WO2018198141A1

WO2018198141A1 - Mechanism for generating a motion of rotation with double thrust lever having variable arm

Info

Publication number: WO2018198141A1
Application number: PCT/IT2017/000083
Authority: WO
Inventors: Enrico VOLTAZZA; Fabio VOLTAZZA; Michela VOLTAZZA
Original assignee: Pressofusione Saccense Srl
Current assignee: Pressofusione Saccense Srl
Priority date: 2017-04-24
Filing date: 2017-04-24
Publication date: 2018-11-01
Anticipated expiration: 2019-10-24

Abstract

The present invention relates to a mechanism for generating a rotation movement with double thrust lever having variable arm, comprising two thrust levers 11, 12, each of which is associated at a first end portion 11' to a common rotation pin 2 so as to be rotationally integral with said pin with respect to the rotation axis XI of the pin and bears at a second end portion thereof 11" a thrust appendage 13, 14 which is hinged to the thrust lever and is destined to receive an external force suitable to determine the rotation movement of the lever. Each thrust lever has a variable length so that during the rotation movement around the common rotation pin 2 the arm B, defined by the distance between the respective thrust appendage and the rotation axis XI, can vary. The mechanism comprises for each thrust lever, a kinematic guide element suitable to guide the variation movement in length. Each kinematic guide element consists of an elongated body 111 which is associated at a first end portion 1111 to the pin in a rotationally neutral manner and which bears at its second end portion 111", opposite the first, a rotating support body 112 or 212, rotatably associated to the elongated body 111 at the second end portion to rotate around a second axis X2 parallel to the axis of rotation XI of the pin 2. The thrust appendage is rigidly attached to the rotating support body in a radially eccentric position with respect to the second axis X2 so as to kinematically associate the kinematic guide element to the respective thrust lever.

Description

DESCRIPTION

"Mechanism for generating a motion of rotation with double thrust lever having variable arm"

FIELD OF APPLICATION

[0001] The present invention relates to a mechanism for generating a rotation movement with double thrust lever having variable arm.

[0002] In particular, this mechanism may find application in the movement mechanism of a bicycle. Advantageously, the mechanism according to the invention may also find other applications involving generating a rotation movement through two pedal cranks or hand cranks, for instance in nautical craft such as pedal boats or in double crank winches .

STATE OF THE ART

[0003] A known mechanism for generating a rotation movement with double thrust lever comprises two rods, each of which forms a thrust lever. Each rod is secured at a first end portion to a rotation pin around which the rotation movement develops and bears associated to a second end portion, opposite the first, a thrust appendage which is destined to receive an external force suitable to determine the rotation movement of the rod and of the associated rotation pin. The two thrust rods are keyed to the two opposite ends of the same hub or rotation pin, to extend in length (orthogonally to the axis of rotation) in diametrically opposite positions relative to one another. The motion generated by the rotation of the rods and of the rotation pin is transmitted by transmission means kinematically connected to the rotation pin or to one of the rods, for example by means of a toothed wheel/ chain assembly. The complete rotation motion of each rod is divided into two phases (each extending to about a half- revolution) : a thrust phase, in which the rod and the relative thrust appendage are active in generating the movement, and a recovery phase, in which the rod and the relative thrust appendage are passively dragged in rotation by the movement of the other rod (which is in the thrust phase) until brought back to the thrust phase once again.

[0004] The rotation speed is a function of the thrust impressed to the rod and the length (or arm) of said rod, understood as the distance between the rotation pin and the thrust appendage. The rotation speed can be varied only by varying the thrust impressed on the rod. It is in fact not possible to vary the arm, that is, the length of the rod, this being made in one single piece. This embodiment is dictated by requirements of mechanical robustness and simplicity of construction. The realization of a variable arm mechanism would in fact be too complex both from a construction point of view, and from a point of view of operational management understood as the adaptation of the length of the arm to operational needs.

[0005] A typical application of the generation mechanism described above is in the bicycle. The mechanism comprises two pedal cranks (rods) , each of which bears at its end a pedal (thrust appendage) . The two pedal cranks are keyed to the two opposite ends of a hub, to extend in length in diametrically opposite positions relative to one another. A toothed wheel is associated to one of the two cranks, on which wheel the driving belt to the rear wheel is kinematically associated. The complete rotation of each pedal crank divides into two phases: a thrust phase and a recovery phase.

[0006] As is known, the pedal cranks are in one piece and rigid. Assuming no change of the gear ratio, the rotation speed can be changed only by changing the thrust impressed on the pedals, as it is not possible to vary the arm of the pedal crank.

[0007] To date mechanisms for generating a rotation movement with double thrust lever having variable arm characterized by mechanical robustness (i.e. reliability) and simple construction, and which can therefore be exploited on a mechanically simple application such as bicycles, pedal boats or winches, without interfering in the regularity of pedalling or, in general, the rotation movement are not available .

PRESENTATION OF THE INVENTION

[0008] Consequently, the purpose of the present invention is to eliminate entirely or in part the drawbacks of the prior art mentioned above, by providing a mechanism for generating a rotation movement with double thrust lever having variable arm which is operationally reliable and at the same time simple to construct.

[0009] A further purpose of the present invention is to make available a mechanism for generating a rotation movement with double thrust lever having variable arm, which allows the application of the external thrust force on a point that moves along a circular or substantially circular trajectory.

[0010] A further purpose of the present invention is to make available a mechanism for generating a rotation movement with double thrust lever having variable arm which can replace the traditional pedal crank/pedal generation mechanism of a bicycle, allowing the rider to further exploit the thrust impressed during the active rotation phase of each pedal, without interfering in the regularity of pedalling.

