12E of the gap adjuster 12 adjusts the position of the hood 1 1. In some ernbodiments, the processing circuitry 31 sends the control signal C to the gap adjuster 12 as such, but in other embodirnents it is connected directly to the actuator 12E.

The processing circuitry 31 is thus configured to receive the first input signal S1 from the first gap sensor 21 and the second input signal S2 from the second gap sensor 22. Suitably, the processing circuitry analyses the detected or measured hood gap from each of the sensors 21, 22 and determines whether the first criterion is fulfilled based on the measured or detected hood gap at the first position P1 and the second position P2. If the first criterion is fulfilled no adjustment is needed and the processing circuitry 31 awaits new signals from the sensors 21, 22. If the first criterion 17 is not fulfilled, however, the processing circuitry 31 determines a desired adjustment of the hood ll that Would bring the hood 1 1 into a position Where the first criterion is fulfilled. The control signal C configured to cause the hood gap adjuster 12 to apply the determined desired adjustment is then generated. This control signal C is transmitted to the hood gap adjuster 12, Which in turn receives the control signal C and moves the hood ll to adjust the hood gap hg based on the control signal C.

In some embodiments, the hood gap adjuster 12 comprises a first end gap adjuster 12A arranged at the first end 1 1A of the hood ll and a second end gap adjuster 12B arranged at the second end 11B of the hood ll. The first and second end gap adjusters 12A, 12B are suitably similar or identical, but in some embodiments they may differ in design or operation as long as they are able to fulfil the function of adjusting the hood 11 in response to the control signal C. ln embodiments With the first and second gap adjusters 12A, 12B, the control signal C is generated as a first end control signal that is configured to cause the first end gap adjuster 12A to apply the determined first end adjustment and a second end control signal that is configured to cause the second end gap adjuster 12B to apply the determined second end adjustment. This Will be explained further below in the method embodiments.

In embodiments comprising at least one additional gap sensor 23, the processing circuitry 31 is also configured to receive an additional input signal from each additional gap sensor, Where said additional input signal is indicative of the measured or detected hood gap at the additional position, and to determine Whether the first criterion for the desired hood gap is fulfilled based also on said measured or detected hood gap at the additional position.

In embodiments comprising the first end gap adjuster 12A and the second end gap adjuster 12B, the processing circuitry 31 is also configured to determine the desired adjustment of the hood as a first end adjustment and a second end adjustment, and to generate the control signal C as a first end control signal Cl that is configured to cause the first end gap adjuster 12A 18 to apply the determined first end adjustment and a second end control signal C2 that is configured to cause the second end gap adjuster l2B to apply the determined second end adjustment.

Fig. 8 discloses operation of the hood adjustment assembly l0, wherein the first gap sensor 21 measures or detects 301 the width of the hood gap hg at the first position P1 of the hood 11 and wherein further the second gap sensor 22 measures or detects 302 the width of the hood gap hg at the second position P2 of the hood ll. The processing circuitry 31 is in turn configured to receive 303 the measured or detected width of the hood gap hg from the sensors 21, 22. The processing circuitry 31 then optionally analyses the measured or detected width of the hood gap hg and may form a combined hood gap based on them. In some embodiments, however, the processing circuitry may be configured to instead determine if the first criterion is fulfilled without first analysing information received from the SCDSOTS.

The processing circuitry 31 determines 305 whether the first criterion is fulfilled based at least one the measured or detected hood gap hg from the sensors 21, 22. If the first criterion is indeed fulfilled, the processing circuitry 31 awaits new signals from the sensors 2 1, 22 that correspond to the width of the hood gap hg being detected or measured again. In some embodiments, the sensors 21, 22 are configured to measure the hood gap hg at predetermined intervals and in other embodiments they may measure the hood gap hg continuously. In yet other embodiments, the processing circuitry 31 may be operatively connected to the sensors 21, 22 in such a way that the measurements at the sensors 21, 22 take place only when requested by the processing circuitry 3 1.

