Claims
- 1. A variable amplitude vibratory apparatus comprising:
- shaft means supported for rotation about an axis;
- first movable weight means mounted eccentrically on said shaft means for rotation therewith for movement between a position of relatively reduced eccentricity and a position of relatively increased eccentricity with respect to the axis of rotation;
- first spring means biasing said first movable weight means toward the position of relatively reduced eccentricity;
- second movable weight means mounted eccentrically on said shaft means for rotation therewith for movement between a position of relatively reduced eccentricity and a position of relatively increased eccentricity with respect to the axis of rotation, said second movable weight means being mounted with its center of mass on the opposite side of said shaft means from the center of mass of said first movable weight means;
- second spring means biasing said second movable weight means toward the position of relatively reduced eccentricity;
- said first spring means being preloaded to retain said first movable weight means in the position of relatively reduced eccentricity so that said shaft means remains balanced until the rotational shaft velocity increases above a first predetermined magnitude whereupon said first movable weight means begins outward movement against the action of said first spring means, the center of mass of said first spring means being positioned substantially on the axis of rotation while said first movable weight means is retained in the position of relatively reduced eccentricity, said first spring means moving toward a first spring means eccentric position with respect to the axis of rotation as said first movable weight means moves outward against the action of said first spring means, the regulated movement of said first movable weight means and said first spring means combining to progressively unbalance said shaft means until maximum unbalance is achieved at a higher, second predetermined magnitude of rotational shaft velocity;
- said second spring means being preloaded to retain said second movable weight means in the position of relatively reduced eccentricity until the rotational shaft velocity increases beyond a higher, third predetermined magnitude whereupon said second movable weight means begins outward movement against the action of said second spring means toward the position of relatively increased eccentricity, the center of mass of said second spring means being positioned substantially on the axis of rotation while said second movable weight means is retained in the position of relatively reduced eccentricity, said second spring means moving toward a second spring means eccentric position with respect to the axis of rotation as said second movable weight means moves outward against the action of said second spring means, the movement of said second movable weight means and said second spring means combining to substantially reduce the unbalance of the shaft means caused by the positioning of said first weight means and first spring means in the position of maximum eccentricity until said shaft is balance at a higher, fourth predetermined magnitude of rotational shaft velocity, said second spring means being selected to define a predetermined range of rotational velocity between the third and fourth predetermined magnitude of rotational shaft velocity so that the amplitude of said apparatus may be selectively varied within the predetermined range;
- first rod means mounted on said shaft means and having a first spring retainer, said first rod means extending substantially perpendicularly to the axis of rotation of said shaft means and slidably supporting said first movable weight means, said first spring means comprising a helical compression spring mounted concentrically about said first rod means and preloaded by said first spring retainer;
- second rod means mounted on said shaft means and having a second spring retainer, said second rod means extending substantially perpendicularly to the axis of rotation of said shaft means and slidably supporting said second movable weight means, said second spring means comprising a helical compression spring mounted concentrically about said second rod means and preloaded by said second spring retainer;
- first stop means for limiting outward movement of said first movable weight means and first spring means;
- second stop means for limiting outward movement of said second movable weight means and second spring means; and
- said shaft means comprising enclosing structure extending between two end plates containing said first and second movable weight means and said first and second spring means therein and having first and second apertures for passage of the respective movable weight means, said first and second movable weight means comprising elongate hollow members, said first and second spring means being contained within the fist and second movable weight means, said first and second rod means extending from the enclosing structure into the first and second movable weight means, said first and second spring means being compressed between the interior of the first and second movable weight means and the first and second spring retainers, respectively.
