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Title:
DRIVING DEVICE FOR A WEAVING MACHINE WITH ASSISTING DEVICE
Document Type and Number:
WIPO Patent Application WO/2019/201433
Kind Code:
A1
Abstract:
Driving device comprising a drive shaft (5) with a drive axis (7), at least one actuator (31) exerting a drive torque on the drive shaft (5), wherein a required drive torque varies with an angular position of the drive shaft (5), and an assisting device (33) with a first magnet arrangement (35) and a second magnet arrangement (37), wherein the first magnet arrangement (35) and the second magnet arrangement (37) are displaced relative to one another with the rotation of the drive shaft (5), wherein the drive torque of the at least one actuator (31) and the assisting drive torque of the assisting device (33) provide a resulting drive torque on the drive shaft (5), wherein the assisting device (33) is a passive assisting device, and wherein the first magnet arrangement (35) comprises at least one first permanent magnet (135,136) and the second magnet arrangement (37) comprises at least one second permanent magnet (137,138). Assembly group of a weaving machine comprising such a driving device, weaving machine comprising such a driving device and method for driving a drive shaft (5) in a weaving machine comprising such a driving device.

Inventors:
ROELSTRAETE KRISTOF (BE)
DELBOO EMMANUEL (BE)
COEMELCK DIMITRI (BE)
Application Number:
PCT/EP2018/059815
Publication Date:
October 24, 2019
Filing Date:
April 18, 2018
Export Citation:
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Assignee:
PICANOL (BE)
International Classes:
D03C1/00; D03C1/14; D03D47/27; D03D49/60; D03D51/02
Domestic Patent References:
WO2005010257A12005-02-03
WO2004035891A22004-04-29
WO2005010257A12005-02-03
WO2017032556A12017-03-02
Foreign References:
JPH04681U1992-01-07
JP2004052150A2004-02-19
EP0726345A11996-08-14
DE10346227A12005-04-14
Attorney, Agent or Firm:
PATENTANWÄLTE RUFF, WILHELM, BEIER, DAUSTER & PARTNER MBB (DE)
Download PDF:
Claims:
CLAIMS

1. Driving device comprising a drive shaft (5) with a drive axis (7), at least one actuator (31 ) exerting a drive torque on the drive shaft (5) to rotate the drive shaft (5) about the drive axis (7), wherein a required drive torque varies with an angular position of the drive shaft (5), and an assisting device (33) with a first magnet arrangement (35) and a second magnet arrangement (37), wherein the first magnet arrangement (35) and the second magnet arrangement (37) are displaced relative to one another with the rotation of the drive shaft (5), and wherein in at least one angular position of the drive shaft (5) an attractive and/or repulsive force between the first magnet arrangement (35) and the second magnet arrangement (37) exerts an assisting drive torque on the drive shaft (5), wherein the drive torque of the at least one actuator (31 ) and the assisting drive torque of the assisting device (33) provide a resulting drive torque on the drive shaft (5), characterized in that the assisting device (33) is a passive assisting device, wherein the first magnet arrangement (35) comprises at least one first permanent magnet (135, 136) and the second magnet arrangement (37) comprises at least one second permanent magnet (137, 138).

2. Driving device according to claim 1 , characterized in that the first magnet arrangement (35) comprises at least one first magnetic pole and the second magnet arrangement (37) comprises at least one second magnetic pole, which is of opposite polarity to the at least one first magnetic pole, wherein within a movement range of the drive shaft (5), the first magnet arrangement (35) and the second magnet arrangement (37) are displaced relative to one another to form at least one stable magnetic equilibrium point, wherein by means of the at least one actuator the first magnet arrangement (35) and the second magnet arrangement (37) are moved relative to each other out of the at least one stable magnetic equilibrium point.

3. Driving device according to claim 1 or 2, characterized in that a magnetic flux field is generated between the first magnet arrangement (35) and the second magnet arrangement (37), wherein the first magnet arrangement (35) and the second magnet arrangement (37) are displaced relative to one another in a direction transverse to the magnetic flux field generated.

4. Driving device according to claim 1 , 2 or 3, characterized in that the drive shaft (5) is drivingly connectable to at least one driven component (3) to move at least one driven component (3) to-and-fro along a movement path and/or to rotate at least one driven component (3) about an axis along a circumferential movement path upon rotation of the drive shaft (5), wherein in particular the drive shaft (5) is drivingly connectable to the at least one driven component (3) via at least one transmission element (9, 11 , 13, 17, 19, 21 ).

5. Driving device according to claim 4, characterized in that upon its movement, the at least one driven component (3, 48, 69) and/or the at least one transmission element (9, 11 , 13, 17, 19, 21 ) exert or exerts a reaction torque on the drive shaft (5), wherein the first magnet arrangement (35) and the second magnet arrangement (37) are arranged such that at least in one angular position of the drive shaft (5) the assisting drive torque exerted by the first magnet arrangement (35) and the second magnet arrangement (37) is counteractive to the reaction torque.

6. Driving device according to any one of claims 1 to 5, characterized in that the first magnet arrangement (35) is arranged on the drive shaft (5) to rotate with the drive shaft (5) and the second magnet arrangement (37) is arranged at the circumference of the drive shaft (5) in a non-rotating position with respect to the drive axis (7).

7. Driving device according to claim 6, characterized in that the second magnet arrangement (37) is mounted moveable with respect to the drive shaft (5) along the drive axis (7).

8. Driving device according to claim 4 or 5, characterized in that the first magnet arrangement (35) is arranged on the driven component (3, 48, 69) and/or a transmission element (9, 1 1 , 13, 17, 19, 21 ) to move with the driven component and/or the transmission element (9, 11 , 13, 17, 19, 21 ), and the second magnet arrangement (37) is arranged in a stationary position along a movement path of the driven component (3) and/or the transmission element (9, 11 , 13, 17, 19, 21 ).

9. Driving device according to any one of claims 1 to 8, characterized in that the first magnet arrangement (35) comprises at least two effective magnetic poles, wherein in particular at least two magnetic poles of the first magnet arrangement (35) differ in at least one of a polarity, a magnitude, a size, and/or in that gaps between adjacent magnetic poles differ in size.

10. Driving device according to any one of claims 1 to 9, characterized in that the second magnet arrangement (37) comprises at least two effective magnetic poles, wherein in particular at least two magnetic poles of the second magnet arrangement (37) differ in at least one of a polarity, a magnitude, a size, and/or in that gaps between adjacent magnetic poles differ in size.

1 1. Driving device according to any one of claims 1 to 10, characterized in that the at least one actuator (31 ) is an electric motor.

12. Driving device according to any one of claims 1 to 11 , wherein the driving device (1 , 101 , 201 , 301 , 401 , 501 , 601 , 701 , 801 , 901 , 1001 , 1 101 ) is selected from the group comprising at least a harness drive, a gripper drive, a sley drive, a selvage drive.

13. Assembly group of a weaving machine comprising a driving device according to claims 1 to 12 and a driven component (3, 48, 69) connected to the drive shaft (5) of the driving device.

14. Weaving machine comprising a driving device according to claims 1 to 12.

15. Method for driving a drive shaft (5) in a weaving machine, wherein by means of at least one actuator (31 ) a drive torque is exerted on the drive shaft (5) to rotate the drive shaft (5) about a drive axis (7), wherein a required drive torque varies with an angular position of the drive shaft (5), and wherein in at least one angular position of the drive shaft (5) an assisting drive torque is exerted on the drive shaft (5), wherein the drive torque of the at least one actuator (31 ) and the assisting drive torque of the assisting device (33) provide a resulting drive torque, wherein the assisting drive torque is exerted by an attractive and/or repulsive force between a first magnet arrangement (35) comprising at least one first permanent magnet (135, 136) and a second magnet arrangement (37) comprising at least one second permanent magnet (137, 138), wherein the first magnet arrangement (35) and the second magnet arrangement (37) are displaced relative to one another with the rotation of the drive shaft (5).

