Golf club head and golf club

Abstract

To provide a golf club head that can suppress the toe down and is excellent in flight distance performance.SOLUTION: A head 4 includes a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The crown portion 12 includes a protruding portion 20 on a crown outer surface 12a. The protruding portion 20 does not form any part of an outer contour line CL1 of the head 4 in a front view of the head 4 as viewed from a face side. The protruding portion 20 forms an outer contour line CL6 of the head 4 in a heel projection view in which the head 4 that is placed on a ground plane HP such that a shaft axis line Z is perpendicular to the ground plane HP and a face angle is 0 degrees is viewed from a heel side along the ground plane HP. In this head 4, drag and lifting force at a position 9 can be increased. In this head 4, air resistance at a position 6 can be suppressed.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to golf club heads and golf clubs. [Background technology]

[0002] Known specifications that are advantageous for distance include a larger head, a longer club, a softer shaft to increase flex, etc. Also, by making the shaft lighter without reducing the head weight, a club that is easy to swing and has high resilience can be achieved.

[0003] On the other hand, one of the factors that inhibit the flight distance is the toe-down phenomenon, which is disclosed in Japanese Patent Application Laid-Open Nos. 11-267251 and 10-43332. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-267251 [Patent Document 2] Japanese Patent Application Publication No. 10-43332 Summary of the Invention [Problem to be solved by the invention]

[0005] It was discovered that specifications that are advantageous for distance can increase toe down. With conventional golf clubs, there is a trade-off between suppressing toe down and increasing distance, making it difficult to achieve both.

[0006] One object of the present disclosure is to provide a golf club head that can suppress toe-down and has excellent distance performance. [Means for solving the problem]

[0007] In one embodiment, a golf club head has a face portion that forms a striking face, a crown portion that forms an outer crown surface, a sole portion that forms an outer sole surface, and a hosel portion to which a shaft is attached and that specifies a shaft axis. The crown portion has a protrusion on the outer crown surface. In a front view of the head seen from the face side, the protrusion does not form an outer contour line of the head. In a heel projection view of the head seen from the heel side along the ground plane with the shaft axis perpendicular to the ground plane and a face angle of 0 degrees, the protrusion forms an outer contour line of the head. [Effects of the Invention]

[0008] As one aspect, a golf club head can be provided in which toe-down is suppressed and the golf club head has excellent distance performance. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 shows a golf club according to a first embodiment. [Figure 2] Fig. 2(a) is a front view of the head of the first embodiment seen from the face side, showing the head in a reference state, and Fig. 2(b) is a view of the head of the first embodiment seen from the face side in a heel projection position. [Figure 3] FIG. 3 is a plan view of the head of the first embodiment as viewed from the crown side. [Figure 4] FIG. 4 is a side view of the head of the first embodiment as viewed from the heel side. [Figure 5] Fig. 5 is a view of the head of the first embodiment as seen from the inclined heel side, and is a heel projection view. [Figure 6] FIG. 6 shows a part of the outer contour line of the head of the first embodiment when viewed from the toe side and back side. [Figure 7] FIG. 7 shows a cross-sectional view of the outer surface of the head taken along line AA in FIG. [Figure 8] FIG. 8 shows a cross-sectional view of the outer surface of the head taken along line BB in FIG. [Figure 9] FIG. 9 shows a cross-sectional view of the outer surface of the head taken along line CC in FIG. [Figure 10] FIG. 10 shows a cross-sectional view of the outer surface of the head taken along line DD in FIG. [Figure 11] Fig. 11 is an enlarged view of the part surrounded by the square line Q1 in Fig. 7. In Fig. 11, an imaginary extension line of the crown base surface is added. [Figure 12] Fig. 12 is an enlarged view of the part surrounded by the square line Q2 in Fig. 9. In Fig. 12, an imaginary extension line of the crown base surface is added. [Figure 13] Fig. 13(a) is a silhouette of the heel projection of Fig. 5. Fig. 13(b) shows a part of the outline of this silhouette. Fig. 13(b) is a part of the outer outline of the heel projection of the head of the first embodiment. [Figure 14] FIG. 14 is a plan view of the head of the second embodiment as viewed from the crown side. [Figure 15] FIG. 15 is a plan view of the head of the third embodiment as viewed from the crown side. [Figure 16] FIG. 16 is a plan view of the head of the fourth embodiment as viewed from the crown side. [Figure 17] FIG. 17 is a plan view of the head of the fifth embodiment as viewed from the crown side. [Figure 18] FIG. 18 is a plan view of the head of the sixth embodiment as viewed from the crown side. [Figure 19] Fig. 19(a) shows a part of the outer contour of the head of the seventh embodiment when viewed from the toe and back sides, and Fig. 19(b) shows a part of the outer contour of the head of the eighth embodiment when viewed from the toe and back sides. [Figure 20] Fig. 20(a) is a perspective view of the head of the ninth embodiment, and Fig. 20(b) is a cross-sectional view taken along line bb in Fig. 20(a). In Fig. 20(b), the cross section of the head main body is omitted. [Figure 21]Fig. 21(a) is a perspective view of the head body of the head of the ninth embodiment, and Fig. 21(b) is a cross-sectional view taken along line bb in Fig. 21(a). In Fig. 21(b), the cross section of the head body is omitted. [Figure 22] Fig. 22(a) is a perspective view of the head of the tenth embodiment, Fig. 22(b) is a cross-sectional view taken along line bb in Fig. 22(a), and Fig. 22(c) is a cross-sectional view taken along line cc in Fig. 22(a). In Fig. 22(b) and Fig. 22(c), the cross section of the head main body is omitted. [Figure 23] Fig. 23(a) is a perspective view of the head body of the head of the tenth embodiment, Fig. 23(b) is a cross-sectional view taken along line bb in Fig. 23(a), and Fig. 23(c) is a cross-sectional view taken along line cc in Fig. 23(a). In Fig. 23(b) and Fig. 23(c), the cross section of the head body is omitted. [Figure 24] FIG. 24 shows the movement of a golf club during the downswing. [Figure 25] Figures 25(a) and 25(b) are conceptual diagrams illustrating the forces acting on a head with no protrusion at position 9. Figure 25(c) is a conceptual diagram showing the posture of this head at impact. [Figure 26] Figures 26(a) and 26(b) are conceptual diagrams illustrating the forces acting on a head with a protrusion at position 9. Figure 26(c) is a conceptual diagram showing the posture of this head at impact. [Figure 27] Figure 27(a) shows the average head speed (H / S) values ​​for testers 1 to 9. The left side of the bar graph shows the results for club A (no protrusion), and the right side shows the results for club B (with protrusion). Figure 27(b) shows the average distance between the impact point and the face center for testers 1 to 9. The left side of the bar graph shows the results for club A (no protrusion), and the right side shows the results for club B (with protrusion). [Figure 28]Figure 28(a) shows the average face angle for testers 1 to 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Figure 28(b) shows the average smash factor for testers 1 to 9. The smash factor is calculated by dividing the initial ball speed (B / S) by the head speed (H / S). The left side of the bar graph shows the results for club A, and the right side shows the results for club B. [Figure 29] Figure 29(a) shows the standard deviation of head speed (H / S) for testers 1 to 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Figure 29(b) shows the standard deviation of the distance between the impact point and the face center for testers 1 to 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. [Figure 30] Figure 30 shows the standard deviation of face angles for Testers 1 to 9. The left side of the bar graph shows the results for Club A, and the right side shows the results for Club B. [Figure 31] FIG. 31 is a conceptual diagram for explaining the reference state. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Findings that formed the basis of this disclosure) The toe-down phenomenon occurs when the center of gravity of the head is located away from the shaft axis. During a swing, centrifugal force acts on the center of gravity of the head. As shown in Figure 1, the center of gravity CG of the head is located closer to the toe than the shaft axis Z. Therefore, the centrifugal force causes the shaft to bend so that the toe side of the head drops. Also, as shown in Figure 4, the center of gravity CG of the head is located closer to the back than the shaft axis Z. Therefore, the centrifugal force causes the shaft to bend so that the back side of the head drops. Ultimately, the centrifugal force causes the shaft to bend and twist so that the toe and back sides of the head drop. The shaft bends so that the toe side of the head drops and twists in the direction that opens the face. This is the toe-down phenomenon. The greater the centrifugal force, the greater the toe-down. Furthermore, the farther the center of gravity of the head is from the shaft axis, the greater the toe-down.

[0011] As described above, centrifugal force causes the toe side of the head to drop and the back side of the head to drop. These phenomena can be explained separately as toe down and back down, but in this application, they are collectively referred to as toe down.

[0012] To suppress toe-down, it is possible to shorten the club length. However, in this case, the kinetic energy of the head decreases, and the flight distance decreases. To suppress toe-down, it is possible to lighten the head weight. However, in this case, the kinetic energy of the head also decreases, and the flight distance decreases.

[0013] To suppress toe-down, it is possible to shorten the center of gravity distance and / or shallow the center of gravity depth. However, in this case, the high-repulsion area becomes narrower, and the average flight distance decreases. In addition, the face direction becomes unstable, and the average flight distance also decreases.

[0014] Increasing the bending stiffness of the tip of the shaft is one way to suppress toe-down, but this will result in a lower trajectory and reduced distance.

[0015] To reduce the effect of toe-down, it is possible to make the lie angle upright or to make the face hooked. However, a golf club with an upright and hooked face is difficult to address.

[0016] The Corfu club, which is easy to swing, increases head speed. However, the increased head speed increases the centrifugal force acting on the center of gravity of the head, resulting in a large toe-down.

[0017] In this way, factors that increase distance can increase toe down. Excessive toe down can worsen the impact point or the impact angle of the head. Furthermore, excessive toe down can easily cause inconsistencies in the amount of toe down, making the impact point or the impact angle of the head unstable. Therefore, toe down can easily cause energy loss at impact.

[0018] Thus, it has been found that even if a golf club has elements that increase the distance it can travel, if the toe down is large, the distance is reduced. The inventor has discovered that by suppressing the toe down using a means different from conventional methods, it is possible to achieve both suppression of toe down and improved distance performance.

[0019] Hereinafter, the present disclosure will be described in detail based on preferred embodiments, with appropriate reference to the drawings.

