Shock absorbing device for ski poles, walking sticks, crutches and similar articles

A shock absorbing device for poles for skiing, for excursions, for walking, for crutches and similar articles has two structures (1) and (2) in general cylindrical, coaxial with the longitudinal axis of the structure to be dampened. One of the two structures is partially placed within the other with the possibility of sliding with respect to the same corresponding to the stresses which are applied on the structures during use. Between the two structures there is placed an elastic material capable of dampening the stresses in two directions. The device is characterized by the particular shape of the piece of elastic material.

FIELD OF THE INVENTION
 The present invention relates to a shock absorbing device for rods or poles
 being used for skiing, for excursions, for walking, for crutches and
 similar articles.
 BACKGROUND OF THE PRIOR ART
 It is known that the practice of skiing both when one goes downhill as well
 as at the bottom, requires the use of poles in a variety of situations
 with variable intensity and frequency above all as a function of the
 particular type of activity being carried out. In particular, during
 skiing when one goes downhill the poles are used as assistance elements
 during the phases of the departure and thrust in maintaining the
 equilibrium and in applying the trajectory, and also when one goes uphill.
 On the contrary, in sking at the bottom and also during the practice of
 walking in ski boots, the poles are used to complete the motion of the
 legs following typically the cadence in a synchronous manner. Both these
 situations involve stresses of different nature and intensity which are
 transmitted to the limbs which maneuver the poles. Specifically in sking
 when one goes downhill these stresses are typically short, of great
 intensity and relatively sporadic and irregular. On the contrary, in
 skiing at the bottom, the stresses result more prolonged and of lower
 intensity but with high frequency of repetition typically equal to the
 forward steps. In every case for activities which are carried out with
 substantial intensity and/or extension of the period of time and in a
 particular manner for professional athletes, these stresses are capable of
 favoring or determining pathological conditions of the articulations of
 the upper limbs, in particular the wrists and the elbows. For the purpose
 of obviating these drawbacks there have been already adopted for some time
 shock absorbing devices above all on the poles which are used for the
 practice of skiing on a road (ski roller) and on the poles being used for
 pedestrian excursions. These known devices consist essentially of a simple
 spiral spring which is placed internally and coaxially with the pole.
 These devices may be placed at the level of the handgrips, or the tips,
 but also in any other intermediate position of the pole.
 In actual practice these devices have given unsatisfactory results and in
 some instances have produced the opposite result during use. The absence
 of damping in fact brings about a constant tension of muscles and
 tendonitis of the limbs in elastic bearing and favor the occurrence of
 troubles such, for instance in the tendonitis In addition, these devices
 are capable of increasing the total weight of the pole and also increase
 the final cost for the user. These devices have been partially eliminated
 with a shock absorbing device for poles and similar articles described in
 Italian patent application, No. VI95A000131, dated Aug. 3, 1995, filed in
 the name of the applicant as in the present application. This device
 provides similarly to the devices of known type the presence of two
 cylinders coaxial with the longitudinal axis of the structure to be
 dampened, one of the two cylinders being placed partially within the
 other, with the possibility of sliding with respect to the same in the
 presence of stresses which occur on the structure during use following the
 contact with the bearing surface and is characterized mainly by the fact
 that it utilizes an elastomer as the elastic means.
 Both the device described hereinabove as well as other devices which have
 been proposed for the same purpose operate with a damping action only in
 one direction of motion, generally from the position of rest in the
 direction of compression so that the result is they are substantially
 rigid in the opposite direction. Consequently the return of the rest
 position of the elastic element following the removal of the load causes a
 dry recoil which for instance amounts to a nuisance also because of the
 noise being generated over prolonged use.
 SUMMARY OF THE INVENTION
 An object of the present invention is to provide a shocking absorbing
 device for poles and similar articles which is free of the drawbacks
 described hereinabove and which in particular is effective in a dampening
 action in both the two phases, that is the phase of compression followed
 by the phase of traction. In particular with the device of the present
 invention in addition to achieving a shock absorbing action of the impact
 of the pole with the ground in a manner to generate a feeling of comfort
 in the limb which performs the maneuver the following results are
 possible:
 the axial motion is adequately dampened;
 the relation between both the compression force or positive force and the
 traction force or negative force and the deformation does not result
 linear with substantial initial yielding and a progressive stiffening;
 transmission of the maximal pair required by the internal blocking
 mechanism which has an expansion screw and which is ordinarily adopted in
 the telescopic poles for the purpose of joining reciprocally the parts
 which constitute the pole and/or the pole with the handgrip;
 the device which is contained in the interior of the pole or in one of the
 portions of the pole requires a minimal axial space, has substantially
 reduced weight and allows to assemble rapidly the various components with
 economical results.