Description:
Driving Device for a Weaving Machine with Assisting Device

TECHNICAL FIELD AND PRIOR ART

[0001] The invention relates to a driving device for a weaving machine, the driving device comprising a drive shaft with a drive axis, at least one actuator exerting a drive torque on the drive shaft to rotate the drive shaft about the drive axis, and an assisting device. The invention further relates to an assembly group of a weaving machine, to a weaving machine comprising a driving device, and to a method for driving a drive shaft in a weaving machine.

[0002] A weaving machine comprises several driving devices, for example a harness drive, a gripper drive, a sley drive, a selvage device drive, and other drives. The driving device for example comprises a drive shaft to which components or elements to be driven are coupled. The components or elements are referred to as driven components or driven elements. Several of these driven components are driven to carry out non-continuous motions: for example a sley unit, which is moved to-and-fro, healds or other shed forming means, which are moved up and down, and grippers, which are moved into-and-out of the shed.

[0003] The drive shaft of such a driving device in one embodiment rotates to-and-fro. This movement is also referred to as oscillation. In other embodiments, the drive shaft is rotated through 360°, wherein in normal operation the drive shaft is rotated continuously or step-wise in either one of the two directions of rotation. This movement is also referred to as complete rotation, i.e. over a complete revolution. The driving device comprises an actuator exerting a drive torque on the drive shaft for rotating the drive shaft. The actuator is coupled directly or via a gearing system to the drive shaft. Several driving devices in one embodiment are provided with a common actuator. In other embodiments, each driving device is provided with a separate actuator. Due to the non-continuous motion, for example to-and-fro motion of components driven by a drive shaft of the driving device, a required drive torque varies with an angular position of the drive shaft.

[0004] For producing an oscillating or to-and-fro motion of a driven component in a weaving machine, WO 2005/010257 A1 discloses a driving device comprising a drive source, an electromagnetic energy accumulator, which is assigned to the driven component and/or to the drive source and which is provided for accumulating potential energy during at least one portion of the to-and-fro motion of the driven component, and a control device for controlling at least the energy accumulator and/or the drive source according to measured and/or predetermined parameters for the course of motion of the driven component. The electromagnetic accumulator comprises a magnetic pole pair, wherein at least one of the magnetic poles is an electromagnetic pole. The natural frequency of the to-and-fro motion depends on the current applied to the electromagnetic accumulator and to the mass of the driven component. In one embodiment, the drive source only provides energy to compensate for friction losses. In other embodiments, the drive source is operated for causing a forced oscillation of the driven component.

SUMMARY OF THE INVENTION

[0005] It is an object of the invention to provide a driving device for a weaving machine with reduced energy consumption. It is further the object of the invention to provide an assembly group of a weaving machine and a weaving machine comprising a driving device, and a method for driving a drive shaft in a weaving machine.

[0006] These objects are solved by the driving device with the features of claim 1 , the assembly group of a weaving machine with the features of claim 13, the weaving machine with the features of claim 14 and the method with the features of claim 15. Preferred embodiments are defined in the dependent claims. The invention offers the advantage that a passive assisting device, which does not require any energy supply, exerts an assisting drive torque in at least one angular position on the drive shaft, so that the drive torque, which has to be exerted by the actuator, can have less variation. The person skilled in the art can arrange the assisting device in a suitable position, such that due to the assisting drive torque provided by the passive assisting device, the overall energy consumption is reduced.

[0007] According to a first aspect, a driving device is provided, the driving device comprising a drive shaft with a drive axis, at least one actuator exerting a drive torque on the drive shaft to rotate the drive shaft about the drive axis, wherein a required drive torque varies with an angular position of the drive shaft, and a passive assisting device with a first magnet arrangement comprising at least one first permanent magnet and a second magnet arrangement comprising at least one second permanent magnet, wherein the first magnet arrangement and the second magnet arrangement are displaced relative to one another with the rotation of the drive shaft, and wherein in at least one angular position of the drive shaft an attractive and/or repulsive force between the first magnet arrangement and the second magnet arrangement exerts an assisting drive torque on the drive shaft, wherein the drive torque of the at least one actuator and the assisting drive torque of the assisting device provide a resulting drive torque on the drive shaft. [0008] In the context of the application, the expression“passive assisting device” defines a device, which for its operation does not require an external energy supply. In contrast, an actuator requires an external energy supply. The passive assisting device with permanent magnets is also referred to as magnetic spring device. By means of the passive assisting device an assisting drive torque is provided in at least one angular position. The assisting drive torque can act in the same direction as the drive torque exerted by the actuator or in an opposite direction. Hence, the drive torque to be provided by the at least one actuator in such an angular position for causing a desired movement of the drive shaft is different to the drive torque to be provided in the absence of the assisting drive torque. For example, the first magnet arrangement and the second magnet arrangement are arranged such that an attractive force is exerted on the drive shaft when the drive shaft approaches a first angular position. In embodiments of the invention, this attractive force will exert a torque on the drive shaft in a desired movement direction of the drive shaft, also referred to as positive torque, when the drive shaft approaches the first angular position. In alternative or in addition, in embodiments of the invention, this attractive force will further exert a torque on the drive shaft directed opposite to the desired movement direction of the drive shaft, also referred to as negative torque, when the drive shaft departs from the first angular position. By suitable arrangement and construction of the first magnet arrangement and the second magnet arrangement, a positive torque is exerted in an angular position requiring a higher drive torque for moving the driven component and/or a negative torque is exerted in an angular position requiring a lower drive torque for moving the driven component. In result, in particular in a device with a drive shaft performing complete rotations, the drive torque to be exerted by the actuator can have less variation than in devices without passive assisting devices, thereby, an energy consumption of the actuator and, thus, the driving device can be reduced.

[0009] The first magnet arrangement and the second magnet arrangement are in embodiments of the invention configured, such that in all angular positions an assisting drive torque is lower than a maximum required drive torque for causing a desired rotation of the drive shaft. For example the first magnet arrangement and the second magnet arrangement are configured, such that a maximum assisting drive torque is less than 40% of the maximum required drive torque, or even less than 20% of the maximum required drive torque. In case the drive shaft is rotated through 360°, depending on the arrangement and construction of the first magnet arrangement and the second magnet arrangement, a speed of the drive shaft can be influenced to have less variations compared to driving devices not equipped with an assisting device.

[0010] With the movement of the drive shaft, the first magnet arrangement and the second magnet arrangement are displaced relative to one another. In one embodiment, the first magnet arrangement comprises at least one first magnetic pole and the second magnet arrangement comprises at least one second magnetic pole, which is of opposite polarity to the at least one first magnetic pole, wherein within a movement range of the drive shaft the first magnet arrangement and the second magnet arrangement are displaced relative to one another to form at least one stable magnetic equilibrium point, wherein by means of the at least one actuator the first magnet arrangement and the second magnet arrangement are moved relative to each other out of the at least one stable magnetic equilibrium point. In the context of the application, a stable magnetic equilibrium point is referred to as a position, in which magnetic poles of opposite polarity are approached as far as possible. Hence, when moving the first magnet arrangement and the second magnet arrangement relative to each other out of the stable magnetic equilibrium point, the attractive forces between the magnetic poles of opposite polarity act against the movement, i.e. the passive assisting device exerts a negative torque. In addition, within the movement range of the drive shaft, the first magnet arrangement and the second magnet arrangement may be placed to form at least one unstable magnetic equilibrium point, in which forces exerted by the passive assistance device are balanced, i.e. the assisting drive torque in this position is zero. If by means of the at least one actuator the first magnet arrangement and the second magnet arrangement are moved relative to each other out of the at least one unstable magnetic equilibrium point, immediately after the unstable magnetic equilibrium point has been left, the passive assistance device exerts an accelerating assisting drive torque.

