Swing practice tool

Abstract

According to the present invention, by swinging a bat that allows visual recognition of the centrifugal force of the bat, a swing utilizing the centrifugal force of the bat can be acquired. This swing practice tool comprises: a body part 1; a head part 4 at a front end connected to the body part 1; and a grip part 2 at a rear end. The body part 1 includes: a cavity 5 having a liquid 8 movable therein; and a visual recognition part 10 that allows the liquid 8 moving in the cavity 5 during swinging to be visually observed from the outside.

Description

Swing training tool

[0001] The present disclosure relates to a swing training tool used for swing training such as baseball, softball, golf, cricket, tennis, etc.

[0002] Conventionally, a swing training tool has, for example, a weight that slides in the tip direction of a baseball bat attached to the bat. When the bat is swung, the weight slides by centrifugal force and collides with the head part side, and there is a bat for dry swing that can grasp the meet point through a collision sound and feeling similar to hitting a ball (see Patent Documents 1 and 2). However, these bats have a problem that the centrifugal force of the swing cannot be recognized visually.

[0003] Japanese Patent Application Laid-Open No. H8-24386, Japanese Patent Application Laid-Open No. H8-33744

[0004] The present disclosure has been further developed for the purpose of solving the above drawbacks. One of the purposes of the present disclosure is to provide a swing training tool that can visually recognize the centrifugal force of the swing. Note that the description of the purpose and problems of the present disclosure does not prevent the existence of other purposes and problems. Also, the aspects of the present disclosure do not need to solve all of these problems. Furthermore, other problems can be extracted from the description of the specification, drawings, and claims of the present disclosure. Means for Solving the Problems and Effects of the Invention

[0005] A swing training tool according to an aspect of the present disclosure includes a main body part, a head part on the tip side connected to the main body part, and a grip part for gripping on the rear end side. The main body part has a cavity part having a liquid that can move inside, and a visual recognition part that can visually recognize the liquid moving inside the cavity part during a swing. The above configuration has the feature that the movement of the liquid due to the swing can be recognized sensuously and the centrifugal force of the swing can be recognized visually.

[0006] This is a schematic perspective view showing an example of the swing training tool (bat) as used in a ready position according to one embodiment of the present disclosure. This is a schematic perspective view showing another embodiment of the bat body and the viewing section. This is a schematic perspective view showing another embodiment of the bat body and the viewing section. This is a schematic perspective view showing another embodiment of the bat body and the viewing section. This is a schematic cross-sectional view showing another embodiment of the bat body, the viewing section, and the reinforcing section. This is a schematic cross-sectional view showing another embodiment of the reinforcing section. This is a schematic cross-sectional view showing another embodiment of the reinforcing section. This is a schematic perspective view showing an example of the inlet and outlet. This is a schematic plan view showing an example of the scale. This is a schematic sequence diagram showing an example of the swing of the swing training tool (bat). This is a schematic perspective view showing a swing training tool (bat) according to another embodiment. This is a schematic cross-sectional view showing the bat body and hollow section of Figure 11. This is a schematic cross-sectional view showing another embodiment of the bat body and hollow section. This is a schematic cross-sectional view showing another embodiment of the bat body and the reinforcing section. This is a schematic cross-sectional view showing another embodiment of the swing training tool. This is a schematic sequence diagram showing an example of the swing of the swing training tool (golf club).

[0007] The present disclosure will be described in detail below with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "up," "down," and other terms including these) will be used as needed. The use of these terms is for the purpose of facilitating the understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. Also, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components. Furthermore, the embodiments shown below are concrete examples of the technical concept of the present invention and do not limit the present invention to the following. In addition, the dimensions, materials, shapes, relative arrangements, etc. of the components described below are intended to be illustrative, and not to limit the scope of the present invention unless specifically stated otherwise. Furthermore, the content described in one embodiment or example is applicable to other embodiments and examples. Also, the size and positional relationships of the components shown in the drawings may be exaggerated to clarify the explanation. In this disclosure, the direction of the central axis of the main body 1 is defined as the X direction, and the direction perpendicular to the central axis is defined as the Y direction.

[0008] This disclosure may be defined by the following configuration and features. A swing training aid according to one embodiment of this disclosure comprises a main body, a front-end head connected to the main body, and a rear-end grip, the main body having a cavity containing a movable liquid and a visibility portion that allows the liquid moving inside the cavity during a swing to be seen from the outside.

[0009] The above configuration features a main body with a hollow section containing a movable liquid and a viewing section that allows the liquid moving within the hollow section to be seen from the outside during a swing. This allows for both intuitive recognition of the liquid's movement during a swing and visual recognition of the centrifugal force of the swing. The movement of the liquid within the hollow section can be grasped and recognized both physically and intuitively during a swing. In addition, the centrifugal force during a swing can be visualized by simultaneously observing the liquid's movement through the viewing section, allowing users to better recognize and experience whether or not they are utilizing centrifugal force during their swing. Users can see the liquid moving outward due to centrifugal force through the viewing section during a swing, and can also swing while visually observing the liquid moving within the hollow section visible from the outside. The smoothness of the swing, swing speed, degree of centrifugal force utilization, and whether or not the swing is utilizing centrifugal force can be confirmed by the user or a third party based on the liquid's movement, making it useful for video review as well. Through the movement of liquid and centrifugal force, the movement, rotation, coordination, and trajectory of the arms, upper body, hips, and lower body can be observed and confirmed. By using the above swing training equipment, you can master a swing that utilizes centrifugal force and shorten the time it takes to improve your swing. It is also useful for a smooth swing that efficiently transfers centrifugal force to the ball, mastering the amount of force to apply, including before and after impact, widening the sweet spot, and improving swing speed.

[0010] Traditional swing training aids (bats) rely on the sound of impact and the feel of the weight hitting the ground to determine the sweet spot. The impact sound is produced when the centrifugal force acting on the weight during the swing causes it to slide towards the tip and collide with the head. While the sound is instantaneous, it is not easy to recognize the exact moment of impact, and it is impossible to judge from the sound whether the centrifugal force is favorable or not. For most users, except for advanced players who have developed their own swing form and can freely produce the sound, practicing swings while listening to and consciously focusing on the impact sound and feel is not easy. It is difficult to concentrate on the swing and perform a swing with proper hip rotation while being conscious of the impact sound and feel. If you focus too much on making the sound, the point of impact, and the feel of the impact, you will neglect your swing and form, and correcting this will be even more difficult. In the first place, it is not easy to master a swing that utilizes centrifugal force based on the sound and impact feel produced all at once. Furthermore, traditional swing training aids produce a louder and higher-pitched sound the harder you swing, which tends to encourage forceful swings. This weakens awareness of centrifugal force and form, and can lead to tension and a breakdown of the swing. Conventional swing training aids require repeated practice swings until a certain swing shape is achieved. Only after the form is solidified can the user consciously recognize and understand the sound and impact sensation, and then attempt to master a swing that utilizes centrifugal force. This is a long and difficult process. In contrast, the swing training aid disclosed herein allows the user to intuitively experience the movement of liquid and visually recognize the centrifugal force of the swing through the visible movement of the liquid. Furthermore, unlike conventional aids that focus on a single point in time, the range over which the liquid movement can be recognized is wide. The movement and process of the liquid moving towards the head at the tip due to centrifugal force are continuously and continuously visualized during the swing, allowing the user to visually perceive the liquid movement while swinging. The configuration of this disclosure allows the user to feel and become aware of the centrifugal force of the swing more directly and in real time by experiencing and visualizing the liquid movement. This is only possible because of the unique configuration that has a visual part that allows the liquid moving inside the cavity during the swing to be seen from the outside, adding visuals to the sensory experience and simultaneously aligning the sensory experience with the visuals. Moreover, regardless of the user's skill level, even beginners can recognize the liquid movement caused by the centrifugal force of the swing from the visually observable part.The amount, position, and speed of liquid movement allow for easy visual recognition of centrifugal force. Furthermore, by repeatedly practicing swings while checking and adjusting the swing trajectory and body coordination, it becomes possible to master a swing that utilizes centrifugal force more efficiently in a shorter period of time. In addition, the visual recognition of liquid movement in the viewing area eliminates collision sounds, eliminating the need to swing forcefully due to impact noise, thus eliminating factors that can disrupt the swing.

