FR3084126A1 - TRANSMISSION SYSTEM FOR A ROLLING ELECTRIC MACHINE COMPRISING TWO HOUSES CLOSED BY THE SAME PLATE AND A TRANSMISSION MECHANISM FORMING BRIDGE BETWEEN THE SAME - Google Patents

Abstract

The invention relates to a transmission system (10) for an electric rolling machine, comprising: - two housing bodies (12, 14) each closed by a same plate (16) so as to define a first and a second housing, the first case (12) containing a speed variator (32) extending between two shafts housed inside the case and forming, for one, an input shaft (34) capable of being driven in rotation by a motor electric and, for the other, an output shaft (36), the second box (14) enclosing a speed reduction system (68) between an input shaft (66) and an output shaft (26, 28 ), -a belt or chain transmission mechanism (18) forming a bridge between the output shaft (36) of the first housing and the input shaft (66) of the second housing.

Description

IMPROVED TRANSMISSION SYSTEM

The present invention relates to a transmission system for a rolling electric vehicle.

Transmission systems are known for an electric rolling machine which transmit mechanical torque to an output shaft connected to one or more wheels of the machine from an electric motor.

When the machine is a light vehicle, for example with two or three wheels, the weight of the engine and the weight of the battery are constraints which the designer must face.

To reduce the weight of the engine, designers tend to choose a small engine which is therefore lighter.

However, such an engine rotates at higher rotational speeds than a larger engine.

It is therefore necessary to reduce the speed of rotation between the output shaft of the engine and the output shaft (s) connected to the wheels of the machine and therefore to design a suitable transmission system.

For certain types of light rolling electric vehicles it is even desirable to seek to further reduce their weight.

It would therefore be particularly interesting to design a new architecture for the transmission system for an electric vehicle traveling at a reduced weight.

The present invention thus relates to a transmission system for a rolling electric vehicle, characterized in that it comprises:

- two housing bodies which are each closed by a single plate so as to define a first and a second housing, the first housing containing a speed controller extending between two shafts housed at least partially inside the housing and forming , for one, an input shaft which is capable of being rotated by an electric motor and, for the other, an output shaft, the second housing containing a speed reduction system between a shaft input and at least one output shaft such as a gear wheel drive shaft,

-a belt or chain transmission mechanism forming a bridge between the output shaft of the first housing and the input shaft of the second housing.

This new configuration makes it possible to limit the on-board weight insofar as the same plate is used to close two housing bodies.

In addition, the arrangement of the belt or chain transmission mechanism between the first casing and the second casing makes it possible to limit the size and therefore the weight of the belt or of the chain relative to a positioning of the same mechanism after the second housing according to the kinematic order of the transmission.

The rolling electric vehicle can be an electric vehicle, a walking machine.

According to other possible characteristics:

-the belt or chain transmission mechanism is outside the two housings;

the two housings extend on the same side of the plate;

the belt or chain transmission mechanism extends on the opposite side of the plate;

the plate is intended to be mounted on a chassis of the machine;

the plate is intended to be mounted on a chassis of the machine by means of mounting members which absorb vibrations and shocks;

the plate is made of a more rigid material than the material constituting the housing bodies;

the plate is a heat sink;

the transmission mechanism is configured to ensure speed reduction;

-the transmission mechanism includes:

a first pinion which is carried by the output shaft of the first housing and mounted integral in rotation with said shaft, a second driven pinion carried by the input shaft of the second housing and mounted integral in rotation with said shaft, a coiled synchronous belt around the first and second gables;

the speed variator is a belt speed variator comprising a drive pulley mounted on the input shaft of the first housing, a receiving pulley mounted on the output shaft of said first housing and a belt wrapping around said pulleys , each of said pulleys being a flange pulley of which at least one flange is capable of moving in the direction of approaching or spacing relative to the other flange;

the system comprises a system for controlling the movement of one of the flanges of one of the two pulleys;

the control system for one of the flanges of the receiving pulley comprises a servomotor comprising a motor shaft which mechanically cooperates with a drive control member in axial displacement of the controlled flange of the receiving pulley;

the speed reduction system of the second housing comprises an input pinion carried by the input shaft of said second housing and which meshes in a reduction ratio with a ring gear mounted on the output shaft of said second housing, the speed reduction system further comprising a free wheel disposed between the input pinion and the input shaft

-the output shaft of the second housing is formed by two half-shafts, the speed reduction system of the second housing comprising a differential of which the toothed ring is part and internally houses satellites engaged with planets which are integral in rotation of the two output half-shafts.

