阅读说明：本技术 动力系 (Power train ) 是由 亚瑟·德拉瓦 于 2019-02-12 设计创作，主要内容包括：本发明涉及一种用于脚踏车辆的动力系(1)。所述动力系(1)包括主输出板(3)和次级输出板(4),该次级输出板经由第一自由轮(16)联接至底部托架(2)。底部托架(2)与主输出板(3)之间的联接通过可变形的传动元件(15)和周转齿轮系进行。(The invention relates to a powertrain (1) for a scooter. The powertrain (1) comprises a primary output plate (3) and a secondary output plate (4) coupled to a bottom bracket (2) via a first freewheel (16). The coupling between the bottom bracket (2) and the main output plate (3) is made by means of a deformable transmission element (15) and an epicyclic gear train.)

1. A powertrain (1) for a scooter vehicle, the powertrain comprising:

-a crankshaft (2) arranged to rotate around a first rotation axis (30),

a main output sprocket cog (3) arranged to drive an output drive chain or belt (23),

a first motor (40),

a second motor (50),

an epicyclic gear comprising a first input element, an output element and a sun gear (5),

the crankshaft (2) and the second motor (50) being connected to the epicyclic gear via the first input element so as to form a first input of the epicyclic gear,

the first motor (40) being connected to the epicyclic gear via the sun gear (5) so as to form a second input of the epicyclic gear,

the output element connecting the epicyclic gear to the primary output sprocket toothed disc (3) so as to form an output of the epicyclic gear,

it is characterized in that the preparation method is characterized in that,

-the main output sprocket toothed disc (3), the first input element, the output element and the sun gear (5) are arranged to rotate around a same second axis of rotation (31) different from the first axis of rotation (30),

-the main output sprocket toothed disc (3) is integral with the output element, and

-the powertrain (1) comprises:

-a secondary output sprocket disc (4) arranged to rotate about the first axis of rotation (30) and to mesh with the output drive chain or belt (23),

a first free wheel (16) arranged to prevent the secondary output sprocket toothed disc (4) from rotating slower than the crankshaft (2) when the crankshaft (2) rotates in a normal pedaling direction,

-a speed-change gear reduction system maintaining a direction of rotation to transmit rotation between the crankshaft (2) and the first input element.

2. The powertrain (1) as claimed in claim 1, wherein the first input element is a ring gear (9) of the epicyclic gear and the output element is a planet carrier (6) of the epicyclic gear.

3. The powertrain (1) according to claim 1, wherein the first input element is a planet carrier (6) of the epicyclic gear and the output element is a ring gear (9) of the epicyclic gear.

4. The powertrain (1) according to any of the preceding claims, wherein the transmission gear reduction system maintaining the rotational direction comprises a deformable transmission element (15), such as a chain or a belt.

5. The powertrain (1) according to any one of the preceding claims, wherein the second motor (50) is connected to the first input element of the epicyclic gear through a single reduction.

6. The powertrain (1) according to any one of the preceding claims, wherein the first motor (40) is integral with the sun gear.

7. The powertrain (1) according to any one of the preceding claims, wherein the first motor (40) and the second motor (50) are located on the same side of the epicyclic gear.

8. A power train (1) according to any of the preceding claims, the power train further comprising:

-an angular position measuring element of the first motor (40),

an angular position measuring element of the second motor (50),

-a current measuring element of the first motor (40),

-a current measuring element of the second motor (50),

-a control unit connected to the first motor (40), the second motor (50) and arranged to control the first motor (40) and the second motor (50) based on an angular position of the first motor (40), an angular position of the second motor (50), a current of the first motor (40) and a current of the second motor (50), the control unit being arranged to control the second motor (50) according to current or torque control and to control the first motor (40) according to angular position or angular velocity control.

9. The powertrain (1) as claimed in the preceding claim, wherein the control unit is arranged to control the first motor further in dependence on a gear ratio parameter.

10. The powertrain (1) according to the preceding claim, wherein the control unit is arranged to determine a rotational speed setpoint and to apply the rotational speed setpoint on the first motor (40), the rotational speed setpoint being determined directly proportional to the rotational speed of the second motor (50) obtained by an angular position measuring element of the second motor (50) and proportional to the gear ratio parameter.

11. The powertrain (1) according to any of claims 8-10, wherein the control unit controls the second motor (50) further based on a gear ratio parameter and an assist level parameter of the powertrain.

12. The powertrain (1) according to the preceding claim, wherein the control unit is arranged to determine a current or torque setpoint and to apply the current or torque setpoint on the second motor (50), the current or torque setpoint being determined directly proportional to the torque or current of the first motor (40) obtained by a current measuring element of the first motor (40) and depending on a gear ratio parameter of the powertrain and an assistance level parameter of the powertrain.

13. The powertrain (1) according to any one of the preceding claims, wherein the crankshaft (2) and the first input element are connected such that the first input element rotates faster than the crankshaft (2).

14. The powertrain (1) according to any one of the preceding claims, wherein the diameter of the primary output sprocket toothed disc (3) is smaller than the diameter of the secondary output sprocket toothed disc (4).

15. The powertrain (1) according to any one of the preceding claims, wherein the second motor (50) is connected to the first input element such that the first input element rotates slower than a rotor of the second motor (50).

16. A power train (1) according to any of the preceding claims, further comprising a second freewheel (17) arranged to prevent the second motor (50) from driving the crank shaft (2) in a rotational direction corresponding to a forward movement of the scooter.

17. A scooter comprising a powertrain (1) according to any one of the preceding claims, a wheel and an output drive chain or belt in mesh with a primary output sprocket toothed disc (3), a secondary output sprocket toothed disc (4) and pinions of the wheel.

Technical Field

The present invention relates to a powertrain for a pedal vehicle, in particular for a bicycle or an electric bicycle.