[0011] Furthermore, conventional swing training aids have an axis that slides the weight along the head side (tip side) of the bat in the axial direction (X direction), which restricts the direction of movement of the weight to the axial direction and results in significant frictional resistance between the weight and the axis. In contrast, the configuration of this disclosure allows the liquid inside the cavity to move freely without restriction, does not require an axis for the direction of movement, and does not create frictional resistance like that between the weight and the axis. A fixed amount of liquid does not have a specific shape, and its position and shape are determined according to the internal shape of the cavity, gravity, and centrifugal force. It can deform without resistance, move freely, and faithfully and immediately represent and reflect the centrifugal force of the bat caused by the swing as liquid movement. The above swing training aid can visually visualize swing habits, swing trajectory fluctuations, swing acceleration, and the difference between initial and final velocity as liquid movement in the visible area, which are difficult to reflect or recognize with conventional swing training aids.

[0012] Other embodiments of the swing training device according to this disclosure, in addition to the above embodiments, allow 40% or more, or 80% or more, of the outer surface of the main body to be made visible, or allow the entire outer surface of the main body to be made visible. The above configuration has the advantage that a large area of ​​40% or more of the outer surface of the main body can be made visible, and that the movement of liquid can be recognized from the large visible area of ​​80% or more. Furthermore, because the entire outer surface of the main body is visible, it can be seen over a wide area regardless of posture or angle. It also has the advantage of having a cylindrical visible area with a hollow part inside, which allows light to pass through from all directions, making it even easier to see the movement of liquid from the visible area.

[0013] Other embodiments of the swing training aid according to this disclosure may have a viewing section on the rear of the main body in addition to the above embodiments. This configuration has the advantage that the movement of the liquid can be visually observed from the rear of the main body, especially at the point of contact with the ball during the swing. The rear of the main body refers to the rear of the main body with respect to the direction of movement during the swing.

[0014] Other embodiments of the swing training aids of this disclosure can, in addition to the above embodiments, use a liquid containing water or oil. Water has low viscosity, its direction of movement is not restricted, it can be deformed without resistance, it can move freely, and it has the advantage of faithfully and immediately representing, reflecting, and visualizing the centrifugal force of the swing as liquid movement. Oil has the advantage of allowing selection of its type and viscosity, and it can represent, reflect, and visualize the centrifugal force of the swing as liquid movement different from that of water. It is possible to use water and oil that do not dissolve and mix, and multiple types of oil can be used.

[0015] Other embodiments of the swing training aids of this disclosure may, in addition to the above embodiments, include a colored liquid. The above configuration has the advantage that the liquid can be transparent or opaque and colored to a color other than colorless, and that by mixing the colored liquid with an uncolored liquid, the movement of the liquid from the viewing area can be easily seen by the colored liquid.

[0016] In addition to the above embodiments, swing training aids according to other embodiments of this disclosure may have both liquid and gas present in the cavity. This configuration has the advantage that, by not completely filling the cavity with liquid and instead allowing gas to be present in the gaps, the liquid can move smoothly within the cavity, and the amount of liquid can be reduced, resulting in a lighter weight.

[0017] Other embodiments of the swing training aid of this disclosure, in addition to the above embodiments, have a main body that comprises an outer cylindrical shape and an inner cylindrical shape disposed within the outer cylindrical shape, and the inner cylindrical shape may have a cavity. This configuration is a simple structure in which the main body has two cylindrical shapes, and can improve strength, rigidity, and durability. Furthermore, by narrowing the inside of the inner cylindrical shape, the cavity can be made smaller, the amount of liquid can be reduced, the weight can be reduced, and the impact on the swing can be minimized. Moreover, the cavity can be positioned to include the central axis of the inner cylindrical shape, resulting in good swing balance, and the centrifugal force and liquid movement caused by the swing can be easily felt and seen. Furthermore, the ratio of the length in the X direction to the inner diameter of the cavity can be increased, making it easier to perceive the liquid movement and centrifugal force.

[0018] Other embodiments of the swing training aid according to this disclosure, in addition to the above embodiments, have a main body that includes an outer cylindrical shape and an inner cylindrical shape disposed inside the outer cylindrical shape, and a cavity between the inner surface of the outer cylindrical shape and the outer surface of the inner cylindrical shape. This configuration allows the cavity to be positioned close to the outer cylindrical shape which has a viewing area, making it easier to visually observe the movement of the liquid. Furthermore, by narrowing the gap between the inner surface of the outer cylindrical shape and the outer surface of the inner cylindrical shape, the cavity can be made smaller, the amount of liquid can be reduced, the weight can be reduced, and the impact on the swing can be minimized. Moreover, the ratio of the length in the X direction to the inner diameter of the cavity can be increased, making it easier to visually observe the movement of the liquid and to recognize centrifugal force more easily.

[0019] Other embodiments of the swing training aids of this disclosure may, in addition to the above embodiments, further have an injection port for injecting liquid into the cavity. The above configuration has the advantage of being able to adjust and change the amount and mass of liquid. If the weight exceeds the user's skill and physical strength, the load on the swing will be too great, the influence of the liquid on the swing will be too great, hindering a smooth swing and potentially disrupting their form. However, the above configuration can resolve these problems by optimally setting the amount and mass of liquid. Furthermore, the liquid can be replaced, allowing for hygienic use.

[0020] In addition to the above embodiments, the swing training aid according to other embodiments of this disclosure allows the amount of liquid to be between 10% and 70% of the volume of the cavity. The above configuration has the advantage that the liquid can move smoothly by centrifugal force and is easy to see, while keeping the liquid within the above range. On the other hand, if there is too little liquid, it is difficult to see the movement of the liquid, and on the other hand, if there is too much liquid, it cannot move smoothly and the liquid becomes too heavy. Therefore, keeping the liquid within the above range achieves smooth liquid movement, ease of visibility, and an optimal mass balance.