[0011 ] A magnetic flux field is generated between the first magnet arrangement and the second magnet arrangement, wherein in preferred embodiments, the first magnet arrangement and the second magnet arrangement are displaced relative to one another in a direction transverse to the magnetic flux field generated.

[0012] In one embodiment, the drive shaft is drivingly connectable to at least one driven component to move the at least one driven component to-and-fro along a movement path and/or to rotate at least one driven component about an axis along a circumferential movement path upon rotation of the drive shaft. The driven component for example is a heald frame moved up-and-down with the movement of the drive shaft of the driving device, a gripper moved by a rapier, which rapier is drivingly connected to the drive shaft of the driving device, a reed mounted on a sley beam or any other element of a weaving machine. The movement path along which the driven component performs a to-and-fro movement can be either linear, for example a to-and-fro movement of a gripper or a heald frame, or along a curved path, for example the to-and-fro movement of a reed. In some embodiments, the driven element is directly connected to the drive shaft. In other embodiments of the invention the drive shaft is drivingly connectable to the at least one driven component via at least one transmission element.

[0013] In one embodiment, upon its movement, the at least one driven component and/or the at least one transmission element exert or exerts a reaction torque on the drive shaft, wherein the first magnet arrangement and the second magnet arrangement are arranged such that at least in one angular position of the drive shaft the assisting drive torque exerted by the first magnet arrangement and the second magnet arrangement is counteractive to the reaction torque. In other words, in angular positions of the drive shaft, in which the reaction torque causes an acceleration of the drive shaft, the passive assisting device is used for braking the drive shaft. In other angular positions, in which the reaction torque causes a deceleration of the drive shaft, the passive assisting device is used for accelerating the drive shaft. This offers the advantage that this allows to limit the angular speed variations of the drive shaft, in case the drive shaft is rotated through 360°.

[0014] In one embodiment, the first magnet arrangement is arranged on the drive shaft to rotate with the drive shaft and the second magnet arrangement is arranged at the circumference of the drive shaft in a non-rotating position with respect to the drive axis. In other words, the second magnet arrangement comprising at least one second permanent magnet is not rotated with the drive shaft about the drive axis, but remains fixed in position with respect to the drive axis upon rotation of the drive shaft.

[0015] In accordance with the invention, the assisting device is a passive assisting device, wherein forces or torques applied depend on the number, magnitude, construction and arrangement of the first magnet arrangement and the second magnet arrangement. In order to adjust a magnitude or strength of forces or torques applied, in one embodiment, the second magnet arrangement is mounted moveable with respect to the drive shaft along the drive axis. Hence, by movement of the second magnet arrangement, the magnitude or strength of the force or torque applied by the passive assisting device can be adjusted.

[0016] In another embodiment, the first magnet arrangement is arranged on the driven component and/or a transmission element to move with the driven component and/or the transmission, and the second magnet arrangement is arranged in a stationary position along a movement path of the driven component and/or the transmission element. For example, the first magnet arrangement is arranged on a heald frame to move up-and-down with the heald frame, and/or on a transmission rod for a heald frame, to move to-and-fro with the transmission rod. [0017] The construction, strength and/or arrangement of the first magnet arrangement and the second magnet arrangement is chosen by the person skilled in the art to match the requirement of the associated device. In one embodiment, at least one of the first magnet arrangement and the second magnet arrangement comprises at least two effective magnetic poles. It is generally known to the person skilled in the art that permanent magnets are not monopoles. However, permanent magnets can be arranged so that only one of the magnetic poles is effective.

[0018] In one embodiment, the first magnet arrangement comprises at least two effective magnetic poles, wherein at least two magnetic poles of the first magnet arrangement differ in at least one of a polarity, a magnitude, a size, and/or gaps between adjacent magnetic poles differ in size. In alternative or in addition, in one embodiment the second magnet arrangement comprises at least two effective magnetic poles, wherein at least two magnetic poles of the second magnet arrangement differ in at least one of a polarity, a magnitude, a size, and/or in that gaps between adjacent magnetic poles differ in size.

[0019] The actuator in one embodiment is a pneumatic or hydraulic actuator. In preferred embodiments, the at least one actuator is an electric motor.

[0020] The driving device is for example selected from the group comprising at least a harness drive, a gripper drive, a sley drive, a selvage drive. The driving device in one embodiment is adapted for driving two or more driven components that differ in type, for example a gripper and a reed of a weaving machine.

[0021] According to a second aspect, an assembly group of a weaving machine comprising a driving device and a driven component is provided.

[0022] According to a third aspect, a weaving machine comprising a driving device is provided.

[0023] According to a fourth aspect, a method for driving a drive shaft in a weaving machine is provided, wherein by means of at least one actuator a drive torque is exerted on the drive shaft to rotate the drive shaft about a drive axis, wherein a required drive torque varies with an angular position of the drive shaft, and wherein in at least one angular position of the drive shaft an assisting drive torque is exerted on the drive shaft, wherein the drive torque of the at least one actuator and the assisting drive torque of the assisting device provide a resulting drive torque, wherein the assisting drive torque is exerted by an attractive and/or repulsive force between a first magnet arrangement comprising at least one first permanent magnet and a second magnet arrangement comprising at least one second permanent magnet, wherein the first magnet arrangement and the second magnet arrangement are displaced relative to one another with the rotation of the drive shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In the following, embodiments of the invention will be described in detail with reference to the drawings. Throughout the drawings, the same elements will be denoted by the same reference numerals.

Fig. 1 shows a driving device, namely a harness drive, of a weaving machine according to an embodiment of the invention;

Fig. 2 shows a detail of the harness drive of Fig. 1 with a drive shaft arranged in a first angular position;

Fig. 3 shows the detail of the harness drive of Fig. 2 with a drive shaft arranged in a second angular position;

Fig. 4 shows in a perspective view a detail of the harness drive of Fig. 1 with a drive shaft arranged in a first operation position; Fig. 5 shows in a perspective view the detail of the harness drive of Fig. 4 with a drive shaft arranged in a second operation position;

Fig. 6 shows a driving device, namely a sley drive, of a weaving machine according to an embodiment of the invention in a first angular position of a drive shaft;

Fig. 7 shows the sley drive of Fig. 6 in a second angular position of the drive shaft; Fig. 8 shows the sley drive of Fig. 6 in a third angular position of the drive shaft;

Fig. 9 shows a driving device of a weaving machine according to an embodiment of the invention in a first angular position of the drive shaft;

Fig. 10 shows the driving device of Fig. 9 in a second angular position of the drive shaft; Fig. 11 shows the driving device of Fig. 9 in a perspective view in the first angular position of the drive shaft;

Fig. 12 shows the driving device of Fig. 9 in a perspective view in a third angular position of the drive shaft; Fig. 13 shows a driving device, namely a harness drive, of a weaving machine according to an embodiment of the invention in a first angular position of the drive shaft;

Fig. 14 shows the harness drive of Fig. 13 in a second angular position of the drive shaft;

Fig. 15 shows a driving device, namely a harness drive, of a weaving machine according to another embodiment of the invention in a first angular position of the drive shaft; Fig. 16 shows the harness drive of Fig. 15 in a second angular position of the drive shaft; Fig. 17 shows a driving device, namely a sley drive, of a weaving machine according to another embodiment of the invention in a first angular position;

Fig. 18 shows the sley drive of Fig. 17 in a second angular position;

Fig. 19 shows a driving device, namely a gripper drive, of a weaving machine according to an embodiment of the invention in a first angular position;

Fig. 20 shows the gripper drive of Fig. 19 in a second angular position;

