Abstract:
A compactor for compacting soil which can be controlled by hand using a bow-shaped control element or similar element. The compactor has a compacting or ramming working mass which is driven by a combustion engine back and forth, linearly, by a crank mechanism and a spring assembly. The compactor is also supported on the ground by a single-axle dolly.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Related Art 
     The invention relates to a tamping appliance for ground compaction, capable of being manually guided by means of a guide fork or the like and having a tamping or beating working mass driven linearly back and forth by an internal combustion engine via a crank mechanism and a spring assembly. 
     2. Discussion of the Related Art 
     Tamping appliances of this type, which are supported on the ground solely by means of the tamping butt, are guided in the desired direction by an operator as a result of the direct transmission of guiding forces by means of a guide fork, or, for example, a drawbar, during the oscillating movement of the tamping butt. When the drive is switched off, the appliance is difficult to transport, and it has to be carried or moved by means of a suitable device, such as, for example, a handcart. 
     On account of manual operation, the weight of such appliances is restricted, and therefore, for example, equipping them with relatively heavy diesel engines creates difficulties. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     The object on which the innovation is based is to design a tamping appliance of the type initially mentioned, in such a way that handling becomes substantially easier, in particular the physical strength required for guiding it is reduced and it is possible, at any time, to change the location of the tamper in a simple way, when it is switched off, without any auxiliary devices. 
     This object is achieved in that the tamping appliance is additionally supported against the ground via an at least single-axle traveling gear 
     By means of the traveling gear, the tamper can easily be moved without additional aids, even when the tamper drive is switched off. When the tamper is in operation, the guiding forces required are appreciably reduced on account of the rolling support of substantial weight components of the appliance. Moreover, there is the possibility of increasing the overall weight of the tamper beyond the limit hitherto considered acceptable and, for example, to provide the tamper with a heavy diesel engine. 
     A highly advantageous embodiment provides for the additional traveling gear to carry the internal combustion engine. 
     In another highly advantageous embodiment, the traveling gear is provided with its own drive, a common power source preferably being provided for generating the tamping movement and for driving the traveling gear. The traveling gear&#39;s own drive may advantageously be designed as a hydraulic drive or take place via a driving chain. The traveling gear drive can expediently be changed over between forward motion and reverse motion. 
     In order to ensure that the tamper, when switched off, is always in a stable position, the traveling gear may advantageously be designed as a three-point traveling gear by means of an additional supporting wheel on that side of the tamping butt which faces away from the driveable axle. 
     In order to keep as low as possible any wear of the traveling gear under the influence of the vibrations which are generated by the tamper and pass through the traveling gear, it is highly advantageous to stabilize the tamper upper mass connected to the traveling gear, that is to say to keep the movement of said upper mass as low as possible while the tamper is in operation. 
     Known manually guided tamping appliances are designed in such a way that the upper mass comprises approximately two thirds and the beating working mass or lower mass one third of the entire tamper mass, whilst the excursions covered in each case by the upper mass and the working mass are in inverse proportion to one another. Here, the upper mass moves in the order of magnitude of 25 to 30 mm. 
     This movement of the upper mass at a frequency of 10-11 Hz has many adverse effects, not only because these vibrations are transmitted to the body of the person guiding the working appliance via a guide fork, in particular to the hand and arm, but also because high loads are exerted on the mounted drive engine, irrespective of its design and, likewise, irrespective of the traveling gear which is provided according to the invention. 
     The output of the tamping system is largely dependent on the upper mass, since too large a working mass or too high a speed of the working mass moves the upper mass overdimensionally and aggravates the problems described above. 
     Although these harmful effects could, in part, be limited by a substantial increase in the upper mass, this would greatly increase the overall weight of the tamper, thus not only raising the power requirement of the drive engine, but also nullifying the benefit achieved by the traveling gear in making it easier to operate the tamper. 
     In order to stabilize the upper mass, without an appreciable increase in the weight of the appliance, and thereby lengthen its life, further improve its handling and protect the operator more effectively against the harmful effects of the vibrations, in a particularly advantageous embodiment of the appliance according to the invention the latter is provided, in the region of the upper mass, with a countermass capable of being driven by the engine jointly with the working mass, but in the opposite direction to the movement of the working mass. 
     The upper mass is pressed upward by a crank mechanism self-supported on its case at the moment when said crank mechanism, via its connecting rod, a guide piston and a spring assembly, presses the working mass, and consequently the tamping butt, downward. The result of the spring assembly is that, during the downward movement of the guide piston, first these springs are tensioned, at the same time absorbing energy, whereupon, with a delay induced thereby, they subsequently release the stored energy again for the downward movement of the tamping butt. This delay must be taken into account when the movement of the countermass is coordinated with the movement of the working mass. When the working mass is drawn upward again by the crankpin of the crank mechanism, the upper mass is moved downward. 
