Lever plate for shoes

Abstract

The shoe according to the present invention applies a special lever mechanism to the sole to maintain heel contact and absorb shock. The shoe may consist of a semi-rigid lever plate embedded inside or on top of the midsole, a strategically placed support structure, and a clearance space capable of controlling movement. Furthermore, the proposed components, ranging from a curved lever structure to a compressible forefoot pad and a plate reinforcement structure, can increase the effect of the invention by reducing the accumulation of heat and shock on the heel and providing comfortable fixation when the user walks or runs.

Description

Technology Field

[0001] The present invention relates to shoes. Background Technology

[0002] Shoes are required not only to protect the feet by wrapping them, but also to make walking more comfortable and improve the efficiency of various exercises and tasks.

[0003] The structure of a typical shoe is illustrated in FIG. 1. The upper (50) is the upper part of the shoe that covers and secures the foot. The upper (50) wraps around the top (inside) of the foot and is generally made of leather, mesh, or synthetic material for support and breathability. The upper (50) secures the foot in place inside the shoe with laces or fasteners. The insole (30) is the inner footbed of the shoe where the foot touches, serving as the inner bottom layer that comes into direct contact with the foot. The insole (30) is often padded and is sometimes removable to provide initial cushioning, and in some designs, provides moisture absorption or antibacterial functions to provide comfort. The midsole (20) is the layer located between the insole (or upper) and the outsole. It runs along the length of the foot of the shoe and serves as the primary shock-absorbing and cushioning structure. Midsole materials (e.g., EVA foam, PU foam, TPU foam) are selected for elasticity and shock damping. This component is considered the 'heart' of the shoe because it largely determines the fit and firmness. The outsole (10) is the outermost bottom part of the shoe that comes into direct contact with the ground. It is a thin, durable layer, typically made of rubber or a similar abrasion-resistant material, that provides traction and protects the midsole (20). The tread pattern and compound of the outsole (10) affect traction and contribute to the overall durability of the shoe. The cushion pad (40) is a padding element placed over the insole (30) of the shoe to enhance cushioning. Examples include heel pads, metatarsal pads, or inserts that absorb shock in specific high-pressure areas.

[0004] Meanwhile, it is common to experience discomfort due to heat accumulation in the heel area when walking or running for extended periods in shoes. When a person walks, the heel lifts first and momentarily separates from the insole; as the foot descends, the forefoot lands before the heel, causing the separated heel to strike the insole. This repetitive heel collision and slipping generate friction and impact heat in the heel with every step. Over time, the heat accumulated in the heel area and the resulting sweat cause significant discomfort and a slippery sensation. Attempts to alleviate this by tightening the laces only create new problems. Tightening them excessively increases pressure and fatigue on the foot and hinders ventilation, causing sweat to accumulate more quickly. In summary, conventional shoes induce friction heat and moisture accumulation due to excessive heel movement, reducing comfort during prolonged use. The problem to be solved

[0005] The present invention aims to solve the problems of the aforementioned prior art by providing a shoe lever plate that minimizes heat generation caused by friction and impact on the heel and maintains a stable yet comfortable fit.

[0006] Another objective of the present invention is to prevent internal friction that generates heat by maintaining constant contact between the heel and the insole throughout the walking or running cycle. This aims to reduce sweat and discomfort in the shoe during long periods of walking or running.

[0007] Additionally, it aims to improve long-term comfort and performance through a new sole structure that manages heel impact and heat without overtightening the laces or compromising breathability.

[0008] The present invention provides a shoe equipped with a special lever-type support structure developed to achieve the aforementioned purpose. Furthermore, the objectives of the present invention are not limited to those mentioned above, and other unmentioned objectives will be clearly understood from the description below. means of solving the problem

[0009] A shoe using a lever mechanism according to the present invention comprises a lever plate disposed between an upper sole and a lower sole, wherein the lever plate comprises: a pulcrum portion formed along a transverse arch formed at the bottom of a human foot; a front portion disposed at the forefoot and extending upwardly inclined from the pulcrum portion; and a rear portion extending from the pulcrum portion to the rearfoot portion; wherein the rear portion of the lever plate is tightly fixed between the upper sole and the lower sole, and a gap space is formed between the bottom surface of the front portion of the lever plate and the lower sole.

[0010] It is preferable that at least a portion of the bottom surface of the front portion extending from the pulcrum portion is formed as a curved surface.

[0011] In addition, it is preferable that a cushion member with a deformation rate greater than that of the lower sole is disposed in the gap space.

[0012] In addition, a heel support portion formed by bending upward can be formed at the end of the rear portion.

[0013] And, the pulcrum portion may include a knob formed by protruding from the bottom surface of the lever plate.

