NOZZLE DEVICE

Abstract: A nozzle device preferably for jet weaving machine, comprises a supply (20), an outlet nozzle (11, 25, 15, 32), a conduit (17) connecting the supply (20) and the outlet nozzle (11, 25, 15; 32) and a valve unit (24). For enhancing the dynamic behaviour of the nozzle device, the valve unit comprises a displaceable, soft-magnetic valve body (24) and a coil (3) for generating a magnetic field extending through the valve body, wherein the valve body is arranged within the conduit (17) such that the flowing of pressurized medium therethrough exerts a force on the valve body (24) which is opposite to the force as generated by the magnetic field. (Fig. 1)

Description: The present invention relates to a nozzle device, preferably for inserting of a weft yarn through the shed of a weaving machine by means of a jet of pressurized medium in accordance with the prior art portion of claim 1. In jet weaving machines the weft yarn is inserted through the shed by means of a pulse-like jet of air, and/or fluid. The necessary jet of pressurized medium is generated by a nozzle device, which in conventional jet weaving machines comprises a nozzle mounted on a sley in the weaving machine which is supplied by a pressure medium from a valve device positioned stationarily in the weaving machine, which is controlled by a electric control unit operating the valve device in synchronism with the operation of the weaving machine. In addition to a so-called main nozzle, which is arranged at the insertion side of the weft yarn in the weaving machine outside the shed, so-called relay-nozzles are arranged on the sley in the shed at equal distances from one another, which relay nozzles are also connected to valve devices which are stationarily arranged in the weaving machine and controlled by the electric control unit thereof. The electric control unit of the weaving machine successively operates the main nozzle and the respective relay nozzles during each pick or weft yarn shot for bringing the weft yarn to the arrival end in the shed. The volume of pressurized medium contained in the ducts between the respective valves and the respective nozzles of these conventional nozzle devices having separate valves and nozzles results in considerable response times which in turn negatively affect the control behaviour of the overall system. Another type of nozzle device having an integrated valve which is known from US-A-4 466 468. This prior art nozzle device comprises a supply for pressurized medium, an outlet nozzle in the form of a passageway through which the weft yarn is guided, a conduit connecting the supply and the outlet nozzle and a valve unit arranged between the supply and the outlet nozzle. The conduit includes an outer storage chamber which, in the open position of the valve unit, is in connection with a cone-shaped duct terminating at the nozzle passageway. The cone-shaped duct and the outer chamber are separated by a rounded edge which is in contact with a flexible diaphragm extending in the radial direction of the device which diaphragm and edge together form the valve unit. The position of the diaphragm is controlled by the pressure of a control air which is fed to the prior art nozzle device by separate solenoids or rotary spool valves. When reducing the pressure of the control air the diaphragm is bent away from the rounded edge so that the pressurized medium flows from the storage chamber to the outlet nozzle. The dynamic control behaviour of this prior art nozzle device is subject to inherent limitations caused by the two-stage valve design necessitating a servo-valve for controlling the operation of the main valve in the form of the diaphragm. In other words, the overall response time of this prior art nozzle device is necessarily longer than the sum of the response times of the servo-valve unit and of the nozzle device itself. Moreover, this prior art nozzle device has a complicated mechanical design caused by the necessity of a diaphragm and a conduit in the form of an outer storage chamber and a cone-shaped duct terminating at the outlet nozzle. In view of the above prior art nozzle devices, the present invention is based on the object of achieving a nozzle device having a favourable dynamic behaviour although having a relatively simple design. This object is achieved by a nozzle device in accordance with the prior art portion of claim 1 having the characterizing features thereof. In accordance with the present invention, the valve unit comprises a displaceable soft-magnetic valve body and a coil for generating a magnetic field extending through the soft-magnetic valve body when feeding an actuation current to the coil. The displaceable, soft-magnetic valve body is arranged within the conduit such that the flowing