WO2018130420A1

WO2018130420A1 - Gearmotor

Info

Publication number: WO2018130420A1
Application number: PCT/EP2018/000008
Authority: WO
Inventors: Luigino Pozzo
Original assignee: Pmp Pro-Mec S.P.A.
Priority date: 2017-01-11
Filing date: 2018-01-08
Publication date: 2018-07-19
Also published as: IT201700002279A1

Abstract

Gearmotor for direct drive to a driving wheel of an electric traction vehicle, wherein a traction motor, provided with a respective driving shaft, is integrated with a gear-reducing device comprising gears, which is connectable to the driving wheel, the driving shaft constituting the first pinion of the gear-reducing device.

Description

DESCRIPTION

GEARMOTOR

Field of the invention

The present invention relates to a gearmotor for direct drive to the wheel of an electric traction vehicle according to the characteristics of the pre-characterizing part of claim 1.

The present invention also relates to an electric traction vehicle with said gearmotor with an integrated brake according to the characteristics of the pre-characterizing part of claim 13.

Prior art

In the field of the transmission of motion to the driving wheels of vehicles, particularly industrial vehicles, e.g. tractors, forklift trucks, operating machinery, the use of gearmotors is known in which an electric motor is associated with a mechanical gear- reducing device that transmits motion to the wheels.

Solutions are also known in which the gearmotor also integrates braking means according to different configurations.

Steering is managed by an electronic system that monitors the signals coming from the speed sensors present on each of the two motors and by a transducer that measures the steering angle.

Current trends are focussing on the use of increasingly fast and compact electric motors, in order to reduce the external overall dimensions of the gearmotor system and final users require increasingly silent vehicles.

Patent application WO2007022865, in the name of the same applicant describes a gearmotor with integrated brake for direct drive to the wheel of an electric traction vehicle where the traction motor is integrated with a direct drive to the driving wheel, and where the traction motor includes a passing driving shaft that on the wheel side includes a pinion that internally gears in an integrated transmission-reducer system for the traction motion to the wheel in a respective gear chamber and on the other side opposite to the wheel is keyed to a braking system also integrated and cased with the group, in a respective opposite braking chamber forming a detachable motor-brake unit and in which the transmission-reducer system is housed in a structural supporting casing connectable to the vehicle and the motor unit has its own supporting casing that is fixed as a cover to the structural supporting casing covering the reducer system and allowing free access following its removal.

Patent application WO 2013/102484 describes a gearmotor with integrated brake for direct drive to the driving wheel of an electric traction vehicle where a traction motor is integrated with a gear-reducing device connectable to the driving wheel of the electric traction vehicle in correspondence with a hub, where the gear-reducing device is housed into a structural supporting box connectable to the vehicle by means of fixing holes, the traction motor having a supporting casing fixed to the box as a cover, the box and the cover constituting a single structural supporting casing of the gearmotor, where the traction motor is a motor whose transmission shaft is coupled in correspondence of a first pinion of the gear-reducing device or is integral with it and where the motor control inverter is housed in correspondence of the closure head of the motor.

Patent application DE 10 2012 1 12371 describes a drive unit having a suspended decoupling element for impact sound decoupling of the machine housing at the flange. The decoupling element is provided with a metallic, disc-like spring which is arranged in an axial direction between the machine housing and the flange. The spring is fixed to the flange. A piston engine of the machine has a respective drive shaft that communicates with an output element of a reduction unit for driving a rotatable hub. A gear of the reduction unit is shaped as a transmission input shaft. The gear of the reduction unit shaped as a transmission input shaft is coupled with toothed means in correspondence of the drive shaft of the piston engine. The coupling means consist of an external toothing of the drive shaft coupling with an internal toothing of the gear of the reduction unit shaped as an input shaft. Patent application US 2014/033846 describes a propulsive apparatus for use in an electric vehicle including a gear rotatable by a propulsive motor and having first teeth, and a constant velocity joint having an outer member which includes a larger- diameter portion having second teeth on an outer wall surface thereof. The second teeth serve as part of a speed reducer mechanism, which is thus interposed between the propulsive motor and the constant velocity joint.

