Patent Description:
Traditionally, placing footwear on a foot often requires the use of one or both hands to stretch the ankle opening of a footwear upper, and hold the rear portion during foot insertion, especially in the case of a relatively soft upper and/or an upper that does not have a heel counter secured to a flexible fabric rearward of the ankle opening.

Document <CIT> describes an article of footwear including an upper portion forming a shell, a sole, and a spring extending between the upper portion and the sole. The spring suspends the heel portion of the shell above the rearward portion of the sole and extends around the shell above the heel portion and further extends around the sole at the rearward portion of the sole. The spring has nesting spring portions at each of the medial and lateral sides of the article of footwear, which form hinges forward of the heel portion and the rearward portion at the lateral and medial sides of the article of footwear.

The claimed invention is defined by the features set forth in the appended independent claims <NUM> and <NUM>. Additional embodiments of the claimed invention are defined by the dependent claims <NUM>-<NUM> and <NUM>-<NUM>, respectively.

Heel spring devices for easing foot entry into an article of footwear are disclosed herein. Each of the heel spring devices may enable hands-free foot entry, such as by loading the heel spring device with the foot to access a foot-receiving cavity from a rearward position, and sliding the foot forward and downward into the foot-receiving cavity.

Within the scope of the present teachings, an article of footwear comprises a footwear upper including a flexible covering defining at least a portion of an ankle opening, a sole structure secured to and underlying the footwear upper, and a heel spring device. The heel spring device may comprise a control bar and a continuous base. The control bar may have a center segment secured to the flexible covering rearward of the ankle opening, a medial side arm extending from the center segment and secured to a medial side of the flexible covering, and a lateral side arm extending from the center segment and secured to a lateral side of the flexible covering. The base may support the control bar and may be connected to both of the medial side arm and the lateral side arm and secured to the sole structure. The control bar is biased to an unloaded position with the center segment a first distance from the base, and elastically bends under an applied force to a loaded position with the center segment a second distance from the base less than the first distance. The device stores potential energy, such as elastic energy and/or spring energy, potential energy, such as elastic energy and/or spring energy that returns the control bar to the unloaded position upon removal of the applied load, the flexible covering moving with the control bar.

Referring to the drawings, wherein like reference numbers refer to like components, <FIG> shows a device <NUM> for easing foot entry into an article of footwear <NUM> shown in <FIG>. The footwear herein is depicted as leisure shoes and athletic shoes, but the present teachings also include an article of footwear that is a dress shoe, a work shoe, a sandal, a slipper, a boot, or any other category of footwear.

The device <NUM> is configured to surround a portion of a foot-receiving cavity <NUM> at a heel region <NUM> of an article of footwear <NUM>, as shown in <FIG>. The heel region <NUM> generally includes portions of the article of footwear <NUM> corresponding with rear portions of a human foot, including the calcaneus bone, when the human foot is supported on the sole structure <NUM> in the foot-receiving cavity <NUM> and is a size corresponding with the article of footwear <NUM>. A forefoot region <NUM> of the article of footwear <NUM> (best shown with respect to article of footwear <NUM>, <NUM>, and <NUM> in <FIG>, <FIG>, and <FIG>) generally includes portions of the article of footwear <NUM> corresponding with the toes and the joints connecting the metatarsals with the phalanges of the human foot (interchangeably referred to herein as the "metatarsal-phalangeal joints" or "MPJ" joints). A midfoot region <NUM> of the article of footwear <NUM> (best shown with respect to article of footwear <NUM>, <NUM>, and <NUM> in <FIG>, <FIG>, and <FIG>) is disposed between the heel region <NUM> and the forefoot region <NUM> and generally includes portions of the article of footwear <NUM> corresponding with an arch area of the human foot, including the navicular joint.

The device <NUM> includes a control bar <NUM> that has a center segment <NUM>, a first side arm <NUM> extending downwardly and forwardly from the center segment <NUM>, and a second side arm <NUM> spaced from the first side arm <NUM> and also extending downwardly and forwardly from the center segment <NUM>. The first side arm <NUM> is a medial side arm and the second side arm <NUM> is a lateral side arm.

The device <NUM> also includes a base <NUM> supporting the control bar <NUM> and connected to the control bar <NUM> at a resiliently bendable junction 24A, 24B. The base <NUM> is continuous and extends between and connects to the first side arm <NUM> and the second side arm <NUM>. The base <NUM> is continuous, in that it is without breaks or connections through other components in extending from the first side arm <NUM> to the second side arm <NUM>. The base <NUM> has a center segment <NUM>, a first base arm <NUM>, and a second base arm <NUM> all disposed in a common plane. The common plane P is parallel with a horizontal surface when the base <NUM> of the device <NUM> rests on a horizontal surface, and is best indicated in <FIG> by the phantom line P that represents the plane perpendicular to the page of the drawing. The first base arm <NUM> is spaced apart from the second base arm <NUM> and both extend from the center segment <NUM> of the base <NUM>. As shown in <FIG>, the base <NUM> is slightly under the control bar <NUM>, lending stability to the device <NUM> during depression.

The junction 24A, 24B includes a first joint 24A at which the base <NUM> and the first side arm <NUM> connect, and a second joint 24B at which the base <NUM> and the second side arm <NUM> connect. The first joint 24A is the connection of the first base arm <NUM> to the first side arm <NUM>. The second joint 24B is the connection of the second base arm <NUM> to the second side arm <NUM>.

The control bar <NUM> has an arced shape from the first joint 24A to the second joint 24B. Similarly, the base <NUM> has an arced shape from the first joint 24A to the second joint 24B. With this arrangement, the control bar <NUM> and the base <NUM> are configured as a full elliptical leaf spring as described herein. The device may be referred to as a heel spring. Additionally, the device <NUM> is a single, unitary, one-piece component. For example, the device <NUM> may be injection molded as a single, unitary, one-piece component.

The control bar <NUM> is biased to an unloaded position shown in <FIG> and <FIG>. The unloaded position is also referred to herein as an unstressed position. The control bar <NUM> is internally biased to the unstressed position by its material in its formed state. Stated differently, the material of the control bar <NUM> is sufficiently rigid that it remains in the unstressed position in its natural state without external loads applied to it, and will return to the unstressed position after elastic bending due to its resiliency. In the unstressed position, the center segment <NUM> is a first distance D1 from the base <NUM>, as indicated in <FIG> by a distance D1 from the top of the center segment <NUM> to the bottom of the base <NUM>. The unstressed position is the position of the device <NUM> in a relaxed, unloaded state (i.e., without a vertical force applied to the control bar <NUM>). The control bar <NUM> can be depressed under an applied force F shown in <FIG>, representing the force applied by a foot <NUM> during insertion of the foot <NUM> into a foot-receiving cavity <NUM> (see <FIG>) of the article of footwear <NUM>. When loaded in this manner, the control bar <NUM> elastically bends to a loaded position in which the center segment <NUM> is a second distance D2 from the base <NUM>. The device <NUM> is indicated with phantom lines and reference number 10A in <FIG> when in the loaded position. The second distance D2 is less than the first distance D1. The difference between the distances D1, D2, is the deflection of the device <NUM>, which may be but is not limited to a deflection of <NUM>. The device <NUM> is configured so that when it is depressed under the force to the loaded position D2, it elastically bends at the junction 24A, 24B, storing elastic energy. When the force F is removed, the stored elastic energy returns the control bar <NUM> to the unstressed position. In <FIG>, only the device <NUM> and the sole structure <NUM> are shown. The upper <NUM> described herein is removed for clarity in showing the positions of the device <NUM>, 10A.

As shown in <FIG>, the article of footwear <NUM> includes a sole structure <NUM> and an upper <NUM> secured to the sole structure <NUM>. The sole structure <NUM> includes one or more sole components that may be sole layers <NUM>, such as an outsole, a midsole, or a unitary combination of an outsole and a midsole that may be referred to as a unisole. In <FIG>, the sole layer <NUM> may be a midsole or a unisole. The sole layer <NUM> underlies the upper <NUM>. A lower portion <NUM> of the footwear upper <NUM> is secured to the sole layer <NUM>, such as by adhesive or otherwise. The base <NUM> is secured to the sole layer <NUM> such as by bonding with adhesive, thermal bonding, or otherwise. The sole layer <NUM> may be formed with slight recesses on the outer surface shaped to allow the base <NUM> and junction 24A, 24B to partially nest in the recesses, thus being further supported by the sole layer <NUM>.

The flexible footwear upper <NUM> defines at least a portion of an ankle opening <NUM>. The base <NUM> underlies the control bar <NUM> and is secured to the footwear upper <NUM> with the first side arm <NUM> secured to a medial side <NUM> of the footwear upper <NUM>, and the second side arm <NUM> secured to a lateral side <NUM> of the footwear upper <NUM>. As best indicated in <FIG>, the base <NUM> extends around a rearmost portion of the footwear upper from the lateral side <NUM> to the medial side <NUM>. The center segment <NUM> of the control bar <NUM> is secured to the footwear upper <NUM> rearward of the ankle opening <NUM>. The device <NUM> may have a thinned portion <NUM> (best shown in <FIG>) that enables machine stitching of the upper <NUM> to the device at the thinned portion <NUM>.

The upper <NUM> may include a flexible covering <NUM> (also referred to as a flexible cover layer) for receiving and covering a foot <NUM> (indicated in <FIG>) to be supported on the sole layer <NUM>. For example, the flexible covering <NUM> may be a stretchable fabric, such as a <NUM>-way stretch nylon fabric, lending a light, breathable feel. The article of footwear <NUM> is characterized by the absence of a rigid heel counter between the control bar <NUM> and the base <NUM> aft of the junction 24A, 24B between the control bar <NUM> and the base <NUM>. The device <NUM> functions at least in some respects as a heel counter in that it helps to retain a wearer's heel in position atop a heel portion of the sole structure, preventing medial or lateral displacement during use. Because the device <NUM> is secured to the flexible covering <NUM>, the device <NUM> together with the flexible covering <NUM> of the upper <NUM> can together be referred to as a footwear upper. In other words, the device <NUM> can be considered a component of a multicomponent footwear upper that also includes the flexible covering <NUM> and other components of the article of footwear. The multicomponent footwear upper may also be referred to as a footwear upper assembly.

Traditionally, slipping a foot into an upper often requires the use of one or both hands to stretch the ankle opening and hold the rear portion during foot insertion, especially in the case of a relatively soft upper and/or an upper that does not have a heel counter secured to the flexible fabric rearward of the ankle opening. The device <NUM> alleviates these issues, and allows the foot <NUM> to enter into a foot-receiving cavity <NUM> formed by the upper <NUM> without the use of hands or other tools. Only the foot <NUM> is used to gain entry. Specifically, using the bottom of the foot <NUM>, a force F is applied to press on the control bar <NUM> as shown in <FIG>, resiliently bending the device at the joints 24A, 24B moving the control bar <NUM> from the unstressed position to the loaded position, which is represented by the control bar in position 14A. The upper <NUM> is attached to the center segment <NUM>, and moves down with the control bar <NUM>. The stored elastic energy due to the bias of the device <NUM> automatically returns the device <NUM> to the unstressed position when the foot <NUM> moves fully into the foot-receiving cavity <NUM>, causing the upper <NUM> to be automatically pulled up over the back of the foot <NUM>. The position of the stretchable flexible covering <NUM> prior to inserting the foot is shown in <FIG>. The flexible covering <NUM> stretches over the back of the heel of the foot <NUM> to the position 42A represented in phantom in <FIG> when the device <NUM> returns to the unstressed position.

