US20150167492A1

US20150167492A1 - Balancer

Info

Publication number: US20150167492A1
Application number: US14/573,533
Authority: US
Inventors: Samuel Collette; David Johnson; Paul Schreier; Devyani Sharma; Andrew Smith
Original assignee: Red Tail Hawk Services Inc
Current assignee: Red Tail Hawk Services Inc
Priority date: 2013-12-17
Filing date: 2014-12-17
Publication date: 2015-06-18
Also published as: WO2015095321A1

Abstract

A rotating object balancer may include an insert configured for securing to an object and having a chamber for placement of balancing elements and a curable solution, a rotational system configured to rotate the object at high-speed, a monitoring system for monitoring vibrations of the object rotating at high-speed, and a curing tool configured for curing the curable solution when the object has reached a balanced state. A method of balancing may be performed by the balancer and a balanced object may be created by the balancer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional Application No. 61/917,193 filed on Dec. 17, 2013 entitled Balancer, the content of which is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present disclosure relates generally to balancing. More particularly, a system and method for balancing objects that rotate by adjusting the moment of inertia of the objects is described. Still more particularly, the present disclosure relates to dynamically balancing rotating objects such as propellers, fans, wheels, hubs, motors, sheaves, pulleys, and other rotating objects.

BACKGROUND

The Federal Aviation Administration (FAA) is mandated to open U.S. airspace for the commercial use of unmanned aerial vehicles (UAVs) by 2015. It is expected that any company or individual that wishes to use UAVs commercially will need to fill out a safety flight operations certificate (SFOC) that will need to be approved by the FAA each time they plan on operating a UAV. It is anticipated that the SFOC document will include a flight plan and certification that the UAV meets all safety requirements defined by the FAA. It appears that one requirement will be that all propellers are dynamically balanced to limit vibration in the aircraft. Vibration due to propeller imbalance limits the effectiveness of on-board instrumentation (i.e., a high resolution camera would take unclear photos and video) and possibly causes mechanical failure of the aircraft.
Current methods for balancing propellers include suspending the propellers at their center and allowing them to hang vertically. Where the propeller has a tendency to turn or rotated tape may be added to the propeller to avoid disrupting the aerodynamics of the propeller while attempting to rely on the weight of the tape to balance the propeller. The propeller may also be hung horizontally and where the propeller has a tendency to turn or rotate, additional tape may be added. In addition, vibrations in a propeller may be monitored or sensed during rotation and then the propeller may be brought to a stop to adjust the propeller. This process may be reiterated until a balanced propeller is achieved. A similar approach is often used for balancing tires in the automotive industry, for example. Given the anticipated large number of UAV and other propellers that are to be in services as early as 2015, current approaches to balancing propellers or other objects are unduly time consuming and not cost effective.

BRIEF SUMMARY OF THE INVENTION

In one or more embodiments, a rotating object balancer may include an insert configured for securing to an object and having a chamber for placement of balancing elements and a curable solution. The balancer may include a rotational system configured to rotate the object at high-speed. The balancer may also include a monitoring system for monitoring vibrations of the object rotating at high-speed. The balancer may also include a curing tool configured for curing the curable solution when the object has reached a balanced state.
In one or more embodiments, a method of balancing an object may include arranging balancing elements on the object such that the balancing elements are free to move within a region. The method may also include rotating the object at high-speed and monitoring the object for a balanced condition. The method may also include fixing the position of the balancing elements when the object is in a balanced condition and while the object is rotating.
In one or more embodiments, a rotationally balanced object may include a body portion and a cavity arranged within the body portion. The object may also include a balancing element arranged within the cavity portion and a cured or curable substance arranged within the cavity. The cured or curable substance may at least partially surround the balancing element and be configured for securing the position of the balancing element when the substance is in a cured state.

BRIEF DESCRIPTION OF FIGURES

FIG. 1A is an exploded perspective view of a propeller with an insert adapted for balancing the propeller, according to one or more embodiments.

FIG. 1B is a perspective view of the insert of FIG. 1A, according to one or more embodiments.

FIG. 1C is a front view of the insert of FIG. 1A, according to one or more embodiments.