Background

Document WO2016/034574 describes a bicycle power train consisting of an epicyclic gear, a crankshaft, an output sprocket, a first motor and a second motor. The epicyclic gear consists of a ring gear, a sun gear and a planet carrier.

In this powertrain, the carrier comprises double planet gears, which carrier is complicated and expensive to manufacture, assemble.

Disclosure of Invention

One of the objects of the present invention is to provide a powertrain for a scooter, which is simple to manufacture, light, strong, compact and particularly effective.

To this end, the invention provides a powertrain for a scooter, the powertrain comprising:

a crankshaft arranged to rotate about a first axis of rotation,

a main output sprocket cog arranged to drive an output drive chain or belt,

the first motor is a motor for driving the motor,

the second motor is driven by a second motor,

an epicyclic gear comprising a first input element, an output element and a sun gear,

the crankshaft and the second motor are connected to the epicyclic gear via a first input element so as to form a first input of the epicyclic gear,

the first motor is connected to the epicyclic gear via the sun gear, so as to form a second input of the epicyclic gear,

the output element connects the epicyclic gear to the main output sprocket cog to form the output of the epicyclic gear,

it is characterized in that the preparation method is characterized in that,

the primary output sprocket cog, the first input element, the output element and the sun gear are arranged to rotate about the same second axis of rotation different from the first axis of rotation,

the main output sprocket chainring is integral with the output member, and

-the powertrain comprises:

a secondary output sprocket arranged to rotate about a first axis of rotation and to mesh with an output drive chain or belt,

a first free wheel arranged to prevent the secondary output chainring from rotating slower than the crankshaft when the crankshaft is rotating in the normal pedaling direction,

a speed change gear reduction system that maintains a rotational direction to transmit rotation between the crankshaft and the first input element.

In a powertrain according to the present invention, the rotational axes of the main output sprocket cog, the first input element, the output element and the sun gear are spatially offset from the rotational axis of the crankshaft. This makes the size of the sun gear independent of the diameter of the crankshaft. This then enables the mounting of a sun gear with a smaller diameter and therefore an increase in the ratio of the plus epicyclic gear. Therefore, a sufficient reduction ratio of the epicyclic gear can be obtained without using the double planetary gear. This makes the powertrain easier to manufacture, easier to install, and less expensive.

The powertrain according to the invention also enables a high reduction ratio between the first motor and the output sprocket cog. In practice, this reduction ratio depends on the reduction ratio of the epicyclic gear, the reduction gear ratio between the crankshaft and the first input of the epicyclic gear and the ratio of the number of teeth between the secondary output sprocket-toothed disc and the primary output sprocket-toothed disc.

The connection of the primary output sprocket cog to the output member enables the output of the epicyclic gear to drive the primary output sprocket cog without reducing speed. This makes the assembly of the powertrain particularly easy, and makes the powertrain particularly lightweight and compact. In addition, this results in a particularly high efficiency.

A secondary output sprocket, rotating about a different axis than the primary output sprocket, guides the output drive chain or belt around the crankshaft to spread the lower and upper segments of the chain. This therefore ensures that there is sufficient space between the length of drive chain or belt to the rear wheel to pass the rear base of the frame. The rear base is a tube of the frame for connecting the attachment point of the rear wheel to the mounting bracket of the central motor. Preferably, the secondary output chainring is located outside of a housing of the powertrain.

Since the crank shaft is different from the shaft of the first input element, there is a first gear reduction between the crank and the first input element. This reduces the torque in the epicyclic while increasing the rotational speed of the epicyclic. As a result, the robustness requirements of the epicyclic gear are reduced and it is possible to make the epicyclic gear lighter. In addition, faster rotation of the components of the epicyclic gear makes it compatible with smaller motors, which typically rotate faster and with less torque than larger motors.

The first freewheel is designed to allow mechanical power to be transmitted from the crankshaft to the secondary output sprocket. The first free wheel is arranged, preferably directly, between the crankshaft and the secondary output sprocket. In the locked position, the crankshaft directly drives the secondary output sprocket. In the free position, the secondary output sprocket can rotate faster than the crankshaft. This position of the freewheel enables a particularly low first gear ratio of the powertrain.

Additionally, in some cases, the first free wheel enables the crankshaft to directly drive a secondary output sprocket that in turn drives an output drive chain or belt that drives the rear wheel. Thus, all of the pedaling power is directly transmitted to the output drive chain or belt via the secondary output sprocket. The remainder of the transmission system, including the epicyclic gear, is therefore unloaded, allowing high mechanical efficiency. This may occur, for example, if the electrical system of the powertrain is shut down or if power assist is disabled and the lowest gear ratio of the powertrain is selected.

The secondary output chainring may also transmit part of the power if the instantaneous torque on the crank exceeds a certain threshold and the first motor is saturated at its maximum torque. During the duration of this pedal input, the instantaneous value of the powertrain gear ratio decreases, e.g., if the set gear ratio is low, the first freewheel can begin to operate and drive the secondary output sprocket, which then transfers the rider's excess torque to the output drive chain or belt. When this occurs (as may occur when power assist is activated), the output drive chain or belt receives power via the epicyclic gear and the primary output sprocket on the one hand, and via the secondary output sprocket on the other hand. The presence of the secondary output sprocket chainring and the first freewheel prevents the gear ratio of the powertrain from being less than 1.

It should be noted that the powertrain has one mode of operation, which may be referred to as a "normal mode of operation", in which the total power (which is the sum of the power of the two motors and the power of the rider) is supplied to the main output sprocket. The main output sprocket chainring transmits power to the rear wheel via an output drive chain or belt. This mode of operation is the one most commonly used by cyclists using electric bicycles.

In the powertrain according to the invention, there is transmission between the crankshaft and the first input of the epicyclic gear by a speed change gear reduction system which maintains the direction of rotation. The speed change gear reduction system allows for gear reduction of angular velocity, which is of particular interest because the speed of the crank is much lower than the speed of the electric motor.