The invention also relates to an electric rolling machine comprising a transmission system as briefly mentioned above.

Other characteristics and advantages of the invention will become apparent during the description which follows, given solely by way of nonlimiting example and made with reference to the appended drawings, in which:

FIG. 1 is a general schematic view in cross section of a transmission system according to an embodiment of the invention;

FIGS. 2 and 3 are perspective views showing the general architecture in space of the transmission system of FIG. 1 respectively in front view and in rear view;

FIG. 4 is an exploded view of the main components of the transmission system of FIGS. 1 to 3.

As shown diagrammatically in FIG. 1 and designated by the general reference noted 10, a transmission system for an electric rolling machine comprises several components, namely two housing bodies or casings 12 and 14 which are each closed by the same plate 16 forming a support, thus defining a first box called a speed variator box 12 and a second box called a speed reduction box 14.

The two housings are connected to each other by a transmission mechanism 18 which, in general, is a belt or chain mechanism and, in the present embodiment, is a belt mechanism, preferably synchronous belt.

The rolling electric machine 30 partially shown in FIG. 1 comprises, on the one hand, the transmission system 10 of which an electric motor 20 (for example a traction motor) forms part, and, on the other hand, two wheels 22 and 24 each carried by a shaft 26, 28. Each shaft is called the drive wheel of a machine wheel. The two shafts 26 28 can also be qualified as half-shafts. The machine also includes a battery for supplying the engine, not shown.

The transmission system 10 transmits a rotational movement imposed by the electric motor 20 to the wheels 22 and 24 of the machine 30.

It will be noted that the electric motor 20 is generally small and light, which results in high rotational speeds at the level of the motor shaft 34. In practice, such a motor can be characterized by a speed / torque ratio greater than 1000 revolutions per minute / Nm. The transmission system which will be described below makes it possible in particular to reduce this speed before driving the wheels of the machine.

The speed variator housing 12 contains a speed variator, for example with a belt, 32 which extends between two shafts 34 and 36 housed at least partially inside the housing. The shaft 34 is an input shaft of the housing which is connected to the electric motor 20 and which is therefore able to be driven in rotation by the motor. The shaft 36 is an output shaft of the housing which is connected to the transmission mechanism 18. The shaft 36 is mounted on the bottom of the housing 12 by one of its two opposite ends so as to provide guidance in rotation.

The belt speed variator 32 more particularly comprises a driving or driving pulley 38 mounted on the input shaft 34, a receiving or driven pulley 40 mounted on the output shaft 36 and a belt 42 illustrated in dotted lines in the figure 1 and which wraps around the two pulleys.

Each of the pulleys 38, 40 is a flange pulley which comprises at least one mobile flange (here only one flange per pulley is mobile) capable of approaching or moving away from the other flange.

In the present embodiment, the transmission system 10 comprises a control system 44 for one of the flanges of one of the two pulleys, the other movable flange of the other pulley not being controlled. This control system 44 can be actuated on the basis of a manual action by the user of the machine, for example, by means of a lever, a pedal, the movement of which activates electronics which acts on the system 44, in particular as described below. Alternatively, the movement of the flange can be controlled only mechanically from a manual action of the user on a cable, a lever, etc.

More particularly, the driving pulley 38 coupled to the electric motor comprises a fixed flange 38a secured to the input shaft 34 and a movable flange 38b which is linked to a known belt tensioning system produced here, for example, in the form a spring 38c exerting an axial force on said flange 38b.

