Abstract:
A paving machine arranged to spread and level concrete along a path. The paving machine has a frame assembly, and at least one concrete processing device carried by the frame assembly. The processing device include at least two mutually screed elements spanning the width of the frame assembly and are mutually adjustable in height relative to the frame assembly. The paving machine futher include a control device that positions the at least two screed elements relative to the frame assembly.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a paving machine, more particularly a machine for spreading and levelling concrete, as well as to a method for forming a concrete path. 
     As known, such paving machines are used for forming a variety of concrete pavings, in the first place for forming concrete roadways, but, furthermore, also for forming large concrete floors and such. 
     It is known that such paving machines mostly consist of a movable frame at which one or more processing devices for processing the concrete are fixed or can be fixed. Mostly, use is made of several processing devices providing for different processings, such as spreading the concrete, which has been poured in front of the device, in width, vibrating the concrete, drawing the concrete into a shape, providing dowels in the concrete, smoothing the concrete by means of a smoothing beam and finishing by means of a smoothing board moving to and fro. 
     It is also known that such paving machines, including the processing devices, can be made extensible in order to be able to adjust the working width. An example thereof is known from the international patent application WO 95/28525. In such case, the frame as well as the processing devices are telescopically extensible, whereby the processing devices then consist of several parts which telescope either in each other or along each other or at a distance behind each other. 
     Such paving machines, the processing devices of which consist of several parts which together must span the working width, and especially paving machines with parts which, as aforementioned, are extensible in respect to each other, show the disadvantage that the mutual position of the parts of one and the same processing device may change during paving, as a result of sagging under the weight of the paving machine and/or as a result of the pushing in upward direction, when, centrally below the paving machine, a surplus of concrete is poured. This has as a consequence that the surface of the formed concrete path deviates from the desired shape. It has already been proposed to remedy this by using manually turnable screw jacks with which the mutual position of the aforementioned parts can be adjusted. This solution, however, has the disadvantage that it is less efficient, as in practice an adjustment exclusively will be carried out when major, visually discernible deviations occur. 
     Further, it is also known that paving machines can be equipped with oscillating finishing beams for assisting in smoothing the concrete of the path surface. An example thereof is described in U.S. Pat. No. 5,941,659, in which two finishing beams, situated at a distance from each other according to the direction of movement, are applied, i.e. one finishing beam performing a substantially vertical oscillation, and a finishing beam performing a substantially horizontal oscillation. The vertical oscillation has as a purpose, so to speak, to tamper the gravel in the concrete into the surface, whereas the horizontal oscillation additionally smoothes the concrete at the surface. In that hereby use is made of two oscillating finishing beams cooperating with one and the same path surface, such embodiment, however, shows the disadvantage that the average positions which are taken by these finishing beams in respect to the formed path surface, have to be precisely coordinated in mutual respect, and that, with certain deviations, malfunctions in the faultless working may occur. Another disadvantage consists in that two separately driven systems, one behind the other, are necessary, as a result of which the total length of the paving machine, seen according to the paving direction, is influenced in a disadvantageous manner. 
     The present invention aims at a paving machine, whereby various improvements are intended which contribute to a better quality of the obtained concrete path and/or which allow for performing a more efficient control of the quality of the realized concrete path. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention, a paving machine is aimed at, with one or more processing devices consisting of two or more parts which together span the working width, whereby a solution is offered for efficiently excluding or minimizing deviations in the surface of the concrete path which arise as a consequence of undesired alterations in the mutual position of such parts. More particularly, according to this first aspect, it is aimed at excluding or at least minimizing undesired deviations as a result of the sagging of the paving machine and/or the pushing-up of parts thereof. 
     According to this first aspect, the invention thus relates to a paving machine, comprising a movable frame with at least one processing device for processing the concrete which extends according to the working width and which consists of at least two parts,or otherwise called screed elements, which possibly are movable in respect to each other, in order to adjust the span of the processing device, with as a characteristic that the paving machine comprises means, or otherwise called a control device, on one hand, directly or indirectly, control the mutual position of said parts, such in respect to the surface to be formed, as well as, on the other hand, allow for adjusting the mutual position in function of said control. 
