US 3765173 A
An apparatus for agglomerating particulate material as in a briquetting or compacting construction. The improvement of the invention relates to drive means for the agglomerating rolls. The drive means include individual hydraulic motors for the rolls with separate or common pumps being employed in conjunction with the hydraulic motors. Detecting means may be connected to at least one of the roll shafts for thereby determining the relative angular positions of the rolls mounted on the shaft. Control means are operated by the detecting means so that momentary variations in the speeds of rotation of the rolls can be made to synchronize the rolls. The control system preferably comprises an automatic quick response arrangement so that the rolls are maintained at proper synchronization throughout the agglomerating operation.
Description (OCR text may contain errors)
United States Patent 11 1 Harris HYDRAULIC ROLL DRIVE MEANS FOR BRIQUETTERS AND COMPACTORS  Inventor: Leroy S. Harris, Rolling Meadows,
 [1.8. CI. 60/97 E, 60/420, 91/171,
, v 425/168  Int. Cl. FlSb 11/22  Field of Search 60/97 E, 97 S, 420;
Primary Examiner-Edgar W. Geoghegan Attorney-McDougall, Hersh & Scott 7 ABSTRACT vidual hydraulic motors for the rolls with separate or common pumps being employed in conjunction with the hydraulic motors. Detecting means may be connected to at least one of the roll shafts for thereby determining the relative angular positions of the rolls mounted on the shaft. Control means are operated by  References Cited the detecting means so that momentary variations in UNITED STATES PATENTS the speeds of rotation of the rolls can be made to synchronize the rolls. The control system preferably comg 2 g 3 prises an automatic quick response arrangement so OWCI' 3,550.205 12/1970 Guseman et al. 425/168 x that the mus are mamtamefi at Synchmmzam throughout the agglomeratmg operatlon. FOREIGN PATENTS OR APPLICATIONS 845,054 8/1960 Great Britain 60/97 E Clam, 5 D'awmg figures f0 55 14 ,i 30 i ROLL W 1 62E ROLL XE a4 4 12 50/ VARIABLE DISPLACEMENT 46 HYDRAULIC PUMPS 3a 1 EL ECT MOTOR ELECTRICAL commons/e 6 NULL SIGNAL BALANCE TYPE. 1
LELECTRIC SIGNAL com arator 52 i0 .F IGZZ VARIABLE 'DISPLACEME HYDRALI LIC PUM PS EL ECT MOTOR ELECTRICAL coumouelz NULL SIGNAL BALANCE TYPE COMPARATOR 52 v E LECTRI C SIGNA L v HYDRA'ULIC EL -n2 K2 R0 L M T R MOTOR HYDRAULIC ELECTRIC R0 L L M01012 MOTOR PAIENIEIIIII I W 4 3. 765. 1 73 I SHEET F 2 I FIGA 5 26 I HY RA ROLL 2 72 K74 ELECITQIC MOTOR ROLL HYDRAULIC I moTqIz (12 76 I FIG. 4 78 DIFFERENTIAL DIFFERENTIAL TRAI IsFoRMEIa TRANSFORMER numb /NULL BALANCE (D INDICATORAND CONTROLLER L88 F! G, 5 I
ll-REVOLUTION A 7 I l 0 90 I 270 360 I SIGNAL FROM SIGNAL FROM "A" oII=I=. TRANSFORMER "B' DlFF. TRANSFORMER 1 HYDRAULIC ROLL DRIVE MEANS FOR BRIQUETTERS AND COMPACTORS This invention is directed to drive means for agglomerating constructions. The invention is particularly concerned with constructions such as briquetters and compactors which employ a pair of rolls, and which have means for feeding particulate material between the rolls. The rolls are mounted so that high pressure is applied to the particulate material passing between the rolls.
Briquetters and compactors have commonly employed speed reducers in conjunction with roll drive systems. Speed reducers perform the desired function of controlling various drive characteristics; however, in briquetting and compacting operations, the speed reducers are subjected to excessive gear loading whereby gear wear becomes a significant problem. Excessive loading is experienced by speed reducer internals when the torque on one roll varies from O to 100 percent in a substantially instantaneous fashion. The sharp loading causes torsional flexing in the internals with excessive wear and consequent expense to the customer A being the result. These problems occur in rather regular fashion on any large units used for briquetting and compacting purposes.