     For this purpose, in an advantageous embodiment, the drive of the countermass is derived from the crank mechanism, and the movement of the spring assembly end connected to the crank mechanism and the movement of the countermass are offset relative to one another with respect to the crank angle, by 180° minus a phase shift derived from the design parameters of the spring assembly. 
     When the spring assembly end connected to the crank mechanism exceeds the lower end point of its linear movement, the energy stored until then in the spring assembly is released as tamping or beating energy, so that only at this moment is the countermovement of the countermass required in order to damp the movement of the upper mass, or, in other words: the movement of the countermass to top dead center is to take place only when the spring assembly end connected to the crank mechanism has already reached bottom dead center. This is achieved by means of the above-described phase shift which, in practice, must be coordinated at least approximately with the design parameters. 
     According to an expedient embodiment, the countermass is guided on the upper mass in parallel with the direction of movement of the working mass. At the same time, in an advantageous embodiment, the countermass is driven by a compensating eccentric on the crank mechanism, specifically, for example, via a connecting rod. According to another expedient embodiment, the connection between the countermass and the compensating eccentric may be designed as a slider crank. 
     According to another expedient variant, the countermass consists of two part masses arranged in each case on one side of the crank mechanism or the other, at approximately the same height with respect to the axis of rotation of the crank mechanism, and each part mass is driven by an eccentric pin on an eccentric disk assigned to said part mass and rotatably coupled to the crank mechanism, the connection between the eccentric pin and the associated part mass being designed in each case as a slider crank. 
     In another advantageous variant, the countermass consists of unbalanced masses which are mounted on the upper mass rotatably about mutually parallel axes and are driven in rotation in opposite directions by the crank mechanism and of which the flywheel moment and mutual phase relationship are arranged in such a way that they generate a vibration directed in counteraction to the working mass, whilst, in another embodiment, the countermass consists of two centrifugal weights which are arranged next to one another, symmetrically to the direction of movement of the working mass, at approximately the same height in this direction, and which are directly coupled to one another rotatably in opposite directions and are driven by the crank mechanism. 
     In another expedient embodiment for the avoidance of lateral forces, the countermass consists of a first centrifugal weight seated directly on the shaft of the crank mechanism and of two second centrifugal weights of the same flywheel moment, which are arranged next to one another, symmetrically to the direction of movement of the working mass, at approximately the same height in this direction, and which are driven rotatably in the opposite direction to the first centrifugal weight by the crank mechanism and the flywheel moment of which is in each case approximately half as great as that of the flywheel moment of the first centrifugal weight. 
     In yet another variant, the countermass consists of a first centrifugal weight seated directly on the axis of rotation of the crank mechanism and of a second centrifugal weight which is arranged behind said first centrifugal weight and has approximately the same flywheel moment as the latter and is driven in the opposite direction to the first centrifugal weight about an axis of rotation somewhat offset relative to the axis of rotation of the crank mechanism in parallel with the direction of movement of the working mass. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The innovation is explained in more detail with reference to the following description of its exemplary embodiments illustrated in the drawing in which: 
     FIG. 1 shows a side view of a tamper designed according to the innovation, with a hydraulic drive of the single-axle traveling gear, 
     FIG. 2 shows a view from the right of the appliance shown in FIG. 1, 
     FIG. 3 shows a side view, similar to that of FIG. 1, of a tamper with a chain drive of the traveling gear and with an additional supporting wheel, 
     FIG. 4 shows a view from the right of the appliance shown in FIG. 3, 
     FIG. 5 shows a sectional view of a first embodiment of the crank mechanism for generating the tamping movement, with a countermass, as seen transversely to the crank axis and partially in section along a plane containing the crank axis, 
     FIG. 6 shows a detailed section through the case of the crank mechanism of the embodiment shown in FIG. 5, in a plane at right angles to the crank axis, 
     FIG. 7 shows a view, similar to that of FIG. 5, according to a second embodiment, 
     FIG. 8 shows a sectional view, similar to that of FIG. 6, of the second embodiment, 
     FIG. 9 shows a sectional view, similar to that of FIG. 8, in the case of a third embodiment, 
     FIG. 10 shows a sectional view, similar to that of FIG. 8, in the case of a fourth embodiment, 
     FIG. 11 shows a sectional view, similar to that of FIG. 8, in the case of a fifth embodiment, 
     FIG. 12 shows a view, similar to that of FIG. 7, according to a sixth embodiment, and 
     FIG. 13 shows a sectional view, similar to that of FIG. 8, of the second embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The tamping appliance designed according to the innovation is illustrated in a first embodiment, designated as a whole by  100   a , in FIGS. 1 and 2 and in a second embodiment, designated as a whole by  100   b , in FIGS. 3 and 4, the tamping implement, conventionally guided manually via a guide fork or a drawbar, being designated as  110   a  and  110   b  respectively. The tamping implement  110   a  is connected, via parallel links  112  and  114 , to a single-axle traveling gear  116   a  having two wheels  118  and  120 , the shaft of which does not exceed the width of the tamping butt  12  of the tamping implement  110   a.    
