CN115161855A

CN115161855A - Adjustable yarn brake

Info

Publication number: CN115161855A
Application number: CN202211017832.5A
Authority: CN
Inventors: 帕·约瑟夫松; T·伯格曼; B·屈韦利埃
Original assignee: Van Der Waals Sweden
Current assignee: Van Der Waals Sweden
Priority date: 2017-08-08
Filing date: 2018-07-03
Publication date: 2022-10-11
Anticipated expiration: 2038-07-03
Also published as: EP3665319B1; WO2019032007A1; EP3665319A1; CN115161855B; CN110997998A; EP3665319A4; CN110997998B

Abstract

The invention describes, inter alia, a method and an apparatus in an adjustable yarn brake. The adjustable yarn brake (10) is configured to have a reference position provided for the adjustable yarn brake. The adjustable yarn brake comprises a position sensor (50), the position sensor (50) being configured to output an output signal indicative of a position of a movable member of the adjustable yarn brake, wherein a braking force of the adjustable yarn brake is set in response to the position of the movable member. The braking force can thus be reset in a cost-effective manner and with low complexity.

Description

Adjustable yarn brake

The application is a divisional application of an application with the application date of 2018, 7 and 3, the application number of 201880050629.3 and the name of the invention of an adjustable yarn brake.

Technical Field

The invention relates to a yarn brake. The invention relates in particular to a yarn brake for use in connection with feeding yarn to a textile machine.

Background

Yarn feeders are used to eliminate yarn tension variations to ensure high quality and to supply the correct amount of yarn to a textile machine (e.g. a shuttleless loom or knitting machine). The spinning quality and the productivity of the textile machine can thereby be increased.

One feature of yarn feeders is to provide a suitable yarn tension to the yarn fed to the textile machine. The applied yarn tension may be provided in different ways. For example, a frustoconical braking member may be used which cooperates with the spool body rim to generate a substantially constant braking force, see EP0534263.

There are various methods of setting and controlling the yarn tension from a yarn feeder:

the yarn braking part cooperating in a flexible manner with the spool body of the yarn feeder may be adapted to provide a braking force acting on the yarn drawn from the spool body when forced against the spool body.

It is also possible to place the yarn brake after the yarn feeder, at some point on the path from the yarn storage to the textile machine. The yarn brake may be of the nip type or of the yarn deflection type. Typical clip-type brakes are the leaf brake (leaf brake) and the disc brake (disc brake). A yarn brake of the clip type is described in EP 2354070.

Furthermore, the yarn tension can be set in different ways:

mechanically setting the yarn brake in a position to obtain the desired braking force by means of a knob or similar device.

-a motor or actuator to set the yarn brake to a position where a desired braking force is obtained. For example, US 6539982 describes a closed loop system in which a motor is controlled to sense the position of a brake component and control the brake component to a desired position when the brake position deviates from the desired brake component position.

There are also systems that adjust or vary the yarn tension during weft insertion to achieve different yarn tensions in different parts or areas of the weft insertion cycle. Examples of such systems with varying yarn tension are described by way of example in EP 1743967 and US 5343899. Such systems are advanced but also difficult to use. For example, it may be difficult to find the correct settings for each region. Moreover, such systems are also typically complex and expensive.

More advanced systems comprise a combination of in-zone controlled tensioners (yarn brakes) and yarn tension sensors. Such systems are of course also complex and expensive and may be required to be used. An example of such a system is described in EP 1646573.

It is always desirable to provide improved yarn feeds. Therefore, there is a need for an apparatus that improves or facilitates the feeding of yarn to a textile machine.

Disclosure of Invention

It is an object of the present invention to provide an improved yarn feed and in particular an improved yarn brake which can facilitate the feeding of yarn in a correct manner and with less complexity.

This and/or other objects are achieved by the yarn brake and the related device proposed by the present invention.

As has been recognized, the weaving mill needs to repeat the setup when setting up the article again (e.g., knitting or tatting), and also to transfer the setup from one textile machine to another. In today's manual systems this is not possible, because the braking force or the mechanical setting/pretension/position of the yarn brake for controlling the yarn tension cannot be read.