- 2. A variable amplitude vibratory apparatus comprising:
- shaft means;
- means supporting said shaft means for rotation about an axis;
- first movable weight means mounted eccentrically on said shaft means for rotation therewith for movement between a position of relatively reduced eccentricity and a position of relatively increased eccentricity with respect to the axis of rotation;
- first spring means biasing said first movable weight means toward the position of relatively reduced eccentricity, the center of mass of said first spring means being positioned substantially on the axis of rotation while said first movable weight means is in the position of relatively reduced eccentricity;
- second movable weight means mounted eccentrically on said shaft means for rotation therewith for movement between a position of relatively reduced eccentricity and a position of relatively increased eccentricity with respect to the axis of rotation;
- second spring means biasing said second movable weight means toward the position of relatively reduced eccentricity, the center of mass of said second spring means being positioned substantially on the axis of rotation while said second movable weight means is in the position of relatively reduced eccentricity;
- said first spring means being preloaded to retain said first movable weight means in the position of relatively reduced eccentricity so that the shaft means remains balanced until the rotational shaft velocity increases above a first predetermined magnitude whereupon said first movable weight means begins outward movement against the action of said first spring means toward the position of relatively increased eccentricity and said first spring means begins movement toward a position of eccentricity with respect to the axis of rotation to progressively unbalance said shaft means as rotational shaft velocity further increases until said shaft means is substantially unbalanced at a higher, second predetermined magnitude;
- said second spring means being preloaded to retain said second movable weight means in the position of relatively reduced eccentricity until the rotational shaft velocity increases beyond a higher, third predetermined magnitude whereupon said second movable weight means begins outward movement against the action of said second spring means toward the position of relatively increased eccentricity and said second spring means begins movement toward a position of eccentricity with respect to the axis of rotation to substantially reduce the unbalance of the shaft means at a higher, fourth predetermined magnitude of rotational shaft velocity caused by the positioning of the first weight means and first spring means in the position of substantially increased eccentricity, said second spring means being selected to define a predetermined range of rotational velocity between the third and fourth predetermined magnitude of rotational shaft velocity so that the amplitude of said apparatus may be selectively varied within the predetermined range; and
- said first and second spring means comprising spring means secured between said shaft means and said first and second movable weight means, respectively, thereby performing the combined function of supporting said first and second movable weight means and biasing said first and second movable weight means toward the positions of relatively reduced eccentricity, said first and second spring means thereby forming first and second combined support/spring means; and
- said shaft means comprising enclosing structure extending between two spaced end plates, said enclosing structure containing said first and second combined support/spring means therein and having first and second apertures therein for passage of the respective movable weight means, said first and second combined support/spring means being positioned concentrically about a substantial portion of the respective movable weight means, a first end of said first and second combined support/spring means being secured to said shaft means about the periphery of the respective apertures and a second end being secured to the respective movable weight means and abutting said enclosing structure to preload said first and second spring means.
- 3. The variable amplitude vibratory apparatus of claim 2 further including first and second stop means mounted on said shaft means for limiting outward movement of the respective movable weight means.
- 4. The variable amplitude vibratory apparatus of claim 2 wherein said first and second combined support/spring means include elastomeric members.
- 5. The variable amplitude vibratory apparatus of claim 2 wherein said first and second combined support/spring means comprise helical compression spring members.
- 6. A balanced variable amplitude vibratory apparatus comprising:
- shaft means supported for rotation about an axis;
- first movable weight means mounted eccentrically on said shaft means for rotation therewith;
- first combined support/spring means for supporting said first movable weight means or movement between a position of relatively reduced eccentricity and a position of relatively increased eccentricity with respect to the axis of rotation and for baising said first movable weight means toward the position of relatively reduced eccentricity; second movable weight means mounted eccentrically on said shaft means for rotation therewith, the center of mass of said second movable weight means bein mounted on the opposite side of said shaft means relative to the center of mass of said first movable weight means;
- second combined support/spring means for supporting said second movable weight means for movement between a position of relatively reduced eccentricity and a position of relatively increased eccentricity with respect to the axis of rotation and for biasing said second movable weight means toward the position of relatively reduced eccentricity;
- said first combined support/spring means being preloaded to retain said first movable weight means in the position of relatively reduced eccentricity so that said shaft means remains balanced until the rotational shaft velocity increases above a first predetermined magnitude whereupon said first movable weight means begins outward movement against the action of and while supported by said first combined support/spring means, the center of mass of said first combined support/spring means being positioned substantially on the axis of rotation while said first movable weight means is in the position of relatively reduced eccentricity, said first combined support/spring means moving to a position of eccentricity with respect to the axis of rotation as said first movable weight means moves outwardly against the action of said first combined support/spring means, the movement of said first combined support/spring means and said first movable weight means combining to progressively unbalance said shaft means as rotational shaft velocity further increases until said shaft means is substantially unbalanced at a higher, second predetermined magnitude; and PG,63
- said second combined support/spring means being preloaded to retain said second movable weight means in the position of relatively reduced eccentricity until the rotational shaft velocity increases beyond a higher, third predetermined magnitude whereupon said second movable weight means begins outward movement against the action of and while supported by said second combined support/spring means toward the position of increased eccentricity, the center of mass of said second combined support/spring means being positioned substantially on the axis of rotation while said second movable weight means is retained in the position of relatively reduced eccentricity, said second combined support/spring means moving to a position of eccentricity with respect to the axis of rotation as said second movable weight means moves against the action of said second combined support/spring means, the movement of said second combined support/spring means and said second movable weight means combining to substantially reduce the unbalance of the shaft means at a higher, fourth predetermined magnitude of rotational shaft velocity caused by the positioning of said first movable weight means in the position of substantially increased eccentricity and the positioning of the first combined support/spring means in the position of eccentricity, said second combined support/spring means being selected to define a predetermined range of rotational velocity between the third and fourth predetermined magnitude of rotational shaft velocities so that the amplitude of said apparatus may be selectively varied within the predetermined range;
- the shaft means comprising enclosing structure extending between two spaced end plates, said enclosing structure containing said first and second combined support/spring means therein and having first and second apertures therein for passage of the respective movable weight means, said first and second combined support/spring means being positioned concentrically about a substantial portion of the respective movable weight means and secured at a first end to said shaft means about the periphery of the respective apertures and at a second end to the respective movable weight means and abutting said enclosing structure to preload the respective combined support/spring means.