Problems of the prior art

The prior art solutions are often not very suitable for the use of compact motors, which are characterised by high rotational speeds.

Furthermore, the prior art solutions have large overall dimensions, also due to the use of large motors, with the consequence that they are subject to greater costs as well as greater weight and larger overall dimensions of the vehicles using such devices.

In order to reduce as far as possible the sizes of the gearmotor as a whole, normally one tries to reduce the electric motor, adopting reduction ratios such that the motor can reach speeds for example of 8000-12000 revolutions per minute. In this way it is possible to obtain a reduction in the motor sizes by about 50% with respect to the traditional motors for this type of application, which operate at speeds of the order of

5000 revolutions per minute.

However, by increasing the rotational speed of the motor, one also has a louder noise, as well as an increase in the vibrations that can be generated in the gearmotor system as a whole.

Aim of the invention

The aim of the present invention is to provide a gearmotor provided with a motor having a high rotational speed, such as of the order of 8000-12000 revolutions per minute, while ensuring high levels of silence and low vibrations.

Concept of the invention

The aim is achieved by the characteristics of the main claim. The sub-claims represent advantageous solutions. Advantageous effects of the invention

The solution according to the present invention, by the considerable creative contribution the effect of which constitutes an immediate and important technical progress, has various advantages, among which a more compact gearmotor and the possibility to reach high rotational speeds with a low noise and low vibrations.

Furthermore, the solution according to the present invention is advantageous also in terms of reliability and resistance to wear.

Moreover, thanks to the solution according to the invention, it is possible to advantageously obtain a reduction in the length of the driving shaft of the transmission and a condition of better rotary support of the driving shaft itself, advantageously obtaining a reduction in the radial load on the pinion and thus in the flexure thereof, which would be particularly detrimental at high operating speeds. Description of the drawings

In the following a solution is described with reference to the enclosed drawings, which are to be considered as a non-exhaustive example of the present invention in which:

Fig. 1 shows a sectional view of a gearmotor of the prior art.

Fig. 2 shows an enlarged view of the portion indicated by "A" in Fig. 1.

Fig. 3 shows a sectional view of a gearmotor made in accordance with the present invention.

Fig. 4 shows an enlarged view of the portion indicated by "B" in Fig. 3.

Fig. 5, Fig. 6 and Fig. 7 schematically show only the motor of the gearmotor made in accordance with the present invention and show part of the assembly sequence. Fig. 8 schematically shows the coupling between the motor and the gear-reducing device of the gearmotor made in accordance with the present invention.

Fig. 9 and Fig. 10 schematically show only the driving shaft of the motor of the gearmotor made in accordance with the present invention. Description of the invention

With reference to the figures (Fig. 1 , Fig. 2), in the prior art solutions of an integrated gearmotor made up of a motor which is mechanically connected to a corresponding gear-reducing device (4) the gear-reducing device (4) and the motor are generally two different and separate members which are mechanically coupled with each other by means of the coupling between the driving shaft (8) of the motor and a first pinion (14) of the gear-reducing device (4), the first pinion (14) constituting the input interface for the set of gears (2) constituting the gear-reducing device. The coupling between the driving shaft (8) of the motor and the first pinion (14) of the gear- reducing device (4) occurs by means of locking keys or grooved sections that rotationally constrain the driving shaft (8) and the first pinion (14) to each other in such a way that the rotation imparted to the driving shaft (8) by the respective motor is translated into a corresponding rotation of the first pinion (14) of the gear-reducing device (4) which, in its turn, rotates the gears (2) of the gear-reducing device (4) to transmit the motion to the hub (1) integral with a driving wheel to move a respective electric traction vehicle.

With reference to the figures (Fig. 3, Fig. 4, Fig. 5, Fig. 6), the gearmotor (5) for direct drive to the wheel according to the present invention allows to obtain one single body consisting of the gear-reducing device (4), the motor (6), the brake (3). A compact and resistant solution is thus obtained with all the advantages provided by a monobloc structure.

