COMPOSITE BAT STRUCTURE

THE FILED OF THE INVENTION

The present invention relates to an improved composite type bat structure. In particular, combination of a barrel portion of a metal cylindrical body and a grip portion of FRP makes it possible to move a gravity center of the barrel portion close to a center of percussion of the barrel portion, thereby giving a maximum impact energy to the center of percussion while the grip portion for locking the bottom hand as a palm grip makes it possible to give a maximum of angular velocity to the bat swing.

BACKGROUND ART

So far, there has been proposed the Patent document 1 wherein a barrel portion of a metal and a grip portion of a metal are connected with a polymeric adhesive (elastomer) having a smaller elastic coefficient than the grip portion and the barrel portion, whereby a hitting impact to the player arm caused by an off-center hitting could be released. However, interposing of the bonding member, although it can alleviate the impact from the barrel portion to the grip portion, causes a fault in the energy transfer to the barrel portion from the grip portion. On the other hand, in the light of the energy transfer failure, another bat structure has been proposed in the Patent document 2, wherein a rigid connection is provided between the barrel portion and the grip portion. Therefore, there have been proposed two different kinds of connecting manner between the grip portion for giving a hitting swing energy and the metal barrel portion for having a center of percussion of the bat; the former one is a vibration damping format by using a vibration cushioning material as the connecting member (the Patent Document 1), while the other is a rigid connection format as the connecting member (the Patent Document 2).

On the other hand, it has been recently recognized that the bat grip structure becomes important as a batting style to maximize the bat velocity (Non-Patent Document 1), so that a variety of grip structures have been proposed (the Patent Documents 3 and 4). In the Patent document 3 (Giant Patent), there is proposed combination of a grip portion having a substantially circular cross-section with a tilt angle portion and a knob-like grip end wherein the lower edge of the grip end is gently curved and formed as a face for supporting a short palm muscle and a little finger abductor muscle of the bottom hand, thereby improving the grip strength during the bat swing. In the Patent document 4 (Bruse Patent), the grip portion is provided with a non-circular cross-section as well as an asymmetrical flare-shaped portion at the end of the grip portion, thereby realizing a palm grip with the bottom hand.

However, the proposed grip structure having not a circular cross section, but a non-circular cross-section as well as a lot of grip end variants such as an atypical formation, cause it difficult to produce a bat having a barrel portion integrally with the grip portion, thereby proposing a good connecting formation for the barrel portion with the grip portion (the Patent Document 5).

Under such circumstances, there has been proposed the metal bat because of a larger sweet spot and a closer position to the grip side than that of the wooden ones, so that the metal bat is good for the beginners to do a hitting exercise and to have a good durability as compared to the wooden ones. So, the metal bat has been recommended for players in a junior high school and a senior high school. From the aspect of the striking efficiency, the barrel portion as the striking part should be made of a metal having a high coefficient of reflection. On the other hand, the lighter grip portion made of the materials such as FRP has been proposed to bring a center of gravity of bat closer to the center of percussion of the bat than in case of the metal bat grip, thereby making the impact energy being acted on the center of percussion rather than on the center of the gravity. In the light of this, it has been found that a composite type bat structure can be made by heterogeneous connections for the barrel portion made of a metal and a grip portion made of FRP and so on.

(The Need for a Palm Grip with Bottom Hand)

On the other hand, realization of the correct bat swing is depending on how to grip the bat grip portion by the bottom hand. Usually, in case of right-handed players, the grip should be done in a manner that the second joint of the fingers of their right hand (the top hand) comes into a portion between the second joint and the base joint of the finger of the left hand (the bottom hand). This is the most orthodox gripping manner, and both back faces of the hands are parallel to each other. This grip manner makes a three right angled relationship between both the arms and the bat in the “top” of the take-back, wherein a plane formed from the shoulder of the bottom hand through the arm to the bat becomes corresponding to a bat swing plane toward the ball, that is, the swing along the plane can help “bat swing out from the inside” (non-Patent Document 1). Both the gripping strength of bat and the control performance of bat require a palm grip of lower region of the bat with the bottom hand as well as a finger grip of upper region with the top hand. In this grip position, the second joint of the finger of the bottom hand comes to a portion between the second joint and the base joint of the finger of the top hand. On the other hand, the down swing by the players, requires not only the palm grip with the bottom hand, but also the palm grip with the top hand, at least a palm area corresponding to the middle finger, the ring finger and the little finger. In case of the softball, the grip is similar to the baseball grip for the down swing, so that the palm grip with not only the bottom hand, but also at least the middle finger, the ring finger and the little finger of the top hand, are required for strong hitting. Therefore, in the “top” of the take-back during the swing, the above mentioned three right angled relationship between both the arms and the bat is required to make a plane formed from the shoulder of the bottom hand through the arm to the bat, which plane corresponds to a bat swing plane toward the ball. In the light of this, firstly it is proposed to provide a gripping structure for making a palm grip by the bottom hand and keeping the three right angled relationship between both the arms and the bat. For implementing the gripping structure provided with the above function, it is proposed that the bottom grip portion should be provided with a cross-section of approximate oval from the grip end to the center of grip as well as the locking structure should be positioned at the grip end for pressing the bottom hand toward the thumb side and provided with laterally swollen portions (Japanese Otafuku shape) at one side or preferably both sides of the grip end.

