Field of the invention

[0001] The present invention relates to shoe and, in particular, to work shoes destined to be used on magnetizable surfaces such as iron or steel, and a removable sole protector.

Background of the invention

[0002] Footwear is an important part of a worker’s equipment. Not only does it provide protection to the feet with features such as steel cap front or waterproofness but also enhance worker agility by providing him with better grip and stability.

[0003] Tn the building industry, many workers climb on roofs, scaffolding or similar metal, including magnetic metal, structures that provide little grip and can be slippery. Even on flat steel surfaces substantial dexterity is required not to fall. On uneven surfaces, such as corrugated steel sheets, the contact area with the footwear is significantly reduced as is the grip

[0004] US Patent 8,371,046 describes a riding boot for use with a stirrup. US Patent Publication 2003/0075890 Al describes a magnetic skateboard attachment system. US Patent 10,897,948 B2 describes footwear roofing shoes having a plurality of spaced apart magnets located adjacent the outsole to provide a gripping force to a ferrous metallic surface.

[0005] A need remains for magnetic footwear that provides excellent grip and stability on metal, particularly magnetic metal, surfaces with a durability equivalent or higher than state of the art work shoe soles.

Summary of the invention

[0006] The present invention provides a sole to be used in combination with a footwear, referred to hereinafter as a shoe or shoes in order to provide grip the sole with magnetic attraction and on magnetic metal surfaces, and specifically on ferromagnetic metallic surfaces, for example, metal roofs.

[0007] The present invention provides a magnetic sole for a shoe, and a magnetic shoe thereof. The magnetic sole comprises one or more magnets embedded within a resilient material that forms the sole body. [0008] In a first embodiment, the sole comprises a resilient material comprising at least one first magnet and one or more first paramagnet disposed above the at least one first magnet. The at least one first magnet and the one or more paramagnet are embedded in the resilient material without air space between them and the resilient material. Preferably the resilient material is bonded directly to the outside surface of the body of the magnet(s)

[0009] In various embodiments, the paramagnet is maintained within the resilient material by mechanical embedding. The lateral outer periphery of the paramagnet exceeds the periphery of the magnet in order to create a shoulder within the resilient materia! that serves as an vertical support that inhibits or prevents vertical movement of the paramagnet toward the bottom surface of the sole. The magnet, which is magnetically attracted to the paramagnet, is thus maintained within the resilient material by the force of magnetic attraction exerted by the magnet onto the supported paramagnet

[0010] In various embodiments, the sole comprises a plurality of magnets and associated paramagnets for anchoring of the magnets within the resilient material and reinforcing the magnetic attraction of the ferromagnetic metal surface by the magnets by concentrating the magnetic flux that the magnets generate towards the ferromagnetic metal surface

[0011] In various embodiments, the paramagnets are arranged in multiple sheets of less than 5 mm of thickness and even preferably less than 2 mm of thickness.

[0012] In various embodiments, the combinations of paramagnets and magnets are arranged to not interfere with the natural flexion of the foot during walking. To this end, the combinations located under the front of the foot are oriented in a direction transverse to the length of the foot, and are less than 60 mm wide and preferably less than 30 mm wide in order to allow this flexion.

[0013] In various embodiments, a layer of fiberous fabric that is more resistant to traction than the resilient material is present within the resilient material beneath either or both the paramagnets and the magnets, to limit, reduce or eliminate the propagation of cracks or tears wi thin the resilient material. The layer of fiberous fabric can include one or more non-woven or woven fabrics, comprising fibers and threads made of a material that can include, but is not limited to, nylon, aramid, polyester, polypropylene, carbon fiber, and a combination thereof. [0014] In various embodiments, the resilient material is polymeric, and can include one or more of a thermoplastic and a thermoset

[0015] In various embodiments, the sole inferior surface is flat or planar, to maximize the contact area between the sole and a flat surface onto which the shoe stands. In various embodiments, the sole bottom comprises a rubber with a durometer between 35 Shore A and 75 Shore A.

[0016] In various embodiments, the sole is part of a shoe which also contains a vamp that ensures user comfort and foot support. The vamp includes a bottom plate or panel sometimes referred to as midsole or insole, to close off the botom.