Advantageously the gearmotor (5) comprises (Fig. 3) a structural casing of the gearmotor which is made up of a first shell consisting of a cover (16) and of a second shell consisting of a box (7). The box (7) and cover (16) assembly constitutes the overall shell or casing (25), which encloses both the motor (6) and the gear-reducing device (4) becoming an integral part of the drive. This solution advantageously provides complete access to the inside of the gearmotor (5) because, by removing the cover (16), the gearmotor (5) can be opened very easily into two parts (Fig. 8) with on one side the gear-reducing device (4) with complete access to its elements from inside the vehicle and on the other side the motor (6) which is also completely and easily accessible because it is completely removable from the vehicle by simply unscrewing a series of bolts.

In this way, all the misalignment and engagement problems, which may be encountered during the installation of an external motor, are advantageously avoided. The casing (25) comprises one or more chambers, which can be used as an oil stock and/or as a recirculation channel of the oil itself, if one wants to use all the oil of the gear-reducing device for cooling.

In the solution according to the present invention the driving shaft (8) directly constitutes the first pinion (14) of the first reduction stage of the gearmotor (5) as well. In fact (Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10) the first pinion (14) or pinion of the first reduction stage is directly obtained on the driving shaft (8) of the motor (6) according to a solution in which the driving shaft (8) is mechanically machined to obtain the engagement teeth (20) of the first pinion (14) which are intended to be coupled with the gears (2) of the gear-reducing device (4).

Furthermore, the driving shaft (8) also constitutes the connection for the application of the braking system. In fact, the brake (3) is obtained (Fig. 3) in correspondence of the body of the motor itself on the opposite side with respect to the side of the motor in correspondence of which there are the engagement teeth (20) of the first pinion (14).

As a consequence the driving shaft (8) assumes a threefold function of:

- input gear of the gear-reducing device or first pinion (14);

- actual driving shaft (8);

- connection for the application of the braking system (3).

By this solution one obtains a very compact and inexpensive drive that can reach nearly absolute construction precision limits: by obtaining the input gear of the gear- reducing device, that is to say, the first pinion (14), directly on the driving shaft (8) it is possible to increase reduction ratios with the consequent possibility to increase the rotational speed of the motor (6) thanks to the particularly precise construction. In fact, the solution according to the invention preferably provides the use of motors with high rotational speeds which, when in operation, work for example at speeds of the order of 8000-12000 revolutions per minute. To reduce noise to a level similar to or lower than that of the motors normally used in the prior art, which operate at speeds of the order of 5000 revolutions per minute, it is essential that the precision of the first reduction stage is maximum and that the gear obtained directly on the driving shaft (8) is size ground with maximum precision. In order to be able to obtain a high degree of precision, with the described size grinding of the driving shaft (8) being necessary, the driving shaft must have a diameter smaller than the head diameter of the gear consisting of the teeth (20) of the first pinion (14). This is necessary because it is necessary to guarantee the passage of the size grinding tool.

As a consequence, due to the need for the size grinding operation in order to increase precision, and thus reduce noise, enabling high rotational speeds, the driving shaft (8), in the zone of the head of the gear consisting of the teeth (20) of the first pinion (14), has a diameter smaller than that of the head with the teeth (20), whose diameter, in its turn, cannot be reduced because it is necessary to maintain in any case a given minimum diameter to enable the mechanical machining for obtaining the teeth (20) themselves without weakening the portion of driving shaft (8) that constitutes the first pinion (14).

The adopted solution as to the size grinding of the driving shaft (8) resulted, in its turn, in another problem concerning the presence of a smaller diameter in the zone between the body of the motor and the head of the gear consisting of the teeth (20) of the first pinion (14). In fact, due to the presence of the gear consisting of the teeth (20) of the first pinion ( 4) and having a diameter larger than the diameter of the size ground driving shaft (8), it is not possible to properly support the driving shaft (8) by means of a traditional bearing applied by sliding on the size ground portion. In fact, the internal diameter of the bearing should essentially correspond to the diameter of the size ground portion with the consequence that it could not be fitted on this portion due to the presence of the gear consisting of the teeth (20) of the first pinion (14) that has a larger diameter.