[0014] Furthermore, a groove extending in the longitudinal direction may be formed in the rear portion of the lever plate. Effects of the invention

[0015] A shoe utilizing a lever mechanism according to the present invention provides various performance and comfort by reducing heat accumulation caused by friction, redistributing impact forces, and optimizing energy transfer. The applied lever plate minimizes repetitive friction and heat accumulation by ensuring the heel remains in constant contact with the insole, helping to maintain a cool and dry environment for the foot even during prolonged wear. The force applied to the forefoot is partially redistributed to lift the heel, improving energy efficiency to enable smoother transitions and reduce muscle tension. Furthermore, it prevents excessive heel slippage without the need for overtightening of laces, thereby enhancing overall foot stability. Additionally, strategic stress distribution and the use of a highly durable lever plate material reinforce the mechanical stability of the shoe, extending its lifespan and preserving cushioning. Focusing on heat reduction, shock absorption, and efficient biomechanics, a shoe equipped with the lever plate according to the present invention can provide long-lasting protection, support, and performance during various activities. Brief explanation of the drawing

[0016] Figure 1 is a drawing illustrating the cross-sectional structure of a conventional shoe. FIG. 2 is a cross-sectional view schematically illustrating the sole structure of a shoe according to one embodiment of the present invention. FIG. 3 is a plan view illustrating, exemplarily, the position where a lever plate applied to a shoe according to the present invention is placed. FIG. 4 is a perspective view illustrating the shape of a lever plate according to another embodiment of the present invention. Figure 5 is a partial cross-sectional view of the structure of the pulcrum section along the cutting line II of Figure 4. FIG. 6 is a partial cross-sectional view showing the shape of a groove formed in the rear portion of a lever plate according to the present invention along the II-II cut line. FIG. 7 is a cross-sectional view schematically illustrating the operating state of the lever plate on the wearer's foot (F) when walking while wearing the shoe according to the present invention. Specific details for implementing the invention

[0017] In describing the present invention, if it is determined that a detailed description of related prior art could unnecessarily obscure the essence of the invention, such detailed description is omitted.

[0018] Furthermore, when it is stated that one component is 'connected,' 'supported,' 'connected,' 'supplied,' 'transmitted,' or 'contacted' with another component, it should be understood that the connection, support, connection, transmission, or contact may be direct to that other component, or that other components may exist in between.

[0019] Furthermore, it should be noted in advance that expressions such as upper side, lower side, side, top, bottom, bottom, and side in this specification are described based on what is shown in the drawings, and may be expressed differently if the orientation of the object changes. For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted, and the size of each component does not entirely reflect its actual size.

[0020] Furthermore, terms including ordinal numbers such as first, second, etc., used in the description of this specification may be used to describe various components, but are used solely for the purpose of distinguishing said components from other components.

[0021] And, the meaning of 'comprising' as used in the specification specifies certain characteristics, regions, integers, steps, actions, elements, and / or components, and does not exclude the existence or addition of other specific characteristics, regions, integers, steps, actions, elements, components, and / or groups.

[0022] Hereinafter, specific details for implementing the present invention will be described with reference to the attached drawings.

[0023] The shoe system according to the present invention introduces a special lever mechanism in the sole to maintain heel contact and absorb shock. The shoe consists of a semi-rigid lever plate embedded inside or on top of the midsole, a strategically placed support structure, and a clearance space capable of controlling movement. The main components of the shoe structure according to the present invention and their functions will be described in detail with reference to FIGS. 2 through 7.

[0024] FIG. 2 is a cross-sectional view schematically illustrating the sole structure of a shoe according to one embodiment of the present invention, FIG. 3 is a plan view exemplarily illustrating the position where a lever plate applied to the shoe according to the present invention is positioned relative to the wearer's foot (F), FIG. 4 is a perspective view illustrating the shape of a lever plate according to another embodiment of the present invention, FIG. 5 is a partial cross-sectional view illustrating the structure of the pulcrum portion along the cutting line II of FIG. 4, FIG. 6 is a partial cross-sectional view illustrating the shape of a groove formed in the rear portion of the lever plate according to the present invention along the cutting line II-II, and FIG. 7 is a cross-sectional view schematically illustrating the operating state of the lever plate relative to the wearer's foot (F) when walking while wearing the shoe according to the present invention.

[0025] A shoe according to the present invention comprises a lever plate (100) disposed between an upper sole (210) and a lower sole (220), wherein the lever plate (100) comprises: a pulcrum portion (110) formed along a transverse arch formed at the bottom of the human foot; a front portion (120) disposed at the forefoot and extending from the pulcrum portion (110) and formed to be inclined upward; and a rear portion (130) extending from the pulcrum portion (110) to the rearfoot. Furthermore, the rear portion (130) of the lever plate (100) is fixed in close contact between the upper sole (210) and the lower sole (220), and a gap space portion (160) is formed between the bottom surface of the front portion (120) of the lever plate (100) and the lower sole (210).