- 7. The balanced variable amplitude vibratory apparatus of claim 6 further including first and second stop means mounted on said shaft means for limiting outward movement of the respective movable weight means.
- 8. The balanced variable amplitude vibratory apparatus of claim 6 wherein the first and second combined support/spring means include elastomeric members.
- 9. The balanced variable amplitude vibratory apparatus of claim 6 wherein the first and second combined support/spring means comprise helical compression spring members.
- 10. A balanced variable amplitude vibratory apparatus comprising:
- shaft means supported for rotation about an axis;
- first movable weight means mounted eccentrically on said shaft means for rotation therewith;
- first combined support/spring means for supporting said first movable weight means for movement between a position of relatively reduced eccentricity and a position of relatively increased eccentricity with respect to the axis of rotation, and for biasing said first movable weight means toward the position of relatively reduced eccentricity;
- second movable weight means mounted eccentrically on said shaft means for rotation therewith, the center of mass of the second movable weight means being mounted on the opposite side of said shaft means relative to the center of mass of said first movable weight means;
- second combined support/spring means for supporting said second movable weight means for movement between a position of relatively reduced eccentricity and a position of relatively increased eccentricity with respect to the axis of rotation, and for biasing said second movable weight means toward the position of relatively reduced eccentricity;
- said first combined support/spring means being preloaded to retain said first movable weight means in the position of relatively reduced eccentricity so that said shaft means remains balanced until the rotational shaft velocity increases above a first predetermined magnitude whereupon said first movable weight means begins outward movement against the action of and while supported by said first combined support/spring means, the center of mass of said first combined support/spring means being positioned substantially on the axis of rotation while said first movable weight means is in the position of relatively reduced eccentricity, said first combined support/spring means moving to a position of eccentricity with respect to the axis of rotation as said first movable weight means moves outwardly against the action of said first combined support/spring means, the movement of said first combined support/spring means and said first movable weight means combining to progressively unbalance said shaft means until maximum unbalance is achieved at a higher, second rotational shaft velocity;
- said second combined support/spring means retaining said second movable weight means in the position of relatively reduced eccentricity until the rotational shaft velocity increases beyond a higher, third predetermined magnitude whereupon said second movable weight means begins outward movement against the action of and while supported by said second combined support/spring means toward the position of increased eccentricity, the center of mass of said second combined support/spring means being positioned substantially on the axis of rotation while said second movable weight means is retained in the position of relatively reduced eccentricity, said second combined support/spring means moving to a position of eccentricity with respect to the axis of rotation as said second movable weight means moves outwardly against the action of said second combined support/spring means, the movement of said second combined support/spring means and said second movable weight means combining to substantially reduce the unbalance of said shaft means caused by the positioning of said first movable weight means in the position of substantially increased eccentricity and the positioning of said first combined support/spring means in the position of eccentricity until a higher, fourth predetermined magnitude is achieved whereupon the shaft means is again balanced, said second combined support/spring means being selected to define a predetermined range of rotational velocity between the third and fourth predetermined magnitude of rotational shaft velocity so that the amplitude of said apparatus may be selectively varied within the predetermined range;
- first and second stop means mounted on said shaft means for limiting outward movement of the respective movable weight means;
- said shaft means comprising enclosing structure extending between two spaced end plates, said enclosing structure containing said first and second combined support/spring means therein and having first and second apertures therein for passage of the respective movable weight means as said movable weight means move outwardly; and
- said first and second combined support/spring means secured between the periphery of said first and second apertures in said enclosing structure and said first and second movable weight means, respectively, said first and second combined support/spring means being positioned concentrically about a substantial portion of said first and second weight means and abutting against said enclosing structure to preload the combined support/spring means.
