TECHNICAL FIELD AND PRIOR ART

The invention relates to a drive system for a weaving machine comprising a first drive gear wheel for driving a first group of elements, a second drive gear wheel for driving a second group of elements, a switching gear wheel, wherein the switching gear wheel is displaceable between a first position, in which the switching gear wheel is in drive connection with the first drive gear wheel and the second drive gear wheel, and a second position, in which the switching gear wheel is not in drive connection with the first drive gear wheel. The invention further relates to a weaving machine with such a drive system.

Such a drive system is shown for example in US 5617901 or US 7857011 , wherein a first drive gear wheel is used for driving a first group of elements including a sley drive and a second drive gear wheel is used for driving a second group of elements including a shed formation device. In normal operation, the switching gear wheel is in drive connection with the first drive gear wheel and the second drive gear wheel for driving the first group of elements and the second group of elements in synchronization. For a so-called pick finding, the switching gear wheel is displaced into the second position, in which the switching gear wheel is not in drive connection with the first group of elements, so that upon rotation of the switching gear wheel, the first drive gear wheel is not rotated.

The drive system shown in US 7857011 further comprises a holding element in the form of a gear wheel, which is axially displaceable with the switching gear wheel, wherein in the second position of the switching gear wheel, the holding element engages with the first drive gear wheel for holding the first drive gear wheel against rotation. In addition, during a standstill of the first group of elements and the second group of elements, it is known to keep the switching gear wheel in position by a main drive motor coupled thereto, wherein the main drive motor is driven in position modus and/or braked using a brake.

SUMMARY OF THE INVENTION

It is the object of the invention to provide a drive system and a weaving machine with an improved blocking device, which blocking device can be activated for blocking a rotation of the second drive gear wheel while the second drive gear wheel is in standstill. This object is solved by the drive system and the weaving machine with the features of claims 1 and 13. Preferred embodiments are defined in the dependent claims.

According to a first aspect, a drive system for a weaving machine is provided, which comprises a first drive gear wheel for driving a first group of elements, in particular including a sley device, a second drive gear wheel for driving a second group of elements, in particular including a shed formation device, a switching gear wheel, wherein the switching gear wheel is displaceable between a first position, in which the switching gear wheel is in drive connection with the first drive gear wheel and the second drive gear wheel, and a second position, in which the switching gear wheel is not in drive connection with the first drive gear wheel, and a blocking device, wherein the blocking device can be activated for blocking a rotation of the second drive gear wheel while the second drive gear wheel is in standstill, wherein the blocking device comprises a lever having a tooth for engaging with teeth of the second drive gear wheel, and wherein the lever is mounted swivellable about a swivel axis of the lever extending in parallel to the rotation axis of the second drive gear wheel between a blocking position, in which the tooth engages with the second drive gear wheel, and a rest position, in which the tooth is disengaged from the second drive gear wheel.

The blocking device comprising the lever mounted swivellable about the swivel axis extending in parallel to the rotation axis of the second drive gear is advantageous to block the second drive gear wheel against rotation even when large external forces are acting on the second drive gear wheel, wherein the second drive gear wheel exerts a large force on the lever. The design and arrangement are advantageous in that the tooth of the lever can easily engage or disengage with teeth of the second drive gear wheel as the tooth can move almost radially towards or away from the second drive gear wheel. This also allows that the tooth can easily enter between two teeth of the second drive gear wheel even when the tooth is not arranged fully centrally between these two teeth before engaging.

The invention is particularly advantageous when the second drive gear wheel is in drive connection with a jacquard system. When a jacquard system is in a standstill position, normally several warp threads are in the open shed position and exert a large force on the second drive gear wheel that needs to be kept in standstill.

Throughout this specification and the following claims, the indefinite article "a" or "an" means "one or more". Reference to a “first element" does not mandate presence of a “second element”. Further, the expressions “first” and “second” are only used to distinguish one element from another element and not to indicate any order of the elements. In embodiments, in the second position, in which the switching gear wheel is not in drive connection with the first drive gear wheel, the switching gear wheel is still in drive connection with the second drive gear wheel.

