Patent Document

This application claims priority based on an International Application filed under the Patent Cooperation Treaty, PCT/EP2007/008170, filed Sep. 20, 2007. 
     BACKGROUND OF THE INVENTION 
     The invention relates to an electrical direct linear drive device. 
     In connection with such a direct linear drive device known from DE 298 07 438 U1, two guide rails are arranged on one side of the stator in an essentially identical plane. One of the guide rails is used only as a support for compensating tolerances and heat expansions, and the associated guide element of the carriage can be freely displaced transversely to the linear guidance direction. Although the heat expansion of the carriage, which becomes heated when operated, no longer plays a substantial role because of this, such an arrangement is only suitable for the horizontal seating of the carriage on the guide rails. No sufficient guidance of the carriage is assured in all other positions of the linear drive device. 
     SUMMARY OF THE INVENTION 
     One object of the present invention lies in providing a guide device with two rails, which is independent to a large extent of the spatial position of the direct linear drive device, but with which tolerances and heat expansions can be controlled to a sufficient degree. 
     In accordance with the invention, this object is attained by means of a direct linear drive device with a stator having two guide rails for the linear guidance of a driven carriage, wherein a permanent magnet arrangement providing the electrical drive and a drive coil arrangement, which is movable relatively thereto, are provided, and wherein the guide rails are arranged on sides of the stator which are differently oriented, and wherein the carriage extends at least partially over each one of these sides, and wherein guide elements having guide channels for the guide rails are arranged on the carriage. 
     By means of the arrangement of the guide rails, which are essentially arranged offset by 90° in respect to each other, more advantageous conditions regarding tolerances and heat expansion result, in which the direct linear drive device can assume a multitude of spatial positions. The carriage extends at least partially over two sides of the stator, so that by means of the two mounting faces of the carriage constituted by this a variable shaft structure and variably attachments, for example a drag chain or cooling body, can be realized. Moreover, multi-shaft systems are made possible by this arrangement. 
     Advantageous further developments and improvements of the direct linear drive device are possible. 
     In an advantageous manner, the carriage has an essentially L-shaped profile and in particular has two plate-shaped carriage areas arranged at right angles to each other, whose exterior surfaces can be used as mounting faces for the placement of attachments or for the variable fastening of the carriage on a base, where in the second case the stator constitutes the moving element. 
     In one embodiment of the invention, the carriage supports the drive coil arrangement on its side opposite the permanent magnet arrangement on the stator, while the reversed arrangement is also possible, i.e. in that case the carriage supports the permanent magnet arrangement and the stator the drive coil arrangement. 
     In an advantageous manner the stator, which in particular is embodied as an extruded profile or continuously cast profile, has adjustable fixation means for the guide rails, which preferably can be fixed in place in longitudinal grooves of the stator by means of adjustable sliding blocks. In this way the guidance element can be aligned in two planes and a two-dimensional alignment is made possible. In the process it is possible to compensate for manufacturing tolerances. 
     The carriage is guided on the guide rails by means of two, preferably three or four, guide elements, which cooperate in a positively connected manner with the guide rails in such a way that only a relative movement in the linear direction of the guide rails is possible. Because of this, the direct linear drive device can be mounted and operated in any desired spatial orientation. In this case the guide elements are preferably embodied in the form of revolving ball guide elements. 
     Tolerance fluctuations in regard to the angle assignment of the guide rails, or respectively the guide elements, can be advantageously compensated in that the guide elements are embodied so they can be fixed in place by means of curved angle compensating elements, or angle compensating areas, on correspondingly curved compensation surfaces or compensation recesses. 
     A perfect compensation of tolerances and heat expansions is achieved by means of a hinged carriage. To this end, the carriage advantageously has carriage areas which are connected with each other via a pivot shaft extending parallel with the guide rails, and to which the guide elements themselves are hingedly attached. It is possible by means of this to also compensate tolerances over the entire length of the stroke, even in the course of movement. In this case the carriage areas are embodied to be plate-shaped in order to form mounting areas in the same way as with a rigid embodiment. For a hinged installation of the guide elements, these are preferably fixed in place on holding elements, or holding plates, hingedly attached to the carriage areas. 
