JPH01129862A - Foot fin - Google Patents

Abstract

PURPOSE: To effectively convert kinetic energy of a lower limb to a thrust by arranging a foot inserting part and a web part, and the cross section of the web part in the direction of water flows is made to have the shape of a wing. CONSTITUTION: One end of a rod 4 made of an elastic material is fastened on a bottom plate part 2b made of a rigid material. On the other hand, a web part 1 is fastened on the other end thereof 4. The web part 1 has a cross section of the shape of a symmetrical wing in the direction of advancing, is constituted of a rubber or a rubber-like elastic material and moreover, a synthetic resin material and the synthetic resin material as core material is covered with the rubber or the rubber-like elastic material. The web part, which has a wing- shaped cross section in the direction of the flow of water, not only makes the flow of water hard to peel as compared with the type with a rectangular shape but also a force L larger compared with the type of the same dimension. This enables effective conversion of kinetic energy applied by a lower limb to a thrust.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to flippers used for diving, swimming, etc., and in particular to flippers that can efficiently convert the movement of the lower limbs into propulsive force. be.

(Prior Art) Conventionally widely used foot soles, for example, as shown in FIG. 2, and rubber heel straps 3 whose end portions are connected to both sides of the foot insert 2, respectively. Note that the webbed portion 1 has a rectangular or wedge-shaped cross-sectional shape in the flow direction A, and extends parallel to the flow direction in order to improve bending rigidity in a plane that is orthogonal to the flow direction and includes the webbed portion. A plurality of ribs 1a are provided on the surface thereof.

When using this type of foot, the heel strap 3 is hooked and passed around the heel after inserting the foot pad into the foot opening, and the lower leg is moved back and forth alternately in this state.
The reciprocating motion is converted into propulsive force. Specifically, if the forward speed of the swimmer is U and the relative speed of the lower limbs with respect to the water is
It will receive a force similar to the lifting force acting on a flat plate placed against a water stream forming an angle of (V/U), and will generate a propulsive force proportional to the component of that force in the forward direction.

(Problems to be Solved by the Invention) However, with such conventional foot fins, as schematically shown in FIG. Therefore, the flow that has passed through the tumescent area will cause separation in the webbed area, creating a vortex. This vortex flows downstream and forms an even larger vortex region.

For this reason, the pressure on the free end side of the webbed part 1 is significantly lower than the pressure on the tumor side, and there is a problem in that a force in the opposite direction to the propulsion direction acts as resistance, reducing the thrust force. Ta. Moreover, since the ribs 1a are provided on both sides of the webbed part, the water flow cannot flow smoothly along the sides of the webbed part during the reciprocating movement of the ribs 1a, and as with the seed part, the water flow separates. As a result, more resistance acts on the webbed portion. Therefore, the conventional foot soles have a problem in that they have a large resistance and cannot efficiently convert the kinetic energy of the lower limbs into propulsive force.

The present invention was made in view of such problems, and an object of the present invention is to provide flippers that can efficiently convert kinetic energy of the lower limbs into propulsive force.

(Another Means to Solve the Problem) In order to achieve this object, the flippers of the present invention include at least a foot insertion portion and a webbed portion, and the cross-sectional shape of the webbed portion in the water flow direction is airfoil-shaped. Become.

(Function) In this flipper, the cross-sectional shape of the webbed part in the flow direction is airfoil-shaped, so the water flowing along the webbed part flows along its surface, and there is almost no separation, and vortices are generated. The kinetic energy of the lower limbs can be efficiently converted into thrust without having to do so.

(Example) Examples of the flippers of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention, in which the upper portion 2a of the foot insert 2 is made of rubber or rubber-like elastic material in consideration of the fit to the foot, similar to the conventional one. On the other hand, the bottom plate part 2b of the foot insertion part is
It is made of rigid materials such as synthetic resin and metal.

However, the present invention is not limited to this embodiment, and it goes without saying that the bottom plate portion may be made of rubber or a rubber-like elastic material. Similarly, the heel strap 3 made of rubber or a rubber-like elastic material has both ends connected to the side walls 2c of the upper part 2a of the foot insertion part, and elastically straps the heel of the swimmer inserted into the foot insertion part 2. It is conventional to hold the swimmer's feet in place and prevent the swimmer's feet from coming off the flippers.

One end of a rod 4 made of rubber or a rubber-like elastic material or a flexible synthetic resin material is fixed to the bottom plate portion 2b made of a rigid material. On the other hand, a webbed portion l is fixed to the other end of the rod 4. This webbed part 1 is made of rubber or a rubber-like elastic material, which has a symmetrical airfoil cross-sectional shape in the forward direction shown by arrow A in the figure, or a synthetic resin material or a synthetic resin material as a core material. It is made of a material covered with an elastic material. In this embodiment, the webbed part 1, the footrest part 2, and the rod 4 are constructed separately, but they may be constructed as one body, and the present invention is not limited to this embodiment.