To further ease entry of the foot <NUM> into the foot-receiving cavity <NUM> of the upper <NUM>, the center segment <NUM> of the control bar <NUM> has a ramped surface <NUM> that declines toward an inner periphery <NUM> of the center segment <NUM>, as indicted in <FIG> and <FIG>. There is a change in slope of the center segment <NUM> at a transition line <NUM>, between an upper portion <NUM> of the foot contact surface of the control bar <NUM> and the ramped surface <NUM>. The ramped surface <NUM> has a steeper declining slope than the upper portion <NUM>, helping the foot <NUM> to slide down and inward.

With reference to <FIG>, the first side arm <NUM> and the second side arm <NUM> extend at a first acute angle A1 to the common plane P of the base <NUM> when the control bar <NUM> is in the unstressed position. The angle A1 may be measured along a longitudinal axis of each side arm. Although shown with the same angle A1, each of the first side arm <NUM> and the second side arm <NUM> could have a first acute angle with a different numerical value. The first side arm <NUM> and the second side arm <NUM> extend at a second acute angle A2 to the common plane P of the base <NUM> when the control bar <NUM> is depressed so that the device <NUM> is in the position 10A of <FIG>. The angle A2 may be measured along a longitudinal axis of each side arm. The second acute angle A2 is less than the first acute angle A1. Although shown with the same angle A2, each of the first side arm <NUM> and the second side arm <NUM> could have a second acute angle with a different numerical value.

The material of the device <NUM> is selected to provide the ability to elastically deform by elastic bending as described, and store potential energy, such as elastic energy, that returns the device <NUM> to the unstressed position. Example materials include plastics (such as thermoplastics), composites, and nylon. Another example material is a polyether block amide such as PEBAX® available from Arkema, Inc. in King of Prussia, Pennsylvania USA. Another example material is a fiberglass reinforced polyamide. An example fiberglass reinforced polyamide is PISLAN® BZM <NUM><NUM> TL available from Arkema, Inc. in King of Prussia, Pennsylvania USA. Such a fiberglass reinforced polyamide may have a density of <NUM> grams per cubic centimeter under ISO <NUM> test method, an instantaneous hardness of <NUM> on a Shore D scale under ISO <NUM> test method, a tensile modulus of <NUM> MPa under ISO <NUM> test method (with samples conditioned <NUM> days at <NUM> degrees Celsius with <NUM>% relative humidity), and a flexural modulus of <NUM> MPa under ISO <NUM> test method (with samples conditioned <NUM> days at <NUM> degrees Celsius with <NUM>% relative humidity).

Additionally, the relative dimensions and shape of the device at the joints and at the side arms <NUM>, <NUM> contributes to the spring-biased nature of the device <NUM>, and its ability to elastically deform under a desired amount of loading and return to its original unstressed position. The device <NUM> may be configured to elastically bend under a maximum force of 160N. For example, with reference to <FIG>, the first side arm <NUM> and the second side arm <NUM> each have a thickness T1 greater than a width W1 at the respective joint 24A, 24B. The thickness T1 is measured in the fore-aft (longitudinal) direction of the footwear <NUM>. The width W1 is measured in the medial-lateral (transverse) direction of the footwear <NUM>. The greater thickness T1 increases the required force to resiliently bend the device <NUM> to the loaded position.

Additionally, the side arms <NUM> and <NUM> are each twisted outwardly along their respective longitudinal axis 23A, 23B from the joints 24A, 24B at the base to the center segment <NUM>. Stated differently, the inward-facing surfaces <NUM> of the side arms <NUM>, <NUM> flow continually into a slightly upward-facing surface <NUM> as a ridge <NUM> along the side arm <NUM> or <NUM> turns from an upward extending ridge to a partially rearward extending ridge at the back of the center segment <NUM>, as best shown in <FIG>. Similarly, a side surface <NUM> at the arms <NUM> or <NUM> flows into a slightly downward facing surface <NUM> under the ridge <NUM> at the center segment <NUM>, as best shown in <FIG>. This twist in the side arms <NUM>, <NUM> helps encourage the down and back movement of the center segment <NUM> during loading by the foot <NUM>.

The device <NUM> is also configured to widen as it is moved from the unstressed position to the loaded position. This helps ease insertion of the foot <NUM> into a flexible upper <NUM>, as the first side arm <NUM> and the second side arm <NUM> bow apart from one another when the control bar <NUM> is depressed, pulling the upper <NUM> attached to the inward-facing surfaces <NUM> outward. The bowing of the device <NUM> in the loaded position 10A is indicated in the plan view of <FIG>.

While the device <NUM> is thus configured to ease foot entry with its ability to resiliently deform and store elastic energy, it is also configured to limit the amount of deformation to prevent plastic deformation. More specifically, the control bar <NUM> has an extension <NUM> that extends generally toward the base <NUM>. The extension <NUM> is spaced apart from the base <NUM> when the control bar <NUM> is in the unstressed position of <FIG>, and contacts the base <NUM> when the control bar <NUM> is depressed and the device is in the loaded position 10A. In <FIG>, the extension <NUM> is indicated as 70A with the device <NUM> in the loaded position 10A. Contact of the extension <NUM> with the base <NUM> limits further depression of the control bar <NUM>. Alternatively, the base <NUM> could have an extension instead of or in addition to the control bar <NUM>, with the extension on the base extending toward the control bar <NUM>.

In the embodiment of <FIG>, the control bar <NUM> and the base <NUM> have complementary features that interface to limit movement of the device during depression of the control bar <NUM>. For example, the extension <NUM> interfaces with the base <NUM>, limiting depression of the control bar <NUM>, and limiting tilting of the control bar <NUM> toward the lateral or medial side during loading. More specifically, the base <NUM> has a recess <NUM>, and the extension <NUM> protrudes into the recess <NUM> and contacts the base <NUM> when the control bar <NUM> is depressed and the device <NUM> elastically deforms to the loaded position 10A. When in the recess <NUM>, side protrusions <NUM> on either side of the recess <NUM> prevent sideways movement of the extension <NUM>. Because the control bar <NUM> generally comes down along an arc when the joints 24A, 24B bend, the extension <NUM> is positioned so that it will interface with the base <NUM> in the recess <NUM> when it descends along such an arc.

<FIG> show another embodiment of an article of footwear <NUM> with a heel spring device <NUM>. The heel spring device <NUM> has similar function and features as heel spring device <NUM>. Joints 124A, 124B have a greater thickness T2 than the thickness T1 of joints 24A, 24B and thus may provide greater resistance to depression of the control bar <NUM> lessening the need for an extension <NUM> to limit bending. The center segment <NUM> has an aperture <NUM>, and the upper <NUM> has a heel pull tab <NUM> that extends through the aperture <NUM>, further securing the upper <NUM> to the device <NUM>. After insertion through the aperture <NUM>, the heel pull tab <NUM> can wrap around the device <NUM>, could be left hanging loose, or could be stitched or fastened to the upper <NUM> or to itself to secure the upper <NUM> to the device <NUM>.

<FIG> shows another embodiment of an article of footwear <NUM> with a heel spring device <NUM> secured to a sole layer <NUM>. The heel spring device <NUM> has similar function and features as heel spring device <NUM>. An upper is not shown, but would be secured to the sole layer <NUM> and to the device <NUM> as described with respect to device <NUM>.

<FIG> shows another embodiment of an article of footwear <NUM> with a heel spring device <NUM> secured to a sole structure <NUM> that is a midsole, and to an upper <NUM> that has a flexible cover layer with an elastically stretchable material in the heel region. The heel spring device <NUM> has similar function and features as heel spring device <NUM>. The heel spring device <NUM> may include a base <NUM> similar to base <NUM> but that passes through the sole structure <NUM>, or the base arms may terminate on the sole structure <NUM> and be sufficiently secured to the sole structure <NUM> so that the sole structure serves as the base. The device <NUM> is integrated into a fastening system of the upper <NUM>, as the device has loops <NUM> secured to the side arms that serve as anchors for fastener cables <NUM>.

<FIG> show another embodiment of an article of footwear <NUM> that has a heel spring device <NUM> with similar function and features as heel spring device <NUM>. The heel spring device <NUM> is secured to a sole layer <NUM> and to an upper <NUM> that has a flexible covering <NUM> with an elastically stretchable material in the heel region for receiving and covering a foot supported on the sole layer <NUM>. For example, the flexible covering <NUM> may be an elastically stretchable fabric, such as a <NUM>-way stretch nylon fabric. A foam collar <NUM> is secured to the flexible covering <NUM> and defines a front portion of an ankle opening <NUM> in the upper <NUM>. The foam collar is stiffer than the elastically stretchable fabric of the flexible covering <NUM>. The collar <NUM> may include foam padding 435A. The foam padding 435A at a rear portion of the collar may protrude inward into the ankle opening <NUM>. Because the foam is compressible, this enables the size of the opening to be adjustable to different ankle girths.

A center segment of the control bar <NUM> of the device <NUM> has a thinned portion <NUM> where the flexible covering <NUM> of the upper <NUM> is stitched to the device <NUM>. The foam collar <NUM> is also stitched to the device <NUM> at the thinned portion <NUM> as shown in <FIG>. Additional thin extensions <NUM> of the device <NUM> run along the side arms <NUM>, <NUM>, as shown in <FIG>, and are sufficiently thin to allow stitching of the upper <NUM> through the thin extensions <NUM> to the device <NUM>. The stitching <NUM> through the thinned portion <NUM> and through the extensions <NUM> is shown in <FIG>. The upper <NUM> is characterized by the absence of a rigid heel counter. The device <NUM> functions at least in some respects as a heel counter in that it helps to retain a wearer's heel in position atop a heel portion of the sole structure, preventing medial or lateral displacement during use. Similar to device <NUM>, the device <NUM> has a ramped surface <NUM> for easing foot entry.

<FIG> shows another embodiment of an article of footwear <NUM> that has a heel spring device <NUM> with similar function and features as heel spring device <NUM>. The heel spring device <NUM> is secured to a sole layer <NUM> and to an upper <NUM> that has a flexible covering <NUM> with an elastically stretchable material in the heel region for receiving and covering a foot supported on the sole layer <NUM>. The covering <NUM> stretches to position 542A when the foot is inserted. For example, the flexible covering <NUM> may be an elastically stretchable fabric, such as a <NUM>-way stretch nylon fabric. The device <NUM> includes forward extending supports <NUM>. The joints of the device <NUM> are higher than in other embodiments, as they are at the sides of the upper <NUM> above the sole layer <NUM> as shown.

<FIG> shows another embodiment of an article of footwear <NUM> that has a heel spring device <NUM> with similar function and features as heel spring device <NUM>. The heel spring device <NUM> is secured to a sole layer <NUM> and to an upper <NUM> that has a flexible covering with an elastically stretchable material in the heel region for receiving and covering a foot supported on the sole layer <NUM>. For example, the flexible covering may be an elastically stretchable fabric, such as a <NUM>-way stretch nylon fabric. The sole layer <NUM> has molded recesses on its medial and lateral sides in which the base of the device <NUM> and the joints, such as joint 624B partially nest.

<FIG> show another embodiment of an article of footwear <NUM> that includes a heel spring device <NUM> with similar function and features as heel spring device <NUM>. The heel spring device <NUM> is embedded in a flexible covering of an upper <NUM>, and is either secured to a sole layer <NUM> at its base by bonding with adhesive or otherwise, or is simply trapped between the midsole and a strobel or upper materials to reduce the need for adhesive.

