Abstract: A leakage judgment with respect to a fuel tank is carried out. If the fuel tank is not leaking, a leakage judgment with respect to a canister is carried out. If there is a possibility of leakage in the fuel tank, a leakage judgment with respect to the fuel tank and the canister is carried out. If it is judged that there is leakage in the fuel tank and the canister, the leakage judgment with respect to the canister is carried out.

Abstract: An object of the present invention is to provide a system and method for measurement and analysis of a behavior of a golf club head. Specifically, the system comprises a measurement and analysis device having a marker recognition and positional information acquisition unit for recognizing the at least one marker and acquiring positional information of the recognized at least one marker, a vector calculation unit for calculating a first vector representing a direction of the head and a second vector representing a tangent vector of a trajectory of the head during the golf swing, and a vector angle change acquisition unit for calculating a vector angle between the first vector and the second vector and acquiring a time series change of the calculated vector angle.

Abstract: A golf club head maintains a low weight of a face part, keeps the resilience property of the face part in the rule conformity range, and prevents the resilience performance from decreasing even when a ball is hit by a face part deviating from the sweet spot. The golf club head has a sole, a crown, a toe, and a heel and comprises a face part formed of a metallic material.

Abstract: A golf club head having a hollow internal structure, of which a face portion includes, on its internal surface, an intersection portion located in the central portion of the face portion, a C-shaped outer peripheral portion having an opening on the side of a hosel portion, four main ribs extending from the intersection portion up to an outer edge of the face portion, and an intermediate portion located between the intermediate portion and the outer peripheral portion and the hosel portion. The intermediate portion is divided to four areas by the four main ribs. The thicknesses of a toe side area and a heel side area are greater than the thickness of the outer peripheral portion, and the thicknesses of a crown side area and a sole side area are less than the thickness of the outer peripheral portion.

Abstract: The accuracy or computation speed of mechanical analysis of a golf ball using the finite element method is increased. In the mechanical analysis, a model representing the golf ball is prepared on a computer, and computation is made by the finite element method using elements and nodes. At this time, the elements are made solid elements of hexahedron, the aspect ratio of the shape of each element is set so as to be not lower than 1.0 and not substantially higher than 6.5, and nodes are provided on the sides and at the vertexes of the hexahedron of element.

Abstract: A golf club head with a leading end of a shaft mountable thereon, the golf club head includes: a head main body, formed with a hosel insertion hole; a hosel, formed with a shaft case insertion hole and removably mounted in the hosel insertion hole; and a shaft case, formed with a shaft insertion hole and removably mounted in the shaft case insertion hole.

Abstract: A golf club, includes: a head; a shaft; a shaft case, having a cylindrical shape and fixed to a leading end of the shaft, a hosel, mounted on the head, wherein: the shaft case is inserted into the hosel from an upper end of the hosel; and the shaft case is fixed to the hosel so that an insertion depth of the shaft into the hosel is changed.

Abstract: A golf club is provided which includes: a head having a hosel having a hosel hole; a shaft; a shaft case having a shaft insertion hole to which one end of the shaft is inserted and configured to be inserted to the hosel hole; and a ring-shaped screw member configured to be screwed into one end of the hosel to fix the shaft case in the hosel hole, and to be fitted with an outer face of an one end of the shaft case so as not to contact with the shaft directly, wherein an axis of the shaft insertion hole is nonparallel to an axis of the hosel hole, and an inner face of the hosel hole and an outer face of the shaft case includes a triangular or more polygonal cross-sectional face that is perpendicular to the axis of the hosel hole.

Abstract: A golf club head with a leading end of a shaft mountable thereon, the golf club head includes: a head main body, formed with a hosel insertion hole; a hosel, formed with a shaft case insertion hole and removably mounted in the hosel insertion hole; and a shaft case, formed with a shaft insertion hole and removably mounted in the shaft case insertion hole.

Abstract: A hollow golf club head made of metal includes a face portion, a sole portion, a side portion, and a crown portion. The crown portion and at least a part of the side portion have a Young's modulus lower than the face portion and the sole portion.

Abstract: The accuracy or computation speed of analysis of a club head using the finite element method is improved. In a method of analysis of a golf club head, a model of the golf club head represented by a set of elements including tetrahedral solid elements 30 is prepared on a computer, nodes 32 are provided at the vertexes and on at least one side of the tetrahedral solid element, and the kinetic properties of the golf club head are computed by the finite element method in which the elements and nodes of the model are used and the nodes are made output points of computation. At this time, in at least some of the tetrahedral solid elements, the number of nodes provided per one element is made not fewer than ten.