In an embodiment, a main drive motor is coupled to the second drive gear wheel, wherein the first drive gear wheel in normal operation is coupled to the main drive motor via the second drive gear wheel and the switching gear wheel. In other embodiments, the main drive motor is coupled to the switching gear wheel, wherein in normal operation the first drive gear wheel and the second drive gear wheel are coupled to the main drive motor via the switching gear wheel.

The first drive gear wheel, the second drive gear wheel and the switching gear wheel are individually or jointly also referred to as gear wheels.

In one embodiment, in the second position of the switching gear wheel, the switching gear wheel is offset from the first drive gear wheel in the direction of the rotation axis of the first drive gear wheel, so that for interrupting the drive connection teeth of the gear wheels are separated in the axial direction. In another embodiment, a teeth area of the first drive gear wheel is provided with at least one notch or clearance running over part of the axial length and several teeth, for example four to fifteen teeth, so that a drive connection is interrupted in case the switching gear wheel is arranged in the area of the at least one notch or clearance. As a result, an axial displacement of the switching gear wheel between the first position and the second position, and thus a required space for interrupting a drive connection between the switching gearwheel and the first drive gear wheel can be reduced.

The blocking device comprising the lever having at least one tooth for engaging with teeth of the second drive gear wheel allows to keep the second drive gear wheel in position despite any external forces acting on elements of the second group of elements during standstill of the second drive gear wheel. This allows keeping the second drive gear wheel in position, so that forces and subsequent bearing forces on the switching gear wheel in drive connection with the second drive gear wheel can be reduced, which forces could cause an unintended rotation of the switching gear wheel in drive connection with the second drive gear wheel and/or could cause friction forces between teeth of the switching gear wheel and teeth of the second drive gear wheel that counter an axial displacement of the switching gear wheel, thus, impede a displacement of the switching gear wheel with respect to the first drive gear wheel and the second drive gear wheel for displacing the switching gear wheel between the first position and the second position. In an embodiment, the tooth is provided at a side face of the lever facing the teeth of the second drive gear wheel. In other words, the tooth is arranged for gripping the teeth of the second drive gear wheel in a tooth cavity.

In an embodiment, for moving the lever, the blocking device comprises an excentre, which can be swiveled back-and-forth or rotated about an axis of rotation that is parallel to the swivel axis of the lever, wherein the excentre is driven using a piston that is mounted transversely to the axis of rotation of the excentre.

In another embodiment, the blocking device comprises an axially displaceable piston extending in parallel to the swivel axis of the lever, wherein the piston cooperates with the lever so that the lever is swivellable between the blocking position and the rest position by an axial displacement of the piston. As the piston is arranged in parallel to the swivel axis of the lever, such a blocking device can be manufactured compact in design.

In an embodiment, the lever is provided with a passage aperture offset from the swivel axis of the lever, wherein the piston extends through the passage aperture. By shifting the piston in parallel to the swivel axis of the lever, the lever is swiveled to engage or disengage with the second drive gear wheel.

For this purpose, in one embodiment, the passage aperture and the piston have opposing slanting surfaces.

In an embodiment, the piston forms part of a pneumatic actuator. In other embodiments, the piston forms part of a hydraulic actuator. The use of a hydraulic actuator allows a reliable movement of the piston back-and-forth and the application of high holding forces.

In an embodiment, a first end of the piston is mounted in a blocking device housing of the blocking device and a second end of the piston is mounted in a frame of the weaving machine. In an embodiment, a supply system for the hydraulic actuator is provided in the blocking device housing. The blocking device housing is fixable to a frame of the weaving machine, for example using bolts or screws.

In an embodiment, the blocking device comprises a sensor system for sensing whether or not the blocking device is activated, in particular for sensing whether or not the lever is in the blocking position. During a pick finding, the second group of elements is moved, wherein in particular the second group of elements is moved via the second drive gear wheel and the main drive in direct or indirect drive connection with the second drive gear wheel. For this purpose, the blocking device must be disengaged from the second drive gear wheel. In order to avoid that the main drive drives the second drive gear wheel while the blocking device is activated, the sensor system is provided.