[0017] In various embodiments, the shoe comprises a shock absorber below the heel, preferably made of an expanded polymeric material.

[0018] In various embodiments, the resilient material is polymeric and is polymerized after contact with the vamp of the shoe, the magnets, the paramagnets, the traction resistant fibers and the shock absorber. This allows assembly without a separate glue or adhesive.

[0019] There is also disclosed a removable protective device adapted to attach to the sole of the shoe that protects the sole when the user is not moving on a surface requiring magnetic grip.

[0020] Tn various embodiments, the removable protective device comprises a flexible sole, on or more paramagnets, and at least one protrusion along the periphery of the latter. The removable protective device can further include a release means, such as a tongue also at the periphery of the flexible sole The paramagnets allow the removable protective device to attach to the sole of the magnetic shoe by magnetic attraction and limit the propagation of the magnetic field of the sole’s magnets towards the ground, which also reduces the attraction of magnetic metal objects present on the ground such as nails or staples to the bottom surface of the removable protective device.

[0021] In various embodiments, the paramagnets of the removable protective device are positioned parallel and facing, in registry with, the magnet or magnets embedded within the sole of the magnetic shoe.

[0022] In various embodiments, one of protrusions is positioned at the back of the heel so as to provide mechanical support against which the user can place his heel when ataching the removable protective device with the sole of the shoe. This decreases the degree of precision required for placing the shoes into the correct position for atachment onto the removable protective device.

[0023] The user/shoe wearer preferably holds or pins the tongue of the removable device against the ground with one of his feet to disengage the removable protective device from the sole of the other foot.

[0024] There is further disclosed a resilient material having embedded therein solid magnets, formed by molding a curable or hardenable liquid material over the magnets, and then curing or hardening the liquid material into a solid state and forming the resilient material, whereby the resilient material is bond to the solid magnets when the solidification process is complete.

[0025] In various embodiments, the resilient material contains a rubber, the rubber selected from the group consisting of polyurethane rubber, styrene butadiene rubber, natural rubber, ethylene propylene diene terpolymer rubber, ethylene-vinyl acetate rubber, nitrile butadiene rubber, neoprene® rubber, silicone rubber, and isoprene rubber.

[0026] In various embodiments, the magnets are coated with an epoxy or other bonding material that provides a strong bond with a rubber material, for example, a polyurethane-based material .

[0027] In the present invention, the grip and stability are achieved by the combination of magnets and a flexible polymeric contact surface with the ferromagnetic metal surface. In order to get a strong magnetic traction between the magnets and the bottom surface of the outer sole (and thus, the ferromagnetic metal surface), the material thickness from the bottom surface of the magnet to the bottom surface of the outer sole is up to about 10 millimeters.

[0028] The magnets provide magnetic traction for the shoes toward the ferromagnetic metal surface upon which they are placed. While this magnetic pulling force helps provide better grip and stability, it also creates strain below each magnet into the resilient material. Since the layer of resilient material beneath each magnet is sufficiently thin to allow for a strong magnetic pulling force upon the ferromagnetic metal surface, the strains are concentrated in a limited volume of the resilient material If the strains are too high, the resilient material will tear and break, and the magnets will be released through the torn opening in the sole, ultimately resulting in loss of traction, stability and creating a safety hazard for the worker. The likelihood of such failure increases with use on irregular surfaces and heat.

[0029] On uneven surfaces, such as corrugated steel sheets, the entire sole directly below a magnet is less likely to be in contact with the steel sheet surface. When the sole below a magnet is not locally in contact with the steel sheet surface, and even if the shoe as a whole is firmly pressed toward the steel sheet surface, the magnetic traction force will still pull on the sole below the magnet. Without the direct contact of the surface pushing back the sole in the opposite direction, only the parts of the resilient material of the sole beneath the magnet resists the magnetic pulling force and retains the magnet in place. The sole can therefore be stretched below the magnet and the strain level in that area of the resilient material of the sole will be high.

[0030] The durability is even more affected on hot surfaces. In a sunny day, a roof temperature can exceed 60°C. At such a temperature, the tensile strength of most rubbers typically used in outsoles is reduced significantly. This loss of tensile strength further increases the risk of a tear or break in an already thin and mechanically over-strained sole.