Today, the only way to do the setup is to pull the yarn in hand and try to feel if the setup is correct, or to use a spring gauge to pull and measure the static yarn tension by hand, and then make adjustments and try again until the proper level is found. Both methods require time and require trial and error elements.

Furthermore, yarn tension sensors are good but expensive and add complexity. According to the present invention, a much simpler and cheaper system is provided which can provide many benefits from more advanced and expensive systems, but at low cost and complexity. It is therefore an object of the invention to enable a repeatable and transferable setting of the set braking force with low complexity.

This can be achieved by a yarn brake configured with a defined reference position. The reference position can be defined as generally the zero position, in which the yarn brake is just starting to act on the yarn. This is to say, for example, when the two braking surfaces are just in contact with each other during crimping, or when the braking member is just in contact with the rim of the spool body without applying any braking force to the yarn. This zero position may be determined manually or automatically by a sensor, as described in co-pending patent application No. pct/SE 2017/050045. The yarn brake comprises a position sensor for detecting the position of a movable member of the yarn brake, such as a brake component or a brake component holder, relative to a defined zero position. Outputting the detected position to provide a value indicative of the tension of the yarn.

The output position provided by the position sensor may be used in different ways. I.e. the output position is output from the device for use outside the adjustable yarn brake. The position sensor output may be presented to the operator, for example on a display on the yarn brake or feeder, or the position sensor output may be transmitted to the textile machine and presented on a textile machine display or in a control system for the textile machine. The position sensor output may also be transmitted to a portable unit (e.g., a smartphone) and displayed there. In addition, the output of the position sensor may be stored in memory for later use. In particular, the position sensor output as well as other information about the current settings of the textile machine and/or yarn feeder can be stored. For example, yarn type/material, yarn quantity, machine speed and width, and brake characteristics may be stored for future use. The brake characteristic may be, for example, how much braking force the yarn brake applies to a given yarn at each given pre-tension setting. Such position sensor outputs may be stored locally on the yarn brake or textile machine, or may be transmitted to a central location (e.g. a central controller or server connected to a number of yarn brakes).

If the same yarn brake and the same yarn are used in another setting, the setting can be transferred from one feeder to another or from one textile machine to another. It is also possible to store the settings and repeat the settings when the same item is used later.

Knowing the width and speed of the textile machine, the braking characteristics and the yarn, a setup table can be created in which the setup for a new article that has not been run before can be found. If the setting of the brake is displayed, the appropriate setting can be found directly for the new item. A look-up table or computer program/application may be used with a given loom width and speed, yarn and brake type, and recommended yarn brake settings to find the recommended pre-tension. The yarn brake is then adjusted until the recommended pretension is reached. The current yarn tension can also be displayed on the display. It can be fine-tuned, if not perfectly set, and then stored as a default setting the next time the product is manufactured, which is a good start.

According to one embodiment, an adjustable yarn brake is provided. The adjustable yarn brake is configured with a set reference position. The adjustable yarn brake comprises a position sensor configured to output a signal indicative of a position of a movable member of the adjustable yarn brake relative to a reference position, wherein a braking force of the adjustable yarn brake is determined by the position of the movable member. The adjustable yarn brake is configured to output a signal from the position sensor to a display or to store an output signal from the position sensor in a memory. The display may be a local display provided on the adjustable yarn brake or located elsewhere, for example on the textile machine or on a controller interface. The display may also be a display on a handheld unit such as a smart phone or the like. Likewise, the memory can be a local memory in the adjustable yarn brake, or also a memory located elsewhere (for example on the textile machine or in the controller or some server) which is configured to receive and store position sensor output data from the adjustable yarn brake and other such adjustable yarn brakes. Thereby, the position of the yarn brake can be determined and can easily be re-used at a later point in time or in another setting to regenerate the same yarn tension.

According to one embodiment, the yarn brake comprises a display connected to the position sensor. Thus, braking force may be displayed directly to an operator in a cost-effective manner without the need for complex computer systems or other complex components. Alternatively or additionally, the output from the position sensor is configured to be operably connected to a display at another location, for example a display on a textile machine or a handheld unit such as a smartphone.