For the purpose of this document, the normal pedaling direction is the rotational direction of the crankshaft corresponding to the forward motion of the scooter. Due to the coupling in the powertrain, the elements of the powertrain preferably each have a rotational direction corresponding to the normal pedaling direction.

The different characteristics of the powertrain according to the invention allow the elements of the powertrain to have a particularly large mechanical/gear reduction ratio while maintaining a relatively small number of gear stages. Thus, the powertrain provides excellent efficiency while maintaining small size and light weight.

The transmission efficiency is optimized by few transmission stages. Additionally, the small number of transmission stages also reduces transmission clearances between elements of the powertrain, which may improve control accuracy of the powertrain. In particular, this control accuracy is particularly useful if the first motor is speed-controlled based on the speed of the second motor.

An advantage of the powertrain is that it allows a gear reduction to be interposed between the crankshaft and the first input member of the epicyclic gear. This means that all elements of the epicyclic gear rotate faster and with less torque. This reduces the mechanical stress on these components.

Another advantage of the powertrain according to the present invention is that it provides a continuously variable transmission ratio.

Preferably, the primary and secondary output sprocket chainrings directly or indirectly engage a drive chain or belt that drives the rear wheels of the scooter. However, any other mechanism for driving the output drive chain or belt is possible within the scope of the invention.

Preferably, the powertrain comprises a control unit for controlling the first motor and the second motor.

The fact that the crankshaft and the secondary output sprocket have the same axis of rotation means that the crankshaft is not on the path of the output drive chain or belt connecting the primary output sprocket to the rear wheel.

Preferably, the first and second axes of rotation are parallel. Preferably, the axis of rotation of the second motor is also parallel to the first and second axes of rotation.

For the purposes of this document, two connected or joined elements may be directly or indirectly connected or joined. The two connected or joined elements may be directly or indirectly engaged, for example, via at least one intermediate gear, belt, and/or roller.

For the purposes of this document, the terms "input" and "output" are understood to mean both an input and an output in a power train. The input is preferably a mechanical power input and the output is preferably a mechanical power output.

For the purpose of this document, the ratio of the epicyclic gear is the reduction ratio of the epicyclic gear. In the case of an epicyclic gear with a single planet gear, this ratio is the ratio of the diameter of the annulus gear to the diameter of the sun gear. The ratio of the epicyclic gearing is preferably here between five and ten.

For the purpose of this document, the pedalling vehicle may be, for example, a bicycle, a moped, a tricycle.

For the purposes of this document, "gear ratio of the powertrain" is defined as the ratio between the speed of the secondary output sprocket and the speed of the crankshaft. It may also be referred to as a "gear ratio parameter". The gear ratio parameter is a parameter that can be manually controlled by the rider via the control interface or automatically calculated by the control unit based on other parameters.

For the purposes of this document, an element "arranged to rotate about an axis of rotation" is preferably an element that is substantially symmetrical about that axis.

For the purposes of this document, "fixed ratio" between two objects means that their rotational speeds are a constant ratio.

For the purposes of this document, "level of assistance of the powertrain" refers to a portion of the power imparted by the electrically powered auxiliary device relative to the power imparted by the rider. It can be calculated as the combined power of the two motors divided by the sum of the combined power of the two motors and the power of the rider. Which may also be referred to as an "assistance level parameter". The assistance level parameter is a parameter that can be manually controlled by the rider via the control interface or automatically calculated by the control unit based on other parameters.

For the purposes of this document, angular position measurement is equal to angular velocity measurement. Indeed, the powertrain according to the invention preferably comprises means for determining the angular speed of one of the motors depending on the angular position of the motor.

For the purposes of this document, the current measurement is equal to the torque measurement. Indeed, the powertrain according to the invention preferably comprises means for determining the torque of one of the motors from the current supplied to that motor.

The epicyclic gear includes a ring gear, a carrier and a sun gear. The planet carrier comprises planet gears. The sun gear may also be referred to as the inner sun gear or the sun gear. The ring gear may also be referred to as an outer sun gear. The sun gear and the ring gear are preferably connected via satellite gears.

Preferably, the planet carrier comprises only a single planet gear. Indeed, the powertrain according to the present invention avoids the use of double planetary gears.

Preferably, the powertrain comprises one or more batteries.

Preferably, the main output sprocket disc is fixed to a hollow shaft arranged around the axis of the first motor and coaxial with the epicyclic gear.

Preferably, the secondary output sprocket is attached to a hollow shaft disposed around and coaxial with the crankshaft.

The primary output sprocket ring can be referred to as a "first output sprocket ring", and the secondary output sprocket ring can be referred to as a "second output sprocket ring".

The transmission between the crankshaft and the first input member is via a transmission mechanism such that the first input member rotates in the same direction as the crankshaft.

Preferably, the primary and secondary output chainrings are connected to the rear wheels of the scooter via an output drive chain or belt.

The rotation of the crank shaft is caused by the pedaling motion of the rider using the bicycle. The use of an epicyclic gear using the crankshaft as an input allows the gear ratio between the rotation of the crankshaft and the rotation of the primary and secondary output sprocket discs to be varied.

Preferably, the control of the motor is a feedback control, also referred to as a closed loop control.