[0031] To maximize durability and resistance to tears, the present invention uses paramagnets associated with the magnets to spread out the strain over a much larger volume. Spreading the strain that way reduces its maximal value, and helps to keep it below the breaking point. The magnets are fixed or held in place within the sole by the force of magnetic attraction exerted by the paramagnetic plates positioned above them. These paramagnet plates serve as anchors for the magnets deep within the resilient material.

[0032] If properly designed, as discussed in the detailed description, the pulling force exerted by the paraniagnets on the magnet exceeds that of the magnetic metal surface on the magnet. This prevents the strains from concentrating below the magnets. In fact, the strains are spread out onto the resilient material within a volume starting from the area surrounding the paramagnets and down to the bottom surface of the sole. Spreading the strains that way across the resilient material ensures that the level of strain is low enough throughout the volume of resilient material to avoid creating a tear in the flexible material.

[0033] The present invention also includes a magnet comprising a magnet body and a bonded coating of an epoxy or other bonding material on the surface of the body. Advantageously, the sole is made of a rubber material molded over the epoxy-coated magnets. This creates a bond between the magnets and the rubber material, contributing to further dissipation of any remaining mechanical strains within the rubber material around each magnet.

[0034] Since extended usage and heat have a negative effect on the glue that is used in the average work shoe, the present invention also provides a solution to better withstand heat and wear. In fact, heat reactivates the glue, making it soft or even liquid and unable to keep a strong bond between the sole and the vamp. In the present invention, the polymerization and/or curing of the resilient material in contact with the vamp eliminates the need for glue, and provides a bond that wall last longer than glue and will be much less impacted by heat, since rubber does not melt with heat.

[0035] The present invention also features an improved resistance to tears and tears propagation when compared to state-of-the-art work shoes. Indeed, reinforcing the resilient material with a traction resistant fabric can inhibit or prevent tear propagation. Encountering sharp objects on the ground of a building site is fairly common, and stepping on these can create cuts on the outsole of the shoe. Over time, these cuts tend to extend and grow when the work shoe is used. Reinforcing the sole, and specifically the outsole with traction resistant fabrics prevents the extension growth of such cuts, leaving the sole harmless of structural and deeper damages

[0036] The present invention finally features an improved resistance to cuts, especially those under or around the magnets. In fact, in state of the art such as US 10,897,948 B2, a cut under a magnet creates an opening through which the magnet can be accessed Because of the lack of bonding between the magnet and the inner side of the insole, the magnet can be easily revealed when the sole is flexed and can even fall out of its cavity effortlessly if the cut is large enough. This invention solves this issue by firmly bonding the magnets to the material that surrounds them. To this end, a preferred embodiment combines a polyurethane rubber material with epoxy-coated magnets. During the material solidification process, also called rubber vulcanization, polyurethane will bond to epoxy, making it nearly impossible to remove a magnet from within the sole in case of a cut, even large under the magnet. This bond also insures that the magnets are not exposed even when flexing the sole even if the sole has a cut under the magnet. Since the rubber layer beneath the magnets is relatively thin, it is important to encompass risks of cuts deep enough to reach the magnets. Brief description of the drawings

[0037] An embodiment will now be described, by way of an example only, with reference to the accompanying drawings wherein:

[0038] FIG. 1 is a side bottom view of the magnetic shoe.

[0039] FIG. 2 is a view of the magnetic shoe taken over a sectional plan through the line

2-2.

[0040] FIG. 3 is a view of the magnetic shoe taken over a sectional plan through the line

3-3.

[0041] FIG. 4 is a sectional view through a heel portion of the shoe.

[0042] FIG. 5 is an exploded view of a magnetic shoe showing the vamp, the sole and the elements embedded within the sole.

[0043] FIG. 6 is a view of a magnet and a bonded coating.

[0044] FIG. 7 is a bottom side rear view of the magnetic shoe associated with the removable protective device.

[0045] FIG. 8 is a view of the removable protective device from the side top

[0046] FIG. 9 is a sectional view of the removable protective device through a vertical plane.