In an embodiment, an output of the sensor system is displayed on a monitor of the weaving machine and/or transmitted to a control system of the weaving machine.

In an embodiment, the drive system comprises a holding element, which is axially displaceable with the switching gear wheel, wherein in the second position of the switching gear wheel, the holding element engages with the first drive gear wheel for holding the first drive gear wheel against rotation, and wherein in the first position of the switching gear wheel, the holding element is disengaged from the first drive gear wheel, and a displacement device for displacing the switching gear wheel and the holding element between the first position and the second position. In an embodiment, the holding element is a gear wheel in accordance with US 7857011 , which is herewith incorporated by reference.

In an embodiment, the switching gear wheel is arranged to be driven by the main drive motor. In an embodiment, the switching gear wheel can be disconnected from the main drive motor and manually driven or driven by an auxiliary drive motor during pick finding.

In an embodiment, a brake system is provided for braking the drive system, in particular a brake system for braking a shaft of the main drive motor. The brake system in an embodiment can be activated when stopping the weaving machine for a pick finding. After braking the drive system, the blocking device can be activated to engage with the second drive gear wheel. After the activation of the blocking device, the brake system can be deactivated.

As mentioned above, in embodiments, in the second position, the switching gear wheel is still in drive connection with the second drive gear wheel.

In case the second drive gear wheel is held against rotation using the main drive motor and/or the brake system during standstill, after an activation of the blocking device it is not necessary any more to hold the second drive gear wheel against rotation by the main drive motor and/or by the brake system, and it is avoided that the switching gear wheel is rotated relative to the first drive gear wheel and/or to the second drive gear wheel due to external forces acting on the second drive gear wheel, which relative rotation could otherwise cause high tooth forces and subsequent bearing forces when moving the switching gear wheel to the first position for a drive connection with the first drive gear wheel or when moving the switching gear wheel to the second position.

According to a second aspect, a weaving machine with a drive system having a blocking device as described above is provided.

In an embodiment, the weaving machine comprises a first drive gear wheel used for driving a first group of elements including a sley drive and a second drive gear wheel used for driving a second group of elements including a shed formation device, in particular a jacquard system.

BRIEF DESCRIPTION OF THE DRAWINGS

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 simplified perspective view of a drive system for a weaving machine comprising a blocking device in a first position of the switching gear wheel, while the blocking device is not activated.

FIG. 2 shows a simplified perspective view of the drive system of FIG. 1 in a first position of the switching gear wheel, while the blocking device is activated.

FIG. 3 shows a simplified perspective view of the drive system of FIG. 1 in a second position of the switching gear wheel, while the blocking device is activated.

FIG. 4 shows a simplified perspective view of the drive system of FIG. 1 in the second position of the switching gear wheel, while the blocking device is not activated.

FIG. 5 shows a blocking device housing with a frame of the weaving machine in a perspective view.

FIG. 6 shows a detail of the drive system of FIG. 1 with a blocking device housing in a perspective view.

FIG. 7 shows in a perspective view the blocking device and a part of the second drive gear wheel of the drive system of FIG. 1 , while the blocking device is activated. FIG. 8 shows in a perspective view the blocking device and a part of the second drive gear wheel of FIG. 7, while the blocking device is not activated.

FIG. 9 shows in a sectional view the blocking device and the second drive gear wheel, while the blocking device is not activated.

FIG. 10 shows in a sectional view the blocking device and the second drive gear wheel of FIG. 9, while the blocking device is activated.

FIG. 11 shows in a detail the actuator of the blocking device in cross section, while the blocking device is not activated.

FIG. 12 shows the lever of the blocking device in isolation.