[0020] In the present application, a reference state, a reference vertical plane, a toe-heel direction, a face-back direction, a vertical direction, a face center, a heel projection posture, a tilted toe-heel direction, and a heel projection are defined.

[0021] The state in which the head is placed on the ground plane HP at a predetermined lie angle is defined as the reference state. As shown in Figure 31, in this reference state, the shaft axis Z is included in a plane VP perpendicular to the ground plane HP. The shaft axis Z is the center line of the shaft. The plane VP is defined as the reference vertical plane. The predetermined lie angle is listed, for example, in a product catalog.

[0022] In this reference state, the face angle is set to 0 degrees. That is, in a plan view seen from above, the tangent to the face center of the hitting face is set to be parallel to the toe-heel direction. The definitions of the face center and the toe-heel direction will be described later.

[0023] In the present application, the toe-heel direction is the direction of the intersection line NL between the reference vertical plane VP and the ground plane HP (see FIG. 31).

[0024] In this application, the face-back direction is a direction perpendicular to the toe-heel direction and parallel to the ground plane HP. The face side in the face-back direction is also simply referred to as the "face side." The back side in the face-back direction is also simply referred to as the "back side."

[0025] In the present application, the vertical direction is a direction perpendicular to the toe-heel direction and perpendicular to the face-back direction. In other words, in the present application, the vertical direction is a direction perpendicular to the ground plane HP.

[0026] In the present application, the face center is determined as follows: First, an arbitrary point Pr is selected that is approximately near the center of the hitting face in the up-down direction and the toe-heel direction. Next, a plane is determined that passes through this point Pr, extends along the normal to the hitting face at point Pr, and is parallel to the toe-heel direction. A line of intersection between this plane and the hitting face is drawn, and its midpoint Px is determined. Next, a plane is determined that passes through this midpoint Px, extends along the normal to the hitting face at point Px, and is parallel to the up-down direction. A line of intersection between this plane and the hitting face is drawn, and its midpoint Py is determined. Next, a plane is determined that passes through this midpoint Py, extends along the normal to the hitting face at point Py, and is parallel to the toe-heel direction. A line of intersection between this plane and the hitting face is drawn, and its midpoint Px is newly determined. Next, a plane is determined that passes through this new midpoint Px, extends along the normal to the hitting face at point Px, and is parallel to the up-down direction. A line of intersection between this plane and the striking face is drawn, and its midpoint Py is newly determined. This process is repeated to sequentially determine Px and Py. During this process, the new position Py (last position Py) when the distance between the new midpoint Py and the previous midpoint Py is first 0.5 mm or less is the face center.

[0027] The heel projection position is a state in which the shaft axis Z is perpendicular to the ground plane HP and the face angle is 0 degrees. This heel projection position is shown in Figures 2(b) and 5. In the heel projection position, the heel side of the sole is far away from the ground plane HP, and the toe side or the side portion (skirt portion) of the sole is in contact with the ground plane HP. The heel projection position is achieved by rotating the head from the reference state until the shaft axis Z is perpendicular to the ground plane HP. This rotation causes the toe-heel direction of the head to tilt with respect to the ground plane HP (see Figure 2(a)). However, in a planar view seen from above, this rotation does not change the toe-heel direction. In other words, the face angle remains 0 degrees in the heel projection position.

[0028] A vector along the toe-heel direction of the head in the heel projection posture can be decomposed into a vector V1 parallel to the ground plane HP and a vector V2 perpendicular to the ground plane HP (see FIG. 2(b)). The direction of vector V1 parallel to the ground plane HP is defined as the inclined toe-heel direction. The inclined toe-heel direction is perpendicular to the shaft axis Z. The heel side in the inclined toe-heel direction is also referred to as the inclined heel side. The toe side in the inclined toe-heel direction is also referred to as the inclined toe side. In FIG. 2(b), the inclined heel direction is labeled S-heel, and the inclined toe direction is labeled S-toe.

[0029] The heel projection is a projection of the head in the heel projection position viewed from the heel side along the ground plane HP. In other words, the heel projection is a projection of the head in the heel projection position projected toward the heel side along the inclined toe-heel direction. Figure 5 is a heel projection.

[0030] FIG. 1 is an overall view of a golf club 2 including a head 4 according to an embodiment of the present disclosure. FIG. 2(a) is a front view of the head 4. FIG. 2(a) is a view of the head 4 in the reference state as viewed from the face side. FIG. 2(b) is a view of the head 4 in the heel projection position as viewed from the face side. FIG. 3 is a plan view of the head 4 as viewed from the crown side. FIG. 4 is a side view of the head 4 as viewed from the heel side. FIG. 5 is a view of the head 4 as viewed from the tilted heel side. FIG. 5 is a heel projection view of the head 4.

[0031] 1, the golf club 2 includes a golf club head 4, a shaft 6, and a grip 8. The shaft 6 has a tip end Tp and a butt end Bt. The head 4 is attached to the tip end of the shaft 6. The grip 8 is attached to the butt end of the shaft 6.

[0032] The golf club 2 is a driver (number 1 wood). Typically, the club length of a driver is 43 inches or more. Preferably, the golf club 2 is a wood-type golf club.

[0033] The shaft 6 is a tubular body. The shaft 6 has a hollow structure. The material of the shaft 6 is carbon fiber reinforced resin. From the viewpoint of weight reduction, carbon fiber reinforced resin is preferred as the material of the shaft 6. The shaft 6 is a so-called carbon shaft. Preferably, the shaft 6 is formed by curing a prepreg sheet. In this prepreg sheet, the fibers are oriented substantially in one direction. A prepreg in which the fibers are oriented substantially in one direction in this manner is also called a UD prepreg. "UD" stands for unidirectional. A prepreg other than a UD prepreg may also be used. For example, the fibers contained in the prepreg sheet may be woven. The shaft 6 may include metal wire. The material of the shaft 6 is not limited and may be, for example, metal.

[0034] The grip 8 is the part that is held by the golfer during a swing. Rubber compositions and resin compositions are examples of materials for the grip 8. The rubber composition of the grip 8 may contain air bubbles.

[0035] Although not shown, the head 4 has a hollow structure. In this embodiment, the head 4 is a wood type. The head 4 may also be a hybrid type (utility type). The head 4 may also be an iron type. The head 4 may also be a putter type. Preferred materials for the head 4 include metal and fiber-reinforced plastic. Examples of the metal include titanium alloy, pure titanium, stainless steel, maraging steel, and mild steel. Examples of the fiber-reinforced plastic include carbon fiber-reinforced plastic. The head 4 may also be a composite head having a metal portion and a fiber-reinforced plastic portion.

[0036] As shown in Figures 2 to 5, the head 4 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a hitting face 10a. The hitting face 10a is the outer surface of the face portion 10. The hitting face 10a is also simply referred to as the face. The crown portion 12 forms a crown outer surface 12a. The sole portion 14 forms a sole outer surface 14a. The hosel portion 16 has a shaft hole 16a.

[0037] 1 and 4, the head 4 has a center of gravity CG. In this embodiment, the center of gravity CG of the head is located inside the head 4 (hollow portion).

[0038] In FIG. 1, the double-headed arrow B indicates the center of gravity distance of the head 4. The center of gravity distance B is the distance between the shaft axis Z and the center of gravity CG of the head. The center of gravity distance B is not an actual three-dimensional distance, but is the distance when the head 4 is viewed from the front. With the head in the reference state, the shaft axis Z and the center of gravity CG of the head are projected onto the reference vertical plane VP. The center of gravity distance B is the distance in this projected image.

[0039] 4, the double-headed arrow C indicates the depth of the center of gravity of the head 4. The depth of the center of gravity C is the distance between the shaft axis Z and the center of gravity CG of the head. The depth of the center of gravity C is measured along the face-back direction.

[0040] The striking face 10a has a face center Fc defined above.

[0041] The center of gravity CG of the head 4 is not on the shaft axis Z. The center of gravity CG is away from the shaft axis Z. The head 4 has a center of gravity distance B and a center of gravity depth C. The presence of the center of gravity distance B and the center of gravity depth C causes a toe-down phenomenon.

[0042] The crown portion 12 has a protrusion 20 on the crown outer surface 12a. The protrusion 20 is hollow. The protrusion 20 forms a convex portion on the crown outer surface 12a and a concave portion on the crown inner surface.

[0043] In the front view of the head seen from the face side (FIG. 2(a)), the protrusion 20 is not visible. In the front view of the head seen from the face side (FIG. 2(a)), the protrusion 20 does not form the outer contour line CL1 of the head 4.

[0044] In this embodiment, the entire protrusion 20 is provided on the crown outer surface 12a. As shown in Fig. 3, the head 4 has an outer contour line CL2 in a plan view of the head 4. As shown in Fig. 3, the protrusion 20 does not reach the outer contour line CL2. The protrusion 20 does not extend to any part other than the crown outer surface 12a.

[0045] The plan view of the head 4 is a projection image of the head in the reference state projected onto a plane parallel to the ground plane HP. This plan view (FIG. 3) is also called a plan view.

[0046] In the plan view of the head 4 (FIG. 3), the protrusion 20 may reach the outer contour line CL2. In other words, the protrusion 20 may form the outer contour line CL2. The protrusion 20 may extend to a portion other than the crown outer surface 12a. For example, the protrusion 20 may extend from the crown outer surface 12a to the sole outer surface 14a. For example, the protrusion 20 may extend from the crown outer surface 12a to the outer surface of the side portion (skirt portion).

[0047] In a side view (FIG. 4) of the head 4 in the standard state viewed from the heel side in the toe-heel direction, the entire protrusion 20 is visible. This side view has an outer contour line CL3 of the crown outer surface 12a. In this side view, the protrusion 20 does not reach the outer contour line CL3. The entire protrusion 20 is located on the heel side of the face center Fc. A portion of the protrusion 20 may reach as far as the toe side of the face center Fc.

[0048] The crown outer surface 12a has a crown base surface 12b. The portion of the crown outer surface 12a without the protrusion 20 is made up of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface. This convex curved surface is a curved surface that is convex toward the outside of the head 4. As shown in FIG. 3, the crown base surface 12b includes the centroid CR of the plan view of the head 4. The centroid CR is the centroid of the figure formed by the outer contour line CL2.