In the case of briquetting machines, the rolls may define opposed pockets whereby the particulate material will be formed into briquets. Flat sheets or other compacted forms can also be produced with constructions of this type. It has been found that the quality of a briquet or other compacted article depends to some extent on the nature of the forces which are applied during an agglomerating operation. In an ideal situation, the forces applied are substantially all compressive forces; however, various factors can lead to differential stress including shear and tensile forces. Where an ideal force distribution does not occur, the agglomerated product may contain cracks or other defects.
In briquetting machines, it has been recognized that the best force distribution during agglomerating is achieved when the agglomerating rolls operate at substantially the same speed with the pockets thereof being in an aligned relationship during briquet formation. Speed reducers have been employed so that the operation of one roll can be synchronized with the operation of another roll. As indicated, however, the speed reducers create other problems since their operation requires a rather substantial application of force to gears which leads to excessive loading and to gear wear.
It is a general object of this invention to provide an improved hydraulic drive system for briquetting and compacting equipment.
It is a more specific object of this invention to provide improved drive arrangements for the rolls of briquetting and compacting machines whereby roll synchronization can be maintained without requiring excessive loading and without incurring excessive wear of component parts.
These and other objects of this invention will appear hereinafter, and for purposes of illustration, but not of limitation, specific embodiments of the invention are shown in the accompanying drawings in which:
FIG. 1 is a diagrammatic illustration ofa briquetting construction characterized by the features of this invention;
FIG. 2 is a schematic illustration of a slightly modified version of the invention shown in FIG. 1;
FIG. 3 is a schematic illustration of a further modified version ofthe invention;
FIG. 4 is a detailed schematic illustration of a combined roll position detecting and control system which may be utilized in the practice of the invention; and,
FIG. 5 is a graphical illustration of the operating characteristics of the detecting means shown in FIG. 4.
The apparatus of the invention relates to a briquetting and compacting construction or any other similar apparatus employed for agglomerating particulate material. Particularly included are constructions which include a pair of agglomerating rolls along with means for feeding particulate material through the rolls whereby briquets, compacted sheets, or similar products can be formed.
The invention is particularly concerned with improved drive means for the agglomerating rolls. Specifically, the drive means consist of a pair of hydraulic motors with one motor being connected to each roll. Pump means are employed for operating the hydraulic motors, and a separate electric motor or the like is utilized for operating the pump means.
The structures of the invention may include a detecting and control system utilized for achieving momentary variations in the speed of rotation of the agglomerating rolls so that roll synchronization can be maintained throughout the agglomerating operation. The detecting means preferably comprise a pair of signal generators connected directly to the rotating shafts carrying the agglomerating rolls. The signals generated are fed to a comparator, and if the agglomerating rolls are in proper synchronization, then there will be no net signal observed by the comparator. On the other hand, if there is a difference in the angular positions of the rolls, then an output from the comparator will serve to momentarily vary the roll speeds to bring the rolls back to proper synchronization. By providing a quick response system, the agglomerating rolls can be maintained in substantially constant synchronization thereby providing a uniform and satisfactory production.
FIG. 1 illustrates a system incorporating various aspects of the instant invention. In this system, a pair of briquetting rolls l0 and 12 are mounted on supporting shafts 14 and 16 which are in turn supported by bearings l8 and 20. The shafts are connected through couplings 22 and 24 to hydraulic drive motors 26 and 28.
The hydraulic drive motor 26 is connected through lines 30 and 32 to a variable displacement hydraulic pump 34. This pump is connected through couplings 36 to an electrical drive motor 38.
The drive motor 38 includes a first shaft 40 connected to the coupling 36 and a second oppositely extending shaft 42 connected to coupling 44. The coupling 44 is connected to hydraulic pump 46 which is in turn connected through lines 48 and 50 to the other hydraulic motor 28.