Fig. 21 shows a driving device, namely a harness drive, of a weaving machine according to another embodiment of the invention in a first angular position;

Fig. 22 shows the harness drive of Fig. 21 in a second angular position; Fig. 23 shows a driving device, namely a sley drive, of a weaving machine according to another embodiment of the invention in a first angular position;

Fig. 24 shows the sley drive of Fig. 23 in a second angular position; Fig. 25 shows a perspective view of a sley drive similar to the sley drive of Fig. 23 in the second angular position;

Fig. 26 shows a driving device, namely a gripper drive, of a weaving machine according to an embodiment of the invention in a first angular position;

Fig. 27 shows the gripper drive of Fig. 26 in a second angular position;

Fig. 28 shows the gripper drive of Fig. 26 in a third angular position;

Fig. 29 shows a driving device, namely a gripper drive, of a weaving machine according to an embodiment of the invention in a first angular position; and

Fig. 30 shows the gripper drive of Fig. 29 in a second angular position. DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0025] Fig. 1 shows a driving device, namely a harness drive 1 , of a weaving machine according to an embodiment of the invention. Figs. 2 to 5 show details of the harness drive 1 of Fig. 1. Such a harness drive 1 is shown in WO 2017032556 A1 of the applicant, which is herewith incorporated by reference. [0026] A first driven component in the form of a heald frame 3 is coupled to the harness drive 1.

The harness drive 1 shown in Figs. 1 to 5 is part of a shed forming device, which comprises a number of harness drives 1 and an equal number of heald frames 3, wherein each heald frame 3 is driven by an associated harness drive 1.

[0027] The shown harness drive 1 for driving the heald frame 3 comprises a drive shaft 5 rotating about a drive axis 7, a first transmission element in the form of a crank 9 (see Figs. 2 and 3) mounted to the drive shaft 5, a second transmission element in the form of a coupling rod 11 , and a swivel lever 13. The swivel lever 13 is swivelable to-and-fro about a swivel axis 15 between an upper position and a lower position.

[0028] The harness drive 1 further comprises a second swivel lever 17, swivelable to-and-fro about a second swivel axis 18 between an upper position and a lower position. The second swivel lever 17 is connected to the swivel lever 13 by means of a transmission element in the form of a coupling rod 19 and driven by the swivel lever 13 to conjointly move with the swivel lever 13. The heald frame 3 is connected to each of the swivel levers 13, 17 by means of a transmission element in the form of a connecting assembly comprising a coupling element 20 and a lifting rod 21. The first swivel lever 13 and the second swivel lever 17 are also transmission elements. The drive axis 5 and the swivel axis 15, 18 extend in parallel.

[0029] The coupling rod 11 of the harness drive 1 is linked to the crank 9 by a first hinged joint 23 (see Figs. 2 and 3), which first hinged joint 23 is eccentric to the drive axis 7. Further, the coupling rod 1 1 is linked to a connecting element 25 by a second hinged joint 27, which connecting element 25 is attached to the swivel lever 13.

[0030] The drive shaft 5 is mounted rotatably about the drive axis 7 in a fixed position in a housing 29. The housing 29 in use is arranged stationary at a weaving machine, for example mounted to a frame (not shown) of the weaving machine. The driving device 1 comprises an actuator 31 , which in the embodiment shown is part of a motor unit 32 (not shown in detail). In the embodiment shown, one actuator 31 is assigned to each harness drive 1 for driving the drive shaft 5 to rotate about the drive axis 7. In other embodiments, several harness drives share one common actuator. With the rotation of the drive shaft 5, the heald frame 3 is moved up-and-down between the upper position and the lower position, and a required drive torque for moving the heald frame 3 varies with an angular position of the drive shaft 5.

[0031] The harness drive 1 further comprises a passive assisting device 33 (see Figs. 2 to 5) with a first magnet arrangement 35 and a second magnet arrangement 37. The first magnet arrangement 35 is arranged on the drive shaft 5 to rotate with the drive shaft 5. The first magnet arrangement 35 comprises several permanent magnets 135, 136 with four magnetic poles, which are either a magnetic north pole or a magnetic south pole. The person skilled in the art will understand that all magnetic north poles and magnetic south poles can be swapped without any technical effect. In the figures, opposite poles are indicated by different patterns. The second magnet arrangement 37 is mounted to the housing 29 in a non-rotating or rotationally fixed position with respect to the drive axis 7. The second magnet arrangement 37 also comprises several permanent magnets 137, 138 with four magnetic poles, which are either a magnetic north pole or a magnetic south pole.

[0032] In the figures, each permanent magnet 135, 136, 137, 138 is depicted as being a hypothetical magnetic monopole. The person skilled in the art knows that each permanent magnet has a magnetic north pole and a magnetic south pole. In one embodiment, each permanent magnet 135, 136, 137, 138 is arranged such that only one of its magnetic poles is effective, hence each magnet arrangement having four magnetic poles comprises four permanent magnets. In other embodiments, both opposite magnetic poles of one permanent magnet 135, 136, 137, 138 are arranged to be effective. For example, the four magnetic poles of the first magnet arrangement 35 in one embodiment are provided on two semi-circular shaped permanent magnets and/or the four magnetic poles of the second magnet arrangement 37 are provided on two semi-circular shaped permanent magnets.

[0033] In use, the drive shaft 5 is driven to rotate about the drive axis 7 by means of the actuator 31 of the motor unit 32, wherein the first magnet arrangement 35 rotates together with the drive shaft 5 about the drive axis 7. Thereby, the first magnet arrangement 35 is displaced relative to the second magnet arrangement 37 with the rotation of the drive shaft 5. With the rotation, attractive and/or repulsive forces between the permanent magnets 135, 136 of the first magnet arrangement 35 and the permanent magnets 137, 138 of the second magnet arrangement 37 exert a variable assisting drive torque on the drive shaft 5, the direction and strength of which depends on the relative angular position of the drive shaft 5 carrying the first magnet arrangement 35 with respect to the second magnet arrangement 37. The drive torque of the actuator 31 of the motor unit 32 and the assisting drive torque of the passive assisting device 33 together provide a resulting drive torque on the drive shaft 5.

[0034] As best seen in Figs. 4 and 5, the second magnet arrangement 37 in the embodiment shown is mounted in a magnet housing 39. In the embodiment shown, the magnet housing 39 is mounted moveable with respect to the drive shaft 5 along an axial direction of the drive shaft 5 by means of two bars 41 , wherein an additional actuator device 40 is provided for moving the magnet housing 39 with the second magnet arrangement 37 along the axial direction of the drive shaft 5. Hence, by moving the second magnet arrangement 37 along the axial direction of the drive shaft 5, a strength or magnitude of the drive torque exerted by the passive assisting device 33 can be adjusted. The additional actuator device 40 comprises for example a hydraulic or pneumatic linear actuator (not shown in detail) comprising a piston 44.

[0035] In the embodiment shown in Figs. 1 to 5, the first magnet arrangement 35 and the second magnet arrangement 37 each comprise two magnetic poles of a first magnetic polarity and two magnetic poles of an opposite second magnetic polarity, which are evenly distributed about the circumference, so that each magnetic pole occupies one sector of 90°.