[0049] FIG. 6 shows a portion of the outer contour line of the head 4 when viewed from the toe side. FIG. 7 shows the cross-sectional line of the outer surface of the head 4 in a cross-sectional view taken along line AA in FIG. 3. FIG. 8 shows the cross-sectional line of the outer surface of the head 4 in a cross-sectional view taken along line BB in FIG. 3. FIG. 9 shows the cross-sectional line of the outer surface of the head 4 in a cross-sectional view taken along line CC in FIG. 3. FIG. 10 shows the cross-sectional line of the outer surface of the head 4 in a cross-sectional view taken along line DD in FIG. 3. FIGS. 7 to 10 include the cross-sectional line of the crown outer surface 12a.

[0050] The protrusion 20 has a contour line CL20, an upper surface 22, and a side wall surface 24. The contour line CL20 is a boundary line between the crown base surface 12b and the protrusion 20. In the plan view of the head 4 (FIG. 3), the contour line CL20 of the protrusion 20 is substantially quadrangular (substantially trapezoidal). In the present application, the term "substantially" includes a configuration in which the sides are curved (not straight) and a configuration in which the corners are rounded. In the contour line CL20 in the plan view of the head (FIG. 3), the radius of curvature of the sides is preferably 25 mm or more, more preferably 40 mm or more, and more preferably 50 mm or more. In the contour line CL20 in the plan view of the head (FIG. 3), the radius of curvature of the rounded corners is preferably 10 mm or less, more preferably 7 mm or less, and more preferably 5 mm or less. The contour line CL20 forms a substantially quadrangular shape.

[0051] The top surface 22 and the side wall surface 24 may be defined by a ridgeline. In a cross-sectional line of the outer surface of the protrusion 20, this ridgeline may be identified as a point or a bend apex having a radius of curvature of 5 mm or less. The radius of curvature of this cross-sectional line may vary depending on the direction of the cross-section, but in determining the radius of curvature to define the ridgeline, a cross-section that minimizes the radius of curvature is selected.

[0052] In a plan view (plan view) of the head 4, the protrusion 20 may be a substantially polygonal shape. When this substantially polygonal shape is a substantially N-sided shape, N may be an integer equal to or greater than 3. N may also be an integer equal to or greater than 3 and equal to or less than 20.

[0053] The contour line CL20 has a first side CL21, a second side CL22, a third side CL23, and a fourth side CL24. The first side CL21 constitutes the side on the toe side and face side of the protrusion 20. The first side CL21 extends toward the back side as it approaches the toe side. The first side CL21 connects the second side CL22 and the fourth side CL24.

[0054] The second side CL22 constitutes the heel-side and face-side side of the protrusion 20. The second side CL22 extends toward the back side as it approaches the heel side. The second side CL22 connects the first side CL21 and the third side CL23.

[0055] The third side CL23 constitutes the heel-side and back-side side of the protrusion 20. The third side CL23 extends toward the toe side and then toward the back side. The third side CL23 connects the second side CL22 and the fourth side CL24. The third side CL23 is a curved line that convexly extends toward the outside of the head 4.

[0056] The fourth side CL24 constitutes the toe-side and back-side side of the protrusion 20. The fourth side CL24 extends toward the back side as it approaches the heel side. The fourth side CL24 connects the third side CL23 and the first side CL21.

[0057] The second side CL22, the third side CL23, and the fourth side CL24 each serve as a base point of the side wall surface 24. That is, the second side CL22, the third side CL23, and the fourth side CL24 each constitute a boundary line between the side wall surface 24 and the crown base surface 12b. On the other hand, the first side CL21 does not serve as a base point of the side wall surface 24. The first side CL21 constitutes a boundary line between the crown base surface 12b and the top surface 22.

[0058] In the present application, a cross section line along the toe-heel direction is also simply referred to as a transverse section line. FIG. 7 is an example of a transverse section line. A transverse section line of the crown outer surface 12a is also referred to as a crown transverse section line. FIG. 7 includes a crown transverse section line. In the present application, a cross section line along the face-back direction is also simply referred to as a longitudinal section line. FIG. 9 is an example of a longitudinal section line. A longitudinal section line of the crown outer surface 12a is also referred to as a crown longitudinal section line. FIG. 9 includes a crown longitudinal section line.

[0059] The inflection point on the crown cross section line can be a point that constitutes the contour line CL20. In other words, this inflection point can be the starting point of the protrusion 20. The cross section line of the crown base surface 12b is a curve that is convex toward the outside of the head 4. The inflection point is a point where the curve that is convex toward the outside of the head 4 changes into a curve that is convex toward the inside of the head 4.

[0060] The apex of the bend in the crown cross-sectional line can be a point that constitutes the contour line CL20. In other words, this apex can be the starting point of the protrusion 20. The cross-sectional line of the crown base surface 12b is a curve that convexly extends outward from the head 4. A line that connects to this curve and bends upward forms a apex. This apex faces inward from the head 4. This apex can be the starting point of the protrusion 20.

[0061] The inflection point on the crown vertical section line can be a point that constitutes the contour line CL20. In other words, this inflection point can be the starting point of the protrusion 20. The vertical section line of the crown base surface 12b is a curve that is convex toward the outside of the head 4. The inflection point is a point where the curve that is convex toward the outside of the head 4 changes into a curve that is convex toward the inside of the head 4.

[0062] The apex of the bend in the crown longitudinal section line can be a point that constitutes the contour line CL20. In other words, this apex can be the starting point of the protrusion 20. The longitudinal section line of the crown base surface 12b is a curve that convexly extends outward from the head 4. A line that connects to this curve and bends upward forms a apex. This apex faces inward from the head 4. This apex can be the starting point of the protrusion 20.

[0063] Typically, the contour line CL20 can be determined by the inflection point or the apex. In selecting a cross section line for this determination, the crown transverse cross section line may be prioritized over the crown longitudinal cross section line. In this case, the crown transverse cross section line is used to identify the inflection point or the apex. If it is difficult to identify the inflection point or the apex using the crown transverse cross section line, the crown longitudinal cross section line can be used. The contour line of the protrusion 20 that is clearly visible can be considered as the contour line CL20.

[0064] The protrusion 20 is a portion that protrudes beyond the crown base surface 12b. An imaginary extension surface 12c, which is an extension of the crown base surface 12b, can be identified below the protrusion 20. The protrusion 20 is a portion that protrudes beyond the imaginary extension surface 12c. The imaginary extension surface 12c can be considered to be the crown base surface 12b that would be formed in the installation area of ​​the protrusion 20 if the protrusion 20 were not present. The imaginary extension surface 12c is formed continuously with the crown base surface 12b. The imaginary extension surface 12c is a curved surface that is convex toward the outside of the head 4. The imaginary extension surface 12c is smoothly connected to the crown base surface 12b.

[0065] Fig. 11 is an enlarged view of a portion surrounded by a square line Q1 in Fig. 7. Fig. 12 is an enlarged view of a portion surrounded by a square line Q2 in Fig. 9.

[0066] The crown cross section in FIG. 11 has an imaginary extension line 12d drawn thereon, which may constitute an imaginary extension surface 12c. The imaginary extension line 12d is a curved line that is convex toward the outside of the head 4. The imaginary extension line 12d is smoothly connected to the cross section of the crown base surface 12b. The imaginary extension surface 12c may be formed by a collection of imaginary extension lines 12d.

[0067] The imaginary extension line 12d smoothly connects the cross-sectional line on one side of the protrusion 20 with the cross-sectional line on the other side of the protrusion 20. The imaginary extension line 12d can be drawn as a Bezier curve. Known Bezier curves include quadratic Bezier curves and cubic Bezier curves. A quadratic Bezier curve has one control point. A cubic Bezier curve has two control points. Preferably, a cubic Bezier curve is used. The Bezier curves in FIGS. 11 and 12 are cubic Bezier curves.

[0068] 11, the crown cross-section line has a first starting point P1 and a second starting point P2. The first starting point P1 and the second starting point P2 are points on the contour line CL20.

[0069] To define an effective tangent at the first starting point P1, points P11 and P12 are defined on the opposite side of the first starting point P1 from the protrusion 20. Point P11 is 0.5 mm away from the first starting point P1. Point P12 is 0.5 mm away from point P11. These 0.5 mm distances are the distance along the crown cross-section line. Points P11 and P12 are points on the crown cross-section line. A tangent line L1 at point P1 to a circle passing through the three points P1, P11, and P12 is determined. If points P1, P11, and P12 are collinear, this line can be defined as the tangent line L1.

[0070] Similarly, to define the effective tangent at the second starting point P2, points P21 and P22 are set on the opposite side of the second starting point P2 from the protrusion 20. Point P21 is 0.5 mm away from the second starting point P2. Point P22 is 0.5 mm away from point P21. These 0.5 mm distances are the distances along the crown cross-section line. Points P21 and P22 are points on the crown cross-section line. A tangent line L2 at point P2 to a circle passing through the three points P2, P21, and P22 is determined. If points P2, P21, and P22 are on the same line, this line can be taken as the tangent line L2.

[0071] Once the tangent line L1 and the tangent line L2 are determined, the intersection point Px of the tangent line L1 and the tangent line L2 is determined. Furthermore, the midpoint M1 between the point P1 and the point Px is determined, and the midpoint M2 between the point P2 and the point Px is determined.

[0072] A Bezier curve can be drawn with point P1 as the start point, midpoint M1 as the first control point, midpoint M2 as the second control point, and point P2 as the end point. In Figure 11, this Bezier curve is the virtual extension line 12d. Since there are two control points, this Bezier curve is a cubic Bezier curve.

[0073] An imaginary extension line 12d can be defined at any position in the face-back direction. A set of these imaginary extension lines 12d can define an imaginary extension plane 12c.

[0074] A similar Bezier curve can be defined for the crown vertical section line. As shown in Fig. 12, the crown vertical section line has a first starting point P1 and a second starting point P2. The first starting point P1 and the second starting point P2 are points on the contour line CL20.

[0075] To define an effective tangent at the first starting point P1, points P11 and P12 are set on the opposite side of the first starting point P1 from the protrusion 20. Point P11 is 0.5 mm away from the first starting point P1. Point P12 is 0.5 mm away from point P11. These 0.5 mm distances are the distances along the crown longitudinal section line. Points P11 and P12 are points on the crown longitudinal section line. A tangent line L1 at point P1 to a circle passing through the three points P1, P11, and P12 is determined. If points P1, P11, and P12 are on the same line, this line can be taken as the tangent line L1.

