Patent Application
20080298893
1. Field of the Invention
The present invention relates to a vibration plate as recited in the preamble of patent claim 1.
2. Description of the Related Art
Vibration plates for soil compaction have long been known. They consist of a soil contact plate charged by a vibration exciter and a drive that drives the vibration exciter. The drive is allocated to an upper mass, while the vibration exciter and the soil contact plate are regarded as belonging to a lower mass. The upper mass and the lower mass are connected via a spring device so as to be capable of movement relative to one another. This is intended to achieve a vibrational decoupling of the upper mass, in order to protect the drive and the operator guiding the vibration plate at the upper mass.
When repairing roadway surfaces, the operator must take care to make the transition as smooth as possible between the existing asphalt layer and the newly applied asphalt layer that is now to be compressed. For this purpose, the operator attempts to achieve a particularly strong compaction of the fresh asphalt in the transition area. For this purpose, in practice it has turned out to be suitable to tilt the vibration plate, i.e., to position it on an edge of the soil contact plate. This operation is frequently supported by the assistance of a second operator.
The above-described spring device that connects the upper mass to the lower mass is standardly realized in the form of rubber buffers situated between the upper mass and the lower mass. Such rubber buffers permit relative movement between the upper mass and the lower mass in any spatial direction. If, in order to achieve stronger edge compaction operation, the vibration plate is positioned on the edge of its soil contact plate, the soil contact plate, i.e. the lower mass, is then tilted relative to the upper mass. This tilting movement is not prevented by the rubber buffers, and is limited in its extent only by the spring action of the rubber buffers.
In addition, a transverse displacement takes place between the upper mass and the lower mass when the vibration plate is standing on its edge.
The drive energy from the drive (standardly a combustion engine or electric motor) is frequently transmitted via a V-belt drive; i.e. from a V-belt pulley situated on the drive via a V-belt to a V-belt pulley provided on the vibration exciter. If a tilting or transverse displacement occurs between the upper mass and the lower mass, the V-belt pulleys of the drive and vibration exciter are no longer in alignment, causing significant stress on the V-belt running between them, and thus to a reduced life span. This results in more frequent interruptions of vibration work, with the associated costs.
From DE 19 20 985 U, a vibration plate is known in which an elastic motor suspension is provided that is realized by a flexible supporting of the motor. The degrees of freedom of the vibrating motor are limited by a guide that is formed by double connecting rods. The double connecting rods permit only a vertical vibrational motion of the motor.
The object of the present invention is to indicate a vibration plate in which alignment errors between the V-belt pulleys of the upper mass and the lower mass due to tilting or transverse displacements between the upper mass and lower mass can be avoided or reduced.
According to the present invention, this object is achieved by a vibration plate according to claims 1 and 7. Advantageous developments of the present invention are defined in the dependent claims.
A vibration plate according to the present invention is characterized in that in addition to the spring device that connects the upper mass to the lower mass, a stabilizing device is provided for guiding the lower mass in its movement relative to the upper mass.
The stabilizing device thus ensures that the upper mass and the lower mass are capable of assuming only predefined positions relative to one another, determined by the stabilizing device. The stabilizing device is to be constructed such that it permits only relative positions in which the required alignment of the V-belt pulleys and the resulting orientation between the upper mass and lower mass is ensured. In the strictest case, the stabilizing device is constructed as a parallel guide, such that it permits only parallel movement of the upper mass and lower mass relative to one another. In the operating case in which the lower mass is vibrating strongly while the upper mass remains relatively still, the distance then changes between the upper and lower masses, and accordingly also between the associated V-belt pulleys.
Of particular significance for practical use is an advantageous specific embodiment of the present invention in which the stabilizing device does not permit tilting of the upper mass relative to the lower mass. While the spring device that connects the upper mass to the lower mass, in the form of e.g. rubber buffers, enables almost arbitrary tilted positions between the upper and lower mass as a function of the spring constant, the stabilizing device prevents tilting, or significantly reduces the tilt angle. Of course, due to the high acting forces and the tolerances that are accepted in such machines, it cannot be excluded that a tilting between the upper mass and the lower mass may nonetheless occur. However, the tilt angle permitted by the stabilizing device is significantly less than would be the case without the stabilizing device.