[0036] In the angular position of the drive shaft 5 shown in Fig. 2, the magnetic poles of the first magnetic polarity of the first magnet arrangement 35 are arranged opposite to the magnetic poles of the first magnetic polarity of the second magnet arrangement 37 and the magnetic poles of the second magnetic polarity of the first magnet arrangement 35 are arranged opposite to the magnetic poles of the second magnetic polarity of the second magnet arrangement 37. In this angular position, repulsive and attractive forces balance each other and this angular position is an unstable magnetic equilibrium point for example associated with a lower position of the heald frame 3. When exerting a drive torque by means of the actuator 31 of the motor unit 32, the drive shaft 5 is driven to rotate for example in a counterclockwise direction, wherein after the drive shaft 5 is rotated out of the unstable magnetic equilibrium point, the repulsive and attractive forces between the magnetic poles exert a positive assisting drive torque, which is acting on the drive shaft 5 in the counterclockwise direction, i.e. in the movement direction of drive shaft 5. Hence, the torque applied by the actuator 31 for causing that movement can be reduced. After the drive shaft 5 is rotated by 90°, a stable magnetic equilibrium point of the passive assisting device 33 is reached as shown in Fig. 3. When further driving the drive shaft 5 to rotate counterclockwise by means of the actuator 31 of the motor unit 32, the repulsive and attractive forces between the magnetic poles exert a negative assisting drive torque, i.e. acting in the direction opposite to the movement direction of the drive shaft 5 until again after a rotation about 90° a further unstable magnetic equilibrium point is reached. When further driving the drive shaft 5 to rotate counterclockwise by means of the actuator 31 of the motor unit 32 out of the unstable equilibrium point, the repulsive and attractive forces between the magnetic poles again exert a positive assisting drive torque on the drive shaft 5.

[0037] Figs. 6 to 8 show a further driving device with a rotating drive shaft 5, wherein for the same or similar elements the same reference numbers are used. More particular, Figs. 6 to 8 show a driving device, namely a sley drive 101 of a weaving machine in a first angular position, a second angular position, and a third angular position of the drive shaft 5, respectively.

[0038] The sley drive 101 shown in Figs. 6 to 8 is used for driving a sley unit 42 comprising several sley levers 45, which are carrying a sley beam 43 with a reed 48, to rotate to-and-fro about a sley lever axis 47. For sake of clarity, a fabric 80 and two sheets of warps 81 , 82 are shown, as well as a part of a frame 56 of the weaving machine and a fabric support 54 mounted to the frame 56 of the weaving machine. In this embodiment, a second driven component in the form of a reed 48 is coupled to the sley drive 101.

[0039] In the embodiment shown, the sley drive 101 comprises two conjugated cams 49, 51. The cams 49, 51 are fixedly mounted on the drive shaft 5 to rotate conjointly with the drive shaft 5 about the drive axis 7. The sley drive 101 further comprises a fork element 53 having two support arms 55, which together with several sley levers 45 are fixedly mounted on a sley shaft 57 to pivot conjointly about the sley lever axis 47. At the distal ends of the support arms 55, rollers 59 are provided. [0040] The sley drive 101 comprises an actuator (not shown) for driving the drive shaft 5 to rotate about the drive axis 7, thereby causing the sley levers 45 with the sley beam 43 to pivot to-and-fro about the sley lever axis 47. The actuator is for example a main actuator of a weaving machine, in particular a main motor, or an actuator only associated with the sley drive 101.

[0041] The sley drive 101 further comprises a first magnet arrangement 35 comprising one permanent magnet 136, which is mounted to the drive shaft 5 to rotate with the drive shaft 5. Further, a second magnet arrangement 37 is provided comprising two permanent magnets 137, which are arranged in a rotationally fixed position with respect to the drive shaft 5, for example in a magnet housing 39 as shown in Figs. 4 and 5.

[0042] In the embodiment shown, the effective magnetic poles of the two permanent magnets 137 of the second magnet arrangement 37 have the same magnetic polarity and have the opposite polarity of the effective magnetic pole of the permanent magnet 136 of the first magnet arrangement 35. In the embodiment shown, each permanent magnet 136, 137 is arranged in a sector of 60°, wherein the two permanent magnets 137 of the second magnet arrangement 37 are offset by a sector of 60°.

[0043] In the angular position of the drive shaft 5 shown in Fig. 6, the permanent magnet 136 of the first magnet arrangement 35 is arranged in the sector between the two permanent magnets 137 of the second magnet arrangement 37. The two effective magnetic poles of the permanent magnets 137 of the second magnet arrangement 37 cause at least essentially identical attractive forces and the position shown in Fig. 6 is an unstable equilibrium point. The configuration is for example associated with the beat-up position of the sley levers 45. When rotating the drive shaft 5 to thereby rotate the sley unit 42 clockwise in the drawing view, the magnetic pole of the permanent magnets 137 of the second magnet arrangement 37, towards which the permanent magnet 136 of the first magnet arrangement 35 is rotated, exerts an attractive force causing a positive assisting drive force on the drive shaft 5 in the movement direction of the drive shaft 5 until the stable equilibrium point shown in Fig. 7 is reached, in which stable equilibrium point the magnetic pole of the permanent magnet 136 of the first magnet arrangement 35 is arranged opposite to the magnetic pole of one of the permanent magnets 137 of the second magnet arrangement 37. By exerting a drive torque by means of an actuator (not shown) on the drive shaft 5, the drive shaft 5 is further driven to thereby rotate the sley unit 42 clockwise against the attractive forces between the magnetic poles 136, 137, which exert a negative assisting drive torque acting against the movement direction of the drive shaft 5 until again after a rotation about 180° from the initial position, a further unstable equilibrium point is reached as shown in Fig. 8. [0044] Figs. 9 to 12 show two further driving device, namely a sley drive 201 and a gripper drive 301 with a common rotating drive shaft 5, wherein for the same or similar elements the same reference numbers are used. More particular, Figs. 9 to 12 show a sley drive 201 of a weaving machine for moving a reed 48 and Figs. 11 and 12 additionally show a gripper drive 301 of a weaving machine for moving a rapier. The sley drive 201 and the gripper drive 301 are driven simultaneously by rotating the common drive shaft 5.

[0045] The two driving devices of Figs. 9 to 12 comprise a common actuator (not shown) for driving the drive shaft 5 to rotate about the drive axis 7, thereby causing, as shown in Figs. 9 and 10, the sley unit 42 with the reed 48 to pivot to-and-fro about a sley lever axis 47, and, as shown in Figs. 11 and 12, a rapier unit 61 to move a gripper into and out of a shed. The sley unit 42 comprises two conjugated cams 49, 51 that are fixedly mounted on the shaft 50 rotating about an axis 52 and driven by the drive shaft 5. A sley unit 42 for moving a reed 48 is known from EP 0726345 A1 of the applicant, which is incorporated herewith by reference. A rapier unit 61 for moving a gripper is known from DE 10346227 A1 of the applicant, which is incorporated herewith by reference.

[0046] The sley drive 201 for moving the reed 48 comprises a first magnet set 202 and the gripper drive 301 for moving the rapier comprises a second magnet set 203, with each set 202, 203 comprising a first magnet arrangement 35 and a second magnet arrangement 37.

[0047] The first magnet set 202 is shown in Figs. 9 and 10 and has a first magnet arrangement 35 comprising one first permanent magnet 135 with a first effective magnetic pole, which is mounted to the drive shaft 5 to rotate with the drive shaft 5, and a second magnet arrangement 37 comprising two second permanent magnets 138 forming two effective magnetic poles, which are arranged in a rotationally fixed position with respect to the drive axis 7.

[0048] In the embodiment shown, the two magnetic poles of the second permanent magnets 138 of the second magnet arrangement 37 have the same magnetic polarity and have the opposite polarity of the magnetic pole of the first permanent magnet 135 of the first magnet arrangement 35, wherein the magnetic poles could be either magnetic south poles or magnetic north poles. In the embodiment shown, each magnetic pole is arranged in a sector of 30°, wherein the two magnetic poles of the second permanent magnets 138 of the second magnet arrangement 37 are offset by a sector of 30°.