     For achieving a fixed angle of preferably 90° between the two mounting faces, which is to be maintained regardless of the heat expansion of the carriage, the first carriage area of the carriage, which can be acted upon by the driving force, is rigidly connected with a plate-like carriage area which is arranged at right angles to it and extends over the second carriage area, which is embodied to be of one or two pieces, or is arranged in essentially the same plane with it. In this case this plate-like carriage area constitutes a mounting area, whose angle in respect to the first carriage area, which also constitutes a mounting area, is always maintained, while angular changes between the first carriage area and the second carriage area have no effect on the mounting areas. 
     In an advantageous manner, a position measuring device for scanning position markings arranged along the stator is also arranged on the carriage and can, for example, have a sensor arrangement sensitive to a magnetic field, while the position markings are embodied as magnetic markings. 
     In an advantageous further development of the invention, a linear channel through the stator contains a piston, which is mechanically or magnetically connected with the carriage and can be designed as a drive piston or gravitation-compensating device. 
     In order to keep heat expansions as low as possible, in particular in connection with a rigid embodiment of the carriage, the carriage consists of a material with a low coefficient of heat expansion, for example steel, or a steel alloy, and/or of carbon-reinforced fiber and/or a corresponding compound material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the invention are represented in the drawings and will be explained in greater detail in the following description. Shown are in: 
         FIG. 1 , a perspective representation of the electrical direct linear drive device as an exemplary embodiment of the invention, 
         FIG. 2 , a cross-sectional representation of the electrical direct linear drive device with a schematically represented, hingedly-embodied carriage, 
         FIG. 3 , a perspective plan view of the hingedly-embodied carriage, 
         FIG. 4 , a cross-sectional representation with a schematically represented, hingedly-embodied carriage, in which a rigid mounting plate extends over one carriage area, 
         FIG. 5 , a perspective representation of a rigidly embodied carriage, on whose inside four angle-compensation cutouts are arranged, 
         FIG. 6 , an enlarged representation of a guide rail fixed in place on the stator, around which a guide element extends, in a sectional representation, and 
         FIG. 7 , a corresponding representation, in which the guide element is embodied as a revolving ball guide element with a curved angle compensation element. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The electrical direct linear drive device represented in  FIG. 1  has an oblong stator  10 , along which a carriage  11  is movably guided. Two guide rails  12 ,  13 , which have been arranged on adjoining, differently oriented sides of the stator, have been attached to the stator  10  for guiding the carriage  11 , namely one of the guide rails,  12 , on the top  14  of the stator  10  and the other guide rail  13  on one of the adjoining narrow sides, namely on the narrow side  15 . In this case the guide rail  12  is attached to the edge area of the top  14  which is distant from the narrow side  15 , so that the two guide rails  12 ,  13  are positioned as far apart from each other as possible. Since the top  14  essentially assumes an angle of 90° in regard to the narrow side  15 , the guide rails  12 ,  13  are correspondingly offset by an angle of 90° in respect to each other. Accordingly, the carriage  11  has an L-shaped cross section, wherein the larger, plate-like leg constitutes a first carriage area  16  and extends over the top  14 , while the smaller, plate-like leg constitutes a second carriage area  17  and extends over the narrow side  15 . The two carriage areas  16 ,  17  are rigidly connected with each other, for example as one piece, and the carriage areas  16 ,  17  are arranged at right angles in relation to each other. 
     The carriage  11  is conducted on the guide rails  12 ,  13  by means of guide elements, not visible in  FIG. 1 , which are arranged on the insides of the carriage  11  and which will be described in greater detail in connection with the further drawing figures. 
