Variable-trim frame for two-wheeled vehicles

A variable-trim frame for two-wheeled vehicles has a fork able to connect a handlebar to a hub of a front wheel of the vehicle. A regulating element is provided to rotatably couple the lower portion of the shaft of the handlebar with respective portions of the blades of the fork and destined to make the fork assume a predetermined position in which it is inclined by a relative angle with respect to a perpendicular plane to the ground. A blocking device stabilizes the fork in the predetermined position.

BACKGROUND OF THE INVENTION

The present invention relates to a variable-trim frame for two-wheeled vehicles, in particular for mountain bikes.

It is known that the inclination of the steering tube of the front wheel of a two-wheeled vehicle significantly influences the stability of the vehicle itself. In particular, in a case where the vehicle, for example a bicycle, is about to begin a sharp downhill run, a greater inclination of the axis, as denoted by reference numeral ϕ2inFIG. 1B, enables better control of the means, reducing the risk of tipping over during a steering and braking step. Vice versa, during movement on a flat terrain, an accentuated inclination of the above-mentioned axis is disadvantageous, because it forces the user into a less comfortable position, and makes use of the handlebar more troublesome, as a trim with a less inclined axis is advantageous, as denoted by reference numeral ϕ1inFIG. 1A.

Therefore, the market has a need for a frame for two-wheeled vehicles which enables a user to simply and rapidly vary the angle of inclination of the steering tube of the front wheel to suit the features of the trajectory to be undertaken. In particular, this need is felt in a case of bicycles of the mountain bike type, often used for arduous routes where there are frequent changes of inclination.

SUMMARY OF THE INVENTION

The aim of the present invention is to obviate the above-mentioned drawback, by providing a variable-trim frame which enables a user to simply and rapidly vary the angle of inclination of the steering tube of the front wheel.

In the light of the above aim, a further aim of the present invention is to make available a variable-trim frame of simple conception, with surely reliable function and versatile use, long-lasting and simple to maintain.

In accordance with claim1, a variable-trim frame is described for two-wheeled vehicles, comprising: a fork able to connect a handlebar to a hub of a front wheel of the vehicle; regulating means able to rotatably couple the lower portion of the shaft of the handlebar with respective portions of the blades of the fork and destined to make the fork assume a predetermined position in which it is inclined by a relative angle with respect to a perpendicular plane to the ground; blocking means able to stabilise the fork in the predetermined position.

In accordance with claim12, a frame is described for a two-wheeled vehicle having a variable trim, comprising: a fork able to connect a handlebar to the hub of the front wheel, having an upper shaft connected to the handlebar, and two parallel blades able to accommodate the hub at the respective lower ends thereof; a tubular sleeve, in which the shaft can be housed, passing axially with a variable inclination; a first spherical joint hinge, arranged at the lower end of the sleeve and enabling the shaft to oscillate in a longitudinal plane and at the same time to rotate about a fulcrum point; means associated to the upper end of the tubular sleeve for regulating the angle of inclination of the blade with respect to the sleeve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference toFIGS. 1A, 1Ban2, reference numeral1denotes a two-wheeled vehicle, for example a mountain bike, equipped with the frame of the invention. The frame is provided with a fork2which comprises regulating means5able to rotatably couple the lower portion of the shaft6of the steering of the mountain bike with respective portions of the blades2A,2B of the fork and destined to make the fork2assume a predetermined position in which it is inclined by a relative angle (ϕ1, ϕ2) with respect to a perpendicular plane to the ground.

Blocking means are provided, of which more in the following, able to stabilise the fork in the predetermined position as mentioned above.

With reference toFIG. 2, the regulating means5comprise a lower plate8having two holes (respectively a left hole9A and a right hole9B) crossed by the respective blades2A,2B.

First clamping means (of known type and not illustrated), at the holes9A,98, block the lower plate11to the blades2A,2B.

The central portion of the lower plate8comprises a hole25which is freely and partially involved by the lower end of the shaft.

A pin11fixed in a known way to the walls delimiting the hole25, is positioned perpendicularly to the shaft6of the steering, and freely couples with a first transversal through-hole12, fashioned in proximity of the lower end of the shaft.

In the variant embodiment ofFIG. 2A, the central part of the lower plate8comprises a through-hole81the surface of which extends in a spherical portion82with a growing diameter, proceeding in a top-downwards direction.

