BACKGROUND OF THE INVENTION

The present invention relates to a mechanical continuous speed variable with gears. BACKGROUND OF INVENTION

Are knowns some variators which allow to vary in a continuous way the speed of rotation of a shaft or a gear in output relative to the speed of rotation of an input shaft in which the two shafts are, between them, parallel and eventually offset. Such variators include a system of gears solar-pinions, which has the solar keyed to one of the two shafts. During the rotation of the sun, the sprockets geared with it are describing an eccentric trajectory relative to the other shaft and alternately one of the sprockets remains still relative to solar and can transmit or receive from an other element, keyed to the other shaft, the motion. EP285719A describes an continuous variator in which the gear system solar-pinions (sprockets) has the solar centrally keyed to a first shaft, while the element keyed to a second shaft presents radial grooves between them inclined at 120°. This variator include, further: a disc, rotatably mounted to the second shaft and parallel to the plate; a cam that touch the disc and that protrudes from it. Each of the three sprockets provided are mounted to a respective shaft tilted 90° relative to that of the solar (and therefore to the first shaft), geared with the sun through a conical coupling and is maintained geared by a relative arm hinged to the first shaft. On each shaft of the sprockets is mounted a geared wheel, mounted to a distal end of the sprocket. Each arm, in correspondence of the geared wheel, has a distal end head slidably inserted in one of the grooves of the plate to contact the disc and/or the cam. Each head comprises a plurality of balls that during the relative rotation between the cam and the plate, periodically contact the cam, in order to lock the corresponding geared wheel and its sprocket relative to solar. Each sprocket, alternatively, remains still relative to the solar and is responsible for the transfer of motion from one shaft to another. The adjustment of the transmission ratio is performed by rotating the cam relative to the second shaft.

US5516132 describe a gear unit for bicycles, in which the solar has an inside geared wheel which engages with a plurality of sprockets; external geared to engage with the chain of the bicycle and a first central hole to engage with a circular disc which on his turn cause a second circular hole disposed eccentrically relative to the center of the disc. In this second hole is housed, with possibility of rotation, a further circular disk keyed eccentrically to a rotation shaft movable through the pedals of the bicycle. To this shaft is integrally mounted a ring from which grow radially a plurality of arcuate elastic elements, each of which carries a clutched sprocket, which rotates in one direction, and keeps it geared with the teeth of the internal solar. Since in order to vary the transmission ratio the first disc is rotated, to maintain the sprockets engaged with the solar gear, the arcuate elements must be deformable, also in virtue of the different angular speeds of the sprockets, the arcuate elements must provide recesses for accommodating a part of the sprockets when are close together between them.

The variators in agreement with EP285719A and US5516132 have a particularly complicated structure. Furthermore, the solar EP285719A, is subjected to continuous stresses from the sprocket locked, and this affects the shaft to which is keyed. In addition, by virtue of its particular shape, the variator according EP285719A involves a fluctuating trend of the torque impressed to the output shaft, in function of the angle of rotation of this shaft. This is especially happen even when the variation ratio is 1 :1. The variator according US5516132 submit the arcuate elements to continuous elastic deformations; also the positioning of the sprocket locked is influenced by the elasticity of those elements. In addition such a variator is used only as a reduction gear for bicycles, since to be able to operate as a multiplier, it would need to first means for transmitting motion from the pedals to the crown of the second means for transferring the movement of the axis to the hub of the rear wheel of the bicycle. This would result in an overlap between the first and second means and interference between the shafts in the input and output.

SUMMARY OF THE INVENTION The purpose of the present invention is to eliminate the above mentioned drawbacks related to the variators of the known type. In particular, the invention seeks to achieve an efficient variator especially as a multiplier, which minimizes the consumption of energy necessary for the motion transfer and allows to control and adjust the output rotation speed to manage in a simple and rapid way any need to variation, for the same input shaft speed.

A further objective is to propose a variator that is easily adjustable and easily assembled, which to be compose by simple and low cost elements in relation to the functions provided.

Constitutes, moreover, one purpose of the invention to provide a variator usable as a multiplier in bicycles, cars, motorcycles, agricultural equipment, ships, without requiring particular and complicated modifications of them, and that it is also applicable in the mechanical industry and for expand the range of work of any motor whatever if is electric, endothermic or wind turbines, water or steam generators, etc...