FIG. 13 shows a view of a second embodiment of a blocking device in an activated state, while the blocking device is activated.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIGS. 1 to 4 show in simplified views a drive system 1 for a weaving machine (not shown) comprising a first drive gear wheel 2 for driving a first group of elements including a sley device (not shown), a second drive gear wheel 3 for driving a second group of elements including a shed formation device (not shown), a switching gear wheel 4, a holding element 5, a main drive motor 6 with a drive motor gear wheel 7 that engages the switching gear wheel 4, so that the switching gear wheel 4 can be driven to rotate by the main drive motor 6, a brake system 8 for braking the shaft 52 of the main drive motor 6 and the drive motor gear wheel 7, and a blocking device 9 for the second drive gear wheel 3. The shed formation device driven by the second drive gear wheel 3 can be a known cam system, a dobby system, or a jacquard system.

FIG. 5 shows in part the drive system 1 of FIG. 1 mounted to a weaving machine in a perspective view. FIG. 6 shows the drive system 1 of FIG. 1 with a blocking device housing 12 and a frame part 13 of a frame of the weaving machine in a perspective view. As shown in FIG. 5, the blocking device housing 12 is fixed with bolts 40 to an intermediate frame part 41 that is fixed to the frame part 13 using bolts (not shown).

The switching gear wheel 4 is displaceable between a first position shown in FIGS. 1 and 2, in which the switching gear wheel 4 is in drive connection with the first drive gear wheel 2 and the second drive gear wheel 3, and a second position shown in FIGS. 3 and 4, in which the switching gear wheel 4 is not in drive connection with the first drive gear wheel 2.

In the embodiment shown, the holding element 5 is axially displaceable with the switching gear wheel 4. As shown in FIGS. 3 and 4, in the second position of the switching gear wheel 4, the holding element 5 engages with the first drive gear wheel 2 for holding the first drive gear wheel 2 against rotation. In the first position of the switching gear wheel 4, as shown in FIGS. 1 and 2, the holding element 5 is disengaged from the first drive gear wheel 2. In the embodiment shown, the holding element 5 and the switching gear wheel 4 are coupled to a drive arm 10 and are conjointly displaceable by means of a displacement device 11 (shown schematically). Such a displacement device 11 is for example known from US 5617901 or US 7857011 , which are herewith incorporated by reference.

As shown in FIGS. 1 to 4, in the embodiment shown, the second drive gear wheel 3 is in drive connection with the switching gear wheel 4 in the first position and in the second position of the switching gear wheel 4. Hence, after interrupting a drive connection between the switching gear wheel 4 and the first drive gear wheel 2, the main drive motor 6 can be operated to move the second group of elements, for example for removing a broken weft thread.

The blocking device 9 can be activated for blocking a rotation of the second drive gear wheel 3 while the second drive gear wheel 3 is in standstill, i.e. before, during and after a displacement of the switching gear wheel 4 between the first position and the second position.

FIGS. 7 and 8 show in a perspective view the blocking device 9 and a part of the second drive gear wheel 3 of the drive system 1 of FIG. 1 , while the blocking device 9 is activated and while the blocking device 9 is not activated, respectively. FIGS. 9 to 10 show in sectional views the blocking device 9 and the second drive gear wheel 3.

As best seen in FIGS. 7 and 8, the blocking device 9 comprises a lever 14 having a tooth 15 for engaging with teeth 16 of the second drive gear wheel 3. The lever 14 is mounted swivellable about a swivel axis 17 of the lever 14, which swivel axis 17 is extending in parallel to the rotation axis 18 (see FIGS: 1 to 4) of the second drive gear wheel 3 between a blocking position shown in FIGS. 2, 3, and 7, in which the tooth 15 engages with the second drive gear wheel 3, and a rest position shown in FIGS. 1 , 4, and 8, in which the tooth 15 is disengaged from the second drive gear wheel 3. FIG. 12 shows the lever 14 in isolation. In the embodiment shown, as best seen in FIGS. 7, 8, and 12, the tooth 15 is provided at a side face 19 of the lever 14 facing the teeth 16 of the second drive gear wheel 3. In other words, the tooth 15 is arranged for engaging with a tooth cavity between two teeth 16 of the second drive gear wheel 3.

