MATERIAL AND METHODS FOR BALANCING ROTORS

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62/289,684, filed February 1, 2016, which is incorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

[0002] The field of the disclosure relates to self -balancing rotors and, in particular, self -balancing cylindrical rotors for comminuting materials such as biomass and terrain. The field of the disclosure also relates to methods for balancing such rotors.

BACKGROUND

[0003] Cylindrical rotors are used for various mulching, cutting and leveling operations. Such rotors include a number of cutting elements spaced about the rotor to cut, rip, shred or otherwise reduce the particle size of the material. Mulching apparatus that include such rotors include tub grinders, horizontal grinders, bale processors and forestry tractors or mowers. Terrain levelers used for surface excavations such as for mining operations also include a cylindrical rotor. [0004] Cylindrical rotors may become imbalanced in the field for a variety of reasons including wear of the cutting elements, substitution of the cutting elements for different elements (e.g., different cutting element

arrangements such as elements with different a bite) and build-up of material. A need exists for cylindrical rotors for comminuting material that may be self-balanced and for rotors that maintain a balanced condition throughout

acceleration and deceleration of the rotor during use.

[0005] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to

facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

SUMMARY

[0006] One aspect of the present disclosure is directed to a self -balancing rotor. The self -balancing rotor comprises a rotor having an axis of rotation and comprises a balancing mechanism. The balancing mechanism comprises a circular channel that extends around the axis of rotation of the rotor and a set of balancing members within the circular channel for balancing the rotor. The self -balancing rotor also includes a locking device that is adjustable from an unlocked state in which the balancing members may move within the circular channel to a locked state in which the balancing members are restricted from moving within the circular channel .

[0007] Various refinements exist of the features noted in relation to the above-mentioned aspects of the present disclosure. Further features may also be

incorporated in the above-mentioned aspects of the present disclosure as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments of the present disclosure may be incorporated into any of the above-described aspects of the present disclosure, alone or in any combination.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a perspective view of a forestry mower;

[0009] Figure 2 is a perspective view of a horizontal grinder;

[0010] Figure 3 is a perspective view of a tub grinder;

[0011] Figure 4 is a partial side view of a surface excavation machine;

[0012] Figure 5 is a partial perspective view of a cylindrical rotor for comminuting material;

[0013] Figure 6 is a partial perspective view of the cylindrical rotor with the shell and a disk and cutting element not shown; [0014] Figure 7 is a partial perspective view of another embodiment of the cylindrical rotor having

cylindrical balancing members with the shell and a disk and cutting element not shown;

[0015] Figure 8 is a partial cross-section side view of the cylindrical rotor of Figure 6;

[0016] Figure 9 is a partial perspective view of the cylindrical rotor with the shell, a disk, and cutting element not shown;

[0017] Figure 10 is a partial cross-section side view of a second end of the cylindrical rotor;

[0018] Figure 11 is a partial cross-section side view of a second end of the cylindrical rotor having a separate actuator;

[0019] Figure 12 is a partial perspective view of another embodiment of a cylindrical rotor;

[0020] Figure 13 is a partial cross-section side view of the rotor of Figure 12;

[0021] Figure 14 is a partial cross-section view of another embodiment of the cylindrical rotor with the shell, a disk and cutting element not shown;

[0022] Figure 15 is a schematic of a self- balancing cylindrical rotor having two balancing mechanisms;

[0023] Figure 16 is a cross-section view of a self -balancing disk rotor; and

[0024] Figure 17 is a cross-section view of a self -balancing disk rotor having a fluid transfer system. [0025] Corresponding reference characters indicate corresponding parts throughout the drawings.

DETAILED DESCRIPTION

[0026] An embodiment of a cylindrical rotor system (or simply "rotor") for comminuting material is generally referred to as "5" in Figure 5. The rotor 5 includes a cylindrical shell 6 and number of cutting elements 7 attached to and spaced about the rotor 5 for comminuting material during rotation of the rotor. The cutting elements 7 are between disks 10 of the cylindrical rotor 5 that are attached to the shell 6. In other embodiments, the rotor 5 does not include disks. The rotor 5 may include other elements (not shown) that are typical for rotors used to comminute material. The rotor 5 has an axis of rotation A about which the rotor rotates in the direction indicated by arrow B. The rotor 5 may be referred to herein as a "rigid" rotor. Such rigid rotors are considered to be "non- deformable" and are characterized by a negligible deformation or deflection in terms of the dynamics of the rotor.