[0076] Similarly, to define the effective tangent at the second starting point P2, points P21 and P22 are set on the opposite side of the second starting point P2 from the protrusion 20. Point P21 is 0.5 mm away from the second starting point P2. Point P22 is 0.5 mm away from point P21. These 0.5 mm distances are the distances along the crown longitudinal section line. Points P21 and P22 are points on the crown longitudinal section line. A tangent line L2 at point P2 to a circle passing through the three points P2, P21, and P22 is determined. If points P2, P21, and P22 are on the same line, this line can be taken as the tangent line L2.

[0077] Once the tangent line L1 and the tangent line L2 are determined, the intersection point Px of the tangent line L1 and the tangent line L2 is determined. Furthermore, the midpoint M1 between the point P1 and the point Px is determined, and the midpoint M2 between the point P2 and the point Px is determined.

[0078] A Bezier curve can be drawn with point P1 as the start point, midpoint M1 as the first control point, midpoint M2 as the second control point, and point P2 as the end point. In Figure 12, this Bezier curve is the virtual extension line 12e.

[0079] An imaginary extension line 12e can be defined at any position in the toe-heel direction. A set of these imaginary extension lines 12e can define an imaginary extension plane 12c.

[0080] In some cases, the protrusion reaches the outer peripheral edge (outer contour line CL4) of the crown portion (see FIG. 19(b) described later). In this case, the protrusion formed at the boundary between the protrusion and the crown base surface 12b on the crown transverse section line and / or crown longitudinal section line may have only one starting point. When there is only one starting point, an arc along the radius of curvature of the starting point may be defined as the imaginary extension line 12d. That is, in this case, the imaginary extension line 12d may be defined as a circle passing through three points: the first point, which is the starting point; a second point 0.5 mm away from the first point; and a third point 0.5 mm away from the second point.

[0081] In determining the imaginary extension plane 12c, the crown transverse section line may be used in preference to the crown longitudinal section line. The imaginary extension plane 12c may be determined by a set of imaginary extension lines 12d based on the crown transverse section line. If the imaginary extension plane 12c is unclear from the set of imaginary extension lines 12d, the imaginary extension plane 12c may be determined by a set of imaginary extension lines 12e based on the crown longitudinal section line.

[0082] The height H1 of the protrusion 20 may be defined as the height from the imaginary extension plane 12c. As shown in FIG. 11, a normal LN to the imaginary extension plane 12c at a certain point f1 has an intersection f2 with the outer surface of the protrusion 20. The distance from point f1 to the intersection f2 may be defined as the height H1 of the protrusion 20 at the intersection f2. Note that if the protrusion has a point where it does not intersect with the normal LN to the imaginary extension plane 12c but does intersect with the normal to the crown base surface 12b, the height H1 of that point is defined as the height from the crown base surface 12b. In this case, the length of the normal is also the height H1.

[0083] Figure 13(a) is a silhouette of the heel projection of Figure 5. Figure 13(b) shows a part of the contour line of this silhouette. The contour line of this silhouette is the outer contour line CL6 of the heel projection of the head 4. Figure 13(b) shows a part of the outer contour line CL6 of the heel projection of the head 4.

[0084] In the heel projection of the head 4, the outer contour line CL6 of the outer surface of the crown has a convex portion 30. This convex portion 30 is also referred to as a silhouette convex portion. As described above, the protrusion 20 is visible in the heel projection (FIG. 5). The silhouette convex portion 30 is formed by the protrusion 20. The silhouette area S1 of the heel projection is expanded by the silhouette convex portion 30. In other words, the silhouette area S1 of the heel projection is expanded by the protrusion 20. The silhouette area S1 is the area of ​​the figure formed by the outer contour line CL6 of the heel projection, and is the area of ​​the silhouette shown in FIG. 13(a).

[0085] An inflection point on the outer contour line CL6 of the heel projection can be the starting point of the silhouette convex portion. An apex of the bend on the outer contour line CL6 of the heel projection can be the starting point of the silhouette convex portion. In this embodiment, apexes, rather than an inflection point, are the starting points of the silhouette convex portion 30 on both sides of the silhouette convex portion 30. As shown in FIG. 13(b), in the silhouette convex portion 30 of this embodiment, apexes P31 and P32 of the bend are the starting points of the silhouette convex portion 30.

[0086] A cubic Bezier curve can also be drawn for this silhouette convex portion 30 using the method described above. The Bezier curve is shown by the two-dot chain line in FIG. 13(b). This Bezier curve is a curve that smoothly connects the curves adjacent to both sides of the silhouette convex portion 30. This Bezier curve can be the imaginary contour line 30a of the heel projection when the protrusion 20 is not present. The area surrounded by the line of the silhouette convex portion 30 and the imaginary contour line 30a is the additional area S2 due to the protrusion 20. In this embodiment, the additional area S2 is the area of ​​the hatched portion in FIG. 13(b). The additional area S2 is the increase in the silhouette area S1 due to the protrusion 20.

[0087] In addition, in the heel projection, the protrusion constitutes the outer contour line CL6 of the head, but a silhouette convex portion may not be formed. For example, if the protrusion reaches the outer peripheral edge (outer contour line CL4) of the crown portion and extends along this outer peripheral edge, a silhouette convex portion may not be formed. However, even in such a case, the protrusion is visible in the heel projection and increases the silhouette area S1. That is, in this case, an additional area S2 due to the protrusion exists. For example, the silhouette area S11 of the head from which the protrusion has been removed by replacing the protrusion with the imaginary extension surface 12c can be considered, along with the silhouette area S12 of the head with the protrusion. The area (S12 - S11) can be the additional area S2.

[0088] From the viewpoint of suppressing toe-down and stabilizing, the additional area S2 is 30 mm 2 More than 50mm is preferable. 2 More preferably, 100 mm or more 2 The above is more preferable. In order to reduce the air resistance at position 6, there is a limit to the height and volume of the protrusion. From this point of view, the additional area S2 is 500 mm 2 Less than 400mm is preferable 2 Less than 300mm is preferable 2 The following is more preferred:

[0089] From the viewpoint of suppressing toe-down and stabilizing the vehicle, the ratio (S2 / S1) is preferably equal to or greater than 0.005, more preferably equal to or greater than 0.008, and still more preferably equal to or greater than 0.015. From the viewpoint of reducing air resistance at position 6, there is a limit to the height and volume of the protrusion. From this viewpoint, the ratio (S2 / S1) is preferably equal to or less than 0.10, more preferably equal to or less than 0.08, and still more preferably equal to or less than 0.06. S2 / S1 is the ratio of the additional area S2 to the silhouette area S1.

[0090] Referring to Figure 6, a plane whose intersection line PL with the crown outer surface 12a forms a closed figure is called a crown resection plane. In Figure 6, this crown resection plane CP1 is indicated by a two-dot chain line. Although not shown in the side view of Figure 6, in a plan view, the intersection line PL between the crown outer surface 12a and the crown resection plane CP1 forms a closed figure on the crown resection plane CP1. The intersection line PL is an endless circular line. Because Figure 6 is a side view, the intersection line PL is shown as a dot.

[0091] The crown outer surface 12a is cut off by the crown resection plane CP1. A solid whose outer surface is formed by the cut-off crown outer surface 12a and the crown resection plane CP1 is called a resection solid. The volume of this resection solid is called a resection volume. The length of the intersection line PL is L (mm), and the resection volume is V (mm 3 ) The length L is the length of the intersection line PL itself. In other words, the length L is the path length of the intersection line PL. For example, if the protrusion is a cone, the crown cutting plane CP1 cuts the cone, and the intersection line PL is a circle, the length L is the circumference of the circle. In the embodiment of FIG. 3, the intersection line PL can be an endless annular line of a substantially square. In this case, the length L is the path length of the intersection line PL of this substantially square.

[0092] The ratio (V / L) can be an index showing the degree of protrusion of the crown outer surface 12a. The larger the ratio (V / L), the greater the degree of protrusion. The crown outer surface 12a preferably has a portion where the ratio (V / L) is greater than the threshold value X. In other words, it is preferable that a crown resection plane CP1 can be set on the crown outer surface 12a so that the ratio (V / L) is greater than the threshold value X.

[0093] The portion where the ratio (V / L) is greater than the threshold X can be at least a part of the protrusion 20. Preferably, when the ratio (V / L) is greater than the threshold X, all of the intersection lines PL are the intersection lines between the protrusion 20 and the crown resection plane CP1. In other words, it is preferable that the crown resection plane CP1 can be set for the protrusion 20 so that the ratio (V / L) is greater than the threshold X. The crown resection plane CP1 shown in FIG. 6 is also set at a position where all of the intersection lines PL are the intersection lines between the protrusion 20 and the crown resection plane CP1. When all of the intersection lines PL are the intersection lines between the protrusion 20 and the crown resection plane CP1, the maximum value of the resection volume V is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more of the volume of the protrusion 20. The volume of the protrusion 20 can be the volume of the portion cut out by the imaginary extension plane 12c. When all of the intersection lines PL are intersection lines between the protrusions 20 and the crown resection plane CP1, the crown resection plane CP1 may intersect with the imaginary extension plane 12c.

[0094] From the viewpoint of increasing the degree of protrusion of the protrusion 20 and increasing the additional area S2 of the heel projection, the threshold value X is preferably equal to or greater than 20, more preferably equal to or greater than 30, and even more preferably equal to or greater than 40. Excessive protrusion may cause a sense of discomfort in terms of shape. From this viewpoint, the threshold value X is preferably equal to or less than 500, more preferably equal to or less than 450, and even more preferably equal to or less than 400.

[0095] 14 is a plan view of a head 40 of the second embodiment. The only difference between this head 40 and the above-described head 4 is the shape of the protrusion.

[0096] The head 40 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a hitting face 10a. The hitting face 10a is the outer surface of the face portion 10. The crown portion 12 forms a crown outer surface 12a. The sole portion 14 forms a sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The hitting face 10a has a face center Fc defined as described above. The crown portion 12 has a protrusion 50 on the crown outer surface 12a. The protrusion 50 is hollow. The protrusion 50 forms a convex portion on the crown outer surface 12a and a concave portion on the crown inner surface.

