WO2010036952A2

WO2010036952A2 - Magnetically activated wheel lock mechanism

Info

Publication number: WO2010036952A2
Application number: PCT/US2009/058468
Authority: WO
Inventors: John C. Mckay
Original assignee: Gatekeeper System, Inc.
Priority date: 2008-09-25
Filing date: 2009-09-25
Publication date: 2010-04-01
Also published as: WO2010036952A3

Abstract

Embodiments of a wheel and a brake mechanism for use with a non-motorized cart such as a shopping cart are disclosed. In some embodiments the wheel has a hub having a plurality of first engagement features, and the brake mechanism includes at least one second engagement feature that can be moved between an unactuated position and an actuated position. In the unactuated position, the second engagement feature does not engage any of the plurality of first engagement features on the hub, and in the actuated position, the second engagement feature operatively engages at least one of the first engagement features in order to provide a braking force that locks the wheel. A magnetically-activated trigger maintains the second engagement feature in the unactuated position. In response to a triggering magnetic field, the trigger is released and allows the second engagement feature to move from the unactuated position to the actuated position.

Description

MAGNETICALLY ACTIVATED WHEEL LOCK MECHANISM

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 61/100,227, filed September 25, 2008, entitled "MAGNETICALLY ACTIVATED WHEEL LOCK MECHANISM₅" which is hereby incorporated by reference herein in its entirety.

BACKGROUND Field

[0002] This application relates to a magnetically activated wheel lock mechanism for a wheel for a non-motorized vehicle including, but not limited to, a shopping cart. Methods of operation for embodiments of the wheel lock mechanism are provided. Description of Related Art

[0003] A variety of commercially available cart containment systems exist for deterring the theft or movement of carts into undesirable or unsafe areas. For example, the cart may include a wheel brake mechanism that inhibits or prevent movement of the cart when the brake is actuated (e.g., by inhibiting rotation of a wheel of the cart). In one example containment system for a retail store, a wire is embedded in the pavement of the store parking lot to define an outer boundary of an area in which shopping cart use is permitted. A signal generator is used to transmit an electromagnetic signal through the wire to provide an indication of the outer boundary. One or more wheels of the shopping carts are configured with a wheel brake mechanism. When a shopping cart is moved over the outer boundary, a sensor in or near the shopping cart wheel detects the electromagnetic signal in the wire, and in response, the wheel brake mechanism is actuated, inhibiting movement of the cart. For example, the actuated wheel brake mechanism may substantially prevent rotation of the wheel (e.g., by locking the wheel against rotation) or may apply a braking force that makes it difficult for the wheel to rotate.

[0004] Such a system advantageously deters theft (and/or movement of carts into undesirable and/or unsafe areas), because a user will have to drag (or carry) the cart once the wheel has been braked, hi some implementations, to unbrake the wheel, an authorized attendant may use a handheld remote control, a key, or other unlocking mechanism to provide an unlock signal to the wheel brake mechanism, thereby permitting the cart to be rolled back to the retail location.

SUMMARY

[0005] Embodiments of a magnetically-activated wheel and a brake mechanism for use with a non-motorized cart such as, e.g., a shopping cart are disclosed. In some embodiments the wheel has a hub having a plurality of first engagement features, and the brake mechanism includes at least one second engagement feature that can be moved between an unactuated position and an actuated position. In the unactuated position, the second engagement feature does not engage any of the plurality of first engagement features on the hub, and in the actuated position, the second engagement feature operatively engages at least one of the first engagement features in order to provide a braking force that locks the wheel. A magnetically-activated trigger maintains the second engagement feature in the unactuated position. In response to a triggering magnetic field, the trigger is released and allows the second engagement feature to move from the unactuated position to the actuated position.

[0006] hi some embodiments, the wheel is mounted on an axle in a caster. The brake mechanism can be mounted on the axle (and may be at least partially supported by the caster), adjacent the wheel, so that the brake mechanism does not rotate when the wheel rotates. In some embodiments, the wheel and the brake mechanism are mounted on the axle between two arms of the caster. In some embodiments, the caster is configured to rotate in a full circle (around a leg of the cart) so that when the cart is moved, the caster rotates such that the brake mechanism is disposed toward a centerline of the cart.

[0007] Embodiments of a wheel assembly for use with a human-propelled cart are provided. In some embodiments, the wheel assembly comprises a caster having an end configured to be attached to the human-propelled cart. The caster is configured to support an axle. The wheel assembly also comprises a wheel that is rotatable about the axle. The wheel comprises a hub having a plurality of engagement features. The wheel assembly also comprises a lock assembly that is mountable on the axle adjacent the wheel. The lock assembly can be configured not to rotate about the axle. The lock assembly comprises a lock plate configured to move in a direction perpendicular to the axle between an unlocked position and a locked position. The lock plate comprises a lock member that is configured to engage at least one of the plurality of engagement features of the hub when the lock plate is in the locked position. The lock assembly also comprises a trigger configured to maintain the lock plate in the unlocked position. The trigger is actuatable to release the lock plate in response to a triggering magnetic field. The lock assembly also comprises a spring-loaded driver configured to move the lock plate between the unlocked position and the locked position when the lock plate is released by the trigger.

[0008] Embodiments of a cart containment system for use with non- motorized, wheeled carts are provided. The non-motorized wheeled carts may include shopping carts. In some embodiments, the cart containment system comprises a non- motorized cart having at least one wheel assembly that comprises a wheel and a brake mechanism. The brake mechanism is actuatable to brake rotation of the wheel in response to a triggering magnetic field. A magnet is configured to provide the triggering magnetic field. The magnet can be disposed in, on, or under a surface over which the cart can travel. The magnet may be a permanent magnet, an electromagnet, or a combination thereof. The magnet may comprise a plurality of magnets, magnetic strips, etc. The brake mechanism comprises a brake member that can move between a first position in which the brake member does not contact an engagement surface of the wheel to a second position in which the brake member contacts the engagement surface of the wheel to cause a braking force to be applied to the wheel. The brake mechanism can be configured to move the brake member from the first position to the second position when the wheel assembly of the cart passes over the magnet.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Specific embodiments of the disclosure will now be described with reference to the drawings summarized below. These specific embodiments are intended to illustrate, and not limit, the scope of the disclosure.