[0021] In addition to the above embodiments, the swing training aid according to other embodiments of this disclosure may have a main body that is a bat body, and the bat body may have a viewing section that allows the liquid moving inside the cavity during a baseball or softball swing to be seen from the outside. The above configuration has the advantage of making it easier to perceive centrifugal force in addition to the visual perception of liquid movement during a swing, such as in baseball.

[0022] In addition to the above embodiments, a swing training aid according to another embodiment of the present disclosure has a main body which is a shaft, and the hollow portion has a first hollow portion within the shaft and a second hollow portion within the head portion that communicates with the first hollow portion, and may have a viewing portion that allows the liquid moving within the hollow portion to be seen from the outside during a golf swing. The above configuration has the advantage of making it easier to perceive centrifugal force in addition to the visual perception of the liquid movement during a golf swing.

[0023] The swing training aid comprises a main body, a head connected to the main body at the front end, and a grip at the rear end for holding. The main body has a hollow section containing liquid and a visibility section that allows the liquid moving within the hollow section during the swing to be seen from the outside. The swing training aid comprises a main body, head, and grip section with shapes and configurations suitable for various sports such as baseball, softball, golf, cricket, and tennis. It is used as a training aid in which the user grasps the grip and rotates the main body (including the head) in a swing, as illustrated below. (Embodiment 1)

[0024] The swing training tool 100 according to Embodiment 1 illustrated in Figure 1 is a bat 101 with a shape similar to a baseball or softball bat, and allows for bat swing practice. The bat 101 comprises a bat body 1 having a hollow section 5 in which liquid 8 can exist, a head section 4 at the front end connected to the bat body 1, and a grip section 2 at the rear end. The bat body 1 has a hollow section 5 in which liquid 8 exists, and a viewing section 10 that allows the liquid 8 moving inside the hollow section 5 due to centrifugal force during a swing to be seen from the outside. The bat 101 can be used for practice swings and / or actual hitting. Actual hitting practice allows for checking the feel of hitting, the contact point, timing, etc., by, for example, tossing, tee batting, or even hitting balls thrown by a pitcher. (Bat body 1, grip section 2, head section 4)

[0025] The bat body 1 is connected to the head 4 and the grip 2, and has a hitting section 3 for hitting the ball, the hitting section 3 including a core 3a. The bat body 1 in Figures 1 and 5 has a cylindrical shape 1A with a hollow cavity 5 inside, and its outer shape is mainly composed of a curved cylinder or a frustum of a cylinder. The cylindrical shape 1A includes cylinders, rectangular tubes, frustums of a cylinder, etc. The cylindrical shapes 1A in Figures 1 and 5 have the same and different outer diameters, the hitting section 3 has a thicker portion than the grip 2, and has a frustum of a cylinder whose outer diameter tapers from the hitting section 3 towards the grip 2. For example, the outer diameter of the bat body 1 (hitting section 3) is, for example, 1.5 times or more, preferably 2 times or more, than that of the grip 2. For example, the outer diameter of the bat body 1 (hitting section 3) can be 4 cm or more and 10 cm or less, and preferably 5.5 cm or more and 7.5 cm or less. The outer diameter of the grip 2 can be 1 cm or more and 5 cm or less, and preferably 2 cm or more and 4 cm or less. The bat body 1 has a grip section 2 connected to its rear end, which the batter holds with both hands (or one hand). The grip section 2 has a grip end 2a at its lower end and can be overlapped with rubber, tape, resin, etc. The head section 4 can have a flat surface or an uneven surface, and can have a shape that is recessed inward from the tip of the bat body 1 or protrudes outward.

[0026] The mass of the bat body 1 (excluding the liquid 8) can be, for example, 100g or more and 1kg or less, preferably 200g or more and 800g or less. The length of the bat 101 can be, for example, 40cm or more and 1.3m or less, preferably 60cm or more and 1m or less, and more preferably 75cm or more and 90cm or less. The length of the bat body 1 can also be, for example, twice or more the length of the grip portion 2, preferably 2.5 times or more. This disclosure does not specify the shape, size, length, outer diameter, material, mass, etc., of the bat body 1, and the bat body 1 containing (or excluding) the liquid 8 can be within or outside the specified range for use in a game. For example, the bat body 1 can be made lighter and / or shorter or thinner than specified to reduce the load and resistance of the swing, allowing for an easy swing without worrying about the weight. On the other hand, the bat body 1 can be made heavier and / or longer than specified to increase the swing load and slow down the swing, making it easier to recognize and be aware of the liquid movement, body axis rotation, coordination of each part, and swing trajectory.

[0027] The bat 101 can be made of resin, such as FRP, polycarbonate, acrylic, polyvinyl chloride, fiberglass, glass fiber composite, carbon fiber composite, or fiber-reinforced plastic; metal, such as alloys containing aluminum, duralumin, iron, copper, titanium, or stainless steel; or wood, such as wood or bamboo. It can also be made by combining multiple materials containing any of these materials, or by including other materials such as foam, elastic members, or shock absorbers, and can be constructed by joining, connecting, laminating, or arranging. This disclosure does not specify a method or process for manufacturing the bat 101. The bat 101 can have two or more of the bat body 1, head 4, and grip 2 as an integrated structure, and each can be made of one or more members. For example, resin, metal, etc. can be placed in predetermined positions and insert molded. The bat body 1 and hitting section 3 have their mass and center of gravity determined by their material, thickness, and shape, and can be laminated and connected with plates, sheets, films, reinforcements, elastic members, etc. It can also be easily manufactured at low cost by processing commercially available or existing products, or a bat body 1 made of metal such as aluminum. For example, the cylindrical 1A can be manufactured by partially opening or notching the sides and tip, and then closing or covering the openings and notches with a translucent viewing section 10, while maintaining the original strength of the bat body 1 in the parts other than the openings. Furthermore, by adjusting the size, shape, number, and arrangement of the openings, it is possible to achieve both ease of recognizing liquid movement from the viewing section and strength, and both can be adjusted.

