FR3115085A1 - Transmission with shaft and clutch linked by thread - Google Patents

Abstract

The invention is a very simple and very rustic stepped mechanical transmission, comprising several elementary transmissions each providing a different transmission ratio. It comprises a sliding dog clutch which slides along the input shaft or the output shaft to engage one of the elementary transmissions. The mechanical connection between the sliding dog and the shaft along which it slides is a screw-nut system, which has the effect that the position of the sliding dog depends on the torque to which the transmission is subjected, which is thus an automatic transmission whose transmission ratio varies according to the torque to which it is subjected. Abstract Figure: Fig. 2

Description

Transmission with shaft and dog clutch linked by thread

The invention is an automatic mechanical transmission which is very simple and rustic in design, does not need to be disengaged in order to be able to change gears, does not require synchro either, and which adapts in real time to the torque to which it is subjected to adopt the best transmission ratio.

Technical problem

Many engineers have designed automatic gearboxes, but they have not found a simple way for them to adapt to torque in real time.

A very large number of documents are known describing manual and automatic gearboxes and in particular the following documents.
- GB758516 (A) dated October 3, 1956 by Thomas Hindmarch, which describes a transmission whose input shaft drives pinions engaging with a pinion on the output shaft, at least one pinion on the input shaft input being provided with a speed-selective friction clutch and at least one pinion on the output shaft being provided with a freewheel,
- GB2193766 (A) of February 17, 1988 by Eric Albert Whateley, which describes a transmission comprising two friction clutches and two freewheels, and control means for disengaging one of the friction clutches,
- WO2014171722A1 of April 16, 2014 to Calacana, which describes an input engagement clutch and an output engagement clutch comprising nuts capable of movement in the axial direction by being engaged with an input screw shaft and an output screw shaft rotatably arranged in an input shaft and an output shaft,
- WO2008142219 of November 27, 2008 by Guy Cavalerie [FR] and WO2012156613A1 of November 22, 2012 by Guy Cavalerie [FR] and David Roumeas [FR] which describe gear change devices whose gears are engaged by pawls,
- WO2019191308A1 of October 3, 2019 by Jason Smith [US] et Al. which describes a bicycle transmission by a horizontal shaft which drives circular gears rotating around the axis of rotation of the rear wheel,
- and WO2019175480 A1 of March 6, 2019 and patent application FR2000853 of January 29, 2020 by Franck Guigan [FR] which describe transmissions whose torque ratio varies according to the torque to which they are subjected.

The invention will be well understood, and other aims, advantages and characteristics thereof will appear more clearly on reading the description which follows, which is illustrated by FIGS. 1 to 32 which all represent devices or part of devices according to the invention.

To simplify the exposition,
- it will be said below that an elementary transmission is "connected" or "engaged" when the input shaft of the transmission according to the invention is mechanically linked in rotation to its input and that its output is mechanically linked in rotation with the output shaft of the transmission according to the invention, and that it is "disconnected" or "disengaged" when at least one of these two mechanical connections is not made,
- we will call “adjacent” elementary transmission an elementary transmission whose main plane – that comprising its input or its output, such as a pinion or a drive roller, a crank, a connecting rod or a motor lever – is closest to that of the elementary transmission considered,
- and an elementary transmission will be defined by its "rank" in the list of elementary transmissions whose transmission ratio increases, starting from the elementary transmission of rank 1 for that corresponding to the lowest transmission ratio also commonly called the " first gear”. Several adjacent elementary transmissions of increasing rank can thus be referred to as the “first speed”, the “second speed”, the “third speed”, etc.

is a perspective view of the output shaft 3 and of its central part which is the screw shaft 31 cooperating by threading with the sliding dog clutch 40.

is a perspective view of the output shaft 3 fitted with its sliding dog 40, the lug 42 of which can be rotated by the stop 502 of the output pinion 302.

is a perspective view of a sliding dog clutch 40 provided with movable lugs, which can cooperate with the stops 501 and following of the elementary transmission pinions only when they are in the rest position as is the case here for the lugs 41 41C 42 and 42C, but which can be retracted as is the case here for the lugs 41A and 41B 22.

is a perspective view of three pinions 301 302 and 303 each comprising stops which can be driven in rotation by the sliding clutch, or cause the latter to rotate.

is a perspective view of an improved sliding dog clutch, two lugs of which are provided with rollers 4010 and 4010a, which can be offset along the axis of rotation of the output shaft with respect to a central rest position.

is a perspective view of a parallel-shaft transmission according to the invention, which is provided with a notching means 4002 for moving the sliding dog, cooperating with a wheel 4001 integral with the sliding dog 40.

is a perspective view of a version similar to that shown in the previous figure, but whose movement of the sliding dog 40 can be forced manually along the axis of rotation of the output shaft 3, using of a 3000 fork.

is a perspective view of a transmission according to the invention in an embodiment with 8 forward speeds and two reverse speeds. The pinion driven by the input shaft drives in rotation three satellites 252a 252b which are stepped and correspond to one of the so-called even speeds and the other to the odd speeds, and 252c which corresponds to the two reverse gears. The sprockets 252b7 and 252a8 thus correspond respectively to the 7th and 8th gears.

is a perspective view of a detail of this transmission which shows that one of the two springs determining with the resisting torque the position of the sliding dog are one a spring 4015 connected to the sliding dog by a cable, and the other a compression spring 4016 which is only compressed during reverse or forward engine braking.

