Abstract:
A concrete paving machine for leveling concrete having a frame and at least one dowel apparatus carried by the frame. The at least one dowel apparatus is movable along a working width of the concrete paving machine in a direction perpendicular to a paving path. The at least one dowel apparatus includes a vibration device and a dowel distribution device. The dowel distribution device comprises a series of longitudinal members having L-shaped profiles. Each longitudinal member forms a predetermined pattern of recesses wherein the series of longitudinal members are slidably arranged so that in an unlocked position, the recesses of each longitudinal member are aligned so as to permit distribution of at least one set of dowel bars. In a locked position, each longitudinal member is arranged to so that the recesses are misaligned so as to prevent distribution of at least one set of dowel bars.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a concrete paving machine, more particularly a machine for levelling concrete, of the type whereby poured concrete is spread over a pre-determined width and this concrete is equalled at a well-defined thickness. 
     2. Description of the Related Art 
     As known, such concrete paving machines are applied for spreading and equalling of concrete, with the intention of forming a floor, plate, road or similar, whereby either or not simultaneously certain profilings can be provided in the formed road, such as a drain, an upstanding edge, a concrete crash barrier, or similar. 
     It is known that such concrete paving machines generally are composed of a movable frame under which a number of tools is fixed, the aim of which is to distribute the concrete poured in front of the machine, more or less equalling it, vibrating and finally drawing it equal, such that after passing of the concrete paving machine, a completely finished road is created, whereby hereafter one only has to wait for the hardening of the concrete, and eventually provided extension joints will have to be filled. 
     It is known to equip such concrete paving machines also with a dowel apparatus for providing dowels in the concrete, mostly at the height of the extension joints. Such dowels are reinforcing bars, mostly with a length of approximately 0.5 meters, which are provided in the concrete in the longitudinal direction of the road. Mostly, a whole series of such dowels is provided next to each other, at mutual distances of 20 to 30 cm. 
     The dowel apparatuses applied hereby are apparatuses which allow to position such series of dowels above the concrete next to each other and to vibrate these dowels subsequently into the concrete. Hereby, the dowel apparatuses are suspended at the concrete paving machine in such a manner that they can remain stationary for a certain period of time in order to vibrate the dowels into the concrete, during which the actual concrete paving machine slowly moves further. 
     Known embodiments of concrete paving machines with dowel apparatuses are described in EP 0.051.885, EP 0.196.698, and DE 3.811.186. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention has a concrete paving machine as its object which is improved in respect to the known embodiments. 
     To this aim, the invention aims at a concrete paving machine of the above-mentioned type, with as a characteristic that the concrete paving machine is provided with at least one dowel apparatus, whereby this dowel apparatus is movable according to the working width. 
     As the dowel apparatus is movable, the advantage is created that the dowel apparatus must not necessarily extend over the entire maximum working width of the concrete paving machine, as a result of which this dowel apparatus can be kept small and light-weight in relation to the dimensions of the entire concrete paving machine. The dowel apparatus which, as will become clear from the further description, is rather complex and also takes up relatively much space in the height, then can, due to its relatively small width, easily be transported to the site where it has to be used or can easily be mounted permanently at the concrete paving machine. 
     According to a particular embodiment of the invention, the dowel apparatus is mounted to the paving machine at such a height that it is located at a distance above the upper surface of the levelled concrete, resulting in that there is no contact between the concrete and the lower portion of the dowel apparatus. In this way, amongst others, the advantage is attained that the frame of the dowel apparatus cannot cause irregularities in the surface of the concrete, contrary to the devices disclosed in EP 0.051.885, EP 0.196.698 and DE 3.811.186, in which at the location of the dowel apparatus always a slide is provided which is in contact with the concrete. 
     A feature that the dowel apparatus is mounted freely above the concrete is particularly advantageous in combination with the dowel apparatus which is movable according to the working width, but, according to the present invention, can also be applied in concrete paving machines having a dowel apparatus which is not movable according to the working width, for example, a dowel apparatus extending over the complete width of the machine. 