[0010] Figure 1 schematically illustrates an embodiment of a wheel assembly.

[0011] Figures 2A and 2B are front and back views, respectively, of an embodiment of a lock assembly.

[0012] Figures 3A and 3B schematically illustrate an embodiment of a wheel lock mechanism and a triggering mechanism.

[0013] Figure 4 schematically illustrates an embodiment of a safety mechanism that is optionally usable with embodiments of the wheel lock mechanism. [0014] Figures 5A and 5B schematically illustrate an embodiment of a reset key usable with a reset mechanism and/or a safety mechanism.

[0015] Figures 6A and 6B schematically illustrate an embodiment of the lock mechanism in an actuated position (Fig. 6A) and an unactuated position (Fig. 6B).

[0016] Figure 7 is an exploded view that schematically illustrates an embodiment of a wheel assembly.

[0017] Figure 8A schematically illustrates an embodiment of a wheel and wheel lock mechanism (inside a housing) that can move over a surface (not shown) having an embedded magnet. The wheel lock mechanism is unactuated in Figure 8 A.

[0018] Figure 8B schematically illustrates the wheel and wheel lock mechanism of Figure 8A as they pass over the embedded magnet, which actuates the wheel lock. The housing shown in Figure 8A has been removed to illustrate the wheel lock mechanism in an actuated position.

[0019] Figure 9 schematically illustrates the wheel lock mechanism of Figure 8 A in the actuated position.

[0020] Figure 10 schematically illustrates a portion of an embodiment of a lock mechanism in an actuated state in which tabs of the lock mechanism are urged between raised inserts on a wheel hub to substantially inhibit rotation of the wheel. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0021] Embodiments of the magnetically activated wheel lock mechanism described herein advantageously may be used to deter theft and/or inhibit movement of carts into unsafe or undesirable areas. Embodiments of the magnetically activated wheel lock mechanism described herein may be used alone or in combination with other cart containment systems (e.g., systems using a wire embedded in pavement or flooring). For example, embodiments of the wheel lock mechanism can be used with the anti-theft vehicle system described in U.S. Patent No. 6,362,728, issued March 26, 2002, titled "Anti-Theft Vehicle System," which is hereby expressly incorporated by reference herein in its entirety. The present discussion is not intended to suggest that the wheel lock mechanism is limited to shopping carts or cart containment applications. Embodiments of the disclosed wheel brake mechanism may be used with a wide range of non-motorized vehicles including, but not limited to, human-propelled vehicles and carts, warehouse carts, industrial carts, luggage carts, baggage carts, trolleys, medical equipment carts, wheelchairs, wheeled stretchers, strollers, beds, and so forth. Further, although some embodiments of the wheel brake mechanism may lock the wheel such it is substantially prevented from rotating about a wheel axis, other embodiments of the mechanism may provide a braking force such that the wheel, although not locked into place, is substantially inhibited from rotating about the wheel axis. Example Wheel and Hub Assembly

[0022] An embodiment of a wheel and hub assembly is schematically illustrated in Figure 1. The wheel and hub assembly comprises a wheel 100 having a hub 1 that has a series of inserts 2 spaced around a surface of the hub 1. The surface of the hub 1 having the inserts 2 faces a brake mechanism (described below) adapted to engage the inserts 2 in order to brake the rotation of the wheel 100. The hub 1 may be formed from a durable material such as, e.g., metal or hard plastic. In some embodiments, the hub 1 is formed via injection-molding. In the depicted embodiment, there are eight inserts 2 substantially evenly spaced around the hub. The inserts 2 have a trapezoidal shape that is raised from the surface of the hub. The number, shape, and/or arrangement of the inserts, 2, can be different in different embodiments. For example, greater or fewer inserts may be used. The inserts 2 can be shaped as protrusions, can be spaced circumferentially around the hub (with substantially equal angular spacing or not), and/or can be shaped as squares, polygons, wedges, rounded protrusions, or other suitable shapes. In some embodiments, the inserts, 2, are not evenly spaced around the hub, 1. In some embodiments, inserts are arranged in more than one circular (or other) pattern. In some embodiments, the inserts 2 can be formed as depressions, holes, or openings in the hub 1. The inserts may be formed from a suitably rigid material such as metal or hard plastic. In some embodiments, the inserts are formed integrally with the hub 1 via injection molding. In other embodiments, the inserts 2 are formed separately and attached to the hub 1. The inserts may be formed on one or both surfaces of the hub, 1.

[0023] In the illustrated embodiment, the wheel and hub assembly also includes an axle, 3, with integrated features 3a for positioning a lock assembly (described below) relative to the inserts in the hub 1. The wheel 100 and the hub 1 rotate around the axle 3. A tread 4 is formed or attached to the hub. Contact between the tread 4 and the surface over which the cart is moving provides frictional resistance to the motion of the cart when the locking mechanism has been activated and rotation of the wheel 100 around the axle 3 is inhibited. The tread 4 may be formed from rubber or polymer via, for example, a molding process. [0024] A brake mechanism 200 is disposed adjacent the wheel 100 (see, e.g., Figs. 8 A and 8B) and configured to engage one or more of the inserts 2 in order to provide a braking force that inhibits rotation of the wheel 100. The wheel 100 and the brake mechanism 200 may be disposed between arms 242 of a caster 240 that can be attached to a leg of the cart. In various embodiments, the brake mechanism 200 can comprise one or more of the following components: a lock assembly to brake (or lock) the wheel, a magnetically-activated trigger mechanism for releasing the lock assembly, a driver mechanism to move the lock assembly from an unlocked to a locked position, and a safety mechanism for preventing unwanted release of the trigger mechanism. Certain non-limiting, illustrative examples of the brake mechanism 200 and its components will now be described with reference to the figures. Example Lock Assembly

[0025] An embodiment of a lock assembly 30 is schematically shown in Figures 2A and 2B. Figure 2A is a view of one side of the lock assembly 30, and Figure 2B is a view of the other side. The lock assembly 30 comprises a lock plate, 5, that is attached to a retainer, 6, and constrained in rotation about the axle, 3, by a positioning plate, 7. The lock plate 5 comprises tabs 25 configured to engage the inserts 2 of the hub 1 when the lock mechanism is in an actuated position. The tabs 25 do not engage the inserts 2 when the lock mechanism is in an unactuated position. In this embodiment, two tabs 25 are shown. In other embodiments, a different number of tabs (e.g., I₅ 3, 4, 5, or more), arrangement and/or shape of tabs, may be used. For example, in some embodiments one tab is used and is configured as an elongated member (e.g., a pin). As will be discussed further below, the tabs 25 engage the inserts 2 on the hub 1 in order to provide a braking force that inhibits rotation of the wheel about the axle 3.