<FIG> shows another embodiment of an article of footwear <NUM> that includes a heel spring device <NUM> with similar function and features as heel spring device <NUM>. The heel spring device <NUM> is secured to a sole layer <NUM> at its base, and to a flexible covering of an upper <NUM>. A heel pull tab <NUM> secured to the upper forms a loop through which the device <NUM> passes rearward of an ankle opening, helping to secure the upper <NUM> for movement with the device <NUM>.

<FIG> show another embodiment of an article of footwear <NUM> that includes a heel spring device <NUM> with similar function and features as heel spring device <NUM>. The heel spring device <NUM> is secured to a sole layer (not shown) at its base, and to a flexible covering of an upper <NUM>. The device <NUM> has a control bar <NUM> with side arms <NUM>, <NUM>, and has a base <NUM> that connects the side arms <NUM>, <NUM> and underlies the control bar <NUM>. The base <NUM> extends rearward from a junction 924A, 924B of the control bar <NUM> with the base <NUM> to function as a support. The base <NUM> will underlie a foot-receiving void in an upper to which the heel spring device <NUM> is secured, and may underlie a strobel in the article of footwear <NUM>. The base <NUM> may be secured to a sole layer by bonding with adhesive or otherwise, or may simply be trapped between the sole layer and a strobel or upper materials to reduce the need for adhesive. The device <NUM> widens laterally outward when the control bar <NUM> is depressed, as indicated by the device <NUM> in a loaded position 910A.

<FIG> shows an example diagram of vertical force F in Newtons on the vertical axis versus displacement D in millimeters on the horizontal axis schematically representing the elastic bending and energy-returning behavior of any of the heel spring devices shown and described herein. The displacement D is, for example, the difference between the distances D1 and D2 in <FIG>. A first example representation of the behavior of a heel spring device is shown by a loading curve <NUM> (placement of the force F of <FIG> on the control bar of the device (the vertical component of which is represented in the plots)) followed by an unloading curve <NUM> (behavior when the force F is removed). A second example representation of the behavior of a heel spring device is shown by a loading curve <NUM> followed by an unloading curve <NUM>.

<FIG> show another embodiment of an article of footwear <NUM> that includes a heel spring device <NUM> with similar function and features as heel spring device <NUM>. The heel spring device <NUM> is secured to a sole layer (not shown) at its base, and to a flexible covering of an upper <NUM>. The device <NUM> has a control bar <NUM> with side arms <NUM>, <NUM>, and has a base <NUM> that connects the side arms <NUM>, <NUM> and underlies the control bar <NUM>. The base <NUM> extends rearward from a junction of the control bar <NUM> with the base <NUM> to function as a support. The base <NUM> may underlie a strobel in the article of footwear <NUM>, may be secured to a sole layer by bonding with adhesive or otherwise, or may simply be trapped between the sole layer and a strobel or upper materials to reduce the need for adhesive. The side arms <NUM>, <NUM> of the device <NUM> are similar to the side arms <NUM>, <NUM> of the device <NUM> except that the side arms <NUM>, <NUM> extend from the base <NUM> to the center segment of the control bar <NUM> with a gradually decreasing slope as best shown in <FIG>, while the side arms <NUM>, <NUM> extend from the base <NUM> to the center segment of the control bar <NUM> with a gradually increasing slope as best shown in <FIG>.

<FIG> show another embodiment of an article of footwear <NUM> that includes a heel spring device <NUM> with similar function and features as heel spring device <NUM>. The heel spring device <NUM> is secured to a sole layer (not shown) at its base, and to a flexible covering of an upper <NUM>. The base <NUM> may underlie a strobel in the article of footwear <NUM>, may be secured to a sole layer by bonding with adhesive or otherwise, or may simply be trapped between the sole layer and a strobel or upper materials to reduce the need for adhesive. The device <NUM> has a control bar <NUM> with side arms <NUM>, <NUM>, and has a base <NUM> that connects the side arms <NUM>, <NUM> and underlies the control bar <NUM>. The first side arm <NUM> and the second side arm <NUM> each have a Z shape, as best shown in <FIG> as they first extend rearward, then forward, then rearward again in progressing from the joint 1124A, 1124B to the center segment of the control bar <NUM>. The junctions of the rearward extending portions with the forward extending portions of the side arms <NUM>, <NUM> may serve as additional junctions for resilient bending during loading of the device <NUM> by a downward force on the center segment of the control bar <NUM>. The base <NUM> extends rearward from a junction of the control bar <NUM> with the base <NUM> to function as a support.

<FIG> show another embodiment of a heel spring device <NUM> for an article of footwear. The heel spring device <NUM> has a control bar <NUM> that includes medial and lateral side arms <NUM>, <NUM>. The control <NUM> bar is attachable to a flexible footwear upper. A base <NUM> that extends from and supports the control bar <NUM>. Unlike the other embodiments of heel spring devices disclosed herein, the base <NUM> extends from the center segment of the control bar <NUM>, and the junction is between generally vertical and generally horizontal portions of the base <NUM>.

<FIG> show another embodiment of a heel spring device <NUM> for an article of footwear. The device <NUM> has a control bar <NUM> that includes medial and lateral side arms <NUM>, <NUM> extending from a center segment of the control bar <NUM>. The control <NUM> bar is attachable to a flexible footwear upper. The center segment has an aperture <NUM> for receiving a heel pull tab of a flexible footwear upper or for stitching the control bar <NUM> to a footwear upper. Ends of the side arms <NUM>, <NUM> widen in the longitudinal direction and serve together with a sole layer to which they will be attached as the base and junction 1324A, 1324B of the device <NUM>.

<FIG> shows another embodiment of an article of footwear <NUM> that includes a heel spring device <NUM> with similar function and features as heel spring device <NUM>. The heel spring device <NUM> has a control bar <NUM> secured to a flexible covering of a footwear upper <NUM>. The control bar <NUM> includes medial and lateral side arms (one side arm <NUM> shown). The device <NUM> includes a base (not shown) that connects the side arms and extends through openings <NUM> in the sole layer <NUM> and is secured to or embedded in the sole layer <NUM>. The base may underlie a strobel in the article of footwear <NUM>, may be secured to the sole layer <NUM> by bonding with adhesive or otherwise, or may simply be trapped between the sole layer <NUM> and a strobel or upper materials to reduce the need for adhesive. The sole layer <NUM> thus partly serves as the base and junction with the control arm <NUM>.

<FIG> shows another embodiment of an article of footwear <NUM> that includes a heel spring device <NUM> with similar function and features as heel spring device <NUM>. The heel spring device <NUM> has a control bar <NUM> stitched to a flexible covering of a footwear upper <NUM>. The control bar <NUM> includes medial and lateral side arms (one side arm <NUM> shown). The device <NUM> includes a base (not shown) that connects the side arms and extends through openings in the sole layer <NUM> and is embedded in or otherwise secured to the sole layer <NUM>. The base may underlie a strobel in the article of footwear <NUM>, may be secured to the sole layer <NUM> by bonding with adhesive or otherwise, or may simply be trapped between the sole layer <NUM> and a strobel or upper materials to reduce the need for adhesive. The sole layer <NUM> thus partly serves as a base for the control arm and as a junction <NUM> with the control arm.

<FIG> show another embodiment of a heel spring device <NUM> for an article of footwear. The device <NUM> has a control bar <NUM> that includes medial and lateral side arms <NUM>, <NUM> extending from a center segment <NUM> of the control bar <NUM>. The control <NUM> bar is attachable to a flexible footwear upper. The center segment <NUM> and the side arms <NUM>, <NUM> have apertures <NUM> for stitching the device <NUM> to flexible footwear upper rearward of an ankle opening such as at a rear collar of the ankle opening to prevent a heel tab in that area from folding inward during foot insertion. The device <NUM> has no base. However, the side arms <NUM>, <NUM> may secure near their distal ends to portions of an upper <NUM>, such as slightly stiffer but resiliently flexible portions <NUM> forward of a <NUM>-way stretch fabric <NUM> in the heel region as shown in <FIG>. In this manner, the stiffer portions <NUM> of the upper effectively serve as a base for the device <NUM> and form junctions with the side arms <NUM>, <NUM> to provide a resilient return of the device <NUM> to an unstressed position after a downward force is applied during foot insertion.

<FIG> shows another embodiment of a heel spring device <NUM> for an article of footwear <NUM> shown in <FIG>. The heel spring device <NUM> has similar function and features as heel spring device <NUM>. The device <NUM> has a control bar <NUM> with a center segment <NUM>, a medial side arm <NUM> and a lateral side arm <NUM>. The device <NUM> has a continuous base <NUM> that connects the side arms <NUM>, <NUM> and extends forward from a junction of the control bar <NUM> with the base <NUM>.

As shown in <FIG>, the heel spring device <NUM> is secured to a sole structure <NUM> at its base <NUM>, and to a flexible covering of a footwear upper <NUM> (shown in phantom). The upper <NUM> defines at least a portion of an ankle opening <NUM> and a foot receiving void <NUM>. The base <NUM> underlies the foot-receiving void <NUM>, may underlie a strobel in the article of footwear <NUM>, may be secured to the sole structure <NUM> by bonding with adhesive or otherwise, or may simply be trapped between sole structure <NUM> and a strobel or upper materials to reduce the need for adhesive. The base <NUM> extends both slightly rearward from a junction of the control bar <NUM> with the base <NUM> as well as forward from the junction with the control bar <NUM> to function as a support. The base <NUM> has a forward-extending protrusion <NUM> underlying the foot-receiving void adjacent the medial side <NUM> of the footwear upper, and a rearward extending protrusion <NUM> underlying the foot-receiving void along the lateral side <NUM> of the footwear upper.

<FIG> shows the control bar <NUM> biased to an unstressed position. <FIG> shows the control bar <NUM> elastically bent under an applied force to a loaded position, widening the ankle opening <NUM>. The device <NUM> stores elastic energy that returns the control bar <NUM> to the unstressed position upon removal of the applied load.

<FIG> show an article of footwear <NUM> with a heel spring device <NUM>. The article of footwear <NUM> and the heel spring device <NUM> are alike in many aspects to article of footwear <NUM> and heel spring device <NUM>, and like reference numbers are used to refer to like components. The heel spring device <NUM> is alike in all aspects to heel spring device <NUM> except that the heel spring device <NUM> has a continuous base <NUM> with a main portion <NUM> and a protrusion <NUM> extending downward from the main portion into a recess <NUM> in the foot-facing surface <NUM> of the sole structure <NUM>. The protrusion <NUM> is configured to seat in the recess <NUM>. Walls of the protrusion <NUM> interface with walls of the sole structure <NUM> at the recess <NUM>, lending stability to the base <NUM>. Additionally, the protrusion <NUM> forms a cavity <NUM> in the recess <NUM>, and the cavity may be used to house various footwear components or accessories, such as electronic accessories.

<FIG> shows another embodiment of a heel spring device <NUM> for an article of footwear <NUM> shown in <FIG>. The heel spring device <NUM> has similar function and features as heel spring device <NUM>. The device <NUM> has a control bar <NUM> with a medial side arm <NUM> and a lateral side arm <NUM>. The device <NUM> has a continuous base <NUM> that connects the side arms <NUM>, <NUM> and extends both forward and rearward from a junction of the control bar <NUM> with the base <NUM>.