[0027] The cylindrical rotor 5 may generally be part of any apparatus that uses rotational force of the rotor 5 to comminute material. The cylindrical rotor 5 illustrated in Figure 5 is part of a forestry tractor 100 (Fig. 1)

(otherwise referred to as a "forestry mower" or "above ground mulcher") . Other devices having a cylindrical rotor 5 with cutting elements 7 that may be balanced as described herein include, without limitation, horizontal grinders 200 (Fig. 2), tub grinders 300 (Fig. 3) and surface excavation machines 400 (Fig. 4) . [0028] As referenced herein, "comminute" refers to any operation in which the particle size of material is reduced. Suitable cutting elements 7 including any elements that are designed to cut, crush, chip, grind, tear, shred, or otherwise reduce the size of material such as biomass, refuse, or terrain. Cutting elements 7 that may be used in various comminuting apparatus include cutting teeth, cutting knives, hammers, flails and impactors . The cutting elements may be rigidly attached to the rotor or may swing from the rotor (e.g., bale flails as shown in U.S. Patent Pub. No. WO 2015/038310, which is incorporated herein by reference in its entirety) .

[0029] The cylindrical rotor 5 has a first end 59, a second end 61 (Fig. 10), and a central plane C that is perpendicular to the axis of rotation A of the rotor. The central plane C is equidistant from the first end 59 and the second end 61.

[0030] The cylindrical rotor 5 includes a first balancing mechanism 11 (Fig. 6) and a second balancing mechanism 12 (Fig. 10) . The first balancing mechanism 11 lies in a first plane D (Fig. 15) disposed between the central plane C and the first end 59 (i.e., lies on a first side of the central plane C) . The second balancing mechanism 12 lies in a distinct second plane D between the central plane C and the second end 61 (i.e., lies on a second side of the central plane C) . In the illustrated embodiment, the central plane C, first plane D, and second plane E are parallel to one another and are perpendicular to the axis A. The first plane D and the second plane E are also

equidistantly spaced from the central plane C in the

illustrated embodiment. [0031] The first balancing mechanism 11 includes a first circular channel 13 that extends around the axis of rotation A of the rotor 5. The first balancing mechanism 11 also includes a first set of balancing members 17 that are located within the first circular channel 13. The first balancing mechanism 11 allows the rotor 5 to self-balance by distribution of the balancing members 17 around the channel 13. The balancing members 17 may be shaped as spheres as shown in Figure 6 or may be cylinders as shown in Figure 7. If the balancing members 17 are cylinders, the cylinders are oriented such that the axis of the cylinder is parallel to the axis of rotation A of the rotor 5. While the balancing members 17 are shown as being adjacent to each other in Figures 6 and 7, the balancing members 17 may be spaced about the channel 13 such as during rotation of the rotor 5.

[0032] The shell 6 of the cylindrical rotor 5 includes an inner surface 18 (Fig. 8) and an outer surface 19. As illustrated in Figures 5-11, the first set of balancing members 17 are within the shell 6 such that the inner surface 18 of the shell 6 forms a top wall (i.e., the wall furthest from the central axis A) of the channel 13. Alternatively, the balancing members 17 may be outside of the shell 6 and the outer surface 19 of the shell 6 forms a floor (i.e., the wall nearest the axis A) of the channel 13. In other embodiments, the shell 6 does not form a wall of the channel 13.

[0033] The first balancing mechanism 11 also includes a floor 20 opposite the inner surface 18 of the shell 6 (i.e., opposite the top wall) and an outer sidewall 21 and an inner sidewall 22 opposite the outer sidewall 21 which define the channel. In other embodiments, the floor 20 is eliminated and the balancing members 17 are constrained in the channel 13 by gravity and/or centrifugal force.