The powertrain according to the invention may operate as a rear pedal brake that allows recuperation of braking energy to recharge the battery. Preferably, the powertrain is then arranged such that the rear wheels can drive the chain to transfer motion to the main output sprocket chainring. This can be achieved, for example, by mounting the pinion of the rear wheel in a fixed position on the hub of the rear wheel. Thus, if the scooter is descending a slope, the chain spins while driving the main output sprocket cog. This will cause the first motor and/or the crank to rotate in a direction corresponding to the normal pedaling direction. If the rider wants to brake, he can operate the crank backwards, i.e. in the opposite direction to the normal pedaling direction. The position of the crank can be determined by means of an angular position measuring element of the second motor, for example by means of a second sensor. Preferably, then, the second motor is not controlled by the control unit. Preferably, the first motor is torque or current controlled, wherein the negative torque set point corresponds to the fact that the motor acts as a generator. The negative torque set point is preferably proportional to the negative angle formed by the crank. The measured value of this angle is set to zero when the rider operates the crank backwards. Thus, when the rider moves the crank rearward, the first motor begins to brake the bicycle. The rider experiences a torque tending to move the crank forward that is proportional to the braking torque of the first motor. This is therefore a stable system. The more the rider pushes backwards, the more the first motor brakes. If the rider releases the rearward pressure on the crank, the crank will move forward and the first motor will stop braking the bicycle. If the main output sprocket ring is connected to the planet carrier, the planet carrier acts as a differential. Therefore, this tends to rotate the first motor in a direction corresponding to the normal stepping direction. The first motor is then controlled to resemble a generator to brake the bicycle and thus transfer electrical energy to the battery. The system may be activated, for example, by a rear pedal, similar to a torpedo system. The power of the brake and thus the amount of energy supplied to the battery can be controlled according to the rear pedaling force applied by the rider.

In a first embodiment of the invention, the first input element is a ring gear of an epicyclic gear and the output element is a planet carrier of the epicyclic gear.

According to a preferred example of this embodiment, the crankshaft is connected to the ring gear at a fixed ratio; the rotor of the second motor is connected to the ring gear at a fixed ratio; the rotor of the first motor is connected to the sun gear at a fixed ratio; the ring gear forms a first input of an epicyclic gear and the sun gear forms a second input of the epicyclic gear; the planet carrier forms an output part of the epicyclic gear; the planet carrier and the main output chain wheel fluted disc are integrated. More preferably, the rotor of the first motor is integral with the sun gear.

In a second embodiment of the invention, the first input element is the planet carrier of an epicyclic gear and the output element is the ring gear of the epicyclic gear.

According to a preferred example of this embodiment, the crankshaft is connected to the planet carrier at a fixed ratio; the rotor of the second motor is connected to the planet carrier at a fixed ratio; the rotor of the first motor is connected to the sun gear at a fixed ratio; the planet carrier and the sun gear form two input parts of an epicyclic gear; the ring gear forms the output of the epicyclic gear, which is connected to the main output sprocket cog at a fixed ratio. More preferably, the rotor of the first motor is integral with the sun gear.

In an embodiment of the invention, the speed change gear reduction system for maintaining the direction of rotation comprises a deformable transmission element, such as a chain or belt.

For the purpose of this document, the deformable transmission element may be, for example, a flexible belt. The deformable transmission element may be a belt, preferably made of a flexible material and preferably provided with teeth or recesses on its inner surface. The deformable transmission element may also be a chain.

The use of a deformable transmission element also makes it possible to reduce tolerance margins, i.e. play, in the transmission compared to the use of gears.

Preferably, the speed-change gear reduction system which maintains the direction of rotation is a deformable transmission element, a double gear stage or a gear in which one gear has an internal toothing, since in each of these transmission systems the direction of rotation of the input is the same as the direction of rotation of the output.

Unlike a gear drive, a drive by means of a deformable drive element leaves the choice of the center distance between the rotating elements at both ends. This gives much design freedom. It also makes it possible to achieve a large gear reduction ratio between the crankshaft and the first input of the epicyclic gear, without increasing the size of the system. This high gear reduction ratio allows the selection of a relatively small diameter crankshaft, which reduces the weight of the powertrain. This high gear reduction ratio also reduces the size of the electric motor. This increases the gear reduction ratio between the crankshaft and the first input member without increasing the size of the powertrain.

In addition, the use of a deformable transmission element to reduce the speed of the crankshaft to the first input of the epicyclic results in a particularly large distance between the crankshaft and the axis of the epicyclic. This makes it possible to increase the size of the ring gear of the epicyclic gear to increase its ratio. The purpose of increasing the ratio of the epicyclic gear is to increase the speed of the two electric motors and thus reduce the size of these motors. This reduces the weight and volume of the powertrain. In this way, the diameter of the two electric motors can be reduced, allowing the two motors to be positioned on the same side of the powertrain.

The deformable transmission element isolates the crank from vibrations that may be caused by the electric motor or transmission. This dampens the vibrations felt by the rider's foot, thereby improving comfort.

In an embodiment of the invention, the second motor is connected to the first input element of the epicyclic gear via a single reduction. For example, the rotor of the second motor may directly mesh with the first input member. This limits losses and gear backlash.

In one embodiment of the invention, the first motor is integral with the sun gear.

In one embodiment of the invention, the first motor and the second motor are located on the same side of the epicyclic gear. This design makes it possible to reduce the bulk of the powertrain and to facilitate assembly, since the two motors are therefore close to the same electronic board to which they can both be connected. Preferably, the motor is located on an opposite side of the powertrain from the output sprocket cog.

In one embodiment of the invention, the powertrain further comprises:

an angular position measuring element of the first motor,

an angular position measuring element of the second motor,

a current measuring element of the first motor,

the current measuring element of the second motor,

a control unit connected to the first motor, the second motor and arranged to control the first motor and the second motor based on an angular position of the first motor, an angular position of the second motor, a current of the first motor and a current of the second motor, the control unit being arranged to control the second motor according to a current or torque control and to control the first motor according to an angular position or angular velocity control.