[0047] FIG. 10 is a side bottom view ⁷ of the magnetic shoe associated with its removable protective device.

Detailed Description of Preferred Embodiments

Definitions:

[0048] As used herein, a “vamp” is the part of the shoe that covers the sides and top of the wearer’s foot, and consists of the part of the shoe above the sole.

[0049] As used herein, a resilient material is a material that can absorb energy when deformed elastically and release the energy upon unloading, while maintaining its original shape. Resilient materials that can be used in sole making include but are not limited to cork, rope, leather, and elastomeric materials. Elastomeric materials in sole making include but are not limited to thermosetting polymers. A thermosetting polymer is obtained by curing a liquid prepolymer resin. Once hardened, a thermoset cannot be melted for reshaping.

[0050] FIG. 1 shows a magnetic shoe 1 of the present invention comprising a vamp 5, a sole 10 having a bottom surface 12. The sole member 14 includes a plurality of magnets contained within a resilient material that forms the sole member 14.

[0051] FIG. 2 illustrates a sectional plan view taken through the sole 10 through line 2-2 of FIG. 1, which lies in a plane that is parallel with the bottom surface 12 of the sole 10 In the illustrated embodiment, the plane of the section line is shown passing through the plurality of magnets 25, which are arranged in a pattern in the forefoot portion 14 and the heel portion 16 of the sole 10. Shown in dashed lines in FIG. 2 are the plan positions of a plurality of paramagnets 30, which are positioned vertically above the magnets 25 and the sectional line 2-2.

[0052] FIG. 3 illustrates a sectional plan view taken through the sole 10 through line 3-3 of FIG. 1, which lies in a plane that is parallel with the bottom surface 12 of the sole 10, and vertically above the sectional line 2-2. In the illustrated embodiment, the plane of the section line is shown passing through the plurality of paramagnets 30, which are arranged in a pattern in the forefoot portion 14 and the heel portion 16 of the sole 10. Shown in dashed lines in FIG. 3 are the plan positions of the plurality of magnets 25, which are positioned vertically below the paramagnets 30 and the sectional line 3-3.

[0053] The plurality of magnets 25 includes three magnets 25a (FIG. 2) in the heel portion 16 are shown in a column extending along the length (y direction) of the sole. The three magnets are spaced apart and separate by a space equivalent to about a diameter or more of the magnet 25a, and extend from the heel area to the arch area of the heel portion 16 of the sole. In other embodiments, the magnets 25a can be spaced apart more closely, or a second column of magnets can extend side-by-side with the first column.

[0054] Preferably, the magnet 25 is a neodymium magnet. This choice provides a good balance between strength, cost and durability.

[0055] The plurality of paramagnets 30 include a rectangular paramagnet 30a (FIG. 3) in the heel portion 16, aligned along the length (y direction) of the sole 10 and overlapping the column of magnets 25a. The paramagnet 30a extends from the heel area to the arch area of the heel portion 16 of the sole, and overlaps and extends laterally and longitudinally beyond the circumferences of the three magnets 25a. Alternatively the paramagnet 30a can comprise two or more individual paramagnets, each on top of a single magnet 25a.

[0056] The magnets 25 also include four magnets 25b arranged as pairs of magnets in two parallel rows in the ball area of the forefoot portion 14. Each pair of magnets 25b are spaced apart laterally (x direction) and separated by a space equivalent to a diameter or more of the magnet 25b, and each is positioned about half the distance between the longitudinal centerline 99 and the lateral outer edge of the sole 10. The two rows of magnets are spaced apart longitudinally (y direction) and separated by a space equivalent to a diameter or more of the magnet 25b. In other embodiments, the magnets 25b can be spaced more closely, or only one row or a third row (or more) of magnets can be used, or a third or more magnet can be used in either or both rows.

[0057] The plurality of paramagnets 30 also includes a pair of rectangular paramagnets 30b (FIG. 3) in the ball area of the forefoot portion 14, aligned transverse to the length (y direction) of the sole 10, and each overlapping a row of magnets 25b The paramagnets 30b extend from near the inner lateral edge to near the outer lateral edge of the forefoot portion 14 of the sole, and overlaps and extends laterally and longitudinally beyond the circumferences of the two pairs of magnets 25b.