[0026] The upper sole (210) can be formed from a material generally used as a midsole. The lower sole (220) can be formed from a midsole material like the upper sole (210), composed of an outsole, or formed in a combined form of a midsole and an outsole. The upper sole (210) and the lower sole (220) may be formed as two physically separated soles, or may be formed in a form in which a lever plate (100) is inserted inside a single midsole layer. The upper sole (210) and the lower sole (220) firmly secure the rear portion (130) of the lever plate (100). For example, a plurality of openings (132) may be formed in the rear portion (130) to have a structure in which the upper sole (210) and the lower sole (220) are connected to each other.

[0027] Before providing a detailed description of the main components constituting the shoe according to the present invention, the structure of the human foot (F) is first described to facilitate a clear understanding. The forefoot is the front part of the foot, composed of five metatarsals and phalanges. This region corresponds to the ball of the foot and the toes. The forefoot is significantly involved in supporting body weight and propulsion during walking, and considerable force passes through the metatarsal heads when pushing off the ground. The metatarsal region is the middle part of the foot and consists of phalanges (mainly the fibula, cuboids, and three tongue bones) that form an arch. The metatarsals connect the forefoot and hindfoot and include the instep area. Structurally, they form the arch of the foot, providing elasticity and shock absorption. Located at the top of the longitudinal and transverse arches, they play an important role in distributing force. Although the metatarsal region is relatively rigid, slight flexion must be allowed for the foot to function like a spring. The hindfoot is the back part of the foot, consisting of the heel and ankle regions, primarily the calcaneus (heel bone) and talus. The hindfoot withstands the initial impact when the heel strikes the ground. It forms the posterior pillar of the plantar arch, handles significant impact forces when the heel hits the ground, and provides stability. The first metatarsal head is the head of the first metatarsal (the bone immediately behind the big toe) and serves as an important weight-bearing point on the front of the foot (W1 in Fig. 3). It is located at the intersection of the medial longitudinal arch and the transverse arch of the foot. During walking, a significant portion of body weight is transmitted through the first metatarsal head because it is larger and stronger than the lower metatarsals. The 'ball of the foot' below the big toe joint helps support high pressure and provide propulsion during toe lift. The fifth metatarsal head is the head of the fifth metatarsal (the part under the little toe) and serves as a support point (W2 in Fig. 3) located at the intersection of the lateral longitudinal arch and the transverse arch. Generally, it bears much less weight than the first metatarsal head. Because most of the load is transferred to the inside (medial) of the foot and the heel, the lateral metatarsal head is smaller and accounts for a smaller portion of the weight during normal gait.However, it is involved in the balance and stability of the forefoot's side. The calcaneus (heel bone) is a large bone that forms the heel of the foot. Generally, it is the part of the foot that first touches the ground when walking or running (W3 in Fig. 3). Although the calcaneus withstands the greatest impact force among the foot bones, it lacks an intrinsic cushioning mechanism other than the natural fat pad underneath it.

[0028] Given the anatomical structure of the foot, preventing the calcaneus from striking the shoe and managing impact is very important for reducing shock and heat. The transverse arch spans the width of the forefoot formed by the metatarsal heads and distal metatarsals and is formed across the sole of the foot. It extends across the ball of the foot, approximately from the first metatarsal head to the fifth metatarsal head. This arch allows the foot to adapt to uneven ground and helps distribute body weight between the medial and lateral sides. In the present invention, the pulcrum portion (110) of the lever plate installed in the shoe is roughly aligned along the transverse arch area (below the ball of the foot), because this is where the forefoot naturally supports body weight just before lifting the heel.

[0029] A shoe comprising a lever plate according to the present invention is designed using a lever mechanism. Generally, a lever (lever system) is a simple mechanism consisting of a rigid beam that rotates around a point called a fulcrum. When a force (input force) is applied to one side of the fulcrum, a rotational moment (torque) is generated that can lift or overcome the load (resistance force) on the other side. Essentially, the lever exchanges force and distance. A small downward movement on the force side leads to an upward movement on the load side. The lever system applied to the shoe according to the present invention uses the forefoot as the 'force' (the side applying force through body weight) and the heel portion of the shoe as the 'load' that lifts it, with a fulcrum between them. The fulcrum (fulcrum) is a pivot point or support where the lever rotates. It may be formed over a relatively wide area or simply in the form of a contact point or a tangential line. In a primary lever such as a seesaw, the fulcrum is located between the force and the load. In the shoe system according to the present invention, the lever plate refers to a structure embedded beneath the sole of the foot. When the forefoot is pressed down (force), the lever plate rotates to allow the heel to be lifted. The position and design of the lever plate are very important. It must be sturdy enough to support the force and ideally positioned where the foot naturally rotates during walking.