- 11. The balanced variable amplitude vibratory apparatus of claim 10 wherein said first and second combined support/spring means include elastomeric members.
- 12. The balanced variable amplitude vibratory apparatus of claim 10 wherein said first and second combined support/spring means comprise helical compression spring members.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of co-pending application Ser. No. 06/068,343, filed Aug. 21, 1979.
This invention relates to variable amplitude vibratory apparatus, and more particularly to rotational type vibration generating mechanism wherein the vibrational amplitude is a function of rotational velocity.
At the present time, various vibrational devices are in commercial use. These include conveyors, shaker screens, pile drivers, pavement breakers, asphalt finishers, cement spreaders, concrete vibrators, grain crushers, and similar mechanisms. One particular type of vibratory device is a vibratory roller/compactor wherein vibration is utilized in addition to the usual rolling action to effect compaction of the underlying material. In many instances it is considered desirable to vary the vibrational amplitude of such apparatus in order to increase versatility and thereby render the apparatus more useful. For example, in the case of a vibratory roller/compactor it is considered desirable to maintain a large vibrational amplitude when the device is operating at lower vibrational speeds in order to compact coarse materials in deep lifts, and to reduce the vibrational amplitude when the device is operating at higher (rotating) vibrational speeds and working in thin lifts on finely graded material such as asphalt so as not to crush and destroy the material being compacted.
Heretofore changes in vibrational amplitude have typically comprised dual amplitude or multiple amplitude devices. That is, such devices have been capable of vibrating at two or more specific amplitudes, but have not been capable of operating over an infinitely variable range of amplitudes. Thus, a need exists for a variable amplitude vibratory apparatus wherein the vibrational amplitude can be varied over a range, and wherein the vibrational amplitude can be selected to provide the most efficient operation.
Other variable amplitude devices have been developed and are in use in vibratory/roller compactors. However, these devices require elaborate control systems for the transfer of fluids and gases and the restriction of speeds through elaborate electrical controls when the fluid displacement is at a maximum. Thus, the need exists for a variable amplitude vibratory apparatus that does not require special controls or liquid or gas connections to the inside of the drum, and that does not require elaborate electrical controls to limit the vibrational speed.
The present invention comprises a variable amplitude vibratory apparatus which overcomes the foregoing and other disadvantages long since associated with the prior art. In accordance with the broader aspects of the invention, a shaft is mounted for rotation about an axis. The shaft is eccentrically weighted so as to effect vibration upon rotation. Additional weight structure is mounted on the shaft for movement radially outwardly against spring action in response to a centrifugal force caused by rotation of the shaft. At a predetermined rotational velocity the force on the weight overcomes the holding power of the spring. Because of this movement the balance of the shaft is changed, and the vibrational amplitude of the apparatus therefore varies as a function of the rotational velocity of the shaft. The amplitude of the apparatus is simply controlled within predetermined limits by controlling the speed of the shaft.
Various embodiments of the invention are disclosed. Each embodiment can be used in any application where forced vibration performs useful work. In accordance with one embodiment, a single movable weight structure is utilized. The movable weight structure is slidably supported on rods which are secured to the shaft. The rods secure springs which are selected so as to prevent movement of the movable weight structure until the rotational velocity of the shaft reaches a predetermined magnitude. Thereafter the movable weight structure slides outwardly on the rods against the action of the springs, with the positioning of movable weight structure on the rods being dependent on the rotational velocity of the shaft. As the movable weight structure moves outwardly, the vibrational amplitude caused by shaft rotation is progressively diminished.
In accordance with a second embodiment of the invention, dual movable weight structures are utilized. The shaft is initially balanced. This feature allows smoother acceleration of the shaft and is advantageous in a vibratory roller/compactor when the shaft is being slowed to a stop, so as to eliminate a vibrating frequency that would cause resonance in the adjacent and/or supporting structure. The first movable weight structure is counterbalanced, and is mounted for movement outwardly relative to the axis of rotation of the shaft against spring action when the rotational velocity of the shaft reaches a first predetermined magnitude. At this point, the vibrational amplitude of the apparatus is maximized. The second movable weight structure is in turn adapted to begin sliding movement outwardly relative to the axis of rotation of the shaft against spring action when the rotational velocity of the shaft reaches a second, higher magnitude. Outward movement of the second movable weight structure functions to diminish vibrational amplitude as the rotational velocity of the shaft increases. The rotational velocity of the shaft may subsequently be increased further to rebalance the shaft.