The shaft6terminates inferiorly with a head83peripherally delimited by a spherical profiled portion complementary to the spherical portion82of the hole81.

In use conditions of the fork, the head is coupled to the spherical portion82: in this way a spherical node90is constituted which enables the shaft4to oscillate with respect to the plate: see two possible positions W1and W2of the axis of the shaft, indicated inFIGS. 2B and 2C.

The blocking means, with reference toFIGS. 2, 2A, 3, 4, 5A, 5B, 5C, comprise an upper plate13having, in proximity of the lateral ends thereof, two holes (left14A and right14B) crossed by the upper ends of the blades,2A,2B, of the fork2.

The central portion of the shaft19freely crosses a slot15realised in the central portion of the upper plate13.

The upper plate13comprises, in the lower face13D thereof, a cogging16, interrupted by the slot15, the cogs of which are perpendicular to the axes of the holes13A and136. The upper plate13further comprises, at the upper face13U thereof, an undercut17partially contacting the border of the slot15(FIGS. 3, 4).

The holes13A and13B, included in upper plate13, are coaxial to the respective holes11A and11B, realised in the lower plate8.

Further included are second clamping means18, of known type, for blocking the upper plate13to the blades2A.28at the holes13A,13B.

Upper blocking means19and lower blocking means20are included, associated to corresponding portions of the shaft6; these means are respectively overlying and underlying the upper plate13and are able to block the upper plate13.

The upper blocking means19, with reference toFIGS. 5A, 5B, 5C, 10 and 11, comprise a lower block19D and an upper block19U hinged to one another according to an axis that is perpendicular to the axis of the shaft6.

The lower block19D inferiorly comprises a prominence19C slidably coupled to the undercut17of the upper plate13. A first oval through-hole19E, realised centrally in the lower block19D, is crossed by the shaft6.

The upper block19U has a flat upper face19F; a first circular through-hole19G crossed by the shaft6is fashioned centrally in the upper block19U.

Clamping means21are externally associated to the upper terminal portion of the shaft6, and axially press, from the top-downwards, the upper blocking means19against the upper face13U of the upper plate13. The clamping members are constituted, for example, by a hollow cylindrical body21A on the upper terminal portion of which a locking bolt21B locks down the steering of the mountain bike. The lower terminal portion of the hollow cylindrical body21A is in contact with the upper surface19F of the upper block19U.

The lower blocking members comprise a gripping block20A and a stabilising block20B, positioned inferiorly of the gripping block20A, hinged to one another according to a perpendicular axis to the axis of the shaft6.

A cogging20C is provided on a portion of the upper face of the gripping block20A; this cogging couples with the cogged surface16fashioned on the upper plate13(FIGS. 5A, 5B, 5C, 7). A second oval through-hole20D, realised centrally in the gripping block20A, is crossed by the shaft6.

The stabilising block20B has a flat lower face20E and centrally affords a second circular through-hole20F crossed by the shaft6.

It is stressed that the sleeve23of the frame24receiving the central portion of the shaft6identifies, with the upper part thereof, the abutment means which prevent axial movements of the lower blocking means20.

A graduated scale22is advantageously included on the face13U facing upwards of the upper plate13so as to provide the user with an indication of the inclination of the fork2(FIG. 3).

The operating modes of the fork2of the invention, in both the above-considered embodiments, will now be described.

If for example the angle of incidence of the fork2of the mountain bike is equal to ϕ1, in order to change the inclination of the fork2with respect to the ground the user first unblocks the upper blocking members19. It is sufficient to unscrew the screw of the bolt21B blocking the steering: this enables raising the cylindrical body21with a consequent disengagement of the lower portion thereof from the upper surface19F of the upper block19U.

Thereafter the user unblocks the lower blocking means20.

By removing the second clamping means18to unblock the upper plate13from the blades2A,2B: the group defined by the upper plate13, the upper blocking means19and the sleeve23can then be translated upwards to disengage the cogged surface16from the cogging15C of the gripping block20A.

