Solid material comminution or disintegration – Processes – Wood and similar natural-fibrous vegetable material
Reexamination Certificate
1999-08-26
2001-01-30
Rosenbaum, Mark (Department: 3725)
Solid material comminution or disintegration
Processes
Wood and similar natural-fibrous vegetable material
C241S056000, C241S060000, C241S280000
Reexamination Certificate
active
06179232
ABSTRACT:
This invention relates generally to drum-type wood chippers and more particularly to the handling of the wood chips during discharge.
BACKGROUND OF THE INVENTION
Drum-type wood chippers of the kind typically used to chip tree limbs and other wood debris include a housing having an internal chamber in which a chipper drum is supported for driven rotation. The drum carries a plurality of cutting knives spaced about its perimeter which, when wood debris is fed into the chamber, reduce the limbs and such to chips. The chips are discharged through an outlet in the chamber and transported by their momentum along a discharge chute for collection, typically in a chamber or bin, such as that provided on a towing vehicle used to transport the chipper.
As the type of wood and size of the chips can vary, it is not uncommon for some of the chips to be too light such that they have insufficient momentum to travel the length of the discharge chute and collect in the chamber. One proposed solution to the problem has been to add fan blades to the side of the drum in order to generate a flow of air in the chipping chamber to help carry the chips along. The flow of air, however, is difficult to control and in some cases an undesirable backflow develops wherein dust and light debris is discharged through the material inlet.
Another proposal has been to equip such chippers with a fan external to the housing that is driven off the drum shaft and is coupled by a hose to the discharge chute for creating an air flow in the chute downstream of the outlet which acts to draw and carry the chips along and into the collection bin. While such external fan devices are effective at entraining the chips, there is not always room enough on the chipper apparatus to accommodate the mounting of the external fan assembly. Further, the necessity for an additional air hose from the fan to the discharge chamber detracts from the appearance of the chipper apparatus, is prone to damage, and adds to the maintenance and cost of the apparatus.
SUMMARY OF THE INVENTION
Apparatus for reducing wood debris to chips comprises a support frame having a housing mounted thereon with an internal chipping chamber having a circumferentially extending chamber wall. A chipping drum is supported for driven rotation within the chamber and communicates with a material inlet provided in the chamber wall for introducing wood debris into the chipper chamber for reduction to chips by the drum. A material outlet is provided in the wall for discharging the wood chips from the chamber. A discharge chute is coupled at a receiving end thereof to the housing in communication with the material outlet for receiving and guiding the chips outwardly of the housing to an opposite discharge end of the chute.
According to a characterizing feature of the invention, the apparatus includes a chip entrainment system comprising an internal fan chamber provided in the housing adjacent the chipping chamber that is isolated from the chipping chamber by a fixed partition wall of the housing. A fan is supported for driven rotation within the fan chamber and is operative to draw air into the air chamber through an air inlet of the fan chamber and to discharge a high velocity flow of air through an outlet of the fan chamber in communication with the receiving end of the discharge chute. A baffle is provided in the chute between the chipping and fan outlets of the housing. Air entering the chute from the fan chamber joins the flow of chips issuing from the drum chamber at a location downstream of the material outlet of the chipping chamber so as to entrain the chips and carry them forward toward the discharge end of the chute. The baffle prevents the stream of air from backflowing into the chipping chamber through the material outlet thereof.
The invention offers several advantages over the known prior art chip handling systems, including integrated the air flow system into the housing, eliminating space problems associated with externally mounted fans and the necessity for an external air hose to communicate with the chute. The fixed partition wall and baffle ensure that the air flow generated by the fan entrains the chips as desired downstream of the material outlet, while preventing the air flow from entering the chipping chamber and causing debris to be ejected through the material inlet.
REFERENCES:
patent: 3123311 (1964-03-01), Fontaine
patent: 3276700 (1966-10-01), Eklund
patent: 3332461 (1967-07-01), Ledergerber
patent: 3410495 (1968-11-01), Eklund
patent: 3635410 (1972-01-01), Smith
patent: 3682400 (1972-08-01), Smith
patent: 5060873 (1991-10-01), Strong
patent: 5240188 (1993-08-01), Whitmire
patent: 5240189 (1993-08-01), Majkrzak et al.
Morbark, Inc.
Reising Ethington, Barnes, Kisselle, Learman & McCulloch, P.C.
Rosenbaum Mark
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