is a perspective view of a stepped transmission according to the invention in a space-saving mode of implementation, the two elementary transmissions of which each consist of one of the following two transmission modes of an epicyclic gear train, the first of these modes being the transmission in direct drive from the input shaft 2 to the output shaft 3, the crown 300 rotating in the motor direction with the sun 202 and the satellites 252a 252b and following, this rotational movement being permitted by the clutch freewheel 602, the second being the transmission via the planetary gear train, the movement being transmitted successively from the sun 202 secured to the input shaft 2 to the satellites 252a 252b and following and to the planet carrier 263, the crown 300 remaining fixed.

is a perspective view of the output shaft 3 of the transmission of Figure 10, which includes the screw shaft 31.

is a perspective view of the output shaft 3 of the transmission of FIG. 10, provided with the sliding dog 40 which cooperates with the screw shaft 31 by moving along the axis of rotation of the output 3 when it rotates with respect to this output shaft 3, and which comprises lugs 41 42 and 43 which can rotate either by the torque supplied by the stops 501a and following fixed to the input shaft 2, or by the torque supplied by the stops 502a, 502b and following integral with the planet carrier 263

is a perspective view of the transmission of figure 10, when this sliding dog is rotating by the torque provided by the stops 501a and following fixed to the input shaft 2 to the lugs 41 and following of the sliding dog 40.

is a perspective view of the transmission of FIG. 10, when this sliding dog is rotating by the torque supplied by the stops 502a, 502b and following fixed to the planet carrier 263 to the lugs 41 and 42 and following of the sliding dog. We see the main spring 803 which pushes the sliding clutch towards the plane in which the stops integral with the input shaft are located.

is a perspective view of a similar transmission whose crown has been replaced by a second sun 300, the satellites 252 and 252a each having two adjoining pinions of different diameters, integral with each other.

is a perspective view of a transmission similar to that shown in Figures 10 to 14, the crown of which is integral with a wheel 8.

as well as the following two are perspective views which illustrate a variant of the transmission of FIGS. 10 to 14, which can operate both in forward gear and in reverse gear. The sliding dog clutch in this case comprises secondary lugs 41A 42A et seq. We distinguish the guide 6002 from the lug of the sliding dog of the direction of rotation of the freewheel 602.

is a perspective view of the same transmission, in direct forward gear.

is a perspective view of the same transmission, this time in reverse and with resistance from the output shaft which caused the sliding dog to move along the axis of rotation of the engine away from the engine to that it cooperates with the planet carrier of the planetary gear train.

as well as the following three are perspective views of details of a two-way freewheel that allows the crown to rotate forwards. We distinguish the lug 6001 of the sliding dog clutch in the direction of rotation 6000, the crown 300 which includes a lug 3021 which is here locked in rotation by the pawl 6003.

is a perspective view of the same freewheel, but which here allows the crown to rotate only in reverse because the motor rotates in reverse, the pin 3021 being blocked in the opposite direction of rotation by the pawl 6004 .

is a perspective view of this freewheel with motor.

is a perspective view of this freewheel with the motor rotating in the opposite direction to that in which it rotates in Figure 22.

is a perspective view of a transmission according to the invention which allows a strong reduction. The input shaft 2 drives the input pinion 202 which cooperates directly with the output pinion 302 with a transmission ratio equal to 1/4. The input shaft 2 also drives the ring gear 401 of the intermediate shaft 400, with a transmission ratio equal to 1/3 which is integral in rotation with the input pinion 201 which cooperates directly with the output pinion 301 with a transmission ratio equal to 1/8. The transmission ratio of the first gear is thus 1/4 and that of the second gear 1/24.

is a perspective view of the transmission of figure 24 seen from another angle, which allows to see the freewheel 602 located between the ring gear 602 of the intermediate shaft and the input pinion 201, freewheel which allows the pinion first speed output gear 301 to rotate as fast as second speed output gear 302, as well as sliding dog 40 and main spring 803.

is a perspective view of the same transmission comprising only part of the components so that one can distinguish the input shaft 2 and the output shaft 3 with its screw shaft 31.

is a perspective view of the transmission of Figure 26 seen from another angle.

as well as the following are perspective views of a transmission according to the invention in an embodiment with parallel shafts, comprising three elementary transmissions 2001 2002 and 2003 each composed of two pinions, an input pinion driven by the shaft input 2 and an output pinion capable of driving the output shaft 3. The elementary transmission 2001 is composed of input pinions 201 and output 301, the elementary transmission 2002 is composed of input pinions 202 and output 302, and the elementary transmission 2003 is made up of input 203 and output 303 gears.

is a perspective view of this transmission stripped of its output gears so that one can see the sliding clutch 40 which is a nut cooperating with the part of the output shaft 3 which is the screw shaft 31. Two so-called main springs elastically maintain this sliding dog clutch in the same plane as the planes of rotation of the input pinion 202 and of the output pinion 302.

is a perspective view of a transmission part according to the invention in a particular embodiment. The input shaft 2 comprises a pinion rotating four satellites 252a 252b 252c and 252d.

is a perspective view of this complete transmission, provided with its four satellites each comprising a series of pinions integral with each other, each series of pinions being driven by a freewheel by one of the planets 252a 252b 252c and 252d. Each of these pinions rotates a sun fixed to a ring comprising abutments capable of driving the lugs of the sliding dog clutch. A distinction is made between sets of series of so-called even pinions 252a2 and 252a4 and series of odd satellites 252b1 and 252b3, which respectively drive the so-called even elementary transmissions and so-called odd elementary transmissions. Thus, when the sliding clutch 40 simultaneously connects two adjacent elementary transmissions, this does not cause conflict.

is a perspective view of a transmission according to the invention comprising three elementary transmissions composed of one of the circular teeth 301 302 and 303 which are integral in rotation with the output shaft 3 and located in a plane perpendicular to its axis of rotation, the screw-shaft here being the input shaft 2. The teeth are represented in a simplified way, but those skilled in the art can obviously use conical teeth.