[0058] As shown in FIG. 1, the natural line of foot flexion 7 takes place in the forefoot In various embodiments, the paramagnets 30 extend parallel to the axis of toe flexion 7, which does not inhibit or prevent the magnetic shoes from flexing along axis of toe flexion 7. In various embodiments, the paramagnets 30 located under the forefoot are not wider (in the y direction) than about 30 ram.

[0059] The magnets 25 also include a pair of magnets 25c arranged in a row in the toe area of the forefoot portion 14. The pair of magnets 25b are spaced apart laterally (x direction), and each magnet 25c is positioned about half the distance between the longitudinal centerline 99 and the lateral outer edge of the sole 10. In other embodiments, the magnets 25b can be spaced more closely, or only one magnet may be used.

[0060] The plurality of paramagnets 30 also includes a rectangular paramagnet 30c (FIG.

3) in the toe area of the forefoot portion 14, aligned transverse to the length (y direction) of the sole 10, and overlapping the pair of magnets 25c. The paramagnet 30b extends from near the inner lateral edge to near the outer lateral edge of the forefoot portion 14 of the sole, and overlaps and extends laterally and longitudinally beyond the circumferences of the pair of magnets 25c.

[0061] As shown in FIG. 3, the outer periphery of the paramagnet 30c positioned in the toe area of the forefoot portion 14 can have beveled comers to accommodate the tapering of the sole 10 in the top area.

[0062] FIG. 4 illustrates a sectional view through a heel portion 16 of the sole member 14. The resilient material 20 surrounds and encases, to hold in place, a magnet 25 and a paramagnet 30 associated magnetically with the magnet 25. The laws of magnetism are such that the paramagnet 2 exerts a pulling force on the magnet 25 directed transverse (z-direction) to the plane of the magnet 25 (lying in the x-y plane). Similarly, there is also a pulling force exerted by a magnetic metal surface M on the magnet 25. Advantageously this creates traction and stability for the magnetic shoe 1.

[0063] In various embodiments, the magnetic pulling force exerted by a paramagnet 30 on the magnet 25 is greater than the magnetic pulling force exerted on the magnet 25 by the metal surface Ml upon which the sole 10 is placed, and the magnetic pulling force exerted by the paramagnet 30 does not restrain or reduce the magnetic pulling force exerted by the metal surface M. These features are achieved by using a thicker, stronger, or larger paramagnet 30, or by positioning the paramagnet 30 at a closer distance in the z direction to the magnet 4.

[0064] In an even preferred embodiment, the paramagnet 30 is a ferromagnet. The magnet 25 typically has a cylindrical or rectangular shape, and the paramagnet 30 typically has a planar circular or planar rectangular shape The periphen,' of the paramagnets 30 also preferably has rounded corners, and rounded top and bottom edges, to avoid a sharp edge or point that might initiate or propagate a cut or tear in the resilient material 20.

[0065] In a preferred embodiment, the lateral outer periphery 32 of the paramagnet 30a laterally extends beyond the lateral outer periphery 27 of the magnet 25a in order to create a circumferential shoulder 18 within the resilient material 20 that serves as a vertical support that inhibits or prevents vertical movement of the paramagnet 30a toward the bottom surface 12 of the sole 10. The magnet 25a, which is magnetically attracted to the paramagnet 30a, is thus maintained within the resilient material by the force of magnetic attraction exerted by the magnet 25a onto the paramagnet 30a supported by the shoulder 18.

[0066] In another preferred embodiment, the distance D2 between the magnet 25 and the metal surface M is several times greater than the distance DI between the magnet 25 and the paramagnet 30. In a more preferred embodiment, the magnetic pulling force exerted by the paramagnet 30 on the magnet 25 is sufficient to restrain the magnet 25 in its place, even in presence of the pulling force exerted on the magnet 25 by the metal surface M. The magnet 25 is magnetically bound to the paramagnet 30. These features result in significantly lower levels of strain exerted by the magnet 25 on a traction-resistant fabric layer 40 below the magnet 25 and the surrounding resilient material 20.

