Abstract:
A loom having a subassembly including heddles, a beater, and a device for inserting weft into a shed formed by warp yarns and also including a shed-forming device and a lubrication system for lubricating certain components of the subassembly including a first circuit for circulating a first lubricant and a second circuit for circulating a second lubricant for lubricating the shed forming device. The loom includes a heat exchanger system for exchanging heat between the first lubricant and the second lubricant without fluid communication between the lubricants.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a loom in which use is made of a lubricant, such as oil, in particular within a shed-forming device of the dobby, cam mechanism, or Jacquard mechanism type. 
     2. Brief Description of the Related Art 
     Modern looms operate at high speeds, often faster than 900 picks per minute. The shed-forming devices associated with such looms need to develop a large amount of mechanical power, some of which is lost to friction, thereby producing heat. This heat production increases the temperature of the oil used within such a device for lubricating its moving parts. The oil heats up to a temperature such that a cover of such a shed-forming device can become too hot to touch, which is dangerous for an operator nearby. This heating also has the consequence of the oil reaching a temperature range in which its viscosity is significantly modified, to such an extent that it is no longer guaranteed that a film of oil between two contacting parts will have the necessary thickness. 
     It is known from JP-A-10 251943 to feed with oil several components of a loom, from a single tank. A water circuit is used to cool the content of this tank. 
     US-A-2003/0178089 discloses circulating the oil of a shed-forming device through an external plate heat exchanger of the water/oil type. That approach requires the use of a cold source external to the loom and requires water to be brought to the heat exchanger, thereby requiring pipes to be installed over a considerable length. Furthermore, that approach imposes mixing the oil used for lubricating the various portions of a loom in order to take the oil to the heat exchanger. Unfortunately, the oil that is best suited to lubricating the shed-forming device is not necessarily the same as the oil that is best suited to lubricating a beater box or means for controlling of a device for inserting picks in a loom. It is therefore necessary to accept a compromise concerning the type of oil that is to be used. Furthermore, in spite of settling devices being used, hard particles produced in the event of failure of one of the members of the loom or of the shed-forming device may then contaminate all of the other members and may significantly shorten the lifetime of the loom. 
     SUMMARY OF THE INVENTION 
     The invention seeks more particularly to remedy those drawbacks by proposing a novel loom that includes, amongst others, a shed-forming device that is lubricated under good conditions without spoiling the nature of the lubricant used to do this. 
     To this end, the invention provides a loom comprising: a subassembly including heddles, a beater, and means for inserting weft into the shed formed by warp yarns, and a shed-forming device. In this loom, lubrication means for lubricating certain components of the above-mentioned subassembly include a first circuit for circulating a first lubricant, and means for lubricating the shed-forming device and including a second circuit for circulating a second lubricant. In accordance with the invention, the loom includes a heat exchanger system for exchanging heat between the first lubricant and the second lubricant without fluid communication between these lubricants, and the heat exchanger system comprises means for circulating one of the lubricants selected from the first and second lubricants, or a coolant fluid to a zone where the lubricant or the coolant fluid is in thermal contact with another lubricant selected from the first and second lubricants. 
     By means of the invention, one of the lubricants, having an operating temperature that rises relatively little, is used to cool the other lubricant that has an operating temperature that rises further. In practice, the invention makes it possible to use the first lubricant that circulates through the components of the subassembly including, amongst others, the heddles, the beater, and the weft inserter means, in order to cool the second lubricant that flows through the shed-forming device. The temperature of the first lubricant is generally less than 70° C., since this lubricant comes into contact with relatively large heat exchange areas with air, whereas the temperature of the lubricant in the shed-forming device is higher because that equipment is compact. 
     According to aspects of the invention that are advantageous but not essential, a loom in accordance with the invention may incorporate one or more of the following features taken in any technically feasible combination:
         The means for putting the lubricant into circulation comprise at least one pump and associated lines for circulating one of the lubricants selected from the first lubricant and the second lubricant or the coolant fluid to the thermal contact zone or from said zone.   The loom includes at least one temperature sensor for sensing the temperature of one of the lubricants or of a coolant fluid.   The loom includes regulation means for regulating heat exchange between the first and second lubricants. The regulation means advantageously comprise means for controlling the pump as a function of the signal output by the temperature sensor.   The heat exchanger means comprise a heat exchanger and means for bringing the first and second lubricants to the heat exchanger.   The heat exchanger means comprise a third circuit in which a coolant fluid circulates between a first zone of thermal contact with the first circuit and a second zone of thermal contact with the second circuit.   At least one of the coolant fluid circulation circuits includes a volume forming a supply of lubricant circulating in said circuit, and the heat exchanger means include means for bringing a coolant fluid or the lubricant of the other circuit into the supply-forming volume.   The first lubricant is used for lubricating means for driving the beater, the weft inserter means, and/or a device for driving a beam or a roller for winding the cloth.       