     According to another particular feature of the invention, the machine is provided with means for automatically controlling and adjusting the distance between the lower portion of the dowel apparatus and the surface of the levelled concrete. These means may consist of detection means to control the height of the dowel apparatus in respect to the upper surface of the concrete and of driving means to bring at least a lower portion of the dowel apparatus at the required height. Preferably, the adjustment is done automatically, such that the distance remains constant. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     With the intention of better showing the characteristics according to the invention, hereafter, as examples without any limitative character, several preferred forms of embodiment are described, with reference to the accompanying drawings, wherein: 
     FIG. 1 schematically represents a concrete paving machine according to the invention; 
     FIG. 2 represents a view according to arrow F 2  in FIG. 1; 
     FIG. 3 represents a variant of the concrete paving machine, in top view; 
     FIG. 4 represents the concrete paving machine from FIG. 3 in another position; 
     FIG. 5 represents another concrete paving machine according to the invention, in top view; 
     FIG. 6 represents the concrete paving machine from FIG. 5 in another position; 
     FIG. 7 represents the concrete paving machine from FIG. 5 in transport condition; 
     FIG. 8 schematically represents a view according to arrow F 8  in FIG. 6; 
     FIG. 9, at a larger scale and more detailled, represents the portion which is indicated by F 9  in FIG. 8; 
     FIG. 10 represents a view according to arrow F 10  in FIG. 9, for a somewhat different position; 
     FIG. 11 in perspective represents a view of the portion which is indicated by arrow F 11  in FIG. 9; 
     FIG. 12 represents a cross-section according to line XII—XII in FIG. 11; 
     FIGS. 13 and 14 represent cross-sections according to lines XIII—XIII and XIV—XIV in FIG. 12, respectively; 
     FIG. 15 represents the lowermost portion from FIG. 12 in another condition; 
     FIG. 16 represents a cross-section according to line XVI—XVI in FIG. 15; 
     FIG. 17 represents a variant of a carriage which can be applied in the portion from FIG.  11 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As represented in FIGS. 1 and 2, the invention relates to a concrete paving machine  1  for levelling concrete  2 , of the type whereby poured concrete  2  is spread over a pre-determined width and this concrete  2 , in order to form a road  3  or similar, is equalled at a well-defined thickness or in a well-defined shape. 
     Amongst others, such concrete paving machine  1  consists of a frame  4  and support means which allow to move and/or to roll away this frame  4  which, in this case, consist of four support elements,  5 - 6 - 7 - 8  respectively, which are provided with, for example, tracks  9  which are driven by means of motors, not represented in the figures, more particularly, hydraulic motors which are provided at the height of each support element  5 - 6 - 7 - 8 . 
     In this case, the support elements  5 - 6 - 7 - 8  are pivotable around the corners of the concrete paving machine  1 , as they are attached at pivotable arms  10 - 11 - 12 - 13 , as a result of which the whole can be switched between a working position, such as represented in FIG. 2 in full line, and a transport position which is represented in a dash-dot-line. 
     At the frame  4 , and possibly also at the support elements  5 - 6 - 7 - 8 , various tools, in this case, five, are attached. More particularly, in this case, it concerns a device  14  for spreading the concrete  2 , a device  15  for vibrating the concrete  2 , a shaping piece  16  for giving a shape to the concrete  2 , a dowel apparatus  17  for bringing dowels  18  into the concrete  2 , and a smoothening device  19  in order to provide for a smooth finishing. For clarity&#39;s sake, these tools  14 - 15 - 16 - 17 - 19  are depicted only in a very schematic manner. Hereby, it is also obvious that not all aforementioned tools  14 - 15 - 16 - 17 - 19  necessarily have to be present and that possibly still other tools may be provided at the concrete paving machine  1 . 
     The particularity of the invention consists in that the aforementioned dowel apparatus  17  is movable according to the working width B. 
     As indicated schematically in FIG. 2, the concrete paving machine  1  is provided with a guide  20  along which the dowel apparatus  17  can be moved. This movement can be obtained by means of conventional driving means, such as pressure cylinders or chain drives or cable drives which, for clarity&#39;s sake, are not represented in the FIGS. 1 and 2. 