[0030] The lever plate (100) is a rigid, plate-shaped element embedded in the sole that extends roughly from the forefoot to the hindfoot. It acts as a lever within the shoe. When the wearer's forefoot takes a stride, the lever plate uses that force (the degree of leverage) to lift the heel portion of the shoe, keeping it snug against the foot. In effect, the lever plate prevents the heel of the foot from separating from the insole during the swing phase and initial contact phase of walking or running. By maintaining this contact, it prevents sudden friction that generates heat upon heel impact. To perform the lever function effectively, the plate must have sufficient rigidity. The plate has high tensile and flexural rigidity. It must be constructed from a material capable of transmitting force without simply bending or warping. In practice, this plate can be made from thin spring steel alloys, carbon fiber composites, or strong synthetic resins. In particular, it is desirable for the lever plate to be formed from a semi-rigid material. A "semi-rigid body" is a material that possesses characteristics between a fully rigid body and a flexible body; while a rigid body is an ideal object that does not deform even when external force is applied, a semi-rigid body undergoes some degree of deformation when external force is applied, but this deformation is limited and largely maintains its original shape. For example, reinforced plastics or high-rigidity composite materials can be used as semi-rigid materials. These materials can provide the rigidity necessary to lift the heel of the shoe using the force of the forefoot, while also offering some elasticity (the phenomenon of bending slightly and springing back under load). The lever plate can be formed from a material that bends slightly under body weight but is rigid enough to lift the heel of the shoe. The rigidity of the plate must be carefully balanced. It must be firm enough to transmit force and support the rear foot, but not so stiff that the shoe becomes uncomfortablely inflexible. A slight elasticity in the plate helps to smooth movement. The lever plate can be a separate insert piece or part of a structured midsole. In both cases, it extends from the ball of the foot (where force is applied) toward the heel, effectively connecting the two areas.

[0031] An important point is that the shape of the lever plate, which acts as a lever, is designed with a smooth curvature rather than a sharp hinge. The portion of the plate (the middle part of the foot) that passes over the fulcrum (110) is bent into a continuous, smooth curve. This contrasts with a hypothetical design that has a simple angled joint. The smooth curve allows contact and force transfer to be gradually distributed as the plate bends over the fulcrum (the fulcrum). Sudden angles can concentrate stress and cause friction at one point, potentially leading to energy loss and material fatigue. Using a rounded lever plate profile allows force to be distributed along the curve, resulting in smoother operation, less friction, and improved durability. In other words, when the front end of the plate is pressed, the plate smoothly enters the fulcrum pivot without sudden impact, thus avoiding abrupt transitions that could cause shaking or wear. While an angled lever may provide a temporarily higher mechanical advantage, energy is wasted over friction, and stress is concentrated, making it prone to damage, thus increasing overall mechanical efficiency. The smooth curvature of the lever plate around the pulcrum (110) can ensure stable and long-lasting performance even under repetitive loads.

[0032] The fulcrum (110) is a pivot point or line on which the lever plate (100) rotates. Structurally, it can be implemented as a slightly protruding support or a fixed support in the midsole on which the lever plate is placed or fixed. The position of the fulcrum (110) is aligned with the part of the foot that initially supports weight during inversion (along the transverse arch spanning approximately the heads of the first to fifth metatarsals). In practice, this means that the fulcrum moves from side to side under the metatarsal / forefoot area (ball of the foot). When the wearer steps on the forefoot, the force is concentrated near this pivot line. Assuming that the ball of the foot (specifically the heads of the first and fifth metatarsals) presses against the sole when stepping and lifting the toes, the lever finds a support point at this point. The lever structure can be designed as a ridge or rod embedded in the sole, or as a series of structures supporting the lever plate from below. It does not need to align exactly with the anatomical transverse arch, but is positioned to align it approximately. The transverse arch of the foot (across the metatarsal heads) provides a convenient guideline for placement, but the precise position of the pulcrum can be adjusted according to shoe size and design to ensure the lever plate is effectively secured at the correct point. A slight deviation from the anatomical arch is permitted as long as it serves as the pivot for the lever. The pulcrum can be a straight or slightly curved support line.

[0033] To enhance pivot motion, a protruding 'pivot bump' structure may be formed on the underside of the lever plate. For example, the lever plate (100) has a raised or protruding knob (111), which is located in the fulcrum area. This local protrusion (knob) concentrates the contact points into a smaller area and acts like an individual hinge point. As a result, the lever plate swings more easily over this protrusion, enhancing the function of the lever, such as improving the consistency of the pivot motion. Additionally, the protruding fulcrum structure increases the local thickness and rigidity of the plate at that point, helping the plate rotate as intended without bending immediately at the pivot. The base surface is designed to be slightly raised or rounded to prevent slipping, and the lever is 'secured' to the base when under load. Thanks to this small but important feature, when the front foot is pressed down, the rotation of the plate is well defined around the lever, allowing the rear part to be lifted efficiently.

