Footwear heel spring device
A device configured to surround a portion of a foot-receiving cavity at a heel region of an article of footwear comprises a control bar having a center segment, a first side arm extending from the center segment, and a second side arm spaced from the first side arm and extending from the center segment. The control bar may include a series of slats. A base supports the control bar and is connected to the first side arm and the second side arm. The control bar is biased to an unstressed 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 that returns the control bar to the unloaded position upon removal of the applied load.
1. A device for easing foot entry into a foot-receiving cavity at a heel region of an article of footwear, the device comprising:
a control bar and a base, the control bar having:
a center segment;
a medial side arm extending downwardly and forwardly from the center segment; and
a lateral side arm extending downwardly and forwardly from the center segment and spaced apart from the medial side arm;
wherein:
the base is connected to the control bar at a junction at a forward portion of the medial side arm and at a forward portion of the lateral side arm and extends transversely from the forward portion of the medial side arm to the forward portion of the lateral side arm under the foot-receiving cavity;
the base extends forward from the junction of the control bar with the base and rearward from the junction of the control bar with the base;
the base has a forward-extending protrusion and a rearward-extending protrusion; and
the rearward-extending protrusion is only at a lateral side of the base between a longitudinal midline of the device and the lateral side arm or is only at a medial side of the base between the longitudinal midline and the medial side arm.
2. The device of claim 1 , wherein the device is a single, unitary, one-piece component.
3. The device of claim 1 wherein the base tapers in width as it extends rearward.
4. The device of claim 1 , wherein:
a notch is defined in a rear edge of the base between the rearward-extending protrusion and the lateral side arm.
5. The device of claim 1 , wherein:
the base has a main portion and a protrusion extending downward from the main portion;
the protrusion forms a cavity; and
the cavity is enclosed except at the main portion.
6. The device of claim 1 , wherein the base has two rearward-extending protrusions, one of the rearward-extending protrusions at the medial side of the base between the longitudinal midline and the medial side arm and one of the rearward-extending protrusions at a lateral side of the base between the longitudinal midline and the lateral side arm.
7. The device of claim 1 , wherein:
the medial side arm has at least one slot extending lengthwise through the medial side arm along a longitudinal axis of the medial side arm;
the lateral side arm has at least one slot extending lengthwise through the lateral side arm along a longitudinal axis of the lateral side arm; and
the at least one slot extending lengthwise through the medial side arm is separate from the at least one slot extending lengthwise through the lateral side arm.
8. The device of claim 1 , wherein:
the medial side arm has multiple slots extending through the medial side arm transversely to a longitudinal axis of the medial side arm such that the medial side arm defines fingers between adjacent ones of the multiple slots in the medial side arm; and/or
the lateral side arm has multiple slots extending through the lateral side arm transversely to a longitudinal axis of the lateral side arm such that the lateral side arm defines fingers between adjacent ones of the multiple slots in the lateral side arm.
9. The device of claim 1 , wherein:
the medial side arm and the lateral side arm resiliently bend to a loaded position when a downward force is applied to the center segment, storing potential energy that returns the control bar to an unloaded position upon removal of the downward force; and
a height of the center segment relative to the base is less in the loaded position than in the unloaded position.
10. The device of claim 1 , wherein the center segment is further rearward than the rearward-extending protrusion such that the device defines a void between the control bar and the base that extends around a rear of the heel region and under the foot-receiving cavity.
11. An article of footwear comprising:
a footwear upper defining at least a portion of a foot-receiving cavity having an ankle opening;
a sole structure secured to and underlying the footwear upper; and
a device comprising a control bar and a base, the control bar operatively connected to the footwear upper and the base underlying the foot-receiving cavity;
wherein:
the control bar includes a center segment disposed rearward of the ankle opening, a medial side arm extending downwardly and forwardly from the center segment at a medial side of the footwear upper, and a lateral side arm extending downwardly and forwardly from the center segment at a lateral side of the footwear upper;
the base is connected to the control bar at a junction at a forward portion of the medial side arm and at a forward portion of the lateral side arm and extends transversely from the forward portion of the medial side arm to the forward portion of the lateral side arm under the foot-receiving cavity;
the base has a main portion and a protrusion extending downward from the main portion;
the protrusion forms a cavity;
the protrusion seats in a recess of a foot-facing surface of the sole structure; and
the cavity is enclosed except at the main portion.
12. The article of footwear of claim 11 , wherein:
the base extends rearward from the junction of the control bar with the base; and/or
the base extends forward from the junction of the control bar with the base.
13. The article of footwear of claim 11 , wherein the base has a forward-extending protrusion adjacent the medial side of the footwear upper and a rearward-extending protrusion adjacent the lateral side of the footwear upper.
14. The article of footwear of claim 11 , further comprising:
a strobel; wherein the base underlies the strobel.
15. The article of footwear of claim 14 , wherein:
the sole structure includes a sole layer; and
the base is between the strobel and the sole layer.
16. The article of footwear of claim 11 , wherein:
the sole structure includes a sole layer; and
the base extends through openings in the sole layer at the medial and lateral side arms and is secured to or embedded in the sole layer.
17. The article of footwear of claim 11 , wherein:
the medial side arm and the lateral side arm resiliently bend to a loaded position when a downward force is applied to the center segment, storing potential energy that returns the control bar to an unloaded position upon removal of the downward force;
a height of the center segment relative to the base is less in the loaded position than in the unloaded position; and
a rear of the footwear upper moves with the center segment such that the ankle opening is lower at the rear of the footwear upper in the loaded position.
18. A device for easing foot entry into a foot-receiving cavity at a heel region of an article of footwear, the device comprising:
a control bar and a base, the control bar having:
a center segment;
a medial side arm extending downwardly and forwardly from the center segment; and
a lateral side arm extending downwardly and forwardly from the center segment and spaced apart from the medial side arm;
wherein:
the base is connected to the control bar at a junction at a forward portion of the medial side arm and at a forward portion of the lateral side arm and extends transversely from the forward portion of the medial side arm to the forward portion of the lateral side arm under the foot-receiving cavity;
the base extends forward from the junction of the control bar with the base and rearward from the junction of the control bar with the base;
the base has a forward-extending protrusion and a rearward-extending protrusion; and
one of the forward-extending protrusion and the rearward-extending protrusion is only at a lateral side of the base between a longitudinal midline of the device and the lateral side arm and the other of the forward-extending protrusion and the rearward-extending protrusion is only at a medial side of the base between the longitudinal midline and the medial side arm.
19. The device of claim 18 , wherein the device is a single, unitary, one-piece component.
20. The device of claim 18 , wherein the center segment is further rearward than the rearward-extending protrusion such that the device defines a void between the control bar and the base that extends around a rear of the heel region and under the foot-receiving cavity.