[0049] In the angular position of the drive shaft 5 shown in Fig. 9, the first permanent magnet 135 of the first magnet arrangement 35 is arranged in the sector between the two permanent magnets 138 of the second magnet arrangement 37. The two magnetic poles of the second permanent magnets 138 of the second magnet arrangement 37 cause at least essentially identical attractive forces and the position shown in Fig. 9 is an unstable equilibrium point. The configuration is for example associated with the beat-up position of the sley unit 42. When rotating the drive shaft 5 counterclockwise, the second permanent magnets 138 of the second magnet arrangement 37, towards which the first permanent magnet 135 of the first magnet arrangement 35 is rotated, exert an attractive force causing a positive assisting drive force on the drive shaft 5 acting in the movement direction until the stable equilibrium point is reached in which the first permanent magnet 135 of the first magnet arrangement 35 is arranged opposite to one of the second permanent magnets 138 of the second magnet arrangement 37. By exerting a drive torque by means of the actuator on the drive shaft 5, the drive shaft 5 is driven to rotate counterclockwise against the attractive forces between the permanent magnets 135, 138, which exert a negative assisting drive torque acting against the movement direction of the drive shaft 5 until again after a rotation about 180° from the beat-up position, a further unstable equilibrium point is reached.

[0050] The second magnet set 203 of the gripper drive 301 for moving the rapier (not shown) by means of a rapier unit 61 is shown in Figs. 1 1 and 12. The rapier unit 61 comprises a disc 63, which is driven to rotate about the axis 52 by means of the drive shaft 5. At a periphery of the disc 63 a toothed gear is provided, which is driven via a gear 71 rotating about a gear axis 72 by a gear 73 mounted on the drive shaft 5. A swivel element 65 is mounted with respect to the disc 63 to swivel with the rotation of the disc 63 to-and-fro about a swivel axis 67. As described in detail in DE 10346227 A1 , at a periphery of the swivel element 65 a toothed gear segment can be provided, which drives a wheel, which wheel is used for driving a rapier. The disc 63 drives the swivel element 65 via an arrangement 62 that is coupled to the disc 63 via a shaft 64 and a shaft support 66, The swivel element 65 can swivel about a swivel axis 68. A similar arrangement is disclosed in DE 10346227 A1.

[0051] The second magnet set 203 as shown in Figs. 11 and 12 has a first magnet arrangement 35 comprising four first permanent magnets 135, 136 forming four effective magnetic poles, which first magnet arrangement 35 is mounted to the drive shaft 5 to rotate with the drive shaft 5, and a second magnet arrangement 37 comprising four second permanent magnets 137, 138 forming four effective magnetic poles, which are arranged in a non-rotating or rotationally fixed position with respect to the drive shaft 5.

[0052] The first magnet set 202 assists the actuator in decelerating the sley unit 42 when it arrives at its front dead point or its rear dead point, which are unstable magnetic equilibrium points. The first magnet set 202 further assists the actuator in accelerating the sley unit 42 when it starts moving out of the front dead point or the rear dead point.

[0053] The second magnet set 203 assists the actuator in decelerating the rapier when it arrives at its front dead point or its rear dead point, which are unstable magnetic equilibrium points. The second magnet set 203 further assists the actuator in accelerating the rapier when it starts moving out of the front dead point or the rear dead point.

[0054] In an alternative embodiment, the first magnet set 202 and the second magnet set 203 are combined in one magnet set.

[0055] In each of the embodiments described above with reference to Figs. 1 to 12, the driving device 1 , 101 , 201 , 301 comprises a drive shaft 5 provided with a first magnet arrangement 35, wherein the drive shaft 5 with the first magnet arrangement 35 is arranged and driven to rotate through 360°, also referred to as driven to revolute. The second magnet arrangement 37 is arranged in a non-rotating position along the circumference of the drive shaft 5. A magnetic flux field is produced in a gap between the rotating first magnet arrangement 35 and the non- rotating stationary second magnet arrangement 37, in particular a magnetic flux field in a radial direction of the drive shaft 5. The first magnet arrangement 35 moves transverse to the magnetic flux field. Within the movement range of the drive shaft 5, i.e. within one full revolution or rotation by 360° of the drive shaft 5, the first magnet arrangement 35 and the second magnet arrangement 37 form at least one stable magnetic equilibrium point.

[0056] In the following, embodiments of the invention will be described with reference to Figs. 13 to 20, showing driving devices, namely a harness drive 401 , 501 of a weaving machine, a sley drive 601 of a weaving machine, and a gripper drive 701 of a weaving machine comprising a drive shaft 5, which is arranged and driven to rotate through 360°. A first magnet arrangement 35 of these driving devices is arranged on a driven component, which is driven by the drive shaft 5, and, with the rotation of the drive shaft 5, carries out a to-and-fro movement. The second magnet arrangement 37 is arranged in a stationary position along a movement path of the component carrying the first magnet arrangement.

[0057] Figs. 13 and 14 show a harness drive 401 of a weaving machine similar to the harness drive 1 shown in Figs. 1 to 5. For the same or similar elements, the same reference signs will be used. [0058] As described above, a heald frame 3 is coupled to the harness drive 401. For driving the heald frame 3 to move up-and-down, the harness drive 401 comprises a drive shaft 5 rotating about a drive axis 7, a first transmission element in the form of a crank 9 mounted to the drive shaft 5, a second transmission element in the form of a coupling rod 1 1 , and a swivel lever 13. The swivel lever 13 is swivelable to-and-fro about a swivel axis 15 between an upper position and a lower position.

[0059] The harness drive 401 further comprises a second swivel lever 17, swivelable to-and-fro about a second swivel axis 18 between an upper position and a lower position. The second swivel lever 17 is connected to the swivel lever 13 by means of a coupling rod 19 and driven by the swivel lever 13 to conjointly move with the swivel lever 13. The heald frame 3 is mounted to the swivel levers 13, 17 by means of a connecting assembly comprising coupling elements 20 and lifting rods 21.

[0060] The harness drive 401 comprises a passive assisting device 33 with a first magnet arrangement 35 and a second magnet arrangement 37. The first magnet arrangement 35 is mounted to the coupling rod 19 to move with the coupling rod 19 to-and-fro along a linear path. The second magnet arrangement 37 is mounted stationary in position for example on a frame 156 (only indicated schematically) of the weaving machine. The first magnet arrangement 35 comprises three first permanent magnets 136 having the same magnetic polarity. The second magnet arrangement 37 comprises three second permanent magnets 137 having the same magnetic polarity, wherein the magnetic polarity of the second permanent magnets 137 is opposite to that of the first permanent magnets 136. The first magnet arrangement 35 is moved with the coupling rod 19 transverse to a magnetic flux field generated between the moving first magnet arrangement 35 and the stationary second magnet arrangement 37.

[0061] In the angular position of the drive shaft 5 shown in Fig. 13, the first magnet arrangement 35 is displaced to the left with respect to the second magnet arrangement 37 and the passive assisting device exerts a force on the coupling rod 19 forcing the coupling rod 19 towards the right in the figure, i.e. in an intended movement direction of the coupling rod 19. Hence, the attractive forces between the first magnet arrangement 35 and the second magnet arrangement 37 exert a positive assisting drive torque, and the torque applied by the actuator 31 can be reduced.

[0062] After the drive shaft 5 is rotated by 90°, a stable magnetic equilibrium point of the passive assisting device 33 is reached as shown in Fig. 14, wherein the first magnet arrangement 35 is placed directly opposite the second magnet arrangement 37. When further driving the drive shaft 5 to rotate counterclockwise by means of an actuator (not shown in Figs. 13 and 14), the forces between the first magnet arrangement 35 and the second magnet arrangement 37 exert a negative assisting drive torque acting against the movement direction of the drive shaft 5.

[0063] Within the movement path of the drive shaft, i.e. within one revolution of the drive shaft 5, the first magnet arrangement 35 and the second magnet arrangement 37 form at least one stable magnetic equilibrium point.