DESCRIPTION OF THE DRAWINGS

[0011] Further characteristics and advantages of the present invention will be more clearly understandable from the description given below of its preferred and non-limiting embodiments, wherein:

[0012] -Figure 1 shows a schematic view of a mechanism for generating a rotation movement with double thrust lever having variable arm according to a first preferred embodiment of the invention, shown in an installation condition on a bicycle;

[0013] - Figure 2 shows four different positions adopted by a thrust lever with the relative thrust appendage and with the relative kinematic guide element in the mechanism for generating a rotation movement according to a first embodiment of the invention, respectively in the circular movement a first position being shown at 3 o'clock, a second at 6 o'clock, a third at 9 o'clock and a fourth position at 12 o'clock;

[0014] -Figure 3 shows an orthogonal cross-section view of the thrust lever with the relative thrust appendage and with the relative kinematic guide element shown in Figure 2 according to the cross-section plane III-III indicated therein;

[0015] -Figure 4 shows a cross-section orthogonal view of the thrust lever illustrated in figure 2, along the cross- section plane IV-IV indicated in figure 3;

[0016] -Figure 5 shows a cross-section view of the kinematic guide element illustrated in figure 2, along the cross- section plane V-V indicated in figure 3;

[0017] -Figure 6 shows an enlarged view of the thrust lever with the relative thrust appendage and with the relative kinematic guide element shown in Figure 2 in the 3 o'clock position;

[0018] - Figure 7 shows a rear perspective view of the thrust lever shown in Figure 6;

[0019] -Figure 8 shows an enlarged view of the thrust lever with the relative thrust appendage and with the relative kinematic guide element shown in Figure 2 in the 6 o'clock position;

[0020] - Figure 9 shows a rear perspective view of the thrust lever shown in Figure 8;

[0021] -Figure 10 shows an enlarged view of the thrust lever with the relative thrust appendage and with the relative kinematic guide element shown in Figure 2 in the 9 o'clock position;

[0022] - Figure 11 shows a rear perspective view of the thrust lever shown in Figure 10;

[0023] -Figure 12 shows an enlarged view of the thrust lever with the relative thrust appendage and with the relative kinematic guide element shown in Figure 2 in the 12 o'clock position;

[0024] - Figure 13 shows a rear perspective view of the thrust lever shown in Figure 12;

[0025] - Figure 14 shows four different positions adopted by a thrust lever with the relative kinematic guide element and with the relative thrust appendage in a mechanism for generating a rotation movement according to a second embodiment of the invention, respectively in the circular movement a first position being shown at 3 o'clock, a second at 6 o'clock, a third at 9 o'clock and a fourth position at 12 o'clock;

[0026] - Figure 15 shows an orthogonal cross-section view of the thrust lever with the relative kinematic guide element and with the relative thrust appendage, shown in Figure 14 according to the cross-section plane XV-XV indicated therein;

[0027] - Figure 16 shows a cross-section orthogonal view of the thrust lever illustrated in figure 14 according to the cross-section plane XVI-XVI indicated in figure 15;

[0028] - Figure 17 shows a cross-section view of the kinematic guide element illustrated in figure 14 according to the cross-section plane XVII-XVII indicated in figure 15;

[0029] - Figures 18 and 19 show two different perspective views of the thrust lever with the relative kinematic guide element and with the relative thrust appendage, shown in Figure 14 in the position at 3 o'clock; [0030] - Figure 20 shows a front orthogonal view of the thrust lever with the relative kinematic guide element and with the relative thrust appendage, shown in Figure 14 in the position at 9 o'clock;

[0031] - Figure 21 shows an orthogonal cross-section view of the thrust lever with the relative thrust appendage and with the relative kinematic guide element, shown in Figure 20 according to the cross-section plane XXI-XXI indicated therein;

[0032] - Figure 22 shows a perspective view of the thrust lever with the relative kinematic guide element and with the relative thrust appendage, shown in Figure 14 in the position at 9 o'clock;

[0033] - Figures 23 and 24 show two different perspective views of the main components that form the kinematic guide element shown in the Figures 18 and 19;

[0034] - Figure 25 shows an exploded perspective view of the main components that form the thrust appendage shown in the Figures 18 and 19;

[0035] - Figure 26 shows an exploded perspective view of two main components that form the thrust lever shown in the Figures 18 and 19; and

[0036] - Figure 27 shows two perspective views of the support base shown in the Figures 18 and 19.

DETAILED DESCRIPTION [0037] With reference to the above drawings, reference numeral 1 globally denotes a mechanism for generating a rotation movement with double thrust lever having variable arm according to the present invention.

[0038] As will be explained in the rest of the description, the mechanism 1 according to the invention finds particular application as a movement mechanism of a bicycle.

[0039] The mechanism 1 according to the invention may also find other applications different from a bicycle, involving the generation of a circular movement through two pedal cranks or hand cranks, such as a handbike, recumbent trike or recumbent bike, in nautical craft such as pedal boats, or in double crank winches.

[0040] According to a general embodiment of the invention, the mechanism for generating a rotation movement with double thrust lever having variable arm 1 comprises two thrust levers 11 and 12.

[0041] As shown in the appended drawings, each thrust lever 11, 12 is associated at a first end portion 11' to a rotation pin 2, around which the aforementioned rotation movement develops so as to be rotationally integral with said pin 2 relative to the rotation axis XI of the pin.

[0042] Each thrust lever 11, 12 bears at a second end portion thereof 11", opposite the first, a thrust appendage 13, 14 which is destined to receive an external force such as to determine the rotation movement of the lever 11, 12.

[0043] The two thrust levers 11 and 12 are fixed to two opposite ends of the same common rotation pin 2 to extend in length, orthogonally to the rotation axis XI of the pin 2, in diametrically opposite positions with respect to the rotation axis XI. Their movement is thus in phase opposition, always staggered by 180°.

[0044] Operationally, the complete rotation movement of each thrust lever 11, 12 is divided into two phases, each corresponding to about one half revolution (about 180°):

[0045] - a thrust phase, in which the thrust lever 11 or 12 is active in the generation of motion; and

[0046] - a recovery phase, in which the thrust lever 11 or 12 is dragged passively by the rotation movement of the other lever 12 or 11, which works in phase opposition.