THE PRIOR ART LITERATURE

Patent document 1: Japanese Patent No. 3529966 Publication

Patent document 2: Japanese Patent No. 4294982 Publication

Patent document 3: U.S. Pat. No. 7,744,497 Specification

Patent document 4: U.S. Pat. No. 7,878,930 Specification

Patent document 5: Japanese Utility Model Registration No. 31177460

Non-Patent document 1: “Batting mechanism Book” (theory ed.) Baseball magazine published by Ken Maeda,

THE SUMMARY OF THE INVENTION

Problems to be solved by the invention in view of this situation, the inventor thought it better that the grip portion of materials such as FRP facilitates the maximum angular velocity of the bat swing, while the barrel portion of the metals facilitates an excellent striking efficiency. However, in the joining manner between the grip portion and the metal barrel portion, there have been proposed two ways; one is the shock damping junction between the metal body part and the metal grip (Patent Document 1) while the other is the complete energy transfer rigid junction between the metal body part and the metal grip (Patent Document 2). Each joints has an advantage and disadvantage. The latter is better to improve the angular velocity of the metal barrel part, while the former is better to decrease an impact shock to swing with a palm grip of the bottom hand. As a result of the intensive studies, the present inventor has been found that the use of high strength and high elastic material having an intermediate property as a joint material for two different parts, one being a metal barrel portion and the other a FRP grip, could facilitate a maximum of angular velocity of the swing, as well as a release of the impact transmission to the grip portion from the barrel portion. Based on the above findings, we have completed the inventive bat structure wherein an impact vibration from the barrel portion of a metal can be transferred to the grip portion made of a FRP via the connecting parts having a high strength and high elasticity, whereby superior impact efficiency can be easily obtained.

Means to Solve the Problem

The present invention is to provide a composite type bat structure which comprises a barrel portion for forming a center of percussion, a grip portion having a grip end, a throat portion extending from the barrel portion to the grip portion, the barrel portion and the grip portion being connected with a connection member for forming the throat portion so as to form a three-piece composite type bat, wherein the barrel portion is made from a hollow metal cylindrical body having a higher specific gravity than the grip portion, and the distal end opening of the barrel portion is closed by the cap portion, preferably if the cap is added with a predetermined weight, the center of gravity positioned at the lower side of the barrel portion can be shifted to the upper side of the barrel portion. The grip portion is made from a FRP having a specific gravity lighter than the metal barrel portion, whereby the center of gravity can be shifted more to the distal end of the barrel portion. Further, the grip portion is provided with a function of locking the bottom hand, and the connecting member is integrated with extension of the grip portion to make the throat portion, whereby the connecting portion becomes a property of vibration damping factor lower than the grip portion, and larger than the barrel portion to provide a vibration attenuation rate parts for connecting the rear end of the barrel portion with the tip of the grip portion. In a preferred embodiment, a barrel portion is made from a hollow metal cylindrical body while a grip portion is made from a FRP. The grip portion comprises a grip part and a grip end parts respectively, and the grip end part is connected to the grip part to form a locking means for the bottom hand. The barrel portion and the grip portion can be connected with a connection member for forming the throat portion so as to form a three-piece composite type bat. In a preferred embodiment, the three-piece composite type bat may be formed as a vibration damping means made from a material selected from the high strength and high elastic resins consisting of a para-aramid resin (Kepler), an ultrahigh molecular weight polyethylene resin, a PAR resin (poly-arylate resin), a PBO resin, and a Carbon resin, thereby being constructed as a mild damping means for the grip portion to provide the throat portion having a proper property connecting the barrel portion with the grip portion. Further, the barrel portion lower end can be constructed to engage a mating recess on a lower outer periphery of the connecting part, while the grip portion upper end is constructed to engage through an outer fitting convex portion into an upper inner peripheral mating recess in the connecting part. The metal barrel portion for forming a center of percussion can be mainly made of aluminum or an aluminum alloy, while the grip portion can be mainly made of FRP selected from the glass fiber FRP and the carbon fiber FRP, so that the throat portion extending from the barrel portion to the grip portion may be selected in a decreased order of the shock damping coefficient from the metal through that of Kepler to the FRP grip.

The above composite type bat structure made from the metal barrel portion and the FRP grip portion can attenuate the impact vibration of the barrel portion while suppressing an extreme tilting by the connection part made of high strength and high elastic resin grip, so that not only to relieve discomfort due to off-center hitting, but also to let the center of gravity moved close to the center of percussion by adaptation of the metal cylinder body make it possible to enhance the striking efficiency.

Further, in a preferred embodiment of the present invention, separate production of the grip portion and the grip end makes it possible to produce them as different parts and to integrate them into a body, whereby it is easy to form the grip portion for performing a palm grip with the bottom hand. So, in the first and second modification of the present invention for teaching the palm grip with the bottom hand and the finger grip with the top hand at the same time, the locking structure makes it possible to prevent the bottom hand from escaping out of the grip end, especially at least the little finger tip side and the third joint of the bottom hand. Further, addition of reinforcing portion can be engaged with the little finger tip and/or the palm side of the little finger to avoid their escaping out of the grip end during swinging. Furthermore, according to the third modification of the present invention, there are provided an approximately oval cross-section of the lower grip perpendicular to the bat axis from the end of the grip end to the grip center, as well as an oval cross-section of the upper grip perpendicular to the bat axis from the grip center to at least the three fingers of the upper hand and a circular cross-section of the remaining grip portion, teach not only to a palm grip with the bottom hand, but also to another palm grip with the top hand while keeping excellent operability of the bat.