In an embodiment of the invention, the first motor functions to control the gear ratio of the powertrain. One of the functions of the first motor is to provide a given transmission ratio. The transmission ratio is the ratio between the angular velocity of the crankshaft and the angular velocity of the secondary output sprocket. For example, the gear ratio may be determined based on a gear ratio parameter provided by a user of the cycle or determined by the control unit to provide an automatic gear change to the rider. Such a determination may be performed in particular by a gear change algorithm. The first motor is preferably controlled in angular position or angular velocity, for example via a control unit controlling the first motor, such that an angular position or angular velocity set point is observed.

In an embodiment of the invention, the second motor functions to manage the appropriate level of assistance for the powertrain. One of the functions of the second motor is to assist the rider in his movement by adding torque to the crank. Preferably, the assistance level is determined by the control unit, in particular based on an assistance level parameter. The assist level parameter may be determined by a user or automatically by a control unit of the powertrain. Preferably, the assist level is independent of the gear ratio of the powertrain. The second motor is preferably controlled in current or torque, e.g. via a control unit controlling the second motor, such that a current or torque set point is met.

Preferably, the control unit is electrically connected to the angular position measuring element of the first motor, the angular position measuring element of the second motor, the current measuring element of the first motor and the current measuring element of the second motor.

It should be noted that there is no fundamental difference between position control and speed control, since there is a direct mathematical relationship between these two values. Angular velocity is the time derivative of the angular position. For example, the motor is controlled to operate at a fixed angular velocity as if the motor were controlled to follow an angular position that varies linearly with time.

For example, in the first embodiment, the control of the first motor and the second motor may be performed in the following manner.

Angular velocity omega of rear wheel of bicycle_RAngular velocity omega with secondary output sprocket tooth disc_platIn proportion:

ω_R＝R_R.ω_plat

wherein R is_RIs the transmission ratio between the angular velocity of the rear wheel of the bicycle and the angular velocity of the secondary output sprocket.

The angular velocity of the secondary output sprocket cog is given by the following equation.

Wherein R is_outIs the ratio of the number of teeth, R, between the secondary output sprocket cog and the primary output sprocket cog_CIs the gear reduction ratio, ω, between the crankshaft and the ring gear_M1Is the angular velocity, ω, of the first motor_pedIs the angular velocity of the crank and R is the ratio of the epicyclic gear.

The crank angular velocity may be based on a measured angular velocity of the second motorIs determined as follows.

Wherein R is_M2Is the reduction ratio between the second motor and the ring gear. R_M2Preferably between 5 and 15.

The control unit uses a gear ratio parameter GC (gear coefficient) and the measured angular speed of the second motorTo determine the angular velocity set point applied to the first motor

Such that the angular velocity of the rear wheel is proportional to the angular velocity of the crank when the GC parameters are fixed. By combining the equations, one can obtain:

and therefore the angular velocity set point imposed on the first motor. In the same way, it is possible to set the speed by assigning a position set point (which is only the speed set point) to the first motor

Integral of) to control the first motor in position.

The equation for the torque of the epicyclic gear is given as follows:

wherein, C_M1Is the torque of the first motor, C_courIs the torque of the ring gear, and C_PSIs the torque of the carrier.

Knowing that the torque of the crank and the torque of the second motor are added at the ring gear, it is possible to rely on the torque C measured on the first motor_M1And the torque C measured on the second motor_M2To calculate the torque C of the crank_ped。

C_ped＝R_c.(C_M1.R-C_M2.R_M2)

Like the powertrain of most pedal vehicles, this eliminates the need for a torque sensor.

It can be taken into account that the assistance level parameter AF (assistance factor) is for example equal to the ratio of the power supplied by the electric motor to the total power supplied to the main output sprocket.

Since it is taken into account that the power is equal to the torque multiplied by the angular velocity, it can be based on the torque C of the first motor_M1The torque of the second motor sufficient to achieve the required assist level parameter is determined by the following equation.

And thus the torque or current set point applied to the second motor.

As mentioned above, the speed control of the first motor is very sensitive to the transmission gap. In practice, the synchronization of the sun gear with the first input of the epicyclic gear is done via a certain multiplication factor proportional to the gear ratio of the powertrain. The instantaneous angular position of the sun gear is known via the angular position sensor of the first motor. The angular position of the first input of the epicyclic gear is derived from the angular position read by the angular position sensor of the second motor. Therefore, it is preferable to limit the transmission clearance between the second motor and the first output of the epicyclic gear. It is therefore preferred to have only one reduction stage between the second motor and the first input of the epicyclic gear in order to reduce the transmission backlash. Similarly, the position of the first input of the epicyclic gear set is affected by the drive gap between the first input and the crankshaft. It should be noted that the use of a deformable transmission element, such as a toothed belt, also greatly reduces the transmission gap.

In an embodiment of the invention, the control unit is arranged to determine a current or torque setpoint and to apply said current or torque setpoint on the second motor, the current or torque setpoint being determined to be directly proportional to the torque or current of the first motor obtained by the current measuring element of the first motor and being dependent on a gear ratio parameter (GC) of the powertrain and an assistance level parameter (AF) of the powertrain.

In an embodiment of the invention, the crankshaft and the first input element are connected such that the first input element rotates faster than the crankshaft. This achieves gear reduction. Because of the low torque, the epicyclic gear is hardly subjected to mechanical stress. In addition, this increases the rotational speed of the elements of the epicyclic gear, which enables the use of electric motors that rotate faster and therefore are smaller in size.

In one embodiment of the present invention, the diameter of the primary output sprocket cog is smaller than the diameter of the secondary output sprocket cog. The diameter of the secondary output sprocket cog can be, for example, 1.5 to 3 times greater than the diameter of the primary output sprocket cog.

In an embodiment of the invention, the second motor is connected to the first input element such that the first input element rotates more slowly than the rotor of the second motor. This makes it possible to reduce the torque and increase the rotational speed of the rotor of the second motor, thereby minimizing the size of the second motor.