[0026] In the illustrated embodiment, the positioning plate 7 is substantially rectangular in shape and configured to allow movement in one direction (left-right in Fig. 2 A and not up-down in Fig. 2A) in an elongated central opening in the lock plate 5. In this embodiment, the movement direction is perpendicular to the axle 3. The positioning plate 7 has a central opening 7a adapted to engage the features 3 a of the axle 3 in order to restrict rotation of the lock assembly 30 around the axle 3. For example, as shown in Figure 2A, the central opening 7a has fiat sides that engage the flat sides (features 3a) of the axle 3 (see, e.g., Fig. 1), thereby preventing rotation of the positioning plate 7 when the cart is moving and the wheel is rotating. Accordingly, in this example, when the cart is pushed by a user, the wheel rotates but the lock assembly 30 does not rotate.

[0027] The retainer 6 positions the lock plate 5 relative to the axle 3 and relative to the hub inserts 2. The lock assembly 30 is spaced slightly from the wheel and hub assembly so that the hub 1 is able to rotate around the axle 3 (when the wheel is unlocked) while the lock assembly 30 remains rotationally fixed. The retainer 6 operates in conjunction with trigger and reset mechanisms (if provided) as discussed below. For example, teeth 6a of the retainer 6 can be used with the reset mechanism.

[0028] Referring to Figure 2B, the lock assembly can be spring-loaded such that a coil spring, 8, disposed within the retainer 6 provides a spring force in the direction of engagement between the lock plate 5 and the hub inserts 2. The lock plate 5, the retainer 6, and the positioning plate 7 can be formed from one or more rigid materials such as metal or hard plastic. In the illustrated embodiment, the lock plate 5 is attached to the retainer 6 via two screws. In other embodiments, the lock plate 5 can be attached to the retainer 6 with additional or different fasteners, welds, adhesives, etc. Example Trigger Mechanism

[0029] An embodiment of a trigger mechanism 40 is shown in Figures 3 A and 3B. The trigger mechanism 40 can be moved between an unactuated position (shown, e.g., in Figures 3A and 3B) and an actuated position (see, e.g., Fig. 6A) by a magnetic force applied to the trigger mechanism 40. For example, as will be further discussed below, one or more magnets embedded in the pavement over which the wheel rolls can provide the magnetic force to actuate the trigger mechanism 40, which actuates the wheel lock.

[0030] The trigger mechanism 40 comprises a gear and ratchet wheel 9 that engages the lock plate retainer 6. The gear and ratchet wheel 9 are held in position by means of protrusions (not shown) on a structural plate, 10, that is part of the mechanism housing 60 (see, e.g., Figs. 8A and 8B). The gear and ratchet wheel 9 may include an inner gear 9a having teeth that engage the teeth 6a on an edge of the retainer 6. Engagement of the teeth 6a of the retainer 6 and the inner gear 9a of the ratchet wheel 9 are used in embodiments of the reset mechanism (described below).

[0031] A lever, 12, (pivotable around an axis A) is positioned on a structural plate 10 so as to bring a pawl 13 into contact with the ratchet 9. The lever arm 12 is held in this position by a torsion spring, 14, which engages the lever arm 12 at a protrusion 14a. At an end of the lever 12 that is opposite the end with the pawl 13, a magnet retainer 15 is disposed to hold at least one magnet 16. The magnet 16 may comprise a ceramic magnet, a neodymium magnet, an alnico magnet, a ferrornagnet, or any other type of magnet. In some embodiments, an electromagnet may be used (e.g., powered by a battery, ultracapacitor, wheel power generator, etc.). In the illustrated embodiment, the structural plate 10 comprises a depression 10a that permits the magnet 16 and the magnet retainer 15 to move (as the lever 12 pivots) without contacting the structural plate 10. In other embodiments, the magnet 16 and the magnet retainer 15 may be shaped and/or sized differently so that the depression 10a is not needed. In various embodiments, the distance from the lever arm pivot point, A, to the magnet 16, the size and/or orientation of the magnet 16, may be different depending on the strength of the magnetic force required to actuate the trigger mechanism. The strength of the magnetic force required to actuate the trigger mechanism 40 may be selected to be above a threshold so that small, stray magnetic fields and/or electromagnetic interference do not actuate the trigger.

[0032] In various embodiments, the location and position of the trigger mechanism 40 relative to the wheel and lock assembly 30 may vary depending on the strength of the magnetic force required to actuate the lock mechanism as well as the proximity and/or strength of the source of a triggering magnetic field. Many variations are possible.

[0033] In the illustrated embodiment, the gear and ratchet 9 comprise a hexagonal shaped protrusion, 11, (see, e.g., Fig. 3B) that, when turned with a key having corresponding hexagonal mating features (see, e.g., Figs. 5A and 5B), resets the position of the trigger mechanism after it has been actuated. In some embodiments, the size of the protrusion is a standard hexagonal bolt gauge. Accordingly, the trigger mechanism 40 may be reset from the actuated position to the unactuated position, which unlocks the wheel and allows the cart to be rolled. Example Safety Mechanism

[0034] An embodiment of a safety mechanism 50 is schematically shown in Figure 4. The safety mechanism 50 comprises a retainer, 17, positioned on the structural plate, 10 (not shown in Fig. 4), in such a way as to bring a portion 17a of the retainer 17 into contact with a portion 13a of the top surface of the lever pawl, 13, when no triggering magnetic field is present. In the depicted embodiment, the retainer 17 is an elongated member configured to pivot around axis B and to allow the portion 13a to move into and out of contact with the top portion 13a of the pawl 13. The retainer 17 inhibits the lever pawl 13 from escaping from the gap between teeth in the gear and ratchet 9. Contact between the portions 13a and 17a advantageously tends to keep the pawl 13 in contact with the gear and ratchet 9, which can inhibit or prevent inadvertent or unwanted triggering of the lock mechanism by non-magnetic forces caused by, e.g., jarring, rough handling, or collisions of the cart.