According to the present invention, at the top of the take-back position, the bat gripping manner can lead to make a three orthogonal angled relationship between the two arms, and each of the arms and bats in order to match the line from the bottom hand shoulder to the arm and the bat to a swing plane toward the ball, thereby realizing a swing along the line of the bottom hand like a batting from inside. The right angled relationship between the grip of the bottom hand and the line from the forearm to the bat can achieve the correct swing, which induce a behavior of bat swing like hitting a grip to improve the angular velocity of the bat swing.

In addition to forming the locking mechanism portion at the grip end, it is preferable to form an increased coefficient of friction of the grip on at least a central part of the grip portion wrapped by the palm of the bottom hand On the other hand, the upper region of the grip portion extending from the grip center to the throat portion, there is provided with a portion having an increased grip friction coefficient around the second joint of the top hand when the grip portion is gripped with the top hand, thereby realizing the palm grip with the bottom hand and the finger grip with the top hand with ease.

From mechanical consideration of the action with respect to the batting, as shown in FIG. 10, the bat comprises a barrel portion B of the largest and uniform diameter from the tip of the head H, a throat portion T of gradually reduced diameter from the barrel portion B and a grip portion G. The bat generally terminates with a grip end E (the bat science: http://www.mitsuwa-tiger.com/batmuseum). And, considering that the batting is an elastic collision, it is a proposition of batting that combined motions of gripping the bat in the grip portion G, drawing the bat, and swinging the bat with a maximum of angular velocity ω, can make the kinetic energy F=Iω represented by the product of the grip moment of inertia I and the angular velocity ω, onto the center of gravity G which was separated by a distance of (a) from the grip center Gc, whereby the kinetic energy F is given to hit the ball with a sweet point in the vicinity of the center of percussion P of the bat. In the above sweet point, the coefficient of repulsion can be represented by (V2−V0)/(V1−V2) and the maximum value can be obtained wherein V2 (the swing speed of the bat), V0 (the ball speed immediately after hitting) and V1 (the ball speed from the pitcher). So, from the first aspect of the present invention based on the striking proposition, there is provided a composite type bat structure by use of a first to a third embodiment of the grip structure to get the best swing with the maximum of angular velocity ω and to hit the ball at the bat sweet spot while providing a maximum moment of inertia I to the center of gravity C of the bat.

In other words, firstly, since to accomplish the bat swinging at the maximum angular velocity ω needs the player to have the three right angled relationships for “putting the bat outwardly from inside” when the grip structure capable of accomplishing the palm grip with at least the bottom hand is used to thereby accomplish the swinging “to swing the bat as if striking the grip”. For the “swinging of the bat as if striking the grip”, the grip structure is needed in which a right hand batter should grip and lock, under the palmar grip, with the back of the left hand oriented upwardly during the swinging, and exercise to urge the bat incident to rotation of the hip below such grip to thereby complete it (FIG. 3B). And, secondly, the bat swinging at the maximum angular velocity applies the inertia moment about the center of gravity and the product of the inertia moment and the bat swinging angular velocity ω is applied in the form of the kinetic energy F to the ball and, thus, the batting energies for the ball is assured and the elastic collision with this ball takes place at the sweet spot. The sweet spot referred to above is the point at which the high coefficient of restitution (FIG. 10) and the batting centroid referred to above is the immovable point at which, when the ball impinges upon the ball, it leads that the translational motion of the center of gravity of bat and the rotatory motion about the center of gravity are counterbalanced with each other, but consequent upon the availability of the batting energy most effective to the batting at the sweet spot at which the high coefficient of restitution can be obtained, and as a result that the batting is made at the first maximum angular velocity and at the second maximum batting energy, the maximized batting effect can be obtained.

According to the present invention, there is also provided a bat grip structure which includes a bat head H, a bat barrel portion B, a bat throat portion T, a bat grip portion G and a grip end E, characterized by the provision of 4) a gravitational center position changing structure for displaying the original position of a bat center of gravity C, which lies at the bat barrel portion B, in a batting centroid Pc direction by adding an additional weight ΔM to the bat head, the grip portion has a sectional shape perpendicular to the longitudinal axis of the bat, which shape is represented by a generally oval shape suited for gripping with a palm, in which when the grip center Gc is moved to Gc1, the batting centroid Pc is adjustable to Pc1 while securing the palm grip with the bottom hand is secured, and in that 2) the grip end is inclined forwards at an angle within the range of 20 to 30 relative to a plane perpendicular to the longitudinal axis of the bat, and has a lock structure capable of turning about the hand wrist of the bottom hand to urge towards a thumb side and the grip end flares laterally outwardly of an end inclined face over the generally oval section of the grip portion G, an outwardly bulged portion of an Japanese Otafuku shape engageable with a palm portion adjacent the little finger tip and/or the little finger third joint of the bottom hand is formed therein and the maximum moment Iω imposed on the center of gravity that is obtained at the maximum angular velocity ω brought about by the grip structure has a function of transmitting the batting centroid Pc˜Pc1.

