Technical Field

The present invention concerns a vibration absorption system to be inserted in the poles used for Nordic walking, hiking and the like, according to the preamble of claim 1 .

Background Art

It has been known in the practice of walking, particularly in the Nordic walking and hiking, that poles are used as posture and walking mode aid elements, as a completion of the movement of the legs, synchronically following their cadence.

In practice, the use of poles entails that the articulations of the upper limbs, in particular wrists and elbows, are subjected to stresses of variable intensity and with high repetition frequency, typically depending on the walking pitch.

In order to overcome this drawback, vibration absorbing devices have been adopted, known as "anti-impact systems", which have the purpose of absorbing vibrations and reducing, as much as possible, the other negative effects on the whole body that occur by the impact of the pole on the ground.

At the present state of art, these devices consist, basically, of an elastic element, arranged inside and coaxially to the pole, at the handle, at the tip or at any other intermediate position.

In practice, these devices, which are springs or rubber bodies (by way of example some are disclosed in documents IT1281623 and EP-A-0904810) have proved to be rather unsatisfactory or even counterproductive in particular conditions of use such as, for example, in the Nordic walking.

A first negative feature is the irregular damping (up to the total absence of the damping); this determines a constant tension of muscles and tendons of the limb in elastic support, which easily leads to the occurrence of tendinitis or other trauma.

A second negative feature is the difficulty of calibrating the elastic element so as to achieve a proper ratio between the millimetric stroke of the tubular body and the elastic constant of the vibration damping element, in order to prevent an excessive rigidity during the step of forced compression and/or early stroke stops in the subsequent step of free expansion, what makes the support somewhat imprecise and not very safe.

A third feature, not less important, is that the devices known up to now, even if small in size, have a weight that affects the whole weight of the pole.

Disclosure

The task of the present invention is to provide a vibration absorption system, commonly known as "damping system", to be applied on poles for walking, in particular for Nordic walking and hiking, which is deprived of the drawbacks of the similar products of known type.

In particular, the task of the invention is to provide a vibration absorption system with a correct damping action (compression/expansion) associated with a simplified and minimum weight shape.

Such scopes are reached by providing a vibration absorption system with the following three features:

- an elastic element that ensures a regular and correct vibration "damping";

- the possibility on including/excluding, by a simple operation, the vibration absorption system, for combining the benefits of a "damping" pole with the benefits of a "rigid" pole and to adjust to the best the equipment according to the type of terrain (dirt or asphalt) and to the type of path (flat or sloping).

- the vibration absorption system comprises as well length locking means of the pole. According to the present invention the vibration absorption system for poles for Nordic walking, hiking and the like comprises an elastic element made of a material which belongs to the family of the polyurethane foams.

The elastic element is predisposed to undergo a compression in the thrust step.

The elastic element is inserted inside a couple of coaxial tubular elements associated in telescopic manner, which made up a rod of the pole.

Advantageously, the elastic element has a cylindrical geometric shape with a ratio between the external diameter and the height comprised between 1 .2 and 1 .8.

Preferably, the elastic element is inserted on a pin associated with a tube steadily connected with a first tubular element of said couple of tubular elements.

Preferably, said elastic element is tightened in use between a base of said tube and a body made up of a shaped spindle shaped at one end of said pin.

Preferably, said pin and said tube are mutually held by a plug, sliding within a longitudinal slit obtained on said tube, to allow the mutual sliding of said tubular elements.

Preferably, said shaped spindle is predisposed to be locked to a second tubular element of said couple of tubular elements.

Preferably, said locked position can be reached by a mutual rotation of at least one of said tubular elements with respect to one another.