     In a manner known per se, for one a permanent magnet arrangement  18  consisting of a plurality of permanent magnets lined up with each other and extending over the entire length of the stator  10  is employed for the electrical drive of the carriage  11 , and on the other hand a drive coil arrangement  19  which works together with the former and is arranged on the inside of the first carriage area, but cannot be seen in  FIG. 1  because of the perspective exterior view. It will be shown in connection with the subsequent drawing figures. Such a drive arrangement is for example known from the prior art recited at the outset. 
     For the excitation of the drive coil arrangement  19 , the carriage  11  has an electrical connection arrangement  20  in the second carriage area  17 , which is connected via supply lines  21  with an electrical control device, not represented. Since during its operation the carriage  11  is moving, the supply lines  21  must be appropriately carried along, for example by means of a drag chain. Alternatively to this, the connection arrangement  20  can also be provided at a different location, for example in the first carriage area  16 . 
     A reversed arrangement is also possible in principle, i.e. the elongated drive coil arrangement is located on the stator  10 , while the carriage  11  supports the permanent magnet arrangement. 
     On its two remote ends, the stator  10  is provided with cover plates  22 ,  23 , which support end stop members  24  for the carriage  11 . These end stop members  24  can also be designed as end stop dampers. 
     The flat outsides of the carriage areas  16 ,  17  visible in  FIG. 1  are used as mounting faces for loads, or respectively installations, to be moved by means of the carriage  11 , while other ancillary equipment, such as cooling bodies, electrical connection arrangements  20 , drag chains, and the like, can be attached. Furthermore, these carriage areas  16 ,  17 , the first carriage area  16  in particular, can be used for mounting the carriage  11  at a fastening point, in which case the stator  10  is moved relative to the carriage  11  and has, for example, a load, or respectively an object to be moved, at one or both ends. 
     The stator  10  is represented in cross section in  FIG. 2 , it is embodied as an oblong profiled body, for example as a profiled extruded or cast part, and consists for example of aluminum or an aluminum alloy. For fixing the two guide rails  12 ,  13  in place, the stator  10  has respective longitudinal grooves  25 ,  26  on the top  14  and the narrow side  15  wherein, in accordance with the detailed representation in  FIG. 6 , the guide rails  12 ,  13  are fixed in place by means of holding screws  27 , which are screwed together with sliding blocks  28  inserted into the longitudinal grooves  25 ,  26 . Depending on the length of the guide rails  12 ,  13 , a more or less large number of holding screws  27  and sliding blocks  28  is employed for this. 
     The sliding blocks  28  have a narrower profile in relation to the longitudinal grooves  25 ,  26 , so that a certain adjustment of the guide rails  12 ,  13  for compensating manufacturing tolerances and other tolerances is made possible by means of the play between the sliding blocks  28  and the longitudinal grooves  25 ,  26 . This is of particular importance in case of a rigid carriage  11  as represented in  FIG. 1 . Because of the possibility of adjustment, re-milling of the support faces for the guide rails  12 ,  13  is not required. 
     With articulated carriages, such as represented in  FIGS. 2 to 4 , an alignment and adjustment of the guide rails  12 ,  13  is not absolutely, or not at all, required. It is therefore also possible, for example, to employ guide rails fixedly connected with the stator, for example rolled on, welded on, soldered on, pressed on or glued on guide rails. 
     The carriage  30  represented in  FIG. 2  has two carriage areas  32 ,  33 , which are connected with each other via a hinge  31 . In turn, these carriage areas  32 ,  33  are connected via hinges  34 ,  35  with guide elements  36  which, in the exemplary embodiment, are embodied as revolving ball guide elements, such as are known from DE 35 37 728 A1, for example. These guide elements  36  have a substantially U-shaped profile and extend with their legs around the guide rails  12 ,  13 . In the center area, the guide rails  12 ,  13  have groove-like depressions  37  in their two oppositely located exteriors, which are engaged by the free end areas of the legs of the guide elements  36 , so that they extend in a certain manner behind the guide rails  12 ,  13 . This results in the guide elements  36  being able to move only in the longitudinal direction of the guide rails  12 ,  13 , while all other movements in other directions are guided in a positive manner. Such an embodiment of the guide elements need not absolutely mean a design in the form of revolving ball guide elements, other types of guidance, such as a sliding guidance, are also possible instead. 