The yarn brakes may be of different types. According to some embodiments, the adjustable yarn brake is configured to have a manually set reference position. The yarn brake may then comprise an input device for receiving a manual input signal representing an operator-determined reference position in which the braking force of the adjustable yarn brake is just starting to act. In some embodiments, the adjustable yarn brake is configured to automatically set the reference position. The adjustable yarn brake is then configured to set a reference position of the adjustable yarn brake in response to an output signal of a movement/position sensor adapted to automatically detect when said reference position is reached.

The position sensor may be an absolute sensor. Thus, the sensor may be disconnected and still provide the correct output when reconnected. For example, the sensor may advantageously comprise a rotatable permanent magnet. A sensor including a rotatable permanent magnet may be configured to rotate less than one full revolution throughout the range of settings of the sensor.

The invention also extends to a method for controlling a yarn feeder according to the above.

Drawings

The invention will now be described in more detail, by way of non-limiting example, with reference to the accompanying drawings, in which:

figure 1 is a view showing a yarn feeder,

figure 2 is a view showing a detail of the yarn feeder,

figure 3 is a view showing a system for controlling the yarn tension of a plurality of yarn feeders,

figure 4 is a flow chart illustrating the steps performed when controlling the yarn tension,

figure 5 is a view of another braking mode,

figure 6 shows a yarn feeder with an electronic yarn tension actuator,

figure 7 shows an alternative embodiment of a yarn feeder with an electronic yarn tension actuator,

figure 8 is a view of the first yarn feeder including a position sensor,

figure 9 is a view of a second yarn feeder including a position sensor,

fig. 10 a-10 c depict a yarn feeder device with an independently adjustable yarn brake,

FIGS. 11a and 11b illustrate the implementation of a position sensor, an

Fig. 12 is a flow chart showing the steps performed when determining the position of the adjustable yarn brake.

Figures 13 a-13 c show an adjustable yarn brake according to another embodiment.

Detailed Description

Hereinafter, a yarn brake and a yarn feeding device for a textile machine will be described. In the drawings, like reference characters designate like or corresponding parts throughout the several views. It will be understood that these drawings are for illustration only and do not limit the scope of the invention in any way. Furthermore, features from the different described embodiments may be combined to meet specific implementation requirements or to achieve a desired yarn feeding device. For example, a separate yarn brake can be provided without a yarn feeder upstream of the yarn brake.

The invention aims to achieve a repeatable and transferable arrangement of the yarn braking force for the yarn brake. The yarn brake is configured to have a defined reference position serving as a zero position. The zero position can be set manually and also automatically as described in co-pending patent application No. pct/SE 2017/050045. The following description with reference to fig. 1-7 describes an example of such automatic setting of the zero position described in PCT/SE 2017/050045.

In fig. 1a yarn feeder 10 is depicted. In the yarn feeder 10 of fig. 1, an extension arm 12 (commonly referred to as a cap in the yarn feeder art) is arranged to extend from a housing 14, for example as described in U.S. Pat. No. 5,947,403. The yarn feeder 10 comprises an adjustable brake comprising a yarn brake assembly 16, the yarn brake assembly 16 being shown in fig. 1 in its braking position. The yarn braking section 16 may be, for example, a frustoconical section 16, but may be of other types or shapes. The brake component may be made of a plastics material such as PEEK or PET. The braking member 16 may be arranged in a flexible manner. The flexible manner in which the braking member engages the spool body may be achieved in different ways. Flexibility may be achieved by having the braking member 16 suspended by a spring, and/or the braking member may be at least partially made of a flexible/resilient material that deforms or may otherwise provide flexibility when the braking member is pressed towards the spool body. Thus, the flexible action of the detent member in cooperation with the spool body may be of any conventional type and will not be discussed in detail herein. The yarn braking component 16 engages the withdrawal edge of the spool body 18 in a conventional manner. Thus, the yarn braking component 16 can be moved back and forth along the axis a to control the braking force applied to the yarn being drawn from the yarn feeder 10. In one embodiment, the yarn brake component 16 may be connected to the extension arm 12 via a brake component holder 27 provided on the extension arm 12 that is slidable along axis a.

In fig. 1, the yarn braking member 16 is in a braking position in which the yarn braking member 16 is pressed axially against the spool body 18 with a predetermined, settable axial force. This position can be varied by operating the motor of the brake motor assembly 20 to vary the contact pressure of the yarn braking member 16 by moving the braking member holder 27 along the axis a in a manner known per se.