[0097] As with the head 4, the protrusion 50 of the head 40 is not visible in a front view of the head seen from the face side. The entire protrusion 50 is provided on the crown outer surface 12a. The head 40 has an outer contour line CL2 in a plan view (plan view) of the head 40. The protrusion 50 does not reach the outer contour line CL2. The protrusion 50 does not extend to any part other than the crown outer surface 12a. The entire protrusion 50 is located on the heel side of the face center.

[0098] The crown outer surface 12a has a crown base surface 12b. The portion of the crown outer surface 12a without the protrusion 50 is made up of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface. This convex curved surface is a curved surface that is convex toward the outside of the head 40.

[0099] The protrusion 50 has a contour line CL50, an upper surface 52, and a side wall surface 54. The contour line CL50 is a boundary line between the crown base surface 12b and the protrusion 50. In a plan view of the head 40, the protrusion 50 is substantially quadrilateral (substantially trapezoidal). The contour line CL50 forms the substantially quadrilateral. The contour line CL50 has a first side CL51, a second side CL52, a third side CL53, and a fourth side CL54.

[0100] The first side CL51 constitutes the face-side side of the protruding portion 50. The first side CL51 extends toward the back side as it approaches the toe side. The first side CL51 connects the second side CL52 and the fourth side CL54.

[0101] The second side CL52 constitutes the heel-side side of the protrusion 50. The second side CL52 extends toward the toe side and then toward the back side. The second side CL52 connects the first side CL51 and the third side CL53. The second side CL52 is a curved line that convexly extends toward the outside of the head 40.

[0102] The third side CL53 constitutes the back-side side of the protruding portion 50. The third side CL53 extends toward the toe side and then toward the back side. The third side CL53 connects the second side CL52 and the fourth side CL54.

[0103] The fourth side CL54 constitutes the toe-side side of the protruding portion 50. The fourth side CL54 extends toward the back side as it approaches the toe side. The fourth side CL54 connects the third side CL53 and the first side CL51.

[0104] The first side CL51, the second side CL52, and the third side CL53 each serve as a base point of the side wall surface 54. That is, the first side CL51, the second side CL52, and the third side CL53 each form a boundary line between the side wall surface 54 and the crown base surface 12b. On the other hand, the fourth side CL54 does not serve as a base point of the side wall surface 54. The fourth side CL54 forms a boundary line between the crown base surface 12b and the top surface 52.

[0105] 15 is a plan view of a head 60 according to the third embodiment. The only difference between this head 60 and the above-described head 4 is the shape of the protrusion.

[0106] The head 60 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a hitting face 10a. The hitting face 10a is the outer surface of the face portion 10. The crown portion 12 forms a crown outer surface 12a. The sole portion 14 forms a sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The hitting face 10a has a face center Fc defined as described above. The crown portion 12 has a protrusion 70 on the crown outer surface 12a. The protrusion 70 is hollow. The protrusion 70 forms a convex portion on the crown outer surface 12a and a concave portion on the crown inner surface.

[0107] As with the head 4, the protrusion 70 of the head 60 is not visible in a front view of the head seen from the face side. The entire protrusion 70 is provided on the crown outer surface 12a. The head 60 has an outer contour line CL2 in a plan view (plan view) of the head 60. The protrusion 70 does not reach the outer contour line CL2. The entire protrusion 70 is located on the heel side of the face center.

[0108] The crown outer surface 12a has a crown base surface 12b. A portion of the crown outer surface 12a that does not have the protrusion 70 is made up of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface.

[0109] The protrusion 70 has a contour line CL70, an upper surface 72, and a side wall surface 74. The contour line CL70 is a boundary line between the crown base surface 12b and the protrusion 70. In a plan view (plan view) of the head 60, the protrusion 70 is substantially pentagonal. The contour line CL70 forms the substantially pentagon. All sides constituting this substantially pentagon have side wall surfaces 74. Although not visible from the angle in FIG. 15 , the side closest to the outer contour line CL2 also has a side wall surface 74.

[0110] 16 is a plan view of a head 80 according to the fourth embodiment. The only difference between this head 80 and the above-described head 4 is the shape of the protrusion.

[0111] The head 80 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a hitting face 10a. The hitting face 10a is the outer surface of the face portion 10. The crown portion 12 forms a crown outer surface 12a. The sole portion 14 forms a sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The hitting face 10a has a face center Fc defined as described above. The crown portion 12 has a protrusion 90 on the crown outer surface 12a. The protrusion 90 is hollow. The protrusion 90 forms a convex portion on the crown outer surface 12a and a concave portion on the crown inner surface.

[0112] As with the head 4, in the head 80, the protrusion 90 is not visible in a front view of the head seen from the face side. The entire protrusion 90 is provided on the crown outer surface 12a. The head 80 has an outer contour line CL2 in a plan view (plan view) of the head 80. The protrusion 90 does not reach the outer contour line CL2. The entire protrusion 90 is located on the heel side of the face center.

[0113] The crown outer surface 12a has a crown base surface 12b. A portion of the crown outer surface 12a that does not have the protrusion 90 is made up of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface.

[0114] The protrusion 90 has a contour line CL90, an upper surface 92, and a side wall surface 94. The contour line CL90 is the boundary line between the crown base surface 12b and the protrusion 90. In a plan view of the head 80, the protrusion 90 is substantially rectangular. The contour line CL90 forms the substantially rectangular shape. All sides that make up this substantially rectangular shape have side wall surfaces 94. Although not visible from the angle of FIG. 16 , the side closest to the outer contour line CL2 also has a side wall surface 94.

[0115] 17 is a plan view (plan view) of a head 100 of the fifth embodiment. The only difference between this head 100 and the above-described head 4 is the shape of the protrusion.

[0116] The head 100 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a hitting face 10a. The hitting face 10a is the outer surface of the face portion 10. The crown portion 12 forms a crown outer surface 12a. The sole portion 14 forms a sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The hitting face 10a has a face center Fc defined as described above. The crown portion 12 has a protrusion 110 on the crown outer surface 12a. The protrusion 110 is hollow. The protrusion 110 forms a convex portion on the crown outer surface 12a and a concave portion on the crown inner surface.

[0117] As with the head 4, in the head 100, the protrusion 110 is not visible in a front view of the head seen from the face side. The entire protrusion 110 is provided on the crown outer surface 12a. The head 100 has an outer contour line CL2 in a plan view (plan view) of the head 100. The protrusion 110 does not reach the outer contour line CL2. The entire protrusion 110 is located on the heel side of the face center.

[0118] The crown outer surface 12a has a crown base surface 12b. A portion of the crown outer surface 12a that does not have the protrusion 110 is made up of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface.

[0119] The protrusion 110 has a contour line CL110, a ridge line 112 formed by vertices, and side wall surfaces 114. The ridge line 112 is formed by the intersection of the side wall surfaces 114. The protrusion 110 does not have an upper surface. The contour line CL110 is a boundary line between the crown base surface 12b and the protrusion 110. The protrusion 110 is formed by one ridge line 112 and two side wall surfaces 114. The protrusion 110 constitutes a convex rib portion having ridge lines.

[0120] 18 is a plan view of a head 120 of the sixth embodiment. The only difference between this head 120 and the above-described head 4 is the shape of the protrusion.

[0121] The head 120 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a hitting face 10a. The hitting face 10a is the outer surface of the face portion 10. The crown portion 12 forms a crown outer surface 12a. The sole portion 14 forms a sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The hitting face 10a has a face center Fc defined as described above. The crown portion 12 has a protrusion 130 on the crown outer surface 12a. The protrusion 130 is hollow. The protrusion 130 forms a convex portion on the crown outer surface 12a and a concave portion on the crown inner surface.

[0122] As with the head 4, in the head 120, the protrusion 130 is not visible in a front view of the head seen from the face side. The entire protrusion 130 is provided on the crown outer surface 12a. The head 120 has an outer contour line CL2 in a plan view (plan view) of the head 120. The protrusion 130 does not reach the outer contour line CL2. The entire protrusion 130 is located on the heel side of the face center.

[0123] The crown outer surface 12a has a crown base surface 12b. A portion of the crown outer surface 12a that does not have the protrusion 130 is made up of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface.

[0124] The protruding portion 130 is divided into multiple (two) portions. The protruding portion 130 has a first portion 132 and a second portion 134. The first portion 132 and the second portion 134 are separated from each other. A dividing groove 136 is formed between the first portion 132 and the second portion 134. This dividing groove 136 extends in a curved manner.

[0125] FIG. 19(a) shows a portion of the outer contour of the head 140 of the seventh embodiment when viewed from the toe and back sides. The head 140 has a protrusion 150. The protrusion 150 is the same as the protrusion 20 of the first embodiment, except that the side wall surface 24 along the third side CL23 of the contour line CL20 is recessed. In the head 140, a space SP is formed between the highest point 152 of the protrusion 150 and the crown outer surface 12a. The highest point 152 is the point where the height H1 is maximum. The definition of height H1 is as described above. From the viewpoint of increasing the drag at position 9, the space SP is preferably provided on the contour-adjacent wall surface CW (described later).

[0126] 19(b) shows a portion of the outer contour line of the head 154 of the eighth embodiment when viewed from the toe side and back side. The head 154 has a protrusion 156. The protrusion 156 reaches the outer peripheral edge (outer contour line CL4) of the crown portion. In a plan view of the head 154, a portion of the contour line of the protrusion 156 coincides with the outer contour line CL4 of the crown portion.

[0127] Figure 20(a) is a perspective view of a head 160 of the ninth embodiment, and Figure 20(b) is a cross-sectional view taken along line bb in Figure 20(a). Figure 21(a) is a perspective view of a head main body 160h of the head 160, and Figure 21(b) is a cross-sectional view taken along line bb in Figure 21(a). In Figures 20(b) and 21(b), the cross section of the head main body is omitted, and only the cross-sectional line of the outer surface of the head main body is shown.

[0128] The head 160 has a head main body 160h, a protruding portion 170, and a fixing jig 172. The protruding portion 170 is detachable from the head main body 160h. The protruding portion 170 is configured by a protruding member 174 that is a separate member from the head main body. The protruding member 174 is detachably fixed to the head main body 160h by the fixing jig 172.