[0028] The bat 101 can be used by both left-handed and right-handed batters, but Figure 1 shows an example of a right-handed batter holding the bat 101. The batter's swing in Figure 10 goes from the top position through approach, impact, and follow-through. In the bat 101, the liquid 8, which was located at the bottom grip section 2 inside the hollow section 5 at the top position, moves towards the head section 4 at the tip due to the centrifugal force of the swing, and passes through impact with the liquid 8 inside the tip hollow section 6. The viewing section 10 allows the user to visualize the movement and position of the liquid 8 during the swing, and the bat 101 allows the user to feel the liquid movement during the swing more clearly. The bat 101 is useful for swing practice that focuses on centrifugal force, and allows the user to efficiently learn a swing that efficiently transfers centrifugal force to the ball. It is also useful for correcting and modifying form and swing trajectory. For example, the visualization of liquid movement in the viewing section 10 of the bat 101 allows for effective and efficient practice of inside-out swings and swings that are approximately parallel to the direction of ball movement. When the bat swings outside-in (a so-called door swing), the centrifugal force transfer occurs before the point of impact (towards the catcher), making it difficult to transfer the bat's centrifugal force to the ball at the desired point of impact. By swinging the bat inside-out, the centrifugal force transfer is more likely to occur at the point of impact, making it easier to transfer the bat's centrifugal force to the ball, and bat 101 is suitable for practicing this technique. Also, in the case of a downswing, the direction of the ball's movement and the swing trajectory intersect at a single point, and it is necessary to transfer the bat's centrifugal force at this narrow intersection, making it difficult to increase the ball contact rate and transfer centrifugal force to the ball. By widening the area at impact where the bat is in a level swing or parallel (or nearly parallel) to the direction of the ball's movement, the direction of the ball's movement and the swing trajectory become a line or plane, widening the area where the ball is hit, making it easier to increase the contact rate, making it easier to transfer the centrifugal force of the bat to the ball at the point of impact, and making it easier to respond to changes in ball speed and curveballs. Bat 101 is suitable for this practice due to its characteristics in terms of the fluid movement of centrifugal force, trajectory, and finish position.Furthermore, the bat 101 is useful because, starting from a moderately relaxed posture with the bat held upright at the top position, the swing is performed in conjunction with the rotation of the hips while feeling (and utilizing) the weight of the bat. This approach is highly compatible with an inside-out swing, and because the movement of the liquid in the visual section 10 occurs in a wide contact area including the impact position, the centrifugal force of the bat can be efficiently transferred to the ball. This is because, at the top position, the liquid 8 located at the bottom of the cavity 5 moves from the approach to the contact area in the head section 4, and this can be seen and confirmed in the visual section 10 while swinging. In addition, the more the swing rotates around the body axis, the faster the swing speed, and the smoother the swing with less loss in body movement, coordination, and bat trajectory, the greater the centrifugal force can be generated, making the bat 101 useful. (Cavity 5).

[0029] The bat 101 has a cavity 5 containing a liquid that can move within it, either entirely or partially, and a viewing section 10 is provided on the wall surface 1a covering the cavity 5 so that the movement of the liquid inside can be visualized from the outside. The bat 101 (bat body 1) has an elongated shape extending in the X direction, and the length of the cavity 5 and viewing section 10 can be secured by making the whole or partially cylindrical 1A. The movement of the liquid inside the cavity 5 during a swing can faithfully and immediately reflect the centrifugal force of the swing, as well as the posture, movement, and trajectory of the bat, and the visible liquid movement is useful for checking and correcting the swing trajectory and form. For example, different liquid movements occur when the bat is swung vertically, horizontally in a level swing, diagonally in an upper swing, down swing, or undulating swing, and different liquid movements occur depending on whether the grip end 2a is used as a pivot point or when the grip end 2a is moved, as well as the way the movement occurs. The bat 101 allows the liquid 8 inside the hollow section 5 to move towards the tip, shifting the bat's center of gravity. This makes it easier to feel and be aware of centrifugal force, which is useful for practicing to increase hitting distance. The tip and rear ends of the hollow section 5 can be closed and sealed with the head section 4, the grip section 2 (grip end 2a), or a sealing lid.

[0030] Figures 1 and 5 show that the entire or most of the bat body 1 is a hollow cylindrical shape 1A with a cavity 5 inside. The cavity 5 is a hollow region having a length in the X direction and an inner diameter (width) in the Y direction. By making the cavity 5 long, the distance the liquid 8 moves due to centrifugal force during the swing can be increased, making the movement of the liquid easier to feel, and the liquid movement visible from the viewing area 10 can be extended. The larger the inner diameter, the greater the amount of liquid that can be moved at once. The cavity 5 can be positioned between the head part 4 and the grip part 2 to ensure a sufficient distance for the movement of the liquid 8, but the cavity 5 can be further extended to the grip part 2. At the top position, the cavity 5 inside the grip part 2 can start the liquid movement from a lower position. The bat body 1 has all or part of the hollow portion inside the cylindrical shape 1A as the cavity 5. The length of the cavity 5 in the X direction can be longer than the length (h) of the viewing area 10 in the X direction, or it can be less than or equal to the length (h). The viewing unit 10 can visualize a portion of the liquid movement within the cavity 5 within its range, for example, it can visualize the leading edge where the liquid ultimately moves, as well as the intermediate parts leading up to it, and can further expand the range of visible liquid to include the moved liquid 8 and the liquid 8 before it moved.

[0031] The cavity 5 can have a cross-sectional shape in the Y direction that is, for example, a circle, a polygon, or other shapes, and can be regular or irregular, symmetrical or asymmetrical. Furthermore, the cross-section can have the same or different shapes, widths, inner diameters, and diagonal lengths. The cavity 5 within the cylindrical bat body 1 can be shaped to conform to the outer shape of the bat body 1, and can be approximately cylindrical, matching the outer shape (approximately cylindrical) of the bat body 1, with the inner diameter decreasing towards the grip portion 2. The inner surface of the bat body 1 covering the cavity 5 is a smooth surface (curved surface, flat surface) that allows the liquid 8 to move smoothly, and can faithfully reflect the centrifugal force from the swing in the movement of the liquid towards the tip.

[0032] The cavity 5 can be provided with guide sections and flow paths on the wall surface 1a covering the cavity 5 to guide the liquid 8 moving in the X direction towards the tip by centrifugal force in a predetermined direction. The guide sections and flow paths can guide, direct, and regulate the movement of the liquid, and adjust the amount, direction, timing, resistance, time required for movement, and swing load of the moving liquid. The flow paths can be extended in whole or in part in directions other than the X direction to have a liquid passage longer than the length in the X direction. The guide sections and flow paths can guide the liquid 8 to flow over a length longer than the straight-line distance of the cavity 5 in the X direction, and the movement time can be made longer than that of liquid moving linearly in the X direction. The guide section and flow path have protrusions or recesses on the inner surface of the tub body 1 from the wall surface 1a, and are provided with irregularities such as projections, plates, walls, grooves, holes, steps, depressions, tapered surfaces, cones, frustocones, passages, labyrinths, liquid reservoirs, waves, spiral flow paths, etc., tubes, narrowing or expanding tunnels, to bring the liquid 8 traveling in a straight line in the X direction into contact with the guide, guide it in a predetermined direction, divert it, obstruct its straight progress in the X direction, and limit the flow rate. For example, a spiral flow path has a spiral groove, wall, or passage that is inclined toward the tip side than in the Y direction, and guides the liquid 8, causing it to move toward the tip side while rotating spirally due to centrifugal force. The flow rate of the liquid 8 can be increased by increasing the width and depth of the flow path. By making the flow path shallow, the overflowing liquid 8 can proceed in the X direction, while the liquid 8 flowing through the flow path can be guided, diverted, and moved toward the tip side with a time difference. Furthermore, the flow path can be configured to allow liquid 8 to flow more easily in a specific direction than in other directions. For example, the X-direction toward the tip can be made to allow flow more easily than the rear end, making backflow less likely. In addition, the irregularities provided on the wall surface 1a can reinforce the wall surface 1a.