     The invention also provides a method of controlling the temperature of a lubricant in a shed-forming device suitable for use in a loom, as mentioned above. The method consists in putting said lubricant into thermal contact with another lubricant used for lubricating certain components of a subassembly of the loom, which subassembly includes heddles, a beater, and means for inserting weft into the shed formed by warp yarns. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be better understood and other advantages thereof appear more clearly in the light of the following description of five embodiments of looms in accordance with its principle, given purely as examples and with reference to the accompanying drawings, in which: 
         FIG. 1  is a diagram showing the principle of a loom in accordance with a first embodiment of the invention; and 
         FIGS. 2 to 5  are diagrams analogous to  FIG. 1  showing looms respectively in accordance with second, third, fourth, and fifth embodiments of the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The loom  1  shown in  FIG. 1  includes a subassembly  2  within which warp yarns and weft yarns (not shown) are woven. The subassembly  2  has a plurality of heddle frames  21 , each fitted with a plurality of heddles  212 , only some of which are shown in  FIG. 1  for clarity in the drawing, each of which is provided with an eyelet  214  for passing a warp yarn. These heddle frames  21  are driven by pull rods  22 , themselves controlled by reversing levers (not shown). 
     The subassembly  2  also includes a beater or comb  23  for striking the weft yarns after weaving in order to make the cloth compact. The beater is hinged about an axis Y 23  perpendicular to the direction in which the heddle frame  21  oscillates vertically, as represented by double-headed arrow F 1 . A drive mechanism  24  moves the beater  23  to pivot back and forth about the axis Y 23 . 
     The subassembly  2  also has weft inserter means  25  and  26  disposed on either side of the frames  21 . These means  25  and  26  serve to control rapiers  252  and  262  that are used for inserting weft yarns into the shed formed by the warp yarns that pass through the eyelets  214 . 
     The subassembly  2  also includes a beam from which the warp yarns are unwound on their way towards the eyelets  214  of the heddles  212 , together with a roller onto which the cloth is wound progressively while it is being fabricated on the loom  1 . The beam and the roller are not shown in  FIG. 1 . They are driven by respective mechanisms  28  and  29  provided for that purpose. 
     A circuit C 1  for circulating a first oil is provided inside the subassembly  2  in order to lubricate the mechanism  24 , the weft inserter means  25  and  26 , and the mechanisms  28  or  29 . In a variant, the circuit C 1  may be used to lubricate only some of the pieces of equipment mentioned above, or other pieces of equipment forming part of the subassembly  2 . 
     In  FIG. 1 , the circuit C 1  is represented very diagrammatically by means of arrows that do not necessarily correspond to the path followed by the circuit C 1  in the subassembly  2 . 
     The circuit C 1  includes a pan  31  formed in the bottom portion of a casing  30  of the subassembly  2 . A pump  32  is installed in the pan  31  and serves to circulate the oil via ducts (not shown in detail) within the circuit C 1 , each leading to mechanisms for lubricating. The oil of the circuit C 1  also has a thermal function insofar as it serves to cool the parts of the subassembly  2  with which it comes into contact. This first oil thus performs a lubricating function and a cooling function, such as that provided by a coolant fluid. 
     The loom  1  also has a dobby  4  for driving the various heddle frames  21 . To do this, the dobby  4  has as many oscillating levers  42  as there are pull rods  22  in the set, each lever  42  being dynamically connected to the rods  22  of a heddle frame  21  in known manner that is represented by a chain-dotted line  44  in  FIG. 1 . 
     A second lubrication circuit C 2  is provided inside the dobby  4 . This circuit has a pan  51  formed in the bottom portion of a casing  50  of the dobby  4  and within which there is placed a pump  52  serving to circulate a second oil via ducts (not shown) within the circuit C 2  and leading to portions of the dobby  4  that need to be lubricated. 
     The circuit C 2  is also shown in highly diagrammatic manner. The oil of the circuit C 2  also has a thermal function, insofar as it serves to cool those parts of the dobby  4  with which it comes into contact. This second oil thus performs both a lubricating function and a cooling function, like that of a coolant fluid. 
     Given its compact nature and its speed of operation, the dobby  4  tends to heat up strongly, such that the second oil flowing in the circuit C 2  and present in the pan  51  reaches a high temperature, a temperature higher than that of the first oil. 