A solution was thus conceived in such a way that the bearing (21) of the first pinion (14) is mounted on the shaft using (Fig. 5, Fig. 6) a bushing (22) made up of two half- shells or half-portions, that is to say, a first half-portion (23) and a second half-portion (24), which, when placed in a proximity condition with respect to each other, constitute a bushing (22) intended to support a corresponding bearing of the first pinion (21), which rotationally supports the first pinion (14) consisting of the driving shaft (8).

Thanks to the solution of the first pinion (14) obtained directly on the size ground driving shaft (8), it is possible to use a high-speed motor (6), this being also made possible by the fact that, thanks to the integration of the motor (6) itself with the gear- reducing device (4), one single body with extremely precise coupling is formed.

Furthermore, in order to enable the use of a high-speed motor it was necessary to study a technical solution to the problem of reducing flexure and/or deformation, which, in addition to the problem of early wear of the components, can give rise to undesirable high-frequency vibrations. In particular it was necessary to study a solution that could allow to minimize the effect of the stresses on the first pinion (14) obtained directly on the size ground driving shaft (8), as will be explained in the following of the present description.

The use of a high-speed motor, for example a motor with maximum speed of the order of 8000-12000 revolutions per minute, provides significant advantages:

- the motor is particularly compact and, as a result, economical and lightweight. For example the solution according to the present invention enables the use of motors having a high rotational speed and particularly compact in such a way that, with respect to a solution with a standard motor, the use of this motor allows to reduce overall dimensions beyond the frame connection flange towards the inside of the machine by 40%. Moreover, as compared to a solution with a standard motor, the use of this motor allows to work with a double maximum input drive speed, that is to say, with a 100% increase, with all the benefits deriving therefrom, as explained in the present description;

- the maximum input torque is approximately halved with respect to the prior art configurations, making it possible to use smaller gears for the gear-reducing device (4); in particular the first pinion (14) of input of the gear-reducing device can be easily made directly on the driving shaft (8);

- the reduction ratio of the gear-reducing device (4) increases in proportion to speed;

- by applying a dynamic service brake (3) or a parking brake, which acts on the driving shaft (8), with equal braking action, the brake (3) will have to develop a low braking torque.

The gearmotor (5) can be designed to use or not to use oil-bath motors, thus providing a system in which the oil of the gear-reducing device recirculates through suitable channels passing, yet without touching the rotor of the motor, to carry out a general cooling of the gearmotor as a whole: in this way there is no need to use sealing gaskets between the motor (6), the gear-reducing device (4) and the brake (3), for the benefit of mechanical efficiency.

As to the operation of the gearmotor (5), a driving wheel is mounted on the respective hub (1 ), which is integrated or anyway made integral (Fig. 3) with the spider (11) of a second reduction stage of the gear-reducing device (4), said second reduction stage being an epicyclic reduction stage. In the embodiment shown the spider (11) is fixed to the hub (1 ) by means of a locknut (13) that is screwed on a corresponding threaded portion protruding from the hub (1 ). Internally and axially to the protrusion comprising the threaded portion, on the hub (1 ) an insertion seat is obtained for sliding and supporting means (19) of the end of the second pinion (15) which is made in the form of one single body with the first crown (17) or crown of the firstreduction stage of the gearmotor. The single body consisting of the second pinion (15) and first crown (17) assembly is supported on the opposite side with respect to the side on which the second pinion (15) is obtained, by means of a respective bearing of the second pinion, which is applied on a cover (16) of the gear-reducing device (4). The single body consisting of the second pinion (15) and first crown (17) assembly is thus rotatably supported by the cover (16) on a first side and by the hub (1) on a second opposite side.

