Abstract:
In a linear guide unit that has an elongated guide housing which limits a guide hollow space with a longitudinal opening, a wagon arrangement which is displaceably guided in the guide hollow space on guide rails, a connection part for connecting the wagon arrangement to an object to be guided, a cover element arranged between movement tracks of the connection part and covering the longitudinal opening, in accordance with the present invention forwardly of and/or rearwardly of the wagon arrangement, at least one support unit is arranged displaceably in direction of the longitudinal axis for supporting the cover element relative to the guide housing; also additionally or alternatively the support unit can support the cover element relative to the wagon arrangement.

Description:
BACKGROUND OF THE INVENTION 
   The present invention generally relates to linear guide units. 
   More particularly, it relates to a linear guide unit which has an elongated guide housing with a longitudinal axis and with walls which limit a guide hollow space and has free ends which limit at least an longitudinal opening of the guide hollow space, two guide rails provided in the guide hollow space each for displaceably guiding a wagon in direction of the longitudinal axis, a connection unit for connecting the wagons to a wagon arrangement, a connecting part extending through the longitudinal opening and connecting the wagons to an object to be guided in direction of the longitudinal axis, and a cover element arranged between movement tracks of the connection part and covering connection units of the guide housing located at its ends and also the longitudinal opening. 
   Such a linear guide unit is disclosed for example in the German patent document DE 197 38 988 A1. With this linear guide arrangement the cover element is held with a pulling stress on the connection units of the guide housing located at the ends. Thereby a sagging of the cover element must be prevented, since the wagon arrangement otherwise during its movement on the cover plate would slide at least over a part of its movement path, which would lead to an undesirable noise generation during the operation of the linear guide unit. It has been shown however in practice that setting of the cover element under the pulling stress represents an efficient measure against a sagging of the cover element only to a certain maximum length. For long linear guide units the cover element slides on the wagon arrangement. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the present invention to provide a linear guide unit which is a further improvement of the existing linear guide units of this type. 
   More particularly, it is an object of the present invention to provide a linear guide unit which in the case of great structural lengths generates a low noise or no noise at all. 
   In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a linear guide unit in which before or/and after the wagon arrangement, at least one supporting unit is provided which is displaceable in direction of the longitudinal axis and supports the cover element relative to the guide housing, and/or a support element is provided on the connection unit and supports the cover element relative to the wagon arrangement. 
   By means of these support units, the non supported free path lengths of the cover element can be maintained so small, that a sagging of the cover element due to gravity between two neighboring support units, which can represent the danger of a sliding contact with the wagon arrangement, must not be feared anymore. As known from German patent document DE 197 38 988 A1, the cover element can be held with a pulling stress between the end connection units to further reduce this danger. 
   It is to be understood that the connection of the wagons by the connection unit to a wagon arrangement can be obtained also by a one-piece construction. For example the wagon arrangement can be produced from an aluminum extrusion profile with inserted plates of steel. 
   For further reduction of noise generation, in particular during movement of the supporting units along the cover element, at least one sliding element can be provided between the at least one supporting unit and the cover element. For example, the sliding element can be arranged on the supporting unit, wherein in addition felt can be used as cost-favorable material for the slide element. 
   The inventive supporting unit can be used for example with linear guide devices, whose drive device for movement of the wagon arrangement in direction of the longitudinal axis includes a rod unit which is a in driven alternating connection with the rod arrangement or is bringable into such a connection. For example the linear unit can be driven by a roll body thread drive with a threaded spindle as the rod unit. Alternatively, the linear unit can be a magnetic piston unit with a runner which is arranged reciprocatingly movable along a rod, wherein the rod is formed as a hollow tube in which a magnetic piston is displaceable under the action of pressure fluid, and the runner is connected with the piston by magnetic forces. As a further alternative, the linear unit can be formed as a linear module with a runner which is arranged reciprocatingly movable around a rod, wherein the rod is formed as a displacement rod of a linear motor driven by the runner. 