FIG. 1D is a side view of the insert of FIG. 1A, according to one or more embodiments.

FIG. 2A is a front view of a balancing assembly for balancing a propeller such as that shown in FIGS. 1A-1D or other object, according to one or more embodiments.

FIG. 2B is a partially exploded view of the balancing assembly of FIG. 2A, according to one or more embodiments.

FIG. 3A is a perspective view of a universal switch assembly for coupling the propeller to a motor and allowing for relative movement therebetween, according to one or more embodiments.

FIG. 3B is a top view of the universal switch assembly of FIG. 3A, according to one or more embodiments.

FIG. 3C is a side view of the universal switch assembly of FIG. 3A, according to one or more embodiments.

FIG. 4A is a perspective view of a drive receiving portion of the assembly of FIG. 3A, according to one or more embodiments.

FIG. 4B is a top view of the drive receiving portion of FIG. 4B, according to one or more embodiments.

FIG. 4C is a side view of the drive receiving portion of FIG. 4C, according to one or more embodiments.

FIG. 4D is a side view of the drive receiving portion of FIG. 4D, according to one or more embodiments.

FIG. 5A is a perspective view of a central block portion of the assembly of FIG. 3A, according to one or more embodiments.

FIG. 5B is a top view of the central block portion of FIG. 5A, according to one or more embodiments.

FIG. 5C is a side view of the central block portion of FIG. 5A, according to one or more embodiments.

FIG. 6A is a perspective view of a motor plate for securing to the motor and the universal switch, according to one or more embodiments.

FIG. 6B is a top view of the motor plate of FIG. 6A, according to one or more embodiments.

FIG. 6C is a side view of the motor plate of FIG. 6A, according to one or more embodiments.

FIG. 7A is a perspective view of a bottom/top plate, according to one or more embodiments.

FIG. 7B is a top view of the bottom/top plate of FIG. 7A, according to one or more embodiments.

FIG. 8A includes a perspective view of a block, according to one or more embodiments.

FIG. 8B is a top view of the block of FIG. 8A, according to one or more embodiments.

FIG. 9A is a perspective view of a bracket for securing to the block, according to one or more embodiments.

FIG. 9B is a top view of the bracket of FIG. 9A, according to one or more embodiments.

FIG. 9C is a side view of the bracket of FIG. 9A, according to one or more embodiments.

FIG. 10A is a clamp assembly for securing the cage assembly, according to one or more embodiments.

FIG. 10B is a top view of the clamp assembly of FIG. 10A, according to one or more embodiments.

FIG. 10C is a side view of the clamp assembly of FIG. 10A, according to one or more embodiments.

FIG. 11A is a perspective view of a large spring, according to one or more embodiments.

FIG. 11B is an end view of the spring of FIG. 11A, according to one or more embodiments.

FIG. 12A is a perspective view of another spring, according to one or more embodiments.

FIG. 12B is an end view of the spring of FIG. 12A, according to one or more embodiments.

FIG. 12C is a side view of the spring of FIG. 12A, according to one or more embodiments.

FIG. 13A is a perspective view of a fan cage bottom, according to one or more embodiments.

FIG. 13B is a top view of the fan cage bottom of FIG. 13A, according to one or more embodiments.

FIG. 13C is a side view of the fan cage bottom of FIG. 13A, according to one or more embodiments.

FIG. 14A is a perspective view of a fan cage top, according to one or more embodiments.

FIG. 14B is a top view of the fan cage top, according to one or more embodiments.

FIG. 14C is a side view of the fan cage top, according to one or more embodiments.

FIG. 15A is a perspective view of an accelerometer for measuring the vibration of the rotating propeller or other object, according to one or more embodiments.

FIG. 15B is a top view of the accelerometer, according to one or more embodiments.

FIG. 16 shows a flow chart including operations for balancing a rotating object such as a propeller, according to one or more embodiments.