Here it is particularly advantageous if the stabilizing device does not permit a tilting of the upper mass relative to the lower mass about an axis oriented in a main direction of travel. This prevents lateral tilting, which occurs in particular when the vibration plate is positioned on a side edge of the soil contact plate. A tilting about an axis transverse to the main direction of travel remains possible, in order to permit a pitching movement (a consequence of the machine's design) between the upper mass and the lower mass, thus avoiding increased stress on the stabilizing device.
Vibration plates capable of forward and backward travel require for their travel movement a horizontal relative movement between the upper mass and the lower mass. This must not be hindered by the stabilizing device. Correspondingly, the connection between the upper mass and the lower mass is to be constructed such that the horizontal and vertical relative movement are permitted.
In addition, or alternatively, in a particularly advantageous specific embodiment of the present invention the stabilizing device is constructed such that it does not permit a lateral offset or lateral displacement of the upper mass relative to the lower mass, transverse to the main direction of travel. In this way, it is also possible to prevent or reduce an alignment error between the V-belt pulleys of the upper mass and lower mass.
Preferably, the stabilizing device has at least one dimensionally stable connecting element that connects the upper mass to the lower mass, the connecting element preferably being attached to the upper and lower mass in jointed an articulated fashion. The connecting element represents a guide or steering device, and ensures that only those relative positions between the upper and lower mass can be assumed that are permitted by the connecting element.
In a particularly advantageous specific embodiment of the present invention, the connecting element is a transverse stabilizer. The transverse stabilizer can have a U-shaped element that is situated essentially horizontally and that is attached to the upper mass and to the lower mass via pivot bearings. Transverse stabilizers are known from automotive technology, and ensure that tilting between the upper mass and the lower mass is reduced or prevented.
The U-shaped element is advantageously fastened to the upper mass and/or to the lower mass via at least one vertical lever, said lever being connected in jointed fashion to the upper or lower mass and to the U-shaped element. As in vehicles, this makes it possible to link the U-shaped element to one side via short vertical levers. Preferably, this linkage will take place via two vertical levers in order to ensure the required stability.
Preferably, the open ends of the U-shaped element are linked either to the upper mass or to the lower mass, while a center part, enclosed by the open ends, of the U-shaped element is correspondingly linked to the lower or upper mass situated opposite. Here, the center part can preferably stand essentially perpendicular to the open ends of the U-shaped element enclosing it. In this way, the transverse stabilizer can be produced easily with low manufacturing costs.
It is particularly advantageous that the open ends of the U-shaped element are oriented essentially in the main direction of travel, and that pivot axes determined by the pivot bearings are oriented transverse to the main travel of direction of the vibration plate. This system ensures that the transverse stabilizer prevents tilting of the upper mass relative to the lower mass about an axis oriented in the main direction of travel.
Alternatively, the open ends of the U-shaped element can also be oriented essentially in a direction transverse to the main direction of travel. Correspondingly, the pivot axes specified by the pivot bearings are oriented in the main direction of travel of the vibrating plate. A pitching movement, as explained above, between the upper and lower mass can then be prevented, said movement occurring as the result of the design of vibration exciters in which at least two imbalance shafts are situated parallel to one another and driven rotationally. Because the imbalance masses borne by the imbalance shafts are not situated in the overall center of gravity of the lower mass, they each cause a moment of rotation about the axis through the center of gravity of the lower mass, resulting in a pitching movement of the soil contact plate.
In this solution, a predominantly horizontal low-force displacement in the direction of travel must be permitted at least at one side (area of linkage of the U-shaped element to the upper or lower mass). This could be achieved e.g. by the jointed linkage using vertical levers. Alternatively, the U-shaped element can be constructed such that its transverse rigidity is low, so that the U-shaped element behaves flexibly in the transverse direction.
In a development of the present invention, two U-shaped elements or transverse stabilizers are provided that are situated essentially at right angles to one another. In this way it is possible both to avoid tilting between the upper and lower mass and to suppress a pitching movement.
In another, particularly advantageous, specific embodiment of the present invention, the connecting element is formed by a connecting rod, in particular a Panhard rod. The Panhard rod is also known from the field of automotive engineering, and ensures guidance between the elements to which it is connected.
The Panhard rod can be linked to the upper mass and to the lower mass via joints at its ends.