[0064] Figs. 15 and 16 show a harness drive 501 of a weaving machine similar to the harness drive 401 shown in Figs. 13 and 14. For the same or similar elements, the same reference signs will be used, and for a detailed description of these elements reference is made to the description above.

[0065] The harness drive 501 also comprises a passive assisting device 33 with a first magnet arrangement 35 and a second magnet arrangement 37. In contrast to the embodiment shown in Figs. 13 and 14, the first magnet arrangement 35 is mounted to the swivel lever 13 to oscillate with the swivel lever 13 to-and-fro about the swivel axis 15. The second magnet arrangement 37 is mounted in a non-rotating position with respect to the swivel axis 15, for example in a magnet housing 39 as shown in Figs. 4 and 5, or on a frame (not shown) of the weaving machine. In the embodiment shown, the first magnet arrangement 35 comprises two first permanent magnets 135, 136 of opposite magnetic polarity. The second magnet arrangement 37 also comprises two second permanent magnets 137, 138 of opposite magnetic polarity. The two first permanent magnets 135, 136 and/or the two second permanent magnets 137, 138 in one embodiment are formed integrally as one semi-circular element.

[0066] In the angular position of the drive shaft 5 shown in Fig. 15, the first magnet arrangement 35 and the second magnet arrangement 37 form a stable magnetic equilibrium point. When driving the drive shaft 5 to rotate by means of an actuator (not shown in Figs. 15 and 16), the swivel lever 13 is rotated clockwise in the drawing view out of the stable magnetic equilibrium point towards the position as shown in Fig. 16, and the forces between the first magnet arrangement 35 and the second magnet arrangement 37 exert a negative assisting drive torque acting opposite to the movement direction of the swivel lever 13 and, thus, a movement of the drive shaft 5.

[0067] Figs. 17 and 18 show a sley drive 601 , similar to the sley drive 101 shown in Figs. 6 to 8. For the same or similar elements, the same reference signs will be used. The sley drive 601 is used for driving a sley unit 42 with a reed 48 to swivel to-and-fro about a sley lever axis 47. For this purpose, the sley unit 42 is driven by the drive shaft 5 (see Figs. 6 to 8, not shown in Figs. 17 and 18) about the sley lever axis 47.

[0068] The sley drive 601 comprises a passive assisting device 33 with a first magnet arrangement 35 and a second magnet arrangement 37. The first magnet arrangement 35 is mounted to the sley unit 42 to oscillate with the sley unit 42 to-and-fro about the sley lever axis 47. The second magnet arrangement 37 is mounted in a non-rotating position with respect to sley lever axis 47, for example in a magnet housing 39 as shown in Figs. 4 and 5. In the embodiment shown, the first magnet arrangement 35 comprises two first permanent magnets 135, 136 of opposite magnetic polarity. The second magnet arrangement 37 also comprises two second permanent magnets 137, 138 of opposite magnetic polarity. The two first permanent magnets 135, 136 and/or the two second permanent magnets 137, 138 in one embodiment are formed integrally as one semi-circular element.

[0069] In the position shown in Fig. 17, the first magnet arrangement 35 and the second magnet arrangement 37 are displaced out of a stable magnetic equilibrium point. When further driving the drive shaft 5 to thereby rotate the sley unit 42 clockwise by means of an actuator (not shown in Figs. 17 and 18), the forces between the first magnet arrangement 35 and the second magnet arrangement 37 exert a positive assisting drive torque acting in the movement direction of the sley unit 42 until the stable magnetic equilibrium point is reached. When moving the first magnet arrangement 35 by means of an actuator beyond the stable magnetic equilibrium point as shown in Fig. 18, the forces between the first magnet arrangement 35 and the second magnet arrangement 37 exert a negative assisting drive torque acting against the movement direction of the sley unit 42.

[0070] Figs. 19 and 20 show a driving device, namely a gripper drive 701 for moving a rapier (not shown) by means of a rapier unit 61 as shown and described in Figs. 11 and 12. The rapier unit 61 comprises a disc 63, wherein the drive shaft 5 (not shown in Figs 19, 20) is drivingly coupled to the disc 63 to rotate the disc 63. A swivel element 65 is mounted with respect to the disc 63 to swivel with the rotation of the disc 63 to-and-fro about a swivel axis 67.

[0071] The gripper drive 701 comprises a passive assisting device 33 with a first magnet arrangement 35 and a second magnet arrangement 37. The first magnet arrangement 35 is mounted to the swivel element 65 to oscillate with the swivel element 65 to-and-fro about the swivel axis 67. The second magnet arrangement 37 is mounted in a non-rotating position with respect to swivel axis 67, for example in a magnet housing 39 as shown in Figs. 4 and 5. In the embodiment shown, the first magnet arrangement 35 comprises two first permanent magnets 135, 136 of opposite magnetic polarity. The second magnet arrangement 37 also comprises two second permanent magnets 137, 138 of opposite magnetic polarity. The two first permanent magnets 135, 136 and/or the two second permanent magnets 137, 138 in one embodiment are formed integrally as one semi-circular element.

[0072] In the position shown in Fig. 19, the first magnet arrangement 35 and the second magnet arrangement 37 are displaced out of a stable magnetic equilibrium point. When further driving the drive shaft 5 to rotate the swivel element 65 clockwise by means of an actuator (not shown in Figs. 19 and 20), the forces between the first magnet arrangement 35 and the second magnet arrangement 37 exert a positive assisting drive torque acting in the desired movement direction of the swivel element 65 until the stable magnetic equilibrium point shown in Fig. 20 is reached. When moving the first magnet arrangement 35 by means of an actuator clockwise beyond the stable magnetic equilibrium point shown in Fig. 20 or counterclockwise from the stable magnetic equilibrium point shown in Fig. 20 towards the position shown in Fig. 19, the forces between the first magnet arrangement 35 and the second magnet arrangement 37 exert a negative assisting drive torque acting against the movement direction of the swivel element 65.

[0073] In the following, embodiments of the invention will be described with reference to Figs. 21 to 27, showing driving devices, namely a harness drive 801 , a sley drive 901 , and a gripper drive 1001 comprising a drive shaft 5, which is arranged and driven to oscillate, i.e. to rotate to- and-fro.

[0074] Figs. 21 and 22 show a harness drive 801 of a weaving machine similar to the harness drive 1 shown in Figs. 1 to 5. For the same or similar elements, the same reference signs will be used, and for a detailed description of these elements reference is made to the description above. A drive shaft 5 of the harness drive 801 is provided coaxially to the swivel axis 15 of the first swivel lever 13. The drive shaft 5 is driven by an actuator 31 (not shown in detail) to rotate to-and-fro about the drive axis 7, which coincides with the swivel axis 15. For example, the actuator 31 is designed as a controllable motor.

[0075] The harness drive 801 also comprises a passive assisting device 33 with a first magnet arrangement 35 and a second magnet arrangement 37. In contrast to the embodiment shown in Figs. 15 and 16, the first magnet arrangement 35 is mounted to the second swivel lever 17 to oscillate with the swivel lever 17 to-and-fro about the swivel axis 18. The second magnet arrangement 37 is mounted in a non-rotating position with respect to the swivel axis 18, for example in a magnet housing 39 as shown in Figs. 4 and 5, or on a frame (not shown) of the weaving machine. In the embodiment shown, the first magnet arrangement 35 comprises two first permanent magnets 135, 136 of opposite magnetic polarity. The second magnet arrangement 37 also comprises two second permanent magnets 137, 138 of opposite magnetic polarity. The two first permanent magnets 135, 136 and/or the two second permanent magnets 137, 138 in one embodiment are formed integrally as one semi-circular element. When moving the swivel lever 17 with the first magnet arrangement 35 by means of an actuator towards the stable magnetic equilibrium point shown in Fig. 22, the forces between the first magnet arrangement 35 and the second magnet arrangement 37 exert a positive assisting drive torque acting in the movement direction of the swivel lever 17.