A third embodiment of the invention utilizes leaf springs to resist outward movement of a weight in response to shaft rotation. Dual leaf spring/weight structures may be utilized in order to provide an apparatus that is balanced at low rotational velocities, that is substantially unbalanced when the rotational velocity of the shaft reaches a first predetermined magnitude, and that is unbalanced to a lesser degree when the rotational velocity of the shaft reaches a second, higher predetermined magnitude.
A fourth embodiment of the invention utilizes torsional springs to resist outward movement of weights in response to shaft rotation. Two pairs of torsional spring/weight structures are mounted for pivotal movement about axes perpendicular to the axis of rotation of the shaft. The apparatus is balanced at low rotational shaft velocities, up to a first predetermined magnitude, but thereafter becomes progressively unbalanced as the rotational shaft velocity reaches a second, higher predetermined magnitude.
In accordance with a fifth embodiment of the invention, multiple movable weight structures are utilized so that the shaft is initially balanced. This feature allows smoother acceleration of the shaft and is also advantageous in a vibratory roller/compactor as the shaft is brought to a stop without causing resonance in the drum/frame system. The shaft remains balanced up to a first predetermined shaft rotational velocity, at which point the primary movable weight structure(s) commences outward movement relative to the axis of rotation of the shaft against spring action. At a second predetermined rotational shaft velocity, the primary movable weight structure reaches maximum outward displacement, whereby the vibrational amplitude of the apparatus is maximized. Outward movement of the secondary movable weight structure(s) functions to diminish vibrational amplitude as the rotational shaft velocity increases beyond a third predetermined magnitude. Thus, the vibrational amplitude of the apparatus may be changed by increasing or decreasing rotational velocity of the shaft.
A sixth embodiment of the invention incorporates triple movable weight structures and is initially balanced. Dual pivotal weight structures pivot outwardly from the shaft in opposition to elastomeric springs after a first predetermined rotational shaft velocity has been attained. The vibrational amplitude of the apparatus is maximized until the rotational velocity of the shaft reaches a second higher value, when outward movement of the secondary movable weight structure(s) functions to decrease vibrational amplitude as the rotational shaft velocity increases further.
In accordance with a seventh embodiment of the invention, dual movable weight structures are utilized so that the shaft is initially balanced. The first movable weight structure is mounted for movement outwardly relative to the axis of rotation of the shaft against stacks of elastomeric springs until the rotational shaft velocity reaches a first predetermined magnitude, which corresponds to maximum vibrational amplitude of the apparatus. The second movable weight structure in turn begins outward movement relative to the axis of rotation of the shaft against stacks of elastomeric springs when the rotational shaft velocity reaches a second predetermined magnitude. This functions to decrease vibrational amplitude of the apparatus as the rotational shaft velocity increases.
According to an eighth embodiment of the invention, dual movable weight structures are enclosed within a housing on a shaft so as to be initially balanced. Elastomeric springs are utilized to resist outward movement of the weights in response to shaft rotation. The shaft is balanced until rotational shaft velocity reaches a first predetermined value, at which point the first movable weight structure begins outward movement relative to the axis of rotation of the shaft until reaching a maximum displacement corresponding to maximum vibrational amplitude. At a second, higher predetermined shaft rotational velocity, the second movable weight structure begins outward movement which tends to counterbalance the first movable weight, decreasing vibrational amplitude as the rotational shaft velocity increases. After the second movable weight structure reaches maximum displacement, the vibrational amplitude stays constant in spite of further increases in rotational shaft velocity. In each of the foregoing embodiments, other spring systems, including elastomeric springs, coil springs, and disc springs, may be utilized interchangeably to resist weight movement, if desired.
The ninth embodiment of the invention features dual movable weight structures constructed of a resilient material so as to resist deflection thereof. The weight structure is enclosed within a housing mounted on a shaft which is balanced. The dual, combination spring/weight structures are responsive to rotational shaft velocity to provide an apparatus that is balanced at relatively low rotational velocity, that is substantially unbalanced when the rotational shaft velocity reaches a first predetermined magnitude, and that is unbalanced to a lesser extent when the rotational shaft velocity reaches a second, higher predetermined magnitude.