As shown in <FIG>, the heel spring device <NUM> is secured to the sole structure <NUM> at its base <NUM>, and to the flexible covering of a footwear upper <NUM> (shown in phantom), both of which are described with respect to <FIG>. The base <NUM> underlies the foot-receiving void <NUM>, may underlie a strobel in the article of footwear <NUM>, may be secured to the sole structure <NUM> by bonding with adhesive or otherwise, or may simply be trapped between sole structure <NUM> and a strobel or upper materials to reduce the need for adhesive.

The medial side arm <NUM> and the lateral side arm <NUM> each have at least one slot <NUM> extending therethrough, and in the embodiment shown have multiple slots <NUM>. The slots <NUM> extend through the first side arm <NUM> and lengthwise along a longitudinal axis of the medial side arm <NUM> (i.e., along the length of the side arm <NUM>). Separate slots <NUM> extend through the lateral side arm <NUM> and lengthwise along a longitudinal axis of the lateral side arm <NUM> (i.e., along the length of the side arm <NUM>). The slots <NUM> reduce the thickness of the side arms <NUM>, <NUM>, and accordingly reduce the force required to bend the side arms <NUM>, <NUM>. More specifically, with the slots <NUM>, each side arm is separated into multiple slats <NUM> at the slots. The slats <NUM> function as multiple thinner side arms that bend along their lengths in the region of the slots <NUM>. <FIG> shows the control bar <NUM> biased to an unstressed position. <FIG> shows the control bar <NUM> elastically bent under an applied force to a loaded position, widening the ankle opening <NUM> and tilting the ankle opening downward and rearward in comparison to the unloaded position. A shown in <FIG>, in the loaded position, the side arms <NUM>, <NUM> may be configured so that at least portions of the slots <NUM> close, causing the slats <NUM> to contact one another, increasing stiffness and resistance to further bending. The device <NUM> stores elastic energy that returns the control bar <NUM> to the unstressed position upon removal of the applied load.

The medial side arm <NUM> and the lateral side arm <NUM> each have at least one slot <NUM> extending therethrough, and in the embodiment shown have multiple slots <NUM>. The slots <NUM> extend through the medial side arm <NUM> and are transverse to a longitudinal axis 23A of the medial side arm <NUM> (i.e., transverse to the length of the side arm <NUM>). Separate slots <NUM> extend through the lateral side arm <NUM> and are transverse to a longitudinal axis 23B of the lateral side arm <NUM> (i.e., transverse to the length of the side arm <NUM>). The slots <NUM> reduce the thickness of the side arms <NUM>, <NUM>, and accordingly reduce the force required to bend the side arms <NUM>, <NUM>. More specifically, with the slots <NUM>, each side arm is separated into multiple fingers <NUM> at the slots <NUM>. The fingers <NUM> function to reduce the thickness of the bending portion of the side arms <NUM>, <NUM> to that of the thickness between the end <NUM> of each slot <NUM> and the upper surface <NUM> of each of the side arms <NUM>, <NUM>, rather than the full thickness of the side arm from the upper surface <NUM> to the lower surface <NUM>. The fingers <NUM>, ends <NUM>, and surfaces <NUM>, <NUM> are labelled in <FIG> with respect to lateral side arm <NUM> and apply equally to like features of medial side arm <NUM>. <FIG> shows the control bar <NUM> biased to an unstressed position. <FIG> shows the control bar <NUM> elastically bent under an applied force to a loaded position, widening the ankle opening <NUM> in comparison to the unloaded position. A shown in <FIG>, in the loaded position, the side arms <NUM>, <NUM> may be configured so that at least portions of the slots <NUM> close, causing the fingers <NUM> to contact one another, increasing stiffness and resistance to further bending. The device <NUM> stores elastic energy that returns the control bar <NUM> to the unstressed position upon removal of the applied load.

<FIG> show another embodiment of a heel spring device <NUM> with similar function and features as heel spring device <NUM> and as the heel spring device of <FIG>. In <FIG>, the device <NUM> is shown in an article of footwear <NUM> secured to a sole structure <NUM> and to the flexible covering of a footwear upper <NUM> (shown in phantom), both of which are similar to those described with respect to <FIG>. The heel spring device <NUM> is alike in all aspects to heel spring device <NUM> except that it has a base <NUM> that extends both forward and rearward from the side arms <NUM>, <NUM> of the control bar <NUM>, unlike base <NUM> that extends only rearward.

<FIG> shows an article of footwear <NUM> with another embodiment of a heel spring device <NUM>. The heel spring device <NUM> has similar function and features as heel spring device <NUM>. The device <NUM> has a control bar <NUM> with a medial side arm <NUM>, a lateral side arm <NUM>, and a center segment <NUM> connecting the side arms <NUM>, <NUM> and from which the side arms extend generally downwardly and forwardly. The device <NUM> is secured to a flexible footwear upper <NUM> and to a sole structure <NUM> similarly as described with respect to device <NUM> and article of footwear <NUM>.

A pin <NUM> is disposed substantially horizontally when the footwear <NUM> is in the position of <FIG> resting on the sole structure. The pin <NUM> extends transversely through the sole structure <NUM> and serves as a continuous base and connects to the side arms <NUM>, <NUM> at first and second joints. The pin <NUM> is connected to the medial side arm <NUM> and the lateral side arm <NUM> where they interface with the sole structure <NUM>. The pin <NUM> establishes a pivot axis along the length of the pin <NUM> (transverse to the sole structure <NUM>) about which the control arm <NUM> pivots between the unstressed position and the loaded position. A biasing element such as a torsion spring <NUM> is wrapped around the pin <NUM> with one end fixed to the pin <NUM> and another end fixed to the sole structure <NUM>. For example, the pin <NUM> has a first end <NUM> fixed at the medial side of the sole structure and a second end <NUM> fixed to the pin <NUM>. Pivoting of the control bar <NUM> to the loaded position winds the torsion spring <NUM>, storing potential energy.

The control bar <NUM> is biased to an unstressed position shown in solid. The control bar <NUM> is shown in phantom as 2214A when the device <NUM> is pivoted under an applied force to a loaded position, in which the device is indicated as 2210A. The ankle opening <NUM> widens in the loaded position and may tilt downward and rearward relative to the unloaded position, as the flexible covering <NUM> (also referred to as a flexible cover layer) of the upper <NUM> is secured to the control bar <NUM> and moves downward with the control bar <NUM>. The spring <NUM> stores spring energy that returns the control bar <NUM> to the unstressed position upon removal of the applied load.

<FIG> show an article of footwear <NUM> with another embodiment of a heel spring device <NUM>. The heel spring device <NUM> has similar function and features as heel spring device <NUM>. The device <NUM> has a control bar <NUM> with a medial side arm <NUM> and a lateral side arm (not shown, but a mirror image of medial side arm <NUM>). The device <NUM> has a continuous base <NUM> that connects the side arms and extends both forward and rearward from a junction of the control bar <NUM> with the base <NUM> similar to base <NUM> of <FIG>.

As shown in <FIG>, the heel spring device <NUM> is secured to the sole structure <NUM> at its base <NUM>, and to the flexible covering of a footwear upper <NUM>, both of which are described with respect to <FIG>.

The control bar <NUM> has at least one slot <NUM> that extends continuously from the first side arm <NUM>, across the center segment <NUM>, to the second side arm, and extends through the first side arm <NUM>, through the center segment <NUM>, and through the second side arm (mirror image of slots as shown). In the embodiment shown, there are multiple slots <NUM>. The same slots <NUM> that extend through the first side arm <NUM> and lengthwise along a longitudinal axis of the first side arm <NUM> (i.e., along the length of the side arm <NUM>) also extend through the second side arm and lengthwise along a longitudinal axis of the second side arm (i.e., along the length of the second side arm). The slots <NUM> reduce the thickness of the side arms, and accordingly reduce the force required to bend the side arms. More specifically, with the slots <NUM>, each side arm is separated into multiple slats <NUM> at the slots. The slats <NUM> function as multiple thinner side arms that bend along their lengths in the region of the slots <NUM>.

<FIG> shows the control bar <NUM> biased to an unstressed position. <FIG> shows the control bar <NUM> elastically bent under an applied force to a loaded position, widening the ankle opening <NUM> and tilting the ankle opening downward and rearward in comparison to the unloaded position. A shown in <FIG>, in the loaded position, the side arms <NUM> (and second side arm not shown) may be configured so that at least portions of the slots <NUM> close, causing the slats <NUM> to contact one another, increasing stiffness. However, the slats <NUM> can slide against one another when they come into contact due to the slots <NUM> closing. The sliding enables further bending to continue at a reduced stiffness in comparison to a control bar like control bar <NUM> but without slots. <FIG> shows a slight stagger at the rear of the stacked slats <NUM>, indicating that they have slid relative to one another with the slots closed. The device <NUM> stores elastic energy that returns the control bar <NUM> to the unstressed position upon removal of the applied load.

<FIG> shows an article of footwear <NUM> with another embodiment of a heel spring device <NUM>. The heel spring device <NUM> has similar function and features as heel spring device <NUM>. The device <NUM> has a control bar <NUM> with a medial side arm <NUM> and a lateral side arm <NUM>, and a center segment <NUM> connecting the side arms <NUM>, <NUM> and from which the side arms extend generally downwardly and forwardly. The device <NUM> has a continuous base <NUM> that connects the side arms <NUM>, <NUM> at first and second joints 24A, 24B, described with respect to <FIG>. The device <NUM> is secured to a flexible footwear upper <NUM> and to a sole structure <NUM> similarly as described with respect to device <NUM>.

The center segment <NUM> has an aperture <NUM>, and the upper <NUM> has a heel pull tab <NUM> that extends through the aperture <NUM>, further securing the upper <NUM> to the device <NUM>. The center segment <NUM> also has an extension <NUM> that extends downward from the center segment <NUM> and may limit bending of the device <NUM> by interference with the base <NUM>, similarly as described with respect to extension <NUM>. The extension <NUM> has a fastener opening <NUM> that receives a stud (not shown) that can be used to secure the heel pull tab <NUM> to the extension <NUM> with a fastener such as a stud, a snap, or a button. Alternatively, or in addition, the heel pull tab <NUM> may be secured to a mounting surface <NUM> of the extension <NUM> with adhesive or otherwise.

<FIG> shows an article of footwear <NUM> with another embodiment of a heel spring device <NUM>. The heel spring device <NUM> has a rear control bar <NUM> with a medial side arm <NUM> secured at a medial side of the footwear and a lateral side arm (not shown) that is a mirror image of the medial side arm <NUM> but is secured at the lateral side of the footwear <NUM>. The rear control bar <NUM> also has a center segment <NUM> connecting the medial and lateral side arms and from which the side arms extend generally downwardly and forwardly. The device has a front bar <NUM> that also has a medial side arm, a lateral side arm, and a center segment <NUM> connecting the medial and lateral side arms. A flexible footwear upper <NUM> is secured to the center segment <NUM> of the front bar <NUM>, to the center segment <NUM> of the rear control bar <NUM>, as well as to the medial and lateral side arms of the rear control bar <NUM> and the front bar <NUM>. The relative positions of the center segments <NUM>, <NUM> thus determine the fore-aft expanse of the ankle opening <NUM> formed by the upper <NUM>.

The bars <NUM> and <NUM> may be anchored at their ends to the sole structure <NUM>. The bars <NUM>, <NUM> are positioned to cross one another at both the medial and lateral sides, and are pivotably secured to one another at a connection <NUM> (one shown) at both the lateral and medial sides where they cross. The connection <NUM> may be a pin joint. A torsion spring <NUM> may be operatively secured at the connection. Upper portions of the bars <NUM>, <NUM> may be elastically bendable so that the center segments <NUM> and <NUM> can move apart from one another when a force is applied on the center segment <NUM>, such as the force of a foot gaining entry to the upper <NUM>. Positions of the center segments <NUM>, <NUM> under loading are shown in phantom as 2416A, 2516A. The device <NUM> stores potential energy, such as elastic energy and/or spring energy, that returns the rear control bar <NUM> to the unstressed position upon removal of the applied force (i.e., after a foot slides into the foot-receiving cavity of the upper <NUM>).