In the embodiment shown in FIGS. 1 to 11 , the blocking device 9 further comprises an axially displaceable piston 20 extending in parallel to the swivel axis 17 of the lever 14.

The piston 20, in the embodiment shown in FIG. 11 , forms part of a hydraulic actuator 23.

As shown in FIGS. 9 to 11 , a first end 21 of the piston 20 is mounted in the blocking device housing 12 and a second end 22 of the piston 20 is mounted in a frame part 13 of the weaving machine, wherein the first end 21 of the piston 20 is moveably mounted in a first fluid chamber 24 provided in the blocking device housing 12, which can be filled with a hydraulic fluid for moving the piston 20 away from the blocking device housing 12, and the second end 22 of the piston 20 is moveably mounted in a second fluid chamber 25 provided in the frame part 13, which can be filled with the hydraulic fluid for moving the piston 20 away from the frame part 13. As best seen in FIG. 11 , a supply duct 26 for the hydraulic fluid, in particular oil, is formed in the blocking device housing 12, which leads to a valve 27. The valve 27 is selectively operable to supply the hydraulic fluid via a first fluid duct 28 to the first fluid chamber 24, or via a second fluid duct 29, an intermediate annular ring 42 in the blocking device housing 12, a radial duct 43, and an axial duct 44 in the piston 20 to the second fluid chamber 25. In the embodiment shown, at the second fluid chamber 25 a drain duct 30 is provided, which is closed by a drain screw 31 (see FIGS. 7 to 10).

The piston 20 cooperates with the lever 14 so that by an axial displacement of the piston 20 the lever 14 is swivellable between the blocking position shown in FIGS. 2, 3, 7 and 10 and the rest position shown in FIGS. 1 , 4, 8 and 9.

For this purpose, in the embodiment shown, the lever 14 is provided with a passage aperture 32 offset from the swivel axis 17 of the lever 14. As best seen in FIG. 12, in the embodiment shown, a fork-shaped lever 14 having two prongs 33 is provided, wherein the passage aperture 32 is formed between the two prongs 33 and has an open side.

The piston 20 extends through the passage aperture 32 of the lever 14. The passage aperture 32 has two slanting surfaces 34 (see FIG. 12) and the piston 20 has two slanting surfaces 35 (see FIG. 11). The slanting surfaces 34, 35 can cooperate with each other, so that an axial displacement of the piston 20 causes the lever 14 to swivel about the swivel axis 17 of the lever 14, which extends in parallel to the piston 20. Hence, the movement of the piston 20 causes the tooth 15 at the lever 14 to engage or disengage with the second drive gear wheel 3.

As shown in FIGS. 7 to 10, the blocking device 9 further comprises a sensor system 36 for sensing whether or not the blocking device 9 is activated. In the embodiment shown, the sensor system 36 is a proximity sensor system, for example an optical proximity sensor system or an inductive sensor system, comprising a detector 37 and a target 38. The target 38 can be mounted to an opening 39 (see FIG. 12) in the lever 14. In the embodiment shown, the target 38 is a shaft screwed in the opening 39.

The detector 37 is arranged stationary in the blocking device housing 12, in a position so that the target 38 can be detected when the blocking device 9 is activated and the lever 14 is in the blocking position as shown in FIGS. 7 and 10. As shown in FIGS. 8 and 9, when the lever 14 is in the rest position, the target 38 is moved out of a range of the detector 37.

An output of the sensor system 36 can be displayed on a monitor (not shown) of the weaving machine and/or transmitted to a control system (not shown) of the weaving machine.