In the tenth embodiment of the invention, dual movable weight structures are utilized with the shaft being initially balanced. The movable weight structures are slidably supported on rods which are secured to the shaft. The rods secure helical compression springs which are pre-loaded so as to prevent movement of a movable weight structure until the rotational velocity of the shaft reaches a predetermined magnitude. The center of mass of the shaft remains coincident with the axis of rotation of the shaft until a first predetermined shaft rotational velocity is achieved, at which point the primary movable weight structure(s) commences outward movement relative to the axis of rotation of the shaft against the spring action. As the primary movable weight structure(s) move outwardly, the springs acting on the primary movable weight structure(s) are compressed and the center of mass of the springs also move in the outward direction thereby enhancing the eccenricity of the shaft. At a second predetermined rotational shaft velocity, the primary movable weight structure(s) reaches a maximum outward displacement, whereby the vibrational amplitude of the apparatus is maximized. Outward movement of the secondary movable weight structure(s) functions to diminish vibrational amplitude as the rotational shaft velocity increases beyond a third predetermined magnitude. The springs acting on the secondary movable weight structure(s) are compressed as the secondary movable weight structure(s) move outwardly and the center of mass of the springs also move in the outward direction to further diminish the vibrational amplitude of the rotational shaft. Thus, the vibrational amplitude of the apparatus may be changed by increasing or decreasing rotational velocity of the shaft. The springs acting on the secondary movable weight structure(s) are chosen to allow a selective variation of vibrational amplitude in the range of shaft velocity between the third predetermined magnitude and a fourth predetermined magnitude where the secondary movable weight structure(s) reaches maximum outward displacement whereby the shaft is balanced. A condition of balanced rotation may be achieved either at rotational velocity below the first predetermined rotational shaft velocity or above the fourth predetermined magnitude wherein the secondary movable weight structure(s) reaches maximum outward displacement whereby the shaft is again balanced.
According to an eleventh embodiment of the invention, dual movable weight structure(s) are secured by a combined support/spring means on a shaft, with the entire structure being initially balanced. The combined support/spring means are preloaded to prevent movement of a movable weight structure(s) until the rotational velocity of the shaft reaches a predetermined magnitude. At a first predetermined magnitude, the primary movable weight structure(s) commences outward movement relative to the axis of rotation of the shaft against the spring action. As the primary movable weight structure(s) moves outwardly, the combined support/spring means is compressed and the center of mass of the support/spring means also moves outwardly to supplement the eccentricity of the primary movable weight structure(s). At a second predetermined rotational shaft velocity, the primary movable weight structure reaches maximum outward displacement whereby the vibrational amplitude of the apparatus is maximized. Outward movement of the secondary movable weight structure(s) functions to diminish vibrational amplitude as the rotational shaft velocity increases beyond a third predetermined magnitude. The combined support/spring means supporting the secondary movable weight structure(s) is also compressed and its center of mass moves outwardly to further diminish the vibrational amplitude of the rotational shaft. At a fourth predetermined rotational shaft velocity, the secondary movable weight structure also reaches maximum outward displacement whereby the vibrational apparatus is again balanced. The combined support/spring means supporting the secondary movable weight structure(s) is chosen to permit selective variation of vibrational amplitude in the range of shaft velocity between the third and fourth predetermined magnitudes.
In a twelfth embodiment of the invention, multiple movable weight structure(s) are utilized with elastomeric spring means which pre-load the weight structure(s) so that the shaft has a center of mass coincident with the axis of rotation and is initially balanced up to a first predetermined shaft rotational velocity. At the first predetermined shaft rotational velocity, the primary movable weight structure(s) commences outward movement relative to the axis of rotation of the shaft against the spring action. At a second predetermined rotational shaft velocity, the primary movable weight structure(s) reaches maximum outward displacement, whereby the vibrational amplitude of the apparatus is maximized. Outward movement of the secondary movable weight structure(s) functions to diminish vibrational amplitude as rotational shaft velocity increases beyond a third predetermined magnitude. At a fourth predetermined rotational magnitude, the secondary movable weight structure(s) reaches maximum outward displacement, whereby the vibrational apparatus is again balanced. The elastomeric spring means resisting outward movement of the secondary movable weight structure(s) is chosen to permit selective variation of vibratory amplitude in a range of shaft velocity between the third and fourth predetermined magnitudes.
US Referenced Citations (18)
Foreign Referenced Citations (2)
| Number |
Date |
Country |
| 187489 |
Jan 1956 |
ATX |
| 385061 |
Apr 1908 |
FRX |
Continuation in Parts (1)
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Number |
Date |
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| Parent |
68343 |
Aug 1979 |
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Patent Grant
4348912