   In all embodiments the support unit can be connected with a support arrangement or formed of one piece with it, for supporting the rod unit relative to the guide housing. The support arrangement can be formed for example as in German patent document DE 100 02 849 A1, whose complete content is incorporated here by reference for completion of the disclosure of the present application. 
   In accordance with a further embodiment of the invention, the support unit can have a substantially T-shaped construction in a section which is perpendicular to the longitudinal axis. Thereby with a relatively low space consumption by means of the vertical web of the T-shape, a broad support for the cover element can be provided by the transverse web of the T-shape. When the free ends of the transverse web of the T-shape in addition engage in associated grooves of the cover element, preferably in a form-locking manner, then the cover element can be thereby secured not only against a gravity-related sagging. 
   With the engagement of the transverse web of the T-shape into the grooves of the cover element it is further possible to secure it against lateral displacements. Whereby an undesirable engagement with the connection parts of the wagon can be prevented. A lifting of the cover element can be stopped with this engagement. Therefore the inventive linear guide unit can be mounted for example also in an overhead position. For further noise reduction, sliding elements can be provided on the engaging surfaces on the free ends of the transverse web of the T-shape with the grooves of the cover element, for example with felt elements. 
   In accordance with a further embodiment of the present invention a linear guide unit has an elongated guide housing with a longitudinal axis and with walls which limit a guide hollow space and has ends which limit at least one longitudinal opening of the guide hollow space, at least one guide rail in the guide hollow space for displaceably guiding a wagon in direction of the longitudinal axis, connecting part extending through the longitudinal opening and connecting the wagon in direction of the longitudinal axis to an object to be guided, and a cover band which covers the movement path of the connecting part in direction of the longitudinal axis before or/and after the wagon. 
   In this linear unit the cover band can have a substantially U-shaped cross-section with the free legs of the U-shape which are for example notched or toothed. With this notched or toothed construction, the cover band obtains a higher stability that assists in preventing in particular a displacement of the cover band in the guide hollow space due to application of outer force. When the longitudinal grooves which receive the side edges of the cover band correspond to the geometry of the angle side edges, the above mentioned guiding stability can also be secured by the form-locking cooperation of the free ledges of the U-shape with the guide groove. 
   A further feature of the invention deals with a mounting of the cover band on the wagon. When the base part for mounting a free end of the cover band on the mounting unit which operates as a wagon and the holding part of the mounting unit are connected of one piece with one another, for example by an elastic web, the mounting of the cover part on the wagon is significantly simplified since the mounting part can not be lost and must not be handled in a special way. 
   In accordance with a further feature of the present invention, a stripping unit is provided on at least one of the end connection units of the guide element, for stripping dirt which is located in the cover band. The stripping unit can be provided with an inclined surface which is set as a blade against the surface of the cover band. 
   The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective, partially sectioned view of a linear guide unit in accordance with the present invention; 
       FIG. 2  is an end view of the linear guide unit of  FIG. 1 , as seen in direction of the arrow  2  in  FIG. 1 ; 
       FIG. 3  is a view showing a detail A of  FIG. 2  on an enlarged scale 
       FIG. 4  is a perspective view of a U-shaped cover band of the inventive linear guide unit; 
       FIG. 5  is a view showing a partial section of the cover band of  FIG. 4  in cooperation with a receiving guide groove; 
       FIG. 6  is a detailed view of the linear guide unit for illustration of mounting of the cover band on a wagon; and 
       FIG. 7  is a view showing a stripping element for cleaning the cover band of the inventive linear guide unit. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 and 2  shows an inventive linear guide arrangement which is identified as a whole with reference numeral  10 . It includes a guide housing  12  with a bottom wall  14  and two side walls  16  provided on its free ends with upper edge flanges  18  which are oriented toward one another. Guide rails  20  are received in guide grooves  22  on the bottom wall  14  of the guide housing  12 . The base of the left guide rail  20  in  FIG. 2  is laterally movably received in a longitudinal groove  22  to avoid double fits, as known for example from German patent document DE 197 28 988 A1. 
   The guide rails  20  are mounted on the bottom wall  14  by a not shown bolts with bolt heads arranged so that they sink in sunk openings of the rail head surface. A wagon  24  is rollingly guided on each guide rail  20 . The construction and the operation of the wagons  24  are known and therefore not described in detail. 