In order to achieve an electrically controlled setting of the braking force without the use of downstream yarn tension sensors, it is necessary to establish a reference position in which the position of the braking component corresponds to the known braking force. According to one embodiment, a position is established where the braking force just starts to act. In such a position there will be a braking force, but the magnitude of the braking force is very small and does not have any significant effect on the yarn tension. Such a position may be referred to as the 0 position (zero position) or the initial braking position of the brake member. In other words, this is the position where the braking member has just come into contact with the spool body. This position may be saved in memory to establish a reference position that may be used when electronically controlling the braking force. The memory can be located in the yarn feeder or elsewhere (e.g. in a control system arranged separately or integrated in the textile machine).

Various methods may be used to determine this initial braking position. According to a first embodiment, the initial braking position can be determined manually. For example, a thin instrument (not shown) such as a conventional gauge in the form of a metal or plastic sheet, typically about 0.1mm or less in thickness, may be placed in the gap between the brake member 16 and the spool body 18. The brake member 16 is then driven towards the spool body 18 by, for example, manipulating the button 5, and when the brake member squeezes the instrument between the brake member and the spool body so that it cannot be removed without applying additional force, the initial braking position is set by manually commanding the memory by manipulating the 0 setting button 6. The initial detent position may also be set by simply visually observing the detent member 16 when the detent member 16 accurately reaches the spool body 18 and setting the initial detent position in memory accordingly. There may also be a button 7 for moving the brake holder 27 in a direction away from the spool body. In another embodiment, the

push buttons

5, 6 and 7 can be located on a Human Machine Interface (HMI) on the central control unit, for example in the Machine terminal of the textile Machine.

In the second embodiment, a sensor is provided to detect movement of the brake member 16 when the motor 20 is operated to move the brake member towards the spool body. When the braking member 16 is no longer moving but the motor 20 is still running, this indicates that the braking member has struck the spool body, and the initial braking position may be set to the position when the sensor first detects no movement while the motor is still running. The sensor may be any type of sensor that detects movement. The sensor may be of the optical type, for example, to sense the distance between the movable brake member holder and the cone. The sensor may also be of the magnet-hall sensor type, but may also be an inductive sensor. A dust insensitive sensor is generally advantageous.

In fig. 2, a detail of the yarn feeder 10 of fig. 1 is shown, showing a possible arrangement of such a movement sensor. In fig. 2, a hall sensor 25 is used together with a permanent magnet 24. The hall 25 sensor is located at the moving brake member holder 19 and the magnet 24 is attached to the brake member 16. Alternatively, the hall sensor may be located in a fixed position on the yarn feeder 10 and the permanent magnet 24 is connected to the movable brake part 16.

In the third embodiment, the motor torque of the motor 20 for moving the brake member 16 is monitored. As the motor torque increases, this indicates that the braking member 16 has reached the spool body 18 precisely and begins to stretch certain elastic members of the braking member (e.g., the spring 26 shown in fig. 2). The position where the motor torque starts to increase is set in the memory as the initial braking position.

In the fourth embodiment, when the initial braking position is determined, a sensor that detects deformation of the elastic portion of the braking member 16 may be used. In such embodiments, a sensor is provided to sense when a portion of the brake member begins to deform and to take that moment as the initial braking position has been precisely reached. For example, if the braking member 16 is provided with a spring 26, which spring 26 is stretched when the braking member strikes the spool body, a sensor sensing that the spring 26 is stretched may be used to set the initial braking position.

In fig. 5, another embodiment of a hall sensor-a permanent magnet type solution-is shown. In the embodiment according to fig. 5, another type of braking member is used. The braking member 30 is of the type known for example from EP0963335 and is made of an elastomer, for example polyurethane. The hall sensor 32 is located at a fixed position of the yarn feeder 10 and the permanent magnet 31 is attached to the brake part 30.