     By providing the paving machine with means which, on one hand, allow for such control and, on the other hand, allow for an adjustment, a very precise follow-up of the mutual position of said parts is possible, and it is possible to rapidly take measures in order to remedy any undesired alteration in the position by means of a corresponding adjustment. 
     Preferably, said means consist of detection means or otherwise called a detection device, performing observations in respect to said mutual position, as well as controllable adjustment means, or otherwise called an adjustable device, for commanding said parts in such a manner that a desired adjustment is realized. More particularly, it is preferred that the controllable adjustment means are coupled to the detection means, such that an adjustment is performed in function of a desired adjustment of the mutual position. Thereby, an automatic feedback is provided for, whereby the operator of the paving machine himself no longer has to perform any adjustments. 
     Although the invention allows to counteract a variety of deviations between the positions of the respective parts of a processing device, it is clear that said means, in the first place, are intended to control the sagging, pushing-up, respectively, of the processing device. 
     In a practical form of embodiment, the frame of the paving machine, as usual, comprises two side parts carried by movable support elements, and according to the present invention, said means are configured such that they provide for a control in respect to a reference line, reference plane, respectively, which connects the two side parts. In practice, paving machines in fact are kept at a well-defined height at these side parts, for example, by means of sensors which command the height of the side parts in function of pre-set level lines. In the proximity of the side parts, the obtained concrete path thus always is at the right height, and lines or planes connecting the two side parts therefore ideally may serve as a reference line or plane for performing said control. 
     In the case that use is made of such reference line or such reference plane, said parts, at their outwardly directed extremities, are connected to the side parts preferably at a well-defined height, whereas with their inwardly directed extremities, they can be adjusted in height by means of said controllable adjustment means. When the paving machine is realized in a classical manner, with a central basic frame and with side parts provided on frame parts which are extensible in respect to the basic frame, it is preferred that the controllable adjustment means are situated between the basic frame and said two parts of the processing device. As a result thereof, said parts can be easily drawn upward, pushed downward, respectively, in the middle of the span. 
     According to an important preferred form of embodiment, said means comprise detection means which are formed by, on one hand, at least one cable stretched over the width of the paving machine and, on the other hand, one or more sensors cooperating with said cable and said parts of the processing device, which deliver signals in function of the difference in height between said cable and said parts. By a cable, hereby any form of stretchable flexible element has to be understood, thus, also a rope, ribbon or such. Such cable has the advantage that it forms a stable reference line which can hardly be disturbed, on the basis of which line said detection can be performed. 
     In the case that the paving machine comprises one or more processing devices with two or more parts which are movable in respect to each other, in order to adjust the span of the processing device, processing devices, respectively, said means preferably will comprise separately controllable adjustment means per processing device and/or per part of such processing device. In this manner, the position of each processing device, and still more particularly each part thereof, can be adjusted separately, as a result of which any form of deviation can be excluded. 
     However, this does not exclude that according to a variant, a common detection, for example, in a central point, can be provided for, and possibly also an adjustment by means of adjustment means which are common for several processing devices and/or parts thereof. 
     In the case that several separately controllable adjustment means for different processing devices or parts thereof are used, the paving machine preferably comprises several cable lengths stretched over the width of the paving machine, substantially at the height of the respective parts to be controlled of the processing device, processing devices, respectively, which cooperate with respective sensors. In this manner, at different locations an efficient control can be provided. 
     Hereby, it is particularly useful that the respective cable lengths then form part of a single continuous cable which is stretched several times over the width of the paving machine, with the advantage that only one set of means for tensioning the cable is necessary, which means, for example, consist of at least one winding system for winding the cable at least at one end, and/or of at least one elastic tensioning means, or otherwise called an elastic tensioning device, such as a tension spring. 
     The aforementioned device proves its usefulness especially in combination with the form elements and smoothing beams usually applied with paving machines. These, in fact, are heavyweight items, the respective parts of which easily become displaced in respect to each other, especially if they are telescopic. 