The above mentioned objectives are achieved with a variator in accordance with the independent claim.

Advantageous technical-functional aspects can be deduced from the dependent claims.

BRIEF DESCRIPTION OF THE FIGURES

Figs. 1 and 2 are perspective views, realized according to opposite directions, of a first realization form of the variator according to the invention;

Fig 3 is a perspective view, in exploded view, of some components of the variator of Fig 1 ;

Figs. 4-5 are views, respectively in horizontal and vertical section of the variator of Fig 1 along planes passing through the axis of the input shaft;

Figs. 6-7, 9-10 and 12-13 are pairs of views, respectively according to the plane A-A and B-B of Fig.4 of the variator of Fig.1 in various positions of regulation and Figs.8, 11 and 14 schematically illustrate the functioning of further components of this variator in the said positions;

Figs. 15 and 16 represent the trend of the torque as a function of the angle of rotation of the output shaft to the variator; Fig 17 is a perspective view of a further realization of the variator proposed: Fig 18 is a perspective view of a detail of Figure 17;

Figs. 19, 20 illustrate vertical sectional view of the variator of Fig. 17 in many operating arrangements; Figs. 21 , 22, 23 the view of the section H-H of Fig. 19 corresponding operating disposal;

Figs. 21A, 22A, 23A schematically illustrate the position and the path of some components as shown respectively in Figs. 21 , 22, 23.

DESCRIPTION OF PREFERRED FORMS OF REALIZATION According to a first form of realization, the variator 100 of speed mechanical continuous according to the invention comprises a frame 13 and at least a first' multiplier group 50. The first multiplier group 50 comprises:

- a drive shaft 1 and a driven shaft 9 whose axis is parallel to the axis of the drive shaft 1 , with only one of said driving shaft 1 and the driven shaft 9 is rotatably mounted to the frame 13: in the illustrated example the drive shaft 1 is rotatably mounted to the frame 13;

- a gear (or sprocket) 2 keyed onto the drive shaft 1 ;

- at least two sprockets 5 (in the illustrated example, four sprockets) geared with the gear wheel 2, a pin 4 for each sprocket 5; a freewheel mechanism 3 coaxially interposed between each pin 4 and its corresponding sprocket 5;

- support means 6 rotatably mounted the driving shaft 1 to support the pins 4 of sprocket 5 at a fixed distance by the driving shaft 1 , with each pin 4 of sprocket 5 rigidly coupled to said support means 6 to maintain the relative sprocket 5 geared to the gear 2 with their axes of rotation parallel to one another; - a thrust element 20 for each sprocket 5, with the thrust element 20 mounted at a first end of the pin 4 of sprocket 5; - a motion transfer element 7, keyed on the driven shaft 9, said transfer element 7 comprising a guide 42 associated with a corresponding pin 4 of sprocket 5, said guides being arranged radially relative to the driven shaft 9 to defining, between two consecutive guides, an angle equal to 360° divided by the number of sprockets 5, with each thrust element 20 slidably inserted into the corresponding guide 42, for, when the relative pin 4 is rigidly coupled to the relative sprocket 5, put in rotation the transfer element 7 and consequently the driven shaft 9;

- translation means, coupled to the frame 13 and comprising a relative movable portion 32, relative to the frame 13, to said movable portion 32 is rotatably mounted to the shaft 1 , 9, drive or driven, which is not coupled to the frame 13, for, changing the arrangement of the movable portion 32 relative to the frame 13, to vary the relative distance between the axes of the driving shaft and the driven shaft 9 and, consequently, the speed ratio r of multiplication of the multiplier group 50;

- adjustment means 34 coupled to the translation means, to adjust the position of the movable portion 32 of the translation means and then to adjust the said distance.