If the first criterion is not fulfilled, the processing circuitry 31 determines 306 a desired adjustment of the hood 11. In embodiments where the hood gap adjuster 12 at either end are not independent from each other, the processing circuitry 31 determines one desired adjustment that is to be performed at both ends of the hood ll simultaneously. In embodiments where the first end gap adjuster 12A can act independently from the second 19 end gap adjuster 12B, the processing circuitry 31 may instead determine the first end adjustment and the second end acljustment for each of the first and second end gap adjusters 12A, l2B. The processing circuitry 31 then generates 307 the control signal C that may comprise the first end control signal Cl and the second end control signal G2. The control signal C is then transmitted from the processing circuitry 31.

The hood gap adjuster 12, or alternatively the first end gap adjuster 12A and the second end gap adjuster 12B, are configured to receive 308 the control signal C from the processing circuitry 31 and to apply 309 the desired adjustment to move the hood 11 based on the control signal C.

A hood adjustment system 100 is formed by two hood adjustment assemblies 10 according to any embodiment of the invention, Where one is a first hood adjustment assembly W at the wet end and the other is a second hood adjustment assembly D at the dry end. Computerized method embodiments Fig. 9 discloses a first embodiment of the Computerized method of the present invention. Step 401 comprises receiving, in processing circuitry 3 1, the first input signal S1 from the first gap sensor 21, and step 402 comprises receiving, in processing circuitry 31, the second input signal S2 from the second gap sensor 22. The first and second input signals are indicative of the measured or detected hood gap at the first position P1 and second position P2 of the dryer hood 11, respectively.

In optional step 403, the processing circuitry 31 may analyze the measured or detected hood gap at the first position P1 and the second position P2.

Step 404 comprises determining, in processing circuitry 31, Whether the first criterion for a desired hood gap is fulfilled based at least on said measured or detected hood gap at the first position P1 and said measured or detected hood gap at the second position P2.

If the first criterion is fulfilled, the method is repeated from step 401.

If the first criterion is not fulfilled, the processing circuitry 31 determines the desired adjustment of the hood in step 405. Step 406 then comprises generating, in processing circuitry 3 l, the control signal C that is configured to cause the hood gap adjuster l2 to apply the determined desired adjustment.

Fig. 10 discloses alternative method embodiments according to various embodiments of the method. It is to be noted that any method step denoted as optional in Fig. 10 may freely be combined With the steps disclosed in Fig. 9 With only minor modifications as apparent to the skilled person. ln embodiments comprising at least one additional sensor 23, the method comprises optional step 407 of receiving, in processing circuitry 3 l, an additional input signal Si, l< i < N (With N denoting a number of additional sensors) from each of at least one additional gap sensor 231, l< i < N, said additional input signal S1, being indicative of the measured or detected hood gap at each additional position P1, l< i < N of the hood ll. ln such embodiments, optional step 403 and steps 404 and 405 are suitably performed based also on the measured or detected hood gap at each additional position P1.

In embodiments comprising the first end gap adjuster 12A and the second gap end adjuster l2B, the method suitably comprises optional step 408 of determining, in processing circuitry Bl, the desired adjustment of the hood ll as a first end adjustment and a second end adjustment, and optional step 409 of generating, in processing circuitry 31, the control signal C as the first end control signal Cl that is configured to cause the first end gap adjuster l2A to apply the determined first end adjustment and the second end control signal C2 that is configured to cause the second end gap adjuster l2B to apply the determined second end adjustment.

Step 404 of determining Whether the first criterion is fulfilled Will now be explained in more detail With reference to the various embodiments of the present invention. 21 When determining whether the first criterion is fulfilled, the processing circuitry 31 may compare each measured or detected hood gap (i.e. at the first position P1, the second position P2, and optionally also additional positions Pi) individually to the first criterion for the desired hood gap. lf at least one of the measured or detected hood gaps does not fulfil the first criterion, it is determined that the first criterion is not fulñlled. Alternatively or additionally, the processing circuitry 31 may analyze the measured or detected hood gaps in optional step 403 and determine at least one combined hood gap based on the measured or detected hood gaps. Such a combined hood gap may be a mean value, a median value, a minimum of the measured or detected hood gaps, a maximum of the measured or detected hood gaps, or may be formed by a combination of these or others. ln some embodiments, the combined hood gap may also comprise measured or detected hood gaps at earlier time instances so that the combined hood gap is a combined hood gap over time. In this way, gradual changes of the measured or detected hood gap may be determined and may be used to determine whether an adjustment of the hood 11 is needed.