 The following results are achieved according to a first embodiment of the
 invention by providing that in the known constructive solution described
 hereinabove, that is the constructive solution composed of two cylinders
 which are coaxial and which slide reciprocally, the intermediate elastic
 element results firmly anchored with its two opposite bases to the
 corresponding surfaces of the bearing of the two above bodies.
 As it is easily understandable with this constructive device the shock
 absorbing action occurs in addition to obviously during the compression
 phase of the elastic element also during the subsequent expansion phase,
 that is the traction phase due to the internal elastic return which the
 same structure being expanded carries out.
 For the purpose of preventing that the return course, that is the expansion
 course turn out to be excessive and causing the yielding of the elastic
 element or the separation from the bearing bases, there is provided the
 action of a structure which carries out a rigid end course which
 intervenes after a certain predetermined traction course. This end course
 structure is advantageously applied to the extremity of a floating shaft,
 the latter being integral with one of the two coaxial cylindrical bodies
 which slide reciprocally one with the other.
 According to another embodiment of the invention for the purpose of
 generating a shock absorbing action both during the compression as well as
 during the traction phase, there is provided the use always in the
 interior of the coaxial cylindrical bodies which slide reciprocally one
 with respect to the other, of two elastic means which operate on the two
 faces of the common bearing face of the cylinder which is placed
 internally.
 With this second constructive solution the shock absorbing action is
 further reinforced by providing that at least one of the two elastic means
 which are placed one opposite to the other has a dimension such that it
 may slide against the containing wall so that during the compression phase
 it operates as a typical friction piston.
 A good shock absorbing device which offers constant elastic elements and
 suitably not linear, in addition to the use of an elastomer is achieved by
 using conical or bi-conical metallic springs.
 The maximal compactedness and light weight of the shock absorbing device is
 achieved by using a single elastic element which operates both during the
 traction and during the compression phase and which is provided with a
 lock for stopping the shaft, the shaft being obtained with an elastomer of
 a foamed polyurethane of the type for instance commercially known under
 the names of CELLESTO or POLYCEL or with metallic springs of the type
 "bovolo" which means a twisting spring with conical helix and rectangular
 section or particular conical springs in lamination which require minimal
 space under equal excursion travels and which due to their particular
 constructive form may be obtained with an inherent damping. The avoidance
 of the reciprocal rotation between the elements which constitute the pole
 and/or between the pole and the handle is achieved advantageously by
 providing that the central shaft offer a non-circular section so it is
 possible to transmit a twisting torque directly from the external cylinder
 to which it is anchored to the internal cylinder within which it slides
 without requiring the use of further guides or extensions such as in the
 known devices which negatively increase the space and this becomes
 particularly significant in telescopic poles in which there are several
 parts constituting the pole.
 Finally there is provided that the end of the course of the floating shaft
 is achieved by means of flexible tongues which engage the extremity of the
 same shaft during its traction course and stop it.
 Constructively the shock absorbing device of the present invention in its
 several forms results to be constituted by a limited number of components,
 none of which requires a complex construction.

As shown in FIGS. 1, 2 and 3, the device of the invention contains
 schematically a first member (1) which in general is cylindrical and is
 disposed externally and by way of example could be made integral with the
 handgrip of the pole, the handgrip being designated (1a) and shown in
 phantom in FIG. 3.
 In the interior of the first member (1) there is inserted partially a
 further element (2) which is also cylindrical and which has the
 possibility of sliding relatively to the first member in an essentially
 axial direction. By way of example, the element (2) may be integral with
 that part of the pole which is intended to be effectively in contact with
 the bearing surface. Between the end plates (1') and (2') of member (1)
 and element (2) which are cylindrical, the end plates being opposite one
 to the other, an elastic member is placed. The latter according to the
 first embodiment of the invention is constituted by a metallic spring (3)
 of the "bovolo" type while according to a second embodiment of the
 invention the elastic member is constituted by elastomer (4). Both elastic
 members (3) and (4) are held in place by means of floating shaft (5) which
 is integral with end plate (1') and which extend through end plate (2').