<FIG> shows an article of footwear <NUM> with another embodiment of a heel spring device <NUM>. The heel spring device <NUM> has similar function and features as heel spring device <NUM>. The device <NUM> has a control bar <NUM> with a series of slats <NUM>, and multiple slots <NUM>, best shown in <FIG>. Each slat <NUM> has a center segment <NUM>, a medial side arm <NUM> (best shown in <FIG>) and a lateral side arm <NUM>. The lateral side arm <NUM> and the medial side arm <NUM> may be configured as mirror images of each other in one or more embodiments. The device <NUM> has a continuous base <NUM> that underlies the control bar <NUM>, and that connects the side arms <NUM>, <NUM> and extends both forward and rearward from a junction of the control bar <NUM> with the base <NUM> similar to base <NUM> of <FIG>. As is evident from <FIG> and <FIG>, the device <NUM> has a concave inner surface <NUM> with a concavity in both the medial-lateral and vertical directions.

The article of footwear <NUM> includes a sole structure <NUM> and a footwear upper <NUM> with a flexible covering which is described with respect to <FIG>. The heel spring device <NUM> is secured to the flexible covering of the footwear upper <NUM> via a strap <NUM> that has a pocket <NUM>, as described with respect to <FIG>.

The heel spring device <NUM> is also secured to the sole structure <NUM> at the base <NUM> of the heel spring device <NUM>, as shown in <FIG>. As shown in <FIG>, the outer surface of the base <NUM> of the device <NUM> has a peripheral recess 2622A extending from a lower edge 2622B of the base <NUM>. The peripheral recess 2622A is shown at the lateral side of the base <NUM> in <FIG>, <FIG> and extends around to the medial side of the base <NUM> in a mirror image of the lateral side. The peripheral recess 2622A is shaped and dimensioned to receive a flange 2632A of the sole structure <NUM>, shown in <FIG>. The flange 2632A may be adhered or heat bonded to the base <NUM> in the peripheral recess 2622A. The sole structure <NUM> thus provides lateral support to the base <NUM>.

The control bar <NUM> is biased to an unloaded position shown in <FIG>, and elastically bends under an applied force F to a loaded position shown in <FIG>, in which each center segment <NUM> is closer to the base <NUM> than in the unloaded position, storing potential energy that returns the control bar <NUM> to the unloaded position upon removal of the applied force F. The control bar <NUM> and the base <NUM> are configured as a full elliptical leaf spring. The device <NUM> may be a resiliently bendable nylon or another resiliently bendable material. The center segment <NUM> is spaced apart from the base <NUM>, and the device <NUM> is characterized by the absence of a rigid heel counter between the center segment <NUM> and the base <NUM> aft of a junction 2624A of the medial side arm <NUM> and the base <NUM> (represented in <FIG> and a mirror image of junction 2624B) and aft of a junction 2624B between the lateral side arm <NUM> and the base <NUM>. The device <NUM> functions at least in some respects as a heel counter in that it helps to retain a wearer's heel in position atop a heel portion of the sole structure, preventing medial or lateral displacement during use.

The slots <NUM> reduce the amount of material between an uppermost one 2681B of the slats and a lowermost one 2681A of the slats at the side arms as shown in <FIG>, and accordingly reduce the force required to bend the side arms. More specifically, with the slots <NUM>, the slats <NUM> function as multiple thinner side arms that bend along their lengths in the region of the slots <NUM>. A lowermost one 2681A of the slats <NUM> closest to the base <NUM> at the center segment <NUM> is shorter from its medial end 2682A to its lateral end 2683A than is an uppermost one 2681B of the slats <NUM> from its medial end 2682B to its lateral end 2683B, where the uppermost slat 2681B is furthest from the base <NUM>. The medial ends 2682A, 2682B are indicated in <FIG> and are a mirror image of lateral ends 2683A, 2683B shown in <FIG>.

In one or more embodiments, the lowermost one of the slats 2681A is thinner than the uppermost one of the slats 2681B at any location along their lengths between the medial ends and the lateral ends, as is evident by comparing thickness T3 of the lowermost slat 2681A to thickness T4 of the uppermost slat 2681B in the exemplary embodiment of <FIG>. Stated differently, while the thickness of slat 2681A may vary from its medial end to its lateral end, and the thickness of slat 2681B may vary from its medial end to its lateral end, at any given position between the medial end and the lateral end of slat 2681A, the thickness of slat 2681A will be less than the thickness of slat 2681B along a line perpendicular to the longitudinal axis of slat 2681A.

The slats <NUM> are spaced apart from one another by the slots <NUM> when the control bar <NUM> is in the unloaded position of <FIG>. The slots <NUM> close between the slats <NUM> at least at some portion of the slots <NUM> so that adjacent center segments <NUM> contact one another in the loaded position of <FIG>. In the embodiment shown, the slots <NUM> close at the center segments <NUM> in the loaded position, but may remain open at the side arms <NUM>, <NUM>. The slots <NUM> are parallel with one another, and exterior sides <NUM> of the slats <NUM> are flush with one another in the unloaded position shown in <FIG>. The slots <NUM> enable the control bar <NUM> to bend with less resistance (i.e., lower stiffness) than if the control bar <NUM> were of the same overall thickness as the multiple slats <NUM> from the uppermost slat 2681B to the lowermost slat 2681A. The slats <NUM> can slide against (but not past) one another when they come into contact due to the slots <NUM> closing, in a typical embodiment corresponding to <FIG>. The sliding enables further bending to continue at a reduced stiffness in comparison to a control bar configured in the manner of control bar <NUM> but without slots. <FIG> shows a slight stagger at the rear of the stacked slats <NUM>, indicating that they have slid relative to one another with the slots <NUM> closed.

<FIG> shows the control bar <NUM> biased to an unstressed (i.e., unloaded) position. <FIG> shows the control bar <NUM> elastically bent under an applied force F (such as a force from a foot sliding into the article of footwear) to a loaded position, which will widen the ankle opening <NUM> of the upper <NUM> of <FIG> in comparison to the unloaded position as the upper <NUM> moves with the control bar <NUM> in the heel region. A heel region of the upper <NUM> rearward of the ankle opening <NUM> moves with the center section <NUM> of the control bar closer to the base <NUM> when the force F is applied, causing the ankle opening <NUM> to enlarge or at least change the position of the ankle opening such that it may tilt downward and rearward relative to the unloaded position and is accessible for foot entry in a downward and forward direction from the rear, rather than only downward, as best shown by comparing the position of the ankle opening <NUM> in <FIG> to the position of the ankle opening <NUM> in <FIG>.

More specifically, the upper <NUM> is connected to the heel spring device <NUM> via an extension <NUM> and a strap that has a pocket <NUM>. With reference to <FIG>, the lowermost slat 2681A has an extension <NUM> extending from a lower edge <NUM> of the center segment <NUM>. The extension <NUM> extends at least partially downward from the center segment <NUM>, at least partially toward the base <NUM>. As shown in <FIG>, the extension <NUM> extends downward and rearward when the control arm <NUM> is in the unloaded position. In the loaded position of <FIG>, the extension points straighter downward than in the unloaded position. Additionally, the control bar <NUM> and the extension <NUM> are configured to move clear of the base <NUM> such that the extension is rearward of the base <NUM> when the control arm <NUM> is in the loaded position. No recess is needed in the base <NUM> in such an embodiment.

With reference to <FIG>, <FIG>, a strap <NUM> has a proximal end 2633A sewn, integrally formed with, or otherwise connected to the upper <NUM> near the ankle opening <NUM> at the rear of the upper <NUM>. The strap <NUM> has a pocket <NUM> at a distal end 2633B. The pocket <NUM> may be formed, for example, by folding the strap <NUM> over on itself at the distal end 2633B and stitching the folded portion to the remainder of the strap <NUM>. The strap <NUM> extends downward from the upper <NUM>. The strap <NUM> is placed over and rearward of the control bar <NUM>, and the extension <NUM> is then disposed in the pocket <NUM> with the strap <NUM> overlaying the center segment <NUM>. The extension <NUM> and strap <NUM> are thus used to operatively connect the upper <NUM> to the control bar <NUM> so that the portion of the upper <NUM> rearward of the ankle opening <NUM> will move downward with the control bar <NUM> to the loaded position, easing foot entry into the foot-receiving cavity of the upper <NUM> through the ankle opening <NUM>, and then move back upward with the control bar to the unloaded position when the force F is removed, placing the upper <NUM> around the back of a foot that has been inserted into the foot-receiving cavity.

<FIG> shows an article of footwear <NUM> with another embodiment of a heel spring device <NUM>. Like reference numbers are used to refer to components identical to those described with respect to article of footwear <NUM> and heel spring device <NUM>. The heel spring device <NUM> has similar function and features as heel spring device <NUM>. The device <NUM> has a control bar <NUM> with a series of slats <NUM>, and multiple slots <NUM> best shown in <FIG>. Each slat <NUM> has a center segment <NUM>, a medial side arm <NUM> (best shown in <FIG>) and a lateral side arm <NUM>, best shown in <FIG>. The lateral side arm <NUM> and the medial side arm <NUM> are mirror images of each other. The device <NUM> has the continuous base <NUM>, as described with respect to <FIG> and <FIG>, that underlies the control bar <NUM>, and that connects the side arms and extends rearward from a junction of the control bar <NUM> with the base <NUM>. As is evident from <FIG> and <FIG>, the device <NUM> has a concave inner surface <NUM> with a concavity in both the medial-lateral and vertical directions.

The slots <NUM> reduce the amount of material between an uppermost one 2781B of the slats and a lowermost one 2781A of the slats at the side arms, and accordingly reduce the amount of force required to bend the side arms via the force F applied to the center segment <NUM>. More specifically, due to the slots <NUM>, the slats <NUM> function as multiple thinner side arms that bend along their lengths in the region of the slots <NUM>. As shown in <FIG> and <FIG>, a lowermost 2781A one of the slats <NUM> closest to the base <NUM> at the center segment <NUM> is shorter from its medial end 2782A to its lateral end 2783A than is an uppermost one 2781B of the slats <NUM> from its medial end 2782B to its lateral end 2783B, where the uppermost slat 2781B is furthest from the base <NUM>. The medial ends 2782A, 2782B are indicated in <FIG> and are a mirror image of lateral ends 2783A, 2783B.

At any point along the lowermost one of the slats 2781A, the lowermost one of the slats 2781A is thinner than any one of the other slats at a corresponding point (e.g., at a point directly aligned above the point along the lowermost one of the slats), as best shown in <FIG>. The thickness of a slat is measured along its longitudinal axis. While the thickness of slat 2781A may vary along its longitudinal axis from its medial end to its lateral end, and the thickness of slat 2781B may vary along its longitudinal axis from its medial end to its lateral end, at any given point between the medial end and the lateral end of slat 2781A, the thickness of slat 2781A will be less than the thickness of slat 2781B at a point directly aligned above the point along slat 2781A.