[0129] The head main body 160h has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a hitting face 10a. The hitting face 10a is the outer surface of the face portion 10. The crown portion 12 forms a crown outer surface 12a. The sole portion 14 forms a sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The hitting face 10a has a face center Fc defined as described above. The crown portion 12 has a protruding portion 170 on the crown outer surface 12a. The protruding portion 170 is composed of a protruding member 174. The protruding member 174 is removably fixed to the crown outer surface 12a.

[0130] As with the head 4, the protrusion 170 of the head 160 is not visible in a front view of the head seen from the face side. The entire protrusion 170 is provided on the crown outer surface 12a. The head 160 has an outer contour line CL2 in a plan view (plan view) of the head 160.

[0131] The crown outer surface 12a has a crown base surface 12b. A portion of the crown outer surface 12a that does not have the protrusion 170 is made up of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface.

[0132] The head main body 160h has a port 162. In this embodiment, the port 162 has a screw hole that forms a female screw. In this embodiment, the fixing jig 172 has a male screw. The fixing jig 172 can be screwed to the port 162. Note that in FIG. 20(b), the projections and recesses of the threaded portions of the port 162 and the fixing jig 172 are not shown.

[0133] The protruding member 174 has a base 174a and a standing wall 174b that rises from the base 174a. The standing wall 174b is formed on the edge of the base 174a. In a plan view, the protruding member 174 is substantially polygonal (substantially quadrangular). In a plan view, the protruding member 174 has multiple (four) sides. Of these, the standing wall 174b is provided on one of the sides. The base 174a has a through hole 174c through which the fixing jig 172 is inserted.

[0134] In this manner, in this embodiment, the protruding member 174 is screwed to the fixing jig 172. The fixing structure of the protruding member 174 is not limited to screwing.

[0135] This structure with the standing wall portion 174b can increase the additional area S2 while suppressing air resistance at position 6. The standing wall portion 174b is provided only on the contour-proximate side CS (described later). The standing wall portion 174b forms the contour-proximate wall surface CW (described later). The standing wall portion 174b effectively increases the additional area S2.

[0136] Fig. 22(a) is a perspective view of a head 180 of the tenth embodiment, Fig. 22(b) is a cross-sectional view taken along line bb in Fig. 22(a), and Fig. 22(c) is a cross-sectional view taken along line cc in Fig. 22(a). Fig. 23(a) is a perspective view of a head main body 180h of the head 180, Fig. 23(b) is a cross-sectional view taken along line bb in Fig. 23(a), and Fig. 23(c) is a cross-sectional view taken along line cc in Fig. 23(a). In Figs. 22(b), 22(c), 23(b), and 23(c), the cross section of the head main body is omitted, and only the cross-sectional line of the outer surface of the head main body is shown.

[0137] The head 180 has a head main body 180h, a protruding portion 190, and a fixing jig 192. The fixing jig 192 has a screw member 194 and a screw hole member 196. The protruding portion 190 is detachable from the head main body 180h. The protruding portion 190 is configured by a protruding member 198 that is a separate member from the head main body 180h. The protruding member 198 is detachably fixed to the head main body 180h by the fixing jig 192.

[0138] The head main body 180h has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a hitting face 10a. The hitting face 10a is the outer surface of the face portion 10. The crown portion 12 forms a crown outer surface 12a. The sole portion 14 forms a sole outer surface 14a. The hosel portion 16 has a shaft hole 16a. The crown portion 12 has a protruding portion 190 on the crown outer surface 12a. The protruding portion 190 is composed of a protruding member 198. The protruding member 198 is removably fixed to the crown outer surface 12a.

[0139] As with the head 4, in the head 180, the protrusion 190 is not visible in a front view of the head seen from the face side. The entire protrusion 190 is provided on the crown outer surface 12a.

[0140] The crown outer surface 12a has a crown base surface 12b. A portion of the crown outer surface 12a that does not have the protrusion 190 is made up of the crown base surface 12b. The crown base surface 12b is a smoothly continuous convex curved surface.

[0141] The head main body 180h has a port 182. In this embodiment, the port 182 is a recess. A screw hole member 196 is fixed to this port 182. This fixing can be achieved by, for example, adhesive bonding, welding, or the like. The screw hole member 196 has a screw hole 196a. A screw member 194 is threadedly coupled to the screw hole 196a. Note that in Figures 22(b), 22(c), 23(b), and 23(c), the illustration of the recesses and protrusions of the screw portions of the screw member 194 and the screw hole 196a is omitted.

[0142] The protruding member 198 has a base 198a and a standing wall 198b that rises from the base 198a. The standing wall 198b is formed on the edge of the base 198a. In a plan view, the protruding member 198 is substantially polygonal (substantially quadrangular). In a plan view, the protruding member 198 has a plurality of (four) sides. The standing wall 198b is provided on one of the sides. The base 198a has a through hole 198c through which the screw member 194 is inserted.

[0143] In this manner, in this embodiment as well, the protruding member 198 is screwed to the fixing jig 192. In this embodiment, the screw holes are formed by the screw hole members 196. This embodiment differs from the ninth embodiment in that there is no need to provide screw holes in the head main body 180h.

[0144] The screw hole member 196 may be removably attached to the head main body 180h. For example, the screw hole member 196 may be attached to the head main body 180h by screw connection. In this case, the screw hole member 196 can be replaced. This replacement makes it possible to adjust the weight of the screw hole member 196. For example, the screw hole member 196 can be made relatively light when the protruding member 198 is attached, and can be made relatively heavy when the protruding member 198 is not attached. In this case, the difference in head weight between when the protruding member 198 is attached and when it is not attached can be reduced. It is also possible to make the head weight consistent between when the protruding member 198 is attached and when it is not attached.

[0145] FIG. 24 shows the movement of the golf club 2 during the downswing. The swing starts with a backswing, passes through the top of the swing, and transitions to the downswing, leading to impact. As the downswing progresses, the head speed accelerates. Also, as the downswing progresses, the posture of the head changes.

[0146] At one point during the downswing, the shaft 6 of the golf club 2 becomes parallel to the ground. The position of the golf club 2 at this time is also referred to as position 9. The position of the club at impact is also referred to as position 6. The position between position 9 and position 6 is also referred to as position 7.5. In these designations, the golf club 2 during the swing is likened to the hands of a clock. That is, for example, position 9 corresponds to the 9 o'clock position on a clock (analog clock).

[0147] The posture of the head during the downswing is as follows: A wrist turn occurs during the downswing, and the face returns by the time of impact. Therefore, at impact, the head moves with its face side leading. In other words, at impact, the head moves toward the face side in the face-back direction. Before the wrist turn occurs, the head moves with its heel side leading. Conventionally, before the wrist turn occurs, the head was considered to be moving toward the heel side in the toe-heel direction.

[0148] However, the inventor has found that the direction of movement of the head at position 9 is substantially not the heel side of the toe-heel direction, but the heel side of the inclined toe-heel direction. That is, the inventor has found that at position 9, the head moves with the heel projection (FIG. 5) facing forward. Due to the centrifugal force acting on the head from the top of the swing to position 9, a toe-down motion occurs at position 9. Also, at position 9, wrist cock is released. When wrist cock is released, the club rotates around the grip, and the posture of the head changes in the same way as with toe-down. Due to these factors, the inventor has found that the direction of movement of the head at position 9 is substantially the inclined toe-heel direction.

[0149] By providing the protrusion 20 on the crown portion 12 and increasing the silhouette area of ​​the heel projection, the drag (air resistance force) that the head 4 receives at position 9 increases. This drag cancels out part of the centrifugal force acting on the center of gravity CG of the head. Therefore, the increase in this drag reduces the force that causes toe-down, suppressing toe-down.

[0150] Furthermore, lift can be generated by the protrusion 20 provided on the crown portion 12. At position 9, air flows in an inclined toe-heel direction. This air generates lift on the head 4 according to the same principle as the lift acting on an airplane wing. By providing the protrusion 20, the lift at position 9 is increased.

[0151] The protrusion 20 is not visible in a front view from the face side. The protrusion 20 does not form an outer contour line of the head in a front view of the head seen from the face side. Therefore, the protrusion 20 does not substantially affect the drag (air resistance force) at position 6. The protrusion 20 does not substantially reduce the head speed.

[0152] Figures 25(a) and 25(b) are conceptual diagrams illustrating forces acting on the head 200 at position 9. Figure 25(c) shows the head 200 at impact. The head 200 does not have a protrusion on the crown portion. Figures 26(a) and 26(b) are conceptual diagrams illustrating forces acting on the head 4 at position 9. Figure 26(c) shows the head 4 at impact. The head 4 is the first embodiment described above.

[0153] A centrifugal force acts on the head 200 in position 9. This centrifugal force acts along a line connecting the center of rotation of the golf club 2 and the center of gravity CG of the head. This centrifugal force is broken down into a component F1 parallel to the shaft axis Z and a component F2 perpendicular to the shaft axis Z. Meanwhile, a drag (air resistance force) and a lift force act on the head 200 in position 9. The drag and lift forces act in directions that cancel out the centrifugal force. The resultant force of the drag and lift forces is broken down into a component F3 parallel to the shaft axis Z and a component F4 perpendicular to the shaft axis Z. These forces F1 to F4 are conceptually indicated by arrows. The centrifugal force is greater than the drag and lift forces, resulting in a toe-down motion. As a result, as shown in Figure 25(c), the toe side of the head 200 lowers, the back side of the head 200 lowers, and the striking face 10a opens.

[0154] The provision of the protrusion 20 increases the drag and lift at position 9. The protrusion 20 increases the additional area S2 of the heel projection, thereby increasing the drag. The protrusion 20 also increases the air flow velocity above the head 4 at position 9, thereby increasing the lift. The increased drag and lift increases forces F3 and F4 (see the black arrows in Figures 26(a) and 26(b)). As a result, the force that counteracts the centrifugal force increases, suppressing toe-down. In other words, the head 4 is prevented from sagging toward the toe and back, suppressing the opening of the hitting face 10a (see Figure 26(c)).

[0155] Note that the size of the arrows indicating the forces and their magnitude relationships are not accurate in Figures 25(a), (b) and 26(a), (b). Similarly, the head postures and their relationships are not accurate in Figures 25(c) and 26(c). These figures are intended to provide a qualitative understanding of the effects of this embodiment.