In an embodiment of the invention, the powertrain further comprises a printed circuit board and the angular position measuring element of the first motor comprises a first sensor and the angular position measuring element of the second motor comprises a second sensor, the first sensor and the second sensor preferably being arranged on the printed circuit board. The printed circuit board is preferably flat.

In an embodiment of the invention, the powertrain further comprises a second freewheel arranged to prevent the second motor from driving the crankshaft in a rotational direction corresponding to a forward movement of the scooter.

The present invention further provides a scooter, comprising:

a powertrain according to one of the embodiments of the invention,

a wheel, and

an output drive chain or belt which meshes with the primary output sprocket cog, the secondary output sprocket cog and the pinion gears of the wheels.

The wheel is preferably the rear wheel of a scooter. Additionally, the treadmill may include a tension roller engaged with the output drive chain or belt to improve the tension of the output drive chain or belt.

Drawings

Other features and advantages of the invention will become apparent upon reading the following detailed description, and for an understanding of the other features and advantages of the invention, reference should be made to the accompanying drawings, in which:

figure 1 shows a schematic cross section of a first variant of a first embodiment of the invention;

figure 2 shows a schematic cross section of a second variant of the first embodiment of the invention;

figure 3 very schematically shows an internal kinematic chain of a powertrain according to an embodiment of the invention;

and

fig. 4 shows a side view of a powertrain and a transmission to the rear wheels of a scooter according to an embodiment of the invention.

Detailed Description

The present invention is described by way of particular embodiments and with reference to the accompanying drawings, but the invention is not limited thereto. The drawings or figures described are only schematic and are non-limiting.

For the purposes of this document, the terms "first" and "second" are used merely to distinguish between different elements and do not imply a sequence between these elements.

In the drawings, the same or similar elements may have the same reference numerals.

Fig. 1 shows a schematic cross section of a first variant of the first embodiment of the invention.

The powertrain 1 includes a crankshaft 2 and a secondary output chainring 4 having the same axis of rotation. This axis may be referred to as the first axis of rotation 30. Preferably, the crank shaft 2 is attached to two cranks 18. Preferably, the powertrain 1 includes a housing 19.

The powertrain 1 includes a main output sprocket ring 3 that is attached to the planet carrier 6, preferably at one end of the planet carrier 6, so as to rotate with the planet carrier 6.

Powertrain 1 also includes a secondary output chainring 4 attached to a secondary output hollow shaft 25 that passes through a sidewall of housing 19. The secondary output hollow shaft 25 is mounted in bearings around the crankshaft 2. The first free wheel 16 should be mounted between the crankshaft 2 and the secondary output hollow shaft 25 so that the secondary output chainring 4 cannot rotate at a lower speed than the crankshaft 2 when the crankshaft 2 is actuated in the normal pedaling direction.

The powertrain 1 includes a first motor 40 and a second motor 50. The first motor 40 includes a stator 46 and a rotor 47, which preferably includes magnets 48. The rotor 47 is arranged to rotate around the second rotation axis 31. The torque of the rotor 47 is transmitted to the sun gear 5 via the shaft of the rotor 43. The second motor 50 includes a stator 56 and a rotor 57, which preferably includes magnets 58. The rotor 57 is arranged to rotate around the third rotation axis 32. The torque of the rotor 57 is transmitted to the pinion gear 12 via the shaft of the rotor 53.

The function of the first freewheel 16 is to be able to transmit the full mechanical power from the crankshaft 2 to the drive chain 23 even if the motors 40, 50 are not energized. In the locked position, free wheel 16 integrates crankshaft 2 with secondary output sprocket 4, and in the free position, output sprocket 4 is free to rotate faster than crankshaft 2 when crankshaft 2 is actuated in the normal pedaling direction.

The powertrain 1 preferably includes current measuring elements of the first motor 40 and current measuring elements of the second motor 50.

Furthermore, the powertrain 1 preferably comprises a control unit, which is preferably attached to the printed circuit board 20. The printed circuit board 20 is preferably positioned perpendicular to the second 31 and third 32 axes of rotation.

Preferably, the first measurement magnet 42 is attached to one end of the shaft 43 of the first motor 40, and the second measurement magnet 52 is attached to one end of the shaft 53 of the second motor 50.

Preferably, the first sensor 41 is attached to the printed circuit board 20 and is substantially in line with the second axis of rotation 31. The first sensor 41 and the first measuring magnet 42 are part of an angular position measuring element of the rotor 47 of the first motor 40.

Preferably, the second sensor 51 is attached to the printed circuit board 20 and is substantially collinear with the third axis of rotation 32. The second sensor 51 and the second measuring magnet 52 are part of an angular position measuring element of the rotor 57 of the second motor 50.

The control unit controls the first motor 40 and the second motor 50 on the basis of the angular position of the first motor 40, the angular position of the second motor 50, the current of the first motor 40 and the current of the second motor 50, which information has been supplied to the control unit by means of measuring elements.

The control unit controls the second motor 50 with current or torque. The control unit controls the first motor 40 in angular position or angular velocity.

The powertrain 1 comprises an epicyclic gear comprising a first input element, an output element and a sun gear 5.

The power train 1 further comprises a deformable transmission element 15, such as a chain or belt, for transmitting rotation between the crankshaft 2 and the first input element. The deformable transmission element 15 forms a speed-change gear reduction system maintaining the direction of rotation.

In the first embodiment of the invention shown in fig. 1 and 2, the first input member is the ring gear 9 and the output member is the planet carrier 6. Preferably, the planet carrier 6 comprises at least one satellite gear 8 arranged to rotate around the planet pins 7. Preferably, the ring gear 9 meshes with the at least one planet gear 8 via its internal toothing 10. Preferably, the sun gear 5 meshes with at least one planet gear 8.