[0047] According to a first aspect of the invention, each thrust lever 11, 12 has a variable length so that during the rotation movement of the thrust lever 11, 12 around the common rotation pin 2 the arm B, defined by the distance between the thrust appendage 13, 14 and the rotation axis XI of the pin 2, can vary.

[0048] According to a further aspect of the present invention, the mechanism 1 comprises, coupled to each thrust lever 11, 12, a kinematic guide element suitable to guide the movement of variation in length of the coupled thrust lever 11, 12.

[0049] Each of the kinematic guide elements is constituted by an elongated body 111, which is associated at a first end portion 111' to said common rotation pin 2 in a rotationally neutral manner around the axis of rotation XI.

[0050] The rotationally neutral connection prevents the kinematic guide element from transferring thrust to the rotation pin 2 by means of the relative elongated element 111. Only the thrust lever 11, 12 is suitable to transfer to the rotation pin the force impressed on the thrust appendage 13, 14 as the angular momentum of rotation.

[0051] Advantageously, the kinematic guide element is associated to the rotation pin 2 by means of a rotatable connection with anti-friction means.

[0052] As shown in the appended drawings, the elongated body

111 of each kinematic guide element bears at its second end portion 111", opposite the first, a rotating support body 112 or 212, rotatably associated to the elongated body 111 at the second end portion 111" to rotate around a second axis X2 parallel to the axis of rotation XI of the common pin 2.

[0053] Preferably, the aforesaid rotating support body

112 or 212 is associated to the elongated body 111 by anti- friction means 113 or 213, such as bearings, ball or roller bearings or lubricating gaskets.

[0054] The thrust appendage 13, 14 of each thrust lever 11, 12 is rigidly fixed to the rotating support body 112 or 212 of the respective kinematic guide element in a radially eccentric position with respect to the second axis X2 so as to associate kinematically the kinematic guide element to the respective thrust lever 11, 12 by means of the aforesaid rotating support body 112.

[0055] In the appended figures, the attachment point of the thrust appendage 13, 14 on the rotating support body 112 or 212 is indicated as X3. The rigid attachment of the thrust appendage 13, 14 to the rotating support body 112 or 212 is aimed to prevent a relative rotation between the two parts and thus make them integral in rotation.

[0056] Preferably, each thrust appendage 13, 14 engages the rotating support body 112 or 212 of the respective kinematic guide element in a direction parallel to the axis of rotation XI of the pin 2.

[0057] Preferably, the rotation plane of each thrust lever 11, 12 is parallel to the rotation plane of the respective kinematic guide element. In particular, the rotation plane of each of the thrust levers 11, 12 is perpendicular to the axis of rotation XI of the pin 2.

[0058] According to a first embodiment shown in the figures from 1 to 13, and in particular in the figure 5, the elongated body is constituted by a rod 111 provided at the second end portion 111" with a circular ring 114. The rotating support body is constituted by an annular flange 112 which is rotatably inserted (in order to rotate around said second axis X2) inside said circular ring 114 made at the second end portion 111" of the rod which defines the elongated body 111. The thrust appendage 13, 14 of each thrust lever 11, 12 is rigidly fixed to said annular flange 112 (that constitutes the rotating support body) in a position radially eccentric with respect to said second axis X2 around which said annular flange rotates, in such a way to kinematically associate the kinematic guide element to the respective thrust lever 11, 12 by means of said annular flange 112.

[0059] Preferably, as shown in particular in the figure 5, said elongated body 111 is provided at its own first end 111' with a second circular ring 115, by means of which the elongated body 111 is rotatably associated to the rotation pin 2.

[0060] According to a second embodiment shown in the figures from 14 to 25, the elongated body is defined by a rod 111, while the rotating support body is constituted by an extension 212 which is rotatably associated to the rod 111 in correspondence of the second end 111" of such elongated body 111 in order to rotate around said second axis X2. The thrust appendage 13, 14 of each thrust lever 11, 12 is rigidly fixed to said extension 212 (that constitutes the rotating support body) in a distanced position with respect to the second axis X2, around which said extension rotates with respect to the elongated body 111, in such a way to kinematically associate the kinematic guide element to the respective thrust lever 11, 12 by means of said extension 212. Functionally, the assembly of rod 111 and of extension 212, which are hinged one to each other around the second axis X2 and define jointly the kinematic guide element, forms a mechanism of piston rod / crank type for transforming a rectilinear movement into a circular movement and vice versa, wherein the rod 111 defines the piston rod and the extension 212 defines the crank.

[0061] In particular, as shown in the Figures 15 and 23, the extension 212 is constituted by a shaped plate, which is provided:

[0062] - at a first end 212' with a circular through hole 212a, which is destined to receive inside (with interposition of friction means 213) a pin 111a of the elongated body 111 in order to rotatably connect the extension around the second axis X2 on the elongated body 111;

[0063] - at a second end 212" with a projecting pin 212b in correspondence of which the thrust lever 11, 12 is rotatably connected to the extension 212 and in correspondence of which the thrust appendage 13, 14 is rigidly fixed to the extension 212 by means of a fixing body 133.

[0064] Operationally, as shown schematically in figure 2 and in figure 14, during the rotation of the thrust lever 11, 12 around the pin 2 - thanks to the rotation of the rotating support body (annular flange 112 or extension 212) around the second axis X2 and to the positioning eccentricity E of the thrust appendage 13, 14 with respect to the second axis X2 - the thrust appendage 13, 14 performs a complete circular motion (illustrated with the circumference C2) , eccentric with respect to the rotation axis XI of the pin 2, the centre 0 of which is radially shifted toward the arc of circumference corresponding to the thrust half- revolution made by the kinematic guide element around the axis XI of the pin 2. In the Figures 2 and 14 the circumference that describes the circular movement of the kinematic guide element (or rather of the centre X2 of the rotating support body 112 or 212) is indicated as CI.