[0034] A damping material may be included in the channel 13 to slow the rate at which the balancing members 17 move within the channel 13 during balancing and during acceleration and declaration of the cylindrical rotor 5.

Suitable damping materials include oil and grease.

Alternatively or in addition, the material of construction of the balancing members 17 and the channel 13 may be selected to provide adequate damping.

[0035] The number of balancing members 17 within the shell may be 2 or more, 3 or more, 5 or more, 7 or more, or 11 or more (e.g., from 2 to 20 or from 2 to 15) . The number of balancing members 17 may be chosen based on a variety of factors including the size of the balancing members, the damping medium (if any) , the degree of

imbalance, the radius of the channel 13 and the like.

[0036] The first balancing mechanism 11 and second balancing mechanism 12 allow the rotor 5 to self- balance by distribution of the balancing members around their respective channel. When allowed to freely move about the channel, the balancing members move relative to each other during rotation of the rotor 5 to a resting positon in which the rotor is balanced. The balancing members act to

collectively counter-balance changes in the center of mass of the rotor 5 to allow the center of mass to gravitate to the axis of rotation A at which the rotor 5 is balanced.

[0037] The cylindrical rotor 5 includes a first stem portion 23 that extends from the shell 6. The stem portion 23 rotates within a hub 24 which may be attached to a frame of the comminuting apparatus. The rotor 5 also includes a locking device 25 that is adjustable between an unlocked state (i.e., unlocked position), in which the balancing members 17 may move within the circular channel 13 and a locked state (i.e., locked position), in which the balancing members 17 are restricted from moving within the circular channel 13.

[0038] The first locking device 25 includes a first locking surface 31 that contacts the balancing members 17 when the locking device 25 is in the locked position. As shown in Figure 8, this locking surface 31 is the inner surface of the outer sidewall 21 of the channel 13. The outer sidewall 21 also includes a number of grooves along it circumference that act to restrain movement of the balancing members 17 in the locked position.

[0039] The first locking device 25 includes an actuator 37 attached to the hub 24 for adjusting the locking device 25 between the locked position and the unlocked position. The actuator 37 illustrated in Figures 5-10 is a lever connected to a caliper that controls the speed of a rotating disk 39 and attached locking device shaft 42. The locking device shaft 42 extends through a bushing within the stem 23 of the cylindrical rotor 5. The locking device shaft 42 is received in a recess of a rotor shaft 43. The locking device shaft 42 and rotor shaft 43 are in a threaded

engagement. Operation of the actuator 37 causes the locking device shaft 42 to rotate slower with respect to the rotor shaft 43 which causes the locking device shaft 42 to thread into the recess of the rotor shaft 43. The actuator 37 may be connected to additional cables or linkages to allow the actuator to be operated further away from the rotor 5. [0040] The locking device shaft 42 is attached to a collar 44 which contacts a bracket 45. The bracket 45 is connected to two tie -rods 50 which are in turn connected to the outer sidewall 21 (Fig. 8) of the channel 13 (i.e., the sidewall 21 acts as a locking disk) . In the locked position, the sidewall 21 contacts the balancing members 17 to hold them in place between outer sidewall 21 and inner sidewall 22. Biasing elements 55 (e.g., springs as shown) bias the outer sidewall 21 into the unlocked position. The outer sidewall 21 is capable of moving laterally between the locked and unlocked positions within a gap toward the outer end 59 of the rotor 5.

[0041] During rotation of the cylindrical rotor 5, the shell 6, cutting elements 7, stem 23, rotor shaft 43, locking device shaft 42, disk 39, bracket 45, channel sidewalls 21, 22 and balancing members 17 rotate about the cylindrical axis A of the rotor 5. The lever 37 and the structures used to slow the disk 39 (i.e., caliper, as shown) do not rotate with the rotor 5.