[0034] The front portion of the lever plate (the front of the lever plate) extends toward the toes. The front portion (120) located at the front of the lever plate is the part that the wearer's forefoot presses against. The front portion (120) is positioned at the forefoot, i.e., the toes, and is formed to be inclined upward by extending from the pulcrum portion (110). The angle of inclination (R) of the front portion (120) can be formed at an appropriate angle depending on the size of the wearer's foot. When weight is transferred to the ball of the foot during normal use (e.g., when the opposite foot swings forward), the front portion (120) of the lever plate is pressed downward (direction A in FIG. 7). In the present invention, a dedicated space provided in the forefoot portion (described below) is designed to allow the front portion (120) to move downward to accommodate this movement. Thus, the front lever section acts as the 'effort arm' of the lever system. As mentioned above, the part where the front portion (120) and the pulcrum portion (110) meet is smoothly curved. The section connecting the forefoot (120) to the fulcrum (110) is a continuous curve, intentionally shaped with a curvature to maximize force transfer and avoid weaknesses. Thanks to this curvature, when the forefoot is loaded and bent downwards, sudden hinge movement does not occur; instead, it bends gradually and pushes the rear section upwards in a controlled manner. Because the lever profile is smooth, the transfer of force through the lever occurs more gradually, which can reduce sudden impact or energy loss. Essentially, the forefoot (120) "cames" smoothly over the fulcrum (110), similar to a camber spring, to improve the efficiency of force transfer and reduce deformation of the plate. Another consideration for the forefoot (120) is integration with the general flexibility of the shoe's forefoot. For toe-off and a natural gait, the forefoot (beyond the lever plate) must remain flexible. In shoe designs, there are often curved grooves in the outsole or foam to allow the ball of the foot to bend easily.In this lever system, the lever plate may end just behind the toes or have a cutout to keep the toe area of ​​the shoe flexible. The forefoot portion of the plate is primarily related to the ball of the foot. It must be firm enough to withstand the load when the forefoot is compressed, but it may taper or soften towards the front to allow the toes to bend.

[0035] The rear portion (130) of the lever plate (100) extends from the pulcrum portion (110) toward the heel of the shoe. This portion effectively transmits the load of the lever system and is the part that is lifted when the forefoot is pressed down. The rear portion of the shoe is fixed to the surrounding sole structure (midsole or outsole) so that the entire heel portion of the shoe moves upward during operation (direction B in FIG. 7). In practice, the rear end of the lever plate may be fixed or bonded to the heel portion of the midsole or outsole. Thus, the plate does not move independently but lifts the entire heel of the shoe together. This ensures that the heel collar of the shoe adheres to the heel of the foot. By fixing the rear portion of the lever plate to the shoe, the heel cup of the shoe is lifted when the plate is raised, preventing a gap from forming between the foot and the shoe. The rear portion (130) may be formed curved along the longitudinal arch of the foot, but is not necessarily limited to this and may be formed as a flat surface. If the lower portion (130) has an upwardly convex structure as in FIG. 4, a downwardly convex support line (140) can be formed along the weight support point (W3) of the heel.

[0036] To more firmly secure the wearer's heel and eliminate relative movement, a heel support cup design may be applied to the rear portion of the lever plate. Specifically, a heel support (150) is formed at the very rear end of the plate (around the calcaneus) so that the plate (or attached component) rolls up to support the heel bone. Thus, the rear portion of the lever plate is formed to curve upward to wrap around the heel, rather than being a flat portion under the heel. The heel support (150) can be accommodated in a "heel cup" or "heel counter" that wraps around the back of the calcaneus. When the lever is lifted, the heel cup adheres to the heel, allowing for a snug fit to the foot. This completely prevents the heel from slipping or lifting off the insole. Essentially, because the upwardly curved heel support (150) holds the loose portion, the heel continues riding immediately without any delay or gap when the rear of the shoe is lifted with the lever. This feature significantly improves heel stability and enables the achievement of the intended goals (heel separation, no friction). It also provides greater stability by wrapping the heel more firmly. The upper curvature is designed to be gentle enough not to cause discomfort, functioning like an integrated heel counter that moves in conjunction with the lever plate. This system combines lever action with a physical heel cup to achieve both mechanical lift and consistent contact.

[0037] For the lever mechanism to operate, the forefoot portion of the sole must be able to move slightly when weight is applied. This controlled movement is made possible by designing a clearance portion (160) below the front portion (120) of the lever plate. That is, instead of the forefoot portion of the sole being completely filled with a rigid material or fixed in place, a gap or highly compressible area is formed just below the front portion of the lever plate. When the wearer's weight is transferred to the forefoot, the lever plate may sag slightly downward into this space. This downward displacement generates a force that lifts the lever upward from the heel as it rotates around the pivot point.