According to the present invention, when by the effect of a weight ΔM added to the bat head H the bat center of gravity C, which lies in the bat barrel portion B, is moved from the original position in a direction towards the batting centroid P, the kinetic energy F applied to the pitch at the sweet spot located in the vicinity of the batting centroid is maximized and, also, by the effect of the locking structure formed from the grip end E to the grip G, the back of the hand then gripping the hand opposite to the dominant arm is locked and is oriented upwardly to invite the batting impact to make it possible to apply the maximum angular velocity to the bat swinging so as to “swing the bat as if striking the grip”. By the cumulative effects described above, the maximum batting efficiency can be obtained. Although the weight ΔM to be added to the bat head has to be chosen depending on the total weight of the bat, a range of 10 to 100 gr is preferred. Also, regardless of the gripping position at least the bottom hand is allowed to grip under the palmar grip and the grip structure designed to provide the maximum angular velocity and the center positions Gc and Gc1 at which the maximum angular velocity can be obtained are changed to change with the batting centroids Pc and Pc1 on one hand and the bat structure is provided with which any batter can select a proper batting system in reference to the change of the position of the center of gravity which is to be moved from the original position of the bat center of gravity C, located in the bat barrel portion B, in the direction of the batting centroid Pc by the effect of the weight ΔM added to the bat head H.

The Grip of the present invention is preferably made from FRP, which can be selected from the group consisting of PAN-based fiber FRP, Pitch-based fiber FRP, Glass fiber based FRP, Aramid fiber based FRP, Silicon carbide fiber based FRP and the like. The Grip G preferably comprises a grip part GP covered with a grip end part EP wherein the grip parts GP is designed to have a gradually reduced cylinder diameter from the throat portion. FIGS. 16A to 16C show the grip end portion wherein the grip parts GP is inserted into the grip end part EP in a manner of off centered to one side and then integrated by filling a foamed resin into the grip end part EP. FIGS. 17A-17C show a combination of the grip part GP and the grip end part EP wherein the lower end of FRP based grip part GP is inserted into the center of the grip end part E-1 and then integrated by filling a formed resin into the grip end part. FIGS. 18A to 18C-3a combination of FRP based cylindrical grip part GP and auxiliary grip parts G-1 and G-2 wherein the auxiliary grip part G1 is designed as a semi-cylindrical portion to grasp the lower part of the grip portion with bottom hand and the inclined part G-2 is designed to grasp the upper part of the grip portion with the upper hand while opening the index finger and thumb of the hand. Finally, the combined grip portion GP with auxiliary grip parts G-1 and G-2 can be integrated with end parts E-2 by filling a foamed resin into them.

The palm grip with the bottom hand can be assisted by increasing the coefficient of friction of a part of the grip portion, which friction part is preferred to surround a half of the lower surface area of the grip portion. At least, the central part area and its vicinity of the grip portion is enough to make the increased coefficient area of friction.

The length of the grip portion having an increased coefficient of friction should be matched to the length coated by a pine resin, which is described in the rule book of US Major League Baseball Committee.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a grip structure designed in accordance with a preferred embodiment of the present invention, which grip portion G includes a grip area of an oval sectional shape and a friction increasing area wrapped by band which contacts a palmar surface of the bottom hand with a grip end lying at an angle and having a bulged portion swelling outwardly to prevent the tip and the palm part under the third joint of the little finger from slipping out;

FIG. 2 is a perspective view showing the grip area being gripped, in which the bottom hand can be locked and the palm grip can be kept on the increased area of the friction coefficient;

FIG. 3A is a diagram showing the basic shape, as viewed from diagonally rearward, in which three right angles are depicted at top;

FIG. 3B is a diagram showing the basic shape, as viewed from rearward, in which three right angles are depicted at top;

FIGS. 4A to 4D are explanatory diagrams showing the sequence of batting out from inside in which the distance between the bat and a batter's shoulder and the right angular relationship between the bottom hand and the bat do not change from the condition shown in FIGS. 3A and 3B;

FIG. 5 illustrates a first modified form of the grip structure designed in accordance with the present invention, which has the grip end provided with a bulged portion swelling outwardly at the side of the little finger tip;

FIGS. 6A to 6C illustrate a second modified form of the grip structure designed in accordance with the present invention, which has the grip end provided with bulged portion swelling outwardly at both sides of the little finger tip and the palm under the little finger third joint;

FIGS. 7A to 7C illustrate a third modified form of the grip structure designed in accordance with the present invention, which has the grip end provided with bulged portion swelling outwardly at both sides of the little finger tip and the palm under the little finger third joint; in which (A) shows the grip end swelled outwardly and lower three fourths (¾) of the grip portion is formed to represent an oval sectional shape for contact with the palm and the grip end is formed with the locking mechanism. Cross-sections at line A-A, B-B and C-C of lower three fourths (¾) of the grip portion are oblong oval shapes which is varying to the circular sectional shape (line D-D) in a direction towards a sloped portion;

FIG. 8 is a perspective view showing the third modified form of the present invention, showing the manner in which the grip area is grasped by the bottom hand and the top hand and in which, although the bottom hand assumes a palmar grip, the top hand assumes a semi-palmar grip with the thumb and the index finger opened, to enable a firm grip to be accomplished during the down swinging and for women's soft ball games.

FIG. 9 is a perspective view showing only the grip portion of the bat designed in accordance with the third modification of the present invention, in which the grip end is of a design in which a lower end portion thereof coincides substantially with the grip contour and is inclined at an angle of 20, 25 or 30 relative to the vertical line lying perpendicular to the longitudinal axis of the bat while outer and left and right ends thereof are somewhat swelled outwardly from the perimeter of the grip portion of an oval sectional shape along the inclined surface in the grip end. The grip end forms the locking structure for the bottom hand while the left and right side ends of the grip end are so shaped as to avoid the drop-out of the palmar end below the little finger tip and the little finger third joint, thereby completing the structure for maintaining the bottom hand in a locked condition.

FIG. 10 is an explanatory diagram to show the function of the conventional bat.

