The present invention relates to the field of golf. In particular, it relates to a golf clubhead and a face plate for a golf clubhead.

One of the characteristics of a golf clubhead is its coefficient of restitution (COR). The COR is important because it effects the distance that a golf ball will travel when struck by the club, in particular a driver. Usually, a player will want to drive the ball as far as possible, and will want to maximise the ratio of the ball speed to the clubhead speed, this sometimes being referred to as the "smash factor". COR is a measure of the efficiency of the transfer of energy during impact, and is represented by a ratio with a value between 0 and 1. A COR of zero implies that all the energy is lost on impact between the clubhead and the ball. Conversely, a COR of 1 indicates that all the energy is transferred from the club to the ball on impact, with no loss of energy to the outside. Neither of these extreme scenarios is achievable in practice, but in general, the greater the COR of the clubhead, the faster the ball will be propelled for a given impact speed. Hence, it is desirable for a clubhead to have a COR as close to 1 as possible.

Furthermore, a typical golfer owns a set of fourteen clubs for use in a game, usually including a driver. The performance characteristics of the driver are determined by its geometry (e.g. face angle, loft), this being chosen by the player according to his ability and personal preferences. Also, the shaft of the driver is usually tailor-fitted to the player, at considerable expense, according to certain factors including his height, swing speed, and preferred degree of shaft flex (stiffness).

A problem faced by the golfer is that he must commit to the purchase of a driver, having a tailor-fitted shaft and a clubhead with a particular geometry, probably based on very limited experience with that driver. As a result, the player might find that he has not bought the most appropriate driver. Furthermore, as the player's skills develop to the point where he is capabie of playing with a more "advanced" driver having different geometry, he will have to purchase a new driver, including a new tailor- fitted shaft.

The present invention aims to alleviate at least to some extent one or more of the problems of the prior art.

According to an aspect of the present invention there is provided a golf clubhead, comprising a clubhead body, including a face for receiving a face part, and a spacer providing at least one recess between the face and the face part. The spacer may be formed integral with the face. The spacer may be configured to contact a rear face of the face part. The spacer may comprise a spine element which extends over a central part of the face. The spacer may comprise spine extension elements which extend from respective ends of the spine element to edges of the face and define a plurality of recesses between the face and the face part. The spine extension elements may define four recesses between the face and the face part. The spine element may extend through a centre of the face. The spine element may be at least in part curved. The width of the spine element and/or the depth of the spine element may vary along the length of the spine element. The clubhead body may comprise at least one attachment fixing for removably attaching the face part to the clubhead body. The attachment fixing may comprise one of a lip or a recess which is disposed at an edge of the face, for engaging the other of a lip or a recess which is disposed at an edge of the face part. The lip or recess may include a metal-filled elastomer, such as rubber. The attachment fixing may comprise a threaded fixing for receiving a counterpart threaded fixing of the face part. The clubhead body may comprise a recess for receiving a portion of the face part which projects from an edge of the face part. The clubhead may comprise a face part, comprising a face part body, including a front face for striking a golf ball and a rear face, the rea face being disposed adjacent the spacer. One or both of the clubhead body and the face part may comprise a chamber for holding a fluid.

According to a further aspect of the present invention there is provided a face part for a golf clubhead, comprising a face part body for fitting to a golf clubhead, including a front face for striking a golf ball and a rear face, and a spacer providing at least one recess between the face part and a face of a golf clubhead body.

The spacer may be formed integral with the rear face. The spacer may be configured to contact the face of the golf clubhead body. The spacer may comprise a spine element which extends over a central part of the rear face. The spacer may comprise spine extension elements which extend from respective ends of the spine element to edges of the rear face and define a plurality of recesses between the rear face and the face of the golf clubhead body. The spine extension elements may define four recesses between the rear face and the face of the golf clubhead body. The spine element may extend through a centre of the rear face. The spine element may be curved. The width of the spine element and/or the depth of the spine element may vary along the length of the spine element.

The face part may comprise at least one attachment fixing for removably attaching the face part to the golf clubhead body. The attachment fixing may comprise one of a lip or a recess which is disposed at an edge of the face part, for engaging the other of a lip or a recess which is disposed at an edge of the face of the golf clubhead body. The lip or recess may include a metal-filled elastomer, such as rubber. The attachment fixing may comprise a threaded fixing for receiving a counterpart threaded fixing of the face part. The face part may comprise a portion which projects from an edge of the face part and is configured to be received in a recess of the golf clubhead body. The face part body may comprise a chamber for holding a fluid, the chamber disposed between the front and rear faces of the face part body. According to a further aspect of the present invention there is provided a golf equipment kit, comprising a plurality of face parts as described herein above.