The above-described operations enable the user to manually intervene to oscillate the fork2(and more precisely the group defined by the upper plate13and lower plate10and the blades2A,2B of the fork2) about the axis of the plug11, or about the spherical hinge90(FIGS. 2A, 2B2C), for varying the angular positioning of the group with respect to the ground. Consequently the user can position the fork2so as to be inclined by a predetermined angle (for example ϕ2, as indicated inFIG. 1B), with respect to a plane that is perpendicular to the ground.

It is stressed that the angular travel of the fork2is limited by the abutment of the prominence19C against the rounded terminal portions of the undercut17conformed by the slot15.

To block the fork in the position desired by the user it is necessary to carry out operations that are inverse to those described in the foregoing. The action of the clamping members21and the reciprocal engagement of the cogs conformed by the cogging20C with the cogs of the cogged surface16of the upper plate13enable an effective blocking of the fork2in the desired position.

Having completed the clamping of all the blocking means as described above, the upper blocks19U and the stabilising blocks20B are perpendicular to the shaft6; the lower blocks19D and the gripping blocks20A are inclined as a function of the inclination of the fork2.

An alternative embodiment of the upper blocking means19is illustrated inFIGS. 12, 13, 14, which upper blocking means19comprise: a lower block26(FIG. 14), centrally having an oval through-hole27crossed by the shaft6; an upper block28(FIG. 13), the upper face28A of which is flat, centrally having a relative circular through-hole28B crossed by the shaft6. The lower block26has, at the sides of the upper portion thereof, a pair of semi-circular prominences able to couple with corresponding profiled portions (profiled complementarily to the prominences) fashioned on the lower portion of the upper block28: in this way the blocks26,28are hinged to one another.

A further embodiment of the upper blocking means19is illustrated inFIGS. 15, 16, 17, which upper blocking means19comprise a lower block29(in which an oval through-hole29A crossed by the shaft6is afforded), hinged, by means of a spherical coupling, to an upper block30.

The upper block30is located above the lower block29, has a flat upper face30A and centrally affords a first circular through-hole30B crossed by the shaft6.

FIGS. 18, 19, 20instead illustrate an alternative embodiment of the lower blocking means20. The means comprise: a gripping block31, in which an oval through-hole31A is afforded centrally, crossed by the shaft6, coupled by a spherical coupling, with the gripping block31. The stabilising block32, located below the block30, has a flat lower face32A and centrally has a circular through-hole32B crossed by the shaft6.

A cogging33, conformed on at least a portion of the upper face of the gripping block31, couples with the cogged surface16fashioned on the upper plate13.

It is clear that the variable-trim frame for two-wheeled vehicles, in particular for mountain bikes, enables regulating the angle of incidence of the fork with respect to the ground as a function of the inclination of the ground: it follows that the user can undertake slopes of various inclinations, without the stability of the mountain bike being diminished.

It is then possible for the user to easily and effectively manoeuvre the mountain bike on slopes having various inclinations.

High standards of reliability are also ensured in any use condition.

It is clear that by appropriately sizing the above-described components, it is also possible to use the variable-trim frame on other two-wheeled vehicles, such as, for example, mopeds and/or motorcycles.

With reference to the variant embodiment ofFIGS. 21-32, the shaft6of the steering is connected to the blades2A,2B of the fork2by means of a substantially-hemispherical cap34, as will be more precisely defined in the following.

The shaft6is coaxially inserted in the tubular sleeve23, which has a bushing35at the lower end thereof. The bushing35internally has an annular spherical profiled portion, with a degree of curvature corresponding to that of the cap34, so as to couple therewith to define a first spherical joint hinge36which enables the shaft6to rotate about the longitudinal axis thereof, and at the same time to rotate about the fulcrum X of the spherical joint.

The tubular sleeve23bears at an upper end thereof a second cap37, axially exhibiting a through-hole through which the upper part of the shaft6is inserted. The cap37has a surface, substantially hemispherically shaped, which couples with a complementary lower surface of a second bushing38, to constitute a second spherical joint hinge39. In particular, the opposite spherical surfaces of the cap37and of the bushing38have a centre of curvature coinciding with the fulcrum X of the first spherical joint hinge36.

The shaft6axially exhibits an abutment40, borne by a rotatable support means41, positioned in a seating realised superiorly in the bushing38; the support means41absorbs the axial loads of the shaft6.