[0156] In each of the above-described embodiments, except for the embodiment in Fig. 17, the protrusion has an upper surface and a side wall surface extending from the upper surface to the outer edge of the protrusion. By providing the side wall surface, the height H1 of the protrusion can be increased, and the additional area S2 can be effectively increased.

[0157] In the head 4 of the first embodiment, the height H1 of the top surface 22 decreases toward the center of the head. The center of the head toward the center of the head may refer to the centroid CR in a plan view of the head 4 (see FIG. 3). In the head in the reference state described above, multiple planes may be set that are perpendicular to the ground plane HP, intersect the top surface 22, and pass through the centroid CR. In cross sections along these planes, the height H1 of the top surface 22 decreases toward the center of the head (toward the centroid CR). This configuration allows the volume of the protrusion 20 to be reduced while increasing the additional area S2. Furthermore, turbulence in the airflow at position 9 is suppressed, allowing the air to flow more easily along the crown outer surface 12a. This airflow contributes to an increase in lift.

[0158] In the head 4 of the first embodiment, the height H1 of the top surface 22 decreases toward the face side. That is, in a cross section along the face-back direction (the above-described crown longitudinal cross section), the height H1 of the top surface 22 decreases toward the face side. This makes it easy to configure the protrusion 20 with a large additional area S2 that is not visible from the face side. Furthermore, the effect on the air flow (flow in the face-back direction) at impact is reduced, and the effect on head speed can also be reduced.

[0159] In the head 80 of the fourth embodiment, the height H1 of the top surface 92 decreases toward the back side. That is, in a cross section along the face-back direction (the above-described crown vertical cross section), the height H1 of the top surface 92 decreases toward the back side. This suppresses the generation of turbulence in the air flow (flow in the face-back direction) at impact, and suppresses a decrease in head speed.

[0160] In the head 140 of the seventh embodiment, a space SP is formed between the highest portion 152 of the protrusion 150 and the crown outer surface 12a. A configuration having this space SP is easy to receive the air flow. This configuration contributes to an increase in drag at position 9.

[0161] In the head 100 of the fifth embodiment, the protrusion 110 has a ridge 112 formed by an apex and a side wall surface 114 extending from the ridge 112 to the outer edge CL110 of the protrusion 110. With this configuration, the volume of the protrusion 110 can be reduced while increasing the additional area S2. With this protrusion 110, the drag at position 9 can be increased while reducing the effect on the air flow at impact (position 6).

[0162] The head 160 of the ninth embodiment includes a head main body 160h that constitutes the crown portion 12, and a protruding member 174 that is detachably fixed to the head main body 160h and that constitutes the protruding portion 170. With this configuration, the protruding portion 170 can be manufactured from a material (such as resin) different from that of the head main body 160h, thereby reducing the weight of the protruding portion 170 and increasing the degree of freedom in molding the protruding portion 170. Furthermore, the performance of the head can be changed by attaching and detaching the protruding member 174. The protruding member 174 is detachably fixed to the head main body 160h by a fixing jig 172. This allows the protruding member 174 to be easily attached and detached. Furthermore, a configuration in which the protruding member 174 can be attached and detached using a dedicated tool facilitates compliance with the rules.

[0163] Increasing the height H1 allows the additional area S2 to be increased. From this viewpoint, the maximum value of the height H1 of the protruding portion is preferably 1 mm or more, more preferably 2 mm or more, and still more preferably 3 mm or more. From the viewpoint of the degree of freedom in designing the position of the center of gravity of the head, the maximum value of the height H1 of the protruding portion is preferably 20 mm or less, more preferably 17 mm or less, and still more preferably 15 mm or less.

[0164] The area of ​​the crown outer surface 12a on the heel side of the face center Fc is Sh (mm 2 ) and the area of ​​the protrusion is St (mm 2) The areas Sh and St are measured in a plan view of the head (e.g., FIG. 3). In FIG. 3, the area Sh is the area of ​​the portion on the heel side of a straight line Lc that passes through the face center Fc and extends in the face-back direction. From the viewpoint of increasing the drag and lift at position 9, the proportion of the area St in the area Sh is preferably 5% or more, more preferably 15% or more, and still more preferably 20% or more. From the viewpoint of the degree of freedom in designing the position of the center of gravity of the head, the proportion of the area St in the area Sh is preferably 70% or less, more preferably 60% or less, and still more preferably 50% or less.

[0165] As described in Fig. 3, the protrusion 20 has a contour line CL20. A distance D1 is defined between each point on the contour line CL20 and the outer contour line CL2. As shown in Fig. 7, this distance D1 is defined as the distance (straight-line distance) on the cross-sectional line.

[0166] The sides that make up the contour CL20 include the side closest to the outer contour CL2. In the embodiment of FIG. 3, the side closest to the outer contour CL2 is the third side CL23. This side is the contour-proximate side CS that is closest to the outer contour CL2 among the multiple sides. In the embodiment of FIG. 14, the second side CL52 is the contour-proximate side CS. The minimum value of distance D1 on the contour-proximate side CS is smaller than the minimum value of distance D1 on the other sides. The maximum value of distance D1 on the contour-proximate side CS is smaller than the maximum value of distance D1 on the other sides. The maximum value of distance D1 on the contour-proximate side CS is smaller than the minimum value of distance D1 on the other sides.

[0167] 3, the contour-nearby side CS is aligned substantially along the outer contour line CL2. The outer contour line CL2 includes the outer contour line CL4 of the crown portion 12 in a plan view of the head. The contour-nearby side CS is aligned substantially along the outer contour line CL4.

[0168] By providing the contour-nearby side CS, the protrusion 20 approaches the outer contour line CL4 on the heel side. This effectively increases the additional area S2 in the heel projection. From this perspective, the maximum value of the distance D1 along the entire contour-nearby side CS is preferably 25 mm or less, more preferably 20 mm or less, and even more preferably 15 mm or less. This maximum value may be 0 mm. When the protrusion 20 reaches the outer contour line CL4 of the crown portion 12, the maximum value of the distance D1 is 0 mm.

[0169] It is preferable that the contour-nearby side CS is along the outer contour line CL4. In this case, the additional area S2 can be effectively increased. From this viewpoint, the maximum value D1max and minimum value D1min of D1 at the contour-nearby side CS are taken into consideration. When the contour-nearby side CS is along the outer contour line CL4, the difference (D1max-D1min) becomes small. From this viewpoint, the difference (D1max-D1min) is preferably 15 mm or less, more preferably 13 mm or less, and still more preferably 10 mm or less. It is more preferable that the difference (D1max-D1min) is 0 mm.

[0170] From the viewpoint of efficiently increasing the additional area S2, the length of the contour-nearby side CS is preferably 20 mm or more, more preferably 30 mm or more, and still more preferably 40 mm or more. From the viewpoint of suppressing excessive extension toward the face side and reducing air resistance at position 6, the length of the contour-nearby side CS is preferably 90 mm or less, more preferably 80 mm or less, and still more preferably 70 mm or less. This length of the contour-nearby side CS is the actual length (path length) of the (three-dimensional) contour-nearby side CS.

[0171] The contour-proximate side CS preferably has a side wall surface. That is, the protrusion preferably has a side wall surface with the contour-proximate side CS as its lower edge. In the embodiment of FIG. 3, the contour-proximate side CS has a side wall surface 24. The side wall surface 24 with the contour-proximate side CS as its lower edge is also referred to as the contour-proximate wall surface. The contour-proximate wall surface CW can efficiently increase the additional area S2 of the heel projection.

[0172] By increasing the height of the contour-proximate wall surface CW, the additional area S2 can be efficiently increased. From this perspective, the height H1 of the upper edge of the contour-proximate wall surface CW is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more. From the perspective of the degree of freedom in designing the center of gravity position of the head, the height H1 of the upper edge of the contour-proximate wall surface CW is preferably 20 mm or less, more preferably 18 mm or less, and even more preferably 15 mm or less.

[0173] From the viewpoint of reducing the air resistance at position 6 while increasing the additional area S2 in the heel projection, the upper edge of the contour-proximate wall surface CW may include the point in the protrusion 20 where the height H1 is maximum.

[0174] In the plan view of FIG. 3, the first side CL21 of the contour line CL20 of the protrusion 20 is the side facing the contour-proximal side CS. The length of this opposing side PS is preferably shorter than the length of the contour-proximal side CS. By shortening the opposing side PS, the impact on the air flow at position 6 can be reduced while increasing the additional area S2. The length of this opposing side PS is the actual length (path length) of the (three-dimensional) opposing side PS. The length of the opposing side PS is preferably 90% or less of the length of the contour-proximal side CS, more preferably 80% or less, and still more preferably 70% or less. The length of the opposing side PS may be 0% of the length of the contour-proximal side CS.

[0175] By lowering the opposing side PS, it is possible to reduce the air resistance at position 6. From this viewpoint, it is preferable that the opposing side PS does not have a side wall surface.

[0176] In the plan view of the head 4 (FIG. 3), the protrusion 20 has a tapered portion whose width W1 decreases as it approaches the opposing side PS from the contour-near wall surface CW. This tapered portion contributes to increasing the additional area S2 while reducing the effect on the air flow at position 6. The width W1 can be measured along the direction of a straight line connecting both ends of the opposing side PS. [Example]

[0177] The effects of the present disclosure will be clarified below by examples, but the present disclosure should not be interpreted as being limited based on the description of these examples.

[0178] [Test 1: Actual Hit Evaluation] A number of testers actually hit the ball with Club A, which had no protrusions, and Club B, which had protrusions, to confirm the effect of the protrusions.

[0179] The testers were nine golfers with a driver head speed of 34 to 39 m / s. A XXIO Eleven driver (shaft flex R, loft angle 10.5°) was used as Club A without a protruding portion. Club B with a protruding portion was a club with a protruding portion molded from a sponge mock-up attached to the crown of the head of Club A. The sponge mock-up was made of a sponge material (EVA foam) and was lightweight. Adjustments were made so that the head weights of Club A and Club B were the same. The position and shape of the protruding portion were the same as those of the head 4 of the first embodiment described above.