[0035] The retainer 17 is configured to hold a retainment magnet, 18. The safety mechanism 50 may be actuated using a magnetic key (see, e.g., Fig. 5A) that applies a magnetic force to the retainment magnet 18 and will be described below for the reset mechanism. The safety mechanism 50 is optional and is not included in some embodiments of the wheel lock mechanism. Example Reset Mechanism

[0036] An embodiment of a reset mechanism is schematically shown in Figures 5A and 5B. In this embodiment, the reset mechanism includes a reset key, 19, comprising a reset magnet, 20, and a hexagonal socket, 21, configured to mate with the protrusion, 11, on the gear and ratchet wheel 9. The key 19 includes a handle 19a that allows a user to turn the key. The key 19 may be formed from a durable material such as metal or hard plastic. In some embodiments, the key 19 is injection molded. The reset magnet 20 may be molded-into the key 19. In other embodiments, the socket 21 and the protrusion 11 may have shapes different from hexagonal.

[0037] The key 19 comprises features 22 and 22a. The feature 22 on the key 19 is configured in shape and size to fit in a slot 23 in the housing 60 for the lock mechanism so that the socket 21 can engage the protrusion 11. In the illustrated embodiment, the slot 23 includes two U-shaped openings 23a, 23b. The feature 22a comprises a protrusion that is configured to fit through the openings 23 a, 23b of the slot 23. The feature 22a and the openings 23a, 23b advantageously allow the key 19 to be inserted into the slot 23 in only a range of angular orientations, which allows the reset magnet 20 to apply a magnetic force to the retainment magnet 18 of the safety retainer 17. For example, the key 19 is inserted so that the feature 22 fits in the slot 23 with the feature 22a passing through the opening 23 a. The structural plate 10 is spaced sufficiently from the inner surface of the housing 60 so that the key 19 can be rotated clockwise to reset the lock assembly. The key 19 can be removed when the feature 22a is aligned with the opening 23b. Use of the two openings 23a, 23b is advantageous in this embodiment, because it ensures the key 19 is inserted in the proper orientation so that the magnet 20 can repel the retainraent magnet 18 and so that the lock assembly is completely reset to the unactuated position. In other embodiments, the openings 23a, 23b are not used or may be configured differently than shown. For example, in some embodiments, a single, angularly elongated opening is used which has an angular extent comparable to the angular extent between the openings 23a, 23b shown in Figure 5B. Accordingly, in the illustrated embodiment, the slot 23 (and the openings 23a, 23b) are arranged so that when the key 19 is inserted into the slot 23, the reset magnet 20 is positioned in a specific orientation relative to the retainment magnet, 18, of the safety retainer, 17. In some embodiments, the reset magnet 20 in the key 19 and the retainment magnet 18 in the safety retainer 17 are configured to repel (rather than attract) each other. The orientation provides that, due to the repellant magnetic force between the reset magnet 20 in the key 19 and the retainment magnet 18 in the safety retainer 17, the retainer 17 will be in the correct position relative to the pawl, 13, in order to reset the trigger mechanism.

[0038] Figure 6 A below schematically shows embodiments of the trigger mechanism 40 and the lock mechanism in an actuated position. After the reset key 19 is inserted into the slot 23 and rotated clockwise (as viewed from outside the wheel housing 60), the lock plate 5 is returned to the reset position (e.g., unactuated position) as shown in Figure 6B, in which the wheel can freely rotate (as described below). Rotation of the reset key 19 causes the ratchet wheel 9 to rotate, which in turn causes the inner gear 9a to rotate. Because teeth of the inner gear 9a engage teeth 6a on the edge of the retainer 6, the retainer 6 is moved laterally to the right (in the views shown in Figures 6A and 6B) so that the tabs 25 move radially inward toward the axle 3 and out of engagement with the inserts 2. Accordingly, the lock mechanism is reset to the unactuated state. Example Wheel and Wheel Assembly

[0039] Figure 7 is an exploded view that schematically shows an embodiment of a wheel assembly 210 comprising a wheel 212 and a caster 240 (also known as a "fork" or a "yoke"). The wheel assembly 210 is adapted to be attached to a non-motorized vehicle, such as a cart, by being screwed in to the vehicle's frame. The wheel assembly 210 can be used to replace one (or more) of the wheels on the vehicle. For example, the wheel assembly 210 can replace a standard-sized front (and/or rear) wheel on a shopping cart. In certain embodiments, the wheel 212 has a diameter of about five inches, although the wheel 212 can be larger or smaller in other embodiments. The wheel 212 includes a tire 213 (or molded tread 4 shown in Fig. 1) that is circumferentially disposed about a hub 218. The wheel 212 may be generally similar to embodiments of the wheel 100 described herein. The hub 218 may be generally similar to embodiments of the wheel hub 1 described herein. For example, in some embodiments, one of the surfaces of the hub 218 includes the inserts 2. The hub 218 rotates with the tire 213.

[0040] In the embodiment shown in Figure 7, the wheel 212 is disposed between end portions (or arms) 242 of the caster 240. The end portions 242 fit into "U"- shaped retaining clips 225. A bolt 228 passes through the retaining clips 225, the end portions 242, and a hollow axle 234 in the center of the hub 218. A nut 232 is tightened to secure the wheel 212 to the caster 240. The axle 234 has flat portions 235 that engage shaped holes 237 in the retaining clips 225. The axle 234 is prevented from rotating by the interference fit between the "U"-shaped sides of the retaining clips 225 and the end portions 242 of the caster 240. The axle 234 and the flat portions 235 shown in Figure 7 can correspond to the axle 3 and the integrated features 3 a shown in Figure 1.