Description of Drawings

These and other features of the invention are described in the following in detail, with reference to a specific embodiment, illustrated for indicative and not restrictive purpose along with the attached drawings, wherein:

Figures 1 and 2 (Drawing I) show two partially cross-sectional views of a pole with the vibration absorption system inserted therein in rest and working conditions; Figure 3 (Drawing II) shows an expanded view of the vibration absorption system of Fig. 1 ;

Figures 4-5-6-7 (Drawing III) show respective cross-sectional views of the vibration absorption system of Fig. 1 , in sliding and locking condition on the tubular body;

Figures 8-9-10-1 1 (Drawing IV) show respective cross-sectional views of the vibration absorption system of Fig. 1 , in use (in case of elastic pole) or exclusion (rigid pole);

Figure 12 (Drawing V) shows a partially cross-sectional view of a pole with a vibration absorption system inserted therein with double elastic action, polymeric and mechanic;

Figures 13 - 18 show different shapes of the elastic element;

Figures 19 - 20 (Drawing VI) show two side views of the tube;

Figure 21 shows a cross-sectional view according to the line XXI-XXI of Fig. 19;

Figures 22 - 23 respectively show two views, lifted and cross-sectional, of the tube placed on the tubular element.

Best Mode

As it is shown in Figures 1 - 2, the vibration absorption system, indicated in its entirety with 100, placed between the two coaxial tubular elements which constitute the telescopic rod of the pole that is a tubular element 1 , fixed to the grip, and a tubular element 2, fixed to the part which enters in contact with the ground, is provided with an elastic element 3, coaxially inserted and placed so that, in the thrust step, the cylindrical element 1 slides inside the cylindrical element 2; said elastic element 3 undergoes a compression, and then extends again when the thrust ends, thus performing a damping action which absorbs the vibrations due to the impact of the pole with the ground.

In practice, a good damping, which makes the walking more comfortable, depends on at least three parameters that distinguish the elastic element 3, that is:

- the used material;

- the size;

- the shape taken by the lateral surface of the elastic element when said surface enters in contact with the inner wall of the tubular element 2.

Laboratory and instrumental tests have shown that:

- the most suitable material for the elastic element 3 belongs to the family of polyurethane foams, with a density value comprised between 200 Kg/m ³ and 600 Kg/m ³ ;

- the most suitable material for the elastic element 3 belongs to the family of polyurethane foams, with a hardness value comprised between 20 Shore and 80 Shore;

- the elastic element 3 must have substantially the geometric shape of a cylinder, with cylindrical crown-shaped cross-section, wherein the ratio between the external diameter "D" and the height Ή" (D/H) is comprised between 1 .2 and 1 .8; - the generatrix "K" of the external surface of the cylinder must keep parallel to the longitudinal axis of said cylinder along the whole compression time of the elastic element 3.

From the assembly point of view, as it is shown in Figures 2 and 3, the system is made up of a shaped spindle, indicated in its entirety with 4, having a pin 5 at its top; the pin entering the tube 6; the tube 6 being applied in steady manner, through punching or other methods suitable for such scope, to the end of the tubular element 1 and the tube 6 being the upper support base of the elastic element 3.

The pin 5 and the tube 6 are mutually held through the plug 7, slidable within the longitudinal slit 8 obtained on the tube, to allow the mutual sliding of the tubular elements 1 and 2 and the consequent compression/expansion of the elastic element 3.

The shaped spindle 4 interiorly extends with a body 9 which constitutes the lower support base of the elastic element 3; said body 9 further extends with a conical portion 10, ending with a thread 1 1 , on which a shaped nut 12 is screwed, held by and engaged with the radial tabs 12.1 inside the expander 13, the expander 13 being advantageously made up of two opposite half-shells 13.1 and 13.2 held together by a ring 13.3, in order to allow the insertion of the shaped nut 12.

By such overall constructive solution, in order to allow the compression of the elastic element 3 during the use of the pole, it is necessary to mutually lock the shaped spindle 4 and the external tubular element 2.

As it is shown in Figures 4 - 7, such locking condition can be obtained by the operator through a mutual rotation of at least one of the tubular elements 1 and 2 with respect to the other; this rotation causes the screwing of the nut 12 on the thread 1 1 and, consequently, the forced sliding of the expander 13 upwards, so that the flexible tabs 14 forcedly insert inside the narrowed space 15 defined by the conical portion 10 and by the inner wall of the tubular element 2.

In this way, by the effect of the friction due to the compression of the tabs 14 in a narrowed space, the shaped spindle 4 and the external tubular element 2 remain mutually locked, thus allowing the tubular element 1 to axially slide and compress the elastic element 3 to absorb vibrations.