The freewheel mechanism 3 is interposed between the sprocket 5 and the relative pin 4 to make the sprocket 5 rigidly coupled to the respective pin 4 when the angular speed (relative to the axis 71 of the pin 4) of the sprocket 5, dragged by the gear 2, tends to be greater than the angular speed of the pin 4 of the sprocket 5 relative to said axis 71 ; and to allow the free rotation of the sprocket 5 relative to the respective pin 4 when the angular speed of the sprocket 5, relative to axis 71 , when is less than the angular speed of said pin 4, relative to relative axis 71. Since each pin 4 is rigidly coupled to the support means 6, each pin 4 is immobile relative to its axis 71 and the relative angular speed, relative to the axis 71 , is equal to zero. So the relative sprocket 5, when it is in free rotation relative to the its pin 4, must rotate relative to the axis 71 in the opposite direction than the rotation of the drive shaft 1 and the gear 2, to obtain an angular speed, relative to axis 71 , smaller than that of the pin 4. At the same time, the sprocket 5 locked is the one that has the smaller angular speed relative to the axis 70 of the driven shaft 9, since it is the one which is located at the shorter distance from the axis 70 of the driven shaft 9.

In the illustrated form of realization the pin 4 and the support means provide a relative thread 73 (Fig.5 and 19) and the pin 4 is screwed to supporting means 6, but may be provided other fixing solutions to fix the pin 4 to support means.

Preferably, as illustrated in the form of realization referred to Figs. 1-16, the thrust element comprises a slide 20. Each slide 20 is inserted in a corresponding guide 42 with the possibility of sliding in said guide 42 overcoming to a certain frictional force between the guide 42 and the slide 20. In this case, the multiplier group 50 further comprises: a first arm 22 rotatably mounted to the slide 20, for example by the interposition of a bearing 21 , in correspondence of a first hinge axis 40 parallel to the drive shaft 1 ; a second arm 25 rigidly coupled to the first end of the pin 4 of the sprocket 5 and rotatably mounted to the first arm 22 in correspondence of a second hinge axis 41 parallel to the drive shaft 1 , and elastic means 24 functionally interposed between the first and the second arm 22, 25. The elastic reaction of the elastic means 24 is directed to coincide the first hinge axis 40 with the axis 71 of said pin 4, with said elastic reaction having a lower value than said friction force for, when the slide 20 put in rotation the transfer element 7, to keep the first hinge axis 40 (and thus the slide 20) at a distance D1 (see Figure 11), relative to the axis of driven shaft 9, substantially constant and close to that distance in wherein the first hinge axis 40 (and thus the slide 20) is located when the freewheel mechanism 3 makes the sprocket 5 is rigidly coupled to the respective pin 4. This distance D1 is greater than the distance D2, relative of the axis 70 of the driven shaft 9, that will have the axis 71 of the pin 4 relative of the corresponding sprocket 5. In this way will maximize and uniform the torque movement M _T imprinted by the slide 20 to the transfer element 7, see Fig.16 in which is shown the trend of the torque imprinted alternately by slides 20 for transmission ratios r =1 :1 , r =2:1 (multiplication) in case which are provided: the slide 20, the two arms 22, 25 and the elastic element 24 (indicated by "+K") and in case they are not provided (indicated with "- K").

As can be observed in case where r = 1 :1 in the presence of the trend with or without slide 20, arms 22, 25 and elastic element 24 does not change (indicated by "±K"). Similarly, the figure 15 shows the trend of the torque M _T when the variator 100 is used as the reduction gearbox, that is when the drive shaft is the shaft 9 (or 30 if provided) and the driven shaft is the shaft 1.

Are therefore particularly preferred that the variators which comprise a gearing system of geared wheel (sprockets), in which the geared wheel is keyed to one of the two shafts, drive or driven, and wherein during rotation of the geared wheel, the sprockets which it geared to them describes a trajectory eccentric relative to the other shaft, drive or driven, and alternatively each of the sprockets remains immobile relative to the geared wheel, and can transmit or receive motion by a relative element of thrust acting on a transfer element 7, keyed to said other shaft, with such a thrust element, interposed between the sprocket and the transfer element, and comprising the slide, the two arms 22, 25 and the elastic element 24.

According to an alternative form of realization, the thrust element comprises a roller 8 for each sprocket 5, with each roller 8 rotatably mounted to the respective pin 4 of the sprocket 5 with an relative end inserted in a corresponding guide 42 with the possibility of sliding and rotate in said guide 42.