According to a further aspect of the present invention there is provided a golf club, comprising a golf ciubhead as described hereinabove.

According to a further aspect of the present invention there is provided a removable face plate for a golf ciubhead, comprising : a body, including a face for striking a golf ball, a chamber for holding a fluid, the chamber disposed rearwardly of the face, and an attachment for attaching and detaching the body to and from the golf ciubhead.

The chamber may be defined in part by the face. The body may include a wall which in part defines the chamber and is disposed rearwardly of the face. The face may be outwardly convex. The wall of the body may be inwardly concave, outwardly convex, or generally flat. The body may include a valve for charging/discharging the chamber with/of the fluid. The chamber may comprise a fluid-tight liner inside the body. The fluid may be a liquid, a gel, or a gas, such as argon. At least one aperture may extend through the chamber. The body may be formed of titanium or titanium alloy. The attachment may comprise a lip of the body, for engaging a lip of the golf ciubhead, and threaded fixings to attach the lips together.

According to a further aspect of the present invention there is provided a golf ciubhead, configured to receive a removable face plate as described hereinabove.

According to a further aspect of the present invention there is provided a golf club, comprising a golf ciubhead as described herein above. The golf club may include the removable face plate as described hereinabove. The golf club may include a plurality of the removable face plates. Each removable face plate may have geometry different from the other removable face plates. Embodiments of the present invention will now be described by way of example, with reference to the accompanying figures in which :

Figure 1 shows a golf club face part fitted to a golf clubhead.

Figure 2 shows the face part of Figure 1. Figure 3 shows the clubhead of Figure 1 with the face part removed.

Figure 4 shows an alternative embodiment of the face part of Figure 2.

Figure 5 shows an alternative embodiment of the clubhead of Figure 3.

Figures 6a and 6b show a golf club including a ciubhead and a removable face plate. Figures 7a to 7d show embodiments of the removable face plate of Figures 6a and 6b.

Referring to Figure 1, a golf club assembly comprises a go!f club face part 1 fitted to a golf clubhead 51.

Referring to Figure 2, the face part 1 comprises a face part body 3 which is of appropriate size and shape for fitting to the clubhead 51. The face part body 3 includes a front face 5, which is configured for striking a go!f bail, and a rear face 7, which is configured for fitting to a face of the clubhead, as described hereinbelow.

In this embodiment, the face part 1 includes an attachment for fitting the face part 1 to the clubhead 51, the attachment comprising a lip 9 which extends from and along an upper region of the face part body 3 and is configured to be received by a clubhead slot, as described herein below.

In this embodiment, the attachment further comprises an extension portion 11 of the face part 1, which projects at about ninety degrees from the face part body 3. The extension portion 11 comprises a hole 13 extending therethrough and is shaped to be received by a clubhead body recess, as described herein below. In this embodiment, the face part body 3 further comprises a pair of locating lugs 15 which are disposed at opposite edges of the rear face 7 and are shaped to abut the ciubhead 51 so as to locate the face part 1 on the ciubhead 51. In this embodiment, the face part 1 is of metallic construction.

Referring to Figure 3, the ciubhead 51 comprises a ciubhead body 53, including a spacer which extends over a main part of a face 57 of the ciubhead body 53. In this embodiment, the spacer extends over a central region of the face 57. In this embodiment, the spacer comprises a spine (or rib) 55 which includes four spine extension elements 55a-d which extend to the outer edges of the face 57 so as to divide the face 57 into four, recessed regions.

In this embodiment, the spine 55 and the spine extension elements 55a-d are curved. In this embodiment, the width of the spine 55 and the spine extension elements 55a-d varies along their length.

In this embodiment, the spine 55 and the spine extension elements 55a-d are of the same depth.

In this embodiment, the depth of the spine 55 and the spine extension elements 55a-d is constant along their length.

In this embodiment, the spine 55 and the spine extension elements 55a-d are formed integral with the face 57 of the ciubhead body 53.

