Conveyors: power-driven – Conveyor section – Reciprocating conveying surface
Reexamination Certificate
1999-05-14
2001-05-15
Valenza, Joseph E. (Department: 3651)
Conveyors: power-driven
Conveyor section
Reciprocating conveying surface
C198S768000
Reexamination Certificate
active
06230875
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a vibratory conveyor capable of fluidizing particulate material and more specifically to a conveyor that allows variations in the degree of fluidization of a particulate material on a vibratory conveyor together with independent variations in the speed and direction of the material on the conveyor.
Shaker or vibratory conveyors are commonly used for transporting particulate material and may be used for drying particulate material. When used for drying, the degree of fluidization of the material is important to allow drying gas to pass through there or circulate around. Such conveyors invariably have troughs or pans, which may or may not be perforated dependent upon their use. In existing perforated trough conveyors used for drying, the degree of fluidization is dependent at least partly on the gas flow and the retention time of the particulate material being conveyed is dependent upon the speed the material moves in the trough together with the length of the trough.
The invention is the owner or co-owner of the following patents related to the present invention:
U.S. Pat. No. 4,548,623 and Canadian Patent No. 1240918 entitled Perforated Trough Conditioning Device
U.S. Pat. No. 5,816,386 entitled Fluidizer Conveyor
Applicant is also the owner of the U.S. Pat. No. 6,035,543, issued, Mar. 14, 2000, and now U.S. Pat. No. 6,035,543.
Fluidizer conveyors have troughs that are vibrated by mechanical, electrical, pneumatic or hydraulic devices. These include hinged rocker arms, eccentrically loaded wheels, pulsating magnets or pneumatic or hydraulic cylinders.
A review of other available designs for fluidizing with vibrations reveals a fixed relationship between the vertical component for fluidization and the horizontal component for material velocity in the conveyor trough. Typical equipment includes eccentrically weighted motors for conveyor troughs, supported by inclined struts or springs which are caused to rapidly reciprocate horizontally. The vertical and horizontal components of the vibration forces are a function of the sine and cosine of the angle of the supporting strut or spring, or the angle of the axis of the eccentric motor.
Eccentrically weighted motors are used on large helical feeders where control of material velocity is the only requirement. Such motors cannot be too large otherwise the vibration forces produced may become destructive. These vibration forces act in a plane of rotation of 360° whereas the useful vertical forces needed are substantially in a single vertical plane. Thus, there are unproductive vibration forces that if excessive cause damage to the structure. Some designs overcome these problems by providing pairs of eccentric weights phased to offset the horizontal forces.
SUMMARY OF THE INVENTION
To address the above described shortcomings of the prior art, the vibrator conveyor of the present invention has been developed which separates the vibratory forces of fluidization and the vibratory forces that act to convey the particulate material in a conveyor trough or tray. The forces may act separately or in combination. The apparatus of the present invention applies the fluidizing forces in a generally vertical direction and the conveying forces in a generally horizontal direction.
Accordingly, the present invention provides a fluidizer conveyor mountable to a base comprising:
a trough to hold, fluidize and convey particulate material;
at least one reciprocating hydraulic vector cylinder connected between the trough and the base to impart a vibratory motion to the trough to convey material along the trough;
at least one reciprocating hydraulic thrust cylinder connected between the trough and the base to impart a vibratory motion to the trough to fluidize material in the trough;
first control means for the at least one thrust and vector hydraulic cylinders to independently control the amplitude of vibration of each cylinder; and
second control means for the at least one thrust and vector hydraulic cylinders to synchronously control the frequency of vibration of the cylinders;
whereby the first and second control means control movement of the at least one thrust and vector hydraulic cylinders such that the cylinders co-operate to impart a desired vibration motion to the trough at a resultant vector angle.
The frequency of vibration of the vector and thrust cylinders can be synchronized to be in phase or 180 degrees out of phase over frequencies generally in the range 700 to 1500 cycles per minute (cpm). The amplitudes of vibration are independently controlled generally in the range of 0.010 to 0.060 inches.
The present invention uses synchronized frequencies for the horizontal or “Vector” cylinders and the vertical or “Thrust” cylinders. The amplitude applied to the vector cylinders is separately controlled from the amplitude applied to the thrust cylinders. The resultant vector angle of vibration on the trough determines the velocity of material travel in the trough. The vector angle in the plane of vibration is a function of the amplitudes applied to the vector and thrust cylinders. Equal amplitudes will produce a 45-degree vector angle for any frequency applied by the cylinders. If the thrust cylinder amplitude is greater than the vector cylinder amplitude the resultant vector angle will be greater than 45 degrees. Conversely, if the thrust cylinder amplitude is less than the vector cylinder amplitude the resultant vector angle will be less than 45 degrees.
The velocity of material for any vector angle is a function of the vibration frequency and the set amplitudes applied to both cylinders. Velocity will increase or decrease with an increase or decrease in frequency for the set amplitudes. The degree of fluidization is a function of the amplitude of the thrust cylinders. An increase in amplitude will increase fluidization and vice versa. For any set synchronized frequency the velocity of material will increase or decrease as the amplitude of the vector cylinder increases or decreases.
When the vector cylinder frequency lags the thrust cylinder frequency by 180 degrees the direction of material flow will be reversed from the flow direction in the trough. By utilizing variable thrust amplitudes through a range of frequencies one can select the degree of fluidization for any velocity and direction.
When this invention is used for drying particulate material, the conveyor trough may be designed to allow the drying medium, or gas, to pass up through openings in the tray and through the bed of particulate. Fluidization of the particulate with vibrations will allow the gas to flow around each particulate to increase the rate of mass transfer and reduce retention. Fluidization is also discussed in more detail in applicant's U.S. Pat. No. 5,816,386 entitled Fluidizer Conveyor, the contents of which are incorporated herein by reference.
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Kolisch Hartwell Dickinson & McCormack & Heuser
Valenza Joseph E.
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