In fig. 6, another embodiment is shown. According to the embodiment shown in fig. 6, an actuator 35, such as an electromagnet or an electric motor, is used to apply a braking force to the brake holder 38, which in turn transmits the force to the brake component 16 via the spring 26. The actuator 35 may be position controlled and have a movement/position sensor (e.g. a hall sensor 36 co-acting with a permanent magnet 37). When the actuator starts to move to apply a force, both the hall sensor 36 and the hall sensor 25 detect the movement. When the braking member 16 is in contact with the spool body 16, the hall sensor 25 detects that the permanent magnet 24 is no longer moving, while the hall sensor 36 of the actuator 35 still detects movement, and then serves as an indication of the 0 position of the braking member being reached.

Fig. 7 shows another embodiment. In the embodiment of fig. 7, an actuator 35 (e.g., an electromagnet or electric motor) is used to apply a braking force to the brake holder 38, which in turn transmits the force to the brake component 16 via the spring. The actuator may be position controlled and have movement/position sensors (e.g., hall sensor 36 and permanent magnet 37). When the actuator begins to move to apply a force, the hall sensor 36 detects the movement. When the braking member 16 comes into contact with the spool body 18, the current for driving the actuator 35 will increase. Sensors, such as those in the drive circuit, are used to monitor the drive current and correlate the actual current to the actual position of the actuator as detected by the hall sensor 36 and the permanent magnet 37. When the drive current starts to increase, this will be used as an indication that the brake member reaches the 0 position.

When a reference position, such as an initial braking position (0 position of the braking member), is determined, a required braking force is set based on the reference position. According to one embodiment, the desired braking force is set as a percentage of the maximum force applicable. According to another embodiment, the desired braking force may be set relative to the range of movement when the motor or actuator drives the braking component toward (or away from) the spool body.

For example, if the motor is a stepper motor, the number of steps relative to a reference position may be used to control the braking force. According to another example, when the motor is a DC motor, encoders or other sensors may be used to detect rotation of the motor and axial movement of the brake member holder 27, respectively, to determine the braking force, and hence the yarn tension. The sensors may be of the absolute or relative type. This may be required and provide a home position if it is a relative type of sensor.

An alternative to an encoder could be used, which has a rotating magnet and two hall sensors with a relative position between them, for example a mutual distance of 90 degrees. This will form two sinusoidal signals 90 degrees apart, providing a good angle sensor. For this system, typically a maximum of 10-15 positions can be extracted per revolution, with high resolution. Another type of sensor that can be used in a similar way to produce the corresponding function is a so-called rotary magnetic sensor chip.

Knowing the parameters of the specific case, it is possible to set the required yarn tension according to the found and stored initial position value (0 position of the braking member) without using a downstream yarn tension sensor. This can be done, for example, using a look-up table with desired values (settings) for various combinations of yarn tension/yarn/loom type, width and speed/brake component/yarn feeder type (or any desired subset of such parameters). By placing the look-up table in the central control system, a plurality of yarn feeders can be remotely controlled from one single location.

In fig. 3, a control system 1 for controlling the yarn tension of a plurality of yarn feeders 10 is shown. The control system comprises a central controller 2 connected to each yarn feeder 10 of the system. The controller 2 may include: a memory 3 storing the lookup table as described above; and a control unit 4 adapted to control the braking force of the yarn feeder 10 connected to the control unit 4 by wire or wirelessly. Thereby, the yarn tensions of the plurality of yarn feeders can be set remotely from a single central location. For example, if a particular setting of yarn tension can be made good for weaving performance, the setting can be saved in a look-up table and used again for other yarn feeders running the same "weaving application". Thus, in some embodiments, the system is adapted to apply a self-learning algorithm that saves useful settings for a machine and enables the settings to be reused on the same machine or machines having the same configuration. In one embodiment, the controller and/or memory may be located in the loom or knitting machine, and a loom terminal (HMI) may be used to monitor and input settings.

The arrangement according to fig. 3 can be used to achieve a transferable and repeatable arrangement. According to an exemplary operating mode, the operator sets the yarn tension by manually turning a setting button or some other means for setting the braking force. The position is sensed by a position sensor and the position sensor value is output to reflect the set yarn tension. The position is displayed on the built-in display and may also be read to the loom or a remote unit (e.g. a cell phone). Thus, good working settings can be transferred to other weaving machines and also be stored manually or automatically in a setting table and used as a starting value when the same or similar items are woven next time. If several lanes or machines have the same yarn, the setup can be repeated and the yarn delivered to the other yarn feeders.