Preferably, as illustrated in figs 1-14, in the variator 100, the multiplier group 50 further comprises: a first gear wheel 72 keyed on the shaft 1 , 9, drive or driven, which is not coupled to the frame 13. In this case, the translation means includes: a transmission shaft 30 rotatably mounted to the frame 13 and disposed parallel to the drive shaft 1 , a second gear wheel 31 keyed on the transmission shaft 30, and gearing the gear wheel 72; a joining movable element 32 having: a first end hinged to the transmission shaft 30, an intermediate portion rotatably mounted to the shaft 1 , 9, drive or driven, which is not coupled to the frame 13, and a second end to which are attached the adjustment means 34, on which it is possible to act in order to tilt the same joining movable element 32 relative to the transmission shaft 30 by varying, in this way, the relative distance between the axes of the drive shaft 1 and the driven shaft 9. This solution allows, when is present only a first multiplier group to have both input shaft 1 and output shaft 30 of the variator 100 rotatably mounted to the frame 13.

Emerge preferred variators according to the invention, in which the drive shaft 1 is rotatably mounted to the frame 13, and the driven shaft 9 is rotatably mounted by the movable portion 32 of the translation means. If the input shaft is 9 then the variator acts as a reduction gear.

According to a preferred form of realization (Figs. 17-23), the variator 100 includes a second multiplier group 60 having an input shaft, driving, constituted by the said driven shaft 9 of the first multiplier group 50 and an output shaft 12, driven, rotatably mounted to the frame 13 with its axis parallel to the input shaft 9, an further gear 2', keyed to the input shaft 9; at least two further sprockets 5' geared with the further gear 2' (in the example shown the further sprockets are four) for each further sprocket 5' is provided a corresponding further pin 4' of the sprocket 5' and an further freewheel mechanism 3' coaxially interposed between the further pin 4' and the corresponding further sprocket 5'; further supporting means 6', rotatably mounted to the input shaft 9 to the second multiplier group 60, to support the further pins 4' of sprocket 5' at a fixed distance from the input shaft 9, with each pin 4' of each further sprocket 5' rigidly coupled to said support means 6' to maintain the relative further sprocket 5' geared to the further gear 2' with the rotation axes parallel to one another, an further element of thrust 8', for each further sprocket 5', with the further thrust element 8' mounted at a first end of a respective further pin 4' of the sprocket 5, a further motion transfer element 14, keyed to the output shaft 12 at the second multiplier group 60, said further transfer element 14 comprising an further guide 42' for each further sprocket 5', said further guides 42' being arranged radially relative to that output shaft 12 defining, between two of said consecutive guides 42', an angle equal to 360° divided by the number of further sprockets 5', with any each further thrust element 8', slidably inserted in a respective further guide 42' for, when its further pin 4' is rigidly coupled with the its further sprocket 5', for rotating the further transfer element 14 and, consequently, the output shaft 12 to the second multiplier group 60, in which the cited translation means, varying the position of the driven shaft 9 of the first multiplier group 50 varies the relative distance between the axes of the input shaft 9 and output shaft 12 to the second group, and consequently, the speed ratio r of the second multiplier group 60. The further freewheel mechanism 3' acts on the relative further sprocket 5' and pin 4' analogously to what the freewheel mechanism 3 acts on the sprocket 5 and pin 4.

The further thrust element 8', may be identical with the thrust element 8, 20 defined relative to the first multiplier group 50 in particular, as well as the thrust element 20 of the first multiplier group 50, can be constituted by the slide 20.

Preferably are provided at least three sprockets 5 and /or at least three further sprockets 5', in the illustrated example there are four sprockets 5 and four further sprockets 5'.

Advantageously, according to an form of realization not shown, the support means 6 and /or the further support means 6' are constituted by a coaxial disc and rigidly coupled to the gear 2 and /or the further gear 2', with said disk having a circular guide coaxial to the gear 2 to simultaneously receive a second end, respectively, of each pin 4 of the sprocket 5 and /or any further pin 4' of the sprocket 5', in which case the gear 2 and /or the further gear 2' is internally toothed for gearing, respectively, with the sprockets 5 and /or with the further sprockets 5'.