[0041] The hub 218 may, but need not, have a cover 221 that protects components (if any) disposed within the hub 218 from environmental conditions In addition, the cover 221 prevents internal components from being seen and tampered with by users of the vehicle. The hub 218 (and the cover 221) can be fabricated from rigid, lightweight materials including plastics such as nylon or acrylonitrile butadiene styrene (ABS). Internal components (if any) disposed within the hub 218 can be prevented from rotating by attaching them to the non-rotating axle 234. The wheel 212 can be configured to contain some or all portions of other suitable systems including, for example, electronic components for a cart confinement system, an electronic communication system (for wirelessly communicating to electronic components outside the wheel 212), a power system to supply electrical power to electronic components, and so forth. Examples of some of these components (including but not limited to a wheel power generator) are described in U.S. Patent Publication No. 2006/0249320, published November 9, 2006, entitled "Power Generation Systems and Methods for Wheeled Objects," which is hereby expressly incorporated by reference herein in its entirety. Example Operation of an Embodiment of a Wheel Lock Mechanism

[0042] In some implementations suitable for a cart containment system, the wheel and caster assembly (see, e.g., Fig. 7) can be installed on one (or more) of the legs on a cart or other wheeled vehicle (e.g., a shopping cart). Figure 8A schematically illustrates an embodiment of a wheel and wheel lock mechanism (inside a housing 60) that can move over a surface (not shown) having an embedded magnet 24. The wheel lock mechanism is unactuated in Figure 8 A. Figure 8B schematically illustrates the wheel and wheel lock mechanism of Figure 8 A as they pass over the embedded magnet 24. The embedded magnet 24 provides a triggering magnetic field that is sufficiently large to actuate the wheel lock when the cart is sufficiently close to the position of the magnet 24. The housing 60 shown in Figure 8A has been removed in Figure 8B to illustrate the wheel lock mechanism in the actuated position.

[0043] With reference to Figure 8A, the wheel lock mechanism can be disposed in the housing 60, which is disposed between the wheel 212 and an arm of the yoke 240. The housing 60 does not rotate when the wheel 212 rotates due to engagement between the features 3a of the axle 3 and the opening 7a of the positioning plate 7 of the lock assembly 30 (see, e.g., Fig. 1). The wheel turns freely with the lock mechanism in the reset position (unactuated position) shown, for example, in Figure 6B. As the wheel passes over the magnet, 24, disposed in, on, or under the pavement (not shown) or surface (not shown) upon which the cart travels, the magnetic field of the magnet 24 exerts magnetic forces on the trigger mechanism 40 (e.g., including the magnet 16) of the wheel lock mechanism. The magnet 24 may comprise one or more magnets, which may be any suitable type of magnet such as, e.g., a permanent magnet, an electromagnet, and so forth. The magnet 24 may be embedded slightly below the surface of the pavement to reduce wear on the magnet 24. The magnet 24 may comprise one or more strips of magnetic material that are disposed in, on, or under the surface. For example, a magnetic strip may be disposed underneath flooring in a retail store.

[0044] In some embodiments, the magnet 24 is oriented to repel the retainment magnet 18 in the safety retainer 17 and to attract the magnet 16 on the lever 12. With reference to Figures 6A and 6B, in some such embodiments, the safety retainer 17 pivots counterclockwise, because the magnet 24 repels the retainment magnet 18. The lever 12 pivots also pivots counterclockwise as the magnet 16, because the magnet 16 is attracted to the magnet 24. The pivoting of the safety retainer 17 allows the pawl 13 to disengage from the ratchet 9, which allows the coil spring 8 to decompress and force the retainer 6 perpendicularly away from the axle 3. Movement of the retainer 6 away from the axle 3 causes the tabs 25 to engage the inserts 2 on the wheel hub 1, which brakes or locks the wheel. Other magnetic orientations are possible. [0045] In some embodiments, the strength of the magnetic force required to actuate the trigger mechanism 40 is selected to be above a threshold so that small, stray magnetic fields and/or electromagnetic interference do not actuate the trigger mechanism 40. Accordingly, the strength of the magnet 24 may be selected so that the triggering magnetic field is above the threshold and can actuate the lock mechanism from the unactuated (e.g., unlocked) position to the actuated (e.g., locked) position as the cart passes over or nearby the magnet 24. The strength of the magnet 24 may depend, at least in part, on factors including the position of the magnet (e.g., whether located under flooring or under pavement), the presence and magnitude of other external or stray magnetic or electromagnetic fields, the strength of the magnet 16 in the trigger mechanism 40, the strength of the retainment magnet 18 in the safety mechanism 50, and so forth.

[0046] hi one illustrative example of operation schematically shown in Figure 9, as the wheel assembly passes over the magnet 24 in the pavement (not shown in Fig. 9), the magnet, 18, held by the safety retainer, 17, moves into the position shown in Figure 9. In this embodiment, the magnet 18 is oriented in such a way as to be repelled by the magnetic field of the magnet 24 in the pavement. In reaction to this magnetic force, the safety retainer 17 rotates in a counterclockwise direction (as seen in Figure 9) around pivot point B, removing contact between the portion 17a of the retainer 17 and the portion 13a of the pawl 13, which allows the pawl 13 to rotate counterclockwise about the axis A. At about the same time, the magnet 16 at the end of the lever arm, 12, is attracted to the magnet, 24, in the pavement. This attractive magnetic force causes the lever 12 to rotate counterclockwise around axis A into the position shown in Figure 9. (See also, e.g., Figs. 6 A and 6B).