[0067] The layer of resilient material 20 between the magnet 25 and the bottom surface 12 of the outer layer of the sole 10 (distance D2 in FIG. 4) is up to about 10 mm. The thinner the layer of resilient material, the stronger the magnetic pulling force, while the thicker the layer of resilient material, the more durable and resistant the resilient material will be to use-induced abrasion, wear and tearing.

[0068] Preferably, this distance is from about 1 mm to about 4 mm, and can include about 1 mm to about 3 mm, about 1 mm to about 2 mm, about 2 mm to about 3 mm, and about 3 mm to about 4 mm .

[0069] The magnetic pulling force of the metal surface M on the combined magnet 25 and paramagnet 30 exerts stress on the material of the resilient material 20 the magnet 2 and paramagnet 30. In various embodiments, the area of surface contact between the paramagnet 30 and the resilient material 20 is greater than the area of surface contact between the magnet 25 and the resilient material 20, which enables the paramagnet 30 to anchor and stabilize the magnet 25 within the resilient material 20. The combination of the magnet 25 with a paramagnet 30 as described reduces mechanical strain within the resilient material 25 surrounding the combination, and in particular, surrounding the magnet 25, as compared to a greater strain that results when using only a magnet.

<Coated Magnet > [0070] Another invention provided herein is magnet body having a coating comprising a bonding material. The bonding material is used between the magnet and the surrounding rubber material, and more specifically, a bonding material applied to the outer surface of the body of the magnet to improve the bonding of resilient material to the magnet body. This can be achieved by molding the resilient material around the coated magnet.

[0071 ] FIG. 6 illustrates a coated magnet 125 comprising a body of a magnet 25 with a coating 50 bonded to the outer surfaces of the body. In various embodiments, the bonded coating is an epoxy material. The use of a coated magnet provides a stronger bonding of the resilient material to the body of magnet, which renders the resilient material (for example, rubber) beneath the coated magnet 125 less susceptible to cuts and other mechanical stresses.

[0072] FIG. 5 is an illustration of the positioning of the magnet and paramagnet elements in the complete magnetic shoe, including the vamp 5, a shock absorber 55, the paramagnets 30 as arranged in FIG. 3, a plurality of magnets 25 as arranged in FIG. 2, a traction-resistant fabric 40, and the sole 10 comprising the resilient material 29. A shock absorber 55 is positioned in the heel portion of the sole 10 that advantageously reduces the volume of resilient material 1 required to fill the heel portion 16 of the sole 10, while also elevating the heel of the wearer’s foot Elevated heels portions give additional comfort to the worker, especially when working on an inclined roof facing the roof ridge.

[0073] In various embodiments, the combined magnetic pulling force of the plurality of magnets 25 is between 300 Newtons (N) and 3,000 N, per shoe. Higher values could make walking difficult, or would require placing the magnets deep inside the sole (separated from the bottom surface 12 of the sole 10) to reduce their magnetic pulling force on the metal surface M. Placing the plurality of magnets 25 deeper in the sole 10 would ultimately add cost and weight. Lower magnetic pulling force values could lead to insufficient pulling force to ensure the worker’s stability and grip. Alternatively, lower magnetic pulling force values could provide sufficient magnetic pulling force with a potentially-compromising reduction in the thickness of rubber below the plurality of magnets 25, which could more quickly wear out with use-induced abrasion, and thus shortening the product life.

<Removable Protective Device> [0074] Another invention described herein is a removable protective device that can be associated with the magnetic shoe 1 to protect the outer sole 10 of the magneti c shoe 1 when worn on non-magnetic surfaces. FIG. 7 illustrates a removable protective device 60 that can be attached to sole 10 of the magnetic shoe 1. In an advantageous embodiment, the shape and size of the protective device 60 and the sole 10 of the magnetic shoe 1 are complementary to not only allows easy fitting but also to protect the entire sole surface of the magnetic shoe 19.

[0075] The protective device 60 shown in perspective view in FIG, 8 includes a flexible cover sole 62 and one or more, and typically a plurality of, protective paramagnets 66 fixed to the cover sole 62. The protective paramagnets 66 are shown in dashed lines to show their positioning relative to the protective sole 62, FIG. 9 is a sectional elevation view along the longitudinal (y) axis of the protective device 60, illustrating the positioning of the protective paramagnets 66, according to the illustrated advantageous embodiment, embedded within the material of the cover sole 62 Each of the protective paramagnets 66 are oriented in a plane parallel with the plane of the upper surface of the protective sole 62.