[0038] The clearance space (160), which functions as a clearance space, can be implemented in several ways. One method is to leave a void space in the lower sole (220) located below the front of the lever plate. Here, the lower sole (220) can be a midsole or an outsole. For example, the outsole and the bottom of the midsole in that area can be shaved down or designed as a void space. Another approach is to fill the space with a soft, highly compressible cushioning material. A cushioning material such as sponge foam or an air pocket can be used in this space (160). The key is that this cushion pad deforms much better than the surrounding sole material, effectively acting as a shock absorber or spring under the forefoot. The mechanism of the clearance space is as follows: Under normal weight, the forefoot lever presses the cushion (or void space) to compress the cushion. This allows the lever to rotate around a pivot point. The resistance of the cushion is adjusted to provide sufficient support while allowing for the necessary movement with just enough reaction force. The cushioning is more compressed than the midsole or outsole, allowing the forefoot lever to actually move (rather than the entire sole simply resisting). This movement stores energy in the compressed material and the lever. When weight is released, such as when lifting the foot, the cushioning expands to help the lever return to its original position. In effect, the cushioning space creates a controlled deformation zone for the lever's movement.

[0039] The selection of material for this cushion insert is critical. It must have lower stiffness (modulus of elasticity) and higher resilience (recovery) compared to standard midsole foam. For example, while typical outsole rubber is quite stiff and midsole EVA foam has moderate stiffness, the cushion can utilize softer PU foam or silicone air bladders that compress more easily under the same load. This invention recommends using materials with high shock absorption and rapid recovery; in particular, it is desirable for the cushion to be durable while effectively dispersing or absorbing impact energy. Examples include soft polyurethane sponges, gel inserts, or encapsulated air pockets (air cell units). These products deform significantly under load and then rebound to prepare for the next step. Conversely, if the forefoot is firmly attached to a hard outsole, the travel distance of the lever is severely limited, preventing the accumulation of sufficient force to effectively lift the heel. Furthermore, a rigid attachment can cause the forefoot lever to be pushed against an immobile floor, neutralizing the lever's action. Therefore, an air gap or soft pad under the forefoot is important. This is because when the front paw presses the lever, it moves the lever to secure space for "charging."

[0040] Meanwhile, the lever plate (100) according to the present invention may be provided with a cushion member pre-installed therein, which can be placed in the clearance space (160) on the bottom surface of the front portion (120). It is also possible to prepare the lever plate (100) with the cushion member pre-attached to the front portion (120), and then manufacture the prepared lever plate (100) by insert injection molding inside the midsole.

[0041] In summary, the clearance (160) allows the front arm of the lever to move freely, and the cushion placed within that space provides damping and energy return. This cushion softens the sensation under the forefoot (preventing a rough floor sensation when moving the lever) and absorbs shock to provide comfort. In particular, it can be used for two purposes: reinforcing the user's forefoot cushion to activate the lever mechanism while simultaneously reducing the impact applied to the sole of the foot. When manufacturing, it is preferable for the cushion material to be softer and more elastic than the preferred outsole and midsole materials (outsole is vulcanized rubber, midsole is EVA / TPU foam). Selecting such a material allows the forefoot lever to be easily pressed, and the lever mechanism to respond. After compression, the cushion quickly rebounds, allowing the lever plate to reset and prepare for the next step. Overall, this spacing and cushion arrangement resemble a small suspension system of the lever, which compresses and springs back when under load, allowing the system to circulate smoothly.

[0042] Several structural improvements may be applied to enhance the mechanical performance and durability of the lever system. The lever plate (100) may include grooves or ribs designed to increase bending stiffness along its length. In particular, as a method to increase the resistance to bending of the plate, grooves (131) and / or ribs (131a) may be formed longitudinally along the direction from the pulcrum portion (110) to the rear portion (130). By forming grooves (essentially channels or grooves) in the plate, the cross-sectional shape is changed, and the bending moment of inertia increases in that direction. Simply put, adding ribs (131a) or grooves (131) allows a thin plate to act as if it were thick, thereby reducing the degree of bending when subjected to a load. This is useful for ensuring that the lever plate remains sufficiently rigid when lifting the heel. Simulation and analysis of these grooves show that they can actually significantly reduce bending deformation. For example, using an optimal groove design improves the bending resistance of a lever plate by approximately 1.4 times compared to a flat plate, resulting in significantly less bending under the same load. However, analysis also reveals the pros and cons that if the groove is too deep, the material cross-sectional area is reduced and stress concentration occurs, which can weaken the plate. In this design, the best balance as the optimal groove depth can be provided when the groove depth (D) relative to the plate thickness (T) is in the range of approximately 15% to 30%. Below approximately 15% of the thickness, the improvement in bending resistance is reduced, and above approximately 30% of the thickness, structural stability drops sharply (risk of the plate buckling or cracking under stress). Therefore, the proposed range of D / T ratios can significantly increase bending resistance thanks to the improved effective moment of inertia, while simultaneously minimizing the risk of stress concentration and buckling caused by the reduction in cross-sectional area. In addition, the cross-sectional shape of the groove (131) and rib (131a) is rounded rather than being sharply cut.Rounded (curved) profiles can avoid sharp edges that cause stress concentration and fatigue cracks. Shallow, rounded grooves are particularly desirable when using metal for the plate, as they provide stiffness gains while minimizing potential crack initiation points. For composite or plastic plates, rounded or sharp grooves may be permissible due to manufacturing constraints, but soft radii are preferred for durability, helping the lever plate maintain its shape and effectiveness over time.