[0180] Nine testers hit eight balls with each club. For each hit, head speed, impact point, face angle at impact, and initial ball velocity were measured. From this data, the average head speed, head speed variation (standard deviation σ), average distance between the impact point and face center, variation in distance between the impact point and face center (standard deviation σ), average face angle, variation in face angle (standard deviation σ), and average smash factor were calculated for each tester and each club.

[0181] Figure 27(a) shows the average head speed (H / S) of testers 1 to 9. The left side of the bar graph shows the results for club A (no protrusion), and the right side shows the results for club B (with protrusion). Each arrow indicates whether head speed increased or decreased depending on whether or not there was a protrusion. Head speed was the same with or without a protrusion. It was confirmed that providing a protrusion did not decrease head speed.

[0182] Figure 27(b) shows the average distance between the impact point and the face center for testers 1 to 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Each arrow indicates whether this distance increased or decreased depending on whether the protrusion was present or absent. Of the nine testers, eight experienced a decrease in this distance. It was confirmed that the provision of the protrusion optimized (suppressed) toe down, bringing the impact point closer to the face center.

[0183] Figure 28(a) shows the average face angle for testers 1 to 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Each arrow indicates whether the face angle increased or decreased depending on whether the protrusion was present or absent. A face angle of 0° is most preferable. Of the nine testers, five had face angles approaching 0°, and of these, three had face angles of nearly 0° with club B. It was confirmed that providing the protrusion optimized (suppressed) toe-down and brought the face orientation closer to square.

[0184] Figure 28(b) shows the average smash factor for testers 1 to 9. Smash factor is calculated by dividing the initial ball speed (B / S) by the head speed (H / S). The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Each arrow indicates whether the smash factor increased or decreased depending on whether the protrusion was present or absent. Of the nine testers, eight experienced an increase in smash factor. It was confirmed that the provision of the protrusion optimized (suppressed) toe down, improving the impact point and impact angle, and increasing the smash factor.

[0185] Figure 29(a) shows the standard deviation of head speed (H / S) for testers 1 to 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Each arrow indicates whether the presence or absence of the protrusion increased or decreased the variability in head speed. The variability in head speed was the same with or without the protrusion.

[0186] Figure 29(b) shows the standard deviation of the distance between the impact point and the face center for testers 1 to 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Each arrow indicates whether the presence or absence of the protrusion increased or decreased the variability. Of the nine testers, six experienced a decrease in this variability. It was confirmed that providing the protrusion stabilized the toe down and reduced the variability in the impact point.

[0187] Figure 30 shows the standard deviation of face angles for testers 1 to 9. The left side of the bar graph shows the results for club A, and the right side shows the results for club B. Each arrow indicates whether the presence or absence of the protrusion increased or decreased the variability. Of the nine testers, six experienced a decrease in variability. It was confirmed that providing the protrusion stabilized toe-down and reduced variability in face angles.

[0188] [Test 2: Evaluation using a swing machine] Using the above-mentioned Club A and Club B, toe-down swings were observed using a swing machine. A Computer Controlled Hitting Machine manufactured by Golf Laboratories, Inc. was used as the swing machine, and the test was conducted with the head speed at impact set to 40 m / s. A strain gauge was attached to the shaft to observe the amount of shaft flex at impact. As a result, Club B (with protrusion) showed a 4% (approximately 3 mm) decrease in flex toward the toe-down side at impact compared to Club A (without protrusion). Pressure-sensitive paper was also used to measure the amount of change in the impact point. Compared to Club A, the impact point of Club B shifted toward the heel and sole. The distance of this impact point movement was approximately 6 mm. Thus, the swing machine test confirmed that the protrusions suppress toe-down swings.

[0189] [Test 3: Aerodynamic Simulation] A simulation was performed to confirm changes in drag and lift acting on the head. The simulation was performed using software "STAR-CCM" manufactured by Siemens Digital Industries Software and a polyhedral rear fine mesh. The shape and position of the protrusion were the same as those of the head 4 of the first embodiment, and the maximum protrusion height H1 was 3 mm. The head speed during the downswing was set to 20 m / s at position 9, 30 m / s at position 7.5, and 40 m / s at position 6. As a result, the drag at position 9 increased by 13% in the head traveling direction at position 9 (i.e., the tilted toe-heel direction). Meanwhile, the drag at position 6 (impact) decreased by 2% in the head traveling direction at position 6 (i.e., the face-back direction). Furthermore, the lift at position 9 increased by 28% in the direction perpendicular to the head traveling direction at position 9 (i.e., the tilted toe-heel direction). These increased drag and lift forces counteracted the centrifugal force and reduced the force acting in a direction perpendicular to the shaft axis. Due to the increased drag and lift forces, the force acting in a direction perpendicular to the shaft axis at position 9 decreased by approximately 1%. In this way, it was confirmed that the protrusion increased the drag and lift forces at position 9, suppressing toe-down.

[0190] As these evaluation results show, the superiority of the present disclosure is clear.

[0191] The following notes are provided regarding the above-described embodiments. [Appendix 1] a face portion that forms a hitting face; a crown portion forming an outer surface of the crown; a sole portion forming an outer surface of the sole; a hosel portion to which a shaft is attached and to which a shaft axis is determined; A golf club head having: The crown portion has a protrusion on an outer surface of the crown portion, In a front view of the head seen from the face side, the protruding portion does not constitute an outer contour line of the head, A golf club head in which the shaft axis is perpendicular to the ground plane and the face angle is 0 degrees, and in a heel projection view of the head viewed from the heel side along the ground plane, the protrusion forms the outer contour line of the head. [Appendix 2] 2. The golf club head of claim 1, wherein the protrusion has an upper surface and a sidewall surface extending from the upper surface to an outer edge of the protrusion. [Appendix 3] 3. The golf club head according to claim 2, wherein the height of the upper surface decreases toward the center of the head. [Appendix 4] 3. The golf club head according to claim 2, wherein the height of the upper surface of the protrusion decreases toward the face. [Appendix 5] 3. The golf club head according to claim 2, wherein the height of the upper surface of the protrusion decreases toward the back side. [Appendix 6] 6. The golf club head according to any one of claims 1 to 5, wherein a space is formed between the highest portion of the protrusion and the outer surface of the crown. [Appendix 7] 2. The golf club head of claim 1, wherein the protrusion has a ridge formed by an apex and a sidewall surface extending from the ridge to an outer edge of the protrusion. [Appendix 8] 8. A golf club head according to any one of claims 1 to 7, wherein the head has a head body that constitutes the crown portion and a protrusion member that is detachably fixed to the head body and constitutes the protrusion portion. [Appendix 9] 9. The golf club head according to claim 8, wherein the protruding member is removably fixed to the head body by a fixing jig. [Appendix 10] In a plan view of the head, when an area of ​​the outer surface of the crown on the heel side of the face center is Sh and an area of ​​the protrusion is St, 10. The golf club head according to any one of appendices 1 to 9, wherein the proportion of the area St in the area Sh is 5% or more and 70% or less. [Appendix 11] A golf club head according to any one of claims 1 to 10, a grip, and a shaft, The golf club has the golf club head attached to the tip end of the shaft and the grip attached to the rear end of the shaft. [Explanation of symbols]

[0192] 2. Golf clubs 4, 60, 80, 100, 120, 140, 160, 180... head 6. Shaft 10. Face part 10a···Striking face 12 Crown part 12a: Crown outer surface 12b Crown base 12c Virtual extension surface 12d Virtual extension line 12e···Virtual extension line 14. Sole 16···Hosel part 20, 70, 90, 110, 130, 150, 170, 190...Protrusion 22...Top surface 24... Side wall 174, 198....Protruding member CL1: Outer contour of the head in a front view seen from the face side CL6: Outer contour of heel projection Z: Shaft axis CG: Center of gravity of head

Claims

1. a face portion that forms a hitting face; a crown portion forming an outer surface of the crown; a sole portion forming an outer surface of the sole; a hosel portion to which a shaft is attached and to which a shaft axis is determined; A golf club head having: The crown portion has a protrusion on an outer surface of the crown portion, the golf club head has a head body that constitutes the crown portion, and a protruding member that is detachably fixed to the head body by a fixing jig and that constitutes the protruding portion, In a front view of the golf club head seen from the face side, the protruding portion does not constitute an outer contour line of the golf club head, In a heel projection of the golf club head viewed from the heel side along the ground plane with the shaft axis perpendicular to the ground plane and the face angle at 0 degrees, the protrusion forms the outer contour of the golf club head.

2. The golf club head according to claim 1 , wherein the fixture is fixed to a port provided in the head body.

3. the fixing jig has a screw member and a screw hole member having a screw hole into which the screw member can be threadedly coupled, The golf club head of claim 1 , wherein the threaded hole member is secured to a port provided in the head body.

4. In a plan view of the golf club head, when the area of ​​the outer surface of the crown on the heel side of the face center is Sh and the area of ​​the protrusion is St, 4. The golf club head according to claim 1, wherein the area St occupies 5% to 70% of the area Sh.

5. the contour line of the protrusion has a contour-nearby side that is the side closest to the outer contour line of the golf club head in a plan view, 5. The golf club head according to claim 1, wherein the side wall surface of the protruding portion has a contour-nearby wall surface with the contour-nearby side as a lower edge.

6. a contour line of the protruding portion having a contour-nearby side that is a side closest to an outer contour line of the golf club head in a plan view, and an opposing side that is a side opposing the contour-nearby side, 5. The golf club head according to claim 1, wherein the length of the opposing side is shorter than the length of the contour-neighboring side.

7. a contour line of the protruding portion having a contour-nearby side that is a side closest to an outer contour line of the golf club head in a plan view, and an opposing side that is a side opposing the contour-nearby side, 5. The golf club head according to claim 1, wherein the protrusion has a tapered portion whose width decreases as it approaches the opposing side, and the width is measured along the direction of a straight line connecting both ends of the opposing side.

8. the protrusion increases a silhouette area of ​​the golf club head in the heel projection; 8. The golf club head according to claim 1, wherein when the silhouette area is S1 and an additional area of ​​the area S1 caused by the protrusion is S2, S2 / S1 is 0.005 or more and 0.10 or less.

9. A golf club comprising the golf club head according to any one of claims 1 to 8, a grip, and a shaft, The golf club has the golf club head attached to the tip end of the shaft and the grip attached to the rear end of the shaft.

Images