ES3009478T3 - Swimming fin - Google Patents

Abstract

The invention relates to a swimming fin with a foot piece (1, 3, 4) that is fixed to the swimmer's foot and a blade (2) that is fixed to said piece. The blade (2) comprises an elongated support (5) and at least two aerodynamic blades (7, 7i, 8, 8i) that protrude from the side of the support (5) and are arranged to rotate through a predefined angle in both directions. According to the first object of the invention, the fin is distinguished by the movable arrangement of the elongated support (5) with respect to the foot piece (1, 3, 4) that is fixed to the swimmer's foot. According to a second alternative or additional object of the invention, the swimming fin is distinguished in that the aerodynamic blades (7, 7i, 8, 8i) protruding on opposite sides with respect to the longitudinal axis (9) of the support (5) are connected by a flat crossbar (46) extending through a hole (45, 45i) in the elongated support (5), while the hole (45, 45i) in the elongated support (5) is provided with blade movement limiters (47, 48) in the form of protrusions and is larger than the crossbar (46) passing through it. (Automatic translation with Google Translate, no legal value)

Description

DESCRIPTION

Swimming fin

The invention relates to aids for swimming, underwater movement and muscle training, and can be used in the construction of a swimming fin that is attached to the foot.

According to document FR 2931690 A1, a swimming fin is known with a foot portion that is attached to the swimmer's foot and a fin blade attached to the tip of the foot portion. The fin blade has an elongated support and at least two aerodynamic blades. The blades are rotatably mounted on both sides of the elongated support, around pivot axes that transversely cross a longitudinal axis of the elongated support, and can be rotated back and forth in both directions within a predetermined angle. The blades are mounted on the elongated support via a common axis. The foot portion, which is attached to the swimmer's foot, includes a reinforced sole to which the elongated support of the swimming fin blade is connected. The longitudinal axis of the elongated support is inclined with respect to the sole of the foot portion at an angle of 12°. During the kicking motion, the elongated support rotates and/or flexes relative to the foot section that attaches to the swimmer's foot. The material of the elongated support is rigid enough to avoid excessive deformation under bending or twisting.

According to WO 2010/140965 A1, a swimming fin is known with a foot portion including a toe section and a fin blade fixed to this portion. The fin blade consists of an elongated support and at least one aerodynamic blade extending transversely to the longitudinal axis of the elongated support. This blade is rotatably mounted on both sides of the elongated support, around a pivot axis transverse to its longitudinal axis, and can oscillate back and forth within a predetermined angle in both directions. The elongated support is rigidly fixed to the toe section at an angle between 20° and 60° with respect to the longitudinal axis of the sole of the foot portion. The blade may be hollow for filling with water during diving. The tips of the blades, also known as side edges, may be delimited by vertical wall sections. Furthermore, the elongated support may be arranged inclined, deviating from the longitudinal axis of the foot portion.

The closest technical solution is found in the swimming fin described in FR 2 931 690 A1. This fin includes a shoe connected to one or more blade systems. The blade system consists of an elongated support with a cylindrical hole passing through the support perpendicular to its longitudinal axis. It also includes a propulsion element consisting of two aerodynamic blades mounted on a common axis, with their lateral surfaces fixed on both sides of the axis. The leading edge of the blades is parallel to the axis, which is rotatably mounted in the hole in the support.

For the sake of clarity, it should be noted that the terms "angle of attack", "leading edge", "airfoil chord" and "blade" are taken from aerodynamics.

The use of the aforementioned swimming fin is based on the swimmer's leg-swimming movements in the water. During this process, the blades rotate freely relative to their axis until they reach their limit stop at the spin limiter. The blades then push through the water, transferring the reaction force to the swimmer. Although, according to the description, the angle of rotation of the blades is automatically adjusted based on the swimmer's movement speed, no effective system for automatic adjustment is provided.

The description includes a fin design that features blade rotation limiters. These are connected to a bar that can be moved within the bracket. At one end, the bar has a thread onto which a knurled knob is screwed for adjustment. It also mentions that the swimmer must manually turn this knob, located at the end of the bracket, to adjust the pitch angle of the blades. This adjustment modifies the angle of the blades relative to the bracket.

Each time the swimmer wishes to perform this adjustment, they must interrupt their movement in the water and stop. It is also important to note that this procedure is not comfortable to perform without removing the fin from their foot. In the description of the aforementioned technical solution, it is stated several times that the support must be rigid to prevent deformation during use of the swim fin. A rigid and stable support is also considered necessary to prevent jamming of the device that regulates the angle of attack of the blades. The description also specifies that the support is tilted approximately 10 degrees relative to the sole of the foot. This support design significantly hinders entry into the water from dry land with the fins already in place.

All of the patents mentioned claim that the use of multiple blades, mounted on one or two longitudinal bars (supports), increases the efficiency of the swimming fin.

The efficiency of the swimming fin was evaluated on a dynamometer test bench. The basic layout of the test bench is shown in Figure 12. The procedure for evaluating the fins' efficiency was as follows: - The swimming fin to be tested was placed on the lower horizontal bar of the test bench. - The bench actuation generated up-and-down kicking movements of the horizontal bar at a constant frequency.

- Throughout the test cycle, the angle of rotation of the horizontal bar, the force required to operate the bench, and the reaction force (impulse) were measured.

- The efficiency of the swimming fin was calculated and graphs were drawn up.

Comparative tests carried out in a swimming pool using the dynamometric test bench showed that the swimming fin, designed according to French patent No. 2931690, has a slightly higher efficiency compared to the current classic fin (of the AQUALUNG trademark).

There are two main reasons for its insufficient efficiency:

- 1. Classic swimming fins are now manufactured using high-quality modern materials and new technologies, which gives them good efficiency.

- 2. The dynamics of a swimming fin with multiple blades, mounted on one or two longitudinal bars (supports), is imperfect, as shown in Figure 10. This figure illustrates that the angle of incidence of the blade is small in the initial phase of the fin's stroke. At this stage, the water current G exerts little or no resistance on the blade. As the stroke progresses, the resistance against the water current progressively increases. The reaction force reaches its maximum at the moment the fin crosses the bisector line of the stroke angle. However, after this point, the reaction force begins to decrease, while the blade's resistance against the water current abruptly increases. These changes in forces during the fin's stroke are most clearly illustrated by the example of a blade in Figure 11.