[0033] The bat body 1 in Figures 1 and 5 has one hollow cavity 5, but multiple cavities can be provided. Multiple cavities 5 can be arranged with equal width and shape, divided on both sides, in parallel or symmetrical positions, and filled with the same amount of liquid to achieve good balance without weight unevenness. Multiple cavities 5 can be arranged adjacent to each other, side by side, or spaced apart, and can hold the same or different types of liquids 8, viscosity, specific gravity, volume, and color. Multiple cavities 5 can each be extended in the X direction or in other directions, and partitions can be provided to divide the hollow portions, forming a predetermined shape, position, and number of cavities 5. The partitions act as reinforcement parts 7, improving strength. In addition, liquids 8 can be poured into multiple containers. The cavities 5 can be provided along the wall surface 1a, and can be provided in the region including the central axis inside the cylinder of the bat body 1, and the central axis of the cavities 5 can be positioned in the center or eccentrically, in terms of shape and orientation.

[0034] Liquid 8 can include water (including tap water and distilled water) or other liquids, such as oil. Water is safe and easy to handle and use, easy to procure, pour, and drain, inexpensive, can instantly and accurately reflect liquid movement due to centrifugal force, and is easy to color. Oil can adjust the speed and degree of liquid movement depending on its viscosity and type. One or more liquids 8 can be used. For example, viscous oil can slow down the speed of liquid movement compared to water alone. Multiple liquids that do not mix, such as water and oil, can be used to adjust the speed of liquid movement and make centrifugal force visible. Multiple liquids that mix, dissolve, or do not dissolve, or multiple liquids with different densities can also be used. Liquid 8 can include colored liquids. Colored liquids can be colored with colorants, such as red, yellow, blue, green, pink, or fluorescent colors, making liquid movement easier to recognize than colorless or transparent liquids. Liquid 8 can contain powders or granules. The granular particles suspended in the liquid 8 reflect light transmitted through the light-transmitting section 11 and light irradiated from the light source, making it easier to recognize the movement of the liquid 8. The tub 101 can have a light source that irradiates light onto the moving liquid 8. The light source can be, for example, an LED light, and can be placed inside or outside the tub 101, for example, irradiating light into the cavity 5 from the head section 4 and grip section 2. The light source can also be placed on the inner surface of the tub body section 1, or it can irradiate while suspended in or on the liquid surface. The light source can be made easier to recognize the movement of the liquid by mixing suspended material that reflects and diffuses light with the liquid 8, and by providing a reflective surface and reflector inside the cavity 5.

[0035] The amount of liquid 8 is appropriately determined according to the volume of the cavity 5 and the range of movement of the liquid 8, and can be, for example, 100 mL to 2 L, preferably 200 mL to 1 L. The amount of liquid 8 can be, for example, 10% to 70% of the volume inside the cavity 5, preferably 10% to 50%, and more preferably 10% to 40%. The cavity 5 is not completely filled with liquid 8, but has a non-liquid portion without liquid 8, which allows for smooth liquid movement by centrifugal force, and if the amount is too small, the liquid movement is difficult to feel and see. In addition, the amount of liquid 8 can be changed and adjusted by changing the mass of the tub 101 including the liquid 8. The non-liquid portion can be filled with gas. The gas can be a mixture of multiple types of gases such as air, or it can be a specific gas such as nitrogen or helium. In addition, the non-liquid portion can be at the same pressure as atmospheric pressure, or it can be filled with a gas at a pressure lower or higher than atmospheric pressure. By keeping the mass of liquid 8 less than or equal to the mass of the bat 101 other than liquid 8, the effects and load from the mass and movement of the liquid can be reduced, thereby improving the effectiveness and efficiency of swing practice. (Visibility section 10)

[0036] The bat body 1 has a viewing section 10 that allows the liquid 8 inside the hollow section 5 to be seen from the outside. The viewing section 10 makes the liquid 8, which moves towards the tip side (tip hollow section 6) on the head section 4 side due to centrifugal force during the swing, visible from the outside. The viewing section 10 has a light-transmitting section 11 (translucency). Light-transmitting means that light is transmitted to a degree that the movement of the liquid can be seen, and includes transparent and translucent materials. The viewing section 10 is provided on all or part of the wall surface 1a covering the hollow section 5 to visualize the movement of the liquid inside. The viewing section 10 can be made of any material that is light-transmitting and allows the movement of the liquid to be seen, such as FRP, polycarbonate, acrylic, fiberglass, carbon fiber reinforced plastic, resin such as polyvinyl chloride, and tempered glass, and lightweight materials are preferred.

[0037] The viewing unit 10 is positioned to allow the movement of the liquid due to centrifugal force to be visualized from the outside during the swing. Located behind the bat body 1, the viewing unit 10 allows the user to visualize the movement of the liquid and the liquid in the tip cavity 6 from behind the bat body 1 during the swing, from the initial top position to the approach, contact area, impact, and follow-through. The viewing unit 10, which allows the user to visualize the liquid 8 in the tip cavity 6 within a 30-degree range before and after impact, is useful for efficiently transferring centrifugal force to the ball. While swinging, the user can visualize the movement of the liquid from the viewing unit 10, visually recognize the centrifugal force of the swing, and feel the movement of the liquid more realistically. Using the visualized liquid movement as a guide, the user can practice while considering and confirming the correct swing, a swing with large centrifugal force, utilizing centrifugal force, transmission to the ball, pushing the ball, the movement and coordination of each part of the upper arm, arm, shoulder, upper body, and waist, the degree of relaxation and force application, the point of application, swing trajectory, forward movement, body axis rotation, and the height and position of the contact point. By repeatedly swinging, you can experiment, refine, improve, and practice proactively. This disclosure differentiates it from simply blindly repeating swings or from difficult practice that relies on unvisual sounds or collision sensations.

[0038] The viewing section 10 has a length (h) extending in the X direction and a width (w) in the Y direction. The length (h) is preferably 30 cm or more. If there are multiple viewing sections 10, the length (h) in the X direction is the distance between the two ends in the X direction. The viewing section 10 is, for example, 20% or more, preferably 40% or more, of the wall surface 1a covering the cavity 5. In Figure 1, the entire bat body 1 is a viewing section 10, and the viewing section 10 is provided between the head section 4 and the grip section 2, with a length (h). In Figure 1, the bat body 1 has no invisible parts that hide the movement of the liquid, and the movement of the liquid can be clearly seen from anywhere, regardless of posture. Furthermore, the bat body 1 has a cylindrical, translucent viewing section 10, which allows the movement of the liquid to be seen from any direction of 360 degrees, and light can be collected from any direction of 360 degrees, including the direction of sight and other directions such as the opposite direction of sight, illuminating the liquid 8 and making the movement of the liquid easier to see. The light-transmitting section 11 can be provided in places other than the viewing section 10, for example, in the head section 4, to capture light irradiated onto the liquid 8 inside the cavity 5. The grip section 2 can also have a viewing section 10 together with the internal cavity 5, so that the entire bat 101 can be a viewing section 10.