[0043] As mentioned in the description of the rear section (130), the rear portion of the lever plate is secured to the midsole and / or outsole of the shoe. This securing is crucial for stability, ensuring that the lever operates in a predictable single-degree-of-freedom manner (rotating from the pivot point). Secure securing prevents slippage or independent movement of the plate, which could reduce efficiency. Additionally, the plate is bonded to the shoe structure at the heel section to distribute force by utilizing the rigidity of the midsole / outsole. When the heel is lifted by the lever, the load is not borne solely by the plate, but is shared by the shoe's outsole and midsole. Consequently, the stress applied to the plate is reduced. The heel cup-upturn structure (150) at the rear of the plate not only physically cups the heel to hold the foot in place but also contributes to stability by adding a vertical rigidity element to the rear of the plate (acting like a flange to prevent the plate from twisting or deforming sideways). As a result, a more robust shoe capable of withstanding repeated impacts can be manufactured.

[0044] To maintain mechanical stability, the thickness and material selection of the lever plate are coordinated. The use of curved shapes and grooves in FIGS. 4 through 6 is intended to ensure that the thin plate operates rigidly without breaking. When using composite materials such as carbon fiber, a similar effect can be achieved by molding the plate into a form with embedded curvature and grooves. For example, carbon fibers can be stacked to add stiffness in a specific direction. The overall goal is to create a lightweight yet strong lever capable of withstanding the high cyclic loads of walking / running without significantly increasing the weight or volume of the shoe. The bending resistance and fatigue life of the lever plate can be improved by optimizing the geometry (smooth curves, grooves) and incorporating local reinforcements (lever bumps, heel cups).

[0045] The shoe system according to the present invention applies a special lever mechanism to the sole to maintain heel contact and absorb shock. The shoe may be composed of a semi-rigid lever plate embedded inside or on top of the midsole, a strategically placed support structure, and a clearance space capable of controlling movement. Furthermore, the proposed components, ranging from a curved lever structure to a compressible forefoot pad and plate reinforcement structure, can increase the effect of the invention by reducing the accumulation of heat and shock on the heel and providing comfortable fixation when the user walks or runs.

[0046] In addition, a shoe including a lever plate according to the present invention can provide various performance and comfort advantages.

[0047] First of all, heat accumulation due to friction and impact can be significantly reduced. By preventing the heel from separating and striking the insole again, friction that generates heat inside the shoe is drastically reduced. Since the heel remains in contact, heat is not generated due to repetitive friction. Consequently, heat accumulation over a long period is minimized, keeping the feet cooler and drier. Reduced heat and sweat in the heel improve comfort during prolonged exercise. Runners and walkers wearing the shoes according to the present invention experience less of the hot and damp sensation often associated with conventional shoes. Furthermore, because the lever mechanism according to the present invention disperses impact force from the forefoot to the heel rather than concentrating it as friction on the heel, there is a lower likelihood of blisters or heat spots forming on the heel skin.

[0048] Furthermore, the lever system applied in this invention optimizes the way force is transmitted through the shoe during walking. When the forefoot is pressed, the force is not completely lost or absorbed by foam deformation, but is partially redistributed to help lift the heel. As a result, the shoe effectively assists the natural movement of the foot, increasing energy efficiency. This system utilizes the wearer's body weight and movement to provide a light propulsion effect that helps push the foot upward when the lever returns to its original position. Since the heel does not receive a hard impact after the load is applied to the forefoot and descends smoothly by the guide, the overall gait becomes smooth. This prevents energy loss caused by uncontrolled shoe deformation or slipping, thereby reducing the metabolic cost for the runner. Essentially, the shoe takes over some of the work that the foot and leg muscles would otherwise have to do. While the lever system applied to the shoe according to this invention is primarily for comfort, it also enables the wearer to maintain performance with slightly less effort. By stabilizing the foot and reducing unnecessary movement, it can reduce tension in the calf and shin muscles during long-distance running. Efficient power transfer means that the shoe utilizes ground reaction force in a productive way, rather than wasting it as heat and vibration.