[0042] During balancing, the sidewall 21 is in the unlocked position which allows the balancing members 17 to move freely within the channel 13. After balancing is complete, the lever 37 is actuated to move the sidewall 21 into the locked position. Actuation of the lever 37 of the locking device 25 causes the disk 39 and the locking device shaft 42 to slow (or even stop) its rate of rotation which causes the shaft to rotate relative to the remainder of the rotor 5. The relative rotation between the locking device shaft 42 and the rotor shaft 43 causes the locking device shaft 42 to thread into the rotor shaft 43 and move inward (i.e., away from the nearest end 59 of the rotor 5) . The collar 44 contacts the bracket 45 and causes the bracket 45, tie rods 50 and outer sidewall 21 to also move inward, (i.e., in this position, the width of the channel 13 is reduced to constrain the balancing members 17) .

[0043] As shown in Figure 10, the cylindrical rotor 5 includes a second balancing mechanism 12 and second locking device 62 toward its second end 61. The second balancing mechanism 12 is generally identical to the first balancing mechanism 11. The second balancing mechanism 12 includes a second circular channel 65 and a second set of balancing members 67 for balancing the rotor 5. The channel 65 is formed by a top wall 69, floor 71, inner sidewall 73 and outer sidewall 75. The channel 65 may include damping material therein to slow the rate at which the second set of balancing members 67 move within the second channel 65. The cylindrical rotor 5 also includes a second stem portion 79 that rotates within a second hub 81. The second stem portion 79 may extend out from the hub 81 to allow the stem to be connected to a drive mechanism.

[0044] The second locking device 62 is also adjustable between an unlocked position, in which the second set of balancing members 67 may move within the circular channel 65 and a locked position, in which the second set of balancing members 67 are restricted from moving within the second circular channel 65 by contact with a second locking surface 83. The second locking surface 83 is the inner surface of the outer sidewall 75 of the channel 65. The second locking device 62 also includes a second bracket 93 and second tie rods 95 attached to the outer sidewall 75 of the channel 65. Second biasing elements 96 bias the sidewall 21 into the unlocked position. [0045] Upon actuation of the first actuator 37 (Fig. 8) , the locking device shaft 42 threads into the rotor shaft 43 which causes the two shafts 42, 43 to move toward each other. Movement of the rotor shaft 43 toward the first end 59 of the rotor 5 causes the second bracket 93, second tie rods 95 and second locking surface 83 to move away from the second end 61 to reduce the width of the second channel 65 and to cause the locking surface 83 to contact the second set of balancing members 67.

[0046] In other embodiments and as shown in Figure 11, the second locking device 62 may include a second actuator 87 to adjust the locking device 62 into the locked position. In this embodiment, operation of the first actuator 37 (Fig. 5) does not cause the rotor shaft 43 to move. The second locking device 62 is generally identical to the first locking device 25. The second actuator 87 is connected to a second disk 89 attached to a second locking device shaft 91. The linkages (not shown) attached to the first actuator 37 (Fig. 5) and second actuator 87 (Fig. 11) may be configured to allow both locking devices 25, 62 to be concurrently actuated into the locked and unlocked positons.

[0047] The cylindrical rotor 5 may be balanced by positioning the locking devices 25, 62 in the unlocked position and rotating the cylindrical rotor 5. The locking devices 25, 62 may be moved to the unlocked position by use of a specialty tool (not shown) that causes the locking device shaft 42 to unthread from the rotor shaft 43. The disk 39 or locking device shafts 42, 91 may include an unlocking element (not shown) that allows a standard tool such as a socket or driver bit to be used to unthread the device shaft 42 from the rotor shaft 43. [0048] After positioning the locking devices 25, 62 into the unlocked position, the rotor 5 is rotated and the first and second sets of balancing members 17, 67 move within the circular channels 13, 65 to a "resting position" in which the cylindrical rotor 5 is balanced (i.e., the balancing members of a set move relative to each other in the

respective channel until arriving at a balanced position relative to one another) . After balancing (which may occur after several seconds or even a minute or more) , the locking devices 25, 62 are actuated to the locked position in which the balancing members 17 are restricted from moving within the circular channel 13.

[0049] The balancing mechanisms 11, 12 may be sized and arranged to allow the cylindrical rotor to become balanced within a matter of minutes or even seconds.