[0039] The viewing section 10 can be provided as one or more sections. The viewing section 10 can have reinforcing sections 7 arranged and stacked in the X direction, circumferential direction, Y direction, and other directions. For example, the viewing section 10 can be arranged with a partial opening in the cylindrical section 1A (Figure 2), narrow reinforcing sections 7 can be arranged vertically and horizontally between adjacent viewing sections 10 (Figure 3), and the viewing sections 10 and reinforcing sections 7 can be arranged alternately in close proximity (Figure 4), thereby improving the visibility and strength of the liquid movement. As illustrated in Figures 2 to 4, the viewing section 10 can be provided in a part of the bat body 1 and can be arranged including the cylindrical section 1A of the hitting section 3. The viewing section 10 can be extended in the X direction to increase the visibility range of the liquid movement 8. By providing the viewing section 10 in the hitting section 3, the impact with the ball can be closely observed during the swing, making it easier to transfer the force of the swing to the ball and preventing head-up. The hitting section 3 is provided with a viewing section 10 and a reinforcing section 7, allowing for visual confirmation of liquid movement while improving and ensuring strength. In particular, during actual batting practice, the aim is to focus on the ball and hit it with the core 3a of the hitting section 3 of the bat, so ball contact tends to concentrate on the core 3a and its surrounding area, and impact resistance can be efficiently improved by placing the reinforcing section 7 in that area. The viewing section 10 can be placed close to the hitting section 3 on the rear side of the bat body 1 during the swing, opposite to the point where the ball is contacted. Figure 7 shows that by placing the viewing section 10 on the opposite side (right side of the cylindrical 1A shown with two-line hatching) of the hitting section 3 that contacts the ball (left side of the cylindrical 1A shown with narrow hatching), and behind the direction of travel of the bat body 1, the liquid 8 can be seen from the rear side of the bat body 1 during the swing, and in particular the liquid 8 can be seen from the viewing section 10 before and after the impact point. By focusing on the impact with the ball, you can tuck your chin, prevent head-up, transfer power to the ball, and push the ball at impact. Furthermore, by looking at the viewing unit 10, you can naturally keep your eyes on the ball at the moment of impact. This allows you to be conscious of actual hitting even during practice swings, and incidentally has the effect of preventing head-up, stabilizing head position and gaze.

[0040] The bat body 1 in Figure 8 has an inlet 9a for injecting liquid 8 and an outlet 9b for discharging liquid 8. The inlet 9a and outlet 9b can be used interchangeably or provided separately. The inlet 9a and outlet 9b are positioned to communicate with the cavity 5, allowing the liquid 8 to be injected into and discharged from the cavity 5 to set and change the volume and mass of the liquid 8 inside. The inlet 9a and outlet 9b are provided on the head part 4 (Figure 8), as well as the grip end 2a and the bat body 1, and can be sealed, for example, by tightening screws or using a lid. The liquid 8 can be injected directly into the cavity 5 covered by the wall surface 1a, and a container or bag containing the injected and supplied liquid 8 can also be stored and placed inside the cavity 5. The inlet 9a and outlet 9b allow the volume of liquid 8 to be changed, thereby changing and adjusting the overall mass, balance, and center of gravity of the bat including the liquid 8. For example, the bat 101 can have its swing load and the effects of liquid movement reduced by decreasing the amount of liquid 8 and making it lighter. This allows even those with less strength, children, and women to swing without being overwhelmed by the weight, and it can be appropriately set and adjusted according to physical strength and skill. This makes swinging easier and allows for easier awareness of other aspects such as the sensation and visual perception of liquid movement, awareness of centrifugal force, body movement, coordination, and the bat's trajectory. On the other hand, increasing the amount of liquid 8 and making it heavier increases the swing load and slows down the swing, making liquid movement easier to feel, and also making it easier to recognize and be aware of body axis rotation, coordination of each part, and the swing trajectory.

[0041] The main body of the tub 1 in Figure 9 has a scale 12 on the viewing section 10 that indicates the volume and mass of the liquid 8. The scale 12 can indicate the volume and mass of the liquid 8 in the cavity 5 and the total mass of the tub 101 when the main body of the tub 1 is in a predetermined position, such as a vertical position. By injecting and discharging the liquid 8 based on the scale 12 and adjusting the volume, the mass can be easily adjusted to a predetermined level without measuring with a mass scale. The scale 12 can be placed on the viewing section 10 or elsewhere. The tub 101 may also have a liquid storage section for storing liquid and adding / removing it from the cavity 5. The liquid storage section expands the adjustment range of the tub's mass, balance, and center of gravity, and allows adjustment of the volume of liquid 8 in the cavity 5.

[0042] Furthermore, for example, the bat 101 (bat body 1) can be made extendable, detachable, extendable, and disassembled, allowing for adjustment of length, thickness, and shape, and convenient storage. Depending on the application, such as for practice swings or batting practice, the reinforcement part 7 can be attached to the hitting part 3 or the contact part, the bat body 1 can be replaced, and weights can be attached to adjust the swing load. In addition, the bat body 1, in addition to the visible part 10, can be provided with bumps, planes, lines, colors, markings, arrows, etc. on its outer surface to indicate the tip cavity 6, making it easier to recognize the position, direction, and timing of the liquid 8's movement, and can also produce the sound of the swing cutting through the air, making it easier to grasp and recognize the swing trajectory, angle, direction, rotation, impact, and wrist flick timing, thus improving functionality and design. The bat body 1 and / or grip part 2 may also have a rod-shaped section.

[0043] The bat 101 can be provided with one or more reinforcing sections 7. The reinforcing sections 7 can improve strength, durability, and impact resistance during actual hitting. The degree of reinforcement and the flex of the bat 101 can be adjusted by the thickness, shape, material, arrangement, and number of the reinforcing sections 7. The wall surface 1a itself can be made into a reinforcing section 7. For example, the reinforcing sections 7 can make the wall surface 1a thicker, be laminated and connected to the wall surface 1a, and can be arranged continuously or spaced along the wall surface 1a in the form of ribs, plates, bumps, grooves, steps, L-shapes, T-shapes, rings, cylinders, three-dimensional shapes, spiral shapes, etc. The reinforcing sections 7 can be arranged on the entire or partially outer surface and / or inner surface of the wall surface 1a of the bat body 1. Reinforcing sections 7 provided on the outer surface of the wall surface 1a are effective in improving impact resistance, for example, in the hitting area 3 and its vicinity. Reinforcing sections 7 on the inner side can improve strength without changing the outer shape or size. The reinforcing portion 7 on the inner side extends in the X and Y directions, and can effectively reinforce by bracing the inner diameter, intersecting, and connecting and bridging opposing surfaces in circular (disk), ring (Figure 5), cylindrical, or cross-shaped (Figure 6) forms. Furthermore, the reinforcing portion 7 on the inner side has gaps that allow the liquid 8 to pass through (Figures 5 and 6), enabling reinforcement without hindering the movement of the liquid within the cavity 5, and also reducing weight.

