ELECTRIC AGRICULTURAL TRACTOR WITH A COMPACT REAR AXLE

Abstract

ELECTRIC AGRICULTURAL TRACTOR COMPRISING A COMPACT REAR AXLE The invention relates to an electric agricultural tractor comprising: a rear axle (100) comprising at least one rear axle (110), at least two wheels (140a, 140b), a main housing (200), a central housing (120), and a power take-off (130) arranged in said central housing (120); an electric power take-off motor (150), arranged on the housing (200) and extending longitudinally, said motor (150) comprising an output shaft configured to drive said power take-off (130) in rotation; an electric traction motor (160), arranged on the housing (200) and extending transversely, said motor (160) comprising an output shaft configured to drive each wheel (140a, 140b) in rotation. Figure for the summary: Figure 1

Description

Title of the invention: ELECTRIC AGRICULTURAL TRACTOR COMPRISING A COMPACT REAR AXLE Technical field of the invention

[0001] The invention relates to a rear axle system for an electric agricultural tractor. More particularly, the invention relates to an electric agricultural tractor comprising a rear axle system whose architecture has been redesigned to accommodate a large-capacity power supply battery. Technological background

[0002] In an agricultural context where fieldwork has been greatly facilitated by the development of agricultural machinery, the use of thermal agricultural tractors, widely favored by farmers, will now have to face the challenge of the ecological transition.

[0003] Some agricultural concepts have been developed around a more restricted, fully electric operation.

[0004] The energy demand of a fully electric agricultural tractor remains a limiting factor and the proposed batteries pose a real challenge for the structure of these vehicles.

[0005] Most of the proposed electrification systems include additional structures added to the conventional architecture of a tractor. These structures have the disadvantage of increasing the vehicle's weight, but they can also complicate the arrangement of the tractor's mechanical or hydraulic components.

[0006] The electrification of agricultural tractors does not allow for a significant break with the traditional structure of thermal tractors while allowing for the arrangement of a battery offering the best compromise between operating autonomy and tractor size.

[0007] An electric agricultural machine must be able to accommodate a large-capacity, large-volume battery to achieve satisfactory operating range. However, adjustments in terms of weight and equipment are necessary to compensate for the installation of this large battery, as the conventional layout of the tractor's components does not allow for optimizing the space required for a large battery. Furthermore, the agricultural tractor must comply with specific and strict regulatory constraints that prevent the chassis from being extended at will, in addition to constraints related to maneuverability and vehicle height. Therefore, the large-volume battery configuration must not compromise the compactness of the agricultural vehicle.

[0008] In addition, previous solutions in most cases retain the transmission shafts between the gearbox, the power take-off (commonly called PTO, for Power Take-Off), the front axle, the rear axle and the gearbox housings which are load-bearing and bulky elements of the central space of the tractor.

[0009] Conventionally, known agricultural tractors have a configuration in which an engine is longitudinally connected to a gearbox. These tractors include a main drive shaft connected to a differential, which is configured to transmit engine torque to the axle and ultimately to the wheels. Regarding the power take-off (PTO), the engine drives a secondary drive shaft, allowing the transmission of engine torque to the PTO from the same engine.

[0010] This configuration is bulky and not suitable for making the best use of the longitudinal space of the chassis. Furthermore, such a configuration is not optimized for the compactness of the tractor's rear axle. In particular, such a configuration is incompatible with the need for a large battery in the central part of the chassis.

[0011] There is therefore a need to provide a fully electric agricultural tractor capable of overcoming the previous problems. Objectives of the invention

[0012] The invention also aims to provide, in at least one embodiment, an electric tractor comprising a compact rear axle optimized for the integration of a large volume battery.

[0013] The invention also aims to provide, in at least one embodiment, an electric tractor with direct electric transmission.

[0014] The invention aims to provide, in at least one embodiment, an electric agricultural tractor comprising a rear axle configured to transmit independent engine torque to the power take-off and traction.

[0015] The invention also aims to provide, in at least one embodiment, an electric agricultural tractor with a structure allowing simplified mounting of a long-range electric battery. Description of the invention

[0016] To this end, the invention relates to an electric agricultural tractor comprising a chassis extending mainly in a longitudinal direction, characterized in that said electric agricultural tractor further comprises: - a rear axle comprising at least one rear axle arranged in a transverse direction substantially perpendicular to the longitudinal direction, at least two wheels mounted on each rear axle, a main casing, a central housing, and a power take-off arranged in said central housing; - a first electric motor, called the power take-off motor, arranged on the main casing in a direction parallel to the longitudinal direction of the tractor and comprising an output shaft extending in said direction parallel to the longitudinal direction and configured to drive said power take-off in rotation; - a second electric motor, called the traction motor, arranged on the main casing in a direction parallel to the transverse direction of the tractor and comprising an output shaft extending in said direction parallel to the transverse direction and configured to drive each wheel in rotation.