     The concrete paving machine  1 , of course, is also provided with means which allow the dowel apparatus  17  concerned to perform a movement perpendicular to the working width of the concrete paving machine  1 , in such a manner that the dowel apparatus  17  can be kept stationary for a certain period of time, whereas the actual concrete paving machine  1  moves further, as well as means which hold the dowel apparatus  17  in its stationary position. 
     According to the invention, the first-mentioned means consist of guides  21  and  22  at which the aforementioned guide  20  is suspended, in such a manner that the guide  20 , together with the dowel apparatus  17  attached thereto, can be kept for a certain period of time on one and the same place according to the direction W, whereas the concrete paving machine  1  is rolling further. 
     According to a particular embodiment of the invention, the means which can hold the dowel apparatus  17  according to the direction W in a stationary position consist of supports  23  formed, for example, of pressure cylinders with elements which are extensible vertically downward, for example, cylinder bars, which can be lowered next to the concrete road  3  onto the ground  24  and/or can be pressed in the ground  24 , in such a manner that the guide  20  and a dowel apparatus  17  suspended thereupon are locked against displacement in the direction W. 
     A more detailed view thereof is represented in FIG. 10 which further is described hereafter. 
     It is noted that the guides  21 - 22 , the guide  20  and the dowel apparatus  17  can be attached dismountable at the frame  4 , in such a manner that, in the transport condition of the concrete paving machine  1 , they can be removed. 
     The use of the dowel apparatus  17  is represented schematically in FIG.  2 . First, this dowel apparatus  17  is placed into a position A 1 , and it is provided with dowels  18 . At the moment when the dowels  18  have to be brought into the concrete  2 , these are set free for the dowel apparatus  17 . Subsequently, the dowel apparatus  17  is brought into the position A 2 , whereas the guide  20  according to the working direction W is held on the same place. Thereafter, in this position A 2 , also a series of dowels  18  is brought into the concrete  2 . 
     Subsequently, the guide  20 , over guides  21  and  22 , can be drawn towards the frame  4 . 
     In the embodiment of FIGS. 1 and 2, the width covered by the dowel apparatus  17  preferably is half of the total working width B. 
     In FIGS. 3 and 4, a variant is represented whereby the concrete paving machine  1 , more particularly, the frame  4  thereof, is extensible according to the working width. 
     A particularity of the embodiment of FIGS. 3 and 4 consists in that the dowel apparatus  17  applied therein extends over a width which is equal to the working width in the slid-together condition of the concrete paving machine  1 . Another particularity herein consists in that the maximum working width of the concrete paving machine  1 , thus, the working width in maximally extended position, is twice the width covered by the dowel apparatus  17 . 
     In this embodiment, the guide  20  preferably shall be extensible, such that the working width can be continuously adapted to the width of the concrete road  3  to be realized. Hereby, it is noted that in the case that the working width is no multiple of the width covered by the dowel apparatus  17 , the two positions into which the dowel apparatus  17  shall be brought shall overlap each other. This, however, does not form a problem in that then it only has to be taken into account that, at the height of the overlapping part, dowels  18  must be provided only once. 
     In the most preferred form of embodiment, the concrete paving machine  1  shall be provided with at least two, and even better precisely two, dowel apparatuses  17  which are movable according to the working width, such as represented in FIGS. 5 and 6. These dowel apparatuses  17  are situated substantially in line next to each other. 
     As represented in FIGS. 5 and 6, the concrete paving machine  1  hereby can be extensible. It is particularly advantageous that in this case the two dowel apparatuses  17 , in the slid-together condition of the concrete paving machine  1 , cover the entire working width B, such as visible in FIG.  5 . 
     The dowel apparatus  17  may be of any construction. Preferably, however, a dowel apparatus  17  shall be applied,. such as described hereafter by means of FIGS. 9 to  17 , which dowel apparatus  17  can be applied in the concrete paving machine  1  from FIG. 5 as well as in the one from the figures preceding it. 