Referring now to Figure 15, in some embodiments, a monitoring system (e.g., controller 97 and accelerometers 98 at both ends of the rotor 5) is used to monitor the balance of the rotor 5 and/or to control the locking and unlocking of the balancing mechanisms. The monitoring system may detect change of the vibration amplitude caused by the imbalance of the rotating frequency of the motor. The monitoring system may detect an imbalanced condition of the rotor 5 during use. For example, the monitoring system may detect an imbalanced condition of the rotor and subsequently alert an operator to perform a balancing operation. Alternatively, the monitoring system may automatically initiate a balancing operation after an imbalanced condition is sensed. The monitoring system may also be used to detect when the rotor has become balanced during balancing. [0050] Other embodiments of the monitor system may include a timer. For example, the timer may be used to track the amount of time that the device has been used since a previous balancing operation and to alert an operator that a balancing operation is recommended. Alternatively, the timer may automatically initiate a balancing operation.

[0051] Alternatively or in addition, a timer may be used during the balancing operation to track the time at which the rotor rotates while the balancing mechanisms 11, 12 are in the unlocked state. After a minimum period of time in which the rotor rotates while the balancing mechanisms 11, 12 are in the unlocked state, the balancing members 11, 12 are the triggered (either by an operator or automatically by the timer) to return to the locked position.

[0052] Another embodiment of a self -balancing rotor 105 is shown in Figures 12-13. The components shown in Figures 12-13 that are analogous to those of Figures 1-11 are designated by the corresponding reference number of Figures 1-11 plus "100" (e.g., part 10 becomes 110). The first locking device 125 includes a first locking surface 131 of a channel outer sidewall 121 (or "locking disk") that is capable of being moved laterally into the locked and unlocked positons. A biasing element 155 (e.g., a spring, as shown, or an elastomeric element or the like) biases the outer sidewall 121 in the locked position.

[0053] An actuator (e.g., a pneumatic or hydraulic cylinder, as shown) includes a cylinder 137A and a piston 137B within the cylinder that are used to move the sidewall 121 to the unlocked position. The actuator 137 is pressured through a zerk 140 to flow fluid (e.g., air, grease, oil or the like) into chamber 156. The fluid forces the chamber 156 to expand and causes the piston 137B to exert a force against biasing element 155. Once the force of the piston 137B exceeds the force of the biasing element 155, the outer sidewall 121 begins to move and increase the channel width to allow the balancing members 117 to move within the channel 113.

[0054] The fluid pressure also exerts a force on the cylinder 137A. This force is translated through a second spring 163 to the rotor shaft 143. The shaft 143 moves to cause the second locking device (which may be the same as the locking mechanism 62 shown in Figure 10) to move to the unlocked position. The locking mechanism 125 returns to the locked position by bleeding fluid from the system (e.g., from zerk 140 or another bleed opening) over a period of time. Spring 163 acts to slowly push cylinder 137A to its original position as fluid purges. In this manner the actuator and fluid hold the locking device in the unlocked position for a period of time to allow the balancing member 117 of the first balancing mechanism 111 to balance the rotor 105 before returning to the locked positon.

[0055] Another embodiment of a self -balancing rotor 205 is shown in Figure 14. The components shown in Figure 14 that are analogous to those of Figures 1-11 are designated by the corresponding reference number of Figures 1-11 plus "200". The first balancing mechanism 211 includes a first channel 213 and balancing members 217. The balancing members 217 are metal. The locking device 225 includes several electromagnets 290 embedded therein to adjust the locking device between an unlocked state (i.e., unpowered state) in which the electromagnets do not limit movement of the balancing members 217 in the channel and a locked state (i.e., powered state) in which the balancing members are prevented from moving due to repulsion caused by the

electromagnets 290. The rotor 205 includes an identical second balancing mechanism and a second locking device at the second end of the rotor 205. In other embodiments, the polarities of the electromagnets 290 are reversed such that the locked state is achieved in the unpowered state, while the unlocked state would be achieved in a powered state.

[0056] It should be noted that while the locking devices of embodiments of the present disclosure may be described and/or shown as working upon a pair of balancing mechanisms, embodiments of the locking devices may also be used in a rotor system having a single balancing member as well as systems having two balancing members unless stated otherwise .