[0017] An electric agricultural tractor according to the invention thus benefits from a compact rear axle, leaving ample space for integrating a large-volume, and therefore high-capacity, battery on the chassis in a central position. Furthermore, the orthogonal configuration of the two motors on the main housing of the rear axle eliminates the need for an extensive mechanical drivetrain. This contributes to obtaining a large central volume, ideal for installing a high-capacity battery pack within the electric tractor.

[0018] According to a first variant of the invention, the tractor includes a gearbox, called a power take-off gearbox, arranged at least in part in said central housing and comprising transmission wheels whose axes of rotation extend mainly in a direction parallel to the longitudinal direction of said tractor, said gearbox mechanically connecting said first electric motor to said power take-off.

[0019] Thus and according to this first variant, the transverse bulk of the rear bridge is reduced which makes it possible to optimize the space available for a high capacity battery pack.

[0020] According to a second embodiment of the invention, the tractor includes a gearbox, called a traction gearbox, comprising transmission wheels whose axes of rotation extend mainly in a direction parallel to the transverse direction of said tractor, said gearbox mechanically connecting said second electric motor to a traction torque transmission system at each wheel.

[0021] Thus and according to this second variant, the longitudinal bulk of the rear axle is reduced, which makes it possible to optimize the space available for a high-capacity battery pack.

[0022] The electric agricultural tractor also allows independent control of the rear traction and the power take-off through the use of two independent motor-gearbox assemblies, a traction assembly arranged substantially transversely and a power take-off assembly arranged substantially longitudinally.

[0023] The power take-off assembly benefits from an advantageous position thanks to partial integration into the central housing.

[0024] Advantageously and according to the invention, the tractor includes at least one electronic control unit configured to adjust the torque of the power take-off motor and the torque of the traction motor.

[0025] According to this aspect of the invention, a central electronic control unit controls the two electric motors.

[0026] Advantageously and according to the invention, the traction torque transmission system includes a differential configured to distribute the traction torque applied to each wheel of each rear axle.

[0027] According to this aspect of the invention, the differential allows differential and independent control of the two wheels of the rear axle.

[0028] Advantageously and according to the invention, the electric agricultural tractor includes a steering system comprising tie rods connected to hydraulic cylinders and steerable hubs, arranged between the power take-off gearbox and the traction torque transmission system.

[0029] According to this aspect of the invention, the rear axle includes its own steering system which makes it possible to increase the turning radius of the electric agricultural tractor, because the front turning radius is sometimes limited by the presence of large volume and therefore large capacity batteries.

[0030] Advantageously and according to the invention, the power take-off motor is configured to drive at least one hydraulic pump.

[0031] According to this aspect of the invention, the hydraulic pump is advantageously driven by the same motor as the power take-off, resulting in a more compact system. The hydraulic pump can, for example, be selected from hydraulic or electronic load-sensing pumps.

[0032] According to a preferred embodiment, said hydraulic pump is an electronically load-sensing hydraulic pump.

[0033] According to this preferred embodiment, it becomes possible to adjust the flow rate at the pump outlet according to hydraulic requirements, which improves the energy efficiency of the hydraulic system and limits pressure losses.

[0034] According to one embodiment of the invention, the power take-off motor is configured to drive two hydraulic pumps.

[0035] Thus and according to this variant, the hydraulic management of the rear axle is centralized around the power take-off motor, which allows for a compact assembly that is advantageous for the integration of a large volume battery.

[0036] Advantageously, the tractor further includes a hydraulic control unit configured to control at least one hydraulic pump.

[0037] When the pump has electronic load sensing, the control unit allows the hydraulic control to be adapted according to the tool attached to the tractor at the power take-off, which optimizes hydraulic management according to the needs.

[0038] According to a preferred embodiment, the central housing and the power take-off motor are arranged in the upper part of the rear axle, above at least one rear axle.

[0039] This preferred variant frees up space under the rear axle, allowing the battery to be integrated into a low, central area of ​​the tractor. Advantageously, when the power take-off gearbox is arranged at least partially in said central housing, the overall footprint of the power take-off function is particularly optimized. List of figures

[0040] Other objects, features and advantages of the invention will become apparent from the following description, given by way of non-limiting example only, and which refers to the accompanying figures in which: • [Fig. 1] shows a partial top view of an electric agricultural tractor according to one embodiment of the invention, • [Fig.2] schematically and partially represents a cross-section of the electric agricultural tractor according to one embodiment of the invention, • [Fig.3] schematically illustrates a configuration of the electronic and hydraulic control of the tractor according to an embodiment of the invention.

[0041] Detailed description of an embodiment of the invention

[0042] In the figures, the scales and proportions are not strictly respected for the purposes of illustration and clarity.

[0043] Identical, similar or analogous elements are designated by the same reference numerals in all figures.

[0044] In all the detailed description that follows with reference to the figures, unless otherwise indicated, each element is described as it is arranged in an electric agricultural tractor.