All these figures illustrate arrangements chosen to enable the different methods envisaged to be clearly explained. Those skilled in the art can advantageously produce more compact versions, in particular for versions whose input and output shafts are aligned. It is in fact possible not to combine the length of the three sets which are the main spring 803, the zone of movement of the sliding clutch 40, and all the toothed pinions. These three series of elements can indeed be located in concentric cylindrical volumes that do not overlap.

All the figures represent toothed pinions with symmetrical teeth, but those skilled in the art will advantageously use toothed pinions with asymmetrical teeth for the gears always turning in the same direction. The teeth of these asymmetrical gears have a part cooperating with another pinion which forms a greater angle with the circumference of the pinion than the opposite part. It is in fact known that such gears offer a better ratio [torque transmitted/weight] and better efficiency in this particular case.

The present invention is a mechanical transmission of movement from an input shaft 2 to an output shaft 3, called stepped transmission, comprising a plurality of means for transferring the movement of said input shaft to said output shaft, called elementary transmissions - 2001, 2002 and where appropriate following - each having an input pinion - 201, 202 and where appropriate following - rotatable by said input shaft and an output pinion - 301, 302 and the case any following - capable of driving the said output shaft in rotation,
- at least two elementary transmissions capable of ensuring this motion transfer according to different transmission ratios or opposite directions of rotation,
- the stepped transmission being provided with at least one rotating clutch means called sliding dog clutch 40 able to move with respect to said elementary transmissions along an axis parallel to a shaft 31 called screw shaft integral in rotation with said input shaft or said output shaft, and rotating one of said elementary transmissions or being driven by it,
characterized in that said screw-shaft and said sliding dog cooperate with each other by threading, the torque to which the sliding dog is subjected screwing it in one direction, and a return means 803 called the main spring screwing it in the opposite direction.

Detailed description of the invention

The principle of the present invention consists in measuring the torque to which a transmission shaft is subjected by a screw-nut device of which one of the two elements, the screw and the nut, moves along the shaft considered as a function of two forces, on the one hand the torque to which the screw-nut device is subjected which moves it in a direction parallel to the axis of rotation of the shaft in question, and on the other hand a return means, for example elastic opposite.

Depending on the direction of the screw pitch of the screw shaft 31, it is therefore possible to obtain both a reduction and an increase in the torque ratio when the resistive torque increases or decreases. The applications are different, one of the two options is mainly intended to transmit the movement of a motor to a wheel while the other mainly concerns the recovery of energy during deceleration and braking.

By convention, the shaft-screw shaft is designated above and below and the nut is designated by sliding dog, but it could quite be the opposite, the sliding dog being able to be provided with a screw cooperating with a nut integral with the shaft in question.

Input pinion and output pinion also designate the input and output of an elementary transmission respectively, but it can be any mechanical coupling such as for example a pulley driving a belt or a roller, without leaving the scope of the present invention.

In the following description, a freewheel is placed on an input pinion or on an output pinion, but the reverse arrangements to those described also work. Similarly, the sliding dog 40 is shown as driving the output shaft, but it can also be driven by the input shaft. More generally, it is possible to invert input shaft and output shaft in the solutions described without departing from the scope of the invention, which provides different effects having different applications.

The sliding dog can move along the output shaft or the input shaft, inside at least one pinion of an elementary transmission, and can thus cooperate with at least three different elementary transmissions .

A transmission according to the invention may comprise two elementary transmissions each provided with a freewheel of opposite direction, as illustrated by FIGS. 6 and 7. This transmission with parallel shafts comprises two forward gear ratios and two reverse gear ratios which change automatically depending on the direction in which the input shaft 2 rotates and the resistance to rotation of the output shaft 3.

The input shaft 2 is fixedly connected to the pinion 202, which is the gear pinion whose transmission ratio is the highest since it is the largest input pinion and it rotates the output pinion 302 which is the smallest. It always spins at the speed of the input gear.

The other two input sprockets are smaller and each connected to input shaft 2 by a freewheel, but these two freewheels are in opposite directions. If the motor rotates in one direction, the pinions 201 and 202 rotate in its direction of rotation, while if it rotates in the other direction, it is the pinions 202 and 203 that rotate in its direction of rotation. The presence of these freewheels has the consequence not only that the pinions 201 and 203 are driven in rotation only in the direction in which the motor rotates, but also that they can rotate faster than the pinion 202.

Each of the output gears 301 302 and 303 is driven by the input gear which is in the same plane, the output gear 301 by the input gear 201, the output gear 302 by the input gear 202 and the output pinion 303 by the input pinion 203. They drive the output shaft 3 by a sliding clutch 40 which is a nut cooperating with the output shaft which comprises a part 31 forming a thread. The sliding dog clutch is held elastically in the plane of the pinions 202 and 302 by one or two so-called main springs. The rest position of the sliding dog is that in which it is driven by the output pinion 302.

Those skilled in the art have at their disposal many means for the lugs of the sliding dog to cooperate effectively with the stops of a pinion of an elementary transmission, in particular to prevent the surface of cooperation between these elements being too weak.

He can play on the shape of the cooperation surfaces between these two elements so that they facilitate the centering of these cooperation surfaces with respect to each other.