The spider (1 1) in its turn receives the motion by means of the planetary gears (12) of the second reduction stage that in the embodiment shown are three planetary gears that are engaged on the three corresponding insertion seats present on the spider (11) and that are geared on the corresponding second crown (10) or crown of the epicyclic stage, which is stationary and is mounted by means of a respective crown- holding disc (9). The crown-holding disc (9) is screwed on the box (7) of the gear- reducing device (4). The second crown (10) is fixed to the box (7) by a respective fastening ring (9) or crown-holding disc. The planetary gears (12) receive the motion by means of the single body consisting of the second pinion (15) and first crown (17) assembly.

The first toothed crown (17) is geared directly on the first pinion (14) or pinion of the first reduction stage, which, as previously explained, is obtained directly on the shaft (8) of the motor (6) and is supported in correspondence of the cover (16).

All the gears of the gear-reducing device (4) are incorporated in a first chamber (18) or gear-reducing device chamber.

The configuration of a casing (25), made up of the cover (16) and box (7), constituting the container that encloses both the motor (6) and the gear-reducing device (4) also provides complete access to the gearmotor because, by disassembling the casing (25) into its two constituent parts, the gearmotor can be opened very easily into two parts with the gear-reducing device (4) on one side and the motor (6) on the other side. As a consequence, access to the gearmotor is particularly simple and complete in correspondence of all its components with significant advantages in terms of inspection and maintenance.

Advantageously the driving shaft (8), in addition to the previously described functions of driving shaft (8) and first pinion (14) of the gear-reducing device (4), also performs the function of braking shaft because the driving shaft (8) protrudes externally from the body of the motor itself in correspondence of the opposite side with respect to the side on which there is the interface between the motor (6) and the gear-reducing device (4).

The driving shaft (8) is coupled with a corresponding braking system (3) which preferably consists of an electromagnetic brake of the known type.

Without limits for the purposes of the present invention, examples of electric traction vehicles on which the gearmotor (5) according to the present invention can be applied are industrial vehicles, tractors, forklift trucks. Finally, the present invention also relates to an electric traction vehicle, which comprises at least one gearmotor (5) according to the present invention for direct drive to the driving wheel of the electric traction vehicle.

To conclude, the present invention relates (Fig. 3) to a gearmotor (5) for direct drive to a driving wheel of an electric traction vehicle, wherein a traction motor (6), provided with respective driving shaft (8) protruding with respect to a body of the traction motor (6), is integrated with a gear-reducing device (4) comprising gears, which is connectable to the driving wheel in correspondence of a hub (1 ). The gear- reducing device (4) is housed in a structural supporting box (7) suitable to be fixed to the electric traction vehicle constituting a body of the gear-reducing device. The box (7) defines at least one first chamber (18) or gear-reducing device chamber. The traction motor (6) has its own supporting shell constituting a body of the motor, which is fixed as a cover (16) to the box (7), the box (7) and the cover (16) constituting one single structural supporting casing (25) of the gearmotor (5). The cover (16) covers and encloses the gear-reducing device (4) within the box (7) and the removal (Fig. 8) of the cover (16) provides free access to the gear-reducing device (4) on one side and to the motor (6) on the opposite side. The motor (6) is coupled (Fig. 3, Fig. 4) with the gear-reducing device (4) by means of a first coupling end (27) of the driving shaft (8), which constitutes the first pinion (14) of the gear-reducing device (4), the coupling between the motor (6) and the gear-reducing device (4) occurring without the interposition of further transmission elements obtaining a direct coupling between the motor (6) and the gear-reducing device (4) in which the transmission shaft of the motor (6) is directly coupled with a first crown (17) of the gears of the gear-reducing device (4).