[0047] As the pawl 13 rotates out of contact with the gear and ratchet wheel, 9, the latch plate retainer 6 is free to slide laterally relative to the positioning plate 7 (see, e.g., Fig. 2A). The coil spring 8, which is compressed between the feature 3a of the axle 3 and the lock plate retainer 6, urges the lock plate retainer 6 laterally to the left (as shown in Fig. 9), and the tabs 25 move radially outward from the axle 3 toward engagement with the inserts 2 on the hub 1. As the lock plate retainer 6 moves toward the actuated position, end portions of the two tabs 25 (see, e.g., Fig. 10 and Figs. 2A and 3A) on the lock plate, 5, move into spaces between adjacent inserts 2 on the hub 1. For example, with reference to Figure 10, tab 25a moves between adjacent inserts 2a and 2b, and tab 25b moves between adjacent inserts 25b and 25c. It is advantageous if the end portions of the tabs 25 move sufficiently into the space between adjacent inserts 2 that the wheel is substantially locked against further rotation (apart from the "play" described below). Accordingly, in the actuated position, the tab 25a engages the inserts 2a, 2b, and the tab 25b engages the inserts 2b, 2c so as to provide brake or lock the wheel. As used herein, in the actuated position, the tab 25a engages the inserts 2a, 2b (and the tab 25b engages the inserts 2b, 2c) even though the tab 25a (or the tab 25b) does not physically contact the inserts 2a, 2b (or the inserts 2b, 2c) at all times (e.g., there may be a degree of "play" as described below). For any degree of "play" in an embodiment, a relatively small amount of rotation of the wheel will cause physical between the tabs and the adjacent inserts sufficient to brake or lock the wheel. For example, in the embodiment shown in Figure 10, the tabs 25 a, 25b engage the inserts 2a, 2b and 2b, 2c, respectively, when at least the end portions of the tabs 25a, 25b are disposed in the spaces between adjacent inserts 2a, 2b and 2b, 2c, respectively. If the wheel 100 shown in Figure 10 were to rotate slightly in the clockwise direction, the insert 2b would physically contact the tab 25 a, and the insert 2c would physically contact the tab 25b, and such physical contact would substantially inhibit further rotation of the wheel 100. Rotation of the wheel 100 would also be substantially inhibited if the wheel were to rotate in the counterclockwise direction, because the insert 2a would physically contact the tab 25a, and the insert 2b would physically contact the tab 25b.

[0048] In the actuated position, the embodiment of the wheel 100 shown in Figure 10 is substantially "locked" and inhibited from rotating about the axle 3, because further rotation causes one of the adjacent inserts to physically contact the tab. The size and/or shape of the tabs 25 and/or inserts 2 may be selected (among other factors) so that the physical contact provides a braking force on the wheel rotation, which may be sufficiently large to lock the wheel in some implementations. Depending (at least in part) on the size of the tabs 25 compared to the spacing between adjacent inserts 2, the wheel 100 may have various degrees of rotational "play" when the lock mechanism is actuated and the tabs 25 engage the inserts 2. For example, if the tabs 25 are relatively small compared to the insert spacing, the wheel may be able to rotate back and forth (slightly) as the tabs 25 move between contacting a first insert and then a second adjacent insert. If the tabs 25 are just slightly smaller than the spacing between adjacent inserts, the wheel may have relatively little rotational "play" when the lock mechanism is actuated. [0049] Although two tabs 25 are shown in the illustrated embodiments, a different number of tabs (e.g., 1, 3, 4, 5, or more) may be used in other embodiments. Also, the tabs 25 may be configured differently than shown. For example, the inserts 2 may comprise inclined surfaces, and the tabs 25 may engage the inclined surfaces to provide a frictional braking force that inhibits rotation of the wheel about the axle 3. In various embodiments, the amount of the braking force may vary (e.g., from a relatively small braking force to an amount sufficient to substantially lock the wheel).

[0050] Resetting the wheel lock mechanism from the actuated position to the unactuated position can be accomplished by inserting the key, 19, into the slot, 23, in the housing 60 and rotating the gear and ratchet wheel 9 clockwise. (See the Example Reset Mechanism section above). To prevent unauthorized reset, the space between edges of the slot 23 and the protrusion 11 may be sufficiently small that it is difficult to insert something other than the authorized key 19 (e.g., a wrench or ratchet) into the slot 23. In some embodiments, the protrusion 11 may have a shape that is not a conventional or common bolt shape (e.g., the protrusion 11 may be non-hexagonal), which also reduces the likelihood of unauthorized reset via conventional or commonly available tools. Additional illustrative examples and embodiments

[0051] In some embodiments, a magnetically actuated wheel lock mechanism usable with a wheel for a non-motorized cart comprises a spring- loaded lock mechanism capable of causing first features of the lock mechanism to engage second features on the exterior of a wheel (e.g., in or on a wheel hub), thereby causing the wheel to become substantially fixed in rotational position and substantially unable to rotate. In some embodiments, the first features comprise tabs and the second features comprise raised protrusions. In other embodiments, the first features comprise tabs, the second features comprise depressions, the tabs engaging the depressions to cause the wheel rotation to be inhibited.

[0052] hi some embodiments, a wheel lock mechanism for a wheel comprises a wheel assembly, with a series of protrusions or other geometrical features arranged in a circumferential pattern on an exterior surface of the wheel. The wheel comprises an axle, and one or more features for positioning a lock assembly relative to the surface of the wheel. The wheel lock mechanism may further include a trigger mechanism for restricting movement of the lock assembly relative to the exterior of the wheel. The trigger mechanism may be released by the attraction of a magnet in the lock mechanism to a magnet placed on or embedded in the surface on which the wheel is in contact. The wheel lock mechanism may also include a safety mechanism configured to prevent (or reduce the likelihood of) the inadvertent release of the lock mechanism due to nonmagnetic forces. Embodiments of the wheel lock mechanism may include a reset mechanism for resetting the wheel lock mechanism after it has been actuated.

[0053] An embodiment of a braking mechanism for a wheel is provided. The braking mechanism comprises a wheel assembly that includes a plurality of protrusions or other geometric features arranged in a circumferential pattern and integrated into a plastic material from which a wheel hub is injection molded. The braking mechanism may include a lock assembly that includes integral tabs arranged to correspond with radial gaps between the protrusions (or features) in the wheel hub. The tabs can be configured to be capable of sliding laterally and prevented from rotating in relation to a wheel axle, in reaction to the force resulting from a coil spring.

[0054] In another embodiment, the lock assembly may include a pin capable of being laterally released or inserted into a position in which interference is created between the pin and the corresponding radial features on the wheel hub, thereby inhibiting the rotation of the wheel.