Preferably, the connecting rod is situated essentially transverse to the main direction of travel, in order in this way to avoid a transverse displacement between the upper and lower mass. In particular if the connecting rod is sufficiently long, the horizontal movement (transverse displacement, transverse offset) can be kept small due to the fact that the vertical movement between the upper and lower mass is small.
In order to avoid unnecessary constructive height, the connecting rod is preferably situated essentially horizontally. However, it can of course also have a slight inclination relative to the horizontal plane.
In order for the connecting rod to be able to achieve its desired effect, it is advantageous if the pivot axes determined by the pivot bearings are oriented in the main direction of travel.
The pivot bearings can preferably be realized in the form of ball-and-socket bearings in order to achieve a corresponding capacity of angular movement.
The connecting rod should be as long as possible, but its length must be adapted to the available constructive space.
In a particularly advantageous specific embodiment of the present invention, two connecting rods are provided that are situated essentially parallel to one another. In this way, for example one connecting rod can be linked before and one connecting rod can be linked after the vibration exciter of the lower mass.
It was indicated above that the connecting element, i.e. the transverse stabilizer or the connecting rod, should be dimensionally stable. This preferably means that the connecting element is essentially rigid, in order to achieve the desired guiding action. If it is useful, it is possible to provide spring devices at the ends of the connecting element, i.e. at the points of connection to the upper or lower mass, via which spring devices the connecting element is held. For example, the pivot bearings can be constructed in such a way that they have spring characteristics.
The dimensional rigidity should in particular hold relative to an imagined connecting line that runs between the linkage points of the connecting element to the upper mass and to the lower mass.
In another specific embodiment of the present invention, the connecting element is spring-elastic transverse to the imagined connecting line between the linkage points. This means that it will still be dimensionally stable; however, due to its elastic properties, it can permit certain deformations. Because the spring action produces spring forces in the manner selected by the situation of the connecting element, a reduction of the tilt angle or of the transverse offset between the upper mass on the lower mass is likewise achieved.
These and additional advantages and features of the present invention are explained in more detail below on the basis of examples, with the assistance of the accompanying Figures.
At least one of the imbalance shafts in vibration exciter 2 is rotationally driven by the drive in upper mass 3; here a V-belt drive is standardly used to transmit the rotational movement. This drive is however not shown in
Soil contact plate 1 and vibration exciter 2 form essential elements of a lower mass 4. Lower mass 4 is connected to upper mass 3 via rubber buffers 5 that act as a spring device. Due to the spring characteristics of rubber buffers 5, upper mass 3 and lower mass 4 are capable of movement relative to one another in almost any spatial directions. The mobility is limited only by the spring constant of rubber buffers 5 and the acting deflecting force. Rubber buffers 5 have the task of decoupling the intentionally strong vibrations that act on lower mass 4 from upper mass 3, in order to protect the drive housed there, and also to protect the operator guiding the vibration plate on upper mass 3.
Instead of rubber buffers 5, other springs may also be used that enable a vibration decoupling between lower mass 4 and upper mass 3. However, in practice rubber buffers 5 have proven most successful.
In certain operating states, the operator exerts a one-sided, asymmetrical pressure force on upper mass 3 that is oriented toward the soil, in order to achieve an increased edge pressure of soil contact plate 1. However, the one-sided pressing down of upper mass 3 tilts upper mass 3 relative to lower mass 4. This has the result that V-belt pulleys that are provided on the drive of upper mass 3 and on vibration exciter 2 of lower mass 4 in order to form the V-belt drive are no longer in alignment. The V-belt circulating between the V-belt pulleys is twisted, significantly reducing its lifespan.
In order to avoid such a tilting between upper mass 3 and lower mass 4, a transverse stabilizer 6 is provided that is fashioned as a U-shaped element. Open ends 7 of the U-shaped element are connected to lower mass 4, e.g. the housing of vibration exciter 2, via pivot bearings 8, while a center part 9 of the U-shaped element that is enclosed by open ends 7 is fastened to upper mass 3, e.g. to a housing or to a bearer of the drive, via one or to pivot bearings 10. In order to achieve a horizontal orientation of transverse stabilizer 6 as well as a horizontal relative mobility between upper mass 3 and lower mass 4, a vertical lever 11 can be provided on lower mass 4 or on upper mass 3. If necessary, it is also possible to situate a plurality of vertical levers 11 in order to enable stable guidance of transverse stabilizer 6.