A sliding dog clutch is advantageously provided with lugs each provided with a wheel 4010 which can rotate around an axis perpendicular to the axis of rotation of the sliding dog dog, and cooperate with a stop whose shape is such that it can embed there. This means of making the sliding dog position coincide with one of those in which it best cooperates with an elementary transmission is illustrated in FIGS. 4 and 5. The stops 501 502 and following of the output pinions 301 or 302 or 303 have which are pointed, and the lugs of the sliding dog clutch 40 are each provided with a wheel, respectively 4010 and 4010a, which cooperate with these stops.

Figure 5 shows an improvement which is that the sliding dog may comprise two parts, one called the central part (4014) comprising the lugs with which it cooperates with the elementary transmissions, and the other comprising the thread by which it cooperates with the screw shaft, and these two parts can advantageously move away from each other along the axis of rotation of said sliding dog, being returned to a rest position by an elastic return (4015 and 4016) . When the sliding dog is not in the plane where it cooperates best with a pinion, these springs deform and allow the useful part 4014 of the sliding dog to shift laterally so that a lug 4010 is located in the plane in which it cooperates best with the stop 501 of the nearest pinion.

When the axis of rotation of a caster is located in a plane comprising the pointed end of a stop of an output pinion of a first intermediate transmission, the caster considered actually connects this elementary transmission, but when this roller also encounters the pointed end of the abutment of the output pinion of an adjacent elementary transmission, it ceases to be in balance and the sliding dog 40 shifts laterally along the axis of rotation of the output to drive in rotation only the first intermediate transmission.

It is also possible to provide the lugs and the stops with magnets so that the lugs are preferably placed in the plane in which they cooperate best with the stops 501 502 and following.

An equivalent solution consists in allowing all the elementary transmissions to move slightly in relation to the sliding dog clutch. The aforementioned documents WO2008142219, WO2012156613A1 and WO2019191308A1 also propose centering means.

It is essential that a single elementary transmission effectively transmits the rotational movement of the input shaft to the output shaft, to avoid conflicting teeth.

A known means consists in providing the transmission with a one-way clutch, called freewheel 601 allowing the output of an elementary transmission to rotate at the same speed as that of another elementary transmission which is connected simultaneously and rotates faster or slower.

The sliding dog clutch can comprise several lugs 41 and 41A, 42 and 42B which are retractable, as illustrated in figure 3. It is a spring which brings them out from inside the central part of the sliding dog dog when possible. , but the lugs retract under the effect of the thrust of a stop in a direction of the opposite direction to that allowing their cooperation with a stop. This also allows an elementary transmission to have an integrated freewheel function, and to facilitate the return to first gear when the engine torque decreases.

Conflicts of teeth can also be avoided by using an electromagnetic clutch, the sliding dog having instead of lugs 40 41 and following magnets or electromagnets cooperating with magnets or electromagnets located on the elementary transmissions instead of position of stops

When the transmitted torque is close to the disengagement condition of an elementary transmission, the staged transmission could engage and disengage an elementary transmission at a rapid alternating rate, which is not desirable because it would cause jerks in the transmission and premature wear. To avoid this, it is desirable that the torque driving the clutch of an elementary transmission be different from that driving the disengagement of the elementary transmission which is adjacent to it, so that there is a range of torques between these two values. , in which no elementary transmission change occurs.

The change of position of the sliding dog can be limited by a notching means (4002) favoring the positions of the sliding dog in which it can only connect a single elementary transmission or preventing it from leaving such a position.

Such a notching means 4002 is represented in FIG. 6. It pivots around an axis 4003 and can be elastically brought closer to the ball bearing 4001 to favor the positions of the sliding dog clutch in which it can only connect a single elementary transmission .

This notching means can also be pressed firmly against the ball bearing 4001 to prevent any change in transmission ratio.

A transmission according to the invention can also be provided with a means making it possible to move by force, manually or by a motor, the position of the sliding clutch, to force the stepped transmission to use a determined elementary transmission. Such a means is represented in FIG. 7, which shows a transmission according to the invention devoid of its output pinions, so that one can see the sliding dog clutch driving the output shaft 3 in rotation, this sliding dog dog being able to slide using the 3000 fork along the output shaft to select the output pinion which should drive it in rotation. The sliding dog can then connect different elementary transmissions having different characteristics, such as different forward or reverse transmission ratios, a neutral position and one or more variable-ratio elementary transmissions that can serve as a clutch, for example.

A transmission according to the invention can be provided with a so-called sensitivity adjustment means making it possible to vary the stiffness of said main spring, which has the effect of varying the values of the torque driving the engagement and disengagement of the elementary transmissions , as well as the rest position of the sliding dog when the transmission is not subjected to any torque. This setting allows you to choose between leisurely or more sporty driving, but it also allows you to change the transmission ratio voluntarily.

A simple way is to move the bearing surface of the end of the main spring opposite to that pushing the sliding dog. By moving this support surface, the hardness of the spring is modified during operation.

Figures 8 and 9 show a preferred version of a transmission with eight forward speeds and two reverse speeds. One of the two springs holding the sliding dog clutch in the eighth forward gear position is not, as in the other figures, a compression spring, but a 4015 spring connected to the sliding dog clutch by a cable, and therefore operating under tension. This cable can slide in a sheath, which makes it possible to deport the adjustment control close to the hand or foot of the user of a bicycle, for example, who can thus easily modify the driving mode from "outing" to " sport” for example, but also change gears by a voluntary action by pulling more or less on the cable.

For a bicycle or any other system with acyclic motorization, it is possible to place on the path of the cable a damping means (not shown) so that the sliding dog does not move during a cycle, but only in function of the average value of the resistive torque over several cycles.