A speed adjusting control 52 is attached to the variable displacement pump 34. This speed adjuster may include an appropriate manual control so that the displacement of the pump 34 can be located at a desired position. With this arrangement, the hydraulic drive motor 26 will perform in a fixed fashion unless an adjustment is made by means of the construction 52.
The roll drive system described may be complemented by an electric controller 54 connected to the pump 46. The controller may be a null signal balance type as illustrated or any comparable type. The controller is operated by the output of an electric signal comparator 56. The comparator 56 is connected to a pair of roll position detecting devices 58 and 60. The detector 58 is associated with the shaft 62 which extends outwardly from, and is formed integrally with, the roll supporting shaft 14. Similarly, the detector 60 is associated with the extension 64 of the shaft 16.
The detectors 58 and 60 may be of various types including position transducers, precision electrical tachometers, Selsyn motors and rotary differential transformers. In any event, the output from the detectors is fed to the comparator 56 whereby the output of the comparator will depend on any differences in the roll positions. If the roll positions are synchronized, when the comparator output will be zero so that the controller 54 will not change the displacement of pump 46. Where the rolls are out of synchronization, the comparator 56 will develop a signal proportional to the differences in position thereby causing the controller to make a proportional change in the displacement of pump 46. The adjustment will continue until the rolls return to proper synchronization.
FIG. 2 illustrates a modification of the roll drive means of the invention. In this arrangement, the pumps 34 and 36 are each provided with a separate electric motor 66 and 68. Where a roll synchronization means is desired, the pumps could be controlled by the system illustrated in FIG, 1 with the electric motors 66 and 68 operating at equal fixed speeds. On the other hand, detectors such as the detectors 58 and 60 may be connected to a controller 70 for one of the electric motors. By providing a variable speed electric motor, departures from roll synchronization can be employed for developing a signal which will lead to a variation in the output of pump 34 to eventually accomplish and then maintain roll synchronization.
In the embodiment shown in FIG. 3, a single pump 72 and a single electric motor 74 are provided. The output from the pump 72 is divided between the hydraulic motors 26 and 28. With this arrangement detectors such as shown at 58 and 60 may be associated with a by-pass valve 76 connected between the pump and one of the hydraulic motors. Any departures from synchronization will proportionally control the operation of this bypass valve thereby affecting the operation of the hydraulic motor 28. Again, the detecting and control means will operate to equalize and maintain the roll synchronization. The same results can be achieved if the by-pass valve or a flow retarding valve is inserted directly in the line between pump 72 and hydraulic motor 28.
FIGS. 4 and illustrate one suitable detecting arrangement for achieving roll synchronization. In this arrangement, the shaft extensions 62 and 64 are each provided with four equally spaced cams 78. The detectors associated with these shaft extensions comprise differential transformers 80 and 82. These transformers include reciprocally mounted armatures 84 and 86 and the armatures are spring loaded so that the ends thereof will ride on the cam surfaces. As the shafts rotate, the positions of the armatures relative to the transformer windings will vary thereby producing a varying electrical output signal.
The characteristics of the output signals are illustrated in FIG. 5. As indicated, equal and opposite signals are produced by the respective transformers, and when the cams have the same alignment on each shaft, there will be no variation in the angular positions of the shafts and the combined output will be zero.
The transformers are connected so that the individual outputs are of opposite polarity. The respective signals are then bucked against one another in the manner shown or in a simple Wheatstone bridge circuit. A signal will be generated whenever the respective outputs from the transformers are not equal and opposite during every degree of rotation of the rolls. Any differential signal produced can then be fed to a null balance type of electrical controller which will produce a signal to momentarily adjust the relative roll speeds until synchronization is achieved.
In the example illustrated, the signals vary between zero and I00 percent in 45 of angular rotation, and the magnitude of any signal to the controller will depend on the respective positions of the cams on the roll shafts. A very accurate synchronization can be achieved. Thus, a typical system will have an accuracy of about two percent or less so that the rolls can be kept in angular position synchronization within O.9 of angular rotation. It will be appreciated that the number of cams can be varied and that other means can be employed for detecting the relative positions of the roll shafts and then using this information for providing momentary variations in roll speed.