     Hereby, the dowel apparatus  17  substantially consists of, on one hand, a distribution device  25 , which can be positioned above the concrete road  3  to the formed, for the distribution of dowels  18  over the width of the dowel apparatus  17 , as well as for retaining these dowels  18  for a certain period of time in order to be able to deposit them subsequently on the concrete  2 , whereby this distribution device  25  is provided with a movable carriage  26  or slide for the dowels  18  and, on the other hand, a device  27  for vibrating the dowels  18  into the concrete  2 . 
     The distribution device  25  for distributing the dowels  18  and retaining them for a certain period of time consists, as represented in the FIGS. 11 to  16 , of a distribution frame  28  which is provided with recesses  29  in which the dowels  18  can be provided, and shiftable locking means  30  cooperating with this distribution frame  28  which, in locked position, prevent the dowels  18  from dropping through the recesses  29 , and, in unlocked position, provide for that the dowels  18  well can drop through these recesses  29  downward onto the concrete  2 . 
     The distribution frame  28  substantially is made in the form of a framework, with hollow longitudinal members  31 - 32  having an L-shaped profile. Hereby, the aforementioned recesses  29  are provided opposite in the lowermost flanges  33  of the longitudinal members  31 - 32  and form seats in which dowels  18  can be positioned at well-defined distances from each other. 
     The aforementioned locking means  30  substantially are formed of a slide which is movable between at least two positions, a position whereby this slide prevents that the dowels  18  drop off the aforementioned seats, and a position whereby the aforementioned recesses are set free, respectively. As visible in FIGS. 11 to  16 , this slide is formed by two longitudinal members  34 - 35 , in which recesses  36  are provided in the lowermost flanges  37 . Hereby, the longitudinal members  34 - 35  are slidable in the hollow longitudinal members  31 - 32 , in such a manner that, in a first position, the recesses  29  are closed off beneath by means of the flanges  37  and, in a second position, the recesses  36  become situated opposite to the recesses  29 , in such a manner that a free passage is created for the dowels  18  and the latter can drop downward. 
     As clearly visible in the FIGS. 11 and 12, the aforementioned carriage  26  substantially consists of a framework  38  which can be slid over the longitudinal members  31  and  32 , with compartments  39 , separated by partitions  40 , in which each time a dowel  18  can be placed. The compartments  39  are without bottom. 
     It is obvious that driving means are provided to move the carriage  26 . As schematically represented in FIG. 11, to this aim use can be made of cables  41  with which the carriage  26  can be shifted to and fro, for example, by means of a not represented motor. 
     In FIG. 11, also the drive for shifting the locking means  30  between the aforementioned two positions is also represented schematically, which drive consists of a pressure cylinder. 
     The vibration device  27  for vibrating the dowels  18  into the concrete  2  consists of pressing elements  43  which are attached at a frame  44  which, in this case, by means of a parallelogram construction formed by the basic frame  45  of the dowel apparatus  17  and the arms  46 - 47 - 48 , can be moved up and down by means of a pressure cylinder  59 . The vibration effect is obtained by means of vibration motors  49 . In case of possible deviations, the position of the frame  44 , more particularly its being parallel with the concrete road  3  to be formed, can be regulated by means of adjustment elements  50 . 
     In the FIGS. 9 and 10, it is visible that the guide  20  consists of telescopically extensible parts  51  and  52 . The dowel apparatus  17  can be moved along these by means of guiding wheels  53 - 54  which cooperate with rails  55 - 56  which are provided at the parts  51  and  52 , respectively, such that such dowel apparatus  17  can roll over smoothly from one part to the other. 
     As indicated schematically in FIG. 10, the concrete paving machine  1  is provided with driving means for moving the respective dowel apparatuses  17  in function of the work to be performed, which driving means per dowel apparatus  17  consist, for example, of a cable  57  and a motor  58  with which the basic frame  45  can be moved along the guide  20 . 