[0044] The reinforcing part 7 can be provided according to parts that require reinforcement, such as the hitting part 3, the visual recognition part 10, the base of the bat main body part 1, the connecting part with the grip part 31, and their peripheries and surroundings, so as to efficiently improve the strength of each part and the whole. The reinforcing part 7 that does not impede visibility as much as possible can reinforce while closing the visual recognition part 10. For example, the reinforcing part 7 can be made transparent or translucent with light transmissivity (Figs. 1 and 2), and narrow-width reinforcing parts 7 can be arranged in between (Figs. 3 and 4). In the bat main body part 1 (cylindrical 1A) of Fig. 7, the reinforcing part 7 is provided at the hitting part 3 on the left side (hatching with narrow intervals) that contacts the ball to improve the strength of the hitting part 3, and the visual recognition part 10 is provided on the opposite side, the right side (two-line hatching) other than the hitting part 3, so that both strength improvement and visibility assurance can be achieved. The reinforcing part 7 shall be appropriately provided in consideration of factors such as mass, material, arrangement, degree of reinforcement, and weight balance of the bat. The reinforcing part 7 can be detachably attached to the bat main body part 1. For example, a cylindrical, arc-shaped, or belt-shaped reinforcing part 7 can be attached to the hitting part 3 to reduce contact impact. It should be noted that this disclosure does not specify the shape, size, number, material, structure, etc. of the reinforcing part 7. The bat main body part 1 is provided with an elastic body having elasticity, viscosity, plasticity, such as rubber, plastic, or foam, at the hitting part 3, etc., so as to absorb impact and vibration. The elastic body can also be detachably attached. (Embodiment 2)

[0045] The bat can have one or more cylindrical shapes 1A, wholly or partially. Figs. 11 to 15 illustrate the swing training tool 200 (bats 201, 202) according to Embodiment 2. The bat 201 in Figs. 11 and 12 has a plurality of wall surfaces 1a, and the outer cylindrical 1B and / or the inner cylindrical 1C reinforce each other, and the outer cylindrical 1B and the inner cylindrical 1C can be made close to and connected to each other to efficiently improve the strength. The bat 201 has a bat main body part 1 having an outer cylindrical 1B and an inner cylindrical 1C arranged inside the outer cylindrical 1B.

[0046] The bat can have the cavity 5 disposed inside the outer cylindrical portion 1B and / or inside the inner cylindrical portion 1C. The bat 201 in Fig. 12 has the cavity 5 provided in the hollow portion inside the inner cylindrical portion 1C. The outer cylindrical portion 1B and the inner cylindrical portion 1C can visually recognize the liquid movement as the visual recognition portion 10 entirely or partially. The cavity 5 of the bat 201 is smaller than that of the bat 101, and the quantity and mass of the liquid 8 can be reduced, achieving weight reduction. The cavity 5 is formed including the central axis of the bat main body portion 1. The ratio of the length in the longitudinal direction (X direction) to the inner diameter (Y direction) of the cavity 5 can be increased, enabling a stronger feeling of centrifugal force due to swinging and liquid movement, and allowing the recognition of centrifugal force in conjunction with vision.

[0047] The bat 202 in Fig. 13 has the cavity 5 provided between the outer cylindrical portion 1B and the inner cylindrical portion 1C. The cavity 5 of the bat 202 is disposed close to the visual recognition portion 10 and has a long movement distance of the liquid 8 extending in the X direction, facilitating the visual recognition of liquid movement. Similar to Fig. 12, the cavity 5 of the bat 202 is smaller than that of the bat 101, and the quantity and mass of the liquid 8 can be reduced. The maximum interval of the cavity 5 between the outer cylindrical portion 1B and the inner cylindrical portion 1C is preferably 1 / 10 or less of the length of the cavity 5. The intervals between the outer cylindrical portion 1B and the inner cylindrical portion 1C can be the same or different. This cavity 5 can be annularly arranged over the entire circumference (central angle of 360 degrees), or partially arranged in an arc shape or a fan shape, and a width with a central angle of 45 degrees or more is preferred. The inner cylindrical portion 1C can be arranged concentrically (Figs. 12 to 14) or eccentrically (Fig. 15) with the outer cylindrical portion 1B.

[0048] The inner cylindrical shape 1C can be in partial (Figure 15) or circumferential contact with the inner surface of the outer cylindrical shape 1B, or it can be positioned at a distance from it. The inner diameter of the inner cylindrical shape 1C can be, for example, 30% to 90% of the inner diameter of the outer cylindrical shape 1B. By increasing the inner diameter of the inner cylindrical shape 1C, the inner cylindrical shape 1C can be positioned closer to the outer cylindrical shape 1B, thereby improving strength. By decreasing the inner diameter of the inner cylindrical shape 1C, the cavity 5 between the outer cylindrical shape 1B and the inner cylindrical shape 1C can be enlarged. The maximum distance between the inner surface of the outer cylindrical shape 1B and the outer surface of the inner cylindrical shape 1C can be, for example, 1 cm to 5 cm. A shorter distance (d) can improve strength and enlarge the cavity 5 inside the inner cylindrical shape 1C, while a longer distance (d) can enlarge the cavity 5 between the outer cylindrical shape 1B and the inner cylindrical shape 1C. This range is preferable in order to achieve both efficient strength improvement and ease of visualizing the liquid movement in the viewing section 10. The inner cylindrical section 1C and the outer cylindrical section 1B are connected and reinforce each other. Figure 11 shows that both ends of the inner cylindrical section 1C are supported and connected to the head section 4 and the grip section 2. The head section 4 has a flat surface as well as irregularities such as a mortar shape, which allows the inner cylindrical section 1C to be connected. The bat 201 can be further strengthened and support the inner cylindrical section 1C by providing a reinforcing section 7 that directly connects the inner surface of the outer cylindrical section 1B to the outer surface of the inner cylindrical section 1C (Figure 14). For example, the reinforcing section 7 on the back of the hitting section 3 can support the hitting section 3, improving impact resistance and strength. The reinforcing section 7 can also be used as a partition, guide section, or flow path, allowing for balanced movement of liquid.

[0049] The inner cylindrical portion 1C can have the same (similar) or different (dissimilar) shape as the outer cylindrical portion 1B. The inner surface of the bat body portion 1 covering the cavity portion 5 can be the same or different from the outer surface of the bat body portion 1. The inner surface can be a smooth surface such as a curved surface or a flat surface, and can also have irregular parts such as walls, plates, ribs, protrusions, holes, spirals, or labyrinths. The irregular parts serve as reinforcements to improve the strength of the bat body portion 1 and partially hinder the smooth movement of the liquid 8, thereby adjusting the liquid movement time and centrifugal force load.