In one embodiment of the invention, the first gear 13 is integral with the crank shaft 2. The first gear wheel 13 is connected to the second gear wheel 14 by means of a deformable transmission element 15. The second gear 14 is integral with the ring gear 9. Preferably, the first gear 13 has a larger diameter than the second gear 14 in order to increase the rotation speed with respect to the rotation speed of the crank shaft 2. For example, the diameter of the first gear 13 may be 1.5 to 3 times as large as the diameter of the second gear 14.

In the normal operating mode, the powertrain 1 according to the first embodiment of the invention functions as follows. The crankshaft 2 and the second motor 50 drive the ring gear 9, and the crankshaft 2 and the ring gear 9 are driven by the deformable transmission element 15. The ring gear 9 is the first input of the epicyclic gear. The first motor 40 drives the sun gear 5, which is the second input of the epicyclic gear. The ring gear 9 and the sun gear 5 drive a carrier 6, which is the output of the epicyclic gear. The planet carrier 6 drives the main output sprocket toothed disc 3. The rotational speed of the main output sprocket cog will be equal to the weighted sum of the rotational speed of the ring gear 9 and the rotational speed of the sun gear 5. Thus, by increasing the rotational speed of the sun gear 5, the speed of the main output sprocket 3 can be increased, thereby keeping the rotational speed at the crankshaft 2 constant. Thus, the powertrain is a Continuously Variable Transmission (CVT).

The pinion gear 12 is connected to the rotor 57 of the second motor 50 such that the pinion gear rotates together with the rotor 57. The pinion gear 12 directly meshes with the external tooth portion 11 of the ring gear 9. The diameter of the pinion 12 is smaller than the diameter of the ring gear 9 in order to reduce the rotational speed compared to the rotational speed of the motor.

The sun gear 5 is connected to the rotor 47 of the first motor 40 such that it rotates together with the rotor 47.

The planet carrier 6 passes through a side wall of the housing 19 so that the primary output chainring 3 attached to the planet carrier 6 is located outside the housing 19.

When the crank shaft 2 is rotated in the normal pedaling direction, the first free wheel 16 prevents the secondary output sprocket 4 from rotating slower than the crank shaft 2. The purpose of this freewheel 16 is that the gear ratio of the powertrain cannot be less than 1: 1. In the case of high pedaling torques, this position of the first freewheel 16 makes it possible to avoid high torques in the rest of the transmission. Thus, certain components of the powertrain are not subjected to high torque. In this way, when the powertrain comprises a deformable transmission element 15, such as a belt, particular attention is paid to retaining the epicyclic gear and the transmission system between the crankshafts 2.

Fig. 2 shows a variant of the powertrain 1, in which a second freewheel 17 is mounted between the crankshaft 2 and the first gear wheel 13. The freewheel 17 functions to prevent the second motor 50 from driving the crankshaft 2 when the crankshaft 2 is actuated in the normal pedaling direction.

When the crank shaft 2 is actuated in the normal depressing direction, the second free wheel 17 drives the first gear 13, but when the crank shaft 2 is actuated in the normal depressing direction, the first gear 13 cannot drive the crank shaft 2.

The addition of the second freewheel 17 provides greater control flexibility because it allows the second motor 50 to rotate without operating the crankshaft 2. This enables, for example, the motor to be operated by means of the accelerator without the rider operating the crank.

Fig. 3 very schematically shows an internal power train of the powertrain 1 according to an embodiment of the invention. According to this power train, the rider provides input power to the system via pedals 21, driving crankshaft 2 via crank 18. A first gear 13 integral with the crankshaft 2 drives the ring gear 9 via a deformable transmission element 15, so that it rotates faster than the crankshaft 2. A pinion 12 integral with the rotor 57 of a second motor (not shown in this simplified figure) is connected to the ring gear 9 at a fixed ratio. The ring gear 9 is the first input of the epicyclic gear. The sun gear 5, integral with the rotor 47 of the first motor (not shown in this simplified figure), is the second input of the epicyclic gear. The sun gear 5 and the ring gear 9 are connected together by means of a planet carrier 6 comprising at least one planet gear 8. One or more planet gears 8 are held by the shaft 7 of the planet carrier 6 and are free to rotate. The carrier 6 is an output portion of the epicyclic gear.

The arrows in fig. 3 show the direction of rotation of the various components during normal operation of the powertrain 1. For the sake of simplicity and clarity of the illustration in fig. 3, the different transmission components (wheels, pinions, belts) are smooth and it may be advisable to perform a friction transmission. This does not, of course, preclude the use of toothed teeth for the manufacture of gears or toothed belts.

FIG. 4 shows a side view of the cycle truck of the embodiment of the present invention: power train 1, output drive chain 23, rear wheel pinion 24 and tension roller 22. The output drive chain 23 includes an upper section 23a, a lower section 23b and an intermediate section 23 c. Intermediate section 23c is a portion of output drive chain 23 between primary output sprocket cog 3 and secondary output sprocket cog 4.

The function of the tension roller 22 is to remove slack in the output drive chain or belt 23 when the transmission is in a loaded condition. The tensioning roller allows the intermediate section 23c to remain taut. The tension roller 22 may be integrated into the powertrain 1 or attached to the frame of the scooter. The tensioning roller is positioned such that it is in contact with the lower section 23 b. It is also possible to consider a static operation without the tension roller 22.

In the normal operating mode of the powertrain 1, the main output chainring 3 drives the output drive chain or belt 23. Secondary output sprocket 4 preferably meshes with primary output sprocket 3 on the same drive chain 23 and rotates at a higher speed than crankshaft 2. The secondary output chainring 4 is disengaged from the crankshaft 2 by means of the first free wheel 16. The first function of the secondary output sprocket 4 is to guide the drive chain 23 around the crankshaft 2, thereby increasing the distance between the upper chain segment 23a and the lower chain segment 23 b. In this way, with the propulsion system mounted on the bicycle frame, there is sufficient space for the right rear base of the frame to pass through. The right rear frame base is a frame tube that connects the rear wheel attachment point to the powertrain mounting bracket. The right rear frame base is not shown in fig. 4.