The cap37superiorly exhibits a groove42, arranged at a groove43fashioned inferiorly in the bushing38(see in particularFIGS. 23 and 24). The facing grooves42and43identify a seating in which a regulating means44is housed, comprising a first fixed block45, with a threaded through-hole, a second fixed block46, with a threaded through-hole, and a threaded pin47having two threadings in series, oppositely directed. The pin47engages the threaded through-holes of the blocks45and46. The first fixed block45is blocked in the seating of the groove42by means of a transversal blocking pin48. The second fixed block46is blocked in the seating of the groove43by means of a further transversal blocking pin49.

The threaded pin47is axially contacted at an end thereof by a profiled hole which is engaged by an hexagonal key50, for rotation thereof. The profiled hole for regulating is accessible via a through-hole51realised laterally in the bushing38(seeFIG. 24).

The functioning of the variable-trim frame for two-wheeled vehicles of this embodiment is described in the following.

When it is necessary to modify the angle of inclination of the steering tube of the front wheel, the cyclist inserts the special regulating tool, for example the hexagonal key50, in the hole51, and activates the threaded pin47in rotation by means thereof. The pin47has at ends thereof two opposite threadings (seeFIG. 24) and consequently the rotation thereof causes a relative distancing or nearing of the blocks45and46, according to the direction in which the rotation is exerted. The relative distancing of the blocks45and46causes the displacement of the bushing38towards the front part of the bicycle; this causes the oscillation of the shaft6with respect to the fulcrum X, and therefore the reduction of the angle of inclination of the steering tube of the front wheel (seeFIG. 22B). Likewise, the relative nearing of the blocks causes the displacement of the bushing38towards the rear part of the bicycle; this causes the oscillation of the shaft6with respect to the fulcrum X, and therefore the increasing of the angle of inclination of the steering tube of the front wheel (seeFIG. 22C).

In a different embodiment of what is illustrated inFIGS. 23, 24, the cap37superiorly comprises the groove42, open on the side of the cap facing the rear part of the bicycle. The groove42couples with a groove43realised on the facing lower surface of the bushing38. The grooves42and43are engaged by a regulating means44comprising a first fixed block45, with a threaded through-hole, a second fixed block46having a threaded through-hole, and a regulating screw47. The screw engages the threaded through-holes of the blocks45and46. The first fixed block is blocked in the groove42(FIG. 25) by means of a transversal blocking pin48. The second fixed block is blocked in the seating of the groove43by means of a transversal blocking pin49. The regulating screw exits laterally from the hinge39and at the free end has a knob52for facilitating grip and manoeuvring thereof.

To vary the angle of inclination of the steering tube of the front wheel, the user rotates the regulating knob52; this sets the screw47in rotation (seeFIG. 23) which has two opposite threadings, able to respectively engage the first block45and the second block46; the rotation of the screw47causes the relative distancing or nearing of the blocks45and46, according to the rotation direction. The relative distancing of the blocks causes the displacement of the bushing38towards the front part of the bicycle; this causes the oscillation of the shaft6with respect to the fulcrum X, and therefore the reduction of the angle of inclination of the steering tube of the front wheel. The relative nearing of the blocks45and46brings about the increase of the angle of inclination of the steering tube of the front wheel.

The inclination of the steering tube of the front wheel is visualised by means of a graduated scale53, associated to a fixed index, engraved respectively on the cap37and on the bushing38: seeFIG. 26.

A further embodiment of the invention is illustrated inFIGS. 30 and 31; the bushing38inferiorly comprises a seating54which receives the regulating means44. The regulating means comprise: a grub screw55which enmeshes with a cogged sector56, centred on the fulcrum point X. The cogged sector is installed internally of the cap37at the seating54by known means that are not illustrated.

The grub screw55, supported in the seating54by bushings57, is axially constrained to the bushing38by means of the abutments58and59, included on the non-threaded part of the grub screw, interposed between the bushings57; thus axial play between the grub screw and the bushing38is eliminated.

The grub screw55comprises, at the projecting end of the bushing, a knob60; alternatively a profiled hole can be included, not illustrated, in which a hexagonal key engages.

It is stressed that the grub screw-cogged sector coupling is not reversible.

