Road structure – process – or apparatus – Apparatus – Means to agitate material
Reexamination Certificate
1999-04-19
2001-05-01
Lillis, Eileen D. (Department: 3673)
Road structure, process, or apparatus
Apparatus
Means to agitate material
C404S122000, C404S133050, C074S061000, C074S087000
Reexamination Certificate
active
06224293
ABSTRACT:
FIELD OF THE PRESENT INVENTION
The present invention relates to a vibration generator for a compaction machine and, in particular, to a variable amplitude vibration generator for a compaction machine used in the road construction industry.
BACKGROUND OF THE PRESENT INVENTION
It is well known to use a compaction machine having a compaction drum in leveling a road surface in the road construction industry. Furthermore, it is also well known that better results and better efficiency are achieved by causing small high-frequency vibrations in the compaction drum during such leveling. Vibrations are often generated by rotating an eccentric weight within the compaction drum. Moreover, the amplitude of vibration is dependent upon the rotational rate of the eccentric weight; however, the amplitude of vibration is also dependent upon the radial spacing of the center of mass of the weight to the axis of rotation, i.e., the eccentricity of the weight.
In Schmelzer et al. U.S. Pat. No. 4,830,534 (the '534 Patent), vibrations in the compaction drum are generated by rotation of an eccentric weight mounted on a rotor shaft. A high amplitude of vibration or, alternatively, a low amplitude of vibration is produced depending upon the radial position of the eccentric weight with regard to the axis of rotation of the shaft. Springs are provided in the mounting of the eccentric weight and, when the eccentric weight is not undergoing rotation, the springs urge the eccentric weight into a default radial position in abutment with the shaft. A latch fixedly mounted to the shaft controls the radial positioning of the eccentric weight as well as drives the rotation of the eccentric weight. In particular, the latch includes a slot and the eccentric weight, which is rotatably mounted on the shaft, includes a pin that extends axially through the slot. Rotation of the latch in a first direction causes the pin to move to a first end of the slot which, in turn, moves the weight into a low radial position with respect to the axis of rotation, thereby generating a low amplitude of vibration. Furthermore, the slot is C-shaped or L-shaped and a side of the slot engages the pin and thereby restrains the weight from moving into a higher radial position. Rotation of the latch in the reverse direction causes the pin to move to the other end of the slot and causes the eccentric weight to move into a high radial position, thereby generating a high amplitude of vibration.
An object of the present invention is to provide a vibration generator for a compaction machine which exhibits both high and low amplitude of vibration states without utilizing the vibration generator of the '534 Patent.
SUMMARY OF THE PRESENT INVENTION
The vibration generator for a compaction machine of the present invention includes a weight member, a shaft rotatable about an axis of rotation extending longitudinally through the weight member and having a mounting area on which the weight member is mounted, and a positioning arm disposed in engagement with the weight member and rotatable about the axis of rotation relative to both the shaft and the weight member. Rotation of the positioning arm relative to both the shaft and the weight member moves the weight member relative to the shaft in a radial direction orthogonal to the axis of rotation thereby altering the moment of inertia of the weight member about the axis of rotation and resulting in a different amplitude of vibration during rotation of the weight member.
In a feature of the present invention, the mounting area engages the weight member and prevents movement of the weight member relative to the shaft in a circumferential direction about the axis of rotation but permits movement of the weight member relative to the shaft in a radial direction orthogonal to the axis of rotation and coplanar with the circumferential direction. In a preferred embodiment of the present invention, the weight member includes an elongate mounting slot having a pair of opposed parallel planar sides between which the mounting area of the shaft extends, and the mounting area includes parallel planar surfaces disposed in sliding abutment with the planar sides.
In a further feature of the present invention, the weight member defines an elongate positioning slot and the positioning arm includes an axially extending portion disposed through the positioning slot for slidable movement within the positioning slot during rotation of the positioning member relative to the shaft. Furthermore, the axially extending portion in fact defines a cam surface disposed in engagement with the weight member within the positioning slot. In a preferred embodiment of the present invention, the weight member includes a weighted portion and an arm portion extending from the weighted portion, with the weighted portion defining the positioning slot and the arm portion defining the elongate mounting slot. In an alternative preferred embodiment including this feature, the weight member includes a weighted portion, an offsetting portion disposed opposite the weighted portion relative to the axis of rotation, and an arm portion extending between and connecting the weighted portion and the offsetting portion, with the offsetting portion defining the positioning slot and the arm portion defining the elongate mounting slot.
In a further feature of the present invention, the positioning slot extends along its length from an end thereof away from the axis of rotation and then extends in closer proximity to the axis of rotation. In one preferred embodiment including this feature, the positioning slot is generally checkmark shaped. In an alternative preferred embodiment, the positioning slot extends parallel to a plane orthogonal to the axis of rotation and perpendicularly intersects a radial line orthogonal to the axis of rotation.
Preferably, in each embodiment of the present invention the center of mass of the weight member is located in a pie-wedged weighted portion thereof.
The present invention also includes a compaction machine including the vibration generator of the present invention.
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Compaction America, Inc.
Kennedy Covington Lobdell & Hickman L.L.P.
Lillis Eileen D.
Pechhold Alexandra K.
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