In order to further facilitate a fast and accurate setting of the adjustable yarn brakes, a centralized control center system may be used to collect and compare information from different adjustable yarn brakes. This will enable the central system to identify problems and promote a good working environment. For example, a control center such as the controller 2 described above may be configured to identify loom stop types, locations, times to re-run, interventions to correct problems, weave patterns, occurring down times, tunnels, bobbins, etc. When doing so, the sensor position data from the adjustable yarn brake can be used to identify the latest setting change in the braking force or other braking force setting, which change would lead to a reduction in the productivity of the particular textile machine.

For example, by analyzing the data of the position sensor of the adjustable yarn brake, it is possible to determine when the yarn tension knob is adjusted, the frequency of the adjustment and the number of adjustments. Furthermore, the data may be analyzed to determine how the setting of the braking force is associated with machine stops (frequency and type of stop) and with which shuttle peg or full/empty shuttle peg.

In order to make such a diagnosis more effective, the adjustable yarn brake can be configured to send a signal from the position sensor to another position at predetermined time intervals or upon the occurrence of certain predetermined events. An example of such an event may be changing a setting or the number of times a setting is changed. The time to detect and report such an event can also be recorded by means of an adjustable yarn brake and transmitted to the control center. In fig. 4, a flow chart is shown illustrating some of the procedural steps that may be performed in controlling the yarn tension according to the above teachings. First, in step 401, the braking member is driven toward the spool body in a state where there is no braking force. Next, in step 403, a position is determined where the braking member just reaches the spool body and is thus in contact with the spool body. In step 405, the position determined in step 403 is saved as a reference position. Then, in step 407, the braking force is controlled by measuring how the electric drive motor or brake drives the braking component relative to said reference position, thereby controlling the yarn tension.

In order to ensure a reproducible setting of the yarn tension used in a particular setting in a cost-effective manner, a position sensor may be used and configured to output an output signal indicative of the position of a movable member of the adjustable yarn brake. This position can then be displayed and/or stored and reused later to achieve similar or identical settings at a later point in time or on another textile machine. According to some embodiments, the display is provided on the yarn brake, or in some embodiments on the yarn feeder where the yarn brake is located. By providing a display in proximity to the position sensor, in some embodiments, the sensor may be wired to the display and need not be connected to a wireless interface of the position sensor. Thus, the design can be made simpler and more compact. In addition, the costs can be kept low. However, it is also envisaged that the display may be located at another location, for example on a textile machine or on a portable device (e.g. a smart phone or similar device).

Various embodiments incorporating a position sensor will now be described in connection with fig. 8-13.

In fig. 8, a view of a yarn feeder 10 similar to fig. 1 is shown, the yarn feeder 10 comprising a position sensor 50, the position sensor 50 detecting the position of a movable member of the adjustable yarn brake, e.g. a brake component or a brake component holder, with respect to a defined zero position. The position sensor 50 is typically located inside the yarn feeder 10 and is described in more detail below. Outputting the detected position to provide the tension of the yarn. The output signal from the position sensor may be displayed on a display 52 provided on the yarn feeder 10. The setting buttons 5 and 7 are as described above in connection with fig. 1. In addition, a reset button 6 is provided as described above in connection with fig. 1.

In fig. 9, a view of a further yarn feeder is shown with a manual arrangement of the yarn brake and comprising a position sensor 50 to detect the position of a movable member of the adjustable yarn brake, e.g. the brake section or the brake section holder, with respect to a defined zero position. Also, the position sensor 50 is generally located inside the yarn feeder 10, which will be described in detail below. In contrast to the yarn feeder of fig. 8, the yarn feeder 10 of fig. 9 comprises a manual knob 58 for setting the yarn tension/position of the brake assembly holder. The output signal from the position sensor may be displayed on a display 52 provided at the yarn feeder 10. The zero or reference position may be reset using button 56.

In fig. 10 a-10 c, another yarn feeder device is shown. In fig. 10a the yarn feeder 10 is similar to the type shown in fig. 9, and a separate adjustable yarn brake 60 is added downstream of the yarn feeder 10. Although fig. 10a shows a manually adjustable yarn feeder, it is also conceivable that the yarn feeder may be an electrically adjustable yarn feeder as shown in fig. 1.