The slats <NUM> are spaced apart from one another by the slots <NUM> when the control bar <NUM> is in the unloaded position of <FIG>. The heel spring device <NUM> includes a resilient insert <NUM> that at least partially fills the slots <NUM>. The resilient insert <NUM> may comprise a resiliently compressible material, such as at least one of rubber or thermoplastic polyurethane, and may be a foam, but is not limited to these materials. In the embodiment shown, the resilient insert <NUM> is a thermoplastic polyurethane foam that provides compressive stiffness and elastic resiliency. As best shown in <FIG>, the resilient insert <NUM> includes a sleeve <NUM> with spaced protrusions <NUM> extending outward on an outer surface <NUM> of the sleeve <NUM>. As best shown in <FIG>, the sleeve <NUM> is configured to extend along an inner side of the slats <NUM> from the uppermost one 2781B of the slats <NUM> to a lower periphery of the base <NUM>. An outer perimeter of the sleeve <NUM> is coincident with an outer perimeter of the slats <NUM> and base <NUM>.

The spaced protrusions <NUM> extend from the sleeve <NUM> into the slots <NUM> between the slats <NUM>. The spaced protrusions <NUM> are shaped and dimensioned to completely fill the slots <NUM> when the device <NUM> is in the unloaded position of <FIG>. In other embodiments, the spaced protrusions <NUM> could be narrower than the slots <NUM>. The spaced protrusions <NUM> may be flush with the outer surfaces of the slats <NUM>, or may extend outward beyond the outer surfaces of the slats <NUM>. The slats <NUM> and base <NUM> may be referred to as a cage which supports the insert <NUM>.

The slots <NUM> partially close between the slats <NUM> when a downward force F is applied to the control bar <NUM>, moving the control bar <NUM> to the loaded position of <FIG> so that the adjacent center segments <NUM> move closer to one another and the protrusions <NUM> are partially compressed between the slats <NUM>. The sleeve <NUM> also compresses as it moves downward with the control bar <NUM>. Because the sleeve <NUM> and/or the slats <NUM> are operatively secured to the heel portion of the flexible covering of the upper <NUM> rearward of the ankle opening <NUM>, the upper <NUM> moves downward with the sleeve <NUM> and control bar <NUM> to the loaded position. The amount of force required to move the device <NUM> from the unloaded position to the loaded position is thus dependent on both the bending stiffness of the control arm <NUM> and the compressive stiffness of the resilient insert <NUM> in the slots <NUM>. The compressive stiffness of the insert <NUM> is less than the bending stiffness of the slats <NUM>, and therefore enables the control bar <NUM> to bend with a lower force F than if the control bar <NUM> were of the same overall thickness as the multiple slats <NUM> from the uppermost slat 2781B to the lowermost slat 2781A (i.e., if the control bar <NUM> had no slats).

The article of footwear <NUM> includes the sole structure <NUM> and the footwear upper <NUM> with a flexible covering. The heel spring device <NUM> is secured to the flexible covering of the footwear upper <NUM> with adhesive, stitching, thermal bonding, or otherwise so that a rear portion of the upper <NUM> rearward of the ankle opening <NUM> moves with the heel spring device <NUM>. The heel spring device <NUM> is also secured to the sole structure <NUM> at its base <NUM> by the flange 2632A of the sole structure <NUM> secured in the peripheral recess 2622A.

The control bar <NUM> is biased to an unloaded position shown in <FIG>, and elastically bends under an applied force F to a loaded position shown in <FIG>. In the loaded position, each center segment <NUM> is closer to the base <NUM> than in the unloaded position due to the arms <NUM>, <NUM> bending and storing potential energy that returns the control bar <NUM> to the unloaded position upon removal of the applied force F. The control bar <NUM> and the base <NUM> are configured as a full elliptical leaf spring. The slats <NUM> and base <NUM> may be nylon or another resiliently bendable material.

<FIG> shows the control bar <NUM> biased to an unstressed (i.e., unloaded) position. <FIG> shows the control bar <NUM> elastically bent under an applied force F (such as a force of a foot sliding into the article of footwear) to a loaded position, which will widen the ankle opening <NUM> of the upper <NUM> of <FIG> in comparison to the unloaded position, as the upper <NUM> moves with the control bar <NUM> in the heel region. A heel region of the upper <NUM> rearward of the ankle opening <NUM> moves with the center section <NUM> of the slats <NUM> closer to the base <NUM> when the force F is applied, causing the ankle opening <NUM> to enlarge or at least change position by lowering the upper <NUM> rearward of the ankle opening <NUM> such that the ankle opening <NUM> may tilt downward and rearward relative to the unloaded position and is accessible for foot entry of a foot moving in a downward and forward direction from the rear.

The slats <NUM> and base <NUM> may be injection molded. Once molded, the slats <NUM> and base <NUM> are a single, unitary component. The material of the foam insert <NUM> may then be injected into a mold cavity containing the molded slats <NUM> and base <NUM>. <FIG> shows apertures <NUM> (only some of which are numbered) where pins hold the slats <NUM> and base <NUM> against a surface of the mold while the material of the insert <NUM> is injected. The insert <NUM> is molded around ribs <NUM> of the base <NUM> near the junctions of the slats <NUM> with the base <NUM>, as indicated by slots <NUM> in the insert <NUM> in <FIG>.

<FIG> shows an article of footwear 2712A with another embodiment of a heel spring device 2710A. The heel spring device 2710A is alike in all aspects as heel spring device <NUM>, except that the insert <NUM> has protrusions 2792A that are configured as bellows that extend outward and fill slots between the slats <NUM> between the slats <NUM> from an inner side of the slats <NUM>. The slats <NUM> and base <NUM> may be formed of a semi-rigid or rigid thermoplastic polyurethane, while the insert <NUM> with protrusions 2792A may be formed of a softer thermoplastic polyurethane relative to the slats <NUM> and base <NUM>.

<FIG> shows an article of footwear <NUM> with another embodiment of a heel spring device <NUM>. Like reference numbers are used to refer to components identical to those described with respect to article of footwear <NUM> and heel spring device <NUM>. The heel spring device <NUM> has a similar function as heel spring device <NUM>, but is comprised of an elastic corrugated body <NUM> including a center segment <NUM>, a medial side arm <NUM> (best shown in <FIG>) extending downwardly and forwardly from the center segment <NUM>, and a lateral side arm <NUM> (best shown in <FIG>) extending downwardly and forwardly from the center segment <NUM>. The corrugated body <NUM> includes alternating ridges <NUM> and grooves <NUM> that extend lengthwise along the medial side arm <NUM>, the center segment <NUM> and the lateral side arm <NUM>. As is evident from <FIG> and <FIG>, the device <NUM> has a concavity at an inner surface in both the medial-lateral and vertical directions.

The corrugated body <NUM> is biased to an unloaded position shown in <FIG>, <FIG> and <FIG>. The corrugated body <NUM> compresses under an applied force F to a loaded position shown in <FIG>. In the loaded position, the corrugated body <NUM> compresses (e.g., by folding) so that adjacent ones of the alternating ridges <NUM> are closer to one another than in the unloaded position, particularly at the center segment <NUM>, storing elastic energy that returns the corrugated body <NUM> to the unloaded position upon removal of the applied force F. The upper <NUM> moves with the center segment <NUM> such that the ankle opening <NUM> may tilt downward and rearward relative to the unloaded position when the heel spring device <NUM> is in the loaded position.

As indicated in <FIG>, a first set of the ridges 2881A and grooves 2880A extend from the medial side arm <NUM> to the lateral side arm <NUM>, and a second set of the ridges 2881B and grooves 2880B extend only along the center segment <NUM>. The first and second sets are configured so that the ridges and grooves can follow the contours of the upper <NUM>, extending along the entire portion of the upper <NUM> rearward of the ankle opening <NUM>, while still allowing some of the grooves and ridges (i.e., the first set) to extend downwardly and forwardly.

Referring to <FIG>, the device <NUM> may include an upper flange <NUM> extending along an upper edge <NUM> of the corrugated body <NUM> at the center segment <NUM>, and further comprises a lower flange <NUM> extending along a lower edge <NUM> of the corrugated body <NUM> at the medial arm <NUM>, the center segment <NUM>, and the lateral arm <NUM>.

The lower flange <NUM> is also referred to as a base. The sole structure <NUM> is secured to the lower flange <NUM> by adhesive, thermal bonding, or otherwise, so that the sole structure <NUM> generally underlies the upper <NUM> and the heel spring device <NUM> as shown in <FIG>. As best shown in <FIG>, the outer surface of the base <NUM> has a peripheral recess 2822A extending from a lower edge 2822B of the base <NUM>. The sole structure <NUM> has a flange 2632A configured to be seated in the peripheral recess 2822A. The flange 2632A of the sole structure <NUM> provides lateral support to the heel spring device <NUM>.

The upper flange <NUM> is stitched to the upper <NUM> rearward of the ankle opening <NUM> as shown by stitches <NUM> in <FIG>. The upper flange <NUM> may alternatively be adhered or thermally bonded to the upper <NUM>. The connection of the heel spring device <NUM> to the upper <NUM> via the upper flange <NUM> enables the upper <NUM> to move with the heel spring device <NUM> between the loaded and unloaded positions.

The ridges <NUM> and grooves <NUM> of the corrugated body <NUM> may also be referred to as bellows. The ridges <NUM> are pleats of the bellows and the grooves <NUM> are folds of the bellows. The device <NUM> is a one-piece, unitary component that includes the corrugated body <NUM> and the flanges <NUM>, <NUM>. The device <NUM> may be injection molded of an elastically deformable material, such as at least one of rubber or thermoplastic polyurethane, and may be a resilient foam (e.g., a polymer foam material, etc.), but is not limited to these materials.

<FIG> shows another embodiment of a heel spring device <NUM> within the scope of the present teachings. The heel spring device <NUM> has the spaced slats <NUM> and a base <NUM> as described with respect to the heel spring device <NUM>, and is biased to the unloaded position shown in <FIG>, but elastically bends to a loaded position (not shown) in response to an applied load, which helps to open an ankle opening of an upper to ease foot entry as described with respect to heel spring device <NUM>. The heel spring device <NUM> includes discrete resilient inserts <NUM> disposed in the slots <NUM> but only along a portion of the center segments <NUM> (e.g., not in the slots of the side arms). A strap <NUM> is adhered or otherwise connected to the inserts <NUM> and to the slats <NUM> to retain the inserts <NUM> in position within the slots <NUM>. Alternatively, the strap <NUM> may be an integral portion of the resilient inserts <NUM> such that the resilient inserts <NUM> are integrated as a unitary component.

<FIG> shows another embodiment of a heel spring device <NUM>. The heel spring device <NUM> has the spaced slats <NUM> and the base <NUM> as described with respect to the heel spring device <NUM>, and is biased to the unloaded position shown in <FIG>, but elastically bends to a loaded position (not shown) which helps to open an ankle opening of an upper to ease foot entry as described with respect to heel spring device <NUM>. The heel spring device <NUM> has a pair of intermediate slats <NUM> arranged as an elliptical spring between the base <NUM> and a middle one of the slats <NUM> and connected to the base <NUM> and the middle slat <NUM>, respectively. The heel spring device <NUM> also has a pair of intermediate slats <NUM> arranged as an elliptical spring between the uppermost slat and the middle one of the slats <NUM>, and connected to the uppermost slat and the middle slat, respectively. The intermediate slats <NUM>, <NUM> provide additional resistance to bending and stored elastic energy to return the heel spring device <NUM> to the unloaded position upon removal of the applied load. The arrangement of slats <NUM> and intermediate slats <NUM>, <NUM> may be referred to as a lattice.