     In the variant according to FIGS. 3 and 4, the tamping implement  110   b  is connected approximately rigidly to the traveling gear  116   b , that is to say only slight relative movement becomes possible between the tamping implement  110   b  and the traveling gear  116   b  by means of elastic damping members  124  and  126  which are to counteract the transmission of vibrations to the traveling gear  116   b . Another conspicuous difference is that the traveling gear  116   b  is supplemented by a third supporting wheel  128  so as to form a three-point traveling gear, in order to improve the stability, particularly when the tamping implement  110   b  is switched off. This third supporting wheel  128  is carried by an arm  130  mounted on the crankcase  14  of the tamping implement  110   b.    
     Mounted on the traveling gear  116   a  or  116   b  is the guide fork  132  which is otherwise connected directly to the tamping implement  110   a  or  110   b.    
     A crank mechanism arranged in the crankcase  14  of the tamping implement  110   a  or  110   b  serves for actuating the tamping butt  12 , said crank mechanism being explained in more detail with reference to FIGS. 5 to  13 . For driving the crank mechanism, the tamping appliance  100   a  or  100   b  is provided with an internal combustion engine  135  which is carried by the traveling gear  116   a  or  116   b  and is arranged in the region  134 . 
     In the embodiment according to FIGS. 1 and 2, it is possible to have an oscillating movement with relatively large angular deflection between the tamping implement  110   a  and the traveling gear  116   a . This appliance  100   a  is therefore equipped with a hydraulic drive which comprises a hydraulic pressure source connected to the engine, not shown, in the region  134 . A hydraulic motor  136  for actuating the crank mechanism is mounted on the crankcase  14  and is connected to the pressure source via supply lines  138 . Supply lines  140  lead, in the region of the traveling gear  116   a , to a hydraulic drive  142  of the traveling gear wheels. 
     In the case of the relatively low movement between the tamping implement  110   b  and the traveling gear  116   b  a direct drive connection may be provided between the internal combustion engine arranged in the region  134  and the crank mechanism arranged in the crankcase  14 , only slight compensation of the axial offset being necessary, which does not present any difficulties to the average person skilled in the art. A hydraulic drive may therefore be dispensed with and a chain mechanism  144  be provided for driving the wheels. 
     The tamping implement  110   a  or  110   b  consists, in dynamic terms, of a working mass  11  which is connected to the tamping butt  12  and which is connected, via a spring assembly  13  concealed by a concertina-like cladding portion  18 , to a crank mechanism mounted in the so-called upper mass which is represented in FIGS. 1 to  4  by the crankcase  14 . Oscillation is built up between the upper mass and working mass by means of the crank mechanism. In order to improve the handling and life of the appliance, the movement of the upper mass should be kept as low as possible. The measures described below with reference to FIGS. 5 to  13  serve this purpose. 
     As shown in FIG. 5, the crank mechanism is supplied with drive energy via a motor output shaft  22  provided with a toothed pinion  24  which is in engagement with a crank disk  26 . The crank disk  26  carries two crankpins  28  and  30  offset at approximately 18° (FIG.  6 ). The crank pin  28  is connected, via a yokelike connecting rod  32  surrounding the output shaft  22 , to a guide piston  34  which is arranged, moveably in the direction of the axis  16 , in a piston guide  36  connected to the crankcase  14  and, being concealed in FIG. 5 by the concertina-like portion  18 , is connected to the tamping butt  12  via the spring assembly. Connected to the crankpin  30  via a connecting rod  38  is a piston  40  which is likewise arranged, moveably in the direction of the axis  16 , in a piston guide  42  and which, together with the connecting rod  38 , forms a countermass to the working mass. 