FIG. 11 is a perspective view of the bat structure according to the present invention.

FIG. 12 is a longitudinal sectional view of FIG. 11.

FIG. 13A is a perspective view showing the grasped manner of the grip portion of FIG. 1.

FIG. 13B is a cross sectional view taken along the line B-B in FIG. 13A.

FIG. 13C is explanatory diagrams showing respective conditions of the left hand and the physical angle that are exhibited at the time of impact at the inside (1), the middle (2) and the outside (3) of a right-handed batter then gripping the bat in the manner shown in FIG. 13A.

FIG. 14 is an explanatory diagram showing movement of the center of percussion P toward P1 due to displacement of the center of gravity G to G1, brought about by addition of a weight to the head of the bat, under the relationship of a×b=a1× b1 wherein (a) is a distance from the grip center to the center of gravity and (b) is a distance from the center of the gravity to the center of the percussion.

FIG. 15A is a perspective view showing a connecting condition between the FRP grip G and the metal cylinder barrel portion B via a vibration damping joint part J comprising a high-elastic and high-strength resin. FIG. 15B is an enlarged perspective view of the joint part J. FIG. 15C is a cross-sectional view of the joint between the metal cylinder barrel portion B and the FRP grip G. FIG. 15D is a partially enlarged cross-sectional view (D) of FIG. 15C.

FIG. 16A is a sectional view showing the grip portion G of the first embodiment provided with a locking portion R for locking the bottom hand between the end part EP and the grip end E provided with four bulge parts. FIG. 16B is a side view of the grip portion G. FIG. 15C is a plan view of the grip portion G.

FIG. 17A is a sectional view showing the grip portion G of the second embodiment provided with a locking portion R for locking the bottom hand between the end part EP and the grip end E. FIG. 17B is a side view of the grip portion G provided with four bulge parts. FIG. 17C is a plan view of the grip portion G.

FIG. 18A is a sectional view showing the grip portion G of the third embodiment provided with a locking portion for locking the bottom hand between the grip portion G and the grip end E provided with four bulge parts for keeping a palm gripping with the bottom hand and the little finger to the middle finger of the top hand. FIG. 18B is a plane view of the grip end E. FIG. 18C is a side views (C-1, C-2 and C-3) showing various tilt angles (20, 25, 30°) at the grip end E.

BEST MODES FOR CARRYING OUT THE INVENTION
First Preferred Embodiment 1

Hereinafter a first preferred embodiment of the present invention will be discussed. Referring to FIG. 1, there is shown a side view of a baseball bat in its entirety, which bat includes a bat head H, a bat barrel portion B, a bat throat portion T, a bat grip portion G and a grip end E. The bat in its entirety is made of wood and, although an end face of the bat head represents a circular shape, a grip end face represents a Japanese Otafuku shape (a generally trochoidal shape) that is generally similar to the oval shape having its opposite sides bulged outwardly, and is so formed as to have the shape changing from an oval section at the grip area to an exact circle at the throat area on one side of the center of the bat grip area opposite to the bat barrel B. FIG. 2 is a perspective view showing the grip area being gripped, in which the bottom hand can be locked and the palm grip can be kept on the increased area of the friction coefficient.

In case of the composite type bat comprising a metal barrel portion and a FRP light grip portion, addition of predetermined weight ΔM to the bat head H, makes displacement of the center of gravity C of the bat from the original position, which lies at the bat barrel B, by a quantity Δa in a direction towards the batting centroid P (the center of Percussion), and, therefore, the kinetic energy F applied to the center of gravity increases as shown in FIG. 14.

On the other hand, the barrel portion B extends to the grip portion G through the throat portion T. The grip portion is provided with a generally oval shaped section extending to the grip end E which is provided with a curved angle α being formed on a grip surface on an outside with respect to a center axial line that extends in the lengthwise direction, thereby completing a locking structure R. As a result of that this locking portion R causes a left hand (bottom hand) of the right handed batter from a little finger side to a thumb side to be declined, the left hand wrist is urged counterclockwise to press, as shown by the arrow in FIG. 13A, thereby keeping the forearm of the bottom hand and the bat at a right angled relationship so that return of the back of the batter's left hand can be suppressed during the bat swinging and, also, bending of an elbow of the left hand is suppressed during the impact. Also, at a semi-perimetric portion of the grip portion then grasped by the palm of the bottom hand, the gripping coefficient of friction is increased. On the other hand, if in an upper region of the grip portion ranging from the grip center to the throat portion the coefficient of friction is so increased as to bring the second joint of a finger of the top hand in between the second joints of fingers of the bottom hand and the roots of the fingers thereof, the upper grip portion is grasped with the top hand under the finger grip (See FIG. 2) so that the back of the bottom hand and the back of the top hand come to be parallel to each other. This is a condition in which in order to match the right angled relationship between the forearm of the second bottom hand and the forearm of the top hand with the plane of swinging oriented towards a ball along a line from the shoulder to the arm and bat, the bat gripping creates three right angled relationships between both arms, between one of the arms and the bat and between the other of the arms and the bat, respectively, so as that those three right angled relationship can be utilized to accomplish a sort of swing “to put the bat out from inside” along the line of the bottom hand.

