Machine element or mechanism – Mechanical movements – Rotary to or from reciprocating or oscillating
Patent
1989-10-26
1991-04-30
Herrmann, Allan D.
Machine element or mechanism
Mechanical movements
Rotary to or from reciprocating or oscillating
366128, F16H 3302, B01F 1100
Patent
active
050107780
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a vibrator having two axially parallel, interlocking, counterrotating unbalanced shafts, one of which is driven by a drive motor, with the unbalanced shafts, for continuous opposite rotation for altering the phase relationship of eccentrics, being coupled via a hub that is disposed in a rotatable yet axially fixed manner on one of the unbalanced shafts and that in a wall thereof that surrounds the one shaft is provided with a groove that extends along the one shaft and in which slidingly engages a pin that is fixedly secured to the one shaft and that, in a slot of the one shaft that extends therealong and at an angle to the hub groove, is displaceable via an adjustment member that is disposed coaxially in the one shaft and is randomly actuatable via a servomotor.
BACKGROUND OF THE INVENTION
Vibrators of this type are known applicant's U.S. Pat. No. 4,356,736, Franz Riedl, issued Nov. 2, 1982.
Although with the known vibrator the frequency of the excited' oscillation can be varied by changing the speed of the drive motor and the direction of the vector of the directed vibration by shifting the pin relative to the hub groove, the m.r value is prescribed as a constant. It is frequently desired to be able to operate not only with a selectable, prescribed vibration frequency and a selectable, prescribed vibration direction, but also with a selectable, prescribed displacement of the vibration, at least between two different values, of the compaction element that is connected to the vibrator. The displacement "s" of the vibration is a function of the mass M of the compaction element and the mr value of the vibrator pursuant to the equation ##EQU1## where "m" is the vibrationally effective mass of the exciter and "r" is the distance of the center of gravity of this mass from the central axis of the unbalanced shaft.
It is an object of the present invention to provide a vibrator of the aforementioned general type where also the m.r value can be varied between a predetermined minimum value and a predetermined maximum value.
SUMMARY OF THE INVENTION
The aforementioned object is realized by the following: the direction of operation of the driven shaft is reversible; each of the unbalanced shafts has an eccentric part that is fixedly mounted thereon and has an eccentric part that is freely rotatable thereon over a predetermined angular range between extreme positions that are delimited by stop means which, relative to the fixed eccentric part, are disposed in such a way that the entire eccentric, comprised of a fixed eccentric part and the movable eccentric part, in one extreme position of the movable eccentric part has a maximum value and in the other extreme position has a minimum value, with the rotatable eccentric parts on both unbalanced shafts each assuming the same extreme position, which is a function of the direction of operation; and the servomotor is double acting.
With the inventive vibrator, the freely rotatable eccentric parts on the two unbalanced shafts, depending upon the direction of operation thereof, are disposed either respectfully against the one or the other stop, and in particular from unbalanced shaft to unbalanced shaft respectively against stops that correspond with one another for the same m.r value of the individual shafts, so that for a given direction of operation, relative to the directed vibration, a maximum resultant m.r value is obtained and for the other direction of operation a minimum m.r value is obtained, without this having an impact upon the direction of vibration that is selected via the position of the pin relative to the hub groove.
It is also an object of the present invention to embody a vibrator according to the invention in such a way that the double-acting servomotor can be integrated into the vibrator accompanied by a minimum requirement of space. This is achieved in that the double-acting servomotor comprises two single-acting servomotors having opposite directions of operation, with one of the servomotors engaging the adjustment
REFERENCES:
patent: 4356736 (1982-11-01), Riedl
Herrmann Allan D.
Laub David W.
Wacker-Werke GmbH & Co. KG
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