[0065] The Figures 2 and 14 refer in particular to the case where the mechanism 1 is inserted in a bicycle: the arrow A indicates the direction of advancement of the bicycle; the arrows R indicate the direction of rotation of the thrust lever 11, 12. [0066] The thrust appendage 13, 14 - in its movement of rotation around the axis X2 integrally with the rotating support body 112 or 212 - drags alternately in axial lengthening and axial shortening the respective thrust lever 11, 12 imposing on the second end 11" of the thrust lever 11, 12 a circular movement. As can be seen in the Figures 2 and 14, this movement brings the thrust lever 11, 12 to oscillate alternately with respect to the longitudinal axis of the elongated body 111 of the kinematic guide element around the axis XI.

[0067] This way, in the thrust phase (i.e. when the thrust lever 11, 12 is active and generates motion) upon the varying of the angular position around the rotating support body 112 or 212, the arm B (defined by the distance between the attachment point X3 of the thrust appendage 13, 14 on the rotating support body 112 or 212 and the rotation axis XI of the pin 2) progressively increases up to a maximum value equal to the sum of the eccentricity E with the distance D between the axis X2 and the axis XI (see figures 6 and 7 for the first embodiment; Figures 16 and 18 for the second embodiment) . As can be seen in the Figures 2 and 14, this maximum value is reached in about half of the thrust half-revolution; having exceeded this maximum, the lever value B starts to decrease again.

[0068] In the recovery phase (i.e. when the thrust lever is dragged and generates no motion) upon the varying of the angular position around the rotating support body 112 the arm B progressively decreases to a minimum value equal to the distance D between the axis X2 and the axis XI of the pin 2 less the eccentricity E (see figures 10 and 11 for the first embodiment; Figures 20 and 22 for the second embodiment) . As can be seen in the Figures 2 and 14, this minimum value is reached in about half of the recovery half-revolution; having exceeded this minimum, the lever value B starts to increase again.

[0069] This way, in the mechanism 1 according to the invention, in the thrust phase (i.e. when the rod is active and generates motion) being the force applied to the thrust appendage 13, 14 equal, a greater speed is obtained thanks to the increased arm B of the thrust lever. Conversely, in the recovery phase (i.e. when the rod is dragged and generates no motion) , the arm B of the thrust lever is reduced .

[0070] In the appended figures, the distance between the second axis X2 of the rotating support body 112 or 212 and the rotation axis XI of the pin 2 is indicated as "D", while the eccentricity of the attachment point X3 of the thrust appendage on the rotating support body is indicated as "E". For the purposes of the present invention, the attachment point X3 of the thrust appendage on the rotating support body can be considered substantially coincident with the point where the thrust received by the thrust appendage 13, 14 is discharged onto the thrust lever 11, 12.

[0071] In the Figures 2 and 14, the mechanism 1 according to the invention is illustrated with the thrust phase which corresponds to the position adopted in the 3 o'clock position (maximum value of the arm) and with the recovery phase which corresponds, instead, to the position adopted by the thrust appendage 13 in the 9 o'clock position (minimum value of the arm) . The other two positions (12 o'clock and 6 o'clock) illustrate the thrust lever (with relative thrust appendage and kinematic guide element) in the two positions of passage respectively from the recovery phase to the thrust phase and from the thrust phase to the recovery phase.

[0072] The thrust appendage 13, 14 naturally adopts the positions described above, in the thrust phase and in the recovery phase, thanks to the free rotation of the rotating support body 112 or 212 and to the fact that the thrust appendage 13, 14 cannot rotate with respect to the rotating support body 112 or 212.

[0073] More specifically, the application of the force on the thrust appendage during the thrust phase tends to move the same appendage 13, 14 outwards and downwards, thereby favouring the direction of rotation of the second end 11" of the thrust lever around the rotating support body and its elongation. During the recovery phase, the thrust appendage does not substantially undergo the application of external force to the mechanism. This allows the appendage and the rotating body to follow the same circular trajectory started by the appendage in the thrust phase.

[0074] From all this it derives that »a mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention allows the application of the external thrust force on a point (thrust appendage) that moves along a circular or substantially circular trajectory.

[0075] According to an embodiment of the invention not illustrated in the appended figures, each thrust lever 11, 12 is variable in length thanks to the fact of having an extensible telescopic structure which extends axially along the longitudinal axis of said lever.

[0076] According to an alternative embodiment of the invention not shown in the appended figures, each thrust lever 11, ,12 is variable in length not thanks to one own telescopic structure, but thanks of being slidingly associated to said rotation pin 2 or to the respective thrust appendage 13, 14 in parallel to the longitudinal extension axis of the same lever. The sliding stroke of the thrust lever with respect to the rotation pin 2 or to the respective thrust appendage 13, 14 determines the variation in length of the arm B of the thrust lever.

[0077] According to the first embodiment of the invention illustrated in the figures from 1 to 13, each thrust lever 11, 12 is axially rigid and is variable in length thanks to the fact of being slidingly associated to the rotation pin 2 parallel to the longitudinal extension axis of said lever. The sliding stroke of the thrust lever with respect to the rotation pin determines the variation in length of the arm B of the thrust lever. Preferably, the thrust lever is equipped in this case with a limit stop 19.

[0078] According to the second embodiment of the invention illustrated in the figures from 14 to 25, each thrust lever 11, 12 is axially rigid and is variable in length thanks to the fact of being slidingly associated to the respective thrust appendage 13, 14 in parallel to the longitudinal extension axis of the same lever. The sliding stroke of the thrust lever with respect to the respective thrust appendage 13, 14 determines the variation in length of the arm B of the thrust lever.

[0079] The thrust lever 11, 12 can be attached indirectly to the rotation pin 2 by means of a support base 15, as illustrated in particular in the figure 3.

[0080] Preferably, when a support base 15 is envisaged, as shown in the figures 4 and 10, the thrust lever 11, 12 is slidingly associated to the rotation pin 2 by means of said support base 15, in such a way to make the assembly thereof on the rotation pin 2 easier.