The three right angles referred to above includes 1) the right angle (FIG. 3A) between the forearm of the bottom hand and the bat (FIG. 3A), 2) the right angle between the forearm of the bottom hand and the forearm of the top hand (FIG. 3A), and 3) the right angle between the forearm of the top hand and the bat (FIG. 3B). Particularly to create the substantially right angled relationship between the forearm of the bottom hand and the bat when the bat is in the top position has extremely important implications and that is why the bat shown in FIGS. 4A to 4D is so close towards the shoulder tip (acromion) that no change between it and the shoulder tip happens totally during the swing and a substantially right angled grip is kept and rather rotating power of the swing in most conditions is drawn thereby. Accordingly, the motion of putting the bat out from inside in the swing can be accomplished. In contrast thereto, if the angle between the bottom hand and the bat is obtuse when the bat is held in “top”, that is, the forearm of the bottom hand and the bat cooperate to form the obtuse angle when the bat is held in “top”, even though the length of time from the start of bat swinging to impact will become small, the bat head opens on the side of a catcher from the beginning and, therefore, a sufficient distance of acceleration to the impact cannot be secured with the speed of movement of the bat head during the impact consequently failing to increase and, since the head is opened from the beginning, the bat head will quickly return under the outside pitch, constituting a cause of trick swinging. Accordingly, speaking firstly to maintain the substantially right angled relationship of the angle between the forearm of the bottom hand and the bat at the time the bat is held top, it will readily be seen that gripping a grip lower region with the bottom hand under the palmar grip is important.

Then, speaking secondly, the right angle delimited between the forearm of the bottom hand and the forearm of the top hand controls both the rotation of the upper body and the respective movements of those arms which occur during the batting action. The both arms thus changes with the rotatory movement of the upper body brought about by the scapular movement, rather than being moved accompanied by the movements of the forearms. Accordingly, movement of both forearms while intersecting at right angles to each other results in the movement of the upper body at the time of start of swinging to draw the bat by the rotatory action along the line of the bottom hand without changing the distance from acromion to acromion (FIGS. 4B and C), thereby creating the behavior “the motion of putting the bat out from inside”. The right angle between the forearm of the bottom hand and the forearm of the top hand realizes the palm grip with the bottom hand and addition to this the bat grip area is gripped by the top hand under the finger grip so that the second joint of fingers of the top hand may come in between the second joint of the fingers of the bottom hand and the root of the fingers of the top hand, whereby the hand back of the bottom hand becomes parallel to the hand back of the top hand and the line ranging from the shoulder to arm of the bottom hand and to the bat can be matched with the plane of swinging. This motion creates the behavior “of putting the bat out from inside”.

The grip structure in the bat referred to above may be constructed in various preferred embodiments shown in FIGS. 5A and 5C to FIGS. 7A to 7C. Accordingly, the little finger side of the bottom hand can grip firmly under a power grip without falling off from the grip end and the forearm of the bottom hand comes to be maintained at right angles to the longitudinal axis of the bat.

FIGS. 6A to 6C illustrate an improvement of the modification model shown in FIGS. 5A to 5C, which is so designed as to prevent the drop-out from the grip end on the palmar side of the bottom hand then under the power grip and as to maintain the power grip by the bottom hand. In other words, according to the second modification now under discussion, a curved portion is bulged not only in an upper portion in the vicinity of the grip end, but also in the intermediate peripheral edge along a contact portion for the little finger tip and a contact portion for the lower palm for the little finger third joint to thereby render the drop-out of the palmar end of the bottom hand from the grip end to be difficult. And the drop-out of the little finger side from the grip end is avoided to thereby increase the gripping force. The bat having the above described structure is shown in FIG. 6. FIG. 6A illustrates an end view showing the end face of the grip end having the locking structure formed therein while an area ranging from the upper peripheral edge of the semi-perimeter on the bottom hand to the intermediate peripheral edge is curved in a direction towards the grip area. This condition is shown in the end view of the end face shown in FIG. 6B and the cross-sectional views taken along the line A-A and the line B-B in FIG. 6C. In other words, the end view of FIGS. 6A and 6B together with the line A-A and the line B-B of FIG. 6C, show a condition wherein a first locking portion is formed in an upper peripheral edge on which the second joint area of the bottom hand rests with the wrist being locked having been somewhat cocked counterclockwise and also a second inclined portion is formed extending from the grip end to the grip area in an area ranging from the upper peripheral edge of the semi-perimeter on the bottom hand to the intermediate peripheral edge, thus, the back of the bottom hand is locked having been somewhat lifted counterclockwise from the little finger side towards the thrum side. Accordingly, the palmar side of the bottom hand can be gripped under the power grip firmly without falling out from the grip end and the forearm of the bottom hand can be maintained at right angles to the longitudinal axis of the bat.

As can readily be understand from the description made with reference to FIGS. 3A and 3B and FIGS. 4A to 4D, it is clear that the first necessary task is to enable gripping in which the angle between the forearm of the bottom hand and the bat is substantially right angles to each other at the time of the top position under the palmar grip with the bottom grip, and, secondly, it is important to grip the bat grip area under the finger grip with the top hand so that the finger second joint of the top hand can be brought in between the finger second joint and the finger root against the palmar grip of the bottom hand so that the forearm of the bottom hand and the forearm of the top hand may be right angled relative to each other. One of the objects of the present invention is to provide the grip structure effective to accomplish such a gripping as described above and is of a grip structure having, firstly, a region effective to increase the coefficient of friction necessary to accomplish such gripping as discussed above and, secondly, the gripping is accomplished under the right-angled relationship between the bottom grip and the bat.