The driving shaft (8) is mechanically machined (Fig. 9, Fig. 10) in correspondence of the first coupling end (27) with the first crown (17) obtaining engagement teeth (20) of the first pinion (14), which are intended to be coupled with corresponding counter- teeth of the first crown (17). Furthermore (Fig. 9, Fig. 10) the driving shaft (8) is mechanically machined in correspondence of an intermediate zone between the teeth and the body of the motor (6) in such a way as to obtain an insertion seat (26) having a diameter smaller than the diameter of the first coupling end (27) provided with engagement teeth (20).

As previously explained, the adopted solution, by the combination of high-speed motor and first pinion (14) obtained directly on the driving shaft (8), made it necessary to search for a solution enabling the reduction in the flexure and/or deformation due to radial load, which may give rise to undesirable high-frequency vibrations, in particular with reference to the stresses on the first pinion (14).

To this purpose, the gearmotor (5) comprises a supporting bearing (21 ) of the driving shaft (8) which is engaged on the driving shaft (8) in correspondence of the seat (26) by means of a bushing (22) made up of at least two portions (23, 24), of which at least one first portion (23) and at least one second portion (24) which, when placed in a proximity condition with respect to each other, form a bushing (22) intended to support the bearing (21), which in its turn rotationally supports the first pinion (14) consisting of the driving shaft (8). Preferably the bushing (22) is made up of only two of said portions (23, 24). For example the bushing (22) can be made up of only two of said portions (23, 24), which are identical to each other. For example the bushing (22) can be made up of only two of said portions (23, 24), which are symmetrical to each other. For example the bushing (22) can be made up of only two of said portions (23, 24), which are provided with interlocking means. The bushing (22) has an external diameter greater than the diameter of the first coupling end (27) provided with engagement teeth (20) in such a way that the bearing (21 ) can be inserted and extracted by sliding into an insertion condition in which the first coupling end (27) provided with engagement teeth (20) passes through the bearing (21).

In less preferred solutions of the present invention it is also possible to use a bushing (22) made up of a number of portions (23, 24) greater than two, such as three portions that can be adjoined to or assembled with each other within the seat in such a way as to obtain an increase in the diameter so as to obtain the supporting function of the bearing (21).

Thanks to the solution of the bushing (22) made up of at least two portions (23, 24), preferably in the form of a first portion (23) constituting a first half-bushing and a second portion (24) constituting a second half-bushing, it is possible to mount the bearing (21) at a very small distance with respect to the toothed part (20), thus minimizing the levering action of the radial forces present in correspondence of the pinion (20) and crown (17) coupling and thus minimizing deformation or flexure and thus the possibility of "wobbling" at high speed, which is the cause of potential vibrations induced at high frequency. Advantageously, by the solution according to the present invention, it is possible to obtain a reduction (Fig. 4) in the distance (D) between the bearing (21) and the first coupling end (27) provided with engagement teeth (20) of the driving shaft (8). Said considerable advantage is obtained in particular, thanks to the combination of characteristics of:

- first pinion (14) obtained directly on the driving shaft (8); - seat (26) obtained on the first pinion, wherein the seat has a diameter smaller than the diameter of the first coupling end (27) provided with engagement teeth (20);

- bushing (22) of engagement for the supporting bearing (21 ) of the driving shaft (8) made up of at least two portions (23, 24).

Thanks to the described solution it is possible to obtain a reduction in the distance (D) between the bearing (21) and the first coupling end (27) provided with teeth (20). In particular by the described solution it is possible to advantageously obtain a distance (D) between the bearing (21) and the first coupling end (27) of less than 15 mm. Particularly, in an advantageous solution the distance (D) between the bearing (21) and the first coupling end (27) is of less than 10 mm. In the preferred solution of the present invention the distance (D) between the bearing (21 ) and the first coupling end (27) is between 0 mm and 6 mm. In general the preferred solution provides a distance (D) between the bearing (21 ) and the first coupling end (27) of less than 5 mm, the most preferred value being the lowest value attainable.