 A first novel feature of the invention consists of providing that the two
 elastic members (3) and (4) described hereinabove have both bases of rest
 on the bearing surface firmly anchored to the corresponding end plates
 (1') and (2').
 Several manners of anchoring may be used such as mechanical means with
 adhesive glues.
 It is evident that when due to the stresses of the rest surface/the
 cylindrical element (2) is inserted to a greater extent within the
 external cylindrical member (1) a deformation of the elastic member
 results which)due to its elasticity produces the desired shock absorbing
 or damping action during compression. It is also evident that after this
 effect ends, the elastic member expands and and always due to its
 elasticity it produces a absorbing action during the traction.
 In order to suitably regulate the amplitude of the return course of the
 elastic member and to prevent a yielding result, there is provided a
 structure (6) which provides for the end of the course, this structure
 being applied to the end of the floating shaft (5), the latter being
 blocked on the base (2') according to manners which will be described
 hereinbelow.
 An action of dampen both during the compression and during the traction
 stage is also achieved with a solution which provides for the use of two
 elastic member (7 & 8) which are counterposed one to the other and which
 act on the same base 2'. In particular the lower elastic member (8) is
 added to the upper elastic member hub (7), the lower elastic member (8)
 being blocked by means of pan (9) attached to the end of the floating
 shaft (5).
 It is evident as shown in FIG. 3 that during the compression phase there is
 generated an action of damping due to the elastic member (7) which is
 compressed and also an action of damping produced by the elastic member
 (8) which is being lengthened. Analogously during the subsequent phase of
 traction the action of damping results after the elastic member (7) has
 lengthened, the latter being braked by the elastic member (8) which is
 compressed.
 In order to increase the effect of damping in both directions there is
 provided that a portion or the entire lateral surface (10) of one of the
 two elastic members, preferably the lower member (8) comes in contact with
 the surface of the corresponding containing element.
 In both constructive solutions described hereinabove non-linearity is
 obtained between the deformation and the applied load as shown in FIG. 4
 relative to the use of a single elastic member and in FIG. 5 due to the
 use of two elastic members which are placed one against the other.
 Several constructive means (6) for ending the course are shown in FIGS.
 6-18. According to a first embodiment of the means for ending the course
 the end plate (2') of element (2) is constituted by a member (11) which is
 provided with tongues (12). The latter are flexible and during the
 compression conditions shown in FIG. 6 they loosen coming in contact with
 body (13) of the floating shaft (5) but during the conditions of traction
 after the shaft reenters they provide to block the same becoming wedged in
 the tapered portion (14) which is formed in the end of the same shaft as
 shown in FIGS. 6 and 7.
 FIGS. 8 and 12 show in particular the constructive form of member (11) and
 the end of the floating shaft (5).
 A second embodiment of the structure intended to achieve the end of the
 course which is used when it is required to have minimum space as shown in
 FIGS. 14 and 18 consists of providing the flexible tongues (15) totally
 contained in the interior of member (16). Further these tongues engage in
 the interior of the longitudinal cavities (17) which are formed at the end
 of the body of the floating shaft (5).
 Specifically the minimum amount of space of the shock absorbing device is
 obtained with a constructive solution which provides for the flexible
 tongues (15) to be placed in the upper part of member (16) in such a
 manner that the end of the floating shaft (5) remains always in the
 interior of the body of the same floating shaft as shown in FIGS. 15 and
 16.
 Finally as shown in FIGS. 11 and 12 and 17 and 18 the portion of the
 floating shaft (5) which is engaged with members 11 and 16 of the end
 plate (2') has a quadrilateral cross section as shown in FIGS. 12 and 18
 so that the rotations are avoided and the maximum pair of hooking is
 transmitted.
 The location of the device along the pole does not matter from a functional
 point of view. In the case in which the pole is used as a ski pole,
 however, it is preferable to make it integral with the handgrip because in
 this manner the effect of the device on the total inertia moment with
 respect to the wrist is reduced to a minimum.
 It should be noted that the present invention may be used not only with ski
 poles but also for pedestrian excursions or for walking or also for other
 devices used for deambulation such as crutches and similar articles used
 by unfortunate people who need such devices.