   The wagon  24  of the left side and the wagon  24  of the right side are connected by a connection yoke  26  that can be made of one piece with the main bodies of the wagons  24 . The connection yoke  26  receives a ball screw nut of a spindle drive with a fixed seat, whose thread spindle  28  extends in a longitudinal direction L of the linear guide unit  10 . The threaded spindle  28  is set in rotation by a not shown motor around its axis which extends parallel to the longitudinal direction L. Thereby with interposition of the thread nut the wagon arrangement  30  formed by the wagons  24  and the connecting yoke  26  can be reciprocatingly moved in a longitudinal direction L of the linear guide unit  10 . 
   A connecting part  32  is mounted on each wagon  24 . It extends outwardly through the longitudinal openings  34  of the guide housing  12 , which is limited by both edge flanges  18 . The connecting parts  32  serve for connection of objects to be guided by the linear guide unit  10  for example tools. 
   Some covering features are provided for protecting an inner space  36  which is surrounded by the guide housing  12  from penetration of dust, in particular particles. First of all, a cover profile  40  is mounted on the end connecting units  38  of the guide housing  12  preferably with a pulling force, to cover the longitudinal openings  34  between the movement paths of the connecting parts  32 . Secondly, cover bands  42  are mounted on the connecting parts  32  for covering the movement paths of the connecting parts  32  in the longitudinal direction L before or after them. The cover bands  42  are guided in longitudinal grooves  18   a  and  40   a  of the edge flanges  18  of the guide housing  12  and the cover profile  40 . Furthermore, the cover bands  42  in the region of the end connecting units  38  slide around the not shown deviating rollers and are guided back through recesses  14   a  in the bottom of the right housing  12  to each other end of the connecting part  32 . 
   The above described inventive linear guide unit  10  with the features specified above corresponds with its construction and operation to the known linear guide unit which is disclosed in German patent document DE 197 38 988 A1. In order to complete the description, in particular with respect to the description of details of the construction and operation, this German reference DE 197 38 988 A1 is here incorporated as a reference. 
   In accordance with the present invention before and/or after (in front of and/or behind of) the wagon arrangement  30 , supporting units  50  are provided for preventing a gravity-caused sagging of the cover profile  40  in long linear guide units  10 , in particular linear guide units with a length more than 1.8 m. The supports unit  50  are mounted in the shown embodiment on its support arrangements  52  which support the thread spindle  28  on the guide housing  12 . For this purpose the support arrangement  52  engage with the edge flanges  52   a  in corresponding longitudinal grooves  14   b  of the bottom wall  14  of the guide housing  12 . 
   The support arrangements  52 , with their substantial structural features and their functions, in particular concerning the “take off” and “pick up” by the wagon arrangement  30 , are formed as disclosed in the German patent document DE 100 02 849 A1, which for completion of the description of the present application is incorporated here as a reference. 
   As can be seen in particular from  FIG. 2 , the support units  50  are mounted on the support arrangements  52 . The support units  50  are substantially T-shaped and have a transverse web  56  and a vertical web  58 . The vertical web  58  serves for mounting the support unit  50  on the support arrangement  52 , while the transverse web  56  serves for supporting the cover profile  40 . As can be seen in particular from  FIG. 3 , felt slide elements  60  an the upper side  56   a  of the transverse web  56  are received in receiving depressions  56   b  which are in sliding contact with the cover profile  40 . 
   Thereby the cover profile  40  on the one hand prevents sagging due to gravity force and on the other hand prevents a noise generation by the relatively cost favorable material felt when the support unit  50  together with the wagon arrangement  30  move along the cover profile. Supplementary an inventive support unit  50 ′ can be also arranged on the wagon arrangement  30 , in particular the connection yoke  26 . 
