Patent Publication Number: US-11641907-B2

Title: Footwear

Description:
The present invention relates to generally to the field of footwear with interchangeable heels, and in particular articles of footwear that allow for the heel to be interchanged quickly and conveniently. 
     Either for aesthetic or for practical reasons it is desirable to be able to alter the appearance of articles of footwear. A wearer may wish to change the appearance of their footwear to suit a different occasion. They may wish to match their footwear to a particular outfit or style to keep up with current trends. The heel portion of a pair of shoes may become damaged and need to be replaced or repaired. 
     There are many patent publications which relate to an interchangeable heel for a shoe (also known as an interchangeable shoe heel cover). Generally, the disclosed solutions to the problem of providing a shoe with an interchangeable shoe heel suffer from the problems that the shoe heels do not pass SATRA Test TM113 for “Measurement of the Strength of Attachment of Heels to Footwear and the Backpart Rigidity of Such Footwear” (1996) and are not suitable for commercialisation because part or all of the mechanism is provided on the replaceable heel cover. As a result, the cost of manufacture of the replaceable heel cover becomes too expensive in comparison to the expected price point for the consumer. 
     According to the invention there is provided an interchangeable heel for a shoe wherein the interchangeable heel comprises a removable heel sleeve and a heel post which is mounted on the shoe wherein the heel sleeve is releasably mounted on the heel post by an opposed lock mechanism which comprises a catch mechanism on one side of the interchangeable heel and a biasing mechanism on an opposite side of the interchangeable heel wherein the biasing mechanism comprises a biasing member which is provided on the heel post wherein the biasing member is arranged to engage the removable heel sleeve. 
     According to the invention there is also provided a shoe comprising an interchangeable heel according to the invention. 
     According to the invention there is further provided a removable heel sleeve for use in the interchangeable heel according to the invention wherein the heel sleeve forms a catch formation or a catch aperture to form part of the catch mechanism for engaging the heel post of the interchangeable heel according to the invention. 
     Advantages of the invention include that the shoe to which the interchangeable heel is attached generally fails in the SATRA Test TM113 before the interchangeable heel; the interchangeable heel withstands a tensile force of at least 600N; that the replaceable or interchangeable heel sleeve which may be used to change the appearance of a shoe is relatively cheap to manufacture because the biasing member which is the main functional part of the opposed lock mechanism is provided on the heel post; and that the heel sleeve may be moulded from a thermoplastic material and comprises no moving parts. 
     In some embodiments, the heel catch mechanism may comprise a catch aperture and a catch formation. In some embodiments, lock mechanism comprises a lock formation for engaging the biasing member provided on the removable heel sleeve, the biasing member, and a heel post lock aperture shaped to receive the biasing member. 
     In some embodiments, the opposed lock mechanism consists of a catch mechanism on one side of the interchangeable heel and a biasing mechanism on an opposite side of the interchangeable heel. In some embodiments, the opposed lock mechanism has (or consists of) a single catch mechanism on one side of the interchangeable heel and a single biasing mechanism on an opposite side of the interchangeable heel. In some embodiments, the interchangeable heel has a single opposed lock mechanism. In some embodiments, the single opposed lock mechanism consists of a catch mechanism on one side of the interchangeable heel and a biasing mechanism on an opposite side of the interchangeable heel. In some embodiments, the single opposed lock mechanism has (or consists of) a single catch mechanism on one side of the interchangeable heel and a single biasing mechanism on an opposite side of the interchangeable heel. 
     In some embodiments, the interchangeable heel may comprise an upper heel and a lower heel and the opposed lock mechanism may be provided on the upper heel. In some embodiments, the opposed lock mechanism may be provided on the front and rear sides of the heel. In some embodiments, the catch mechanism may be provided on the rear side of the heel and the biasing mechanism may be provided on the front side of the heel. Advantages of such an arrangement include that the typical forces exerted on a shoe heel such as a rearward force applied to the heel tip has the effect of increasing the engagement of the catch mechanism, particularly when the catch mechanism is provided on the upper heel. 