In this embodiment, the ciubhead body 53 comprises an elongate recess, or slot, 59 which is disposed along an upper edge of the face 57 and is configured to receive the above-mentioned lip 9 of the face part 1, so as to locate and retain the upper portion of the face part 1 against the ciubhead face 57. In this embodiment, the slot 59 includes a resilient member 61 for exerting a force on the lip 9 of the face part 1 to ensure a snug fit between the face part 1 and the clubhead 51. In this embodiment, the resilient member 61 is elongate and comprises a metal-filled rubber material. In this embodiment, the clubhead body 53 comprises a clubhead body recess 63, which extends rearwardly from a lower edge of the clubhead face 57 along the underside of the clubhead body 53 and is shaped to receive the above-mentioned extension portion 11 of the face part 1. A threaded hole 65 is provided in the clubhead body recess 63 for receiving a screw (Figure 1) for attaching the face part 1 to the clubhead body 53.

In this embodiment, there is a single threaded hole 65 for a single screw connection between the face part 1 and the clubhead body 53.

In this embodiment, the rear face 7 of the face part body 3 is in contact with the spine 55 and the spine extension elements 55a-d when the face part 1 is attached to the clubhead body 53.

In this embodiment, the clubhead 51 is of plastics construction.

Referring to Figures 4 and 5, there is shown an alternative embodiment of the present invention. In this embodiment, the clubhead 51 and the face part 1 are in most respects the same as described hereinabove, except that the spine 55 and the spine extension elements 55a-d extend over the rear face 7 of the face part 1, rather than over the face 57 of the clubhead body 53.

Turning now to aspects related to the operation of the inventive features, when the player swings the golf club and the front face 5 of the face part 1 strikes a golf ball, the face part 1 will undergo some amount of elastic deformation so as to be deflected inwardly toward the clubhead face 57. The level of deformation will be determined by the portion of the front face 1 which comes into contact with the ball, as follows. If contact with the ball occurs at a portion of the front face 5 which is adjacent one of the above- mentioned recessed regions of the clubhead face 57, the face plate 1 will be free to deflect (to some small degree) into the recess and in so doing will absorb a certain amount of energy, thereby causing the golf ball to travel a comparatively lesser distance. Or, if contact with the ball occurs at a portion of the front face 5 which is adjacent the spine 55 or the spine extension elements 55a-d, the face part 1 will be unable to deflect inwardly due to the presence of the spine 55 behind the face part, and so less energy will be lost, thereby causing the ball to travel a comparatively greater distance.

Thus, provision of the spine 55 (and the spine extension elements 5a-d) and the recesses, between the face part body 3 and the face 57 of the clubhead, stiffens the clubhead 51 in certain regions, advantageously endowing the clubhead 51 with different dynamic characteristics, including a higher or lower coefficient of restitution (COR), depending on the portion of the face part 1 which strikes the golf ball.

Furthermore, the face part 1 can be removed and replaced with another face part 1 of different geometry (e.g. face angle, loft), thereby negating the need for the player to buy a range of different clubs.

In an embodiment, the spine 55 and/or the spine extension elements 55a-d are straight.

In an embodiment, the width of the spine 55 and/or and the spine extension elements 55a-d is constant along their length.

In an embodiment, the spine 55 and the spine extension elements 55a-d are of different depth.

In an embodiment, the depth of the spine 55 and/or the spine extension elements 55a-d varies along their length . In an embodiment, the spine 55 and/or the spine extension elements 55a-d are formed separately from the face 57 of the clubhead body 53 (or the rear face 7 of the face part body 3).

In an embodiment, the rear face of the face part is not in contact with the spine 55 and the spine extension elements 55a-d when the face part; 1 is fitted to the clubhead body 53, such that there is a small gap therebetween. This gap allows a limited amount of deflection of the face part 1 in the region of the spine 55.

Referring now to Figures 6a and 6b, a golf club comprises a clubhead 101 and a shaft 105 connected to the ciubhead 101. The clubhead 101 comprises a clubhead body 103, and a face plate 201 removably fitted to the clubhead body 103. The clubhead body 103 forms a cavity 107 and, in this embodiment, includes a receiving lip 109 for fitment with the face plate 201. In this embodiment, the face plate 201 comprises a face plate body 203, including a front face 205 configured for striking a golf ball, and a wall 207. In this embodiment, the wall 207 extends from the front face 205 to form a chamber 211 for holding a fluid. In this embodiment, the wall 207 includes an attachment lip 209 for fitment to the receiving lip 109 of the clubhead body 103.

In this embodiment, the front face 205 is generally convex. In this embodiment, the wall 207 is generally concave.