   The transverse web  56  of the support unit  50  has free ends  56   c  (only one shown in  FIG. 3 ), and engages with the free ends into a longitudinal groove  40   b  of the cover profile  40 . It is to be understood that in the region of the free end  56   c , sliding elements  60  can be provided for supporting the cover profile  40  against a gravity-caused sagging. In the embodiment shown in  FIG. 3 , in the region of the free ends  56  a further felt sliding element  82  is received in a recess  56   d  of the lower side  56   e  of the transverse web  56 . It is in sliding and supporting contact with a counter surface  40   c  of the longitudinal groove  40   a  of the cover profile  40 . 
   Based on the above described construction, the support unit  50  can support the cover profile  40  from gravity-caused sagging not only in the orientation shown in the drawings, but also in an overhang orientation, or in other words with the downwardly facing longitudinal opening  34 . Finally, it is also possible to provide further sliding elements, which are not shown in the drawings, in the region of the lateral limiting surface  56   f  of the transverse web  56 . They avert a danger of a lateral displacement of the cover profile  40  relative to the support unit  50  and thereby relative to the wagon arrangement  30 . 
   While felt is proposed as the material for sliding element  60  and  62 , it is believed to be understood that also other suitable materials can be used for forming the sliding elements, for example TEFLON. 
   Additionally, the lug  40   d  serves for mounting of the cover profile  40  on the connection parts  38 . Furthermore, the box-shaped construction of the cover profile  40  with its hollow profile sections increases the strengths and thereby reduces the tendency for sagging of the cover profile  40 . 
   In accordance with the present invention instead of the cover band  42  which is substantially flat and showed in  FIG. 1 , a U-shaped cover band  42 ′ can be used as shown in  FIG. 4 . With the cover band  42 ′, the free webs  32   a ′ of the U-shape are notched or toothed to allow bending of the cover band  42 ′ around a transverse axis Q which extends in the band plane E and is perpendicular to the longitudinal direction A. The bending is required for example for deviating the cover band  42 ′ in the region of the connection caps  38  or, as will be explained herein below with reference to  FIG. 6 , for mounting on the wagons  24 . 
   The U-shaped construction of the cover band  42  has the advantage in that it provides the increase of the stability of the cover band  42 ′, in particular an increase of its guiding stability in the longitudinal grooves  18 ′ a  or  40 ′ a  of the edge flanges  18  of the guide housing  12  and the cover profile  40 , as shown in  FIG. 5 . In particular, with the corresponding construction of the longitudinal grooves  18 ′ a  and  40 ′ a  with a form-locking cooperation of these longitudinal grooves with the cover band  42 ′, the cover band will not be able to move out of the longitudinal grooves. 
     FIG. 6  shows a mounting unit  70  which is used for mounting of the cover bands  42  and  42 ′ on the wagon  24 . With the use of the mounting unit  70 , the base part  74  which is mounted by a screw bolt  72  on the wagon  24  is formed of one piece with the mounting or clamping part  78  via an elastic web  76 . The elastic web  76  serves as a protection from losing of the clamping part  78  and allows turning on the clamping part  78  from the base part  70  for facilitating the insertion of the cover band  42  into an intermediate space  80  formed between the base part  74  and the clamping part  78 . Preferably the free ends of the cover band  42  can be placed around a support part  82 . The support part  82  can cooperate in a form-locking manner with a bolt  84  which mounts the clamping part  78  on the base part  74 . This increases the clamping efficiency based on the placement of the cover band  42  around the support part  82  and facilitates the accompanying doubling of the clamping points. On the other hand, the support part  82  has an increased head  82   a  which, with applying a pulling stress on the cover band  42 , additionally form-lockingly opposes a movement out of the gap  80 . 
   Finally, in the region of the connection cap  38  and in particular at the side identified in  FIG. 1  with reference numeral  1 , a stripping element  90  is provided as shown in  FIG. 7 . The stripping element  90  is set with an inclined face  92  against the surface of the cover band  42  and  42 ′ to strip dirt located on the cover band  42 . The stripping element  20  can be pre-stressed at the lower side which faces the cover band  42  and  42 ′, by a sealing element. The sealing element can be composed for example of felt and increases the stripping action of the inclined face  92 . 
   It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
   While the invention has been illustrated and described as embodied in linear guide units, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
   Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention. 
   What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.