     Of course, reset means are also provided for placing the guide  20 , together with the dowel apparatuses  17  suspended thereon, back to the starting extremity of the guide  21 - 22 , after the dowels  18  have been vibrated into the concrete  2 . These reset means can, for example, consist of one or several pressure cylinders which are not represented in the figures. 
     According to the invention, the concrete paving machine  1  can be provided with means allowing an independent height adjustment at least at two places, viewed in the direction perpendicular to the working direction. In this manner, it is obtained that the height adjustment of different tools can take place independently. This is important in the first place in concrete paving machines  1  which are relatively long in working direction and can bend relatively far. As a result of the independent height adjustments, each tool concerned then can be precisely adjusted in height, for example, in function of a guideline or similar which is stretched alongside the road, or in function of any other guiding means, such as, for example, a laser beam. 
     In the example of the FIGS. 8 and 9, an independent height adjustment is provided of, on one hand, the dowel apparatuses  17  and, on the other hand, a smoothening beam  60 . 
     Hereby, the distance of the dowel apparatus  17  above the surface to be paved with concrete is regulated by height-adjustment means formed by pressure cylinders  61  at the height of the support elements  5 - 6 - 7 - 8 . The independent height adjustment of the smoothening beam  60  is performed by means of separate pressure cylinders  62  or similar. 
     The working of the concrete paving machine  1  described heretofore can easily be deduced from the figures. 
     Hereby, first the aforementioned slide, formed by the longitudinal profiles  34 - 35 , is placed into the position of FIG.  12 . The carriages  26  are situated at the lateral edges of the concrete paving machine  1  and, for example, are filled manually with the exact number of dowels  18 . Subsequently, these carriages  26  are moved over the longitudinal profiles  31 - 32 , as a result of which, as represented in FIG. 12, precisely one dowel  18  is placed in each pair of opposite recesses  29 , this because these recesses  29  are of such dimensions that only one dowel  18  can take place therein. 
     At that moment when the dowel apparatuses  17  are situated at the place where the dowels  18  have to be vibrated into the concrete  2 , first the locking means  30  are put into working, more particularly, first the supports  23  are lowered, as a result of which the guide  20  remains standing at that location. 
     Subsequently, the slides are moved in such a manner that the recesses  36  are positioned opposite the recesses  29 , as a result of which, as represented in FIGS. 10,  15 , and  16 , the dowels  18  drop onto the concrete  2 . 
     Hereafter, the parallelogram-shaped frame  44  is lowered, whereas the vibrating motors  49  are switched on. Hereby, the pressing elements  43  push the dowels  18  into the concrete, after which the frame  44  can be positioned upward again. 
     Subsequently, this can be repeated on adjacent places by moving the dowel apparatuses  17  step by step. 
     It is obvious that the concrete paving machine  1  is provided with the necessary control means in order to let all driven movements take place automatically, according to the desired cycle. More particularly, these control means will provide for that, first, dowels  18  are vibrated into the concrete  2  in the positions of the dowel apparatuses  17  as represented in FIG. 6, that, subsequently, the dowel apparatuses  17  are moved more inward and dowels  18  there are vibrated into the concrete  2 , and this so on until dowels  18  are provided in the concrete  2  over the entire width of the concrete road  3 . 
     As explained in the introduction, preferably the distance between the frame  28  and the concrete  2  is kept automatically constant by adjusting the height of the dowel apparatus  17 . This adjustment allows that the distance can be kept as small as possible, for example, two centimeters, having the advantage that the distance over which the dowels  18  are dropped is very small, too, so that it can be guaranteed that the dowels  18  still are positioned under the pressing elements  43  at the end of their falling movement. 
     In FIG. 17, a variant of the carriage  26  is represented which allows to provide several dowels  18  on top of each other in each of the compartments  39 , without the dowels  18  getting stuck. This is obtained in that the partitions  40  in this case are formed by rotatably beared elements  63 , such as roller bearings. 
     The present invention is in no way limited to the forms of embodiment described by way of example and represented in the figures, on the contrary may such concrete paving machine be realized in various forms and dimensions without leaving the scope of the invention.