<FIG> shows an article of footwear <NUM> with another embodiment of a heel spring device <NUM>. Like reference numbers are used to refer to components identical to those described with respect to article of footwear <NUM> and heel spring device <NUM>. The heel spring device <NUM> has a similar function as heel spring device <NUM>, but is comprised of a fluid-filled bladder <NUM> including a center segment <NUM>, a medial side arm <NUM> (shown in <FIG>) extending downwardly and forwardly from the center segment <NUM>, and a lateral side arm <NUM> extending downwardly and forwardly from the center segment <NUM>. The sole structure <NUM> is secured to a lower flange <NUM> of the bladder element <NUM> by adhesive, thermal bonding, or otherwise, so that the sole structure <NUM> generally underlies the upper <NUM> and the heel spring device <NUM> as shown in <FIG>.

Application of a downward force F on the center segment <NUM> moves the bladder element <NUM> from an unloaded position (<FIG>) to a loaded position (<FIG>). The unloaded position is also referred to as an expanded position, and the loaded position is also referred to as a collapsed or compressed position. The center segment <NUM> may be referred to as a control bar.

The bladder element <NUM> may be thermoformed from a first polymeric sheet <NUM> and a second polymeric sheet <NUM> (best shown in <FIG> and also referred to as an inner and an outer sheet, or an inner and an outer layer, respectively). Alternatively, the bladder element <NUM> may be blow-molded from a pre-form polymeric material. The bladder element <NUM> can be formed from any of various polymeric materials that retain a fluid at a predetermined pressure, including a fluid that is a gas, such as air, nitrogen, or another gas. As used herein, a "fluid" includes a gas, including air, an inert gas such as nitrogen, or another gas. Accordingly, "fluid-filled" includes "gas-filled".

For example, the bladder element <NUM> can be a TPU material, a urethane, polyurethane, polyester, polyester polyurethane, and/or polyether polyurethane. Moreover, in one embodiment, the bladder element <NUM> can be formed from sheets having layers of different materials. The sheets <NUM>, <NUM> may be laminate membranes formed from thin films having one or more first layers that comprise thermoplastic polyurethane layers and that alternate with one or more second layers, also referred to herein as barrier layers, gas barrier polymers, or gas barrier layers. The second layers may comprise a copolymer of ethylene and vinyl alcohol (EVOH) that is impermeable to the pressurized fluid contained therein as disclosed in <CIT> The first layer may be arranged to form an outer surface of the polymeric sheet. That is, the outermost first layer may be the outer surface of the bladder element <NUM>. The bladder element <NUM> may also be formed from a material that includes alternating layers of thermoplastic polyurethane and ethylene-vinyl alcohol copolymer, as disclosed in <CIT> and <CIT> Alternatively, the layers may include ethylene-vinyl alcohol copolymer, thermoplastic polyurethane, and a regrind material of the ethylene-vinyl alcohol copolymer and thermoplastic polyurethane. The sheets <NUM>, <NUM> may have alternating layers of thermoplastic urethane (TPU) and a gas barrier material. In the embodiment shown, the sheets <NUM>, <NUM> are transparent.

The sheets <NUM>, <NUM> are bonded to one another at a periphery of the bladder element <NUM>, such as at an upper flange <NUM> and the lower flange <NUM>, also referred to as a base. The lower flange <NUM> is continuous and is connected to and supports the medial side arm <NUM>, the center segment <NUM>, and the lateral side arm <NUM>. The sheets <NUM>, <NUM> are also bonded to one another at various intermediate bond locations <NUM>, referred to as webbing. The upper flange <NUM> is thermally bonded, adhered, or otherwise secured to the upper <NUM> rearward of the ankle opening <NUM> as shown in <FIG>. The upper <NUM> may also be secured to the inner surface of the first polymeric sheet <NUM> between the upper and lower flanges <NUM>, <NUM>. The connection of the heel spring device <NUM> to the upper <NUM> via the upper flange <NUM> enables the upper <NUM> to move with the heel spring device <NUM> between the loaded and unloaded positions. More specifically, the upper <NUM> moves with the center segment <NUM> such that the ankle opening <NUM> may tilt downward and rearward relative to the unloaded position when the heel spring device <NUM> is in the loaded position, enabling hands-free foot entry.

The bonded sheets <NUM>, <NUM> form various fluid-filled interior cavities 3181A, 3181B, 3181C, 3183A, and 3183B which are fluid-tight, and may be pressurized or unpressurized. In the embodiment shown, the fluid-filled interior cavities 3181A, 3181B, 3181C, 3183A, and 3183B are at the ambient pressure of the environment in which the fluid-filled cavities were sealed. Alternatively, the fluid-filled interior cavities 3181A, 3181B, 3181C, 3183A, and 3183B could be pressurized by fluid introduced into the cavities through one or more inflation ports (not shown) that are then sealed.

In the embodiment shown, each of the fluid-filled interior cavities 3181A, 3181B, and 3181C is generally tubular, and extends lengthwise along the medial side arm <NUM>, the center segment <NUM>, and the lateral side arm <NUM>. In some embodiments, the cavities 3181A, 3181B, 3181C only extend along the center segment <NUM>. The cavities 3181A, 3181B, 3181C may be referred to as elongated cavities or tubular cavities. Alternatively, fluid-filled cavities of other shapes may extend along the center segment <NUM>, and may also extend along either or both of the medial side arm and the lateral side arm. For example, multiple discrete cavities shaped as tubes that are shorter than the cavities 3181A, 3181B, 3181C, or having other shapes, may extend along the center segment <NUM> and may be fluidly-interconnected to one another by channels formed by the sheets.

The tubular cavities 3181A, 3181B, and 3181C are connected with and in fluid communication with the fluid-filled interior cavities 3183A, 3183B, which may be referred to as a medial reservoir 3183A and a lateral reservoir 3183B. In this manner, the tubular cavities 3181A, 3181B, and 3181C are indirectly in fluid communication with one another via the reservoirs 3183A, 3183B. In some embodiments, channels extending directly between adjacent ones of the tubular cavities 3181A, 3181B, and 3181C may also be provided such that the tubular cavities 3181A, 3181B, 3181C are in direct fluid communication with one another. In some embodiments, only one of the reservoirs 3183A, 3183B is provided, or no reservoirs are provided, and the tubular cavities 3181A, 3181B, and 3181C simply end on the side arm that does not have a reservoir. In still other embodiments, each of the tubular cavities may have its own separate reservoir on either or both of the side arms. The reservoirs 3183A, 3183B are formed by the first and second polymeric sheets <NUM> and <NUM> at medial and lateral extremities of the tubular cavities 3181A, 3181B, and 3181C, respectively. As is apparent from <FIG>, the device <NUM> has a concavity at the inner surface of the first polymeric sheet in both the medial-lateral and vertical directions.

The formed sheets <NUM>, <NUM> with interior cavities 3181A, 3181B, 3181C, 3183A, 3183B bias the heel spring device <NUM> to the unloaded position shown in <FIG>. The heel spring device <NUM> compresses under the applied force F to the loaded position shown in <FIG>, storing elastic energy. For example, the applied force F may be the force of a foot as it is being inserted into the ankle opening <NUM> of the article of footwear <NUM>. In the loaded position, the bladder element <NUM> is resiliently deformed as the force F is applied generally over the center segment <NUM> of the tubular cavities 3181A, 3181B, and 3181C such that the top of the center segment <NUM> is closer to the flange <NUM> in the loaded position than in the unloaded position.

Some of the fluid within the fluid-filled interior cavities 3181A, 3181B, and 3181C may be displaced to the reservoirs 3183A, 3183B as the tubular cavities 3181A, 3181B, and 3181C are compressed, causing the reservoirs to expand and bulge outward, as represented in <FIG> at reservoir 3183A. The resiliently deformed bladder element <NUM> returns to the unloaded position of <FIG> as the displaced fluid returns from the reservoirs 3183A, 3183B to the tubular cavities 3181A, 3181B, and 3181C upon removal of the applied force F, expanding the tubular cavities 3181A, 3181B, 3181C to their original shapes and reducing the sizes of the reservoirs 3183A, 3183B to their original shapes.

<FIG> shows another embodiment of a heel spring device <NUM> for an article of footwear <NUM> shown in <FIG>. The heel spring device <NUM> has similar function and features as heel spring device <NUM>. For example, the device <NUM> has the control bar <NUM> with the medial side arm <NUM> and lateral side arm <NUM>. The device <NUM> has the continuous base <NUM> that connects the side arms <NUM>, <NUM> and extends rearward from a junction of the control bar <NUM> with the base <NUM>. The base <NUM> underlies the control bar <NUM> with the first side arm <NUM> at a medial side <NUM> of a footwear upper <NUM>, the second side arm <NUM> at a lateral side <NUM> of the footwear upper <NUM>, and the center segment <NUM> of the control bar <NUM> rearward of the ankle opening <NUM> of the footwear upper <NUM>.

The base <NUM> supports the control bar <NUM> and is connected to the control bar <NUM> at resiliently bendable junction 3224A, 3224B. The base <NUM> is continuous and extends between and connects to the first side arm <NUM> and the second side arm <NUM>. The base <NUM> is continuous in that it is without breaks or connections through other components in extending from the first side arm <NUM> to the second side arm <NUM>. The base <NUM> has a center segment <NUM>, a first base arm <NUM>, and a second base arm <NUM> all disposed in a common plane, as described with respect to the device <NUM> of <FIG>. The first base arm <NUM> is spaced apart from the second base arm <NUM> and both extend from the center segment <NUM> of the base <NUM>.

The junction 3224A, 3224B includes a first joint 3224A at which the base <NUM> and the first side arm <NUM> connect, and a second joint 3224B at which the base <NUM> and the second side arm <NUM> connect. The first joint 3224A is the connection of the first base arm <NUM> to the first side arm <NUM>. The second joint 3224B is the connection of the second base arm <NUM> to the second side arm <NUM>. The joints 3224A, 3224B may be referred to herein as hinged joints, or as a hinged junction.

The control bar <NUM> has an arced shape from the first joint 3224A to the second joint 3224B. Similarly, the base <NUM> has an arced shape from the first joint 3224A to the second joint 3224B. With this arrangement, the control bar <NUM> and the base <NUM> are configured as a full elliptical leaf spring as described herein. The device <NUM> may be referred to as a heel spring. Additionally, the device <NUM> is a single, unitary, one-piece component. For example, the device <NUM> may be injection molded as a single, unitary, one-piece component.

The center segment <NUM> of the control bar <NUM> has the ramped surface <NUM> that declines toward an inner periphery of the center segment <NUM> between the first side arm <NUM> and the second side arm <NUM> and helps direct the foot downward and forward into the foot-receiving cavity <NUM> during application of the downward force F on the control bar <NUM> as described with respect to device <NUM>. Additionally, the first side arm <NUM> and the second side arm <NUM> are each twisted outwardly along their respective longitudinal axis from the junction 3224A, 3224B near the base <NUM> to the center segment <NUM> of the control bar <NUM>. The outward twist helps to encourage the down and back movement of the center segment <NUM> during loading by the foot.

The article of footwear <NUM> includes a sole structure <NUM>, and the flexible footwear upper <NUM> has a medial side <NUM> and a lateral side <NUM>, and defines an ankle opening <NUM> and a foot-receiving cavity <NUM>, as described with respect to the article of footwear <NUM>. The sole structure <NUM> includes one or more sole components that may be sole layers, such as an outsole, a midsole, or a sole layer <NUM> that is a unitary combination of an outsole and a midsole and may be referred to as a unisole. The sole layer <NUM> underlies the upper <NUM> and the foot-receiving cavity <NUM> defined by the upper <NUM>. A lower portion <NUM> of the footwear upper <NUM> is secured to the sole layer <NUM>, such as by adhesive or otherwise. The base <NUM> is secured to the sole layer <NUM> such as by bonding with adhesive, thermal bonding, or otherwise.