The receiving pulley 40 comprises, for its part, a fixed flange 40a secured to the output shaft 36 and a movable flange 40b subject to the control system 44 which controls the movement of said flange 40b. Alternatively, the piloting control is exerted on a movable flange of the other pulley. It will be noted that the receiving pulley can be controlled in opening and closing.

The control system 44 comprises in this embodiment an electric servomotor 46 comprising a motor shaft 48 which cooperates mechanically with a control member for driving the displacement of the flange 40b. More particularly, the drive shaft 48 carries, at its opposite end 48a, a pinion 50 which cooperates by meshing with the external toothed part of a nut 52 mounted around a part 54 forming a screw in its external part which cooperates with the 'nut. The nut 52 is also mounted on the movable flange 40b via, for example, a ball bearing 56.

It will be noted that other mechanisms for transmitting an axial movement of the flange 40b can be envisaged. For example, a mechanism using a worm screw can be used directly at the output of the servomotor 46 to cause the axial displacement of the nut 52.

The transmission mechanism 18 more particularly comprises a belt 60 wound, on the one hand, around a first pinion 62 carried by the output shaft 36 of the housing 12 (the pinion 62 is mounted on the end of the shaft which is opposite to that mounted on the bottom of the housing 12) and mounted integral in rotation with said shaft and, on the other hand, around a second driven pinion 64 carried by an input shaft 66 of the second housing 14 and mounted integral in rotation of said shaft.

The belt 60 thus forms a bridge between the output shaft 36 of the first housing 12 and the parallel input shaft 66 of the second housing 14.

The belt 60 is for example a synchronous belt which makes it possible to ensure a transmission of movement without slipping. In this embodiment, the transmission mechanism 18 is configured to ensure a reduction in speed between the two shafts. This speed reduction is for example implemented thanks to the ratio between the diameters of the small pinion 62 and the large pinion 64.

The arrangement of the transmission mechanism 18 between the two housings rather than downstream of the second housing 14 makes it possible to intervene, at this stage of the transmission, on high rotational speeds and low torques. Despite a high speed of rotation, the use of a belt in the mechanism 18 makes it possible to control the noise. A low torque makes it possible to use a relatively thin belt section (limited weight). Thus, the second housing 14 operates on lower rotation speeds and higher torques than on the previous transmission stage. Therefore, the use of pinions in the speed reduction system of the second housing 14 which will be described makes it possible to be relatively silent (low speed) and is suitable for transmitting a high torque in a small footprint.

The second housing 14 (speed reduction) more particularly comprises the input shaft 66 already described and a speed reduction system 68 between this shaft and the two output shafts 26 and 28 connected respectively to the wheels 22 and 24. L 'shaft 66 is mounted on the bottom of the housing 14 by one of its two opposite ends so as to provide rotational guidance. The opposite end of the shaft 68 is that on which the pinion 64 is mounted.

The speed reduction system 68 comprises an input pinion 70 which is carried by the input shaft 66 and a ring gear 72 of larger diameter than the pinion and mounted on the output shafts 26 and 28, the pinion meshing with the ring gear in a reduction ratio.

The speed reduction system further comprising a free wheel 74 mounted between the pinion 70 and the shaft 66 and which makes it possible to cut the electric motor when the machine is in the deceleration or downhill phase.

In the present embodiment, the speed reduction system 68 may also include a differential 76 known per se, including the toothed ring 72 and satellites 76a and 76b housed inside the ring and which are engaged with planetary 76c and 76d integral in rotation with the two respective output shafts 26 and 28. The satellites are mounted free in rotation on their axes.

This differential allows the power from the engine to be transmitted to each of the drive wheels at different speeds.

In another embodiment not shown where the output shaft connected to the wheels is unique, the differential is not present.

The two housings 12 and 14 as well as the transmission mechanism 18 are all mounted on the plate 16 forming a common support which is itself mounted on a chassis 80 of the machine. This common support which ensures the closing function of the housing bodies 12 and 14 thus makes it possible to reduce the number of parts of the transmission system and therefore to reduce their weight. The mounting on the chassis is for example carried out by means of mounting members damping vibrations and shocks 82.