Configurations without the described solution cannot have values of the distance (D) between the bearing (21) and the first coupling end (27) of, less than 20 mm. This means that a shorter driving shaft (8) can be used, reducing or even cancelling the effect of possible flexure and/or deformation of the driving shaft (8) itself. Furthermore, the reduced distance (D) is equivalent to a reduction in the length of the motion transmission arm, thus also contributing to reducing the amplitude of any vibrations present or generated. As a result, considering the reduction in the vibrations and twists, it is possible to reach lower working tolerances obtaining a much more precise coupling between the driving shaft (8) and the first crown (17) or crown of the first reduction stage.

The first crown (17) of the gears of the gear-reducing device (4) is integrated (Fig. 3) with a second pinion ( 5) of the gears according to a configuration in which the first crown (17) and the second pinion (15) form one single body. The driving shaft (8) comprises in correspondence of a second end (28), which is an opposite end of the driving shaft (8) with respect to the first end (27), coupling means for the coupling with a braking system (3), the driving shaft thus constituting:

i) the actual driving shaft of the motor (6);

ii) one of the input gears of the gear-reducing device (4) having the function of first pinion (14);

iii) a connection for the application of the braking system (3).

The braking system (3) is made in the form of a brake of the electromagnetic type. The body of said motor (6) is arranged in an essentially misaligned position with respect to the body of the gear-reducing device (4) and is suitable to be positioned in an essentially upper position with respect to the position of said gear-reducing device (4) when the gearmotor (5) is mounted on the vehicle, the term upper referring to the ground when the gearmotor (51) is mounted on the vehicle.

The present invention also relates to an electric traction vehicle, which comprises at least one gearmotor (5) for direct drive to a driving wheel of the electric traction vehicle, wherein the gearmotor (5) is a gearmotor having the previously described characteristics.

The description of the present invention has been made with reference to the enclosed figures in a preferred embodiment, but it is evident that many possible changes, modifications and variations will be immediately clear to those skilled in the art in the light of the previous description. Thus, it must be underlined that the invention is not limited to the previous description, but it includes all the changes, modifications and variations in accordance with the appended claims. Nomenclature used

With reference to the identification numbers in the enclosed figures, the following nomenclature has been used:

1. Wheel hub 2. Gears

3. Brake or braking system

4. Gear-reducing device

5. Gearmotor

6. Motor

7. Box

8. Driving shaft

9. Crown-holding disc

10. Second crown or crown of the epicyclic stage 11. Spider

12. Planetary gear

13. Locknut

14. First pinion or pinion of the first reduction stage

15. Second pinion or pinion of the epicyclic stage 16. Supporting shell or cover

17. First crown or crown of the first reduction stage

18. First chamber or gear-reducing device chamber

19. Sliding and supporting means

20. Teeth

21. Bearing of the first pinion

22. Bushing

23. First half-portion or first portion

24. Second half-portion or second portion

25. Casing

26. Seat

27. First end

28. Second end

Claims

1. Gearmotor (5) for direct drive to a driving wheel of an electric traction vehicle wherein a traction motor (6), provided with a respective driving shaft (8) protruding with respect to a body of the traction motor (6), is integrated with a gear-reducing device (4) comprising gears, which is connectable to the driving wheel in correspondence of a hub (1), wherein the gear-reducing device (4) is housed in a structural supporting box (7) suitable to be fixed on the electric traction vehicle constituting a body of the gear-reducing device, the box (7) defining at least one first chamber (18) or gear-reducing device chamber, the traction motor (6) having its own supporting shell constituting a body of the motor, which is fixed as a cover (16) to the box (7), the box (7) and the cover (16) constituting one single structural supporting casing (25) of the gearmotor (5), the cover (16) covering and enclosing the gear- reducing device (4) within the box (7), the removal of the cover (16) providing free access to the gear-reducing device (4) on one side and to the motor (6) on the opposite side, wherein the motor (6) is coupled with the gear-reducing device (4) by means of a first coupling end (27) of the driving shaft (8) which constitutes the first pinion (14) of the gear-reducing device (4), the coupling between the motor (6) and the gear-reducing device (4) occurring without the interposition of further transmission elements obtaining a direct coupling between the motor (6) and the gear-reducing device (4) wherein the transmission shaft of the motor (6) is directly coupled with a first crown (17) of the gears of the gear-reducing device (4), characterised in that the driving shaft (8) is mechanically machined in correspondence of said first coupling end (27) with the first crown (17) obtaining engagement teeth (20) of the first pinion (14) intended to be coupled with corresponding counter-teeth of the first crown (17), the driving shaft (8) being further mechanically machined in correspondence of an intermediate zone between the teeth (20) and the body of the motor (6) in such a way as to obtain an insertion seat (26) having a diameter smaller than the diameter of said first coupling end (27) provided with engagement teeth (20) and further characterised in that the gearmotor (5) comprises a supporting bearing (21 ) of the driving shaft (8) which is engaged on the driving shaft (8) in correspondence of the seat (26) by means of a bushing (22) which is made up of at least two portions (23, 24), of which at least one first portion (23) and at least one second portion (24) which, when placed in a proximity condition with respect to each other, form a bushing (22) intended to support the bearing (21 ), which in its turn rotationally supports the first pinion (14) consisting of the driving shaft (8).