Changes in the resistance of the main spring and/or the rest position of the sliding dog can be obtained by taking into account the speed of rotation of the input or output shaft, as well as the value of the torque at which is submitted the input tree. The sensitivity adjustment means may comprise a means for measuring the speed of rotation of the input shaft or of the output shaft. This speed measuring means can be used to move the bearing surface of the end of the main spring, so that an increase in the speed of rotation of the output shaft favors the use of gear ratios higher, and/or that below a certain rotational speed the transmission automatically reverts to first gear. The movement of the support surface can be obtained by motorized means if the speed measurement means is electronic, but also by a simple ball regulator whose spacing of the balls mechanically modifies the position of this support surface.

A means of measuring the torque supplied by the motor, that is to say the torque to which the input shaft is subjected, can also be used to move the bearing surface of the end of the main spring, from such that an increase in the torque undergone by the input shaft promotes the use of higher gear ratios, and/or that below a certain torque value the transmission automatically switches back to first gear. The displacement of the support surface can be obtained by motorized means if the torque measuring means is electronic, but also by a screw-nut device of which one of the two elements, the screw and the nut, moves along the input shaft as a function of two forces, on the one hand the torque to which the screw-nut device is subjected which moves a control means in a direction parallel to the axis of rotation of the shaft d input, and on the other hand a return means, for example elastic in the opposite direction. It is almost the same thing as the device for changing the transmission ratio, except that the control means considered comprises lugs cooperating with input pinions integral in rotation running over the entire length of the pinions of entry of elementary transmissions.

The fork 3000 described in FIG. 7 can also be used to force the transmission to adopt a lower transmission ratio, even at first gear, either manually or motorized.

The shape of the elements of cooperation between the sliding dog and the toothed pinion which it drives or by which it is driven can advantageously be designed by those skilled in the art so that the movement of the sliding dog resulting in a change of transmission elementary is easier in one direction than in another.

To easily change the transmission to first gear, while the rest position of the sliding dog is in many cases that corresponding to the last speed, it is advantageous that the shape of the elements of cooperation between the sliding dog and the toothed pinion qu it drives or by which it is driven either such that, when the torque to which the transmission is subjected is negative, the pressure of the abutment 502 of the pinion on the lug 42 of the sliding dog causes a displacement of the sliding dog in the corresponding direction connecting an elementary transmission with a lower torque ratio. Those skilled in the art can easily design such cooperation elements so that the pressure of one on the other gives rise to a component pushing the sliding dog in the direction of the elementary transmission corresponding to the first gear.

A freewheel placed between the engine and the input shaft allows the sliding dog to be brought back into first gear without having to run the engine in reverse.

In the case where the engine torque is unstable during a cycle, as for example when it comes to the crankset of a bicycle or an internal combustion engine, it is advantageous that the change in position of the sliding dog along the screw shaft is slowed down by a damping means (not shown). The damping is advantageously stronger in one direction than in the other, to facilitate the return to first gear.

The pitch of the thread by which the screw shaft and the sliding jaw cooperate in rotation can also be chosen so that a momentary drop in the engine torque during a cycle does not allow an elementary transmission change. In the case of a drive of the input shaft by a crank, there are two acyclisms per revolution, and it is advantageous that the screw pitch of the screw shaft - and that of the sliding dog which is the same – i.e. less than half the displacement of the sliding dog necessary to disconnect one elementary transmission and connect another.

Those skilled in the art can also use all the known means making it possible to reduce or compensate for the acyclisms, such as for example oval gears.

There are several means which make it possible to avoid shocks during the commissioning of an elementary transmission, and these means can be combined with each other.

A spiral spring 702 can be arranged between two parts of the transmission, for example between the center of the output pinion and its periphery comprising the teeth, as shown in FIG. 2. This means of elastic deformation allows progressive loading of the coupling between the input shaft and the output shaft by the elementary transmission considered during its connection.

Another means of limiting shocks when connecting an elementary transmission consists in providing the stepped transmission with a clutch means allowing progressive loading of the coupling between the input shaft and the shaft. output by the elementary transmission when it is connected. It is for example possible to provide an elementary transmission with a centrifugal clutch, which has the effect that it only drives the output shaft after it has been engaged by the sliding dog clutch. All limited slip means can be considered, including in particular those used for limited slip differentials and transmissions.

Each of the two progressive loading means described above can be located at any location of the transmission, for example on the input shaft, on the output shaft, on an input or output pinion. 'an elementary transmission, or even between the thread and the lugs of the sliding dog.

It is also possible to play on the speed of the engine to adapt its speed of rotation during an elementary transmission change.

At least one of the elementary transmissions may have a variable transmission ratio depending on the speed of rotation of its input or output pinions, and/or depending on the torque to which it is subjected. It is possible to use as elementary transmissions only such continuously variable transmissions without departing from the scope of the present invention.

A continuously variable elementary transmission inserted between elementary transmissions with a fixed transmission ratio can play the role of synchro between them.

The use of a continuously variable transmission allowing a zero transmission ratio as an elementary first gear transmission can play the role of a clutch.

There are many ways to produce such continuously variable transmissions, including those described in the aforementioned documents WO2019175480 and FR2000853.