     Said controllable adjustment means may be of different kind, however, for practical reasons, it is preferred that pressure cylinders are applied to this end. It is clear that said means can be provided at new paving machines as well as at already existing paving machines, or that new paving machines can be equipped with elements which allow the attachment of such means. Of course, the invention thus relates to all these cases. Taking this into account, the invention thus also relates to a paving machine comprising a movable frame with at least one processing device for processing the concrete, which latter device extends according to the working width and which consists of at least two parts which are movable in mutual respect in order to adjust the span of the processing device, with the characteristic that the paving machine comprises controllable adjustment means with which the mutual position of said parts, such in respect to the surface to be formed, can be adjusted. 
     According to a second aspect of the invention, which either may or may not be combined with the first aspect, an improved embodiment of a paving machine is intended which is provided with one and more oscillating finishing beams, whereby said disadvantages of the known embodiments are excluded or at least are minimized. 
     To this aim, the invention, according to this second aspect, relates to a paving machine for forming a concrete path, whereby this paving machine comprises at least one oscillating finishing beam, with the characteristic that it comprises drive means which allow the finishing beam to perform an upward and a sideward oscillation at the same time. It is clear that thereby at least several of said disadvantages of using two separate finishing beams, oscillating upward and sideward, respectively, are excluded. 
     It also became clear that by the combination of an upward oscillation and sideward oscillation at one and the same finishing beam, anyhow a better smoothing effect is obtained. 
     Preferably, the drive means for the oscillating finishing beam consist of at least two excenter mechanisms providing for the respective oscillations. 
     In the most preferred form of embodiment, the paving machine, according to its direction of movement during paving, will comprise exclusively one oscillating finishing beam, with the exception of possible overlapping portions when several finishing beams, whether telescopically adjustable or not, are active over the working width. 
     Preferably, the finishing beam is mounted at a smoothing beam, more particularly attached in front of such smoothing beam. 
     According to a particular form of embodiment, the finishing beam forms part of a paving machine which is adjustable, more particularly extensible, in the direction of the working width, and does this beam consist of several mutually displaceable parts, whether situated at a distance from each other or not, and us each part equipped with its own driving means for delivering the upward and sideward oscillations. 
     According to a third aspect of the invention, a paving machine is aimed at whereby at all times an efficient control of the concrete of the formed concrete path and/or of the shape of the concrete path can be performed. Up to the present, basically a control only can be performed by afterwards measuring the realized concrete path and/or taking samples by means of drilling. Such samples can only be taken after a sufficient hardening of the concrete in order to perform measurements thereon, as a result of which one mostly has to wait approximately two months before such samples can be taken and tested. According to the third aspect of the invention, an efficient control can be realized in a completely different manner. 
     Thus, according to the aforementioned third aspect, the invention relates to a paving machine for forming a concrete path, with as a characteristic that it is provided with registration means which at least register data relating to the formed concrete path. By means of these registration means, thus, controllable parameters are obtained, from which the quality and other characteristics of the formed concrete path can be derived. 
     Preferably, it comprises registration means registering at least one or more of the following parameters: 
     the width adjustment of the paving machine, more particularly of the working width; 
     the forward speed of the paving machine or of a value representative therefor; 
     the covered distance; 
     the oscillation speed of vibrating means, such as vibrating needles, for vibrating the concrete; 
     the thickness of the concrete path, possibly derived from other parameters; 
     when a concrete path is poured having a roof-shaped profile, the inclination of the roof-shaped profile; 
     the consumed quantity of concrete. 
     In the most preferred form of embodiment, at least two parameters are registered, on one hand, a parameter directly or indirectly related to the speed of the paving machine during paving, and, on the other hand, a parameter directly or indirectly related to the drive of the vibrating means for vibrating the concrete. The connection between these two parameters in fact forms a strong indication for the quality of the concrete. Possibly, this connection also may be formulated in a value, which value then has to be within well-defined limits. It is well-known that, in order to still enable a further paving of the path when the concrete is too wet or too dry, one may locally vibrate the concrete to a major or minor degree, as a result of which it is actually possible to continue working, but this mostly results in a diminishing quality of the concrete. By now following, by means of the registration means, the ratio between the parameters of vibrating and the parameters of the speed of forward movement, it will be automatically known whether the concrete will fulfill the quality requirements or not. 
     By means of said registration means, it is also possible to know where the most critical concrete parts are situated, where then possibly additional controls, by means of taking concrete samples, can be performed. 