Next, the operation of the flipper of the present invention will be explained with reference to FIG. 1(b). When the forward speed of the swimmer is U and the relative speed of the lower limbs to the water is They are equivalent, and a force similar to a lifting force acts on the webbed portion in a direction perpendicular to the water flow.

Therefore, the web portion generates a force component of the force represented by L sin α in the traveling direction A as a propulsive force.

Moreover, the web section has an airfoil-shaped cross section in the water flow direction, so compared to conventional ones with a rectangular cross section, the water flow is less likely to separate; Since the force is greater than that of the lower limbs, the kinetic energy given by the lower limbs can be effectively converted into propulsive force. Note that the force represented by L cos α also acts on the webbed part, but the direction of movement of the webbed part is reversed when the swimmer makes one reciprocation of the lower limb, and the integrated value of the component force represented by L cos α is zero when viewed as a whole. becomes.

FIGS. 2(a) and 2(b) are perspective views showing another embodiment of the present invention, in which the webbed part 1 and the foot insert part 2 are connected using a pair of rods 4a, respectively. In this way, by connecting a pair of rods, compared to the case where a single rod is used, the resistance due to water when moving the flippers is reduced, and the weight of the rod part and, by extension, the entire flipper is reduced. Weight can be reduced. Moreover, since the webbed part 1 is located apart from the foot insertion part 2,
There is almost no turbulence in the water flow due to the presence of the foot insertion part 2. In particular, as shown in FIG. 2(b), by using a pair of rods 4b having a cross-shaped cross section, the rigidity of the rod portion can be increased.

In addition, in the flipper of this example, the planar shape of the webbed part l is rectangular, but the cross-sectional shape in the forward direction A is a symmetrical airfoil shape, and its function is as shown in Fig. 1 (a). There is no difference from that of a flipper, and the operation as a flipper is therefore the same as that of the embodiment shown in FIG. 1(a), so a description thereof will be omitted.

FIG. 3 shows yet another embodiment of the invention.

In this embodiment, the web part 1 and the foot insertion part 2 are integrally constructed without using a rod. In this embodiment as well, the cross-sectional shape of the webbed part 1 in the forward direction A is similar to that of the above-mentioned embodiment, and a part of the webbed part 1 is extended to the side of the foot insertion part 2. The water flow can flow along the airfoil-shaped webbed part, and there is almost no loss due to turbulence in the water flow. With such a configuration, it is also possible to integrally mold the flippers, and if necessary, an appropriate reinforcing plate, such as a thin metal plate, can be inserted across the bottom plate 2b and the webbed part l to make the webbed. It is also possible to provide the desired stiffness in the direction of movement of the part.

FIG. 4 shows another embodiment of the flipper of the present invention. This embodiment differs from the previously described embodiments, except that the cross-sectional shape of the webbed portion 1 in the water flow direction is shaped like an asymmetrical airfoil.
It has a similar configuration to the flipper shown in the figure.

This takes into account the physical characteristic that the leg force is greater when kicking off than when kicking off the leg, and by making the cross-sectional shape of the webbed part 1 into an asymmetrical airfoil shape, the foot Greater propulsive force can be obtained during the downstroke of the fins, that is, when kicking off the legs. In addition,
During the upstroke of the flippers, the leg force itself is small, so the disadvantages of having an asymmetrical wing-shaped web part do not pose a problem. On the other hand, as shown in Figure 4(b), when on the ground or on a ship, the tip of the webbed part L will bend back, so the tip will not get caught on the ground or deck when walking. This makes it extremely easy to walk even when wearing flippers.

(Effects of the Invention) As detailed above, according to the present invention, the cross-sectional shape of the webbed portion of the flipper in the water flow direction is airfoil-shaped, and water flows along the surface of the airfoil. The water flow does not separate along the webbed part and create resistance, and the force generated on its surface that acts as propulsive force increases, making the motion transmitted by the lower limbs more efficient (obtaining flippers that convert into propulsive force) Can be done.

[Brief explanation of the drawing]

FIG. 1(a) is a perspective view showing an embodiment of the present invention, FIG. 1(b) is an explanatory view showing the operation of the flipper shown in FIG. 1(a), FIGS. 4 are perspective views showing other embodiments of the present invention, and FIGS. 5(a) and 5(b) are explanatory diagrams showing conventional flippers and their operation. 1... Webbed part 1a... Rim 2...
Foot insert part 2a... Upper part 2b...
Bottom plate part 2c...Side wall part 3...Heel strap 4...Rod Fig. 1, a; , :b' Usage No. 3 = Fig. 4'a; b. Figure 5

Claims (1)

[Claims] 1. A flipper comprising at least a foot insertion part and a webbed part, the webbed part having an airfoil cross-sectional shape in the water flow direction.