Figure 16 shows a transmission according to the invention in a particular application, similar to that shown in Figures 10 to 14, the crown of which is integral with a wheel 8 instead of being connected to the frame by a freewheel. This wheel can be immobilized by a brake or released in rotation by the operator, to have the same function as the freewheel previously described. It can also be a flywheel which, when the torque to which the transmission is subjected is less than a predetermined value, rotates at the speed of the input shaft and the output shaft, but is driven in rotation at a different speed and in a direction of rotation which can also be different when the torque exceeds this value. This makes it possible to withstand jerks in the transmission. The flywheel can be braked permanently or on demand by a braking means to then regain the speed of rotation of the input and output shafts when the torque has become lower again. It can also be slowed down by an electric machine, which makes it possible to recover the energy it has stored. This electric machine can also function as an electric motor to supplement the torque supplied by the input shaft 2. Such a device can therefore serve as a braking means and as a SREC (Kinetic Energy Recovery System).

A transmission according to the invention driving a flywheel in rotation is subjected to a torque which decreases as the speed of this flywheel increases, and this leads to the connection of elementary transmissions having transmission ratios higher, which accelerates the rotation of the flywheel which can thus reach very high speeds. It is advantageous to use continuous variable elementary transmissions for this.

The stored energy can then be recovered by driving another transmission according to the invention, connected in series and downstream of the first. The set of two transmissions mounted in series upstream and downstream of a flywheel is an effective torque regulator.

In a simple version allowing the motors in particular to withstand a temporary overload, a transmission according to the invention has its input and output shafts aligned, and comprises two elementary transmissions, one of which is in direct drive.

FIGS. 10 to 23 illustrate a particular implementation, the elementary first-speed transmission comprising an epicyclic train and the second-speed transmission being the direct drive.

The input shaft rotates one of the three components of the planetary gear train. Above and below, the components of a planetary gear set are understood to mean the planet carrier equipped with its satellites, and the two sun gears (sun or crown). The planetary gear may comprise either a planet carrier, a sun and a ring gear, or a planet carrier provided with planet gears themselves comprising two toothed pinions of different diameters integral with each other, associated either with two rings of different diameters, or with two suns of different diameters. These different types of planetary gear sets offer well-known different advantages, in particular as regards the direction of rotation of that of their components constituting the output shaft with respect to the direction of rotation of that constituting their input shaft, and the possibility of have very low or very high or very close to 1 gear ratios.

In the configuration shown, the elementary transmission of the lowest rank transmitting the movement consists of a clutch of the output shaft on the input shaft, directly or by an intermediate transmission means, the crown being able to rotate freely in the motor direction, but not in the opposite direction, because it is mechanically connected to the frame integral with the motor by a freewheel 602. The transmission is then in direct drive, the three components of the planetary gear train rotating together at the same speed of spin. When this first elementary transmission is disconnected, the stepped transmission passes into a configuration in which the elementary transmission transmitting the movement is constituted by the operation of the planetary gear train itself, the three components of which rotate at different speeds, a freewheel preventing the crown to rotate in the opposite direction to the motor direction, so that the input shaft drives the output shaft at a lower rotational speed than that at which it would have been driven in the direct drive configuration described above.

The stepped transmission represented by FIGS. 10 to 23 is provided with a sliding dog clutch on its output shaft 3, and lets the ring gear rotate freely in the motor direction in one of the two possible positions of the sliding dog clutch 40. Thus, the stepped transmission can rotate in direct drive.

An improved version allows the motor to run in both forward and reverse. It is shown in Figures 17 to 23. The sliding clutch is moved both towards the motor and in the opposite direction, depending on the direction of rotation, and the freewheel allows the ring gear to rotate only in the motor direction.

The sliding dog clutch 40 in this case comprises two series of lugs 42 and 42A. We see in Figure 17 that the pin 42A is driven by the abutment 502 of the planet carrier, because the spring is compressed by an excessive resistant torque while the engine is running forward.

It can be seen that when the transmission rotates forward at cruising speed as illustrated by FIG. 18, that is to say when the torque to which it is subjected is below a determined threshold, it is the lug 41 sliding dog which is driven by the stop 501A of the input shaft. This is also the case when reversing, because the compression and tension of the spring would also be almost zero in this case.

In Figure 19, the transmission is in reverse but with excessive resistance from the output shaft. The spring then works in traction, and the sliding dog has therefore moved closer to the motor. Pin 42A is driven in reverse by stop 502 of the planet carrier.

Figures 20 to 23 illustrate one embodiment of a freewheel allowing the crown wheel to rotate only in the direction in which the motor is rotating. It always locks in the opposite direction to that of the motor. This freewheel comprises a ratchet ring 6000 guided by a pin 6001 sliding in a groove 6002, such that this ratchet ring moves along the axis of rotation of the motor either towards the motor when the motor is running. forward, or in the opposite direction when turning in the opposite direction. The pawl ring comprises two pawls 6003 and 6004 of opposite directions, and only one of them cooperates with a stop 3021 integral with the crown 302. It is the pawl 6003 which cooperates with the stop 3021 when the motor is running forward and the pawl 6004 which cooperates with this stop 3021 when the motor is running in reverse.

The transmission shown in Figures 10 to 23 has only two elementary transmissions, but there is nothing to prevent a transmission having a larger number of elementary transmissions from being designed according to the same principle.

When the reduction ratio must be high, a recommended solution to reduce the size and the weight of the transmission consists in having the input shaft drive a so-called second gear output shaft which is parallel to it, via a pinion. cooperating with a pinion secured to this second gear output shaft. The input shaft also drives an intermediate shaft which is parallel to it, via a pinion cooperating with a crown fixed to this intermediate shaft, and this intermediate shaft in turn drives via a pinion a so-called first speed output shaft which is coaxial with the second gear output shaft. Each of the two output shafts has tappets capable of driving the stops of the general output shaft in rotation, as illustrated in figures 24 and 25. To take an example, the pinion of the input shaft drives the output shaft. second gear output by a ratio of 1/4, and the intermediate shaft by a ratio of 1/3, and the intermediate shaft drives the first gear output shaft by a ratio of 1/8. The transmission ratio of the first gear is thus 1/4 and that of the second gear 1/24.