In some particular operating modes, different from the normal operating mode of the powertrain 1, the first freewheel 16 locks and prevents the secondary output chainring 4 from rotating slower than the crankshaft 2. In this case, secondary output sprocket cog 4 drives, in whole or in part, output drive chain 23 and, therefore, main output sprocket cog 3 as well. If the electrical system is turned off and/or the power assist device is disabled and the lowest gear ratio of the powertrain 1 is selected (by the user or by the control system), then all of the power of the rider will be transmitted to the drive chain 23 via the secondary output sprocket cog 4. Thus, the rest of the transmission is unloaded and the mechanical efficiency of the transmission is high.

The secondary output chainring 4 may also transmit some power during normal operation of the powertrain 1 if the rider's instantaneous torque exceeds a certain threshold and the first motor 40 is saturated at its maximum torque. During the duration of the depression of the pedal 21, the instantaneous value of the gear ratio of the powertrain will decrease and, if the programmed gear ratio is low, the first free wheel 16 can activate and drive the secondary output sprocket 4 which transmits the rider's excess torque to the drive chain 23. The interaction of the secondary output chainring 4 and the first freewheel 16 prevents the gear ratio of the powertrain from reaching a value less than 1.

A first method of smoothing power assist according to the present invention is shown in fig. 5. The first method involves smoothing the torque provided by the two electric motors by transferring the thrust imparted by the second motor over time. The graph in fig. 5 shows the torque 103 of the user, the torque 104 of the first motor and the torque 15 of the second motor in a graph of the torque 101 over the crank angle 102. The user transmits via the crank 18 the force that he applies to the crank shaft 2, which induces a reciprocating torque in the crank shaft 2. When one of the two cranks is close to horizontal, the torque provided by the user is maximum. The first motor 40 is preferably adjusted to operate at a rotational speed that is proportional to the speed of the crank angular speed of the crank 40. When the user exerts a thrust on one of the two cranks 18, the crank accelerates, causing a delay in the angular position of the first motor 40. The first motor corrects the delay by increasing its torque. Thus, the torque provided by the rider and the torque provided by the first motor 40 are relatively in phase.

The present invention proposes phase shifting the torque applied to the second motor 50 to fill the torque valleys of the first motor 40 to smooth the total torque supplied to the rear wheels. This stabilizes the adjustment, improves efficiency, reduces stress in the transmission, and allows the size of the first motor 40 to be reduced. In order to achieve this smoothing method, the current signal measured at the first motor 40 can be shifted or filtered, for example, as a function of the angular position of the crank, so as to cause a shift in the torque applied to the second motor 50.

Fig. 6 shows a method of preventing transmission slip, which may be applied to a powertrain according to the present invention. The graph in fig. 6 shows the torque 103 of the user, the torque 104 of the first motor and the torque 15 of the second motor in a graph of the torque 101 over the crank angle 102. One can provide a high torque value in the crank at low pedaling speed in a short period of time. Since the torque applied to the crank is transmitted directly opposite to the first motor 40 (according to the torque law of the epicyclic gear), this means that the first motor 40 must rapidly transmit a large amount of torque and therefore consume a large amount of current in order to follow its position set point. In order to limit the energy consumption and protect the windings and gears of the first motor 40, the invention proposes to limit the maximum torque transmitted by said first motor 40. The drawback of this limitation is that when the first motor 40 is saturated at its maximum torque (current limit), it will no longer be able to properly follow its position servo set point, which will create a slip sensation during which the rider will feel that his gear ratio is falling during the brief moments of excessive pedal thrust. Thus, the powertrain is arranged to apply a delay to the current or torque setpoint of the second motor 50 such that the assist peak of the second motor 50 is in phase with the torque valley of the first motor 40.

The anti-slip method proposed by the present invention comprises using the second motor 50 as a generator to brake the movement of the rider when the rider exerts excessive thrust on the pedals. During this excessive thrust, the actual level of electric assistance will decrease, but the first motor 40 will be able to follow its angular position set point and therefore the set point gear ratio. Fig. 6 shows a situation in which the torque provided by the user increases rapidly and reaches a high value. The method according to the invention reduces the setpoint current (and therefore the torque) of the second motor 50 and applies a negative current (negative torque) even for a short time, to allow the first motor 40 to follow its angular position setpoint to the maximum extent without providing excessive torque. During the period when the second motor 50 brakes the crank, the current supplied by the second motor 50 may be battery powered or supplied to the first motor 40. The re-emission region is indicated by hatching in fig. 6. Thus, the powertrain is arranged such that when the first motor 40 is no longer able to follow its angular position setpoint, the current or torque setpoint of the second motor 50 is reduced to a negative current value or negative torque value.

It should be noted that the arrangement of the powertrain according to the invention is compatible with the powertrain variants described in document WO2013/160477 or in document WO2016/034574, or with other known powertrain variants.

In other words, the invention relates to a powertrain 1 for a scooter. Powertrain 1 includes a primary output sprocket cog 3 and a secondary output sprocket cog 4 that is coupled to crankshaft 2 through a first freewheel 16. The coupling between the crankshaft 2 and the main output chainring 3 is via a deformable transmission element 15 and an epicyclic gear.

The present invention has been described in connection with specific embodiments, which are fully illustrative and should not be considered as limiting. In general, the invention is not limited to the examples shown and/or described above. The use of the verbs "comprise", "include", "including" or any other variation and inflections thereof in no way excludes the presence of elements other than those mentioned. The use of the indefinite article "a" or "an" to introduce an element does not exclude the presence of a plurality of such elements. Reference signs in the claims do not limit their scope.