DETAILED DESCRIPTION

The present application, in one or more embodiments, includes a discussion of a propeller and/or insert adapted for dynamic balancing in addition to a system and method for balancing propellers or other rotating objects. The propeller or other rotating object may include a hollow chamber with free moving weights arranged therein. In the case of a propeller, the chamber may be arranged in or around the hub of the propeller. The propeller with the chamber may be rotated at high speeds and the free movement of the weights may allow the weights to naturally find a balanced arrangement or position within the chamber. The chamber may also include a curable medium in which the free moving weights are suspended. While the propeller is in motion and in a balanced condition, the curable medium may be cured such as with an ultraviolet light device, for example.
The present application is, thus, inventive and advantageous for several reasons. First, while the moment of inertia of a rotating object may be more drastically modified by adjusting the mass closer to the perimeter of the rotating object, the present approach adjusts the mass more proximate to the axis of rotation with surprisingly effective results. In addition, the present application moves away from manual static balancing and iterative dynamic balancing and employs a single iteration dynamic approach. It does so by first employing an automatic balancing approach that allows the modified propeller to find a balanced condition. Secondly, it provides a way to fix that balanced condition while the propeller is rotating. As such, the present device and method provides an extremely efficient approach to balancing of propellers or other rotating objects. It is to be appreciated that while the focus of the present application may be on propellers, a similar approach may be provided for balance a wide range of objects including wheels, rims, pulleys, sheaves, motors, spindles, armatures, and other rotating and/or non-rotating objects.
FIG. 1A shows a propeller 100 with an insert 102 configured for balancing the propeller 100. The insert 102, as shown in more detail in FIGS. 1A-1C, may be adapted, as shown, for securing to the hub portion 104 of the propeller 100 and may include an outer circumference substantially matching that of the hub 104. The insert 102 may include a body portion 102A having an end cap 106, a substantially annular outer wall 108, and a substantially annular inner wall 110 spaced from the outer wall 108 and defining an annular chamber 112 therebetween. The annular inner wall 110 may extend from the end cap 106 upward beyond the height of the annular outer wall 108 so as to engage a bore 114 in the propeller. The insert 102 may also include a washer 102B for sleevably engaging the inner wall 110 and positioning against an end of the outer wall 108 so as to seal the chamber 112. The chamber 112 may be provided with one or more balancing elements 116 such as ball bearings that are generally free to move about the chamber 112. The chamber 112 may also be provided with a curable medium that substantially surrounds all or a portion of the balancing elements 116 while allowing them to move substantially freely through the medium within the chamber 112. The curable medium may be curable such as by exposure to ultraviolet light, such that the position of the ball bearing may be selectively fixed by curing the medium at a desired time. The insert 102 may be secured to a rotating shaft together with the propeller 100 by extending a flanged shaft through the bore in the insert and the bore 114 in the propeller. It is to be appreciated that in some embodiments, the insert 102 may include a key or keyway for engaging the propeller 100 in a particularly radial orientation such that the insert 102 and the propeller 100 may be detached and reattached in a particular orientation. In other embodiments, a key or keyway may be omitted. In still other embodiments, the insert 102 may be adhered to the propeller 100 to resist relative rotational motion that may upset the balanced condition of the propeller 100 once the medium has been cured and the position of the balancing element 116 has been established. It is to be appreciated that while a curable medium curable by ultraviolet light has been described, most any medium that may be curable in some fashion during balanced motion of the rotation object may be used. For example, solutions curable by heat or by chemical mixing, such as epoxy, may also be used.
It is to be further appreciated that while a particular rotating object in the form of a propeller 100 has been described, most any rotating object may be provided with a similar balancing feature. In some embodiments, for example, a wheel or other rotating object may have an insert 102 similar to the one described. In other embodiments, a more permanent portion of the rotating object may be dedicated for balancing. That is, the mentioned chamber 112 may be a part of the object itself rather than part of an insert 102 for use with or attachment to the object. Still further, while the presently described insert 102 is arranged near the center of rotation of the object, chambers 112 and balancing elements 116 may be positioned more radially outward than described.
Turning now to FIG. 2A and 2B, a system 200 for balancing rotating objects is shown. As sown, the system 200 may be configured to securely and safely hold a rotating object while, at the same time, allowing the object to move freely with several degrees of freedom so as to allow the object to find a natural balanced condition when it is rotated. In some embodiments, as shown, the system 200 may include base clamp portion 202, a base 204, a bracket 206, a universal switch assembly 208, a cage assembly 210, and a curing tool 212.