of pressurized medium through the conduit from the supply to the outlet nozzle exerts a force on the valve body having an opposite direction when compared to the direction of the force as generated by the magnetic field. In a preferred embodiment the magnetic field generated by the coil when feeding the actuation current thereto moves the soft-magnetic valve body in its open position allowing a flowing of the pressurized medium from the supply through the conduit to the outlet nozzle. When terminating the actuation current, the pressurized medium flowing along the valve body urges it in its closed position due to frictional forces between the flowing pressurized medium and the valve body itself. When changing the flow direction of the pressurized medium with regard to the direction of movement of the valve body from its open to its closed position, the flowing of pressurized medium can also be used for opening the valve body while closing it due to the magnetic field as generated by the coil when feeding an actuation current thereto. As claimed in claim 2, the valve body preferably has an annular shape, wherein the inner surface of the valve body is in sealing, sliding contact with respect to a cylindric inner wall of the conduit. Although an annular design of the valve body and a cylindric form of the inner wall are preferable for constructional reasons, other cross-sections of the valve body and of the inner wall may also be chosen. In accordance with claim 3, the conduit has an annular portion and surrounds the cylindric, inner wall and the valve body and comprises a radially inwardly extending portion interconnecting the annular portion and the outlet nozzle. Furthermore, the valve body is displaceable in its axial direction for sealing against an essentially radial abutment portion so as to interrupt the radially inwardly extending portion of the conduit. This particular advantage caused by this particular design of the conduit permits a guiding of the pressurized medium along the outer surface of the valve body parallel to its direction of movement in its closed position while it renders possible to manufacture the parts of the nozzle body by machining them. In accordance with claim 4, the valve body has radially extending grooves at its outer surface. These radial grooves increase the friction between the pressurized medium flowing along the outer surface of the valve body and the valve body itself. Hence, the force urging the valve body in its closed position is desirably increased for shortening the closing time of the valve upon terminating the actuation current fed to the coil of the nozzle device. In accordance with claim 5, the valve body has radial bores defining a residual flow of pressurized medium in the closed position of the valve body. The residual flow keeps the resting weft yarn under control. In accordance with claim 5, the valve body consists of an annular portion of soft-magnetic material and a shoe made of elastomeric material. The shoe of elastomeric material forms a sealing surface between the valve body itself and the radial abutment portion. Hereinafter, preferred embodiments of the nozzle device in accordance with the present invention will be described with reference to the attached drawings, in which: Fig. 1 shows a cross-sectional representation of a first embodiment of the nozzle device in accordance with the present invention wherein a valve unit is in its closed position; Fig. 2 is a cross-sectional representation of the embodiment in accordance with Fig. 1, wherein the valve unit is in its open position; and Fig. 3 shows a cross-sectional representation of a second embodiment of the nozzle device in accordance with the present invention. As shown in Fig. 1, a nozzle device 1 in the form of a so-called main nozzle comprises a housing 2 which can be fixedly mounted to a sley in a weaving machine (not shown here). An electro-magnetic coil 3 is located within the housing 2 and is kept in its axial positon by means of an annular mounting body 4 which is inserted in the housing 2 under press fit. The inner surface of the mounting body 4 has partially the form of an inner thread 5 engaging an outer thread 7 of an abutment portion 6. The abutment portion 6 has a central yarn passage 8 for guiding the yarn 9 through the main nozzle device. The abutment portion 6 is screwed into the mounting body 4. A yarn guiding eyelet 10 consisting of ceramic material is attached to the outer central orifice of the abutment portion 6. The abutment portion 6 has an axial extention at its inner central orifice in the form of a short tube 11 having thin walls. At the left-hand side of the main nozzle device 1 in accordance with Fig. 1, the housing 2 is equipped with an inner thread 11. A longitudinal passageway