     In some embodiments, the catch mechanism may comprise a catch formation provided on one of the heel post or heel sleeve and a catch aperture shaped to receive the catch formation formed by the other of the heel post or heel sleeve. In some embodiments, the catch mechanism may comprise a catch formation provided on the heel sleeve and a catch aperture formed by the heel post. 
     In some embodiments, the biasing member may be in the form of a leaf spring or a coil spring. In some embodiments, the biasing mechanism may comprise the biasing member and a lock aperture formed on heel post and shaped to receive the biasing member. In some embodiments, the biasing member may be in the form of leaf spring and may be attached to the heel post above the lock aperture. In some embodiments, the biasing member may be in the form of a coil spring and may be attached within lock aperture. In some embodiments, the biasing member may be formed from a tempered metal such as spring steel, e.g. stainless spring steel. 
     In some embodiments, the heel post may have an angled head surface for engaging the shoe sole and the catch aperture may be provided on the rear side of the angled head surface. 
     In some embodiments, the lock aperture and biasing member are provided on a curved heel breast on the upper part of heel post. 
     In some embodiments, the removable heel sleeve forms a heel sleeve aperture for receiving the heel post. In some embodiments, the removable heel sleeve forms a recess for receiving the heel tip. 
     In some embodiments, the removable heel sleeve may have an angled head for engaging the shoe sole and the catch formation may be provided on the rear side of the angled head. In some embodiments, the catch formation may be formed from a thermoplastic material such as an engineering thermoplastic, e.g. polyoxymethylene (POM), acrylonitrile butadiene styrene (ABS), polycarbonate, and/or polyamide (nylon, such as nylon 6 or nylon 66). 
     In some embodiments, the removable heel sleeve may have a lock formation for engaging the biasing member of the biasing mechanism. In some embodiments, the lock formation may be provided on curved heel breast of removable heel sleeve. 
     In some embodiments, the interchangeable heel comprises an anti-twist mechanism which comprises one or more guidance slots provided on one of the heel post and heel sleeve and one or more guidance formations provided on the other of the heel post and heel sleeve. In some embodiments, the guidance slots may be shaped to receive the guidance formations and to facilitate movement of the heel sleeve to remove it from the heel post but to prevent other movement of the heel sleeve. 
     In some embodiments, the one or more guidance slots may be provided on the heel post. In some embodiments, a guidance slot is provided on each side of heel post lock aperture. In some embodiments, the one or more guidance slots have an aperture which is orientated towards the heel tip such when the removable heel sleeve is slid onto the heel post, the guidance formations are inserted into the guidance slots. In some embodiments, the heel sleeve has an angled head and the one or more guidance formations are provided on the heel breast side of the angled head of removable heel sleeve. 
     In use, the opposed lock mechanism are engaged when the heel sleeve is mounted on heel post by sliding the heel sleeve over the heel post such that the catch mechanism is engaged. The heel sleeve engages the heel post biasing member such that the biasing member urges the heel sleeve in a direction away from the catch mechanism so as to activate the catch mechanism. To release the opposed lock mechanism, pressure may be applied to a part of the heel sleeve near the biasing member to force the biasing member against the heel post such that the catch mechanism is disengaged and the heel sleeve may be removed from the interchangeable heel. 
     In some embodiments, the heel post may be formed from a moulded resilient plastics material. In some embodiments, the heel post may form a heel post pin channel for receiving the heel pin. 
     In some embodiments, the shoe may have a shoe body and a shoe sole. In some embodiments, the interchangeable heel may comprise a shoe heel pin to provide structural strength for the heel; the shoe heel pin may be made from steel. In some embodiments, the interchangeable heel may comprise a shoe heel tip; the shoe heel tip may be formed from rubber and may provide a non-slip lower surface for the heel. 