During a swing, water pressure P acts on the surface of the paddle, generating a force Q, which is directly proportional to the product of this pressure and the projection of the paddle's area. The formula is:

Q=k-P-S-sin a

where:

k: is a constant coefficient for a given flow rate.

Q: It's the water pressure.

S: is the area of the blade.

a: is the angle of incidence of the blade.

The force Q is directed perpendicular to the plane of the blade. This force generates a reaction force R, which acts forward in the direction of the axis of motion. The reaction force R is calculated using the formula:

R=Q-cos a

During the fin's stroke, the fins must overcome the water's resistance to flow. The resistance force is calculated using the formula:

F=CW'Q

where:

Cw: is the coefficient of resistance to flow.

Q: is the force generated by the pressure of the water on the blade.

In this case, the blade can be considered as a flat plate, where Cw=1. Therefore, it can be assumed that F=Q. The force applied to the fin to overcome the flow resistance F corresponds to the energy effort that is converted into reaction force R. The efficiency n of the blade (or blades) is calculated as:

n=R/Q

Figure 11 illustrates three schemes (a, b, c) showing that the maximum efficiency of the blade is reached in the initial phase of the fin's beating motion. In the middle phase of the motion (scheme b), the reaction force R reaches its maximum value, but the efficiency decreases. In the later phases, the reaction force R decreases, while the drag force increases rapidly, leading to a significant reduction in the blade's efficiency.

Simple calculations show:

In the case of scheme "a", the efficiency n is 0.88.

In scheme "b", n is 0.64.

In scheme "c", n is 0.34.

The overall low efficiency of a multi-bladed swim fin is due to a sharp decrease in efficiency after the fin passes the stroke angle bisector. The above results are based on ideal efficiency calculations. However, actual performance will always be lower than ideal due to practical factors.

All this shows that the efficiency of the fin described in document FR 2931690 A1 cannot be implemented satisfactorily, which represents the technical problem of the prototype construction discussed here.

Another technical problem common to all the aforementioned fins is the attachment of the blades to the longitudinal arms, also called supports. Solutions for connecting the blades to the supports can be classified into four types:

- Use of an axle: The axle passes through the body of the support or is fixed to one side of the support (references: FR 2 931690 A1; WO 2010/140965 A1; US 3,084,355; US 3,081,467).

- Elastic hinge: Generally made of an elastic material such as rubber (references: DE 202007 004633 U1; US 2012/0115377 A1).

- Rigid fixation: The functionality is based on the elasticity of the blade material (references: FR 2929 127 A1; WO 94/25116 A1; WO 2017/175151 A1).

- Combined method: Uses an axle, an elastic hinge and internal stops (reference: US 4,944,703).

When the blades are attached to the support by means of shafts, the problem of the fin's "empty motion" becomes evident. This occurs when the swimmer performs a kicking motion without generating effective propulsion. The causes of this phenomenon are as follows:

During the reversal of the fin's stroke, the blades must rotate to shift into an opposite position that allows them to push through the water. To achieve this, the fin must initiate the stroke from a "standstill" before the blades can begin generating thrust. At the beginning of the stroke, the blades first rotate to a position where they can begin pushing through the water. Only after this preliminary stage does the fin's effective stroke begin. In the initial phase of the fin's stroke, the so-called "empty stroke" occurs, resulting in a significant decrease in the fin's efficiency.

Tests have shown that the "empty motion" problem is more pronounced the larger the blade dimensions.

Reducing the size of the blades helps mitigate the problem, but does not completely solve it. Connecting the blades to the support using elastic hinges allows the blades to return to a neutral position at the end of a stroke. This reduces the "empty motion" by half and makes the problem less severe. However, finding a balance between the elasticity of the hinge material and its mobility is difficult. This implies that: If the hinge material can overcome the mass of the water when returning the blade to the neutral position, then it restricts the blade's ability to turn at significant angles during the stroke. Elastic hinges are difficult to adjust and limit blade twist to a maximum of 30 degrees.

Elastic materials such as rubber and thermoplastic elastomers are known to rapidly lose their properties when exposed to UV light. This limits their long-term use in outdoor applications.

When the blades are rigidly attached to the support, and their functionality depends on the elasticity of the blade material itself, the problems persist. Material elasticity alone does not effectively resolve the "vacuum motion."

The method combining elastic shafts and hinges, as described in US Patent 4,944,703, adds complexity to the design without fully solving the problems. Furthermore, this connection of the blades to the support presents a high risk of clogging by sand and algae, further reducing the fin's efficiency and durability.

The technical problems described above are solved by a swimming fin with the characteristics described in claim 1.

The swimmer's foot attachment element typically includes a reinforced sole, to which the elongated fin blade support is connected. This elongated support is hingedly connected to the reinforcement of the sole of the swimmer's foot attachment element. The hinge may be equipped with at least one return spring. The support may be designed to be elastically deformable or rigid.

The elongated support can also be designed to be elastically deformable and, at the same time, rigidly connected to the reinforcement of the sole of the fixing element.

The elongated support may contain internal cavities that may be closed or communicate with the external environment to allow water entry.

The longitudinal axis of the elongated support is oriented forward from the attachment element to the swimmer's foot. This axis is preferably positioned at an angle between 0° and 20° relative to the longitudinal axis of the support.

The blades are usually mounted on the elongated support by means of a common axis.

In another configuration, the blades arranged on opposite sides of the support are connected to each other by a crossbar that passes through an opening in the elongated support.

The opening in the elongated support is larger than the crossbar that runs through it.

The opening is not round in shape and, inside, there are stops that limit the rotational movements of the crossbar around the rotation axes of the respective blades.

The surface of the opening may be covered with a material designed to cushion contact between the stops and the crossbar. Figure 15 shows possible shapes of openings in the elongated support. These openings may also have other shapes depending on the design of the elongated support.

The elongated fin blade support may be composed, at least partially, of aerodynamic blade modules.

The elongated support is equipped, at least on one side, with a protrusion intended to limit the rotation of the aerodynamic blade.

The technical result of this invention is the increase in the operating efficiency of the swimming fin.

The proposed swimming fin is schematically represented in the following figures:

Figure 1: Axonometric representation of the swimming fin.