As best shown in <FIG>, the sole layer <NUM> has a slight recess <NUM> in the outer wall <NUM> of the sole layer <NUM> (i.e., in the outer side walls and rear wall in the heel region of the sole layer <NUM>). The recess <NUM> is shaped to allow the base <NUM> and joints 3224A, 3224B to partially nest in the recess <NUM>. The portions of the base <NUM> and the joints 3224A, 3224B nested in the recess <NUM> are secured to the outer wall <NUM> of the sole layer <NUM> in the recess <NUM>. The device <NUM> is thus supported by the sole layer <NUM> in the recess <NUM>.

The control bar <NUM> is biased to an unloaded position shown in <FIG> and <FIG>. The unloaded position is also referred to herein as an unstressed position. The control bar <NUM> is internally biased to the unstressed position by its material in its formed state. Stated differently, the material of the control bar <NUM> is sufficiently rigid that it remains in the unstressed position in its natural state without external loads applied to it, and will return to the unstressed position after elastic bending due to its resiliency. In the unstressed position, the center segment <NUM> is a first distance D1 from the bottom of the center segment <NUM> of the base <NUM>, as indicated in <FIG> by a distance D1 from the top of the center segment <NUM> of the control bar <NUM> to the bottom of the center segment <NUM> of the base <NUM>. The unstressed position is the position of the device <NUM> in a relaxed, unloaded state (i.e., without a vertical force applied to the control bar <NUM>). The control bar <NUM> can be depressed under an applied force F shown in <FIG>, representing the force applied by a foot during insertion of the foot into the foot-receiving cavity <NUM> (see, e.g., <FIG>) of the article of footwear <NUM>. When loaded in this manner, the control bar <NUM> elastically bends to a loaded position in which the top of the center segment <NUM> is a second distance D2 from the bottom of the center segment <NUM> of the base <NUM>. The loaded position is shown in <FIG>, in which the control bar <NUM> and the center segment <NUM> are indicated with phantom lines, and the center segment is indicated with reference number 16A in <FIG>. The second distance D2 is less than the first distance D1. The difference between the distances D1 and D2 is the deflection of the device <NUM>, which may be but is not limited to a deflection of <NUM>. The device <NUM> is configured so that when it is depressed under the force F to the loaded position D2, it elastically bends at the junction 3224A, 3224B, storing elastic energy. When the force F is removed, the stored elastic energy returns the control bar <NUM> to the unstressed position. Like device <NUM>, the first side arm <NUM> and the second side arm <NUM> extend at a first acute angle A1 to the common plane P of the base <NUM> when the control bar <NUM> is in the unloaded position. The first side arm <NUM> and the second side arm <NUM> extend at a second acute angle A2 to the common plane P of the base <NUM> when the control bar <NUM> is depressed. The second acute angle A2 is less than the first acute angle A1.

As best indicated in <FIG>, the base <NUM> extends around a rearmost portion of the footwear upper <NUM> from the lateral side <NUM> to the medial side <NUM>. As indicated in <FIG>, the device <NUM> is not secured to the upper <NUM> at the medial side <NUM> or the lateral side <NUM>. Instead, the device <NUM> is only secured to the upper <NUM> via a heel tab <NUM> that extends through an aperture <NUM> in the center segment <NUM>. The tab <NUM> is then stitched to a rear portion <NUM> of the upper <NUM> at stitching <NUM>. A decorative snap <NUM> may be secured to the tab <NUM>. However, in the embodiment shown, the decorative snap <NUM> is merely decorative in that it does not snap or otherwise fasten to the upper <NUM>.

<FIG> best illustrates that the medial side arm <NUM> and the lateral side arm <NUM> are asymmetrical about a longitudinal axis L extending between the medial side arm <NUM> and the lateral side arm <NUM> through the base <NUM>. The medial side arm <NUM> is also referred to herein as a first side arm, and the lateral side arm <NUM> is also referred to as a second side arm. The medial side arm <NUM> may be shorter than the lateral side arm <NUM> and may be have a greater lateral (i.e., outward) curvature than the lateral side arm, similar to the shape of a typical heel region of a foot. Because the heel device <NUM> is asymmetrically shaped in this manner following a typical foot shape, pressure of the heel device <NUM> against the sides of the foot during wear is thus minimized.

<FIG> illustrate another embodiment of a heel spring device <NUM> that has many of the same features as heel spring device <NUM>, <NUM>, which features are referenced with like reference numbers. Additionally, the base <NUM> has an inwardly-extending flange <NUM> that extends continuously from the medial base side arm <NUM>, around the center segment <NUM> to the lateral base side arm <NUM> such that the flange <NUM> generally has a U-shape.

With reference to <FIG>, the heel spring device <NUM> is included in an article of footwear <NUM> that has an upper <NUM> and a sole structure <NUM>. The upper <NUM> is as described herein with respect to heel spring device <NUM>, and is shown only in phantom in <FIG>. The sole structure <NUM> includes an outer sole layer <NUM> that may serve as a unitary outsole and midsole. The sole structure <NUM> also includes an inner sole layer <NUM>, also referred to as an insole, that overlays the sole layer <NUM>. <FIG> shows the sole layer <NUM> alone with the inner sole layer <NUM> removed. The sole layer <NUM> has a recess <NUM> in an upper surface <NUM>. The recess <NUM> is shaped so that the flange <NUM> is seated in and at least partially nested in the recess <NUM>, and secured to the upper surface <NUM> in the heel region of the sole structure <NUM>. <FIG> shows the flange <NUM> seated in the recess <NUM>. The heel spring device <NUM> is secured to the sole layer <NUM> by securing the flange <NUM> to upper surface <NUM> of the sole layer <NUM> in the recess <NUM> by thermal bonding, by adhesive, or otherwise. The inner sole layer <NUM> is then inserted in the upper <NUM> to rest on the sole layer <NUM> over the flange <NUM> and at the upper surface <NUM> of the sole layer <NUM>.

As best indicated in <FIG>, the heel spring device <NUM> is asymmetric about the longitudinal axis L. More specifically, the medial side arm <NUM> curves laterally outward more than the lateral side arm <NUM>, and is also longer in a fore-aft direction (along the longitudinal axis L) than the lateral side arm <NUM>. As discussed with respect to heel spring device <NUM>, this is a more anatomical shape than a symmetrical heel spring device, and avoids undesirable friction and pressure of the side arms <NUM>, <NUM> on the foot.

The heel spring device <NUM> is configured to secure to the upper <NUM> at forwardmost portions of the side arms <NUM>, <NUM>, and via a heel tab extending through an aperture <NUM> of the center segment <NUM> as indicated with respect to the upper <NUM> shown in phantom in <FIG>. More specifically, a forwardmost portion <NUM> of an inner surface <NUM> of the first side arm <NUM> includes a medial recess <NUM> such that the first side arm <NUM> is thinner at the medial recess <NUM> than rearward of the medial recess <NUM>. A forwardmost portion <NUM> of an inner surface <NUM> of the second side arm <NUM> includes a lateral recess <NUM> such that the second side arm <NUM> is thinner at the lateral recess <NUM> than rearward of the lateral recess <NUM>. The upper <NUM> may be secured to the first side arm <NUM> at the medial recess <NUM> and to the second side arm <NUM> at the lateral recess <NUM>. For example, the upper <NUM> may be bonded to the side arms <NUM>, <NUM> at the recesses <NUM>, <NUM>. In some embodiments, the upper may include an inner portion 38B, and an outer portion 38A, as shown in <FIG>. In such embodiments, the outer portion 38A may include rearward-extending flanges 38C that are thinner than more forward portions of the outer portion 38A. The flanges 38C interfit with and are secured to the inner surfaces <NUM>, <NUM> of the side arms <NUM>, <NUM> in the recesses <NUM>, <NUM>. The outer portion 38A may be less flexible than the inner portion 38B, and may thus provide better anchoring support to the device <NUM> at the arms <NUM>, <NUM> than would the inner portion 38B.

In addition to attaching to the upper <NUM> (or outer portion 38A) at the forwardmost portions <NUM>, <NUM>, the upper <NUM> may be secured to the heel spring device <NUM> via a heel tab <NUM> (see <FIG> and <FIG>). The heel tab <NUM> extends through an aperture <NUM> in the center segment <NUM>. After the tab <NUM> is extended through the aperture <NUM>, the tab <NUM> may be folded over in a loop and stitched to itself at stitching <NUM> as shown in <FIG>. A pin <NUM> may then be inserted into an opening <NUM> in the loop of the tab <NUM>. The pin <NUM> may be secured to the tab <NUM> in the opening <NUM> rearward of the aperture <NUM>, such as by inserting adhesive into the opening <NUM>. The tab <NUM> with the pin <NUM> therein may be wider than the aperture <NUM>. For example, the pin <NUM> has a width <NUM> (see <FIG>) which is greater than the width <NUM> of the aperture <NUM>. With the pin <NUM> inserted into the looped tab <NUM>, after pulling the tab <NUM> through the aperture <NUM>, the pin <NUM> helps retain the tab <NUM> in its position extended through the aperture <NUM> and therefore helps to secure the upper <NUM> to the device <NUM> via the tab <NUM>. The tab <NUM> is thus anchored to the center segment <NUM> by the pin <NUM>.

<FIG> show a heel spring device <NUM> that has many of the same features as heel spring devices <NUM> and <NUM>. Like reference numbers are used to refer to such features. The device <NUM> includes a lever <NUM> that extends laterally outward from the control bar <NUM>. The lever <NUM> may also be referred to as a ledge extension or a shelf. The lever <NUM> is disposed partly along the medial side arm <NUM> and partly along the center segment <NUM>. Within the scope of the present disclosure, the lever <NUM> may be disposed anywhere along the control bar <NUM>. The lever <NUM> has an upward-facing surface <NUM> that may be depressed downward, in a similar manner as described with respect to force F on the center segment <NUM> in <FIG>. Depressing the lever <NUM> facilitates depression of the control bar <NUM> from the unstressed position to the stressed position. The surface <NUM> has recessed grooves <NUM> such that the surface <NUM> is not smooth, enhancing the ability to grip the surface <NUM> when depressing the lever <NUM>. <FIG> shows a rear view of an article of footwear <NUM> that includes the device <NUM> secured to a sole layer <NUM> and to the upper <NUM>.

The various embodiments of heel spring devices disclosed herein enhance the ease of foot entry, allowing hands free foot entry into an article of footwear.

All references referred to are incorporated herein in their entirety.

Claim 1:
A device (<NUM>, <NUM>) for easing foot entry into an article of footwear and configured to surround a portion of a foot-receiving cavity at a heel region of the article of footwear, the device (<NUM>, <NUM>) comprising:
a control bar (<NUM>) having:
a center segment;
a medial side arm (<NUM>) extending downwardly and forwardly from the center segment; and
a lateral side arm (<NUM>) extending downwardly and forwardly from the center segment;
wherein the control bar pivots rearward under an applied force to a loaded position, storing potential energy that returns the control bar to an unloaded position upon removal of the applied force;
wherein the lateral side arm (<NUM>) first extends rearward, then forward, then rearward again in progressing to the center segment of the control bar (<NUM>), establishing a Z shape.