The first criterion for the desired hood gap may be defined as whether the measured or detected hood gap at the first and second positions P1, P2, and optionally also at additional positions Pi and/ or a combined hood gap, is above a predetermined minimum hood gap or below a predetermined maximum hood gap or in a predetermined hood gap range. Manufacturing method embodiments The method for manufacturing the hood adjustment assembly 10 comprises providing the hood 11 suitable for mounting in connection with the dryer cylinder 200 to form the hood gap hg between the dryer cylinder 200 and the hood 11, and also comprises providing the first gap sensor 21 configured to measure or detect the width of the hood gap at the first position of the hood 11 and providing the second gap sensor 22 configured to measure or detect the width of the hood gap at the second position of the hood 11. Also, the method comprises providing the hood gap adjuster 12 configured to adjust the hood gap by moving the hood 11 in relation to the dryer cylinder 200, 22 and providing the hood gap controller 30 comprising processing circuitry 31. The processing circuitry 3 1 is configured to perform the steps of the Computerized method according to any of the embodiments herein. Further embodiments In an aspect of the invention there is provided a non-transitory computer- readable storage medium storing instructions Which, When executed by processing circuitry 31 of the hood gap controller 30, cause the hood adjustment assembly to receive, in processing circuitry, a first input signal from a first gap sensor and a second input signal from a second gap sensor, said first and second input signals being indicative of a measured or detected hood gap at a first position and second position of a dryer hood, respectively; determine, in processing circuitry, Whether a first criterion for a desired hood gap is fulfilled based at least on said measured or detected hood gap at the first position and said measured or detected hood gap at the second position; determine, in processing circuitry, a desired adjustment of the hood if the first criterion is not fulfilled; and generate, in processing circuitry, a control signal that is configurecl to cause a hood gap adjuster to apply the determined desired adjustment.

The non-transitory computer-readable storage medium may further store instruction Which, When executed by the processing circuitry 31, cause the hood adjustment assembly to perform the method steps of any of the embodiments described in connection With Figs. 9-10. lt is generally advantageous if the controller 30 is configured to effect the above-described procedure in an automatic manner by executing a computer program 31. Therefore, the controller 30 may include a memory unit, i.e. non-volatile data carrier, storing the computer program 31, which, in turn, contains software for making processing circuitry in the form of at least one processor in the controller 30 execute the actions mentioned in this disclosure When the computer program 31 is run on the at least one processor. In one or more embodiments, the invention may therefore comprise a computer program loadable into a non-volatile data carrier 23 communicatively connected to a processor, the computer program comprising software for executing the method according any of the method embodiments presented in connection With Fig. 9-10 When the computer program is run on the processor. Furthermore, the invention may comprise a non-volatile data Carrier containing the computer program.

It is to be noted that features from the various embodiments described herein may freely be combined, unless it is expiicitly stated that such a combination Would be unsuitable.

Claims (1)