[0045] Figures 1 and 2 schematically represent a 300 electric agricultural tractor, respectively from above and in side section, according to an embodiment of the invention. The representations are partial in that the rear part of the electric agricultural tractor is visible, in particular the rear axle 100.

[0046] The rear bridge 100 includes a rear axle 110 (comprising two parts 110a, 110b, connected by a differential 112), a main housing 200.

[0047] The rear axle includes a power take-off assembly comprising a power take-off motor 150 and a power take-off gearbox 152, arranged in the longitudinal direction (i.e., the left-to-right direction for Figures 1 and 2). The power take-off motor 150 can also drive a hydraulic pump 180.

[0048] The rear axle includes a traction assembly comprising a traction motor 160 and a traction speed gearbox 162, arranged in the transverse direction (i.e. the top-down direction for [Fig.1] and the direction perpendicular to the plane shown in [Fig.2], for example the direction shown by the point showing axle 110).

[0049] A steering system 190 allows the rear wheels 140a, 140b to be turned.

[0050] Thanks to the orthogonal arrangement of the power take-off motor 150, the traction motor 160, their respective gearboxes 152 and 162 and the steering system 190, the rear axle 100 has a particularly compact architecture.

[0051] This allows the integration of a large 400 battery.

[0052] In addition, a central volume in the lower area of ​​the tractor can still be advantageously optimized to accommodate a large 400 battery, when the tractor has a hydraulic pump driven by the engine and 150 power take-off and when the central housing 120 and the 150 power take-off motor are arranged in the upper part of the rear axle 100, above at least one rear axle of the tractor.

[0053] Fig. 3 schematically illustrates the architecture of the tractor's electronic and hydraulic control system according to one embodiment of the invention.

[0054] The electronic control unit 500 is configured to adjust the torque of the traction motor 160 and the power take-off motor 150. The power take-off motor 150 drives two load-sensing hydraulic pumps 510, the output flow of which is controlled by a hydraulic control unit 520.

[0055] This tractor architecture thus helps to maintain a particularly compact rear axle while ensuring efficient and adaptable hydraulic management.

Claims

Demands

1. Electric agricultural tractor comprising a chassis extending mainly in a longitudinal direction characterized in that said electric agricultural tractor further comprises: • a rear axle (100) comprising at least one rear axle (110) arranged in a transverse direction substantially perpendicular to the longitudinal direction, at least two wheels (140a, 140b) mounted on each rear axle (110), a main housing (200), a central housing (120), and a power take-off (130) arranged in said central housing (120); • a first electric motor, referred to as the power take-off motor (150), arranged on the main housing (200) in a direction parallel to the longitudinal direction of the tractor and comprising an output shaft extending in said direction parallel to the longitudinal direction and configured to drive said power take-off (130) in rotation;• a second electric motor, called the traction motor (160), arranged on the main casing (200) in a direction parallel to the transverse direction of the tractor and comprising an output shaft extending in said direction parallel to the transverse direction and configured to drive each wheel (140a, 140b) in rotation.

2. Tractor according to claim 1, characterized in that it comprises a gearbox, said power take-off gearbox (152), arranged at least in part in said central housing (120) and comprising drive wheels whose axes of rotation extend mainly in a direction parallel to the longitudinal direction of said tractor, said gearbox (152) mechanically connecting said first electric motor (150) to said power take-off (130).

3. Tractor according to claim 2, characterized in that it comprises a gearbox, said traction speed gearbox (162), comprising transmission wheels whose axes of rotation extend mainly in a direction parallel to the transverse direction of said tractor, said gearbox (162) mechanically connecting said second electric motor (160) to a traction torque transmission system at each wheel (140a, 140b).

4. Electric agricultural tractor according to claim 3, characterized in that the traction torque transmission system includes a differential (112) configured to distribute the traction torque applied to each wheel of each rear axle.

5. Electric agricultural tractor according to any one of claims 2 to 4, characterized in that it comprises a steering system (190) including tie rods connected to hydraulic cylinders and steerable hubs, arranged between the power take-off gearbox (152) and the traction torque transmission system.

6. Electric agricultural tractor according to any one of the preceding claims, characterized in that it comprises at least one electronic control unit (500) configured to adjust the torque of the power take-off motor (150) and the torque of the traction motor (160).

7. Electric agricultural tractor according to any one of the preceding claims, characterized in that the power take-off motor (150) is configured to drive at least one hydraulic pump (510).

8. Electric agricultural tractor according to claim 7, characterized in that said hydraulic pump (510) is an electronically load-sensing hydraulic pump.

9. Electric agricultural tractor according to any one of claims 7 to 8, characterized in that the power take-off motor (150) is configured to drive two hydraulic pumps (510).

10. Electric agricultural tractor according to any one of claims 7 to 9, characterized in that it further comprises a hydraulic control unit (520) configured to control at least one hydraulic pump (510).

11. Electric agricultural tractor according to any one of the preceding claims, characterized in that central housing (120) and power take-off motor (150) are arranged in the upper part of the rear deck (100), above at least one rear axle.

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