Figure 2: Exploded view of the swimming fin in axonometric representation.

Figure 3: Side view of the swimming fin, showing a joint connecting the sole reinforcement to the elongated support.

Figure 4: Functional phases of the swimming fin during the downstroke movement.

Figure 5a, 5b: Schematic representation of the fin operation during upward and downward movements.

Figure 6: Aerodynamic blade.

Figure 7a: Side view of a swimming fin with a rigid connection between the sole reinforcement and the elongated support. Figures 7b, 7c: Schematic representation of the swimming fin's operation with an elastically deformable elongated support during the upward movement. Figure 8: Proposed swimming fin with a blade in a modular configuration.

Figure 9: Swim fin with detachable design.

Figure 10: Functional phases of a swimming fin prototype based on French patent no. 2931690 during the downward movement.

Figure 11: Schematic representation of the forces acting on the blades of the swimming fin prototype of French patent no. 2931690 in different phases of the downward movement.

Figure 12: Schematic of the operating principle of the dynamometric test bench for swimming fins.

Figure 13: Position of the elongated support planes.

Figure 14: Exploded view of the swimming fin with blades mounted by crossbars.

Figure 15: Design variants of the openings in the elongated support.

Figure 16: Connection between "Crossbar and Blade".

Figure 17: Design examples in 17a, 17b and 17c of structural elements of the elongated support.

Reference numbers in Figures 1 to 17:

1 - Piece to attach to the swimmer's foot.

2 - Fin blade.

3 - Piece to attach to the swimmer's foot, designed in the shape of a shoe.

4 - Piece to attach to the swimmer's foot, designed in the shape of a bag with adjustable straps.

5 - Elongated support.

6 - Tip of the foot piece.

7 to 7i, 8 to 8i - Aerodynamic blades.

9 - Longitudinal axis of the elongated support.

10 - Longitudinal axis of the piece to be fixed to the swimmer's foot.

11 - Aerodynamic blade module.

12 to 12i - Drilling in the elongated support.

13 to 13i - Common rotating connection axis of the aerodynamic blades.

14 - Symmetry plane of the blade.

15 - Upward movement of the swimmer's leg.

16 - Downward movement of the swimmer's leg.

17 - Leading edge of an aerodynamic blade.

18 - Trailing edge of an aerodynamic blade.

19 - Axis of rotation of an aerodynamic blade.

20 - Lateral edges of an aerodynamic blade.

21 - Aerodynamic surface of the blade, blade blade.

22 - Length (chord of the profile) of an aerodynamic blade.

23 - Width of an aerodynamic blade.

24 - Continuous openings for water flow.

25 to 25i - Projections on the elongated support that act as rotation limiters for the aerodynamic blades.

26 - Sole reinforcement, foot reinforcement.

27 - Joint.

28 - Fork.

29 - Articulation axis.

30 - Return spring.

31 - Stabilizer.

32 - Connection.

33 - Swimming fin propulsion.

34 - Fin stroke angle sensor.

35 - Dynamometer.

36 - Horizontal bar.

37 - Vertical bar.

38 - Swimming fin to test.

39 - Pull-up bar.

40 - Structure of the test bench.

41 - Control unit.

42 - Data logger.

43 - Vertical plane.

44 - Horizontal plane.

45, 45i - Hole or opening in the elongated support.

46 - Sleeper.

47 - Sleeper movement limiter.

48 - Sleeper movement limiter.

49 - Rib.

50 - Opening.

51 - Internal cavity.

52 - Joint cover.

a - Angle of attack of the blade.

131, 32t, 133 ... I3¡ - Angles between the plane of symmetry of the blade and the longitudinal axis of the elongated support in rigid configuration, which are generated during an upward movement of the fin.

Yl,<y>2<í>,<y>3 ■■■ Y¡ - Angles between the plane of symmetry of the blade and the longitudinal axis of the elongated support in rigid configuration, which are generated during a downward movement of the fin. $ - Angular deviation of the axis of the elongated support with respect to the bisector of the angle of stroke of the fin.

The fin consists of: a swimmer's foot attachment (1), and a fin blade (2) attached to the foot attachment (1).

The fixing foot 1 is preferably made of rubber and/or thermoplastic elastomer and designed in the form of a shoe (3, Figure 1). However, other configurations are possible, such as a bag or partial slipper (4) with several adjustable straps (Figure 2).

The attachment foot 1 includes a rigid sole and may contain a sole reinforcement (26) for added rigidity. This reinforcement may be manufactured as an integral part of the shoe (3) using a polymer, or other materials such as metal, carbon and/or other fiber-reinforced polymers, laminated wood, fiberglass, etc.

The sole reinforcement (26) may be attached to the sole of the fixing foot (1) by means of rivets, screws, adhesives or welding, or even injected directly into the body of the sole. The front part of the fixing foot (1) includes a fork (28) designed to connect to the elongated support (5).

The fin blade 2 comprises an elongated support (5) directed forward from the tip (6) of the attachment foot (1) and at least two aerodynamic blades (7 and 8). The longitudinal axis (9) of the elongated support (5) extends along its longitudinal direction and is preferably parallel to the longitudinal axis (10) of the shoe (3). However, it may also be inclined up to 20° with respect to the longitudinal axis (10) of the shoe (3).

The elongated support 5 is connected to the foot 1 by a joint 27 (Figure 3).

The hinge 27 includes a fork-shaped component 28, which may be integrated with both the elongated support 5 and the foot 1. The hinge also comprises the hinge-opposite part 27 and an axis 29. This hinge allows the elongated support 5 to rotate relative to the foot 1. As a result, the longitudinal axis 9 of the elongated support 5 may change its position relative to the longitudinal axis 10 of the foot 1.

The joint 27 is equipped with at least one return spring 30. This spring 30, either by itself or as part of a spring device, returns the elongated support 5 to its initial position after the leg movement ends. The characteristics of the spring 30 or the spring device are adjusted to maximize the effectiveness of the force applied by the swimmer. Such characteristics can be either linear or non-linear. The elongated support 5 is designed to be rigid (Figures 3 and 4), but can also be flexible and deformable (Figures 7a, 7b and 7c).