As illustrated (Figs. 1-14 and 17-24), the gear 2 and /or the further gear 2' is toothed for externally gearing, respectively, with the sprockets 5 and /or the further sprockets 5'. Furthermore, the support means 6 and /or the further support means 6' may include at least one rigid support element 6, 6' (for example a bracket 6) for each sprocket 5, each support element 6, 6' being, relative to a first end rotatably mounted to the driving shaft 1 and a relative second end rigidly coupled to a pin 4 of sprocket 5 or to a further pin 4' of the sprocket 5' to maintain the relative sprocket geared 5 or the further sprocket 5' respectively to the gear 2 or the further gear 2' with their axes of rotation parallel one to each other.

Emerge advantageous the continuous speed gears for bicycle and for motor vehicles, comprising a mechanical continuous speed variator 100 in accordance with the invention. Even a bicycle and a motorized vehicle comprising a mechanical continuous speed variator 100 according to the invention are particularly preferred.

Are also particularly preferred mechanical equipment, comprising a first and a second internal or external device producing mechanical work, with said first system connected to the driving shaft 1 of the variator 100 described, which realize a continuous variation of speed of any system internal or external connected to the output driven shaft 30, 12 of the variator 100 described. In particular, are preferred motor vehicles, machinery, especially drills and milling machine, turbines and power generators comprising: a mechanical continuous speed variator 100 according to the invention a first device and a second device capable to produce mechanical work, in which said first device is connected to the drive shaft 1 of the variator 100, and said second device is connected to the driven shaft 30, 12 in output to the variator 100 to allow a continuous variation of speed of the second device.

The variator 100 is unidirectional, so it works only if the input shaft 1 receives the rotary motion in the required sense, otherwise the drive shaft 1 spinning freely because of freewheel mechanisms 3. The same applies if it is used as reducer gear. In this case, in the form of realization to a multiplier group (referred to fig 1- 16) the input shaft will be the shaft 9 (or alternatively the shaft 30, when provided), while in the form of realization of in two stages referred to figs. 17-23, the input shaft will be the shaft 12. The proposed variator 100 works as a variable multiplier where a first multiplication is done with the first group 50 and a second multiplication is implemented by the second group 60. In this case, with the same ratio for each group, it get a double final multiplication. When the axis of the drive shaft 1 is aligned with the axis 70 of the driven shaft 9, the ratio is 1 :1. Instead at the maximum distance of translation Ts of the carriage 10 provides the greatest final ratio.

When the carriage 10 is moved and the input shaft 1 starts the rotation, and consequently also the driving gear wheel 2, the movement is transferred to the sprockets 5 which are permanently geared with the driving gear 2. The freewheel mechanisms 3 allow the locking, relative to the gear 2, of the sprocket 5, 5' to the respective pin that geometrically draw the smaller radius and lower angular speed relative to the axis 70 of rotation of the driven shaft 9, 12 and consequently the rotational motion will be transferred to the transfer elements 7, 14.

The remaining sprockets 5 continue to turn freely around the driving gear 2, because, relative to the sprocket locked, runs on major radius and have greater angular speed, relative to the axis 70 of the driven shaft 9, and so they are pushed by the rollers 8 guided by the relative guides 42 of the transfer element 7. So the sprockets 5 do not transmit the rotary motion while roll around of axis 71 of the pin 4, but only when they remain blocked respect to the relative axis. In any way, with the rotation of the rollers 8 guided by the guides 42 of the transfer element 7, one after another the sprockets 5 that describe variable radius, relative to the center of the transfer element 7 to which are associated, are participating in the transfer of the rotation. The exchange point between the sprockets 5, when one ends the phase of engagement and another follow sprockets 5 begins its phase of engagement, is in the moment in which the axis that joins the centers of rotation of these sprockets 5 relative to the center of transfer element 77 becomes perpendicular to the plane of translation TS as in Figs 22 and 22A.

