Vibration unit

Details Vibration unit Vibration unit

2002-05-17

2004-01-06

Will, Thomas B. (Department: 3671)

Harvesters

Fruit gatherer

Tree shaker

Reexamination Certificate

active

06672044

ABSTRACT:

This application is a U.S. National Phase Application Under 35 USC 371 of International Application PCT/IL00/00716 (published in English) filed Nov. 5, 2000.
TECHNICAL FIELD
The present invention relates to tree-shaking harvesting equipment, and in particular to the vibration generation unit which actuates such equipment.
BACKGROUND ART
Traditionally, picking fruit and nuts from trees was always done manually and was inherently labor intensive. With the rise of wages and the increase of competition in the food supply market, efforts were made to mechanize the harvesting of trees and to provide for methods that are more efficient. Because of this quest, tree-shaking machines were developed. Those tree shakers are equipped with a pair of two opposing clamps, which firmly engage a tree on two diametrical sides of the trunk. The tree shaker also comprises a vibration generation unit that is connected to the clamps of the tree-shaking machine. Once the clamps are engaged, the tree is shaken to remove the fruit, with the intent that the inertial forces that will develop on the fruit will exceed the bonding force between the fruit and the stem.
A vibration generation unit is typically driven by a dual oscillation mechanism, which operate substantially independently of one another. An example is provided in U.S. Pat. No. 3,338,040 which shakes the tree in a number of different random directions. Such action is undesirable, because some of these directions may cause damage to the tree. For example, those directions in which the clamps vibrate tangentially to the trunk cause transverse shear which can strip tree bark and abrade the stem. Furthermore, two randomly vibration generation units do sometimes oppose one another and cause energy dissipation; or excessively reinforce one another and thereby exert exaggerated compressive forces on the tree.
Efforts to coordinate the action of the two vibration generating units, such as modification of the moment of inertia of the spinning rotators resulted in U.S. Pat. Nos. 3,548,578 and 4,903,471. But even those improved devices wrench the trees across a range of directions at once, risking damage to the root system. Experiments were also conducted with the variation of the frequency of shaking, to reach the natural resonance frequency of the tree. It was thought that if it would be possible to reach the maximum amplitude of displacement, then the most efficient tree harvesting conditions would be s obtained. A limb shaker having a variable throttle arrangement that can be adjusted until the greatest displacement is observed is taught in U.S. Pat. No. 3,650,099. However, with a manual throttle setting device, the shaker was poorly suited for commercial harvesting.
In a paper of the American Society of Agricultural Engineers, by J. D. Whitney, G. H. Smerage and W. A. Block, No. 0001-2351/90/3304-1066, published in April 1990, there is mention of a shaking system with a three-shaft linear vibrator. As shown in
FIG. 1
, the elements of the system comprise a vibration unit A, a tree clamp C engaging a trunk B and part of the shaker machine D. The vibration unit A consists of three identical vertical sprocket wheels mounted side by side on a horizontal frame beam F inside a housing H. One sprocket wheel MS, the middle one for example, is driven by a motor M, not shown in
FIG. 1
for the sake of clarity, and the other two sprocket wheels, on the sides of the driven sprocket wheel MS, are driven sprockets S. A chain CH couples the three sprocket wheels, with the slack side SS of the chain CH, running substantially in parallel and below the frame beam F. The slack side SS is tensioned by an idler ID. The two driven sprocket wheels S are engaged by the chain CH to rotate in the same direction while the middle driving sprocket MS counter-rotates. This is achieved by running the chain over both side sprocket wheels S but under the driven sprocket wheel MS.
To generate vibrations, the sprocket wheels carry eccentric weights. A single weight G is mounted eccentrically on each one of the sprocket wheels S while a double weight 2G is mounted with the same eccentricity on the driven sprocket wheel MS. With reference to
FIG. 1
, the single weights G and the double weight 2G are all aligned to the east, according to the directions of the compass card. A force vector equal to the sum of forces applied by the two single weights G and the one double weight 2G is thus applied eastwards.
Assuming that the driven sprocket wheel MS rotates anti-clockwise, then both sprocket wheels S will rotate clockwise.
FIG. 2
now represents the s vibration unit A after a quarter of a turn of the sprocket wheels, according to the assumed direction of rotation. The single weights G on the sprocket wheels S now point northwards while the double weight 2G points southwards. The force vector of the sum of forces applied all the weights, namely, two single forces G pointing to the north and one double weight 2G directed to the south, now equals zero, and thereby, the upward and the downward forces cancel out.
Another quarter of turn of the sprocket wheels is depicted in FIG.
3
. This time all the weights are aligned westwards. The resultant force vector is thus the same as at the start, as shown in
FIG. 1
, but in the opposite direction. One more quarter of a turn, not illustrated in a drawing, would result in a rotation of 180 degrees of all the sprocket wheels relative to
FIG. 2
, whereby the force vector would again sum up to zero. It has thus been shown that the vibration unit A is a linear shaker: theoretically, forces appear only horizontally, in the east to west direction, while no forces are generated vertically, north-south.
In practice however, the results are quite different. First, the vibration unit A is limited to rather slow rotational velocities, due to the chain drive, which makes it unfit for the harvesting of smaller fruit. Second, the vibration unit A develops severe wear and tear, resulting in costly maintenance expenses. Third, the vibration unit A engages the tree trunks with its longitudinal axis in the direction of shaking, thus rendering it very awkward to operate.
Although tree shakers are readily available, their vibration generating units still suffer from various drawbacks such as slippage, loss of rotational synchronization which causes deviation from a single shaking direction, as well as damage to tree trunks and overall low harvesting efficiency.
For the above-mentioned reasons, there is obviously a need for better vibration generating units that keep their synchronization, are cheap to maintain and operate, and are easy to use. Moreover, there is definitely a need for equipment which features high efficiency harvesting and is inexpensive to manufacture.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a vibration generation mechanism for the high efficiency harvesting of trees.
It is another object of the present invention to provide a vibration generation mechanism, which is simple to use and operate.
It is a further object of the present invention to provide a vibration generation mechanism that will not harm the trees during shaking.
It is yet another object of the present invention to provide a unitary improved but simple vibration generation mechanism featuring low costs of production, of operation and of maintenance.
Still another object of the present invention is to provide a vibration generation mechanism, which is reliable and long lasting.
It is an object of the present invention to provide a linear vibration generation mechanism for a tree trunk shaker, the shaker comprising a pair of clamps for locking on the trunk on opposite sides thereof and the linear vibration generation mechanism comprising:
at least one motor for providing rotational motion at a predetermined angular velocity,
a transmission coupled to the at least one motor, the transmission for providing a counter-rotating motion,
a pair of identical eccentric rotators coupled to the provided counter-rotating motion, the pair of eccentric rotators

Affiliated with

Also associated with

Rating

Vibration unit does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Vibration unit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vibration unit will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3197650