The elongated support 5 may incorporate internal spaces 51, external ribs 49 and openings 50 of various shapes. The internal spaces 51 may be closed or connected to the external environment, allowing water to enter. The combined use of ribs, openings and internal spaces favors the regulation of the elastic deformation of the elongated support both in the vertical plane 43 and in the horizontal plane 44 (see Figure 13 and Figure 17). A flexible and deformable elongated support 5 may also be rigidly connected to the foot 1, for example, by means of a coupling piece 32.

During the kicking motion of the legs, the longitudinal axis 9 of the elongated support 5, together with the support 5, bends relative to the longitudinal axis 10 of the foot 1 due to the elastic deformation of the support 5 itself and/or due to a thin section present in the elongated support 5.

The elongated support 5 is generally manufactured as a single piece, although it may be composed, at least in part, of several modules 11 of aerodynamic fins 7i and 8i (Figure 8).

The elongated support 5 has at least one stabilizer 31 in the form of an extension at the end of the support, arranged in a plane perpendicular to the axis of rotation 19 of the aerodynamic fins 7 - 7i and 8 - 8i.

The elongated support 5 may be made of materials such as metal, polymers reinforced with carbon fibers and/or other fibers, plywood, fiberglass reinforced plastic, among others. The aerodynamic fins 7 and 8 are mounted in an articulated manner on the elongated support 5, on both sides, on a common rotating connection axis 13. This axis is placed in the hole 12, generally allowing the aerodynamic fins 7 and 8 to rotate together with their connection axis 13 in both directions with respect to the aforementioned elongated support 5, within a predetermined angle.

Typically, turning in one direction is possible up to an angle pi between the longitudinal axis 9 of the elongated support 5, extending along its length, and the plane of symmetry 14 of the i-th aerodynamic fin 7 or 8 during an upward movement 15 of the swimmer's leg. Turning in the opposite direction is possible up to an angle yi between the aforementioned axis 9 and the plane 14 during a downward movement 16 of the swimmer's leg.

The plane of symmetry 14 of the i-th aerodynamic fin 7 and 8 passes through the front edge 17 of the fin 7 and 8, their rear edge 18 and the axis of rotation 19 of the fins 7 and 8. The rotation angles pi and yi of the fins 7 - 7i and 8 - 8i may vary depending on whether the fins are closer to the foot 1 or at the opposite end of the support 5 within the blade of the fin 2.

As a special case, the aerodynamic fins 7 and 8 can be detachable from the elongated support 5. The design of the aerodynamic fins 7 or 8 is preferably trapezoidal with rounded corners, although they can also have other shapes. Each of the aerodynamic fins 7 or 8 has a leading edge 17 facing the foot piece 1, a trailing edge 18, two side edges 20 and two aerodynamic surfaces 21 between them (Figure 6). A common rotating connection shaft 13 is inserted into each aerodynamic fin 7 and 8, positioned in the first third of the length 22 (profile chord) of the fin 7 or 8 on the side of the leading edge 17.

The leading edge 17 of the fin may be curved and/or straight, but is positioned at an angle to the axis of rotation 19 of the fin 7 or 8. The leading edge 17 may also be designed as a broken straight line.

The aerodynamic fins 7 or 8 on one side of the elongated support 5 may have the same or different dimensions compared to the aerodynamic fins 8 or 7 located on the other side of the elongated support 5, either in terms of their length 22 and/or width 23. The fins 7 and 8 may be provided with through openings 24 to allow water flow and reduce the pressure on the fins 7 and 8.

A common pivoting shaft 13 for connecting the aerodynamic fins 7 or 8 can also serve to increase the rigidity of these fins. In this case, the aforementioned shaft 13 is inserted deeply into the fin 7 or 8.

The fin blade 2 is generally equipped with two or more pairs of aerodynamic blades 7 - 7i and 8 - 8i. The dimensions of each pair of aerodynamic blades are preferably the same, although they can also be different. This applies both to all pairs of blades and to only one or more pairs. The aerodynamic blades 7 or 8 are preferably designed to be rigid, maintaining their shape under the influence of water flow. However, they can also be elastic, flexible in the longitudinal and/or transverse direction relative to the longitudinal axis 9 of the elongated support 5 on its long side.

The fin blade 2 has a rotation limiter for the airfoil blades 7 or 8, which restricts their rotation within a predetermined angle. This limiter may be integrated with the common rotation axis 13 connecting the blades. The limiter may be formed as at least one projection 25. It is arranged on the elongated support 5 so as to allow contact with the projection of at least one of the airfoil blades 7 or 8 in its final rotation position (Figure 5a, 5b). The projection 25 of the elongated support 5 is preferably cylindrical and is positioned on the lateral surface of the elongated support, although it may also have another shape. Generally, each pair of airfoil blades 7 - 7i and 8 - 8i has an associated projection 25 - 25i.

The limiting projections 25 may be designed on opposite side surfaces of the elongated support 5 for each airfoil 7 or 8, or at least one projection 25 may be on opposite sides relative to the axis of rotation 19 of the airfoils 7 or 8. The projections 25 may be integrated into the elongated support 5 or added as separate parts.

The projection 25 that limits the rotation of the blades 7 and 8 may be covered with a rubber material to cushion the contact between the blades 7 or 8 and the projection 25.

For this purpose, other materials with contact-damping properties can also be used. The projection 25 itself on the elongated support 5 can be made entirely of a material that ensures damping and/or softer contact between the blades 7 or 8 and the limiting projection 25.

As a design variant, the blades 7 - 7i or 8 - 8i can be fixed to the elongated support 5 by means of a loose joint (Figures 14 and 15). In this case, the blades 7 - 7i or 8 - 8i are connected to one another by means of a flat cross member 46, which passes through an existing opening in the elongated support 5, such as a hole 45 or 45i. The opening 45 or 45i in the elongated support 5 is larger than the cross member 46 passing through it. Said opening is not round in shape. Within the opening 45 or 45i are located stops 47 and 48 which limit the rotational movement of the cross member 46 around the rotation axes 19, also called pivot axes, of the respective blades 7 - 7i or 8 - 8i. The surface of the opening 45 or 45i may be coated with a material that cushions the impact of the cross member 46 against the stops 47 and 48. This makes the recurring contact between the stops 47, 48 and the cross member 46 connected to the blades 7 - 7i or 8 - 8i during each fin stroke softer. Figure 15 shows possible shapes of the openings 45, 45i in the elongated support 5. The openings provided in the elongated support 5 may also have other shapes.