[0055] In some embodiments, the braking mechanism comprises a gear and pawl component capable, when rotated, of actuating the lock assembly in a lateral direction by means of a rack and pinion gear tooth arrangement. Embodiments of the braking mechanism may include a trigger mechanism capable of retaining, as the result of the reaction force to a torsion spring, and releasing the gear and pawl component, as a result of the reaction to the repellant force between a magnet, incorporated into a lever arm and a magnet embedded in or on a pavement surface.

[0056] Embodiments of the braking mechanism may include a reset mechanism comprising a key used to reset the braking mechanism to its unlocked position. The key may have, incorporated into its structure, a small magnet for repelling a separate magnet attached to a pendulum comprising a safety retainer.

[0057] In some embodiments, the braking mechanism is disposed in a housing allowing for the insertion of the reset key in only one specific position relative to the trigger mechanism and safety retainer.

[0058] In some embodiments, the braking mechanism may be configured such that the wheel hub, locking assembly, and housing are attached to a cart frame using a caster assembly. In some such embodiments, the caster assembly is capable of rotating in a circle so that the wheel and locking mechanism are positioned on the same side of the cart relative to the direction of travel.

[0059] In some embodiments, a magnet is embedded in, on, or under (or otherwise affixed to) the pavement, and whose magnetic field is used for the activation of the wheel lock mechanism. In some implementations, the magnet comprises one or more permanent magnets and/or one or more electromagnets. One possible advantage of electromagnets is that, if desired, the containment system may be at least partially deactuated by turning off power to some or all of the electromagnets. One possible advantage of permanent magnets is that the magnets can be located in positions where it is difficult or undesirable to provide a power cable (e.g., for an electromagnet). Another possible advantage of permanent magnets is that strips of magnetic material are commercially available and can be readily attached to a surface (e.g., some magnetic strips have an adhesive backing that permits easy installation).

[0060] In certain embodiments, the magnetic polarities of the various magnets may be reversed as compared to the description herein. For example, as is well know, to achieve a repelling magnetic force, one or more pairs of North magnetic poles may be used, or one or more pairs of South magnetic poles may be used. As is also well known, an attractive magnetic force is provided between a North magnetic pole and a South magnetic pole. Thus, for example, to achieve an attractive force between a magnet in the wheel and a magnet in the pavement, a North pole may be used in the wheel, and a South pole may be used in the pavement or a South pole may be used in the wheel, and a North pole may be used in the pavement. Many variations in the magnetic geometry may be used.

[0061] In some embodiments of a cart containment system for use with non- motorized, wheeled carts, the cart containment system comprises a non-motorized cart having at least one wheel assembly that comprises a wheel and a brake mechanism. The brake mechanism is actuatable to brake rotation of the wheel in response to a triggering magnetic field. The brake mechanism may be configured to be actuatable only if the triggering magnetic field is above a threshold. A magnet is configured to provide the triggering magnetic field. The magnet can be disposed in, on, or under a surface over which the cart can travel. The magnet may be a permanent magnet, an electromagnet, or a combination thereof. In some implementations, the cart comprises a first wheel assembly in which a first brake mechanism is actuatable in response to a triggering magnetic field above a first threshold and a second wheel assembly in which a second brake mechanism is actuatable in response to a triggering magnetic field above a second threshold that is different from the first threshold.

[0062] Some such implementations advantageously may be used to contain carts into different containment areas of a facility. For example, the second threshold may be lower than the first threshold. A cart having both the first and the second wheel assemblies will be braked if the cart passes over a magnet with a strength exceeding either the first threshold or the second threshold. However, a cart having only the first wheel assembly (and not the second wheel assembly) will be braked only by the magnets providing a triggering magnetic filed above the first (higher, in this example) threshold but will not be braked when passing over magnets providing the second (lower, in this example) threshold. Accordingly, different carts can be contained in different regions of the facility. Other implementations are possible.

[0063] Although described in the illustrative context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the disclosure extends beyond the specifically described embodiments to other alternative embodiments and/or uses and obvious modifications and equivalents. Similarly, it should be appreciated that in the above description of embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that any disclosed embodiment require more features than are expressly described. Rather, inventive aspects lie in a combination of fewer than all features of any single foregoing disclosed embodiment.

[0064] Also, in any method or process disclosed herein, the acts or operations of the method or process may be performed in any suitable sequence and are not necessarily limited to any particular disclosed sequence. Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding certain embodiments; however, the order of description should not be construed to imply that these operations are order dependent. Additionally, the structures, systems, and/or devices described herein may be embodied as integrated components or as separate components. Components may be combined, rearranged, or not used in various embodiments. Further, the example embodiments described herein have several features, no single one of which is indispensable or solely responsible for their desirable attributes.

[0065] For purposes of comparing various embodiments, certain aspects and advantages of these embodiments are described. Not necessarily all such aspects or advantages are achieved by any particular embodiment. Thus, for example, various embodiments may be carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other aspects or advantages as may also be taught or suggested herein.

[0066] Reference throughout this application to "some embodiments" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least some embodiments. Thus, appearances of the phrases "in some embodiments" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment and may refer to one or more of the same or different embodiments. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments. Also, as used in this application, the terms "comprising," "including," "having," and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term "or" is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term "or" means one, some, or all of the elements in the list.

Claims

WHAT IS CLAIMED IS:

1. A wheel and brake mechanism for use with a non-motorized cart, the wheel and brake mechanism comprising: a wheel rotatable about an axle, the wheel comprising a hub having a plurality of first engagement features; and a brake mechanism configured not to rotate when the wheel rotates, the brake mechanism comprising: at least one second engagement feature that is movable between an unactuated position and an actuated position; and a trigger configured to maintain the second engagement feature in the unactuated position, and in response to a triggering magnetic field, to allow the second engagement feature to move from the unactuated position to the actuated position, wherein in the unactuated position the second engagement feature does not engage any of the plurality of first engagement features and in the actuated position the second engagement feature operatively engages at least one of the first engagement features so as to provide a braking force that inhibits rotation of the wheel about the axle.