In use, for example, the brake system 8 and the main drive motor 6 are activated for stopping the weaving machine for a pick finding. After the drive system 1 is moved into a pick finding position, the blocking device 9 can be activated to engage with the second drive gear wheel 3 as shown in FIG. 2. Then the activation of the main drive motor 6 for holding the switching gear wheel 4 in position can be reduced, wherein the blocking device 9 blocks the second drive gear wheel 3. Next, the displacement device 11 can be activated for moving the switching gear wheel 4 into the second position shown in FIG. 3, in which the switching gear wheel 4 is no longer in drive connection with the first drive gear wheel 2, and the holding element 5 engages with the first drive gear wheel 2. Next, the activation of the main drive motor 6 for holding the switching gear wheel 4 in position is enhanced, so that the blocking device 9 can be deactivated to release the second drive gear wheel 3 as shown in FIG. 4, and the main drive motor 6 can be driven in slow-motion to move the second drive gear wheel 3 and the second group of elements including the shed formation device coupled thereto for pick finding to another position, for example a position allowing to remove a weft thread. Then the drive system 1 is moved again to the pick finding position and the blocking device 9 again engages with the second drive gear wheel 3, whereafter the activation of the main drive motor 6 is reduced again. The displacement device 11 can be activated for moving the switching gear wheel 4 into the first position shown in FIG. 2, whereafter the activation of the main drive motor 6 can be enhanced and thereafter the blocking device 9 can be deactivated to release the second drive gear wheel 3 as shown in FIG. 1. Then a normal weaving operation can start.

The invention can be used most advantageous when the shed formation device is a known jacquard system, because during pick finding the forces that are exerted on the second drive gear wheel 3 by the shed formation device are the largest when using a jacquard system.

In the embodiment shown, a teeth area of the first drive gear wheel 2 is provided with two notches

45 (see FIG. 1) running over part of the axial length of the first drive gear wheel 2 and several teeth. Therefore, interrupting the drive connection between the switching gear wheel 4 and the first drive gear wheel 2 is only possible in two defined angular positions of the first drive gear wheel 2. The notches 45 can be provided as known from US 5617901 , which is herewith incorporated by reference.

FIG. 13 shows a second embodiment of a blocking device 9 in an activated state. The blocking device 9 shown in FIG. 13 comprises a lever 14 with a tooth 15 for engaging with teeth 16 of the second drive gear wheel 3 (see FIGS. 1 to 10). The lever 14 shown in FIG. 13 is also mounted swivellable about a swivel axis 17 and swivellable between a blocking position shown in FIG. 13, in which the tooth 15 can engage with the second drive gear wheel 3, and a rest position (not shown), in which the tooth 15 is disengaged from the second drive gear wheel 3. In the embodiment shown in FIG. 13, the blocking device 9 comprises an excentre 46 for moving the lever 14, which excentre 46 can be swiveled back-and-forth or rotated about an axis of rotation 47 that is parallel to the swivel axis 17 of the lever 14. In the embodiment shown, the excentre 46 is driven using a piston 48 that is mounted transversely to the axis of rotation 47 of the excentre

46 and connected to the excentre 46 via a connecting rod 49. The piston 48 can be driven by a cylinder 50, for example a hydraulic or pneumatic cylinder, that is rotatable around a fixedly arranged axis of rotation 51 .

In the embodiments shown in FIGS. 1 to 4, the gear wheels 2, 3, 4 and 7 are spur gears or straight-cut gears, wherein all rotation axes of the gear wheels are arranged in parallel, and wherein by movement of the switching gear wheel 4 in parallel to the rotation axis 53 of the first drive gear wheel 2, the switching gear wheel 4 and the first drive gear wheel 2 can engage or disengage. In an alternative embodiment (not shown), the gear wheels 2, 3, 4 and 7 are helical gear wheels, wherein for engaging or disengaging the switching gear wheel 4 and the first drive gear wheel 2 a movement of the switching gear wheel 4 in parallel to the rotation axis 53 of the first drive gear wheel 2 is combined with a controlled rotation of the switching gear wheel 4, while for example the second drive gear wheel 3 is blocked by the blocking device 9. When the second drive gearwheel 3 is a helical gear wheel, the tooth 15 can be arranged at an angle with respect to the swivel axis 17 of the lever 14, so that the tooth 15 can engage between two teeth 16 of the second drive gear wheel 3 for blocking the second drive gear wheel 3. Also, the holding element 5 is profiled to cooperate with the helical gears.