On the other hand, as it is shown in Figures 8 - 1 1 , it is provided that the longitudinal slit 8 obtained on the tube 6, extends inferiorly by a radial slit 16, where the plug 7 engages, in order to cancel the damping action of the vibration absorption system 100, by making the two tubular elements 1 and 2 mutually constrained in a fixed manner, that is creating the condition of "rigid rod" instead of "telescopic rod".

In practice, starting from the condition in which the tube 6 can longitudinally slide, kept on its path by the plug 7 (Fig. 8 and 10), by performing an angular rotation of at least one of the two tubular elements 1 and 2, also the tube 6 is rotated, so that the plug 7 is consequently placed in the radial slit 15 (Fig. 9 and 1 1 ), thus preventing the above mentioned longitudinal sliding.

[34] Effectively, when the Nordic walking pole, normally for amateur use, for "outdoor walking", is instead used at a competitive level, where the "frequency" of the impact on the ground is higher, the gravitational acceleration discharged on the wrist is remarkable.

[35] To homogenize the damping effect of the elastomer on the pole, also in harder uses of this equipment, the present invention provides to associate the damping action of the polyurethane elastic element 3 with the damping action of an elastic metal element 20, said second element being arranged in coaxial manner and spaced from the above mentioned first element.

[36] From the assembly point of view, as it is shown in Figure 12, the metal elastic element 20, constituted preferably by a helical spring, is placed in the cell defined by the upper end of the pin 5 inserted in the tube 6 and works in accordance with the elastic element 3 in the steps of compression/elastic expansion.

[37] A second solution for homogenizing the damping effect of the elastomer on the pole consists in providing an elastic element 3 with zones of different tensile strength.

[38] A first embodiment of this kind of element provides the use of two layers made of polymers with different tensile strength.

[39] In particular, as it is shown in Figure 13, the elastic element 3.1 is made up of two superimposed rings 3.1 .1 and 3.1 .2; as an alternative, as it is shown in Figure 14, the elastic element 3.2 is made up of two axially concentric rings 3.2.1 and 3.2.2 or, as it is shown in Figure 15, the elastic element 3.3 is made up of two rings 3.3.1 and 3.3.2 inserted inside one into another and wherein one of said elements is provided with a radial collar 3.3.3.

[40] More in general, as it is shown in Figure 16, the elastic element 3.4 is made up of a plurality of superimposed rings made of polymers of different tensile strength and of different thickness.

[41 ] A second embodiment of this kind of elastic element provides to combine, in the same space, a metal elastic element with the polymeric layer.

[42] In particular, as it is shown in Figure 17, the elastic element 3.5 comprises a ring 3.5.1 of polyurethane, with an inserted helical spring 3.5.2; as an alternative, as it is shown in

Figure 18, the elastic element 3.6. is made up of a block 3.6.1 in polyurethane, with an embedded cup-shaped spring 3.6.2.

[43] The invention further provides that, to ensure the "rigid" condition, as it was previously described, the plug 7 is held inside the slit 16 (see Fig 20), through a narrowing 40 obtained in the passage zone between the longitudinal slit 8 and the above mentioned radial slit 16.

[44] In particular, in order to limit the effort that the operator must produce for the rotation of the tubular element 1 or 2 to displace the plug 7 through the narrowing 40 from the slit 8 to the slit 16 and vice versa (working as previously described), the elastic deformation of the above mentioned narrowing 40 is eased by the presence of an underlying bridge 41 that elastically deforms during both the insertion step and the unlocking step of the plug.

[45] Finally, as it is shown in Figures 22 and 23, to hold the tubular element 1 in position on the tube 6, one or more reliefs 50 are provided at the base of the above mentioned tube, in which corresponding openings 51 obtained at the end of the tubular element can be inserted.

[46] The above described invention, which can be applied on poles for pedestrian and sport use as well as on other equipments useful for walking such as crutches and the like, is susceptible of modifications and variants provided they are included within the inventive concept defined by the following claims.