Due to the complexity of the manufacturing processes and the construction solutions, the stops 47 and 48, which limit the rotational movement of the sleepers 46, can also be located outside the free joint directly on the support 5.

The sleeper 46 is preferably positioned in the forward half of the blades 7 - 7i or 8 - 8i (Figure 16). The sleeper 46 is preferably flat, although it may also have other design shapes.

The free hinge may be provided laterally with covers 52 (Figure 14). The covers 52 form vertical partitions relative to the support 5 on the inner sides of the hydrodynamic surfaces 21 of the blades 7, 7i, 8, 8i, facing the support 5. The covers 52 may be formed of discs, include discs, or be surrounded by discs. These covers, formed for example of discs, advantageously tension planes on which the respective pivot or rotation axes 19 of the blades 7, 7i, 8, 8i are perpendicularly located. The covers 52 effectively prevent contamination of the openings 45, 45i, made for example as holes in the elongated support 5. For example, the covers 52 prevent the openings 45, 45i from becoming clogged with algae. The covers 52 may be embedded in the body of the support 5 or protrude outwards.

As a special case, the fin can be made of positively buoyant materials.

Fin operation: The swimmer performs up (15) and down (16) movements of the legs to move forward in the water, as shown in Figures 4, 5a, 5b and 7b.

During an upward movement (15), as illustrated in Figure 5a, the hydrodynamic blades 7 and 8 rotate under water pressure through an angle pi. Upon reaching their final position, the rotating blades 7 and 8 strike against the limiting projections 25 present on the elongated support 5. Subsequently, a push of the blades 7 and 8 against the water occurs, transferring the impulse force through the elongated support 5 and the swimmer's foot. As the movement of the fin continues, the water pressure on the fin blade 2 increases due to the increase in the angle of attack of the hydrodynamic blades 7 and 8. Under the increased pressure, the elongated support 5 overcomes the force of the spring 30.

The elongated support 5 overcomes the force of the spring 30 when the water pressure increases. It rotates at the joint 27, which connects it to the foot part 1. The rotation of the elongated support 5 reduces the angle of attack of the hydrodynamic blade, which decreases the resistance on the fin 2 and increases the thrust force. As the kicking motion with the fin continues and the water pressure on the fin 2 increases, the elongated support 5 rotates through a larger angle relative to the foot part 1. This further reduces the angle of attack of the blades 7 or 8, thus decreasing the resistance of the fin 2. When the kicking motion of the fin stops, the fin 2 returns to its initial position relative to the foot part 1 under the action of the spring 30 of the joint 27. This provides an additional boost to the swimmer.

Then, the hydrodynamic blades 7 or 8 rotate under the water pressure during the downward movement 16 of the fin (Figure 5b) at an angle <yí>. The rotating blades 7 and 8 strike against the limiting projections 25 present on the elongated support 5 upon reaching their final position. Subsequently, the blades 7 and 8 push the water, transmitting the thrust force through the elongated support 5 and the foot part 1 to the swimmer. As the downward movement of the fin continues, the water pressure on the fin 2 increases due to the increase in the angle of attack of the hydrodynamic blades 7 or 8. Under this increased pressure, the elongated support 5 rotates within the joint 27, which is connected to the foot part 1.

Rotation of the elongated support 5 reduces the angle of attack of the hydrodynamic blades 7 or 8, thereby decreasing the drag on the fin 2 and increasing the reaction force. As the fin's kicking motion continues and the water pressure on the fin 2 increases, the elongated support 5 rotates through an even greater angle relative to the foot portion 1. This further reduces the angle of attack of the blades 7 or 8, thereby decreasing the drag on the fin 2 and maximizing its effectiveness.

When the kicking motion of the fin stops, the fin 2 returns to its initial position relative to the foot part 1 thanks to the action of the spring 30 of the articulated mechanism 27. This provides the swimmer with an additional impulse.

In another fin configuration, incorporating an elastically deformable elongated support 5, this may be rigidly fixed to the foot portion 1 (Figures 7a, 7b and 7c). In this case, the hydrodynamic blades 7 and 8 rotate under water pressure during an upward movement 15 of the fin through an angle pi (similar to Figure 5a). The rotating blades 7 or 8 strike against the limiting projections 25 present on the elongated support 5 upon reaching their final position. Subsequently, the blades 7 and 8 push the water, transmitting the thrust force through the elongated support 5 and the foot portion 1 to the swimmer.

As the upward movement of the fin continues, the water pressure on the fin 2 increases due to the increase in the angle of attack of the hydrodynamic blades 7 or 8. Under this increased pressure, the elongated support 5 elastically deforms, and its longitudinal axis 9 curves relative to the root portion 1. This curvature reduces the angle of attack of the hydrodynamic blades, thus decreasing the drag of the fin 2 and increasing the reaction force.

As the kicking motion of the fin continues and the water pressure on the fin 2 increases, the elongated support 5 bends at an even greater angle relative to the foot portion 1. This further reduces the angle of attack of the blades 7 or 8, decreasing the drag on the fin 2 and increasing the thrust force. When the kicking motion of the fin stops, the elongated support 5 returns to its original, resilient shape, and the fin 2 returns to its initial position relative to the foot portion 1, thus providing additional thrust to the swimmer. During the downward stroke 16 of the fin, the hydrodynamic blades 7 and 8 rotate under the water pressure through an angle yi (similar to Figure 5b). The rotating blades 7 and 8 strike against the limiting projections 25 of the elongated support 5 upon reaching their final position. Subsequently, the blades 7 and 8 push the water, and the thrust force is transmitted through the elongated support 5 and the foot part 1 to the swimmer.

During the subsequent upward movement of the fin, the water pressure on the surface of the fin 2 increases due to the increased angle of attack of the hydrodynamic blades. Under this increasing pressure, the elongated support 5 elastically deforms, causing its longitudinal axis 9 to curve relative to the root portion 1. This curvature reduces the angle of attack of the hydrodynamic blades 7 or 8, thereby decreasing the drag of the fin 2 and increasing the reaction force.

