Vibration roller with at least one roll tire and a double shaft

Details Vibration roller with at least one roll tire and a double shaft Vibration roller with at least one roll tire and a double shaft

1997-06-06

1999-08-10

Will, Thomas B.

Road structure, process, or apparatus

Apparatus

Means to agitate material

404122, E01C 1938, E01C 1926

Patent

active

059348240

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a vibration roller with at least one roll tire and a double shaft vibration generator arranged therein wherein the motorically driven unbalance shafts thereof are rotatably supported in a common support contained within the roll tire such that their respective axis of rotation extends parallel to the drive axis of the roll tire.
Vibration rollers of this kind are known from European Patent Application 0 530 546 A1. In these known vibration rollers the two unbalance shafts of the double shaft vibration generator extend parallel to one another on opposite sides of the drive axle of the respective roll tire symmetrically thereto and are rotatably supported in a common generator housing which itself is supported pivotably in a common carrier within the respective roll tire. One of the two unbalance shafts is rotatably driven via gear wheels by a hydraulic drive motor and is coupled with gear wheels to the other drive shaft such that the two unbalance shafts rotate at all times in opposite directions with the same rpm in the generator housing. The flyweights of the two unbalance shafts have the same mass and the same center of gravity spacing so that the vibration generator within the two roll tires produce the same oriented vibration which extends radially to the drive axis of the respective roll tire and the orientation of which depends on the spatial adjustment of the housing of the unbalance shafts.
The solution according to European patent application 0 530 546 A1 is advantageously suitable in connection with soil types which can be compacted best by application of shearing strain and combinations of shearing and compressive strain and it is also well suitable for an economical compaction of relatively great layer thicknesses. Furthermore, a slip produced by the shearing and compressive strain combinations can be counteracted and the traction of the roller can be improved.
The solution according to European Patent Application 0 530 546 A1 has, however, also disadvantages.
In practice, the change of driving orientation takes, especially on bituminous material, approximately 10 to 15 seconds so that for a driving velocity of approximately 5 km/h for the braking process and the subsequent acceleration to 5 km/h in the counter direction a travel distance of 3.5 to 5 m is required. Along this travel distance the vibrator housing is mirror symmetrically adjusted with respect to the vertical plane. This adjustment process causes constantly changing compressive and shearing strain on the soil so that inhomogeneous compaction and undesirable rut formation results. In order to maintain such an inhomogeneous compaction and rut formation within allowable limits, the adjustment process would have to be performed within a fraction of a second which, however, with the known vibration roller is practically not achievable because the vibration generator with respect to the pivot axis has a very large moment of inertia (I=.SIGMA. mr.sup.2) which is caused by the pivotable generator housing itself, by the relatively large distance of the unbalanced shafts from the pivot axis of the generator housing coinciding with the drive axis of the roll tire as well as by the bearing and drive units. For pivoting the generator housing a torque M.sub.d =I* .DELTA.W/.DELTA.t is required. This torque thus increases proportionally with I and the angular acceleration .DELTA.W/.DELTA.t. This means that the shorter the pivoting time is and the greater the moment of inertia I of the generator system, the greater the torque must be. The greater the required torque, the more complicated, however, is the control process.
Furthermore, pivotable generator housings that contain the complete construction of the generator system and the additional pivot bearings require a high technical expenditure and are expensive.
A further disadvantage of the known vibration roller according to European Patent Application 0 530 546 A1 is the unfavorable traction behavior under certain operating conditions.
Durin

REFERENCES:
patent: 4201493 (1980-05-01), Braun
patent: 4454780 (1984-06-01), Goehler et al.
patent: 5248216 (1993-09-01), Vural
patent: 5797699 (1998-08-01), Blancke et al.

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