[0081] Advantageously, as shown in particular in figure 3 (first embodiment) , also the kinematic guide element 111, 112 may be indirectly associated to the rotation pin 2 by said support base 15, although in a manner such as to ensure a neutral rotatable connection to the rotation pin. Alternatively, the kinematic guide element can be attached directly to the rotation pin 2.

[0082] The thrust lever 11, 12 can be fixed directly to the rotation pin, for example by means of direct keying, as shown in particular in Figure 15. In this case too, a support base 15 can be envisaged. However, such support base 15 is an integral part of the same thrust lever and is integral to the latter. In such a case, the thrust lever 11, 12 is rigidly fixed to the rotation pin 2 by means of the support base 15.

[0083] Preferably, when the thrust lever 11, 12 is fixed directly and rigidly to the rotation pin and is provided with a support base 15 integral with the same thrust lever, the kinematic guide element 111, 112 can be associated indirectly to the rotation pin 2 by means of the same thrust lever 11, 12 in the portion into which the latter is keyed on the rotation pin (i.e. on said integral support base 15) , as shown in particular in Figure 15 (second embodiment) . In such a case, the connection of the kinematic guide element to the thrust lever is idle, in such a way to provide that the kinematic guide element is connected in a manner rotatably idle to the rotation pin.

[0084] Advantageously, as shown in particular in the Figures 15 and 21, the support base 15 integral to the thrust lever is provided with a seat 25 for rotatably connecting the elongated body 111. As shown in particular in Figure 24, the elongated body 111 is provided at its own first end 111' with a circular clamp 26, diametrically openable, which allows an easy connection at said seat 25.

[0085] Preferably, as envisaged in the two embodiments illustrated in the appended figures, each of thrust levers

11, 12 is defined by two rods 16, 17 which are parallel to the longitudinal extension axis of the thrust lever 11,

12. Preferably, the two rods 16, 17 are fixed to the rotation pin 2 o to the relative thrust appendage 13, 14 in such a way that the rotation axis XI is placed on the centreline between said two rods. This way there is a balanced distribution of the forces.

[0086] More specifically, according both to the first embodiment and to the second embodiment, said two rods 16, 17 are connected to each other: [0087] - at the first end 11' of the thrust lever 11, 12 by means of the aforesaid support base 15; and

[0088] - at the second end 11" of the thrust lever by means of a fork body 18, to which the respective thrust appendage 13,14 is also rotatably hinged.

[0089] According to the first embodiment, illustrated in particular in the figures 3 and 4, the two rods 16, 17 are slidingly associated to the support base 15, so that the thrust lever can vary its length and thus the arm offered by it. Alternatively, the variation in length of the thrust lever may be obtained by equipping both rods 16, 17 with an axial telescopic structure.

[0090] According to the second embodiment, illustrated in particular in the figure 16, the two rods 16, 17 are slidingly associated to the aforesaid fork body 18, so that the thrust lever can vary its length and thus the arm offered by it. Alternatively, the variation in length of the thrust lever may be obtained by equipping both rods 16, 17 with an axial telescopic structure.

[0091] According to an alternative embodiment not illustrated in the appended figures, each thrust lever 11, 12 can be defined by a single rod. The variation in length of the thrust lever may be obtained by connecting the single rod slidingly to the rotation pin (preferably by means of a support base) or to the thrust appendage, or by equipping the single rod with an axial telescopic structure .

[0092] According to the first embodiment, the elongated body 111 and the annular flange 112 (that form together the kinematic guide element) lie on the same plane and moves on such a common plane. In other words, the elongated body 111 and the rotating support body 112 (annular flange) are integrated between them, in such a way to reduce the thickness of the kinematic guide element in the direction of the axis XI and X2. In such a case, the kinematic guide element 111 and 112 can be interposed between the thrust lever 11, 12 and the respective thrust appendage 13, 14. This is possible since the kinematic guide element, and in particular the elongated body 111, cannot hinder the thrust appendage 13, 14 with its movement.

[0093] Advantageously, in the case in which (as described above) the kinematic guide element 111 and 212 is placed near to the thrust appendage 13, 14, the rotating support body 112 (annular flange) can be made in one piece with the respective thrust appendage 13, 14, since in this case the position of the kinematic guide element does not make the connection between thrust lever and thrust appendage difficult.

[0094] According to the second embodiment, the elongated body 111 and the extension 212 (that form together the kinematic guide element) lie on two different (parallel) planes and move on such two parallel and different planes. In other words, the elongated body 111 and the rotating support body 212 (extension) are superimposed one to each other in parallel. Compared to the embodiment with annular flange 112 integrated in the elongated body 111, such embodiment causes the thickness of the kinematic guide element to increase in the direction of the axis XI and X2. In this case, preferably, the kinematic guide element 111 and 212 is not interposed between the thrust lever 11, 12 and the respective thrust appendage 13, 14, since the elongated body 111 could interfere in the thrust appendage 13, 14 with its movement. In this case, preferably (as shown in particular in the figure 15 and 21) it is the thrust lever 11, 12 to be interposed between the kinematic guide element 111 and 212 and the respective thrust appendage 13, 14.

[0095] Advantageously, the kinematic guide element made according to the second embodiment can be made with an elongated body 111 having dimensions more limited both in length and in width with respect to the elongated body 111 of the first embodiment. In fact, in the second embodiment the elongated body 11, diversely from what envisaged in the second embodiment, does not have the rotating support body integrated in it. This makes the kinematic guide element made according to the second embodiment less cumbersome as a whole.

[0096] Advantageously, the mechanism 1 according to the invention comprises transmission means of the rotation movement generated by the two thrust levers 11 and 12 on the rotation pin 2. The aforesaid transmission means of the movement can be kinematically associated directly to the rotation pin 2 or to one of the two thrust levers 11 or 12. These transmission means may be of any type suitable for the purpose and are not described here since they are known to a person skilled in the art. By way of example they may consist of a toothed crown concentric with the axis of rotation XI of the pin and by a chain or belt transmission kinematically coupled to the toothed wheel.