The grip structure shown in FIGS. 7A-7C to 9 is such that, in the bat grip area, the bottom grip ranging at least from the grip end to the grip center has a generally oval sectional shape in a plane perpendicular to the bat longitudinal axis; a grip portion for the three fingers ranging at least from the middle finger to the little finger is rendered to represent a generally oval sectional shape in the plane perpendicular to the bat longitudinal axis; and a region transiting therefrom to the throat area includes the inclined area in which the oval sectional shape is transmitted to the circular section represented by the throat area. This lies in the bat grip structure of the type which the palm of the bottom hand is engaged with the grip end under the palmar grip and, on the other hand, the middle finger to the little finger of the top hand is gripped to achieve a controllable palmar grip and the bottom hand is displaced in a direction towards the bat head under the palmar grip while the top hand is also displaced to grip the bat from the inclined portion. With the bottom hand and the top hand gripped under the palmar grip, downswing can be readily exercised, the grip suitable for use in the women's soft ball game can be realized;

The locking structure according to this embodiment now under discussion is formed by causing either an upper end of the grip end to follow the finger pulp, wherein the grip end is bulged laterally outside so that the region from the upper end of the grip end to both opposite ends thereof may brought into contact with the grip end, or the palmar peripheral end below the little finger tip side of the grip end and the little finger of the bottom hand may be brought into contact with the grip end. For this reason, the grip end represents the Japanese Otafuku shape having laterally bulged portion at both sides with each corner portion inclined inwardly from the grip end so that the second joint of the bottom hand as well as the little finger tip side and the palmar end side can be reinforced to avoid slip separation thereof from the grip end. It is to be noted that the lower end of the grip end follows the contour of the bat and need not be bulged, but if the end grip is so shaped as to have an angle selected from the group consisting of 20, 25 and 30 degrees relative to the vertical line, the locking strength of the grip can be increased.

Also, the region operable to increase of the coefficient of friction in the grip area is formed in at least an intermediate portion and in the vicinity thereof of the semicircular portion of the bottom grip portion that is grasped by the palm of the bottom hand so that gripping of the grip lower region (bottom) can be facilitated under the palmar grip of the bottom hand. With respect to the top hand, the region operable to increase the coefficient of friction in the grip area may be formed in at least an intermediate portion and in the vicinity thereof of the semicircular portion of the grip that is gripped by the palm corresponding to the middle finger and the third finger so that gripping of the grip upper region can be facilitated under the palmar grip of the top hand.

Second Preferred Embodiment

Hereinafter, a second preferred embodiment of the present invention will be discussed in detail.

FIG. 11 is a side view showing the baseball bat in its entirety, which includes a bat head H, a bat barrel portion B, a bat throat portion T, a bat grip portion G and a grip end E.

The bat in its entirety is made of wood and, one of ten adjustment cap type heads M is added to the bat head H of a standard weight so that the weight added to the bat head may be adjusted to a value within the range of 10 to 100 grams. Although the end face of the bad head is circular, the grip is non-circular and the grip end is bulged laterally from the top to the both sides as Japanese Otafuku shape.

A predetermined weight ΔM is added to the bat head H. Thereby, the center of gravity C of the bat, which lies in the bat barrel portion, is displaced a distance Δa from the original position towards the batting centroid P (See FIG. 14). In contrast thereto, the batting centroid P does not virtually displace and, hence, the position of the sweet spot of the bat, which is located at a position adjacent the batting centroid with respect to the center of gravity C does not displace correspondingly. Therefore, since the kinetic energy F applied to the center of gravity C is increased by the distance Δa from the center Q of gripping by the quantity of displacement of the center of gravity of the parameter I (inertia moment), the kinetic energy is increased by a quantity Δa×ω even though the angular velocity ω does not change. Moreover, consequent upon approach of the center of gravity C towards the batting centroid P, it has been dynamically ascertained that the kinetic energy acting on the center of gravity C is so apt to affect the sweet spot, so that the kinetic energy applied to the ball by hitting the sweet spot may be assuredly increased.

On the other hand, the barrel portion B extends through the throat portion T to the grip portion G, and the grip portion G toward the grip end is provided with the non-circular sectional shape, for example, the oval sectional shape and an inclination angle α is formed in on an outer side of a grip end relative to the longitudinal axis of the bat. The locking portion R of the oval sectional shape render the left hand of the right-handed batter to grip with its little finger side to the thumb side inclined and with the left hand wrist being locked having been urged counterclockwise to thereby suppress the return of the back of the left hand during the bat swinging and also to suppress the bending of the left hand elbow during the impact. This leads to the action of “swinging the bat as if hitting with the grip” and brings about such a result as to increase the angular velocity of swinging of the bat. The angle of inclination a relative to a center line of a flared portion F is preferably increased with increase of the weight ΔM of the bat head. That is because, as the center of gravity displace towards the bat tip end, the back of the left hand during the bat swinging tends to return with the inertia force acting thereon.

As discussed above, when the right handed batter swings the bat accompanied by the rotation of the batter's physical body without returning the left hand palm and then hits the ball with the left arm elbow straightened steadily, the action “to swing the bat as if hitting the grip of the bat” can be accomplished and the maximum angular velocity that can be achieved by such batter can be exhibited. Also, although it has hitherto been suggested to initiate the swinging at an early state to hit the inside pitch, to hit the ball close to the pitcher and to delay the start of swinging so that the outside pitch can be hit, it is quite difficult since the timing of start of the batting is not the same. However, if the bat of the structure according to the present invention, the action “to swing the bat as if hitting the grip” can be accomplished and, therefore, the swinging can be simply accomplished with the impact point aligned in a line regardless of the tight, middle and inside balls (FIG. 13C).