The radius at the exchange point of the sprockets 5 is not equal to the minimum radius Rout (figs. 21 A, 22A and 23A), then the variator 100 makes a slight variation of the radius of engagement during operation at a distance of translation TS constant. The radius described by the sprocket 5 relative to the transfer member 7 varies, starting from a larger radius at the point of exchange, see Fig 22 and Fig 22A, and a decrease until the minimum point then rise again, see Fig 21 and 21A. However the variations are very small, depending on the dimensional choices of components, and do not affect in a radical way in the functioning of the variator 100. Similarly, for the second multiplier gear group 60 of the variator 100, the transfer element 7, keyed on the mobile shaft 9, transmits the rotation to the further gear 2' and consequently to its further sprockets 5'.

One after the other the further sprockets 5', which describe variable radius, participate in the transfer of the rotation to the further transfer element 14 and the output shaft 12, with the help of the mechanisms to freewheel 3'.

A particular case in the geometry of the mechanism, is when the axis of the drive shaft 1 coincides to the axis 70 of the mobile shaft 9, when all the sprockets 5 and further sprockets 5' are involved in the transfer of rotary motion, and transmission ratio is 1 :1. A greater number of sprockets 5 geared with the gear 2 allows an exchange more frequently between the sprockets, maintaining the radius at the time of the exchange almost equal to that obtained on the minimum level of translation TS.

The variator 100, object of the present invention, manages to drive the rollers 8, 8' so as to describe a smaller radius Rout, relative to the center of the transfer element 7 and the further transfer element 14, relative to the constant radius Rin, having its origin on the axis of the shafts 1 and 9, respectively, as exemplified in figs. 21-23.

To calculate the final report, we use the known formulas Ί1 = n1 / n2, where i1 is the ratio of the first multiplier group 50 of the variator 100 and i2 = n2 / n3, where i2 is the ratio of the second part of the variator 100. It is represented with n1 the number of revolutions of the shaft 1 , with n2 represent the number of revolutions of the shaft 9, and with n3 is represented the number of revolutions of the shaft 12. So the final report can be calculated with the formula if = i1* i2.

The formula write above can be rewritten in the following way: i1 = R2 / R1 , and i2 = R3 / R2. Where R2 is the radius between the first group 50 and second group 60 of the variator 100, and R3 is the radius between the second part of the variator 100 and the output shaft. Since both the radius R2 that the radius R3, obtained in the transfer phase of the motion, they are slightly variable, to calculate the value very close to reality it can make the average between the radius at the point of exchange Rsc and the minimum radius Rmin as exemplified in Figs. 22-22A.

It is also preferred a mechanical continuous variator gear 100 consisting of two multiplier groups 50, 60 arranged in series if = i'. i", included within a frame 13, a known elements such as input shaft 1 , an output shaft 12, gears 2, 2' and sprockets (satellites) 5, 5' driven by planetary support means 6, 6' and connected to them by the pins 4, 4' of the sprocket 5, 5' in which transfer elements 7, 14, which serve as the driven wheels, in case of the preferred form of realization illustrated, with four sprockets, and have four guides 42, angularly equidistant, within which slides the rollers 8 mounted to the front ends of the pins 4, 4' that allow, during adjustment, the sprockets 5, 5' to reposition themselves, by varying the radius of trajectory. Furthermore, the sprockets 5, 5' are mounted on the pins 4, 4' with the use of freewheel mechanisms 3, 3' that allow, in the adjustment phase, the remaining sprockets to rotate freely in the opposite direction, when in sequence only the sprocket immobile relative to the gear 2, 2' that runs along the smaller radius relative to the transfer element 7, 14, transmits the motion to the transfer element. According to a preferred form of realization of the above mechanical continuous gear variator 100 has the first multiplier group 50 which presents the driving shaft 1 which carries the gear 2 rotatably mounted to the frame 13 and the transfer element 7 mounted on the carriage 10, mobile on the rails 11 , rigidly coupled to the intermediate shaft 9. Furthermore, in the mechanical continuous gear variator 100 the second multiplier group 60 is driven by the intermediate shaft 9, which is rotatably mounted to the carriage 10, while the output shaft 12, keyed on the element transfer 14, is rotatably mounted to the frame 13 .

Preferably, in this mechanical continuous gear variator 100, the speed control is achieved by implementing a translation TS on the carriage 10, with consequent of double disalignment of the shaft 9 relative to the drive shaft 1 and the driven shaft 12: which is a consequence of the particular kinematics chain that is the basis of operation of the variator with two groups 50, 60.