[0097] The mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention is particularly suitable to be used in applications that provide for the application of force by a human.

[0098] In the case in which the force applied to the thrust appendages is applied by means of the feet of a user, the two thrust levers 11, 12 are pedal crank and the relative thrust appendages 13, 14 are pedals.

[0099] A particularly preferred application of the mechanism 1 according to the invention is in bicycles and in general in pedal-operated vehicles. Figure 1 shows a frame S of a bicycle, where P indicates the toothed crown and Q the transmission chain. The arrow A indicates the direction of advancement of the bicycle, while the arrows R indicate the direction of rotation of the thrust lever/ pedal crank.

[00100] Considering the characteristics set out above, the mechanism 1 according to the invention is suitable very well to replace the traditional pedal crank/pedal mechanisms having a fixed arm pedal crank and pedal rotating with respect to the pedal crank. In fact, compared to the aforesaid traditional mechanisms the mechanism 1 according to the invention allows the cyclist, being the force applied equal, to increase the speed thanks to the increase of the arm in the thrust phase. At the same time, the regularity of pedalling is not substantially influenced by the mechanism 1 given that the pedals (thrust appendages) follow a circular or substantially circular trajectory.

[00101] In other words, the mechanism 1 according to the invention allows the cyclist to perform regular and traditional pedalling, but to exercise a variable thrust action, more intense in the thrust phase, further exploiting the thrust impressed on the pedal.

[00102] Typically, a conventional pedal crank has a useful length/arm (distance between pin/hub and the pedal axis) of about 170 mm. Thanks to the invention, the pedal crank/ thrust levers 11, 12 of the mechanism 1 according to the invention in the thrust phase can increase the useful arm by about 60 - 80 mm, bringing the useful arm to 230-250 mm. In the recovery phase, the pedal cranks/ thrust levers 11, 12 of the mechanism 1 according to the invention shorten the arm by about 60 - 80 mm.

[00103] What has been described above in relation to the application of the mechanism 1 on a bicycle, in terms of benefits and construction features, is understood as automatically extended - mutatis mutandis - to other applications .

[00104] The present invention relates to a pedal- operated vehicle comprising a mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention and in particular as described above, in which the aforesaid two thrust levers 11, 12 are pedal cranks and the relative thrust appendages 13, 14 are pedals.

[00105] Preferably, the aforesaid pedal-operated vehicle is a bicycle.

[00106] Advantageously, the aforesaid pedal-operated vehicle may also be a nautical vehicle, in particular a pedal boat, or a recumbent trike or bike. [00107] In the case in which the force applied to the thrust appendages 13, 14 is applied by the hands of a user, the two thrust levers 11, 12 are hand cranks and the relative thrust appendages 13, 14 are hand grips. In this case the mechanism 1 according to the invention may be applied in various actuating devices, such as double crank winches. The operational and structural advantages mutatis mutandis - are similar to those already set forth with reference to the application to a bicycle.

[00108] In particular, the present invention relates to a handbike comprising a mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention and in particular as described above, in which the aforesaid two thrust levers 11, 12 are hand cranks and the relative thrust appendages 13, 14 are hand grips .

[00109] In particular, the present invention relates to a double crank winch comprising a mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention and in particular as described above, in which the aforesaid two thrust levers 11, 12 are hand cranks and the relative thrust appendages 13, 14 are hand grips.

[00110] The present invention also relates to a pedal crank assembly for pedal-operated vehicles, and in particular for a bicycle, comprising:

[00111] - a thrust lever 11, 12, suitable to be associated, at a first end portion 11' to a rotation pin so as to be rotationally integral with said pin during a rotation movement around the axis of rotation XI of the pin; and

[00112] - a pedal 13, 14 associated with the thrust lever at a second end portion 11" of the thrust lever, opposite the first.

[00113] In particular, the pedal 13, 14 is rotatably associated with the second end portion 11 " of the thrust lever 11, 12.

[00114] According to a first aspect of the invention, the aforesaid thrust lever 11, 12 is variable in length so that during said rotation movement of the thrust lever 11, 12 around the aforesaid rotation pin the arm B, offered by the thrust lever and defined by the distance between the pedal 13, 14 and the rotation axis XI, can vary.

[00115] According to a further aspect of the invention, the aforesaid pedal crank assembly comprises a kinematic guide element suitable to guide the movement of variation in length of the thrust lever 11, 12.

[00116] The aforesaid kinematic guide element consists of an elongated body 111 suitable to be associated at a first end portion 111¹ to said rotation pin in a rotationally neutral manner around the axis of rotation XI of said rotation pin 2.

[00117] The elongated body 111 bears at a second end portion 111" thereof, opposite the first, a rotating support body 112, rotatably associated to the elongated body 111 at the second end portion 111" to rotate around a second axis X2 parallel to the axis of rotation XI of the common pin 2.

[00118] The pedal 13, 14 is rigidly fixed to the rotating support body 112 of the kinematic guide element in a radially eccentric position with respect to the second axis X2. This way, the pedal 13, 14 associates kinematically in rotation the kinematic guide element to the thrust lever 11, 12 by means of the aforesaid rotating support body 112.

[00119] Advantageously, the pedal crank assembly for a pedal-operated vehicle, and in particular for a bicycle, according to the invention is a component of the mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention and in particular as described above.

[00120] Advantageously, the pedal crank assembly for a pedal-operated vehicle, and in particular for a bicycle, can be considered as a separate element and be used to perform a retrofitting of an existing mechanism of the traditional type, replacing the traditional fixed-arm pedal cranks.

[00121] The pedal crank assembly according to the invention may be of a simple type without a toothed crown or may comprise a toothed crown P associated to the thrust lever 11, 12 at the first end portion 11'. Preferably, as illustrated in the appended figures, the toothed crown P may be associated to a support body 15 by means of which the thrust lever and the kinematic guide element can be associated to the rotation pin 2.