As the kicking motion of the fin continues and the water pressure on the fin 2 continues to increase, the elongated support 5 elastically bends through an even greater angle relative to the foot portion 1. This further reduces the angle of attack of the blades 7 or 8, decreasing the drag on the fin 2 and increasing the thrust force. When the kicking motion of the fin stops, the elongated support 5 elastically springs back to its original shape, and the fin 2 returns to its initial position relative to the foot portion 1, providing additional momentum to the swimmer.

The elasticity of the elongated support 5 is greater in a vertical plane 43 (called "vertical plane") than in a horizontal plane 44 (called "horizontal plane"), which is perpendicular to the vertical plane 43 and which encompasses the hydrodynamic blades together with the longitudinal axis 9 of the support 5 (see Figure 13).

By elastically deforming the elongated support 5 in the vertical plane 43, the fin's efficiency can be increased. However, simultaneous elastic deformation in the horizontal plane 44 is unfavorable. Deformation of the fin in the horizontal plane 44 has a negative effect, as it causes lateral deflections of the fin during leg strokes. This can misalign the swimmer's ankle, resulting in increased muscle strain.

For this reason, it is crucial to adjust the elasticity of the elongated support 5 both in the vertical plane 43 and in the horizontal plane 44. The elasticity of the elongated support 5 in the vertical plane 43 is greater than in the horizontal plane 44. The elasticity in both planes can be regulated by the following structural elements: ribs 49, openings 50, as well as the interior spaces 51 present in the support 5. These interior spaces of the support 5 can be either closed or communicate with the external environment, allowing water to enter.

The combination of ribs, openings and interior spaces allows the elastic deformation of the elongated support to be regulated both in the vertical plane 43 and in the horizontal plane 44 (see Figure 13 and Figure 17).

The described fin allows the rotation angles p and<y> of each pair of blades 7 - 7i and 8 - 8i to be optimized. Lower rotation angles p and<y> provide a more powerful impulse for the swimmer, while higher values of these angles contribute to less muscular effort on the part of the swimmer.

A change in the position of the longitudinal axis 9 of the elongated support 5 relative to the longitudinal axis 10 of the foot part 1 allows the swimmer's muscular strength to be used highly effectively when performing the kicking motion with the fin.

Another factor contributing to the increased efficiency of the fin described is the elastic deformation of the blades 7 and 8 under the influence of water pressure. A bending of the blade, which increases from the axis of rotation 19 toward the trailing edge 18, reduces the hydrodynamic resistance of the blade.

The efficiency of the blades can also be significantly improved by including continuous water flow openings 24 in the aerodynamic blades 7 - 7i and 8 - 8i (see Figure 6).

The generated thrust can be adjusted by changing the surface size of the aerodynamic blades 7 and 8.

During the fin striking movements, the blades 7, 7i, 8, 8i perform limited rotational movements around their pivot or rotation axes 19, which are perpendicular to the longitudinal axis 9 of the support 5. The cross member 46, which connects the two blades of the same blade 7, 7i, 8, 8i, performs alternating tilting movements between the stops 47 and 48.

The term "blade" refers to the aerodynamic surface 21 of the blades.

During fin strokes, the cross member 46, which connects the blades 7 and 8, tilts freely within the opening 45, 45i between the stops 47 and 48, which limit the movement of the blades. This free tilting movement of the blades from one extreme position to the other requires significantly less time than a complete rotation. Consequently, the downtime is reduced.

Bench testing has shown that the problem of fin downtime can be almost completely solved by reducing the blade size while increasing their number and incorporating a free-articulation system.

The use of a single elongated support (5) connected to the foot part (1) can significantly contribute to reducing hydrodynamic resistance during kicking movements with the fin.

Since the swimmer alternates leg movements while moving forward in the water, the weight of the fin influences the inertial force that must be overcome to move forward. The use of a single elongated support (5) reduces the weight of the fin, which improves the efficiency of the swimmer's muscular strength.

In addition, the use of a single elongated support (5) simplifies the process of separating the support from the forefoot (1) (Figure 9). This disassembly capability reduces the overall dimensions of the fin, making it easier to transport to the place of use.

Compared to other design variants, the implementation of a single elongated support (5) also simplifies the mounting of the aerodynamic blades (7-7i and 8-8i) on the support, as well as their disassembly. This further facilitates the transport of the fin to the place where it will be used.

The ease of installation and disassembly of the aerodynamic blades (7-7i and 8-8i) also allows the use of multiple sets of blades with different characteristics according to the user's needs.

The elongated support (5) attached to the swimmer's foot, which forms the base of the swimming fin, remains unchanged.

The aerodynamic blade sets (7-7i and 8-8i) can be optimized to suit different purposes: one set for strong thrust swimming and another for leisurely swimming with minimal energy expenditure.

The proposed swimming fin can also have a modular construction. This means that, in its basic configuration, it includes, for example, three pairs of aerodynamic blades (7, 7a, 7b, 8, 8a, and 8b), which operate according to the principles described above. With three pairs of blades, smooth swimming with low energy consumption is expected. To increase the propulsion force, an additional module (11) of aerodynamic blades (7i and 8i) can be mounted (Figure 8).

The return spring (30) or spring mechanism can also be easily replaced with a device with different characteristics. This offers another possibility of configuring the swimming fin for use requiring powerful thrust or for relaxed swimming.

Alternatively, the blades (7-7i and 8-8i) can be mounted on the elongated support (5) by means of a so-called free joint (Figure 14 and 15). In this case, the blades (7-7i and 8-8i) are connected to each other by means of a flat cross member (46) passing through an opening (45, 45i) in the elongated support (5).

The opening (45, 45i) in the elongated support (5) has larger dimensions than the cross member (46) that passes through it. This opening has an irregular shape. Inside the opening (45, 45i) there are stops (47 and 48) that limit the rotational movements of the cross member (46) around the rotation axes (19) of the respective blades (7-7i and 8-8i). The surface of the opening (45, 45i) can be covered with a material that cushions the impact of the cross member (46) against the stops (47, 48).

This arrangement reduces the repetitive impact between the stops and the crossbar during each fin stroke, prolonging the life of the system and improving the swimmer's experience.

This design ensures that the recurring contact at each stroke of the fin between the stops (47, 48) and the cross member (46), which connects the blades (7 - 7i and 8 - 8i), is smoother. Figure 15 illustrates possible shapes of the openings (45, 45i) in the elongated support (5). These openings may take other shapes depending on the design or manufacturing requirements.