Abstract: The accuracy or computation speed of analysis of a club head using the finite element method is increased. In a method of analysis of a golf club head, a model of a golf club head represented by the collection of elements including polygonal shell elements 30 each having three or four vertexes is prepared on a computer, six or more nodes 32 are provided at the vertexes and on at least one side of the element, and the kinetic properties of the golf club head are computed by the finite element method in which the elements and nodes of the model are used and the nodes are made output points of computation.

Abstract: This invention provides a golf club head including a face member. The face member includes a face portion forming a face, and a crown extending portion extending backward from the upper edge of the face portion. The width of the crown extending portion in a face to back direction at the toe side is larger than that in the face to back direction at the heel side.

Abstract: A golf club head is provided that includes a face part formed of a metallic material. The face part includes a thick-walled portion centrally located in the face part and configured as an elliptical or circular shape having depressions on two opposite sides thereof, and an outer peripheral portion located on the outer periphery thereof. The thick-walled portion includes a central portion having a first thickness which is greatest in the face part; a first ridge surrounding the central portion and having a second thickness less than the first thickness; and a first valley located between the central portion and the first ridge and having a third thickness less than the second thickness. The outer peripheral portion includes two first areas respectively adjacent to the two depressions of the thick-walled portion and having a fourth thickness less than the third thickness.

Abstract: According to one aspect of the invention, a golf club includes: a head having a hosel having a hosel hole; a shaft; a shaft case having a shaft insertion hole to which one end of the shaft is inserted and configured to be inserted to the hosel hole; and a ring-shaped screw member configured to be screwed into one end of the hosel to fix the shaft case in the hosel hole, and to be fitted with an outer face of an one end of the shaft case so as not to contact with the shaft directly, wherein an axis of the shaft insertion hole is nonparallel to an axis of the hosel hole, and an inner face of the hosel hole and an outer face of the shaft case includes a triangular or more polygonal cross-sectional face that is perpendicular to the axis of the hosel hole.

Abstract: An object of the present invention is to provide a golf club classification method capable of classifying a golf swing precisely. Specifically, the present invention provides a classification method comprising steps of: partitioning the golf swing of the golfer into golf swing trajectories of a back swing, a down swing, and a follow through so as to determine a stable point in the golf swing trajectories as an origin for any two of the trajectories and to assign a two dimensional coordinate to the two golf swing trajectories; determining straight lines connecting each of one point selected within each of the two golf swing trajectories and the origin; calculating angles between each of the determined straight lines and the horizontal line respectively for the two golf swing trajectories; and classifying the golf swing based on a difference between the calculated angles.

Abstract: A golf club head includes a face member having a ball-striking face and an oval thick portion positioned in a central portion of the ball-striking face. The oval thick portion has an oval shape having recesses formed by recessing both sides in a major axis direction in an arc-shaped fashion. The recesses are directed to a toe-side upper portion and a heel-side lower portion. The thickness of the thick portion becomes thickest at a central portion and is gradually reduced from the central portion towards the periphery. The face member is formed such that a portion outside the thick portion is thinner than the thick portion. An occupancy rate of the oval thick portion in the ball-striking face is in a range of 25 to 45%.

Abstract: A method for simulating performance of a golf club head includes dividing a model of the golf club head of a hollow structure using shell elements, and arranging the shell elements on a surface of the model of the golf club head.

Abstract: A golf club includes: a head, formed with a hosel insertion hole, including: a female screw, formed in an inner peripheral surface of the entrance portion of the hosel insertion hole; a hosel, formed with a shaft case insertion hole and mounted on a deep portion of the hosel insertion hole; a shaft case, formed with a shaft insertion hole, a leading end portion of the shaft case being mounted into the shaft case insertion hole; a ring holder, fitted with an outer surface of the shaft case; a screw member, fitted with an outer surface of the ring holder in a peripheral direction of the ring holder; and a male screw, formed on an outer peripheral surface of the screw member so that the screw member is engaged with the female screw; and a shaft, inserted into the shaft insertion hole of the head.

Abstract: A face member of a golf club head includes first and second main ribs disposed inside thereof. The first main rib is extended from a crown side to a sole side and the second main rib is extended from a hosel side to a toe side of the sole. The first and the second main ribs intersect with each other at an intersection portion. Additionally, a first groove is provided from the intersection portion of the rib toward the sole side, and a second groove is provided from the intersection portion of the rib toward the toe side.