[00122] The invention permits numerous advantages to be achieved, in part already described.

[00123] The mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention is operationally reliable and simple to construct .

[00124] In fact, in use the useful thrust arm varies automatically without the need for adjustment, increasing in the thrust phase of the single thrust lever (i.e. when the thrust lever is active in the generation of motion) , and decreasing in the recovery phase of the single thrust lever (i.e. when the thrust lever is not used for the generation of motion) .

[00125] As amply described above, the constructive simplicity of the mechanism 1 according to the invention is linked to the fact that compared to similar traditional mechanisms it entails: - realising the thrust lever as a variable-length element; and - coupling to each thrust lever, a kinematic guide element provided at its free end with a rotating support body which is connected eccentrically to the thrust lever by means of the thrust appendage. Such kinematic guide element has the function of guiding the elongation and the shortening of the thrust lever imposing a circular cyclicity related to the rotation of the rotating support body. The realization of such a system does not involve particular constructional or assembly difficulties.

[00126] The operational reliability of the mechanism 1 is related to the fact that the mechanism does not require any adjustment system and to the fact that it allows the application of the external thrust force on a point that moves along a circular or substantially circular trajectory. In other words, the mechanism 1 according to the invention does not affect the method of application of the external force, resulting from this point of view equivalent to traditional mechanisms.

[00127] The mechanism according to the invention finds a particularly preferred application as a mechanism generating movement for bicycles, in substitution of the traditional mechanisms with fixed arm pedal cranks. More specifically, the mechanism according to the invention allows the cyclist to better exploit the thrust impressed during the active rotation phase of each pedal, without however interfering with the regularity of pedalling.

[00128] The invention thus conceived thereby achieves the intended objectives.

[00129] Obviously, its practical embodiments may assume forms and configurations different from those described while remaining within the sphere of protection of the invention.

[00130] Moreover, all the details can be replaced by technically equivalent elements and the dimensions, forms and materials used may be any as needed.

Claims

1. A mechanism for generating a rotation movement with double thrust lever having variable arm, comprising two thrust levers (11, 12), each of which is associated at a first end portion (ll¹) to a common rotation pin (2) around which said rotation movement develops so as to be rotationally integral with said pin (2) with respect to the rotation axis (XI) of the pin and bears at a second end portion thereof (11"), opposite the first, a thrust appendage (13, 14) which is hinged to the thrust lever and destined to receive an external force suitable to determine the rotation movement of the lever (11, 12), wherein said two thrust levers (11 ,12) are fixed to two opposite ends of said common rotation pin (2) to extend in length, orthogonally to the rotation axis (XI) of the pin (2), in diametrically opposite positions with respect to the rotation axis (XI) , the complete rotation movement of each thrust lever being divided into two phases, each corresponding to about one half revolution, of which a thrust phase, in which the thrust lever is active in generating the movement, and a recovery phase, in which the thrust lever is passively dragged in rotation by the movement of the other thrust lever in phase opposition, characterised in that each thrust lever (11, 12) has a variable length so that during the rotation movement of the thrust lever (11, 12) around the common rotation pin (2) the arm (B) , defined by the distance between the thrust appendage (13, 14) and the rotation axis (XI), can vary, and in that said mechanism comprises, coupled to each thrust lever (11, 12), a kinematic guide element suitable to guide the movement of variation in length of the coupled thrust lever (11, 12), wherein each kinematic guide element consists of an elongated body (111) which is associated at a first end portion (111¹) to said common rotation pin (2) in a rotationally neutral manner around the axis of rotation (XI) and which bears at a second end portion (111") thereof, opposite the first, a rotating support body (112; 212), rotatably associated to the elongated body (111) at the second end portion (111") to rotate around a second axis (X2) parallel to the axis of rotation (XI) of the common pin (2) ,

wherein the thrust appendage (13, 14) of each thrust lever (11, 12) is rigidly fixed to the rotating support body (112; 212) of the respective kinematic guide element in a radially eccentric position with respect to the second axis (X2) so as to associate kinematically the kinematic guide element to the respective thrust lever (11, 12) by means of said rotating support body (112; 212),

wherein during the rotation of the thrust lever (11, 12) around the pin (2) - thanks to the rotation of the rotating support body (111) and the positioning eccentricity (E) of the thrust appendage (13, 14) with respect to the second axis (X2) - the thrust appendage (13, 14) performs a complete circular motion eccentric with respect to the rotation axis (XI) of the pin (2), the centre (0) of which is radially shifted toward the arc of circumference corresponding to the thrust half-revolution alternately dragging in axial lengthening and in axial shortening the respective thrust lever (11, 12), so that in the thrust phase upon the varying of the angular position around the rotating support body (112; 212) the arm (B) of the thrust lever (11, 12) progressively increases up to a maximum value equal to the sum of the eccentricity (E) with the distance (D) between the second axis (X2) and the rotation axis (XI) , while in the recovery phase upon the varying of the angular position the arm of the thrust lever (11,12) progressively decreases to a minimum value equal to the distance (D) between the second axis (X2) and the rotation axis (XI) of the pin (2) less the eccentricity (E) .

2. Mechanism according to claim 1, wherein each thrust lever (11, 12) is variable in length thanks to the fact of having an extensible telescopic structure which extends axially along the longitudinal axis of said lever.

3. Mechanism according to claim 1, wherein each thrust lever (11, 12) is axially rigid and is variable in length thanks to the fact of being slidingly associated to said rotation pin (2) or to the respective thrust appendage (13, 14) parallel to the longitudinal extension axis of said lever, the sliding stroke of the thrust lever with respect to the rotation pin (2) or to the respective thrust appendage (13, 14) determining the variation in length of the arm (B) of said thrust lever.

4. Mechanism according to one or more of the preceding claims, wherein said thrust lever (11, 12) is associated to said rotation pin (2) through a support base (15).