     The carriage areas  32 ,  33  are dimensioned in such a way that together they essentially again form an L-profile. The angle can slightly change as a result of heat expansion of the carriage  11 , which during operation becomes heated to approximately 100° C. or more. 
     To keep heat expansion as low as possible, a material with a low coefficient of heat expansion is selected as the material for the carriage  30 , and particularly for the carriage  11 , for example steel, or a steel alloy, or a plastic material, such as carbon-reinforced fiber, or a compound material. In the case of the carriage  30 , one of the carriage areas  32 ,  33  can also consist of steel or a steel alloy, and the other carriage area of carbon-reinforced fiber. 
     The top  14  of the stator  10  has a flat depression for receiving the permanent magnet arrangement  18 . The latter has a pre-fabricated strip-shaped form and, for fixation in place on the stator  10 , one of its longitudinal sides is pushed behind a strip-shaped holding protrusion  38  and, on the oppositely located longitudinal edge area, is screwed together with sliding blocks, not represented in detail, which can be inserted in an appropriately arranged longitudinal groove  39 . 
     The drive coil arrangement  19  is mounted and maintained on the underside of the first carriage area  32 , or respectively in accordance with  FIG. 1 , of the first carriage area  16 . It is located at a small distance directly opposite the permanent magnet arrangement  18 . 
     A circular-cylindrical connecting conduit  40  extends in the longitudinal direction through the profile of the stator  10 . It is used for receiving a piston, not represented, for example a piston without a piston rod, and serves as a fluidic supplemental drive for the carriage  30 , or respectively the carriage  11 . Such a fluidic supplemental drive for an electrical linear drive device is known, for example, from EP 1404011 A1. In the present case, the piston is magnetically or mechanically coupled with the carriage  30 , or respectively  11 . For the mechanical coupling, the connecting conduit  40  has a slit  41 , open toward the top, through which a mechanical connecting member, not represented, for the carriage extends through the carriage, while otherwise the carriage is sealed by means of a sealing strip, such as is represented and described in the cited prior art. The slit  41  is omitted in the case of a magnetic coupling. 
     A piston in the connecting conduit  40  can also be used for gravitation compensation. In this case the connecting conduit  40  is connected via one of the cover plates  22 ,  23  with a fluid volume  42 , which also extends in the shape of linear channels within the profile of the stator  10 . The volume in the connecting channel  40  is changed by the movement of the piston, while as a result of the connected fluid volume  42  only a small pressure difference respectively occurs. A pneumatic spring is constituted by this arrangement as a whole. 
     A fluidic supplemental drive or the fluidic return flow device are optional devices and are not absolutely required for the arrangement in accordance with the invention. 
     The carriage  30  is represented perspectively and in greater detail in  FIG. 3 . On its two corner areas remote from the second carriage area  33 , the first carriage area  32  has holding plates  43 ,  44  for the hinged attachment of two guide elements  30 , which are arranged, pivotable by means of the hinge  34 , in appropriate cutouts. 
     The second carriage area  33 , connected via the hinge  31  with the first carriage area  32 , is made in two parts, wherein each partial area  33   a  and  33   b  has pivotable holding plates  45 ,  46  on its free end for the attachment of guide elements  36 . The holding plates  45 ,  46  are here pivotably connected with the partial areas  33   a  and  33   b  via the hinge  35 , designed to have two parts. A rigid mounting plate  47 , connected at right angles with the first carriage area  32 , is arranged between the partial areas  33   a  and  33   b . The former can also be connected in one piece with the first carriage area  32 . 