     In some embodiments, the interchangeable heel may be a high, mid or low heel. In some embodiments, the interchangeable heel may be in the form of a stiletto, cone, spool, chunky (also known as a block), wedge (where the space  24  between the heel  10  shown in  FIG.  1    and the sole  16  is filled by the wedge heel), or comma heel. 
    
    
     
       The invention will now be illustrated with reference to the following Figures of the accompanying drawings which are not intended to limit the scope of the claimed invention: 
         FIG.  1    shows a schematic side view of a high heeled shoe incorporating the interchangeable heel according to the invention; 
         FIG.  2    shows a partial schematic side view of a high heeled shoe incorporating the interchangeable heel according to the invention where the heel sleeve has been removed; 
         FIG.  3    shows a schematic cross-sectional view of the interchangeable heel according to the invention; 
         FIG.  4    shows a schematic isometric view of a shoe heel post for use in the interchangeable heel according to the invention; 
         FIG.  5    shows a schematic rear elevation of the shoe heel post for use in the interchangeable heel according to the invention; 
         FIG.  6    shows a schematic isometric view of a heel sleeve for use in the interchangeable heel according to the invention; and 
         FIG.  7    shows a schematic cross-sectional view of a heel sleeve for use in the interchangeable heel according to the invention. 
     
    
    
     An interchangeable heel according to the invention is indicated generally at  10  on  FIGS.  1  and  3    of the accompanying drawings. Interchangeable heel  10  is shown in  FIG.  1    mounted on a high heel shoe  12  which has a shoe body  14  and a shoe sole  16 . Shoe body  14  comprises the usual parts of an upper part of a shoe such as a vamp, quarter, toe cap, lining, throat etc and may be formed from a natural or synthetic material. The present invention does not affect the design of the shoe body  14 : generally speaking, any design of the shoe body  14  may be used with the interchangeable heel  10 . 
     Interchangeable heel  10  is in the shape of a high heel having a head in the form of an upper heel  26  and a body in the form of a lower heel  28 . Upper heel  26  has an inverted truncated pyramidal shape having an angled head surface  35  which is shaped to engage the shoe sole  16 . In use, the shoe  12  is attached to angled head surface  35  of interchangeable heel  10  by means of self-tapping screws (not shown). Upper heel  26  has a concave heel breast  22  (which is the front side of the upper heel  26  which faces the shoe sole  16 ). Lower heel  28  which has a tubular shape with a substantially square cross-section. The shoe  12  has a shoe back  13  and a space  24  between the heel and the sole. 
     As shown in  FIG.  3   , interchangeable heel  10  comprises a removable heel sleeve  30 , a shoe heel post  34 , a shoe heel pin  36 , and a shoe heel tip  18  wherein the removable heel sleeve  30  is removable from the shoe heel post  34  by means of an opposed lock mechanism  41  which is provided on the upper heel  26 . In this way, the removable heel sleeve  30  is an interchangeable removable heel sleeve  30 . Removable heel sleeve  30  may be formed from a moulded plastics material. Shoe heel pin  36  is typically made from steel and provides structural strength for the heel  10 . Shoe heel tip  18  is generally formed from rubber and provides a non-slip lower surface for the heel  10 . 
     In an alternative embodiment, the interchangeable heel  10  may also be used on a shoe  12  having a different heel height, for example a mid or low heel having a shorter lower heel  28  with a shorter heel pin  36  wherein the lower parts  26 , 126  of the heel post  34  and removable heel sleeve  30  are shaped accordingly. It will be appreciated that the function of the invention is not dependent upon the external shape of the removable heel sleeve  30 . The interchangeable heel  10  may be used with any external shape of removable heel sleeve  30 . In an alternative embodiment, the interchangeable heel  10  or the removable heel sleeve  30  may be in the form of a stiletto, cone, spool, chunky (also known as a block), wedge (where the space  24  between the heel  10  shown in  FIG.  1    and the sole  16  is filled by the wedge heel), or comma heel. In an alternative embodiment, the removable heel sleeve  30  may be formed from metal (such as aluminium), a synthetic material, and/or a natural material (such as wood). 