body 13 essentially consisting of a tube-like member is equipped with an outer thread 14 by means of which the longitudinal passageway body 13 is screwed into the inner thread 12 of the housing 2 in a position which is adjustable relative to the abutment portion 6. The tube-like member 15 forms a long tube extension 16 at the left-hand side of the longitudinal passageway body 13 in accordance with Fig. 1. The inner diameter of an inner portion of the housing 2, the coil 3 and the mounting body 4 is slightly greater than the outer diameter of the tube-like member 15 of the longitudinal passageway 13 so that an annular-shaped conduit 17 is defined between these parts. Compressed air is supplied to the annular-shaped conduit 17 through a plurality of radial holes 18 which are connected to an outer annular recess 19 formed by an annular groove provided in the outer surface of the housing 2. A supply of compressed air formed by an air compressor (not shown in the drawings) is in connection with the annular recess 19 by means of a pressure air connection member 20. The pressure air connecton member has an inner bore 21 corresponding to the outer diameter of the housing 2 in the range of the connection member 20. A pressure-tight sealing between the connection member 20 and the outer surface of the housing 2 is created by three 0-rings 21, 22 and 23. An annular-shaped valve body 24 consisting of a soft-magnetic material is in sealing, sliding contact with a cylindric inner wall portion 25 of the conduit 17, which cylindric inner wall portion 25 is formed by a right-hand extension of the tube-like member 15 of the longitudinal passageway body 13. The valve body 24 is displaceable along the axial direction of the tube-like member 15. In a first position of the valve body 24 which corresponds to the open position of the valve it rests against the longitudinal passageway body 13 in this position of the valve body 24 the compressed air flows from the connection member 20 via the annular-shaped conduit 17 through a radially inwardly extending portion of the conduit 26 (see Fig. 2) in a conduit portion defined by the inner wall of the cylindric inner wall portion 25 of the tube-like member 15 and the outer wall of the tube 11 of the abutment portion 6 into the yarn passage 8 of the nozzle device 1. The valve body 24 is in this first position when the electro-magnetic coil 3 is supplied with an actuation current generated by an electric control unit (not shown here) working in synchronism with the weaving machine. The valve body 24 is in its first position when the weft yarn insertion is carried out. When moving the valve body from its closed position in its first open position, the yarn being at rest in the previous moment, will be quickly accelerated by the compressed air blowing the weft yarn through the shed of the weaving machine. In the other working position of the valve body 24 which is shown in Fig. 1, the valve body 24 rests against the abutment portion 6. The valve body 24 has some fine radial bores 27 having a diameter in the range of 0.3 mm. These fine radial bores define a residual flow of pressurized medium in the closed position of the valve body 24 for keeping the resting yarn under control. The valve body 24 is in this second position when no actuation current is fed to the electro-magnetic coil 3. In other words, the soft-magnetic valve body 24 is kept in its open, first position by the magnetic force exerted upon it by the magnetic field generated by the coil 3 when feeding an actuation current thereto. When switching-off the actuation current, the flowing of the pressurized medium along the outer surface of the valve body 24 causes frictional forces shifting the valve body 24 in its closed position. For shortening the closing operation the valve body 24 is equipped with radially extending grooves 28. The valve body is equipped with a shoe 29 consisting of elastomeric material which is located at the end of the valve body 24 facing the abutment portion 6. This shoe enhances the sealing of the valve body 24 with regard to the abutment portion 6. Preferrably, the valve body 24, the housing 2, the mounting bodies 3 and the longitudinal passageway body 13 are made of soft-magnetic material whereas the abutment portion 6 consists of non-soft-magnetic material. Fig. 3 shows a second embodiment of a nozzle device in accordance with the present invention which has the form of a relay nozzle 30. The relay nozzle 30 has essentially the same design when compared to the main nozzle device 1 as shown in Figs. 1 and 2. Therefore, only those parts will be described hereinafter which differ in design and function when compared to the parts of the embodiment in accordance with Figs. 1 and 2. The relay nozzle 30 does not have a yarn