     In accordance with  FIG. 3 , four guide elements  36  can be attached to the carriage  30  at the four holding plates  43  to  46 . In principle these could also only be three guide elements  36 . In this case either a centered holding plate takes the place on the first carriage area  32  instead of the two holding plates  43 ,  44 , or, in place of the holding plates  45 ,  46  one holding plate, centered on the second carriage area  33  embodied in one piece, which either extends over the entire width, or which is framed by two rigid mounting plates in the same plane. 
     A further embodiment of a carriage  50  is represented in  FIG. 4 . Here again, a first carriage area  51 , which supports the drive coil arrangement  19 , is connected via a hinge  52  with a second carriage area  53 . Again in accordance with  FIG. 2 , the end areas, remote from the hinge  52 , of these carriage areas  51 ,  53  are pivotably connected via hinges  54 ,  55  with guide elements  36 . The hinged connections can be embodied in accordance with  FIG. 3 , for example. In contrast to  FIG. 2 , the first carriage area  51  is slightly overextended, while a mounting plate  56  is fixed in place at right angles and rigidly on the free end of the overextending area. Thus, this extends over the second carriage area  53  and the guide elements  36  attached thereto. 
     In this embodiment the first carriage area  51 , together with the mounting plate  56 , forms two mounting faces arranged at right angles in respect to each other, wherein this angle is always maintained independently of heat expansion. In the direction of movement, the mounting plate  56  always has the same extension as the first carriage area  51 , and thus as the carriage  50  itself. In accordance with  FIG. 2 , the second carriage area  53  can be designed in two parts, or also as a single part wherein, with a single-part embodiment, the second carriage area  53  can have a length in the direction of movement which corresponds to that of the first carriage area  51 , and can have one or two pivotable holding plates, or this second carriage area  53  is merely embodied in the form of a narrow plate or strip and arranged centered. In principle, in accordance with  FIG. 3  the two partial areas  33   a ,  33   b  can also be embodied in the form of narrow strips or rods. 
     The rigid carriage  11  in accordance with  FIG. 1  is represented in greater detail in  FIG. 5 . Four curved compensation recesses  57  to  60  for receiving guide elements in accordance with  FIG. 7  are arranged on the insides of the two carriage areas  16 ,  17  facing the stator  10 . On their sides facing the carriage, these guide elements  36  have correspondingly curved angle compensation elements  61 , with which they are mounted in the compensation recesses  57  to  60 , for example screwed or glued in. By means of this it is possible to compensate angular errors of the guide rails  12 ,  13 , or respectively of the stator  10 , as an additional compensation of the sliding blocks  28 , which are arranged with play. The compensation recesses  57 ,  58  are arranged on the first carriage area  16  in the corner areas remote from the second carriage area  17 , while the compensation recesses  59 ,  60  on the second carriage area  17  are also arranged in opposite edge areas, but substantially centered there. 
     Basically, an opposite arrangement is also possible, i.e. the guide elements  36  are provided with compensation recesses, while correspondingly curved angle compensation elements are attached to the carriage areas  16 ,  17 . 
     A holding receptacle  62  for receiving a position measuring device is arranged between the compensation recesses  57 ,  58  in the first carriage area  16 . For example, this can be embodied in a known manner as a device sensitive to magnetism, for example as a Hall sensor arrangement, which works together with a tape or lath arrangement on the stator  10  which is magnetized in the form of strips. Optical markings, which are appropriately optically scanned, can also take the place of magnetic markings. 
     In order to avoid experiencing problems of control technology in regard to position measuring because of a construction affected with play, the first carriage area  16 , or respectively its holding receptacle  62 , is rigidly connected with the measuring system and the drive coil arrangement  19  via the position measuring device. Because of this, possible axial play of the hinges does not present a problem.

Technology Category: 2