As shown in FIGS. 3A-3C, a universal switch assembly 208 is shown. The universal switch assembly 208 may be adapted to isolate motor and propeller vibrations such that the balanced condition of the propeller 100 is affected relatively little by vibrations in the motor or support system. That is, the balancing elements 116 may be intended to balance the propeller 100 apart from vibrations that may be induced by other aspects of the balancing system 200 and/or an aircraft on which the propeller 100 is to be used. Accordingly, the universal switch assembly 208 may allow for free movement of the motor in an x and y direction relative to the rotating propeller 100 thereby avoiding imparting vibrations in those directions to the propeller 100. As may be appreciated from a review of FIGS. 3A-3C, the switch 208 may include a receiver portion 214, a central portion 216, and a top portion 218. The central portion 216 may be substantially free to pivot about a first axis 220 relative to the receiver portion 214 and the top portion 218 may be substantially free to pivot about a second axis 222 relative to the central portion 216. The first and second axes 220, 222 mentioned may be substantially perpendicular to a vertical or central axis 224 of the receiver portion 214 and the first and second axes 220, 222 may be substantially perpendicular to one another. Without more, the switch assembly 208 shown in FIG. 3C, for example, may be substantially free to collapse by pivoting motion about one of the first axis 220 or second axis 222 or both.
As shown in FIG. 4A, the receiver portion 214 is shown in more detail and may include a receiving bore 226 extending upwardly into a bottom portion of the receiver portion 214 for receiving a drive shaft or other shaft such as a shaft extending upwardly from the motor plate picture in FIGS. 6A-6C. The receiver portion 214 may be otherwise cylindrically shaped having a vertical axis 224 and may include a pair of straddling tabs 228 extending upwardly from a top surface thereof. The straddling tabs 228 may each include a bore 230 extending therethrough, the bores together defining an axis 220 (i.e., the first axis. 220 above) substantially perpendicular to the vertical axis 224.
As show in FIG. 5A, a central block or portion 216 is shown. The central block or portion 216 may be substantially rectangular in shape and may have a pair of pegs 232 on a lower portion thereof configured and arranged for insertion into the bores 230 of the straddling tabs 228 of the receiver portion 214 and, thus, along the first axis 220. The central block or portion 216 may also include a pair of pegs 234 on an upper portion thereof configured and arranged substantially perpendicularly to the pegs 232 on the lower portion of the block 216. These pegs 234 may be spaced apart from the first pegs 232 by a distance substantially equal to the distance between the first axis 220 and the second axis 222.
While not show in detail, a top portion 218 may be provided that is similar to the receiver portion 214 except that the top portion 218 may have a protruding lug or shaft 236 for engaging and/or supporting a rotating object in lieu of having a receiving bore 226. However, like the receiver portion 214, the top portion 218 may include a pair of straddling tabs that each include a bore for receiving the pegs on the upper portion of the central block 216. The top portion may be configured to be arranged in an inverted position relative to the receiver portion 214 for the universal switch 208.
FIGS. 6A-6C show a motor plate 240 for holding the bionic switch 208 in place on the motor. As shown, the motor plate 240 may be mountable to a rotating motor via one or more bores 242. The motor plate 240 may include a drive pin 244 configured for insertion into the receiver portion 214 of the switch 208 so as to transfer rotational motion from a motor to the switch 208.
FIGS. 7A and 7B show bottom and top plates 246. The bottom and top plates 246 may include a keyway 248 for slidably engaging the drive pin 244 on the motor plate 240 and arrest or prevent rotational motion of the motor plate 240 unless/until the bottom and top plate 246 is translated such that the drive pin 244 is positioned in the circular portion of the keyway 248 thereby allowing rotational motion of the drive pin.
FIGS. 8A and 8B show a block 250 for holding the bottom plate 246 and for housing between the bottom cage 210B and the clamp 202. The block 250 may be attached to the bracket 206 shown in FIGS. 9A-9C with screws or other fasteners, for example. The bracket 206 in FIGS. 9A-9C may be secured to the block 250 as mentioned and may support the bottom cage 210B shown in FIGS. 13A-13C. The bracket 206 may be configured to extend upwardly from the block portion 250 around any rotating portions of the assembly 200 and including a bore 252 for passing through a rotating shaft. The bracket 206 may then converge toward a center of the system to the bore 252 and may include mounting areas and holes for securing the bottom cage.
FIGS. 10A-10C show a clamp 202 for securing the system 200 in place. The clamp 202 may include a translatable portion 254 driven by a drive or set screw 256 such that a bulkhead or ram 254 may be driven against the block 250 or other aspect of the system 200 and secure the system within the clamp 202 in the space 260 between the ram 254 and the opposing wall 258.