Note that the motor 20 is also mounted on the plate 16, as is the servomotor 46 (optional). The plate thus plays a central role in bringing together most of the components of the transmission system.

This plate is made of a material which is more rigid than the material constituting the housing bodies 12 and 14 (the latter material is more generally a plastic type material in particular for reasons of weight) in order to stiffen the transmission system and fix it to the chassis of the machine.

The plate can play a role of heat sink (in particular to dissipate the calories generated by the engine), on the one hand, because of its central function of grouping together the components of the system and, on the other hand, by being produced in a particularly thermal conductive material such as aluminum. The plate having relatively large dimensions compared to the components of the system, the heat exchange surface between said plate and the surrounding air is relatively large.

As shown generally in Figure 1, the two housings 12 and 14 extend on the same side of the plate 16, while the transmission mechanism 18 extends on the opposite side and is therefore disposed at the outside of the two boxes 12 and 14. Alternative arrangements are however possible. The transmission mechanism 18 can alternatively be protected by a cover fixed on the plate 16.

The plate 16 is drilled in several places in order to allow the passage of the different shafts or axes 34, 36, 66 and 26 which are here parallel to each other.

The production of such through holes makes it possible to obtain precise dimensions both for the diameter of the holes and for the dimensions between the holes. This is particularly advantageous for the holes intended to receive the shafts 36 and 66 since the distance between the two shafts is thus guaranteed. This arrangement thus facilitates the mounting of the mechanism 18 in connection with the housings 12 and 14. The above also applies to all the shafts mounted passing through on the plate.

FIG. 2 shows the spatial configuration of the two housings 12 and 14 on the plate 16 according to a view taken from the side of the wheel 24 of FIG. 1 and the transmission mechanism 18 can be seen in the background.

FIG. 3 shows this same spatial configuration as well as that of the transmission mechanism 18 according to a view taken from the wheel 22 of FIG. 1. A tension roller 84 which provides a greater or lesser tension of the belt 60 is shown. This roller is also mounted on the plate 16. The plate also makes it possible, in general, to fix various accessories.

FIGS. 2 and 3 provide a better understanding of the central role of grouping the components of the transmission system 10 played by the plate 16.

The two boxes are thus arranged one next to the other (here one below the other, the box 14 being at the level of the wheels while the box 12 being above these wheels), and grouped as close as possible to each other in order to reduce the overall dimensions in three dimensions of these two housings and make the assembly as compact as possible. More particularly, the housing 12 being elongated relative to the housing 14, the latter is not placed in alignment with the length of the housing 12 (the representation of FIG. 1 might suggest such a configuration but it does not is nothing) but alongside this length, substantially centered with respect to the housing 12. The transmission system thus configured offers a one-piece appearance.

FIG. 4 is an exploded perspective view of the main components of the transmission system 10, namely the housing body 12 which contains the variable speed drive 32 and its elements, the housing body 14 which contains the reduction system speed 68, differential 76 (optional), plate 16, belt transmission mechanism 18 and electric motor 20.

It will be noted that the plate 16 is configured to locally adapt to the shape of the components of the system with which it cooperates. In particular, it has a local thickness adapted to act as a cover for the two boxes and an external contour also adapted to the shape of the boxes in order to reduce as much as possible the non-useful surface of the plate and therefore the on-board weight.

As already mentioned above in connection with the mounting of the transmission mechanism 18, the central role of grouping played by the support plate 16 simplifies the assembly operations of the various components once the plate has been placed on the chassis of the gear.

Furthermore, the rigidity of the plate makes it possible, on the one hand, to guarantee a fixed center distance between the different shafts / axes mounted through said plate and, on the other hand, to take up the forces and torques generated by each component or unit of transmission of the transmission system (motor, speed variator, belt or chain transmission mechanism, speed reducer).

