EP0531233B1 - Golf club with device for damping vibrations - Google Patents

Description

The invention relates to a golf club having a vibration damping device.

As is known, a golf club essentially comprises a handle comprising at one end a handle and at the other a striking head.

As is known, when striking the ball, these clubs and more precisely their handle vibrate and the vibrations produced are harmful both for the player and for the accuracy of the ball.

Vibration damping devices have been known for a long time consisting of a high elasticity modulus plate assembled by gluing to the part to be damped by means of a visco-elastic material.

These damping devices are well known and widely used in fields as varied as the suspension of machine tools, engines of all kinds. In document FR-A-2 575 393 of the Applicant, an application of this device to the ski industry has been proposed.

In document US-A-4 660 832, a striking tool has been described such as a tarnish racket or a golf club in which a layer of vibration-absorbing material is placed between the handle and the handle, such as cellular polyurethane.

The invention relates to a golf club comprising a handle and a striking head and a vibration-absorbing assembly, as defined in claim 1.

In other words, the invention consists on the handle of the club not to apply a constraint plate but a tubular, rigid, constraint sleeve, connected to the handle by a visco-elastic material of determined thickness. The stress of the sleeve on the handle then serves as a vibration-absorbing device by absorbing the energy released during striking by transforming it into heat.

In this way, the characteristic visco-elastic intermediate element is blocked between two elements, respectively one deformable: the handle and the other rigid non-deformable: the sleeve. In this way, the characteristic visco-elastic element, which is subjected to shearing, acts as a shock absorber by following the deformations of the handle.

As is known, "viscoelastic materials" are materials which lead to the reduction of the amplitude of the vibrations by degradation of part of the deformation energy in the form of heat. These materials generally have elastic moduli, in particular low YOUNG moduli, but high intrinsic damping coefficients.

• le manchon rigide présente un module d'élasticité E supérieur à 10000 MPa, et une épaisseur comprise entre 0,1 et 3 mm, de préférence au voisinage de 1 mm ; en effet, on a observé que si le module d'élasticité est inférieur à 10000 MPa, le manchon rigide n'agit pas comme une plaque de contrainte et l'amortissement est moins efficace ; de même, si l'épaisseur est inférieure à 0,1 mm, on n'obtient plus aucun effet d'amortissement, alors que si elle excède 3 mm, on augmente inutilement le coût et le poids sans amélioration correspondante ;
• le manchon rigide à haut module d'élasticité est choisi dans le groupe comprenant les alliages d'aluminium, les alliages d'aluminium-chrome-zinc, les matériaux thermodurcissables stratifiés armés de fibres de verre ou de carbone, les matériaux thermoplastiques armés de fibres de verre ou de carbone ;
• le matériau visco-élastique se présente sous la forme d'un manchon coaxial au manche et au manchon rigide, d'épaisseur comprise entre 0,2 et 3 mm, de préférence au voisinage de 0,8 mm ; en effet, on a observé que si la couche de matériau visco-élastique est inférieure à 0,2 mm, on n'obtient plus aucun effet d'amortissement, et que si cette couche excéde 3 mm, on n'obtient aucune amélioration proportionnelle ;
• dans une forme de réalisation avantageuse, le matériau visco-élastique intermédiaire se présente sous forme d'un empilement de couches élémentaires ou d'une juxtaposition de couches dont l'ensemble est revêtu sur ses deux faces, respectivement interne et externe, d'une couche adhésive destinée à reliée ce manchon respectivement à la face externe du manche et à la face interne du manchon rigide ;
• le matériau visco-élastique est choisi dans le groupe comprenant les caoutchoucs butyles, les élastomères de synthèse, seuls, en mélange ou chargés.

It goes without saying that the shock absorber assembly characteristic of the invention must be positioned along the handle at a suitable location corresponding to a vibration belly, or more exactly at the maximum deformation level of this vibration belly, than man of trade determines in a known manner
Advantageously in practice:

• the rigid sleeve has a modulus of elasticity E greater than 10,000 MPa, and a thickness of between 0.1 and 3 mm, preferably in the vicinity of 1 mm; indeed, it has been observed that if the modulus of elasticity is less than 10,000 MPa, the rigid sleeve does not act as a stress plate and the damping is less effective; similarly, if the thickness is less than 0.1 mm, there is no longer any damping effect, whereas if it exceeds 3 mm, the cost and the weight are unnecessarily increased without corresponding improvement;
• the rigid sleeve with high elasticity is chosen from the group comprising aluminum alloys, aluminum-chromium-zinc alloys, thermosetting laminated materials reinforced with glass or carbon fibers, thermoplastic materials reinforced with fibers glass or carbon;
• the visco-elastic material is in the form of a sleeve coaxial with the handle and the rigid sleeve, of thickness between 0.2 and 3 mm, preferably in the vicinity of 0.8 mm; indeed, it has been observed that if the layer of viscoelastic material is less than 0.2 mm, no more damping effect is obtained, and that if this layer exceeds 3 mm, no proportional improvement is obtained ;
• in an advantageous embodiment, the intermediate viscoelastic material is in the form of a stack of elementary layers or of a juxtaposition of layers the whole of which is coated on its two faces, respectively internal and external, with a adhesive layer intended to connect this sleeve respectively to the external face of the handle and to the internal face of the rigid sleeve;
• the visco-elastic material is chosen from the group comprising butyl rubbers, synthetic elastomers, alone, in a mixture or loaded.