Due to the complexity of the manufacturing methods and construction solutions, the stops (47, 48), which limit the rotational movement of the cross members (46), can also be located outside the free joint, directly on the elongated support (5).

The cross member (46) is ideally located at the front of the blades (7 - 7i and 8 - 8i), as shown in Figure 16. Although it generally has a flat shape, it can be designed with other configurations according to the required specifications.

The free hinge may be laterally equipped with covers (52), as detailed in Figure 14. These covers may be formed by discs, include discs or be surrounded by them. The covers, preferably in the form of discs, define planes in which the rotation axes (19) of the blades (7, 7i, 8, 8i) lie perpendicularly. The covers (52) play a crucial role in preventing the openings (45, 45i) in the elongated support (5) from being blocked by elements such as algae or other debris. These covers may be integrated into the body of the support (5) or protrude outwards.

Highlighted elements of the swim fin design (depicted in Figures 1 to 17c):

- A fixing foot (1, 3, 4) that attaches to the swimmer's foot.

- A fin panel (2), which may be placed or fixed to the fixing foot.

This design provides an efficient technical solution to improve the functionality and durability of swimming fins.

The swimming fin panel (2), briefly referred to as the fin, includes an elongated support (5) to which the aerodynamic blades (7, 7i, 8, 8i, 21) are rotatably attached.

At least two aerodynamic blades (7, 7i, 8, 8i) are rotatably arranged on the sides of the support (5). These blades can rotate about pivot or rotation axes (19), which perpendicularly cross the longitudinal axis (9) of the elongated support (5). The blades are configured to oscillate in opposite directions, allowing back-and-forth movements in both directions within a predetermined angle.

The swimming fin is characterized by arranging the elongated support (5) in a movable manner relative to the swimmer's fixing foot (1, 3, 4), especially during the fin's stroke movements.

Swimming fins are characterized in accordance with an alternative or other object of the invention. The fin includes aerodynamic blades (7, 7i, 8, 8i) protruding from opposite sides of the elongated support (5). These blades, or their aerodynamic surfaces (21), are interconnected by a flat cross member (46) passing through a hole (45, 45i) in the elongated support (5).

The hole (45, 45i) in the support is designed to be larger than the cross member (46) that passes through it. Furthermore, said hole is equipped with stops (47, 48) in the form of projections to limit the movements of the cross member around the pivot axes (19) of the corresponding blades.

The aerodynamic blades (7, 7i, 8, 8i, 21) can incorporate discs (52) at their ends adjacent to the support (5), which function as covers to close the holes (45, 45i) present in the elongated support (5).

Each blade 7, 7i, 8, 8i includes at least one airfoil surface 21 forming a blade foil. Preferably, the blades 7, 7i, 8, 8i are composed of two blade foils designated as airfoil surfaces 21, with one blade foil on each side of the support 5. The airfoil surfaces 21 of the blades 7, 7i, 8, 8i are advantageously arranged facing each other on both sides of the longitudinal axis 9 of the elongated support 5, in a direction perpendicular to the pivot or rotation axes 19 crossing the longitudinal axis 9.

These may have individual pivot axes or pairwise shared pivot axes. With an individual pivot axis, each blade 7, 7i, 8, 8i includes a single blade blade extending on one side of the support 5. With pairwise shared pivot axes, a blade 7, 7i, 8, 8i comprises two facing blade blades extending on both sides of the support 5. The blades 7, 7i, 8, 8i can perform limited, reciprocating rotational movements about the predefined pivot axes 19.

In this way, the blades 7, 7i, 8, 8i, or their blade sheets with aerodynamic surfaces 21, can extend on both sides of the elongated support 5.

It is advantageous that the facing blade blades, mounted on a shared pivot axis 19, are connected in a fixed and non-rotatable manner to form a single blade 7, 7i, 8, 8i. The blades 7, 7i, 8, 8i, extending on both sides of the longitudinal axis 9 of the support 5, can be rotatably mounted around a common axis 19 arranged in the elongated support 5.

Opposing blade blades may be arranged so that they can rotate back and forth around a common pivot or rotation axis 19, shared by the pairs. However, these blades can perform rotational movements independently of each other, since they are not rigidly connected by a common connecting element.

It is advantageous if the elongated support 5 is arranged so that it can be moved relative to the swimmer's foot, especially during the kicking motion. This support can be connected to the foot via a hinged joint.

A hinge mechanism 27 may be arranged between the elongated support 5 and the foot attachment part 1, 3, 4. This mechanism allows a movable, preferably hinged, connection between the elongated support 5 and the foot attachment part. In this way, the elongated support 5 is hinged to the swimmer's foot, at least during the finning movements.

It is advantageous that the articulated design between the elongated support 5 and the foot fixing piece 1, 3, 4 is equipped with a spring load that acts against movement deviations.

The hinge mechanism 27 may include at least one return spring. In this case, the support 5 may be designed to be elastically deformable. Alternatively, the support 5 may be rigid and designed with sufficient stiffness to prevent deformations caused by forces applied by the user.

The elongated support 5 can rotate and/or flex relative to the foot attachment part 1, 3, 4 during flapping movements. The elasticity of the elongated support 5 is greater in a vertical plane 43 than in a horizontal plane 44, which is arranged perpendicular to the vertical plane 43. This horizontal plane 44 is defined by the aerodynamic blades and contains the longitudinal axis 9 of the support 5.

The elongated support 5 may include ribs 49, openings 50 (also called holes), and/or internal cavities 51, which may be filled with water or empty. These features allow the elasticity of the support 5 to be adjusted both in the vertical plane 43 and in the horizontal plane 44.

The elongated support 5 of the flap 2 may be partially composed of modules 11 including aerodynamic blades 7, 7i, 8, 8i.

The foot attachment part 1, 3, 4, which is attached to the swimmer's foot, may include a reinforced sole, referred to briefly as sole reinforcement 26. The elongated support 5 of the fin 2 is preferably connected to this sole reinforcement 26. It is particularly advantageous if the elongated support 5 is hinged to the sole reinforcement 26 of the foot attachment part 1, 3, 4.