     Shoe heel post  34  is shown in more detail in  FIGS.  4  and  5   . Shoe heel post  34  has an upper part  126  and a lower part  128 . Shoe heel post  34  is formed from a moulded resilient plastics material. The upper and lower parts  126 , 128  of heel post  34  form a heel post pin channel  39  for receiving the shoe heel pin  36 . The upper part  126  of heel post  34  provides part of the opposed lock mechanism  41 . On the shoe back side  13  of the angled head surface  35  of the upper part  126  of heel post  34 , a heel post catch aperture  62  is provided which receives a heel sleeve catch formation  64 . On the opposing curved heel breast  22  on the upper part  126  of heel post  34 , a heel post lock aperture  37  and a heel post biasing member  46  are provided. The heel post biasing member  46  is in the form of a metal leaf spring which is attached to the heel post  34  in biasing member slot  25  which is positioned above heel post lock aperture  37 . The heel post lock aperture  37  is shaped to receive the heel post biasing member  46  in use. For example, the heel post biasing member  46  may be formed from a tempered metal such as spring steel, e.g. stainless spring steel. Heel post biasing member  46  is arranged to provide a biasing force in the direction of the shoe sole  16  so as to engage the removable heel sleeve  30 . To each side of heel post lock aperture  37 , heel post guidance slots  74  are formed which are shaped to receive heel sleeve guidance formations  72  on the removable heel sleeve  30 . Heel post guidance slots  74  each have an aperture which is orientated downward such when the removable heel sleeve  30  is slid onto the heel post  34 , the heel sleeve guidance formations  72  are inserted into the guidance slots  74 . In an alternative embodiment, the heel post biasing member  46  may be in the form of a coil spring. 
     Removable heel sleeve  30  is shown in more detail in  FIGS.  6  and  7   . Removable heel sleeve  30  has an upper part  26  and a lower part  28 . Upper part  26  of removable heel sleeve  30  forms a heel sleeve aperture  32  for receiving the heel post  34 . The base of the lower part  28  of removable heel sleeve  30  forms a heel sleeve recess  33  for receiving heel tip  18 . On the upper part  26  of removable heel sleeve  30 , corresponding parts of the opposed lock mechanism  41  are provided. On the shoe back side  13  of the angled head  35  of upper part  26  of removable heel sleeve  30 , a heel sleeve catch formation  64  is provided which is shaped to engage with the heel post catch aperture  62 . Heel sleeve catch formation  64  is formed from a thermoplastic material such as an engineering thermoplastic, e.g. polyoxymethylene (POM), acrylonitrile butadiene styrene (ABS), polycarbonate, and/or polyamide (nylon, such as nylon 6 or nylon 66). On the opposing side of the upper part  26  of removable heel sleeve  30 , a heel sleeve lock formation  56  is provided on curved heel breast  22  to engage with the heel post biasing member  46 . On the heel sole side of angled head  35  of upper part  26  of heel sleeve, heel sleeve guidance formations  72  are provided to each side of heel sleeve lock formation  56 . Heel sleeve guidance formations  72  are fin-shaped so as to be suitable for engaging heel sleeve guidance slots  74  on the heel post  34 . 
     The opposed lock mechanism  41  comprises a heel catch mechanism  60  which is provided on the rear side of the heel  10  and a heel lock mechanism  45  which is provided on the heel breast  22  (in other words the front side of the heel  10 ) such that they are provided on opposite sides of the interchangeable heel  10 . Heel catch mechanism  60  comprises the catch aperture  62  formed by the heel post  34  and the catch formation  64  on the removable heel sleeve  30 . Heel lock mechanism  45  comprises heel sleeve lock formation  56 , heel post biasing member  46 , and heel post lock aperture  37 . The heel post guidance slots  74  and heel sleeve guidance formations  72  form an anti-twist mechanism indicated generally at  71  on  FIG.  3   . The guidance slots  74  and guidance formations  72  are arranged to have a length which is substantially parallel to a line drawn between the heel catch mechanism  60  and the heel lock mechanism  45  such that the anti-twist mechanism  71  does not present any resistance to any movement of removable heel sleeve  30  along that line to disengage removable heel sleeve  30  from heel post  34  but the anti-twist mechanism  71  otherwise provides resistance to any other movement of removable heel sleeve  30  in relation to heel post  34 . 