It will be noted that the transmission system according to the invention offers a reduced number of boxes, which again simplifies the mounting operations.

Note also that the engine acceleration phase is done in two successive stages:

the motor is accelerated to its maximum speed (close to the point of optimal efficiency) which corresponds substantially to one third of the maximum speed of the machine, while the speed variator ratio remains unchanged;

the ratio of the variable speed drive is then changed to the maximum speed of the machine so that the motor remains at its point of optimum efficiency.

Claims (15)

1. Transmission system (10) for an electric rolling machine, characterized in that it comprises: - two housing bodies (12, 14) which are each closed by the same plate (16) so as to define a first and a second housing, the first housing (12) containing a variable speed drive (32) extending between two shafts housed at least partially inside the housing and forming, for one, an input shaft (34) which is able to be driven in rotation by an electric motor and, for the other, a shaft output (36), the second case (14) enclosing a speed reduction system (68) between an input shaft (66) and at least one output shaft (26, 28) such as a drive shaft for wheel of the craft, -a belt or chain transmission mechanism (18) forming a bridge between the output shaft (36) of the first housing and the input shaft (66) of the second housing. 2. Transmission system according to claim 1, characterized in that the belt or chain transmission mechanism (18) is outside the two housings (12, 14). 3. Transmission system according to claim 1 or 2, characterized in that the two housings (12, 14) extend on the same side of the plate (16). 4. Transmission system according to claim 3, characterized in that the belt or chain transmission mechanism (18) extends on the opposite side of the plate. 5. Transmission system according to one of claims 1 to 4, characterized in that the plate (16) is intended to be mounted on a chassis (80) of the machine. 6. Transmission system according to claim 5, characterized in that the plate (16) is intended to be mounted on a chassis (80) of the machine by means of mounting members damping vibrations and shocks ( 82). 7. Transmission system according to one of claims 1 to 6, characterized in that the plate (16) is made of a more rigid material than the material of the housing bodies. 8. Transmission system according to one of claims 1 to 7, characterized in that the plate (16) is a heat sink. 9. Transmission system according to one of claims 1 to 8, characterized in that the transmission mechanism (18) comprises: a first pinion (62) which is carried by the output shaft (36) of the first housing (12) and mounted integral in rotation with said shaft, a second driven pinion (64) carried by the input shaft (66) of the second housing (14) and mounted integral in rotation with said shaft, a synchronous belt (60) wound around the first and second pinions. 10. Transmission system according to one of claims 1 to 9, characterized in that the speed variator (32) is a belt speed variator comprising a drive pulley (38) mounted on the input shaft (34 ) of the first housing, a receiving pulley (40) mounted on the output shaft (36) of said first housing and a belt (42) winding around said pulleys, each of said pulleys being a flange pulley including at least one flange (38b, 40b) is able to move in the direction of approaching or spacing relative to the other flange. 11. Transmission system according to claim 10, characterized in that it comprises a control system (44) in movement of one of the flanges of one of the two pulleys. 12. Transmission system according to claim 11, characterized in that the control system (44) of one of the flanges of the receiving pulley comprises a servomotor (46) comprising a motor shaft (48) which cooperates mechanically with a member of control (50, 52, 56) for driving the axial displacement of the controlled flange (40b) of the receiving pulley (40). 13. Transmission system according to one of claims 1 to 11, characterized in that the speed reduction system (68) of the second housing (14) comprises an input pinion (70) carried by the input shaft (66) of said second housing and which meshes in a reduction ratio with a ring gear (72) mounted on the output shaft 26, 28) of said second housing, the speed reduction system further comprising a free wheel (74) disposed between the input pinion and the input shaft. 14. Transmission system according to claim 13, characterized in that the output shaft of the second housing is formed by two half-shafts (26, 28), the speed reduction system (68) of the second housing comprising a differential (76) of which the toothed ring is part and internally houses satellites (76a-b) engaged with planets (76cd) which are integral in rotation with the two output half-shafts. 15. Rolling electric machine comprising a transmission system according to one of the preceding claims.