     By means of the registration means, it can also be followed up whether a sufficient quantity of concrete per length unit has been applied and/or whether the realized concrete path thus also has a sufficient thickness. 
     The registered data can be registered in different manners, preferably in function of time and/or in function of the covered distance. For instance, the registration may take place by representing the data on a strip of paper, whether in the shape of curves or not, and/or by electronically storing these data, after which they can be visualized on a monitor and/or can be printed. 
     According to another variant, these data automatically will be transmitted to a central unit or a control authority, possibly still during the operation of the concrete paving machine, for example, by means of a wireless connection, for example, a telephone connection, more particularly by means of a cellular phone system or such. 
     According to a fourth aspect, the invention also relates to a paving machine for forming a concrete path, with as a characteristic that it is provided with a computer system with a monitor upon which one or more of the following data can be visualized: 
     the width adjustment of the paving machine; 
     when a concrete path is produced having a roof-shaped profile, in other words, with a surface sloping from the middle towards both lateral edges, data related to the shape of the pre-determined roof-shaped profile; 
     the forward speed of the paving machine; 
     the covered distance; 
     the oscillation speed of applied vibration means for vibrating the concrete; 
     the thickness of the concrete path, possibly calculated from other data, whether put-in or not; 
     when the paving machine is provided with a dowel apparatus, the adjustment of the distance where dowels and/or joints are provided; 
     the visualization of alarm functions; 
     an indication as the dowel apparatus approaches the end of its travel course. 
     By means of this computer system, the operator, in a centralized manner, has different data available, as a result of which an efficient validation of the operation of the paving machine and/or of the obtained result is possible. 
     It is clear that at random a combination can be made of the first and/or the second and/or the third and/or the fourth aspects of the invention. 
     Further, the invention, as mentioned in the aforegoing, also relates to a method for forming a concrete path, with as a characteristic that for forming it, a paving machine is used showing one or more of the characteristics described heretofore, whereby during forming the concrete path, a regulation of the mutual position of said parts of at least one processing device is provided for, and/or a treatment of the concrete surface is performed by means of a finishing beam which simultaneously performs an oscillating movement in upward and sideward directions, and/or a registration, as aforementioned, takes place, and/or a visualization of data by means of a computer system takes place. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     With the intention of better showing the characteristics of the invention, hereafter, as an example without any limitative character, several preferred forms of embodiment are described, with reference to the accompanying drawings, wherein: 
     FIG. 1 in plan view schematically represents a paving machine according to the invention which applies the first aspect of the invention; 
     FIG. 2 represents a view according to arrow F 2  in FIG. 1; 
     FIG. 3 schematically represents an embodiment of a concrete path; 
     FIG. 4 represents a cross-section according to line IV—IV in FIG. 1, whereby an oscillating finishing beam is represented which is realized in accordance with the second aspect of the invention; 
     FIG. 5, at a smaller scale, represents a cross-section according to line V—V in FIG.  4 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     As represented in FIGS. 1 and 2, the invention relates to a paving machine  1 . In the represented example, this machine substantially consists of a movable frame with, on one hand, a basic frame  2 , on which a not-represented driver&#39;s cabin can be provided, and, on the other hand, side parts  3 - 4  which can be laterally displaced by means of frame parts  5  which are extensible in respect to the basic frame  2 , whereby these side parts  3 - 4  are carried by support elements  6 - 7 - 8 - 9 , which rest on the ground in a movable manner and which can be moved on, for example, by means of driven crawler wheels  10 . 
     The support elements  6 - 7 - 8 - 9  comprise height adjustment means, such as vertical adjustment cylinders which allow to maintain the side parts  3 - 4  during moving at a permanent height, such by means of sensors  11  provided to monitor the concrete path  13  to be formed. 
     At the side parts  3 - 4  and below the basic frame  6 , different processing devices  14  for the concrete  15  are attached, whereof, by way of example, only two are schematically represented,  16 ,  17 , respectively. The processing device  16  functions as a form piece at which vibrating needles  18  or similar are attached. The processing device  17  substantially consists of a smoothing beam  19  and, for example, also comprises an oscillating finishing beam  20 , as represented in FIG.  4 . 