As indicated, the output controller may be applied to one of the pumps, to an electric motor driving a pump, to a flow control valve, to a by-pass valve associated with one of the hydraulic drive motors, or to any other appropriate mechanism which will serve to synchronize the roll operations.
In briquetting, double output shaft speed reducers are commonly used to minimize expense; however, this restricts the use of different roll sizes. The hydraulic systems described are much more compatible with changes in roll sizes.
It has also been found that systems incorporating the teachings of this invention are highly efficient when compared with prior art systems ofthe type using speed reducers. Specially designed, double output, speed reducers are often required and these are relatively expensive. The concepts of this invention do not lead to excessive gear loading or gear wear or to other conditions which lead to deterioration of a drive system.
Where roll position detectors are utilized, the individual elements employed in the system are all of a relatively simple nature and elements such as the comparator, controller and adjuster structures are standard items which, therefore, can be readily obtained.
It will be understood that various changes and modifications may be made in the above described construction which provide the characteristics of this invention without departing from the spirit thereof particularly as defined in the following claims.
That which is claimed is:
1. In an apparatus for agglomerating particulate material including a pair of agglomerating rolls defining mating material shaping portions and means for feeding material between said rolls, the improvement in drive means for said rolls comprising a pair of hydraulic motors, each of said motors being connected to a particular one of said rolls, hydraulic pump means connected to said hydraulic motors, and additional motor means for operating said pump means, means for setting the speed of one of said hydraulic motors, detecting means connected to at least one of said rolls for determining the angular position thereof, and control means connected to said detecting means, said control means being connected to the other of said hydraulic motors for synchronizing the angular position of said other hydraulic motor with the angular position of said one hydraulic motor having the set speed.
2. An apparatus in accordance with claim 1 wherein said pump means consists of a pump attached to each hydraulic motor, a least one of said pumps being of the variable displacement type, said one pump being connected to said other hydraulic motor and said control means operating to vary the displacement of said one pump in response to the operation of said detecting means.
3. An apparatus in accordance with claim 1 including one pump connected to both of said motors, and including a by-pass valve connected between said pump and at least one of the hydraulic motors, said control means operating to control the flow of hydraulic fluid through said by-pass valve in response to the operation of said detecting means.
4. An apparatus in accordance with claim 2 wherein the motor means driving said pumps comprises a double shaft electric motor, said electric motor serving to drive both of said pumps.
5. An apparatus in accordance with claim 2 wherein said motor means comprises a separate electric motor for each of said pumps.
6. An apparatus in accordance with claim 1 wherein said pump means comprise a separate pump for each hydraulic motor, said motor means comprising a separate electric motor connected to the respective pumps, and wherein said control means are connected to at least one of said electric motors.
7. An apparatus in accordance with claim I wherein said indicating means comprise electrical signal generators connected to shafts carrying said rolls whereby signalsare generated in accordance with the angular positions of said rolls, said control means comprising a signal comparator adapted to produce an output corresponding to the difference in angular positions of said rolls.
8. An apparatus in accordance with claim 7 wherein said electrical signal generators comprise a pair of transformers each carrying a movable armature, a cam mounted on each of the shafts carrying said rolls, the respective cams being engageable with the movable armatures of said generators, said cams being of an identical configuration so that movement of the armatures relative to the respective transformer windings will be synchronized when said rolls are synchronized.
9. An apparatus in accordance with claim 1 including one pump connected to both of said motors.
10. In an apparatus including a pair of rolls, and drive means for said rolls, the improvement comprising detecting means connected to at least one of said rolls for determining the angular position thereof, and control means connected to said detecting means for synchronizing the angular positions of said rolls, said indicating means comprising electrical signal generators connected to shafts carrying said rolls whereby signals are generated in accordance with the angular positions of said rolls, said control means comprising a signal comparator adapted to produce an output corresponding to the difference in angular positions of said rolls, said electrical signal generators comprising a pair of transformers each carrying a movable armature, a cam mounted on each of the shafts carrying said rolls, the respective cams being engageable with the movable armatures of said generators, said cams being of an identical configuration so that movement of the armatures relative to the respective transformer windings will be synchronized when said rolls are synchronized.