Vertical lever or levers 11 are connected in jointed fashion to upper mass 3 via pivot bearings 12. Vertical levers 11 should be short relative to transverse stabilizer 6 in order to prevent larger lever forces from occurring.
Transverse stabilizer 6 is fashioned as a dimensionally rigid connecting element in order to avoid a tilting of upper mass 3 relative to lower mass 4 about an axis oriented in main direction of travel X of the vibration plate. If the operator correspondingly attempts to position soil contact plate 1 of the vibration plate on its lateral edge, the vibration plate as a whole behaves rigidly, so that in particular a tilting of upper mass 3 relative to lower mass 4 is prevented.
Alternatively to the depicted transverse stabilizer 6, a transverse stabilizing effect can also be achieved using one or more rotationally rigid connecting rods or tubes, e.g. rotationally rigid telescoping tubes, if these are attached between upper mass 3 and lower mass 4 in jointed, longitudinally displaceable fashion in the longitudinal direction (main direction of travel X).
Thus, here as well lower mass 4 is essentially formed by soil contact plate 1 and vibration exciter 2, while the drive (not shown) is housed in upper mass 3. Lower mass 4 is decoupled in terms of vibration from lower mass 3 via rubber buffers 5.
In addition, in
As described above, during operation of the vibration plate operating situations occur in which upper mass 3 or lower mass 4 are loaded at one side, i.e. asymmetrically, which disturbs the required alignment of V-belt pulley 15 with the V-belt pulley of the drive, and deflects V-belt 16 out of its running plane. While in connection with
In order to avoid such errors of alignment, two Panhard rods 17 and 18 (connecting rods) are situated in jointed fashion between upper mass 3 and lower mass 4 as stabilizing connecting elements. For the jointed connection, pivot bearings 19 are provided on lower mass 4 and pivot bearings 20 are provided on upper mass 3.
Panhard rods 17, 18 should be as long as possible, so that when there are changes of distance between upper mass 3 and lower mass 4, only slight horizontal displacements (relative to soil contact plate 1 in the horizontal position) occur due to angular changes. In addition, Panhard rods 17, 18 are essentially situated horizontally, as shown in
Panhard rods 17, 18 are situated transverse to main direction of travel X, as can be seen in particular in
Panhard rods 17, 18 stabilize the relative position between upper mass 3 and lower mass 4 in such a way that, in particular when lateral forces are applied, a lateral displacement can be avoided or reduced, so that the V-belt pulleys remain essentially in one plane.
Panhard rods 17, 18 should be as dimensionally rigid as possible in order to perform their guiding function. The linkage of Panhard rods 17, 18 to pivot bearings 19, 20 can also take place via flexible elements such as springs or rubber-metal connections. The relative movement between upper mass 3 and lower mass 4 is within a range that can easily be accommodated by rubber springs.
Alternatively, the entire Panhard rod 17, 18 can also be realized as a spring element, in which case it need not necessarily be fastened to the upper and lower mass via pivot bearings. Rather, the ends of the Panhard rod can also be fixedly connected to the upper and lower mass. Given sufficiently strong dimensioning of the spring-elastic Panhard rod, this rod is able to accommodate vertically oriented transverse forces through elastic deformation, thus permitting a vertical movement of soil contact plate 1 relative to upper mass 3, while transverse forces that are oriented horizontally are introduced axially into Panhard rod 17, 18, so that they do not cause any significant deformation due to the axial rigidity of Panhard rod 17, 18.
Instead of the two Panhard rods 17, 18 shown in
In addition to the specific embodiments of the vibration plate shown in the Figures, further variants are also conceivable. For example, alternatively or in addition to transverse stabilizer 6 from
It is also possible to combine transverse connecting piece 6 with one or more Panhard rods 17, 18. The possible variations are determined by the designer's desire to enable or to prevent or reduce particular relative movements between the upper mass and the lower mass.
With the aid of the stabilizing device, which has at least one connecting element in the form of transverse stabilizer 6 or Panhard rod 17, 18, it is possible to prevent or to reduce undesired relative movements between the upper mass and the lower mass (rolling swaying movement, tilting, lateral displacement), without adversely affecting the vibration isolation of upper mass 3 from lower mass 4.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 058 485.3 | Dec 2005 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2006/011554 | 12/1/2006 | WO | 00 | 8/8/2008 |