     In order to limit the heating of the oil present in the dobby  4 , a heat exchanger system  6  is provided to enable the oil present in the circuit C 2  to be cooled by means of the oil present in the circuit C 1 . In operation of the loom  1 , the oil of the circuit C 1  heats up less than the oil of the circuit C 2  because the heat exchange areas of the circuit C 1  with the outside are larger. In practice, in a high-performance loom, the temperature of the oil in the circuit C 1  is of the order of 50° C. to 70° C., whereas the temperature of the oil in the circuit C 2  is of the order of 80° C. to 100° C., or even more. For this purpose, a heat exchanger  62  is installed between the subassembly  2  and the dobby  4 . 
     The heat exchanger  62  is fed from the pan  31  by a line  631  having a pump  641  installed therein. A return line  651  returns oil from the heat exchanger  62  to the pan  31  of the circuit C 1 . 
     Furthermore, a feed line  632  connects the pan  51  to the heat exchanger  62 . A pump  642  is installed in this feed line, and a return line  652  connects the heat exchanger  62  to the pan  51 . 
     Thus, the pumps  641  and  642  serve to convey respective quantities of oil to the heat exchanger  62 . Insofar as the oil present in the pan  31  is at a temperature that is lower than the temperature of the oil present in the pan  51 , this serves to lower the temperature of the oil in the circuit C 2 . 
     A temperature probe  711  is placed at the inlet to the heat exchanger  62  on the line  631 , and a temperature probe  721  is placed at the outlet from the heat exchanger  62  on the line  651 . Similarly, two temperature probes  712  and  722  are placed at the inlet and the outlet of the heat exchanger  62 , on the lines  632  and  652  respectively. 
     A valve  731  is installed in the line  631  between the pump  641  and the probe  711 . Similarly, a valve  732  is installed in the line  632 , between the pump  642  and the probe  712 . 
     An electronic control unit  66  controls the operation of the pumps  641  and  642  by means of electric signals S 641  and S 642 . The unit  66  also controls the operation of the vales  731  and  732  by means of dedicated electric signals S 721  and S 722 . The output signals from the temperature probes  711 ,  712 ,  721 , and  722  are delivered respectively to the unit  66  in the form of electric signals S 711 , S 712 , S 721 , and S 722 . 
     By construction, the oil circulation ducts of the subassembly  2  in the lines  631  and  651  and in the heat exchanger  62  are separated in leaktight manner from the oil circulation ducts of the dobby  4  in the lines  632  and  652  and in the heat exchanger  62 . In other words, the exchange of heat between the oil of the subassembly  2  and the oil of the dobby  4  does not give rise to either of these oils becoming polluted with the other. 
     When the loom  1  is put into operation, with the oils then being cold, the valve  732  is controlled by the unit  66  so that the oil flow rate in the line  632  is relatively low. The oil in the circuit C 2  is cooled little and heats up quickly in order to reach a temperature threshold above which its fluidity enables it to penetrate into the smallest clearances and to eliminate any risk of sticking phenomena occurring inside the dobby  4 . 
     Once this threshold temperature has been reached, the flow rate in the line  632  is raised progressively and then stabilized when a second threshold value is reached that is higher than the first threshold value. 
     The flow rate of oil from the circuit C 2  through the heat exchanger  62  may also be controlled by the signal S 642  that serves to control the speed of rotation of the pump  642 . 
     In practice, as mentioned above, the oil of the circuit C 2  reaches a temperature of about 90° C. under steady conditions, whereas the temperature of the oil in the circuit C 1 , in particular the temperature of the oil in the pan  31 , is of the order of 60° C. Because of the heat exchanger system of the invention, the oil temperature in both circuits C 1  and C 2  is about 70° C. 
     By acting on the respective degrees of opening of the valves  731  and  732  or on the speeds of rotation of the pumps  641  and  642 , it is possible to control the respective flow rates of oil in the circuit C 1  and of oil in the circuit C 2  in order to maintain a temperature difference between these oils. Maintaining such a temperature difference is nevertheless not compulsory. 
     The system  6  may operate without regulating the flow rate of oil in the circuit C 1  and of oil in the circuit C 2 . Nevertheless, making use of some or all of the temperature probes  711 ,  712 ,  721 , and  722  makes it possible to detect whenever a threshold value is exceeded that is potentially dangerous for the quality of the oils being used or for the equipment with which the oils come into contact, such as sealing gaskets. In the event of such a threshold value being exceeded, operation of the loom  1  may be stopped by the control unit  66 , or an alarm may be triggered. 
     In the second to fifth embodiments shown in  FIGS. 2 to 5 , elements that are analogous to elements of the first embodiment are given the same references. Below, the description relates only to matters that distinguish each embodiment from the first embodiment. Unless mentioned to the contrary, the structure and the operation of the devices in  FIGS. 2 to 5  are identical to those of the first embodiment. 