     In an alternative embodiment, heel catch mechanism  60  may comprise a catch aperture  62  which is formed on an internal surface of removable heel sleeve  30  and a catch formation  64  which is provided on the heel post  34 . 
     In use, the opposed lock mechanism  41  and the anti-twist mechanism  71  are engaged when the removable heel sleeve  30  is mounted on heel post  34 . The heel sleeve lock formation  56  engages the heel post biasing member  46  such that the biasing member  46  is forced into the heel post lock aperture  37  to activate the heel lock mechanism  45 . The heel sleeve catch formation  64  engages with the heel post catch aperture  62  to activate the heel catch mechanism  60 . The heel sleeve guidance formations  72  engage with the heel post guidance slots  74  such that the removable heel sleeve  30  cannot be rotated relative to the heel post  34 . The biasing member  46  urges the heel sleeve lock formation  56  in the direction of the shoe sole  16  such that the biasing member  46  urges the heel sleeve catch formation  64  to engage the heel post catch aperture  62 . 
     To release the opposed lock mechanism  41 , pressure may be applied to the heel sleeve lock formation  56  to force the heel post biasing member  46  further into the heel post lock aperture  37  and at the same time the removable heel sleeve  30  is rotated away from the heel sole  16  such the heel sleeve catch formation  64  disengages the heel post catch aperture  62  such that the removable heel sleeve  30  may be removed from the heel post  34  such that the heel sleeve guidance formations  72  are slid out of heel post guidance slots  74 . 
     One of the advantages of the interchangeable heel  10  according to the invention is that it passes the SATRA TM113 Heel Attachment test protocol (1996). In this test, the shoe  12  shown in  FIG.  1    is mounted in a tensile testing machine by attaching the lower part  28  of the heel  10  to an upper clamp attachment  20 , just above shoe heel tip  18  and attaching the sole  16  to a lower clamp  21 . A reference distance between the shoe heel tip  18  and the lower clamp  21  is measured and recorded as [D0]. The tensile testing machine is then operated at a jaw separation rate of 100±10 mm/min to apply a force to move heel  10  away from shoe sole  16  until a force of 200N has been applied. The reference distance is measured again without releasing the force and is recorded as [D1]. The tensile testing machine is restarted and is operated until a force of 400N has been applied. The reference distance is measured again without releasing the force and is recorded as [D2]. The tensile testing machine is operated again until the shoe  12  fails. 
     In a first test using the SATRA TM113 Heel Attachment test protocol (1996), the shoe sole  16  failed at a tensile force of 600N by buckling before heel  10  failed. This is believed to be because the application of force in a direction away from the shoe sole  16  to the lower part  28  of heel  10  creates a countervailing force to the upper part  26  of heel  10  such that the heel sleeve catch formation  64  is urged by that countervailing force to engage heel post catch aperture  62 . 
     In a second test using a shoe  12  with a different type of shoe sole  16  and the SATRA TM113 Heel Attachment test protocol (1996), the results were (with a tolerance of ±3%) initial distance DO was 143 mm, distance D2 measured at a force of 400N was 145 mm, the permanent set (calculated as the difference between D2 and D0) was 1.9%, and the maximum heel attachment load was 1005.3N. The second test was performed at 23° C.±2° C. and 50% rH±4% rH. These results pass the specifications set by UK shoe retailers who require a maximum 15% permanent set and a minimum 600N heel attachment load.