In fig. 10b, a manually adjustable independent yarn brake 60 is shown. The yarn brake 60 of fig. 10b comprises a position sensor 50 to detect the position of a movable member 68 (e.g. a brake component or a brake component holder or here a brake pad) of the adjustable yarn brake 60 relative to a defined zero position. The position sensor 50 is typically located inside the yarn brake 60 and is described in more detail below. The yarn brake 60 in fig. 10b comprises a manual knob 66 to set the yarn tension/position of the yarn brake member 68. The output signal from the position sensor 50 can be displayed on a display 62 arranged on the yarn brake 60. The zero or reference position may be reset using the button 64.

In fig. 10c, an electrically adjustable, independent yarn brake 60 is shown. The yarn brake 60 of fig. 10c comprises a position sensor 50 to detect the position of the movable member 78 (e.g. a brake part or a brake part holder or here a brake pad) of the yarn brake 60 relative to a defined zero position. The position sensor 50 is typically located inside the yarn brake 60, as described in more detail below. The yarn brake 60 in fig. 10c comprises

adjustment buttons

75, 77 to set the yarn tension/position of the yarn brake. The output signal from the position sensor 50 can be displayed on a display 72 arranged on the yarn brake 60. The zero position or reference position may be reset using the button 76.

The sensor for detecting the actual position of some moving member of the yarn brake, e.g. the brake part or the brake holder, may be any type of known position sensor.

However, the position sensor is preferably of the absolute type. That is, the sensor should preferably detect the correct position relative to a zero position or a reference position even if the position changes during power-off. Relative sensors (e.g. simple encoders) cannot meet this requirement. In addition, the range of the yarn brake is usually relatively long, typically 15mm. This setting is usually made with a knob attached to the screw. If a rotary encoder is placed on the screw, it will not be able to be used as an absolute sensor because if it is set at power off, it cannot be determined by the current rotation of the encoder wheel alone. Therefore, a sensor that detects an absolute position is generally required.

In order to provide an absolute sensor, a toothed rack can be connected or built up, for example, on the brake support or on the brake part. The rack drives a cogwheel with a rotating magnet at the end of the cogwheel. The position signal is then generated using an absolute encoder or a contactless magnetic angle sensor, for example of the magnetoresistive type. It may be advantageous to gear so that the absolute encoder or magnet rotates less than one revolution throughout the range of settings and the absolute position can be read even if the position changes during power down.

In fig. 11a and 11b, an exemplary embodiment of a position sensor 50 is shown as being implemented in a yarn feeder 10. Of course, the sensor 50 can be arranged equally well in a separate yarn brake in a similar manner. Fig. 11a is a cross-sectional view from the side of the yarn feeder 10 comprising a yarn braking section 86. The yarn braking part 86 is here conical, as shown in fig. 1. Fig. 11b is a perspective view of the view in fig. 11 a. In fig. 11a and 11b, the rack 85 is connected to the brake support 81. The rack 85 drives a cogwheel 84, which cogwheel 84 has a rotating magnet 83 at its end. Then, a position signal is created using an absolute encoder or a contactless magnetic angle sensor, for example of the magnetoresistive type. Here a magnetic angle sensor 82 is used. When the brake support is adjusted to adjust the braking force, the arrangement in fig. 11a and 11b will cause the magnet to rotate and the sensor will output a new position corresponding to the now set braking force. A gear may be provided so that the magnet 83 rotates less than one revolution throughout the range in which the sensor is disposed, and the absolute position can be read even if the position changes during power-off. In response to adjustment of the brake, the magnet will rotate and the output of the sensor 50 will result in a new angular position that can be converted to a new position of the brake retainer and then used (e.g., displayed or stored) in any desired manner.

In fig. 13 a-13 c, a further exemplary embodiment of an adjustable yarn brake 10 is shown. The embodiment according to fig. 13 a-13 c is similar to the embodiment shown in fig. 9. In the embodiment of fig. 13 a-13 c, the position sensor 50 is located outside the body of the adjustable brake 10, as opposed to the embodiment of fig. 9. As shown in fig. 13b, the position sensor may be a magnetic sensor 82. Further, a worm 85a for rotating the cog wheel 84 is provided, the cog wheel 84 holding a magnet 83, the magnet 83 providing a rotating magnetic field detected by the magnet sensor 82. The worm 85a corresponds to the rack 85 used in the embodiment described in fig. 9, and performs the same function.