In an alternative embodiment, the characteristic shock absorber assembly is slidable along the handle, then is fixable by any appropriate means, such as screwing, clamping, along the latter, preferably at a vibration belly or more exactly at the level of the maximum deformation of a belly of vibrations, determined by groping in a known manner.

In another alternative embodiment, the characteristic shock absorber assembly is positioned in a restricted space provided for this purpose on the handle.

It goes without saying that the handle section can be varied: polygonal, ovoid, circular or other.

The manner in which the invention can be implemented and the advantages which ensue therefrom will emerge more clearly from the following exemplary embodiments in support of the appended figures.

Figure 1 shows a golf club (iron) in summary perspective according to the invention.

Figures 2 and 3 show a detail of this club shown respectively in summary perspective view (Figure 2) and in section (Figure 3) along the plane III-III '.

Figure 4 is another embodiment of the invention shown in longitudinal section.

A golf iron according to the invention comprises a handle (1) for example of metal, terminated at its end by a handle, and connected at its other end to a head designated by the general reference (3), having a face of strike (4). A fitting (5) connects the head (3) to the handle (1).

The shock absorber assembly characteristic of the invention, designated by the general reference (10), comprises a rigid tubular sleeve (11) made of an aluminum-chromium-zinc alloy known under the name ZICRAL (registered trademark of CEGEDUR), having a modulus of elasticity of 12,000 MPa, a thickness of 0.8 mm, a height of 40 mm and an internal diameter of 12 mm.

This damper assembly (10) is positioned on the handle (15) at a location corresponding to a vibration belly determined beforehand by any known means. On a golf handle, this belly is located in the vicinity of the first third of the handle (1) starting from the head (3).

The rigid circular tubular sleeve (11) is connected at (15) to the handle (1) also circular by means of a second sleeve (12) coaxial both with the handle (1) and with the rigid sleeve (11) with high modulus of elasticity and the two faces of which, respectively internal and external, have been previously coated with an adhesive layer, not shown, so as to promote the joining between the rigid constraint sleeve (11) and the handle (1). The intermediate visco-elastic connecting layer (12) has a damping coefficient at 25 ° C tangent δ between 0.4 and 1.2, preferably between 0.6 and 0.8.

By positioning the shock absorber assembly (10) along the handle (1) at the point of maximum deformation of the vibration belly (15), there is a marked improvement in the damping of vibrations.

In a variant not shown, the characteristic damping element (10) can slide temporarily along the handle (1). To do this, the intermediate viscoelastic layer (12) adheres only to the external rigid sleeve (11) but does not adhere to the handle (1) to allow this sliding. The operator determines by trial and error the location of the vibration belly (15) and then positions this damping element by any known means, such as screwing, gluing or clamping.

Figure 4 is another embodiment of the invention in which the handle (1) has a restriction (20) into which will be inserted the damping element (10) whose internal diameter corresponding substantially to the external diameter of the tube. This form of execution has the advantage of keeping a regular section on the handle.

Claims (7)

1. A golf club comprising a shaft (1) having a first end terminated by a grip (2) and another end terminated by a striking head (3,4), said shaft comprising a vibration damping device, characterised:

   - in that said vibration damping device is constituted by a rigid tubular sleeve (11), coaxial with the shaft (1), fixed on the shaft (1) between the striking head (3,4) and the grip (2)

   - and in that the sleeve (11) is connected to the shaft (1) by a visco-elastic material (12) of nought point two to three millimeters (0,2 to 3 mm) thickness, which is constrained by the sleeve (11) on the shaft (1).
2. A golf club as claimed in claim 1, characterised in that the rigid sleeve (11) has an elastic modulus E greater than 10.000 MPa, a thickness between nought point one to three millimeters (0,1 to 3 mm), and is chosen from the group comprising aluminum alloys, aluminum-chromium-zinc alloys, laminated thermosetting material reinforced with glass or carbon fibers, thermoplastic materials reinforced with glass or carbon fibers.
3. A golf club as claimed in claim 1, characterised in that the intermediate viscoelastic material (12) is formed from a superposition of elementary layers coated on its two, respectively inner and outer, faces with an adhesive layer intended to connect it to the shaft (1) and to the rigid sleeve (11).
4. A golf club as claimed in one of claims 1 to 3, characterised in that the viscoelastic material (12) is chosen from the group comprising butyl rubbers, synthetic elastomers, alone, as a mixture or filled.
5. A golf club as claimed in one of claims 1 to 4, characterised in that the vibration damping element (10) can slide temporarily along the shaft and can then be fixed along said shaft at the point of the maximum disturbance of a vibration antinode region.
6. A golf club as claimed in one of claims 1 to 5, characterised in that the vibration damping element is positioned in a restriction (20) made for this purpose on the shaft (1).
7. A golf club as claimed in claim 1, comprising a striking head (3,4) and a shaft (1), characterised in that the vibration damping element (10) is disposed in the vicinity of the first third of the shaft starting from the head (3,4).

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