For this articulated arrangement, a hinge mechanism 27 is preferably placed between the sole reinforcement 26 of the foot fixing piece 1, 3, 4 and the elongated support 5.

The elongated support 5 may be provided, at least on one side, with at least one projection 25, 25i limiting the rotation of the aerodynamic blades 7, 7i, 8, 8i around their pivot or rotation axes 19.

The longitudinal axis 9 of the elongated support is preferably oriented forwards in relation to the longitudinal axis 10 of the foot fixing piece 1. This longitudinal axis 9 of the elongated support 5 is ideally positioned with a downward inclination at an angle of 0° to 20° with respect to the longitudinal axis 10 of the foot fixing piece 1.

If a joint 27 is provided between the foot attachment part 1 and the support 5, the angle of inclination corresponds to a neutral average position of the support 5 relative to the foot attachment part 1. From this neutral average position, the support 5, arranged on the joint 27, can deflect upwards and downwards at approximately equal angles. In this neutral position, the mobility of the joint 27 is approximately equal in both directions.

The invention can be embodied by a swimming fin comprising:

A foot attachment device: Designated as foot attachment piece 1, 3, 4, which is placed on the swimmer's foot. A swim fin blade 2: Connected to the foot attachment device, which includes an elongated support 5 and at least two aerodynamic blades 7, 7i, 8, 8i. These blades are pivotally mounted on the elongated support 5 and preferably each include an aerodynamic blade surface 21 on both sides of the support. The aerodynamic blades are configured to move in a limited manner in both directions relative to the elongated support 5.

The swimming fin is characterized in that the elongated support 5 rotates and/or flexes, at least during the finning movements, relative to the device for attaching to the swimmer's foot and in addition the elasticity of the elongated support 5 is greater in the vertical plane 43 than in the horizontal plane 44. The device for attaching to the foot may include a sole with a sole reinforcement 26, to which the elongated support 5 is attached.

The elongated support 5 is preferably elastically deformable and is rigidly fixed to the sole reinforcement of the foot fixing device.

Alternatively, the elongated support 5 may be connected via a hinge 27 to the sole reinforcement of the swimmer's foot attachment device. This hinge 27 is preferably equipped with at least one return spring, while the elongated support 5 is elastically deformable.

It is also possible that the joint 27, known as the hinge, is equipped with at least one return spring, while the elongated support 5 is designed to be rigid.

The elongated support 5 may be provided with ribs 49, holes 50, and/or internal cavities 51, which may be filled with water or remain empty. These structural features are intended to adjust the elasticity of the support 5 both in the vertical plane 43 and in the horizontal plane 44.

Furthermore, the swimming fin blade 2 may be composed, at least partially, of modules 11 containing aerodynamic blades 7, 7i, 8, 8i.

It should be noted that the configurations described above represent only the proposed design, but do not limit it, and that those skilled in the art may develop a variety of alternative implementations without departing from the scope of the appended claims of the invention. The fact that certain criteria are listed in different subclaims does not imply that the combination of these criteria cannot be used to achieve a positive effect. The invention is particularly applicable in the field of development and manufacturing of diving or swimming fins.

Claims (13)

1. Swimming fin, comprising: - a foot part (1, 3, 4) that can be fixed to a swimmer's foot, and - a fin blade (2) attachable to the foot portion (1, 3, 4), comprising an elongated support (5) and at least two aerodynamic blades (7, 7i, 8, 8i) extending laterally from the support (5) and rotatable in both directions by a predetermined angle, characterized by a movable arrangement of the elongated support (5) relative to the foot portion (1, 3, 4) which can be fixed to the swimmer's foot, characterized by, The elasticity of the elongated support (5) is greater in a vertical plane (43) than in a horizontal plane (44) arranged perpendicular to this vertical plane (43), being normal to the vertical plane (43) encompassed by the aerodynamic blades and enclosing the longitudinal axis (9) of the support (5). 2. Swimming fin according to claim 1, in which a joint (27) is arranged between the elongated support (5) and the foot part (1, 3, 4). 3. Swimming fin according to claim 2, in which the joint (27) is provided with at least one return spring and the support (5) is designed to be elastically deformable. 4. Swimming fin according to claim 2, in which the joint (27) is provided with at least one return spring and the support (5) is designed to be rigid. 5. Swimming fin according to any of the preceding claims, in which the elongated support (5) rotates and/or bends relative to the foot portion (1, 3, 4) which can be fixed to the swimmer's foot during the kicking movements of the fin. 6. Swimming fin according to any of the preceding claims, in which the elongated support (5) has ribs (49), holes (50), internal cavities filled with water or without water (51) that serve to adjust the elasticity of the support (5) in the vertical (43) and horizontal (44) plane. 7. Swimming fin according to any of the preceding claims, in which the elongated support (5) of the fin blade (2) is composed at least partially of modules (11) with aerodynamic blades (7, 7i, 8, 8i). 8. Swimming fin according to any of the preceding claims, wherein the foot portion (1, 3, 4) that can be fixed to the swimmer's foot comprises a reinforced sole, to which the elongated support (5) of the fin blade (2) is fixed. 9. Swimming fin according to any of the preceding claims, in which the elongated support (5) is provided on at least one side with at least one projection (25, 25i) that limits the rotation of the aerodynamic blades (7, 7i, 8, 8i). 10. Swimming fin according to any of the preceding claims, in which the aerodynamic blades (7, 7i, 8, 8i) extend on both sides of the elongated support (5). 11. Swimming fin according to claim 10, in which the aerodynamic blades (7, 7i, 8, 8i) extending on opposite sides with respect to the longitudinal axis (9) of the support (5) are rotatably mounted around a common axis (19) on the elongated support (5). 12. Swimming fin according to any of the preceding claims, wherein the aerodynamic blades (7, 7i, 8, 8i) extending on opposite sides with respect to the longitudinal axis (9) of the support (5) are connected by a plate-shaped cross-piece (46) passing through a hole (45, 45i) in the elongated support (5), while the hole (45, 45i) in the elongated support (5) is equipped with blade movement limiters (47, 48) in the form of projections and has a larger size than the cross-piece (46) passing through it. 13. Swimming fin according to claim 12, in which the aerodynamic blades (7, 7i, 8, 8i) are provided at their ends facing the support (5) with discs (52) that close the holes (45, 45i) in the elongated support (5).