[0050] The vat can enjoy the advantages of both by having cavities 5 both inside the inner cylindrical shape 1C and between the outer cylindrical shape 1B and the inner cylindrical shape 1C. Furthermore, the vat can also have three or more cylindrical shapes 1A. One or more cavities 5 can be provided between the multiple cylindrical shapes 1A, and / or inside the innermost cylindrical shape 1A. Each of the multiple cavities 5 can move the liquid 8 inside by centrifugal force, and different movement paths, different viscosity liquids 8, different movement times, and different movement patterns can be achieved. (Embodiment 3)

[0051] Figure 16 illustrates a golf swing training aid 300 (club 300A) according to Embodiment 3. The club 300A comprises a shaft portion 301 corresponding to the main body portion 1, a head portion 304 at the front end connected to the shaft portion 301, and a grip portion 302 at the rear end for gripping. The shaft portion 301 has a hollow portion 305 (first hollow portion 305A) inside which liquid can move, and a viewing portion 310 that allows the liquid 8 moving inside the hollow portion 305 during the swing to be seen from the outside. As shown in Figures 16 and 17, the head portion 304 also has a hollow portion 305 (second hollow portion 305B) inside which liquid can move, and the second hollow portion 305B can communicate with the first hollow portion 305A. The club 300A has a shape, length, weight balance, etc., similar to a golf club (wood, iron), allowing for swing practice that is similar to that of a golf club. As shown in Figure 17, in a golf swing, the swing training aid 300 starts at address, takes a backswing to a top position over one shoulder, then goes downswing, adds body rotation, passes through impact, follows through, and reaches a finish position over the other shoulder. At the top position, the club 300A has liquid 8 in the lower part of the cavity 305 (the grip portion 302 side of the first cavity 305A). As the head portion 304 is swung down in a large arc during the downswing, centrifugal force and gravity cause the liquid to move towards the tip of the shaft portion 301 and towards the second cavity portion 305B. With the liquid 8 moved into the second cavity portion 305B at the tip of the cavity portion 305, the head portion 304 passes the impact position near the ground and proceeds into the follow-through. The club 300A in Figure 16 allows for easy experience of centrifugal force during a swing by allowing liquid to move through a long cavity 305 where the first cavity 305A and the second cavity 305B are connected. The liquid movement from the viewing section 310 is also easily visible, enabling swing practice that is mindful of centrifugal force. The club 300A can be the same length as or different from the club size, for example, between 50 cm and 1.5 m, and between 1.0 m and 1.3 m for a driver. The descriptions of each embodiment are applicable to other embodiments as long as they do not contradict or conflict with each other, and can be modified as appropriate depending on the embodiment.

[0052] The shaft portion 301 connects the head portion 304 and the grip portion 302. The shaft portion 301 can have the same or different outer diameter as the grip portion 302, and can decrease or increase from the connection portion with the grip portion 302 toward the head portion 304. The shaft portion 301 in Figure 16 has an outer diameter greater than or equal to the narrowest part of the grip portion 302, making the first cavity portion 305A and the viewing portion 310 larger, increasing the liquid volume, and making the liquid movement easier to see. The shaft portion 301 is sized and shaped to be visible from the viewing portion 310 during the swing, and its outer diameter can be, for example, 5 mm to 5 cm, preferably 1 cm to 4 cm. The shaft portion 301 is, for example, within 4 times, preferably 3 times or less, the narrowest part of the grip portion 302. The wall surface 1a of the cavity portion 305 can adjust the liquid movement time and centrifugal force load with a guide portion, flow path, etc., as in Embodiment 1.

[0053] The head portion 304 can be a three-dimensional shape that mimics the head shape of a golf club (wood, iron). In Figure 16, the head portion 304 has a head shape similar to that of a driver (wood), but it can be an iron shape, or other shapes other than a club head, such as a cone (cone, pyramidal), cylindrical, spherical, or plate-shaped. By having a three-dimensional shape with a larger outer diameter than the shaft portion 304, the volume of the second cavity portion 305B can be increased. Alternatively, the head portion 304 can be a cap or lid that closes the cavity portion 305 without having a three-dimensional shape.

[0054] The club 300A can have a transparent viewing section 310, either entirely or partially, and a hollow section 305, either entirely or partially. The club 300A illustrated in Figure 16 has a transparent viewing section 310 in both the shaft section 301 and the head section 304, allowing the liquid 8 (movement) inside the hollow section 305 to be visible regardless of position, orientation, or angle. The grip section 302 can also be a transparent viewing section, and the hollow section 305 can extend to the grip section 302.

[0055] The club 300A has interchangeable parts. The head section 304 has a connecting section that allows it to be replaced with different shapes such as wood (Figure 16), iron, and a closure cover, thereby changing the weight of the tip, the mass balance, and the width and presence or absence of the tip cavity 6. The club 300A (shaft section 301) is extendable, detachable, and can be extended to adjust its length.

[0056] This disclosure can be suitably used as a swing training aid that allows for the visual recognition of the centrifugal force of the swing.

[0057] 100, 200, 300…Swing training aids 101, 201, 202…Bat 1…Bat body (body) 1a…Wall surface 1A…Cylindrical 1B…Outer cylindrical 1C…Inner cylindrical 2…Grip part 2a…Grip end 3…Hitting part 3a…Core part 4…Head part 5, 51, 52…Hollow part 6…Tip hollow part 7…Reinforcement part 8…Liquid 9a…Inlet 9b…Outlet 10…Visibility part 11…Translucent part 12…Scale 300A…Club 301…Shaft part (body) 302…Grip part 304…Head part 305…Hollow part 305A…First hollow part 305B…Second hollow part 310…Visibility part

Claims

1. A swing training tool comprising a main body, a head portion connected to the main body at the front end, and a grip portion at the rear end for holding, wherein the main body has a hollow portion containing a liquid that can move inside, and a viewing portion that allows the liquid moving inside the hollow portion during a swing to be seen from the outside.

2. A swing training aid according to claim 1, wherein 40% or more of the outer surface of the main body is the visible portion.

3. A swing training device according to claim 1, wherein 80% or more of the outer surface of the main body is the visible portion.

4. A swing training aid according to claim 1, wherein the entire outer surface of the main body is the visible portion.

5. A swing training device according to claim 1, wherein the viewing portion is located on the rear side of the main body.

6. A swing training device according to claim 1, wherein the liquid is water or a liquid containing oil.

7. A swing training device according to claim 1, wherein the liquid comprises a colored liquid.

8. A swing training device according to claim 1, wherein the liquid and gas are present in the cavity.

9. A swing training aid according to claim 1, wherein the main body comprises an outer cylindrical shape and an inner cylindrical shape disposed within the outer cylindrical shape, and the inner cylindrical shape comprises the hollow portion.

10. A swing training aid according to claim 1, wherein the main body portion has an outer cylindrical shape and an inner cylindrical shape disposed inside the outer cylindrical shape, and the main body portion has the cavity portion between the inner surface of the outer cylindrical shape and the outer surface of the inner cylindrical shape.

11. A swing training device according to claim 1, further comprising an injection port for injecting the liquid into the hollow portion.

12. A swing training device according to any one of claims 1 to 11, wherein the liquid is in an amount of 10% or more and 70% or less of the volume of the cavity.

13. A swing training device according to claim 1, wherein the main body is a bat body, and the bat body has a viewing portion that allows the liquid moving inside the cavity during a swing to be seen from the outside.

14. A swing training device according to claim 1, wherein the main body is a shaft, the hollow portion has a first hollow portion within the shaft and a second hollow portion within the head portion that communicates with the first hollow portion, and the swing training device has a viewing portion that allows the liquid moving within the hollow portion to be seen from the outside during a swing.

Images