With a transmission with parallel shafts, the input and output shafts can both be fitted with a screw shaft and a sliding dog, provided that these two dogs are mechanically linked to be located in the same plane perpendicular to the axes of rotation of the input and output shafts. The advantage of such an organization is a reduction in friction since only an elementary transmission moves. Only one of these sliding dogs moves along the shaft with which it cooperates according to the variation of the torque to which the shaft considered is subjected. The second only moves because the first has moved. It is therefore necessary to choose whether it is the torque at the input or at the output of the stepped transmission that governs the two joint movements.

In a version making it possible to have a large number of elementary transmissions while limiting the number of freewheels, the input shaft drives a sun itself driving two satellites, each of these two satellites called primary satellites - 252a 252b - being integral in rotation in one direction of rotation only with input gears - 252a2, 252a4 and following for the primary satellite 252a, and 252b1, 252b3 and following for the primary satellite 252b - elementary transmissions whose output gears have a common axis of rotation which is that of said output shaft 3 and cooperate with a single sliding dog 40, and two adjacent elementary transmissions are driven by a different primary satellite.

Figures 30 and 31 show a preferred version of a four-speed transmission, the transmission ratios of which are respectively 0.4 for the first gear, 1 for the second, 3 for the third and 9 for the fourth. The satellite carrier is fixed here. Freewheels are placed between the so-called primary planet wheels driven by the sun of the input shaft, and there are two types of series of pinions: stepped planet wheels comprising so-called even pinions which drive suns of even speeds (the second and fourth) and stepped satellites comprising so-called odd pinions which drive suns of odd speeds (first and third). These stepped satellites are driven by the primary satellites via freewheels, which has the advantage that, when the sliding clutch 40 is in an intermediate position in which it could simultaneously connect two adjacent elementary transmissions, this does not cause conflict. This method makes it possible to produce transmissions according to the invention comprising only two freewheels regardless of the number of forward gears, which can therefore become very high.

The satellite carrier can be equipped with a freewheel allowing it to turn in the opposite direction to the motor direction. In this case, when the motor shaft rotates in the opposite direction, it drives the entire device, which constitutes a reverse gear. However, this only works if none of the transmission ratios of the elementary transmissions is less than 1.

Two stepped satellites are used for even speeds as in figures 30 and 31, but a third satellite, optional, drives by its pinion 252c2 the last gear pinion and a first reverse gear pinion 252c1 which is mechanically connected to it by a wheel free of direction opposite to that of the forward gears. This optional third satellite also provides engine braking.

It is possible to make simplified versions of transmissions according to the present invention. For example, the functions of one-way clutch called free wheel and of clutch means called sliding dog clutch can be obtained by two toothed pinions whose teeth are asymmetrical to obtain the one-way clutch effect, and by an elastic deformation of any part of the elementary transmission considered to obtain the so-called sliding dog clutch means effect. These two toothed pinions do not cooperate in one of the two possible directions of their respective rotations, and by playing on the flexibility of deformation of the toothed pinions, it is possible to favor the connection of an elementary transmission for a range of torque or rotational speed . This version is not shown.

It is also possible to produce double-clutch gearboxes according to the invention. Such a transmission comprises two sets of elementary transmissions corresponding to so-called even and odd transmission ratios as is widely known. Each of these sets of elementary transmissions transmits its movement to a clutch disc. These clutch discs cooperate alternately with the output shaft 3 of the assembly via a third clutch disc. The advantage is to avoid shocks when putting a freewheel into service, since the latter is put into service before ensuring the transmission of the torque to the output shaft 3. This arrangement is therefore particularly suitable for power transmissions.

It is possible to constitute an elementary transmission by assembling in series or in parallel several so-called primary transmissions, and these so-called primary transmissions can be of different natures, connecting and disconnecting according to different parameters such as torque or speed, or according to a combination of two different types of parameters, or manually or on command from a computer.

This makes it possible to engage an elementary transmission according to a combination of manual or computerized commands, and rotational speed and transmitted torque parameters.

The present invention is compatible with those described in the aforementioned document WO2019191308A1, as illustrated in Figure 32.

the present invention is compatible with those described in the aforementioned documents WO2008142219 and WO2012156613A1, the shuttle comprising the pawls described in these documents being moved inside the output shaft not by the cyclist at the handle but by said screw device -nut.

It is particularly advantageous to assemble in series or in parallel stepped transmissions according to the invention with other manual or automatic transmissions of the prior art or according to the invention.

When two elementary transmissions are associated in series, it is advantageous for the axis of rotation of the output shaft of the second elementary transmission to coincide with that of the input shaft of the first elementary transmission.

A transmission according to the invention can be associated with a manual transmission allowing the user to choose an operating mode ranging for example for a bicycle or a "passenger" to "sport" car, while the transmission according to the invention adapts then the transmission ratio to the conditions encountered such as the nature of the terrain for example.

A series assembly of stepped transmissions according to the invention makes it possible to have a number of transmission ratios which is the result of the multiplication of the numbers of elementary transmissions of each of the stepped transmissions.