The grip portion of the bat referred to hereinabove is such that the shape thereof varies from oval to circular from the grip end towards the grip center, and, although in the case of the oval shape the inclined portion is formed in the upper peripheral edge, if from the upper peripheral edge down to the lower portion of the grip end the side surface is flat with no step formed therein, the little finger side of the bottom hand is apt to slip since the end is nor raised up. In view of this, in the practice of the second preferred embodiment of the present invention, it is recommended to employ any one of the various grip structures shown and described in connection with the previously described first embodiment of the present invention.

Third Preferred Embodiment

In the present invention, a joint portion J for combining the barrel portion B of a metallic cylindrical body and the grip portion G of FRP is formed by using a bonding part JP made from high-elasticity and high-strength resin (Kepler). FIGS. 15A to 15D show the joining method of the barrel portion B and the grip portion G. Metal body part B is made by blank tube processing, and then is subjected to a spinning process by a certain degree to make a form of bat. Then, it is subjected to a shaving processing wherein the raw pipe is set into a mold and beaten to complete the form of a bat. Thereafter, by the head processing and heat treatment processing, the bat is imparted hardness and stickiness. The, the end of the metal barrel portion B is fitted through an adhesive in the recess of the joint part JP. Then, the grip part GP from the top inserted into the metal barrel part B, wherein an annular ridge formed on the upper end outer periphery of the grip parts GP is engaged into an annular groove formed in the upper end inner periphery of the joining part JP (FIG. 15D), and fixed each other with adhesive. Since the impact when hitting the barrel portion is transmitted to the grip portion G by lightly damped degree via the joining part JP, the hitting shock would be alleviated even when off-center impact. On the other hand, the palm grip with the bottom hand on the grip portion G can be maintained, and the hitting energy can be transferred to the metal body section B through the junction parts JP consisting of a high elasticity and high strength resin (Kepler), most of the energy loss due to twist does not occur. Moreover, the maximum energy transfer point of the bat moves close to the grip side than in the case of wood by the weight balance of the metal body part and the FRP grip portion G. As a result of the center of gravity being closer to the center of percussion, the impact energy is increased. Accordingly, the kinetic energy F in the sweet spot of the bat swing would be increased and the largest angular velocity of the bat would be given by amendment of the bat swing, so that the largest batting efficiency could be achieved due to their synergistic effect.

Fourth Preferred Embodiment

The grip portion of the present invention is preferably made from FRP materials, which may be selected of the group consisting of PAN-based fiber FRP, Pitch-based fiber FRP, Glass fiber based FRP, Aramid fiber based FRP, Silicon carbide fiber based FRP and the like. The grip portion G is necessary to be provided with a lock portion which is inclined toward the end of the grip portion from the center of the grip end in order to perform a palm grip with at least the bottom hand, wherein the grip parts GP having a gradually reducing cylinder diameter from the throat portion is preferable to form the grip portion G in combination with the grip end part EP. FIGS. 16A to 16C show a combination of FRP grip parts GP with the grip end parts E-1, wherein the lower end of the grip parts GP is deflected to one side of the grip end parts E-1 and integrated by filling a foamed resin or the like. FIG. 16A is a cross-sectional view showing a locking portion R for locking the bottom hand in the grip portion G of the first embodiment. FIG. 16B is a side view showing the grip portion G having a lock portion R for locking the bottom hand. FIG. 16C is a plan view of the grip portion G of the second embodiment having the locking part R for locking the bottom hand.

FIGS. 17A to 17Ba combination of the grip parts GP with the grip end part E-1 wherein the lower end of the grip parts GP is inserted into the center of the grip end parts E-1, and integrated by filling a foamed resin or the like. FIG. 17A is a cross-sectional view showing a locking portion R for locking the bottom hand in the grip portion G of the third embodiment. FIG. 17B is a side view showing the grip portion G having the lock portion R. FIG. 17C is a plan view of the grip portion G of the third embodiment having the locking part R.

FIGS. 18A to 18C-3
a two-stage grip portion formed by a combination of a cylindrical grip parts GP of FRP with a semi-cylindrical auxiliary grip parts G-1 and an inclined parts G-2 and also an end parts E, which are constituted integrally by filling a foamed resin or the like wherein the former parts G-1 is gasped by the bottom hand and the little finger to the middle finger of the upper hand, while the latter parts G-2 is used to open the thumb and the forefinger of the upper hand. FIG. 18A is a sectional view showing a configuration of the grip portion G of the fourth embodiment for the palm grip with the bottom hand and the middle finger from the little finger of the upper hand. FIG. 18B is a plain view showing the grip end E of a fourth embodiment of the two-stage grip. FIGS. 18C-1, C-2, and C-3 are side views of the grip ends E showing various tilt angles (20, 25, 30°) with respect to a line perpendicular to the axis of the grip end.

Thus, FRP construction of the grip portion makes it possible to combine a variety of the grip part with a variety of the grip end part, thereby providing the grip portion having various lock functions with ease.

In the drawings, B shows a metal barrel portion and G shows a grip portion, while J shows a Joint portion.

Number	Date	Country	Kind
2014-004678	Sep 2014	JP	national
2014-004679	Sep 2014	JP	national
2014-178533	Sep 2014	JP	national
2014-178534	Sep 2014	JP	national
PCT/JP2015/064279	May 2015	JP	national

COMPOSITE BAT STRUCTURE

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CPC

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Priority Claims (5)

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