FIGS. 11A-11B and FIGS. 12A-12C show securing springs 262, 264 for balancing the motor and/or propeller 100 on the universal switch assembly 208 within the cage 210. That is, as mentioned, without more, the switch portion 208 of the system 200 may be designed to collapse or buckle such that lateral affects are not imparted on the propeller 100 as it attempts to find a balanced condition. Accordingly, the springs 262, 264 shown may be provided to maintain the switch 208 in an upright position without imparting such lateral loads on the switch 208 that would affect the balanced condition of the propeller 100.
FIGS. 13A-13C and FIGS. 14A-14C show a fan cage bottom 210B and top 210A, respectively. The fan cage 210 may be positioned to enclose the rotating object or propeller 100 so as to prevent injury to personnel, users, or technicians using the system.
FIGS. 15A-15C show an accelerometer 266 for gauging changes in accelerations in the x, y, and z directions. The accelerometer 266 may be secured to the motor base plate 240 and may sense the motions being imparted on the motor plate 240 by the propeller 100 and, thus, may be used to analyze the balanced or unbalanced condition of the propeller 100.
In one embodiment, the clamp 202 may secure the block 250 in place. The top/bottom plates 246 may be secured thereto with differing orientations such that the square extrude on the universal switch 208 may be inserted into the square opening formed by the crossing rectangular slots. The bracket 206 may be secured to the block 250 through the openings in the corners of the top/bottom plate 246. The bottom cage 210B may be secured to the bracket 206 and the female end of the universal switch 208 may extend upward through the bracket 206 and into the bottom of the cage 210. The motor bracket 240 may be secured to the female end of the universal switch 208 by inserting the rectangular extrude into the female receiver 226 in the switch 208. Springs 262, 264 may be provided to stabilize the switch 208 within the cage 210. The motor may be secured to the motor bracket 240 with screws and the propeller 100 may be mounted on the drive shaft of the motor. The upper portion of the cage 210A may be positioned on the lower portion 210B to close the system. Still other arrangements of the several elements of the system may be provided.
As mentioned above, the device may be used to balance a propeller or other object or rotating object by performing a method (300). FIG. 16 shows a series of method steps that may be performed with the above described device to balance a propeller 100 or other object. It is to be appreciated that while the several operations are shown in a flow chart, one or more of the operations may be performed out of order and the balancing operation may still be suitably completed. As such, nothing about FIG. 16 should be used to limit the present application to the particular order shown. Still further any portion of the method (300) may be performed in isolation from the remaining portions of the method (300).
As shown in FIG. 16, the insert may be provided with balancing elements by placing the balancing elements in the chamber of the insert. (302) The insert may also be provided with a curable medium such as, for example, a resin (304) and the chamber may be closed (306). The insert 102 may be mounted to the propeller 100 and secured to resist relative rotational motion between the insert 102 and the propeller 100. The propeller 100 and insert 102 may then be mounted on the balancing system (308) and rotated (310) at a relatively high speed such as approximately 7000 RPM to approximately 12000 RPM or approximately 8000 RPM to approximately 11000 RPM or approximately 9000 RPM to approximately 10000 RPM. The rotating propeller or object may be monitored for a balanced condition based on vibrations readings and/or accelerations. (312) A balanced condition may be identified when vibrations and/or accelerations are within a selected range. (314) With the propeller rotating in a balanced condition due to the natural propagation of the balancing elements, the resin may be cured by, for example, exposing the insert to ultraviolet light while the propeller continues to rotate. (316) The propeller or object may be stopped (318) and removed from the balancer. (320) Other types of curable mediums and other curing operations may be used such as heating/cooling and the like.
The balanced propeller may be measured to identify the levels of imbalance that remain. These measurements may be made throughout a wide range of rotational speeds to identify imbalance amounts at various speeds. A balance report may be generated for purposes of maintaining the report with the propeller such that a later user may understand the balance properties of the propeller. It is to be appreciated that identification elements such as bar codes, QR codes, RFID tags and the like may also be included as part of the propeller and the balance report may be saved to a database and associated with identification element of the propeller allowing easy and secure access to balance information for large number of balanced propellers or objects.
While the present disclosure has been described with reference to various embodiments, including preferred embodiments, it will be understood that these embodiments are illustrative and that the scope of the disclosure is not limited to them. Many variations, modifications, additions, and improvements are possible. More generally, embodiments in accordance with the present disclosure have been described in the context of particular embodiments. Functionality may be separated or combined in blocks differently in various embodiments of the disclosure or described with different terminology. These and other variations, modifications, additions, and improvements may fall within the scope of the disclosure as defined in the claims that follow.