In this embodiment, the chamber 211 is sealed and contains gas at atmospheric pressure. In this embodiment, the clubhead 101 and the faceplate 201 are of titanium alloy construction.

Regarding the operation of the invention, the attachment lip 209 is attached to the receiving lip 109 by fixings 111 (e.g . threaded couplings such as bolts or screws), thereby removably connecting the face plate 201 to the golf clubhead 101. The golf club is thus ready for use by a player in a game or practice session.

When the player swings the club and the front face 205 strikes a golf ball, the front face 205 undergoes elastic deformation so as to be deflected inwardly toward the wall 207. The deflection of the front face 205 causes a decrease in volume of the chamber 211 and a subsequent increase of pressure of the air inside the chamber 211. A shock wave propagates through the air in the chamber from the front face 205 toward the wall 207. The wall 207 is sufficiently rigid that it does not experience any deflection when it is hit by the Shockwave. Consequently, the Shockwave bounces off the wall 207 toward the front face 205, which springs back to its original shape, thereby transferring additional energy to the ball to make it travel further.

Referring to Figure 7a, in this embodiment, the wall 207 includes apertures 213 extending therethrough to the cavity 107 of the clubhead body 103. When the front face 205 is deflected upon impact with the golf ball, a proportion of the air in the chamber 211 is able to flow through the apertures 213, thereby lessening the rate of the pressure rise in the chamber 211 to provide a damping effect. In this embodiment, the apertures 213 are holes, or optionally perforations or slots.

Referring to Figure 7b, in this embodiment, the face plate 201 includes a valve 215 in the wall 207 for charging/discharging the chamber 211 with/of gas. The valve 215 may include a safety burst disc (not shown), arranged to prevent overpressure in the chamber 211 by bursting at some predetermined pressure level. In this embodiment, the chamber 211 is filled with gas at a pressure greater than atmospheric pressure. The differential pressure has the effect of stiffening the front face 205 to increase the coefficient of restitution (COR) of the face plate 201. This stiffening of the front face 205 is obtained without adding more material, and therefore mass, to the clubhead 101. When the front face 205 strikes a golf ball, the front face 205 will experience little or no inward deflection because such deflection is resisted by the pressure in the chamber 211. Hence, less energy is lost in the impact, with the desirable result that the golf ball will travel a greater distance, this being achieved without an unwanted increase in the weight of the golf club. Referring to Figure 2c, in this embodiment the wall 207 is generally fiat. Referring to Figure 2d, the wall 207 is generally concave. These variations in the shape of the wall 207 provide larger chamber capacity and, therefore, different dynamic and sound characteristics, because the gas in the chamber will be compressed to a lesser extent for a given amount of inward deflection of the front face 205.

In an embodiment of the present invention, a golf equipment kit comprises a golf club having a shaft 105, which may be tailor-fitted to a player, a ciubhead 101, and a selection of removable face plates 201, as described above. The geometry (face angle, loft) of the front face 205 of each face plate 201 differs from the others. The player may change the face plate 201 as and when he chooses. Thus, he is able to enjoy the benefits of the distinct performance characteristics of the various face plates 201, without incurring the expense of buying a range of complete golf clubs, each with its own tailor-fitted shaft. Advantageously, the player may practice and experiment with different face angles and lofts to develop and improve his skills. Furthermore, if a face plate 201 becomes worn or damaged, it may be easily replaced, this being less expensive than replacing an entire club, including the shaft 105. Hence, the golf equipment kit is both highly versatile and cost-efficient.

In the embodiments described herein, the ciubhead 101 is a driver, but the claimed invention is also suitable for other types of golf club.

In embodiments of the invention, any suitable gas is used in the chamber 21 1 , for example air, nitrogen or argon . In an embodiment of the invention, the chamber is filled with a liquid or a gel instead of a gas.

In an embodiment of the invention, the removable face plate 201 and/or the ciubhead 101 is formed from a material other than titanium alloy, for example steel, carbon fibre composite, or even wood. In an embodiment of the invention, the golf ciubhead body 103 is closed by a wall of the body 103.

In an embodiment of the invention, the golf ciubhead body 103 is solid, i.e. the cavity 107 is omitted. In an embodiment of the invention, other suitable fixings which are apparent to a person skilled in the art are used instead of threaded couplings 111 to hold the removable face plate 201 to the ciubhead body 103.

It will be understood that the present invention has been described in relation to its preferred embodiments and may be modified in many different ways without departing from the scope of the invention as defined by the accompanying claims.