[0076] The protective paramagnets 66 attach magnetically and maintain the positioning of the protective device 20 to the magnetic shoe 1 . The flexible cover sole 62 is applied to the bottom surface 12 of the soles 10 when the wearer has moved off of the metal surface M, and is walking on the ground or other area of a construction site. When positioned on the bottom surface of the sole 10 of the magnetic shoe 1, the protective paramagnets 66 align in registry with each of the magnets 25 embedded within the sole 10, to both magnetically fix the protective device 60 to the sole 10, and limit the range of magnetic forces of the magnets 25 within the sole 10 to attract magnetic objects on or in the ground.

[0077] The protective device 60 provides at least two benefits. First, the flexible cover sole 62 protects sacrificially the bottom surface 12 of the sole 10 of the magnetic shoe 1 from sharp objects on the ground of other walking surfaces, which might cut. into the bottom surface of the sole. The protective paramagnets 66 also limit the range of the magnetic field generated by the magnetic shoe and thus reduce the magnet's propensity to pick up ferrous objects present on the ground such as nails and staples. The protective paramagnets 66 are, according to the illustrated advantageous embodiment, ferromagnetic and embedded in the material of the flexible sole 17. [0078] The protective device 60 also can include a plurality of retaining protrusions which are positioned along the periphery of, and extend vertically above the upper surface of, the cover sole 62. The retaining protrusions include a pair of toe-retaining protrusions 64 that extend along the curved periphery' in the toe portion of the cover sole 62, to confront the forefoot portion 14 of the sole 10 of the magnetic shoe 1, and a heel -retaining protrusion 65 that extends along the curved periphery in the heel portion of the cover sole 62, to confront the heel portion 16 of the sole 10 of the magnetic shoe 1. The positioning and the length of the heel -retaining protrusion 65 at the rear make it possible to position the heel of the magnetic shoe 1 first on the cover sole 62 of the device 20, which allows a positioning that is sufficiently precise and follows the ergonomic movement of walking where the heel first will touch the ground before the forefoot portion 16 of the magnetic shoe 1 is completely included in the space between the toe-retaining protrusions 64.

[0079] The protective device 60 also can include a means for aiding the removal of the protective device 60 from the magnetic shoe 1. FIG. 7 illustrates the removal means as a tongue 68 that, according to an advantageous embodiment, extends from the rear of the cover sole 62 of the protective device 60. The tongue 68 allows the wearer to remove the protective device 60 using only his or her other foot and while standing. To detach the protective device 60 from the magnetic shoe 1, the wearer keeps his wearing foot flat on the ground, and with the toe of the other foot presses down on the tongue 68. By then lifting the heel portion 16 of the wearing foot, the protective device 60, being held to the ground by the tongue 18, can overcome and be peeled away from the magnetization of the magnets 25 in the shoe sole 10, to release the magnetic shoe 1 from the protective device 60.

[0080] FIG. 10 illustrates the removable protective device 60 in place on the magnetic shoe 1. In an advantageous embodiment, the clearance width between the toe-retaining protrusions 64 and the forefoot portion 14 of the sole 10 of the magnetic shoe 1 is sufficient to allow easy positioning and placement of the magnetic shoe 1 onto the protective device 60, though sufficiently narrow to ensure lateral support of the protective device 60. In some embodiments, the clearance width of from about 1 mm to about 5 mm.

[0081] In another embodiment, the clearance between the removable protective device 60 and the magnetic shoe I is inferior to 1 mm. This allows for a tighter bond between the two elements and makes such bond more secure. Sliding of the magnetic shoe I on the removable device 60 is prevented. To allow an easy placement of the magnetic shoe 1 on the removable protective device 60, the top of the protrusion 64 and 65 is beveled toward the inside.

[0082] In another embodiment, the toe-retaining protrusions 64 are included in a single large protrusion going through all the toe area. This enhances the resilience of such protrusion.