2. The wheel and brake mechanism of Claim 1, wherein the wheel and brake mechanism is configured for use with a shopping cart.

3. The wheel and brake mechanism of Claim I₅ wherein the plurality of first engagement features comprise protrusions.

4. The wheel and brake mechanism of Claim 3, wherein the protrusions are circumferentially spaced around the hub.

5. The wheel and brake mechanism of Claim 3, wherein the second engagement feature is configured such that when in the actuated position an end portion of the second engagement member is disposed between adjacent protrusions.

6. The wheel and brake mechanism of Claim 1 , wherein the brake mechanism comprises a spring configured to urge the second engagement feature from the unactuated position toward the actuated position.

7. The wheel and brake mechanism of Claim 1 , wherein the trigger comprises a ratchet mechanically coupled to the second engagement feature and a pawl having a first end configured to engage the ratchet so as to maintain the second engagement feature in the unactuated position and a second end comprising a magnet responsive to the triggering magnetic field.

8. The wheel and brake mechanism of Claim 7, wherein in response to the triggering magnetic field, the pawl is configure to pivot sufficiently for the first end to disengage from the ratchet, thereby allowing the second engagement feature to move to the actuated position.

9. The wheel and brake mechanism of Claim 7, further comprising a retainer configured to move from a first position to a second position in response to the triggering magnetic field, such that when in the first position the retainer is configured to inhibit disengagement of the first end of the pawl from the ratchet when the second engagement feature is in the unactuated position, and such that when in the second position the retainer is configured not to inhibit disengagement of the first end of the pawl from the ratchet.

10. The wheel and brake mechanism of Claim 9, wherein the retainer comprises a pivotable elongated member having a retainment magnet, the elongated member configured to pivot from the first position to the second position in response to the triggering magnetic field.

11. The wheel and brake mechanism of Claim 10, wherein polarity of the retainment magnet is opposite to polarity of the magnet at the second end of the pawl.

12. The wheel and brake mechanism of Claim 7, further comprising a reset key configured to rotationally engage the ratchet so as to move the second engagement feature from the actuated position to the unactuated position.

13. The wheel and brake mechanism of Claim 1, further comprising a caster configured to support the axle, the caster having an end configured to be attached to the cart.

14. A wheel assembly for use with a human-propelled cart, the wheel assembly comprising: a caster having an end configured to be attached to the human-propelled cart, the caster configured to support an axle; a wheel rotatable about the axle, the wheel comprising a hub having a plurality of engagement features; a lock assembly mountable on the axle adjacent the wheel, the lock assembly configured not to rotate about the axle, the lock assembly comprising: a lock plate configured to move in a direction perpendicular to the axle between an unlocked position and a locked position, the lock plate comprising a lock member configured to engage at least one of the plurality of engagement features of the hub when the lock plate is in the locked position; a trigger configured to maintain the lock plate in the unlocked position, the trigger actuatable to release the lock plate in response to a triggering magnetic field; and a spring-loaded driver configured to move the lock plate between the unlocked position and the locked position when the lock plate is released by the trigger.

15. The wheel assembly of Claim 14, wherein the caster comprises a pair of opposed arms configured to support the axle therebetween, the wheel and the lock assembly mountable between the opposed arms.

16. The wheel assembly of Claim 14, wherein the plurality of engagement features comprises a plurality of protrusions spaced circumferentially around the hub.

17. The wheel assembly of Claim 14, wherein, when in the locked position, the lock member is disposed between two adjacent engagement features.

18. The wheel assembly of Claim 14, wherein the trigger comprises a ratchet in operative engagement with the lock plate and a pawl configured to engage the ratchet so that the lock plate is held in the unlocked position and to disengage from the ratchet so that the lock plate is allowed to move to the locked position.

19. The wheel assembly of Claim 18, further comprising a retention mechanism configured to inhibit disengagement of the pawl from the ratchet when the lock plate is in the unlocked position, the retention mechanism actuatable in response to the triggering magnetic field to allow disengagement of the pawl from the ratchet so that the lock plate can move to the locked position.

20. The wheel assembly of Claim 14, wherein the spring loaded driver comprises a coil spring having a first end disposed against the axle and a second end that engages the lock plate, the coil spring substantially compressed when the lock plate is in the unlocked position.

21. The wheel assembly of Claim 14, further comprising a manually-activated reset mechanism operable to move the lock plate from the locked position to the unlocked position.

22. The wheel assembly of Claim 20, wherein the lock assembly comprises a rotatable gear that engages the lock plate, the lock plate movable from the locked position to the unlocked position in response to rotation of the gear.

23. The wheel assembly of Claim 22, further comprising a reset key configured to rotate the gear.

24. A cart containment system for use with non-motorized, wheeled carts, the cart containment system comprising: a non-motorized cart having at least one wheel assembly comprising a wheel and a brake mechanism, the brake mechanism actuatable to brake rotation of the wheel in response to a triggering magnetic field; and a permanent magnet configured to provide the triggering magnetic field, the permanent magnet disposed in, on, or under a surface over which the cart can travel, wherein the brake mechanism comprises a brake member that can move between a first position in which the brake member does not contact an engagement surface of the wheel to a second position in which the brake member contacts the engagement surface of the wheel to cause a braking force to be applied to the wheel, the brake mechanism configured to move the brake member from the first position to the second position when the wheel assembly of the cart passes over the permanent magnet.

25. The cart containment system of Claim 24, wherein the non-motorized cart is a shopping cart provided by a retail store.

26. The cart containment system of Claim 25, wherein the permanent magnet is disposed at an exit to the retail store.

27. The cart containment system of Claim 24, wherein the permanent magnet comprises a strip of magnetic material.

28. The cart containment system of Claim 24, wherein the braking force is sufficiently large to lock the wheel against rotation.

29. The cart containment system of Claim 24, wherein the engagement surface of the wheel comprises a plurality of raised engagement features and wherein when the brake member is in the second position, an end portion of the brake member is disposed between adjacent raised engagement features.

30. The cart containment system of Claim 24, wherein the brake mechanism comprises a manual reset mechanism operable to move the brake member from the second position to the first position, thereby unbraking the wheel.