A series assembly also makes it possible to vary the transmission ratio by taking into account both the torque transmitted by the input shaft and that transmitted to the output shaft. The two transmissions in this case advantageously have opposite operating modes, the increase in the torque of the upstream transmission increasing its transmission ratio while the increase in the torque of the downstream transmission decreases its own. To take the example of a vehicle, the upstream transmission can advantageously select a low transmission ratio when the torque transmitted by the engine is low, while the downstream transmission selects a high transmission ratio when the resistive torque of the wheel is weak.

The transmissions according to the invention can also be assembled in parallel to drive two wheels of the same axle without the need for a differential.

Two transmissions according to the invention or of other natures can be associated in parallel, sharing the same output shaft and having input shafts driven in rotation by different means, such as for example a crankset and a motor in the case of electric bicycles.

When a transmission according to the invention comprises an epicyclic train, one of the components of this train can receive energy from one energy source and the other from another, as is known.

The present invention is also a machine provided with a stepped transmission like those which have just been described, or receiving its energy from such a transmission, or transmitting it to the outside by such a transmission.

The present invention is also a method of changing the transmission ratio of a transmission like those which have just been described, consisting in measuring the torque to which a transmission is subjected by the position of a sliding dog subject on the one hand to the couple screwing it on the input shaft or on the output shaft of the stepped transmission in one direction, and on the other hand to a return means called main spring screwing it in the opposite direction, and to be transmitted by this sliding dog movement from the input shaft to the output shaft via an elementary transmission.

Apps

The main applications are:
- automatic stepped gearboxes with fixed or variable ratios,
- continuously variable transmissions with gears,
- centrifugal clutches without loss of energy,
- torque limiters,
- the transfer of power to a plurality of drive wheels by a plurality of transmissions according to the invention, replacing the differentials,
- the combination of several energy sources,
- electric motors equipped with a transmission according to the invention to withstand any torque greater than that supplied by the motor during its normal operation, for example that which is necessary for starting or in the event of a mechanical overload,
- the recovery of energy during braking, by coupling the wheels to an energy storage means, by varying the transmission ratio to measure the stored energy and therefore the amount of braking,
- the real-time adaptation of the transmission ratio of wind and tidal turbines to the optimal speed of their electric generator,
- energy storage in flywheels of industrial machines and toys,
- the propulsion of bicycles and other vehicles or machines moved by a pedal or cranks,
- winches, jacks and winches whose transmission ratio automatically adapts to the resisting torque,
- rotating tools.

Claims (10)

Mechanical transmission of movement from an input shaft (2) to an output shaft (3), called stepped transmission, comprising a plurality of means for transferring the movement of said input shaft to said output shaft, called elementary transmissions ( 2001, 2002 and where appropriate following) each having an input pinion (201, 202 and where appropriate following) rotatable by said input shaft and an output pinion (301, 302 and where appropriate following) capable of rotating said output shaft,
- at least two elementary transmissions capable of ensuring this motion transfer according to different transmission ratios or opposite directions of rotation,
- the stepped transmission being provided with at least one rotating clutch means called sliding dog (40) able to move relative to said elementary transmissions along an axis parallel to a shaft (31) called screw shaft integral in rotation with said input shaft or said output shaft, and rotating one of said elementary transmissions or being driven by it,
characterized in that said screw-shaft and said sliding dog cooperate with each other by threading, the torque to which the sliding dog is subjected screwing it in one direction, and a return means (803) called the main spring screwing in the opposite direction. Staged mechanical transmission according to Claim 1, characterized in that the sliding dog can move along the output shaft or the input shaft, inside at least one pinion of an elementary transmission. Staged mechanical transmission according to any one of the preceding claims, characterized in that it is provided with a so-called sensitivity adjustment means making it possible to vary the stiffness of the said main spring, which comprises means for measuring the speed of rotation of the said input shaft or said output shaft. Staged mechanical transmission according to any one of the preceding claims, characterized in that it is provided with a so-called sensitivity adjustment means making it possible to vary the stiffness of the said main spring, which comprises means for measuring the torque to which the said input tree. Staged mechanical transmission according to any one of the preceding claims, characterized in that the said input and output shafts are aligned, and that it comprises two elementary transmissions, one of which is in direct drive. Staged mechanical transmission according to any one of the preceding claims, characterized in that the said input and output shafts are parallel and both provided with a screw shaft and a sliding dog, and that these two dogs are linked mechanically to lie in the same plane perpendicular to the axes of rotation of said input and output shafts. Staged mechanical transmission according to any one of the preceding claims, characterized in that the input shaft drives a sun itself driving two satellites, each of these two satellites called primary satellites (252a 252b) being integral in rotation in one direction. of rotation only with input pinions (252a2, 252a4 and following for the primary satellite 252a and 252b1, 252b3 and following for the primary satellite 252b) of elementary transmissions whose output pinions have a common axis of rotation which is that of said output shaft (3) and cooperate with a single sliding dog (40), and that two adjacent elementary transmissions are driven by a different primary satellite. Staged mechanical transmission characterized in that it consists of two mechanical transmissions according to any one of the preceding claims which are assembled in series and which have opposite operating modes, the increase in the torque of the upstream transmission increasing its transmission while increasing the torque of the downstream transmission decreases its own. Machine provided with a stepped mechanical transmission according to any one of the preceding claims or transmitting its power by such a transmission, or set in motion by such a transmission. A method of changing the transmission ratio of a transmission according to any one of the preceding claims, consisting in measuring the torque to which a stepped transmission is subjected by the position of said sliding dog subject on the one hand to the torque screwing it onto said drive shaft. input or on said output shaft of said stepped transmission in one direction, and on the other hand to said main spring screwing it in the opposite direction, and to transmit by said sliding dog the movement of said input shaft to said output shaft by through one of said elementary transmissions.