1. Claims Hood adjustment assembly for adjusting a position of a hood on a dryer cylinder, the hood adjustment (10) assembly comprising a hood (1 l) configured to be mounted in connection with a dryer cylinder (200) to form a hood gap (hg) between the dryer cylinder (200) and the hood (11), the hood (1 l) extending in a first direction (Dl) from a first end (1 1A) to a second end (11B), a first gap sensor (21) configured to measure or detect a width of the hood gap (hg) at a first position (Pl) of the hood (l 1), a second gap sensor (22) configured to measure or detect a width of the hood gap (hg) at a second position (P2) of the hood (1 1), a hood gap adjuster (12, 12A, 12B) configured to adjust the hood gap (hg) by moving the hood (1 1) in relation to the dryer cylinder (100), and a hood gap controller (30) comprising processing circuitry (31), wherein the processing circuitry (31) is configured to receive a first input signal (S 1) from the first gap sensor (21) and a second input signal (S2) from the second gap sensor (22), said first and second input signals (S1, S2) being indicative of the measured or detected hood gap (hg) at the first position (P1) and second position (P2), respectively, determine, based at least on said measured or detected hood gap (hg) at the first position (P1) and said measured or detected hood gap (hg) at the second position (P2) whether a first criterion for a desired hood gap is fulfilled, if the first criterion is not fulfilled, determine a desired adjustment of the hood (11), generate a control signal (C) that is configured to cause the hood gap adjuster (12, 12A, 12A) to apply the determined desired adjustment, and Wherein the hood gap adjuster (12, 12A, l2B) is further configured to - receive said control signal (C) from the processing circuitry (31), and - move the hood (11) to adjust the hood gap (hg) based on said control signal (C). . Hood adjustment assembly according to claim 1, Wherein the first position (P1) of the hood (11) is at the first end (1lA) and the second position (P2) of the hood (11) is at the second end (1lB). . Hood adjustment assembly according to claim 1 or 2, Wherein the first position (P1) of the hood (1 1) and the second position (P2) of the hood (1 1) are at the first end (1 1A), and Wherein the first position (P1) and the second position (P2) are separated from each other in a second direction (D2) that is perpendicular to the first direction (D1). . Hood adjustment assembly according to any of claims 1-3, further comprising at least one additional gap sensor (23) configured to measure or detect a width of the hood gap (hg) at an additional position (P3) of the hood (ll), and Wherein the processing circuitry (3 1) is configured to - for each additional gap sensor (23), receive an additional input signal (S3) from the additional gap sensor (23), said additional input signal (S3) being indicative of the measured or detected hood gap (hg) at the additional position (S3), - determine, based also on said measured or detected hood gap (hg) at the additional position (P3) Whether the first criterion for the desired hood gap is fulfilled.5. Hood adjustment assembly according to any previous claim, Wherein the hood gap adjuster (12, 12A, 12B) comprises - A first end gap adjuster (l2A) configured to adjust the hood gap (hg) at the first end (11A) of the hood (11) and - a second end gap adjuster (12B) configured to adjust the hood gap (hg) at the second end (1 1B)of the hood (ll), and Wherein the processing circuitry (31) is configured to - determine the desired adjustment of the hood (11) as a first end adjustment and a second end adjustment, and - generate the control signal (C) as a first end control signal that is configured to cause the first end gap adjuster (l2A) to apply the determined first end adjustment and a second end control signal that is configured to cause the second end gap adjuster (12B) to apply the determined second end adjustment. . Hood adjustment assembly according to any previous claim, Wherein the first gap sensor (21) and the second gap sensor (22), and optionally also the third gap sensor (23), are optical sensors. . Hood adjustment assembly according to any of claims 1-5, further comprising reference markings connected to the hood (1 l), and Wherein the first sensor (21) and second sensor (22), and optionally also the third sensor (23), are configured to measure or detect the width of the hood gap (hg) by detecting the reference markings. . Hood adjustment assembly according to any previous claim, Wherein the hood gap adjuster (12) comprises an inclined guide (14) on Which the hood (ll) rests and also comprises an adjuster (12C) that is configured to move the hood (ll) along the inclined guide (14) in response to the control signal (C). ll. Hood adjustment system comprising a first hood adjustment assembly (10) according to any of claims 1-8 Wherein the hood (11) is a wet-end hood (W) for a dryer cylinder (200) and also comprising a second hood adjustment assembly (10) according to any of claims 1-8 Wherein the hood (1 1) is a dry-end hood (D) for a dryer cylinder. Computerized method for adjusting a position of a hood on a dryer cylinder, the method comprising - receiving, in processing circuitry (31), a first input signal (S1) from a first gap sensor (21) and a second input signal (S2) from a second gap sensor (22), said first and second input signals (S1, S2) being indicative of a measured or detected hood gap (hg) at a first position (P1) and second position (P2) of a dryer hood (200), respectively, - determining, in processing circuitry (31), Whether a first criterion for a desired hood gap is fulfilled based at least on said measured or detected hood gap at the first position (P1) and said measured or detected hood gap at the second position (P2), - determining, in processing circuitry (31), a desired adjustment of the hood (11) if the first criterion is not fulfilled, and - generating, in processing circuitry (31), a control signal (C) that is configured to cause a hood gap adjuster (12) to apply the determined desired adjustment. Method according to claim 10, further comprising - receiving, in processing circuitry (31), an additional input signal (S3) from each of at least one additional gap sensor (23), said additional input signal (S3) being indicative of the measured or detected hood gap (hg) at each additional position (P3) of the hood (11), - determining, in processing circuitry (31), Whether the first criterion for the desired hood gap is fulfilled based also on said measured or detected hood gap (hg) at each additional position (P3).12. Method according to claim 10 or 11, further comprising - determining, in processing circuitry (31), the desired adjustment of the hood (11) as a first end adjustment and a second end adjustment, and - generating, in processing circuitry (31), the control signal (C) as a first end control signal that is configured to cause a first end gap adjuster (12A) to apply the determined first end adjustment and a second end control signal that is configured to cause a second end gap adjuster (12B) to apply the determined second end adjustment. 13. Method according to any of claims 10-12, Wherein the first criterion for the desired hood gap is that the determined hood gap is above a predetermined minimum hood gap. 14. Method according to any of claims 10-12, Wherein the first criterion for the desired hood gap is that the determined hood gap is Within a predetermined hood gap range. 15. Method according to any of claims 10-12, Wherein the first criterion for the desired hood gap is that the determined hood gap is below a predetermined maximum hood gap. 16. A non-transitory computer-readable storage medium storing instructions Which, When executed by processing circuitry (31) of a hood gap controller (30) of a hood adjustment assembly (10) for adjusting a position of a hood (1 1) on a dryer cylinder (200), cause the hood adjustment assembly to: - receive, in processing circuitry (31), a first input signal (S1) from a first gap sensor (21) and a second input signal (S2) from a second gap sensor (22), said first and second input signals (S1, S2) being indicative of a measured or detected hood gap at a first position (P1) and second position (P2) of a dryer hood (11), respectively,- determine, in processing circuitry (31), Whether a first criterion for a desired hood gap is fulfilled based at least on said measured or detected hood gap at the first position (P1) and said measured or detected hood gap at the second position (P2), - determine, in processing circuitry (31), a desired adjustment of the hood (11) if the first criterion is not fulfilled, and - generate, in processing circuitry (31), a control signal (C) that is configured to cause a hood gap adjuster (12) to apply the determined desired adjustment. The non-transitory computer-readable storage medium of claim 16, further storing instruction Which, When executed by the processing circuitry, cause the hood adjustment assembly (10) to perform the method steps of any of the claims 11 to Method for manufacturing a hood adjustment assembly, the method comprising - providing a hood (11) suitable for mounting in connection With a dryer cylinder (200) to form a hood gap (hg) between the dryer cylinder (200) and the hood (11), Wherein the hood (11) extends in a first direction (D1) from a first end (11A) to a second end (1 1B), - providing a first gap sensor (21) configured to measure or detect a width of the hood gap (hg) at a first position (P1) of the hood (11), - providing a second gap sensor (22) configured to measure or detect a width of the hood gap (hg) at a second position (P2) of the hood (11), - providing a hood gap adjuster (12) configured to adjust the hood gap (hg) by moving the hood (11) in relation to the dryer cylinder (200), and - providing a hood gap controller (30) comprising processing circuitry (3 l), Wherein the processing circuitry (31) is configured to - receive a first input signal (S1) from the first gap sensor (21) and a second input signal (S2) from the second gap sensor (22), said first and second input signals (S1, S2) being indicative of the measured or detected hood gap at the first position (Pl) and second position (P2), respectively, - determine, based at least on said measured or detected hood gap at the first position (P1) and said measured or detected hood gap at the second position (P2) Whether a first criterion for a desired hood gap is fulfilled, - if the first criterion is not fulfilled, determine a desired adjustment of the hood (11), - generate a control signal (C) that is configured to cause the hood gap adjuster (12) to apply the determined desired adjustment, and Wherein the hood gap adjuster (12) is further configured to - receive said control signal (C) from the processing circuitry (31), and - move the hood (11) to adjust the hood gap (hg) based on said control signal (C).