[0057] While the rotor may be shown or described as being a cylindrical rotor, in other embodiments and as shown in Figures 16-17, a disk-type rotor 305 may be used. The components shown in Figures 16-17 that are analogous to those of Figures 1-11 are designated by the corresponding reference number of Figures 1-11 plus "300". The self- balancing rotor 305 includes a rotating member 308 and a balancing mechanism 311. The balancing mechanism 311 includes a channel 313 and balancing members 317 within the channel 313. The rotor 305 includes a locking device 325 having a locking surface 331 that is the sidewall of the channel 313. The locking surface 331 is capable of moving laterally into a locked and unlocked position. A biasing element 355 (e.g., a spring, as shown) biases the locking surface 331 in the locked position. [0058] An actuator 337 (e.g., a pneumatic or hydraulic cylinder, as shown) are used to overcome the clamping force of the biasing element 355 and move the locking surface 331 to the unlocked position. The actuators 337 may be pressurized by a fluid transfer system 360 (Fig. 17) . The fluid transfer system 360 adds or removes fluid (e.g., air, grease, oil or the like) to the actuator 337 to cause the locking surface 331 to move between the locked and unlocked states. As shown in the embodiment illustrated in Figure 17, the fluid transfer system 360 may include a fluid fitting 364 attached to a slip ring 366. In the embodiment illustrated in Figure 16, fluid may bleed from the balancing mechanism 311 to allow the locking device 325 to return to the locked state.

[0059] Compared to conventional cylindrical rotors, the cylindrical rotors of the present disclosure have several advantages. Use of two balancing mechanisms with a balancing mechanism being positioned toward each end of the rotor allows the cylindrical rotor to be balanced across its length. The two balancing mechanisms may be used, for example, as a two-plane automatic balancer of a cylindrical rotor for a material comminuting or reducing apparatus. The balancing mechanisms may be configured (i.e., size and shape of balancing members, number of balancing members, radius of circular channel, axial positions of channels) to withstand external impacts that are characteristic of comminuting apparatus and in particular apparatus with internal

combustion engines. Use of locking devices which lock the balancing members in place allows the rotor to remain balanced through frequent acceleration and deceleration and through the various external impacts that are encountered in rotors of comminuting apparatus (e.g., forestry mowers, bale processors, horizontal or tub grinders and surface excavation machines) . Actuators allow the locking mechanisms to be adjusted by the user into locked and unlocked states. Use of cylindrical balancing members increases the contact surface of the balancing members with the channel which provides damping for the balancing members and may increase the mass of the balancing members with a given channel due to the geometry of the balancing members.

[0060] The balancing mechanisms allow static imbalance of the rotor to be corrected as the balancing members may move to the same counter-balance location with zero phase difference between the two ends. The mass added by the members reduces the off-set of the center of mass of the rotor while the principle axis remains parallel to (or overlaid with) the axis of rotation of the rotor. The balancing mechanisms also allow dynamic imbalance of the rotor to be corrected as the balancing members of both balancing mechanisms will move to different counter-balanced locations which allows the principle axis of the rotor to be corrected to parallel to the axis of rotation and the location of the center of mass of the rotor will be shifted to minimize any initial offset.

[0061] As used herein, the terms "about,"

"substantially," "essentially" and "approximately" when used in conjunction with ranges of dimensions, concentrations, temperatures or other physical or chemical properties or characteristics is meant to cover variations that may exist in the upper and/or lower limits of the ranges of the properties or characteristics, including, for example, variations resulting from rounding, measurement methodology or other statistical variation. [0062] When introducing elements of the present disclosure or the embodiment (s) thereof, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements. The terms "comprising,"

"including," "containing" and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. The use of terms indicating a particular orientation (e.g., "top", "bottom", "side", etc.) is for convenience of description and does not require any particular orientation of the item described.

[0063] As various changes could be made in the above constructions and methods without departing from the scope of the disclosure, it is intended that all matter contained in the above description and shown in the

accompanying drawing [s] shall be interpreted as illustrative and not in a limiting sense.