To regulate the angle of inclination of the steering tube of the front wheel, the cyclist rotates the knob60to activate the grub screw55in rotation, which, being engaged with the cogged sector56, determines the oscillation of the bushing38with respect to the fulcrum point X and the consequent relative displacement of the bushing with respect to the cap37; this causes the oscillation of the shaft6with respect to the fulcrum X, and therefore the change of the angle of inclination of the steering tube of the front wheel.

In a further embodiment, illustrated inFIGS. 27A-27B-27C, 28A-28B and 29A-29B(which is interchangeable with the preceding embodiment ofFIGS. 22A, 22B22C), the tubular sleeve23receives, in the upper end thereof, the lower part of a first plate-shaped element61having a slot62crossed by the upper part of the shaft6. The first plate-shaped element61comprises, on the upper head, a grooved surface63having constantly-pitched grooves, interrupted by the slot62which engages with a corresponding grooved surface64realised in the lower face of a second plate-shaped element65which axially comprises a slot66, through which the upper part of the shaft6freely transits; a seating67, spherically profiled, is made in the upper face of the element65.

A bushing68, the external surface69of which is complementary with respect to the surface of the seating67, axially comprises a through-hole70for insertion of the shaft6. At the annular portion of the upper surface68A thereof, the bushing68restingly receives an overturned cup-shaped element71which comprises a seating72that receives the upper end of the shaft6. The bushing68comprises a hole72, at the upper end, through which a screw73passes. The screw engages with a threaded hole74axially afforded on the upper end of the shaft6; this enables actuating the axial locking of the overturned cup-shaped element71, the bushing68, and the second plate-shaped element66with respect to the first plate-shaped element61.

In the illustrated embodiment, when it is necessary to modify the angle of inclination of the steering tube of the front wheel, the user loosens the screw73and lifts the overturned cup-shaped element71as illustrated inFIG. 27Bso as to disengage the grooved surface64of the second plate-shaped element65from the grooved surface63of the first plate-shaped element61.

The above-described operations enable the user to manually oscillate the shaft6about the fulcrum X, enabling varying the angular positioning of the fork with respect to the vertical plane parallel to the advancement direction of the bicycle.

Consequently the user can appropriately position the fork2so as to be inclined by a predetermined angle (for example, as indicated inFIG. 27C), with respect to a plane that is perpendicular to the ground.

The angular travel of the fork2is limited by the contact of a portion of the surface of the shaft6with a portion of the internal surface64of the slot62of the first plate-shaped element61.

The operations for blocking the fork in the user's desired position are inverse to those described in the foregoing.

The variable-trim frame according to the variants ofFIGS. 21-31therefore attains the aim of enabling the user to rapidly and easily vary the angle of inclination of the steering tube of the front wheel of the bicycle.

In particular, according to the embodiments illustrated inFIGS. 23-24, 25-26 and 30 and 31it is possible to vary the angle of inclination of the frame simply by operating the rotation of a special tool, such as a grub screw, or according to the embodiment of the present invention illustrated inFIGS. 27A-27B-27C, 28A-28B-28C and 29A-29Bby simply loosening a screw, the raising of an overturned cup-shaped element and the manual oscillation of the steering tube of the steering.

An advantageous aspect of the invention is constituted by the fact that the regulation of the trim of the frame is obtainable with great precision so as to ensure, in all riding conditions, the preferential trim of the two-wheeled vehicle; in particular according to the embodiments of the present invention illustrated inFIGS. 23-24, 25-26, and 30 and 31, the regulation is obtainable continuously within an appropriate range of variability, while the second embodiment illustrated inFIGS. 27A-27B-27C, 28A-28B-28C and 29A-29Bthe regulation can be obtained discretely within an appropriate range of variability, with a resolution corresponding to that of the pitch between the grooves of the grooved surface.

FIG. 32is alike the solution illustrated inFIGS. 22A, 22B, 22C, relating to a different specification of the fork, conformed with the blades2A,2B joined in proximity of the upper end by means of a plate76, details G1and G2have the same technical-functional characteristics of the details as inFIGS. 22A, 22B, 22C.

The detail of the frame illustrated inFIG. 32can be used in a coupling with any one of the hinge devices for the regulation of the inclination of the axis of the frame of the present invention and illustrated inFIGS. 23-24, 25-26, 30-31.

It is understood that the above has been described by way of example and that any constructional variants are considered to fall within the protective scope of the invention as claimed in the following.