     The processing devices  16  and  17  each consist of two mutually opposed parts, or otherwise called screed elements,  21 - 22  and  23 - 24 , respectively, which can be shifted along each other and can be adjusted in function of the working width. Next to the outwardly situated extremities, the parts  21  and  23  are fixedly or hingeably connected to the side part  3 , whereas, at their inwardly directed extremities, they are suspended at the basic frame  2 , as will be described in the following. In the proximity of the outwardly situated extremities, the parts  23  and  24  are fixedly or hingeably connected to the side part  4 , whereas, with their inwardly directed extremities, they also are suspended at the basic frame  2 . 
     In that the whole unit, on one hand, is extensible and therefore, there are plays present in the connections, and, on the other hand, such paving machine  1  mostly is applied for large working widths, it is obvious that the whole easily may sag or also may be pushed upward when centrally too large a mass of concrete is situated below the paving machine  1 . 
     The invention offers a solution to this in that the paving machine  1  is provided with a control device or means which, on one hand, directly or indirectly controls the mutual position of the parts, on one hand,  21  and  22 , and/or, on the other hand,  23  and  24 , in respect to the concrete path&#39;s  13  surface to be formed, as well as, on the other hand, allow to adjust the mutual position in function of the thus obtained control. 
     The aforementioned means are formed by a detection device  25  performing observations in respect to said mutual position, as well as a controllable adjustment device  26  for commanding the parts  21 - 22  and/or  23 - 24  in such a manner that a desired adjustment is realized. 
     In the represented example, the detection device  25  includes sensors  27  provided at the parts  21 - 22 - 23 - 24 , in the proximity of the inwardly directed extremities thereof, which sensors  27  cooperate with cable elements of cable system stretched between the side parts  3 - 4 , which cable element in this case are formed of a single continuous cable  28 , whereby the cable elements of the cable system function as reference lines. These sensors  27  are realized such that they deliver signals in function of the height position which the inwardly directed extremities of the parts  21 - 22 - 23 - 24  take in respect to the cable length extending alongside thereof. 
     These sensors  27  can be of different kind, however, preferably sensors of the same type as the sensors  12  will be applied. Hereby, they may be sensors which exclusively detect whether there is a deviation in one or the other direction, as well as sensors which do not only deliver signals in function of the direction of the deviation, but also in function of the amplitude thereof. 
     The cable  28  is stretched, by means of guiding rolls  29 , to and fro between the side parts  3  and  4 . the tensioning is performed by a tensioning device which, in this case, includes a winding system  30  for winding the cable  28  at one end, and of a tensioning spring  31  with which the other end is attached to a fixed point, in this case to the side part  3 . 
     In the represented example, the controllable adjustment device  26  is situated between the basic frame  2  and the inwardly directed extremities of the parts  21 - 22 - 23 - 24  and includes pressure cylinders  32 , in this case respectively a separate pressure cylinder  32  per part  21 - 22 - 23 - 24 . 
     The controllable adjustment device  26  is coupled to the detection device  25 , such that there is an automatic control. The coupling is performed by means of one or more appropriate control units  33 . Such control unit may consist, in its most simple form, of a hydraulic valve which is controlled in three positions, to wit a closed position, a position whereby pressure is applied to the pertaining pressure cylinder, and a position whereby pressure is reduced. 
     The functioning of the paving machine  1 , more particularly of said control, can easily be deduced from the aforegoing and from the drawings. 
     When manufacturing a flat concrete path  13 , the detection device  25  is adjusted such, or such control by means of the control units  33  is provided for that the parts  21  and  22  remain parallel with their undersides, as well as the parts  23  and  24  remain parallel in respect to each other. With a deviation which indicates a sagging, the pressure cylinders are commanded such that the respective parts  21  and/or  22  and/or  23  and/of  24  are drawn upward at their inwardly directed extremity. With a pushing up, on the other hand, a downwardly directed pressure force will be realized, such that more weight of the paving machine  1  rests on the inwardly directed extremities. 
     It is obvious that by means of the invention, it is not only possible to achieve that the parts  21 - 22  and  23 - 24  mutually are situated in the same plane, but that also different adjustments can be realized, for example, for realizing, as schematically represented in FIG. 3, a concrete path  13  having a roof-shaped profile, with a well-defined slope. In this way, it is also possible to create a concrete path  13  which slopes exclusively in one direction. 