Claims

What is claimed is:

1. A rotating object balancer, comprising:

an insert configured for securing to an object and having a chamber for placement of balancing elements and a curable solution;

a rotational system configured to rotate the object at high-speed;

a monitoring system for monitoring vibrations of the object rotating at high-speed; and

a curing tool configured for curing the curable solution when the object has reached a balanced state.

2. The balancer of claim 1, wherein the curing tool comprises an ultraviolet light emitting device.

3. The balancer of claim 2, wherein the curing tool comprises a heating element.

4. The balancer of claim 1, wherein the object is a propeller.

5. The balancer of claim 4, wherein the insert is configured for engaging the hub of the propeller.

6. The balancer of claim 1, wherein the rotational system comprises a universal switch configured to isolate vibrations from a drive system so as to avoid affecting vibration of the object.

7. The balancer of claim 6, wherein the universal switch comprises a drive receiving portion, a central portion pivotable relative to the drive receiving portion about a first axis, and a top portion pivotable relative to the central portion about a second axis.

8. The balancer of claim 7, wherein the drive receiving portion defines a longitudinal axis and the first axis and second axis are substantially perpendicular to the longitudinal axis.

9. The balancer of claim 8, wherein the first and second axes are substantially perpendicular to one another.

10. The balancer of claim 9, wherein further comprising a cage for surrounding the object during rotation.

11. The balancer of claim 1, wherein the chamber is substantially annular in shape and includes a substantially round cross-section.

12. The balancer of claim 11, wherein the balancing elements comprise ball bearings.

13. The balancer of claim 11, wherein the balancing elements are surrounded by the curable solution within the chamber.

14. The balancer of claim 13, wherein the curable solution is curable by exposure to ultraviolet light.

15. A method of balancing an object, comprising:

arranging balancing elements on the object such that the balancing elements are free to move within a region;

rotating the object at high-speed;

monitoring the object for a balanced condition; and

fixing the position of the balancing elements when the object is in a balanced condition and while the object is rotating.

16. The method of claim 15, wherein the region comprises a chamber and arranging balancing elements on the object comprises placing the objects in a chamber.

17. The method of claim 16, wherein fixing the position of the balancing elements comprises exposing the object to ultraviolet light.

18. A rotationally balanced object, comprising:

a body portion;

a cavity arranged within the body portion;

a balancing element arranged within the cavity portion; and

a cured or curable substance arranged within the cavity at least partially surrounding the balancing element and configured for securing the position of the balancing element when the substance is in a cured state.

19. The object of claim 18, wherein the substance is curable using ultraviolet light.

20. The object of claim 19, wherein the substance is curable using heat.

21. The object of claim 18, wherein the substance is a two part material curable by mixing.

22. The object of claim 18, wherein the body portion comprises a base portion and an insert or attachment.

23. The object of claim 18, wherein the cavity is arranged in the insert or attachment.