5. Mechanism according to claims 3 and 4, wherein said thrust lever (11, 12) is slidingly associated to said rotation pin (2) by means of said support base (15) .

6. Mechanism according to claim 4, wherein said thrust lever (11, 12) is rigidly fixed to said rotation pin (2) by means of said support base (15).

7. Mechanism according to one or more of the preceding claims, wherein each thrust lever (11, 12) is defined by two rods (16, 17) which are parallel to the longitudinal extension axis of the thrust lever (11, 12) .

8. Mechanism according to claim 6, wherein said two rods (16, 17) are connected to each other at the first end (11') of the thrust lever by means of said support base (15) and at the second end (11") of the thrust lever by means of a fork body (18), which the respective thrust appendage (13,14) is rotatably hinged to.

9. Mechanism according to claim 7, wherein said two rods (16, 17) are slidingly associated to said support base (15) .

10. Mechanism according to claim 7, wherein said two rods (16, 17) are slidingly associated to said fork body (18).

11. Mechanism according to one or more of the preceding claims, wherein the rotation plane of each thrust lever (11, 12) is parallel to the rotation plane of the respective kinematic guide element.

12. Mechanism according to claim 11, wherein the rotation plane of each thrust lever (11, 12) is orthogonal to the axis of rotation (XI) of the pin (2) .

13. Mechanism according to claim 11 or 12 wherein each thrust appendage (13, 14) engages the rotating support body (112; 212) of the respective kinematic guide element in a direction parallel to the axis of rotation (XI) of the pin (2 ) .

14. Mechanism according to one or more of the preceding claims, wherein said rotating support body (112; 212) is associated to the elongated body (111) by anti-friction means ( 113 ; 213 ) .

15. Mechanism according to one or more of the preceding claim, wherein said rotating support body (111) is in one piece with the respective thrust appendage (13, 14).

16. Mechanism according to one or more of the preceding claims, wherein the elongated body of the kinematic guide element is constituted by a rod (111) provided at its own second end portion (111") with a circular ring (114) and wherein the rotating support body is constituted by an annular flange (112) which is rotatably inserted inside the circular ring made at the second end portion (111") of said rod (111) in order to rotate around said second axis (X2), the thrust appendage (13, 14) being rigidly fixed to said annular flange (112) in a radially eccentric position with respect to said second axis (X2) .

17. Mechanism according to one or more of the claims from 1 to 15, wherein said elongated body is constituted by a rod (111) and wherein said rotating support body is constituted by an extension (212) which is rotatably associated to said rod (111) in correspondence of said second end (111") of such elongated body (111) in order to rotate around said second axis (X2), the thrust appendage (13, 14) being rigidly fixed to said extension (212) in a distanced position with respect to the second axis (X2) .

18. Mechanism according to one or more of the preceding claims, comprising transmission means of the rotation movement generated by said two thrust levers (11, 12).

19. Mechanism according to claim 18, wherein said transmission means of the movement are kinematically associated directly to the rotation pin (2) or to one of the two thrust levers (11, 12).

20. Mechanism according to one or more of the preceding claims, wherein said two thrust levers (11, 12) are pedal cranks and said thrust appendages (13, 14) are pedals.

21. Mechanism according to one or more of the claims from 1 to 19, wherein said two thrust levers (11, 12) are hand cranks and said thrust appendages (13, 14) are hand grips.

22. Pedal-operated vehicle characterised in that it comprises a mechanism for generating a rotation movement with double thrust lever having variable arm according to one or more of the claims from 1 to 20, wherein said two thrust levers (11, 12) are pedal cranks and said thrust appendages (13, 14) are pedals.

23. Pedal-operated vehicle according to claim 22, characterized in that it is a bicycle.

24. Pedal-operated vehicle according to claim 22, characterized in that it is a nautical vehicle, preferably a pedal boat.

25. Handbike characterised in that it comprises a mechanism for generating a rotation movement with double thrust lever having variable arm according to one or more of the claims from 1 to 20, wherein said two thrust levers (11, 12) are hand cranks and said thrust appendages (13, 14) are hand grips.

26. Double winch crank characterised in that it comprises a mechanism for generating a rotation movement with double thrust lever having variable arm according to the claim 21, wherein said two thrust levers (11, 12) are hand cranks and said thrust appendages (13, 14) are hand grips.

27. Pedal crank assembly for pedal-operated vehicles, and in particular for a bicycle, comprising:

- a thrust lever (11, 12), suitable to be associated, at a first end portion (11') to a rotation pin so as to be rotationally integral with said pin during a rotation movement around the axis of rotation (XI) of the pin; and

- a pedal (13, 14) associated with the thrust lever at a second end portion (11") of the thrust lever, opposite the first,

characterised in that said thrust lever (11, 12) is variable in length so that during said rotation movement of the thrust lever (11, 12) around said rotation pin the arm (B) , defined by the distance between the pedal (13, 14) and the rotation axis (XI), can vary.

and in that said pedal crank assembly comprises a kinematic guide element suitable to guide the movement of variation in length of the thrust lever (11, 12), wherein said kinematic guide element consists of an elongated body (111) which is suitable to be associated at a first end portion (111¹) to said rotation pin in a rotationally neutral manner around the axis of rotation (XI) and which bears at a second end portion (111") thereof, opposite the first, a rotating support body (112; 212), rotatably associated to the elongated body (111) at the second end portion

(111") to rotate around a second axis (X2) parallel to the axis of rotation (XI) of the common pin (2), wherein the pedal (13, 14) is rigidly fixed to the rotating support body (112; 212) of the respective kinematic guide element in a radially eccentric position with respect to the second axis (X2) so as to associate kinematically the kinematic guide element to the respective thrust lever (11, 12) by means of said rotating support body (112; 212).

28. A pedal crank assembly according to claim 27, comprising a toothed crown associated to the thrust lever

(11, 12) at the first end portion (11')·