2. Gearmotor (5) for direct drive to a driving wheel of an electric traction vehicle according to the previous claim, characterised in that the bushing (22) is made up of only two of said portions (23, 24).

3. Gearmotor (5) for direct drive to a driving wheel of an electric traction vehicle according to any of the previous claims, characterised in that between the bearing (21) and the first coupling end (27) provided with engagement teeth (20) of the driving shaft (8) there is a distance (D) of less than 15 mm.

4. Gearmotor (5) for direct drive to a driving wheel of an electric traction vehicle according to the previous claim, characterised in that the distance (D) is of less than 10 mm.

5. Gearmotor (5) for direct drive to a driving wheel of an electric traction vehicle according to the previous claim, characterised in that the distance (D) is of less than

5 mm.

6. Gearmotor (5) for direct drive to a driving wheel of an electric traction vehicle according to any of the previous claims, characterised in that the bushing (22) has an external diameter greater than the diameter of said first coupling end (27) provided with said engagement teeth (20) in such a way that the bearing (21) can be inserted and extracted by sliding into an insertion condition in which the first coupling end (27) provided with said engagement teeth (20) passes through the bearing (21 ).

7. Gearmotor (5) for direct drive to a driving wheel of an electric traction vehicle according to any of the previous claims, characterised in that the first crown (17) of the gears of the gear-reducing device (4) is integrated with a second pinion (15) of said gears according to a configuration in which the first crown (17) and the second pinion (15) form one single body.

8. Gearmotor (5) for direct drive to a driving wheel of an electric traction vehicle according to any of the previous claims, characterised in that said driving shaft (8) comprises, in correspondence of a second end (28), which is an opposite end of the driving shaft (8) with respect to said first end (27), coupling means for the coupling with a braking system (3), the driving shaft thus constituting:

i) the driving shaft of the motor (6);

iii) a connection for the application of the braking system (3).

9. Gearmotor (5) for direct drive to a driving wheel of an electric traction vehicle according to the previous claim, characterised in that the braking system (3) is a brake of the electromagnetic type.

10. Gearmotor (5) for direct drive to a driving wheel of an electric traction vehicle according to any of the previous claims, characterised in that the motor (6) is a high- speed motor with maximum rotational speed of the order of 8000-12000 RPM.

11. Gearmotor (5) for direct drive to a driving wheel of an electric traction vehicle according to any of the previous claims, characterised in that the body of the motor (6) is arranged in an essentially misaligned position with respect to the body of the gear-reducing device (4) and is suitable to be positioned in an essentially upper position with respect to the position of said gear-reducing device (4) when said gearmotor (5) is mounted on the vehicle, the term "upper" referring to the ground when said gearmotor (51) is mounted on said vehicle.

12. Electric traction vehicle characterised in that it comprises at least one gearmotor (5) according to any of the previous claims for direct drive to a driving wheel of said electric traction vehicle.