     FIG. 6 shows an angular distance of 180° between the crankpins  28  and  30 . The piston or the countermass  40  would thereby reach top dead center when the guide piston  34  connected to the spring assembly  13  (FIGS. 1 and 3) reaches its bottom dead center. For the reasons already described, however, the piston  40  is to reach top dead center with a time delay, depending on design features of the spring assembly, and because of this the angular distance must be selected smaller than 180° by the amount of a particular phase shift angle. In practice, this phase shift angle may be 50-70°. 
     In the variant illustrated in FIGS. 7 and 8, the crank disk  26   1  which is engagement with the toothed pinion  24   1  on the output shaft  22   1  is provided with a crank  29  bent to form the crank pins  28   1  and  30   1  the crankpin  28 which forms the free end of the crank  29  engaging into a sliding block  31  arranged displaceably in a guide slot  33  which is formed in a piston  40   1  serving as a countermass. The piston  40   1  is guided, so as to be moveable parallel to the axis of movement  16 , in a guide  42   1  formed on the crankcase  14   1 . Mounted on the crankpin  28   1  is the connecting rod  32   1  for connection to the guide piston (not shown) which serves for transmitting movement to the spring assembly. The functioning of this variant largely corresponds to the design according to FIGS. 5 and 6, but, by the countermass being driven by a slider-crank mechanism, makes it possible to have a design which is shortened in the direction of the axis of movement  16 . 
     FIG. 9 shows a variant which likewise provides a slider crank drive for the countermass, the arrangement making further shortening possible. The crank disk  26   2  provided with the crankpin  28   2  for the connecting rod  32   2  for the transmission of movement to the spring assembly is connected fixedly in terms of rotation to a gearwheel  35  which is arranged coaxially to said crank disk and with which two circumferentially toothed eccentric disks  37  and  39  are in engagement on both sides of the axis of movement  16  and at the same height with respect to the latter. The eccentric disks carry in each case an eccentric pin  30   a   2  or  30   b   2  which engage into guide slots  33   a   2  and  33   b   2 , assigned to them, of two identically designed pistons  40   a   2  and  40   b   2  which together form the countermass and which are mounted, so as to be displaceable parallel to the axis of movement, in guides  42   a   2  and  42   b   2  assigned to them and formed on the crankcase  14   2.    
     The following variants replace the linearly moveable countermass by rotating unbalanced masses. 
     In the variant according to FIG. 10, a gearwheel  35   3  is connected fixedly in terms of rotation and coaxially to the crank disk  26   3  for actuating the connecting rod  32   3 . Two toothed disks  37   3  and  39   3  of equal size and of the same number of teeth, which are in engagement with one another and which are provided in each case with a centrifugal weight  41  and  43 , are arranged on both sides of the axis of movement  16  and are the same distance from this and the same height with respect to the latter. The toothed disk  37   3  is connected fixedly in terms of rotation and coaxially to a gearwheel  45  which is in engagement with the gearwheel  35   3  of the same number of teeth, so that the two centrifugal weights  41  and  43  move in opposition, in a predetermined phase relationship, to the movement of the connecting rod  32   3 . At the same time, the centrifugal weights  41  and  43  are arranged in such a way that their positions are in each case located opposite one another mirror-symmetrically to the axis of movement  16 . As a result, both lateral forces, such as are caused by the oblique connecting rod  38  in the embodiments according to FIGS. 5 and 6, and frictional losses in the guides  33 ,  33   a   2  and  33   b   2  according to FIGS. 7 to  9 , are avoided. 
     The variant according to FIG. 11 shows an unbalanced mass acting in only one direction and located on the crank mechanism and two unbalanced masses which are in opposition thereto and which ensure mass compensation and therefore also prevent any lateral movement. The unbalanced mass on the crank mechanism is illustrated by the centrifugal weight  47  on the crank disk  26   4 . Two disks  37   4  and  39   4 , corresponding in diameter to the crank disk  26   4  and provided with centrifugal weights  41   4  and  43   4 , are arranged symmetrically to the axis of movement. The three disks  26   4 ,  37   4  and  39   4  are connected for joint movement by means of a non-slip gear connection, for example a chain  51 , in such a way that the two disks  37   4  and  39   4  move in the same direction of rotation, but in opposition to the crank disk  26   4 . 
     FIGS. 12 and 13 show a last variant which is a development of the variant according to FIG. 11 in as much as the two disks  37   4  and  39   4  rotating in the same direction are now replaced by a single disk  53  which is offset relative to the crank disk  26   5  in the direction of the output shaft  22   5  and which is driven via its own pinion  55  and an intermediate wheel  57  in opposition to the crank disk  26   5  by the output shaft  22   5  and is provided with a centrifugal weight  59 .