     In the second embodiment, no pumps are provided within the heat exchanger system  6  in the lines  631  and  632  feeding the heat exchanger  62  with oil from the circuits C 1  and C 2 . The pumps  32  and  52  of the circuits C 1  and C 2  are used for this purpose insofar as they deliver directly into the feed lines  631  and  632 , with the elements for lubricating being fed from the return lines  651  and  652 . This embodiment is less expensive than the preceding embodiment since it enables the pumps  641  and  642  of the first embodiment to be omitted. 
     In the third embodiment, a coolant fluid circuit C 3  is installed between the pan  31  of the subassembly  2  and the pan  51  of the dobby  4 . A heat exchange zone Z 1  is provided between the circuit C 3  and the content of the pan  31 , within said pan, and a second heat exchange zone Z 2  is provided between the circuit C 3  and the content of the pan  51 , within said pan. These heat exchange zones are made within the heat exchanger system  6  by means of coils  671  and  672  through which the coolant fluid flows, which coils are placed within the pans  31  and  51 . The heat exchange zones Z 1  and Z 2  are leaktight. 
     The coolant fluid of the circuit C 3  may be of any known type and need not necessarily be an oil, since it does not perform any lubrication function. 
     A pump  643  is installed in one of the pipes  633  of the circuit C 3  connecting the zone Z 1  to the zone Z 2 . This pump serves to cause the coolant fluid to circulate between the zone Z 2  and Z 1  and to return via a pipe  653 . 
     A valve  733  serves to regulate the flow rate of coolant fluid in this circuit, and consequently to regulate the magnitude of the heat exchange between the oils belonging respectively to the circuit C 1  and to the circuit C 2 . The valve  733  is controlled by an electronic control unit  66  via an electric signal S 733 . 
     In a variant, the pump  643  may be controlled by the unit  66 , as in the first embodiment. 
     In this embodiment, heat exchange between the oils of the circuits C 1  and C 2  is indirect, passing via the coolant fluid C 3 . 
     This embodiment is particularly suitable for shed-forming devices and for loom subassemblies in which no pump is provided that is equivalent to the pumps  32  and  52  of the first and second embodiments. 
     In the fourth embodiment, a portion of the content of the pan  31  is pumped into a circuit C 4  that includes a leaktight heat exchange zone Z 4  constituted by a coil  674  placed in the pan  51  of the dobby  4 . A pump  644  serves to circulate the oil of the circuit C 1  through the circuit C 4  that comprises a line  634  for feeding the coil  674  and a return line  654  going back to the pan  31 . Under such circumstances, the relatively cold oil of the circuit C 1  is taken to the pan  51  of the circuit C 2  in order to cool the oil located therein. 
     In the fifth embodiment, an approach is adopted that is the inverse of that of the embodiment of  FIG. 4 . In other words, the oil of the circuit C 2  is taken to the pan of the circuit C 1  within a leaktight heat exchange zone Z 5  formed by a coil  675  forming part of a circuit C 5  within which a pump  645  is located. Oil taken from the pan  51  flows along a line  635  for feeding the coil  675  and returns to the pan  51  via a return line  655 . 
     In the embodiments of  FIGS. 4 and 5 , valves  734  and  735  controlled by signals S 734  and S 735  delivered by an electronic control unit  66  serve to regulate the flow of oil in the circuits C 4  and C 5  and through the heat exchanger systems  6 . The valves  734  and  735  may include branch connections leading to the lines  654  and  655 . 
     In the embodiments of  FIGS. 2 to 5 , temperature sensors  711 ,  712 ,  721 , and/or  722  are used, as in the first embodiment. Nevertheless, this is not compulsory. 
     Whatever the embodiment, heat exchange between the oil of the circuit C 1  and the oil of the circuit C 2  enables the temperature of the oil of the shed-forming device to be lowered, and this is advantageous in terms of the lubrication and in terms of the lifetime of this equipment. Insofar as the two circuits C 1  and C 2  remain separated from each other, given that the heat exchanger zone is leaktight, it is possible to use different oils in these two circuits. 
     The invention is described above for a shed-forming device constituted by a dobby. The dobby may be of the positive type or of the negative type. It is also possible for the shed-forming device to be a basic weave mechanism or a Jacquard machine if the loom is a Jacquard loom. 
     The loom may be a single-layer loom or a two-layer loom and it may be used for weaving any type of cloth. 
     The invention applies to looms having rapiers as shown in the figures, and also to looms using projectiles, air, or water. 
     In the embodiments described and shown in the figures there are pumps for circulating oil in the circuits C 1  and C 2 . Nevertheless, the invention can be used with oil-bath circuits in which it is the movement of the parts in the subassembly  2  and/or in the shed-forming device  4  that suffices to lubricate the joints by spraying. 
     Under such circumstances, the circuits C 1  and/or C 2  are formed by zones in which oil circulates in the equipment  2  and/or  4 . 
     The technical characteristics of the embodiments and variants described above may be combined with one another.