[0049] Furthermore, the mechanical stability of the shoe is enhanced through the reinforcement and shock absorption of the lever plate. Smooth force distribution and additional structural elements (such as knobs and grooves) contribute to increased outsole durability. For instance, curved lever plates avoid sharp bending points, and rounded grooves disperse stress, minimizing stress concentration to reduce the likelihood of material fatigue or failure over time. The outsole and midsole also mitigate general wear caused by repetitive heel impact and stress on the forefoot, as the lever plate transmits force in a controlled manner. In particular, the heel receives less indiscriminate impact because the lever partially absorbs force and redirects it. This results in less foam compression and more even pressure distribution across the outsole, which can lead to a longer shoe lifespan and sustained cushioning performance. Additionally, a rigid heel cup and plate add stiffness to prevent deformation. In summary, the design focuses on mechanical leverage and support, offering high resilience even during prolonged use, and is expected to maintain its protective function for a longer period than conventional shoes.

[0050] In addition to heat reduction, wearers feel more stable and supported when wearing the shoes. The Dynamic Heel Lift mechanism firmly secures the heel without the need to overtighten the laces. This means the shoes can be worn in the proper position—neither too loose nor too tight—and the heel does not slip. By eliminating heel slippage and providing gentle upward pressure from the heel cup, stability can be enhanced when walking on inclines or running. Essentially, this system maintains key contact points and customizes the shoe to fit the foot during movement. This can boost the user's confidence in their feet and reduce the occurrence of friction blisters. Furthermore, since the laces do not need to be tightened too much, overall foot circulation is improved, and the breathability of the upper is enhanced. Therefore, the indirect benefits of comfort include potentially being cooler and drier, with reduced lace pressure on the instep.

[0051] The footwear according to the present invention can be further refined or adjusted to suit various use cases. For example, the material for the lever plate can be explored, such as using spring-grade alloys to reduce weight while offering excellent fatigue life, or using advanced composite materials to create customized flex patterns. Each material can be balanced to suit the target activity by considering the pros and cons of weight, stiffness, and cost (e.g., carbon fiber plates for elite running shoes focused on light weight, or steel plates for work boots focused on durability). The cushioning pads in the forefoot can also be custom-made, and fluid or gel-based pads can be used to provide much more effective heat dissipation and shock absorption compared to foam. The volume and shape of the clearance can be adjusted. Larger or softer pads provide more movement and a softer feel, whereas smaller or firmer pads may result in stiffer responsiveness. Designers can adjust this to suit the preferences of various runners (e.g., enhanced cushioning versus enhanced responsiveness). Furthermore, the concept can be extended with multiple pulcrum sections or segmented levers to enable more nuanced control (separate lever elements can be added to the medial and lateral sides of the foot to distribute uneven pressure). Ventilation channels or vents can be integrated into the rear section to further mitigate residual heat and complement friction reduction strategies. Since the primary goal is to minimize heat, one might consider using thermally conductive inserts that diffuse and dissipate heat from the heel area, or moisture-absorbing linings that help keep the heel dry. Finally, the system's aesthetics and weight can be optimized by trimming unnecessary materials, using lightweight foam, and elegantly integrating lever plates into the shoe's silhouette. Through these improvements, the shoe system can remain practical while maintaining competitiveness against existing designs.It is robust overall, and through careful material selection and parameter adjustments, comfort, heat reduction, and efficient biomechanics can be improved to suit various footwear categories (running shoes, hiking boots, etc.).

[0052] Although preferred embodiments of the present invention have been described so far, those skilled in the art may implement the invention in modified forms without departing from the essential characteristics of the invention. Therefore, the embodiments of the present invention described herein should be considered in an illustrative rather than a restrictive sense, and the scope of the present invention is defined by the claims rather than the description above, and should be understood to include all modifications, equivalents, and substitutions that fall within the spirit and technical scope of the present invention.

Claims

Claim 1 A lever plate positioned between the upper sole and the lower sole of a shoe, characterized by comprising: a pulcrum portion formed along a transverse arch formed at the bottom of the human foot; a front portion positioned at the forefoot and extending upwardly inclined from the pulcrum portion; and a rear portion extending from the pulcrum portion to the rearfoot portion. Claim 2 A lever plate according to claim 1, characterized in that at least a portion of the bottom surface of the front portion extending from the pulcrum portion is formed as a curved surface. Claim 3 A shoe characterized by having a heel support formed by bending upward at the end of the rear portion.

Images