     Although the example solely represents an embodiment whereby only two parts  21 - 22 , as well as  23 - 24 , are present over the working width, it is obvious that it also can be applied with paving machines with several such parts adjacent to each other. Also, the invention can not only be applied with extensible paving machines, but also with a variety of other paving machines comprising parts which, under the influence of different factors, may take undesired deviating positions in respect to each other. 
     The controllable adjustment device  26  may be common for two parts pertaining to one another, for example,  21  and  22 , or also  23  and  24 , for example, when these are coupled to each other at their inwardly directed extremities. 
     Further, each control operation does not have to take place directly by means of a pertaining sensor  27 . So, for example, may the sensor  27  of the part  21  provide for the control of the pertaining pressure cylinder, whereas the control of the pressure cylinder pertaining to part  22  also is performed by means of the sensor  27  placed upon part  21  or by a separate height adjustment, whereby the height of the free extremity of part  22  automatically is adjusted to the height of the free extremity of the part  21 . 
     It is obvious that in the case of an extensible paving machine  1 , of course steps must be taken in order to achieve that the inwardly directed extremities of the parts  21 - 22 - 23 - 24 , for example, are movably coupled to the controllable adjustment device  26 , for example, in a manner such as schematically indicated in FIG. 4, whereby the piston rod  34  of the respective pressure cylinder, by means of a slide  35 , is seated, in a movable manner, in a guiding element  36  provided on the part situated therebelow. 
     In FIGS. 4 and 5, the second aspect of the invention is illustrated, to wit the fact that the paving machine  1  is provided with an oscillating finishing beam  20  which can perform an upward and a sideward oscillation at the same time. To this aim, it is driven by means of two excenter mechanisms  37  and  38  which respectively provide for the movements for the upward and sideward oscillations. 
     The excenter mechanism  37  is driven by a motor  39  and consists of an excenter  40  provided on the shaft of this motor  39 , which excenter, by means of a rod  41 , is hingeably connected to a lever  42  which is fixedly attached to a shaft  43 , such that the shaft  43 , during the rotation of the excenter  40 , is turned to and fro in an oscillating manner. To this shaft  43 , two arms  44  are fixedly attached, at which the finishing beam  20  is suspended by means of coupling parts  45 . 
     The excenter mechanism  38  is driven by a motor  46  and consists of an excenter  47  provided on the shaft of this motor  46 , which excenter, by means of a rod  48 ; is hingeably connected to the finishing beam  20 , by means of a coupling flange  49  provided thereupon in a fixed manner. 
     The shaft  43  is fixedly positioned in support points  44 . 
     The functioning of the finishing beam  20 , more particularly the oscillating drive thereof, can easily be derived from FIGS. 4 and 5. By means of the motor  39  and by the excenter  40 , the shaft  43  is driven in a to-and-fro oscillating manner. This results in an up-and-down-going movement of the coupling parts  45  and, thus, of the finishing beam  20 . At the same time, this finishing beam  20  is moved to and fro by means of the motor  46 , the excenter  47  and the crankshaft  48 , such that a combined movement is created. 
     It is obvious that different oscillation speeds can be applied, whereby these possibly may be adjustable. Also, different oscillation speeds and/or oscillation amplitudes for the sideward and upward movements can be applied, depending on the desired effect. 
     FIGS. 1 and 4 also show that the finishing beam  20  may consist of two parts, which are provided at the parts  23  and  24 , respectively. 
     It is obvious that, in order to realize the third aspect described in the introduction, the necessary sensors and such will be provided at the different parts of the paving machine  1  in order to enable that the parameters to be registered or data which are necessary for determining the parameters to be registered, can be observed. Also, such parameters can be deduced from control operations. So, for example, frequency-controlled motors can be used for the vibration needles  18  which mostly have excenters driven by means of motors, such that the oscillation frequency of the vibration needles  18  immediately can be derived from the control values of the frequency control. 
     In a similar manner, values can be collected and observed in order to feed the computer system mentioned in the introduction. 
     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 paving machine, as well as the aforementioned method, be realized according to various variants while still remaining within the scope of the invention.