In fig. 12, a flow chart illustrating the steps performed when determining the position of the adjustable brake is shown. First, in step 901, a reference position of an adjustable yarn brake is determined. The reference position may generally be, as described above, when the braking force has just started to act on the yarn. Next, in step 903, a signal from the position sensor is output. The output signal from the position sensor is indicative of the position of the movable member of the adjustable yarn brake relative to a reference position. In other words, the output signal from the position sensor will give a value indicating how much the movable member of the adjustable brake has moved from the reference position. Then, in step 905, the output signal from the position sensor is displayed or stored in a memory. The value of the output signal may then be reused at another time or in another setting to recreate the same setting in step 907. Thus, a position sensor is used which can give the position of the movable member of the adjustable yarn brake, wherein the position of the movable member gives the braking force of the adjustable yarn brake, which can be remembered and reused. Thereby, a system of low complexity can be formed that is cost effective.

Claims

1. An adjustable yarn brake (10, 60) configured to have a reference position provided for the adjustable yarn brake, characterized in that:

-a position sensor (50) is configured to output an output signal indicative of a position of a movable member (68, 78, 81) of the adjustable yarn brake relative to the reference position, wherein a braking force of the adjustable yarn brake is determined by the position of the movable member (68, 78, 81), wherein the adjustable yarn brake (10, 60) is configured to output a signal from the position sensor to a display or to store the output signal from the position sensor in a memory.

2. The adjustable yarn brake of claim 1, comprising: a display (52, 62, 72) connected to the position sensor (50).

3. The adjustable yarn brake of claim 1 or 2 wherein the output from the position sensor is configured to be operably connected to a display of another position.

4. The adjustable yarn brake of claim 3 wherein the output from said sensor is configured to be operatively connected to a display on a textile machine or hand held unit.

5. The adjustable yarn brake of any one of claims 1-4, wherein the adjustable yarn brake is configured to send an output signal from the position sensor to be stored in a memory of another position.

6. The adjustable yarn brake of any one of claims 1-5, wherein the adjustable yarn brake is configured to send a signal from the position sensor to another position at predetermined time intervals.

7. The adjustable yarn brake of any one of claims 1-6, wherein said adjustable yarn brake is configured to send a signal from said position sensor to another position in response to a predetermined event.

8. The adjustable yarn brake of any one of claims 1 to 7, wherein the adjustable yarn brake is configured to manually set the reference position.

9. The adjustable yarn brake of claim 6, further comprising: an input device for receiving a manual input signal representing the operator-determined reference position in which the braking force of the adjustable yarn brake is just starting to be active.

10. The adjustable yarn brake of any one of claims 1-7, wherein the adjustable yarn brake is configured to automatically set the reference position.

11. The adjustable yarn brake of claim 10, wherein the adjustable brake is configured to set a reference position of the adjustable brake in response to an output signal of a movement/position sensor adapted to automatically detect when the reference position is reached.

12. Adjustable yarn brake according to one of the claims 1 to 11, wherein the position sensor (50) is an absolute sensor.

13. Adjustable yarn brake according to claim 12, wherein the position sensor (50) comprises a rotatable permanent magnet (83).

14. Adjustable yarn brake according to claim 13, wherein the position sensor (50) comprises a rotatable permanent magnet configured to rotate less than one full turn over the entire setting range of the sensor.

15. Yarn feeder (10) comprising an adjustable yarn brake according to any of claims 1-14.

16. Yarn feeder as in claim 13, comprising: a display (52) connected to the position sensor.

17. A method for facilitating setting of a braking force of a yarn brake, which yarn brake comprises a position sensor configured to output an output signal indicative of a position of a movable member of an adjustable yarn brake relative to a reference position, wherein the braking force of the adjustable yarn brake is determined by the position of the movable member,

- (901) determining a reference position of the adjustable yarn brake,

- (903) outputting a signal from the position sensor, an

- (905) displaying or storing a value representative of said output signal.