passage 8 but has instead thereof a tube-shaped part 31 extending from the abutment portion 6. The abutment portion 6 is not equipped with a tube 11 at its inner orifice. The free end of the tube-shaped part 31 is provided with a plurality of fine-holes 32 forming a group of outlet nozzles. In the open position of the valve body 24 the pressure medium in the form of pressurized air flows from the fluid supply via the annular-shaped conduit through the essential radially inwardly extending portion 26 of the conduit through the tube-shaped part 31 to the fine holes 32. The air jet generated at the fine holes 32 supports the feeding of the yarn 9 through the shed 33 of the weaving machine and thus carries the yarn 9 to the arrival end of the shed. The interior of the longitudinal body 30 is filled by a filler-member 34 consisting of a non-soft-magnetic material. The nozzle device in accordance with the present invention renders it possible to minimize the "dead" volume of air or medium between the nozzle and the valve when compared to prior art devices having separate, non-integrated valves. When compared to the prior art nozzle device having an integrated valve the present invention not only teaches a simplified design of the nozzle device, but also how to achieve a shortened response time thereof by avoiding servo-valves controlling the main valve. The valve body 24 can have a very short stroke length in the range of 0.3 - 0.4 mm resulting in a further shortening of the nozzle response time. The valve body is brought in its non-actuated position by the flow of pressurized medium which further contributes to the simplicity of the design and to the shortening of the response time of the device. The short response time of the nozzle device in accordance with the present invention enhances the control behaviour of the weft yarn insertion procedure and avoids an over-stretching of the yarn at the beginning and at the end of a pick. The elimination of the "dead" volume and the reduction of the response time permits a saving of consumed pressurized medium. When utilizing the nozzle device in accordance with the present invention in a multi-colour weaving machine only one hose for compressed air is required for the supply for the respective nozzles, which simplifies the overall design of the weaving machine.

Claims: 1. Nozzle device (1): preferably for inserting of a weft yarn (9) through the shed (33) of a weaving machine by means of a jet of pressurized medium, comprising: a supply (20) for said pressurized medium, an outlet nozzle (11, 25, 15; 32), a conduit (17) connecting said supply (20) and said outlet nozzle (11, 25, 15; 32), and a valve unit (24) arranged between said supply (20) and said outlet nozzle (11, 25, 15, 32), characterized in that said valve unit comprises a displaceable, soft-magnetic valve body (24) and a coil (3) for generating a magnetic field extending through said soft-magnetic valve body (24) when feeding an actuation current to said coil (3) and that said displaceable, soft-magnetic valve body (24) is arranged within said conduit (17) such that the flowing of pressurized medium through the conduit (17) from the supply (20) to the outlet nozzle (11, 25, 15; 32) exerts a force on said valve body (24) which is opposite to the force as generated by said magnetic field. 2. Nozzle device as claimed in claim 1 characterized in that said valve body (24) has an annular-shape and that the inner surface of said valve body (24) is in sealing, sliding contact with a cylindric inner wall (25) limiting said conduit (17). 3. Nozzle device as claimed in claim 2, characterized in that said conduit has an annular portion (17) and surrounds said cylindric, inner wall (25) and said valve body (24), and a radially inwardly extending portion (26) interconnecting said annular portion (17) and said outlet nozzle (11, 25, 15; 32), and that said valve body (24) is displaceable in its axial direction for sealing against an essentially radial abutment portion (6) so as to interrupt said radially inwardly extending portion (26) of said conduit (17, 26). 4. Nozzle device as claimed in one of the claims 1-3, characterized in that said valve body (24) has radially extending grooves (28) at its outer surface. 5. Nozzle device as claimed in one of the claims 1-4, characterized in that said valve body (24) has radial bores (27) defining a residual flow of pressurized medium in the closed position of the valve body (24). 6. Nozzle device as claimed in one of the claims 1-5, characterized in that said valve body (24) consists of an annular portion of soft-magnetic material and of a shoe (29) of elastomeric material.

Inventors: THOLANDER, LARS HELGE GOTTFRID
Applicants: IRO AB
Application year: 1987
Main classification: D03D47
IPC codes: D03D47