[0076] Figs. 23 to 25 show a sley drive 901 for driving a sley unit 42 with a reed 48 to swivel to-and-fro about a sley lever axis 47. For this purpose, a drive shaft 5 is drivingly coupled to the sley unit 42, in particular is made in one piece with the sley shaft 57.

[0077] The sley drive 901 comprises an actuator 31 drivingly coupled to a drive shaft 5 for rotating the drive shaft 5 to-and-fro about the drive axis 7 for causing the sley beam 43 with the reed 48 to move to-and-fro, which drive axis 7 coincides with the sley lever axis 47. The sley drive 901 further comprises a passive assisting device 33 with a first magnet arrangement 35 and a second magnet arrangement 37. The first magnet arrangement 35 is mounted to the sley unit 42, in particular to the sley shaft 57 of the sley unit 42, to oscillate with the sley unit 42 to- and-fro about the sley lever axis 47. The second magnet arrangement 37 is mounted in a non- rotating position with respect to sley lever axis 47, for example in a magnet housing 39 as shown in Figs. 4 and 5. In the embodiment shown, the first magnet arrangement 35 comprises two first permanent magnets 135, 136 of opposite magnetic polarity. The second magnet arrangement 37 also comprises two second permanent magnets 137, 138 of opposite magnetic polarity. The two first permanent magnets 135, 136 and/or the two second permanent magnets 137, 138 in one embodiment are formed integrally as one semi-circular element.

[0078] The drive torque of the actuator 31 and the assisting drive torque of the assisting device 33 provide a resulting drive torque on the drive shaft 5 shown in Fig. 25, in particular on the drive shaft 57 drivingly coupled to the drive shaft 5, wherein the assisting device 33 either provides a positive assisting drive torque or a negative assisting drive torque, which are chosen so that the drive torque to be provided by the at least one actuator 31 can be more constant compared to devices not equipped with an assisting device 33. In the position shown in Fig. 23, the first magnet arrangement 35 and the second magnet arrangement 37 are displaced out of a stable magnetic equilibrium point. When driving the drive shaft 5 to rotate with the first magnet arrangement 35 clockwise by means of the actuator 31 , the forces between the first magnet arrangement 35 and the second magnet arrangement 37 exert a positive assisting drive torque acting in the desired movement direction of the drive shaft 5 until the stable magnetic equilibrium point shown is reached. When moving the drive shaft 5 with first magnet arrangement 35 by means of an actuator 31 clockwise beyond the stable magnetic equilibrium point into the position shown in Fig. 24, the forces between the first magnet arrangement 35 and the second magnet arrangement 37 exert a negative assisting drive torque acting against the movement direction of the drive shaft 5. Hence, the assisting drive torque can cause a deceleration of the drive shaft 5 even when a constant drive torque is applied by the actuator 31. After the dead end of the movement of the sley unit 42 is reached, the direction of the drive torque applied by the actuator 31 is reversed to move the drive shaft 5 counterclockwise. The assisting driving device 33 provides a positive assisting drive torque acting in the movement direction of the drive shaft 5 until the stable equilibrium point is reached. During a further counterclockwise movement beyond the stable equilibrium point, the the forces between the first magnet arrangement 35 and the second magnet arrangement 37 exert a negative assisting drive torque acting against the movement direction of the drive shaft 5.

[0079] In an alternative of Figs. 23 to 25, the polarity of all of the first permanent magnets 135, 136 and the second magnets 137, 138 of the sley drive 901 can be swapped.

[0080] Figs. 26 to 28 show a driving device, namely a gripper drive 1001 for moving a rapier (not shown) with a gripper (not shown) by means of a wheel 69. In this embodiment, a third driven component, for example in the form of a wheel 69 is coupled to the gripper drive 1001. The gripper drive 1001 comprises a drive shaft 5, which is driven to rotate to-and-fro about a drive axis 7 by means of an actuator 31. The drive shaft 5 is drivingly coupled to a swivel element 65 to rotate the swivel element 65 to-and-fro about a swivel axis 67 with the to-and-fro rotation of the drive shaft 5, wherein in the embodiment shown the swivel axis 67 coincides with the drive axis 7. At a periphery of the swivel element 65 a toothed gear segment 75 is provided, which drives the wheel 69 via a gear 76, which gear 76 is mounted to the wheel 69 via a gear shaft 77.

[0081] The gripper drive 1001 further comprises a passive assisting device 33 with a first magnet arrangement 35 and a second magnet arrangement 37. The first magnet arrangement 35 is mounted to the swivel element 65 to oscillate with the swivel element 65 about the swivel axis 67. The second magnet arrangement 37 is mounted in a non-rotating position with respect to swivel axis 67, for example in a magnet housing 39 as shown in Figs. 4 and 5. In the embodiment shown, the first magnet arrangement 35 comprises two first permanent magnets 135, 136 of opposite magnetic polarity. The second magnet arrangement 37 also comprises two second permanent magnets 137, 138 of opposite magnetic polarity. The two first permanent magnets 135, 136 and/or the two second permanent magnets 137, 138 in one embodiment are formed integrally as one semi-circular element.

[0082] Figs. 29 and 30 show a further driving device, namely a gripper drive 1 101 for moving a rapier (not shown) by means of a wheel 69, wherein for the same or similar elements the same reference numbers are used as in the embodiment of Figs. 26 to 28. The second magnet arrangement 37 is mounted in a magnet housing 79. The magnet housing 79 is arranged in a frame (not shown) of the weaving machine, so that the magnet housing 79 can rotate about the swivel axis 7, 67. In this way, the second magnet arrangement 37 can be rotated about the swivel axis 7, 67 by rotating the magnet housing 79. This allows to set the angular position of the second magnet arrangement 37 by setting the angular position of the magnet housing 79 with respect to a frame (not shown) of the weaving machine. Further, a setting device 74 is provided to rotate and to fix the magnet housing 79 with respect to the frame (not shown) of the weaving machine. In an example, the setting device 74 comprises a threaded element 84 of which an end is secured rotatable in an axial position with respect to a projection 78 of the housing 79. Further, a projection 85 is mounted fixed to the frame (not shown) of the weaving machine, which projection 85 comprises a threaded hole. By rotating the threaded element 84 in the threaded hole of a projection 85, the angular position of the housing 79 with the second magnet arrangement 37 can be set. Two possible angular positons of the housing 79 are shown respectively in Fig. 29 and Fig. 30. Further, a nut element 86 can be provided for fixing the threaded element 84 with respect to the projection 85, and thus also the position of the housing 79 with the projection 78 with respect to the frame (not shown) of the weaving machine. This arrangement allows to set the angular position of a stable magnetic equilibrium point of the passive assisting device 33.

[0083] In the embodiments shown in Figs. 1 to 14 and 21 to 30, the first magnet arrangement 35 is arranged on the drive shaft 5 to move with the drive shaft 5. In alternative embodiments, the assisting device is provided on a separate assisting device shaft, wherein a transmission, in particular a gear transmission, is provided between the assisting device shaft and the drive shaft 5 driven by the actuator 31. Such an embodiment is in particular advantageous for the embodiments shown in Figs. 21 to 30, wherein an amplitude of the oscillating movement of the assisting device shaft can be chosen larger or smaller than an amplitude of the oscillating movement of the drive shaft 5. [0084] It will be understood by the person skilled in the art that the embodiments described above are only exemplary embodiments. Various modifications are conceivable, for example by combining several passive devices and/or by combining passive devices with other actuator arrangements.