Electrical system for series hybrid agricultural vehicles

Abstract

The invention relates to an electrical system for a series hybrid agricultural vehicle (15, 20) comprising a steerable front drive axle (13, 19), with wheels (1) on the right and left extremities, and a rear drive axle (14) with wheels (2) on the right and left extremities, wherein said electrical system comprises at least one electric generator set (16) formed by a combustion engine (8) connected to a motor / generator (9) to transfer energy to at least one invertor (5) connected to an electrical connection box (6) that distributes energy to electric drive units (EDU) composed of reduction gears (4) with a neutral position (18), an electric motor (17) and an invertor (5), wherein the front axle (13, 19) and the rear axle (4) are connected to EDUs (4, 17, 5) for driving the front wheels (1) and rear wheels (2). The energy produced by the motor / generator (9) connected to the shaft of the combustion engine (8) is consumed by the electric motor (17) connected to the front (13) and rear (14) drive axles.

Description

ELECTRICAL SYSTEM FOR HYBRID AGRICULTURAL VEHICLES SERIES Field of Invention

[0001] This patent application falls within the fields of engineering and agriculture. More specifically, this invention relates to an electrical system for hybrid agricultural vehicles, that is, vehicles that use both electrical energy and energy generated by a combustion engine. Background of the Invention

[0002] Agricultural vehicles, especially agricultural tractors, traditionally have a combustion engine that provides mechanical energy in the form of torque to one or more wheels in order to propel the vehicle against the ground. These vehicles can also provide energy in different forms to auxiliary systems or attached implements. A traditional form of implement drive is the mechanical power take-off shaft, which provides torque from the engine to a shaft coupled to the implement. This construction uses transmissions, clutches, differentials, and other components to direct the mechanical energy from the engine to the element to be driven, such as a wheel or attached implement.

[0003] Ideally, an internal combustion engine should maintain a specific engine speed that maximizes torque, power, or energy efficiency. Frequently, however, this speed does not correspond to the speed required for the wheels or power take-off shaft. As a result, the engine speed undergoes many changes, leading to increased fuel consumption and emissions.

[0004] In a single tractor, a plurality of components are activated, each with its ideal rotation speed. The transmission components are responsible for transforming the rotation and distributing torque throughout the vehicle. These components are complex, heavy, require intensive maintenance, and are sources of inefficiency due to friction. In addition to the loss of efficiency due to the mechanical transmission components, the operation of the... The engine cannot be easily adjusted based solely on energy efficiency.

[0005] Energy density, durability, and cost are obstacles to the adoption and development of a purely electric heavy vehicle. Heavy vehicles such as heavy machinery and tractors operate with high energy consumption and would require large batteries for storage, which entails high manufacturing and maintenance costs. Hybrid vehicles seek to reduce cost and energy density problems by reducing battery size through the production of electrical or mechanical energy using a combustion engine.

[0006] A parallel hybrid vehicle is constructed so that the combustion engine is mechanically coupled to the drive axle. Thus, the energy expended for its movement can originate exclusively from the combustion engine or the electric motor, or a combination thereof. A series hybrid vehicle, on the other hand, converts mechanical energy into electrical energy on the generator axle and vice versa on the drive axle, separately. In this model, there is no mechanical link between the generator and drive axles, allowing each motor to be controlled independently.

[0007] Regenerative braking is a feature frequently found in electric and hybrid vehicles, allowing the wheel's movement to generate energy to charge the battery, resisting and braking the axle while storing its energy. This function stems from a characteristic of the electric motor that allows it to function as a motor producing mechanical rotation when supplied with electrical energy, or conversely, as a generator producing electrical energy when supplied with mechanical rotation. For this to occur efficiently and safely, this process must be controlled by an enabled controller capable of processing the energy.

[0008] However, the feature of the electric motor that allows regenerative braking is also responsible for a risk for electric vehicles when being towed. It is common for these vehicles to have speed restrictions or The distance required for towing depends on the need to dissipate the energy generated by the wheel axle in contact with the ground. In a malfunction situation, and in the absence of an active controller, the generated energy can overheat and damage the components, creating a safety risk.

[0009] Patent WO-2007 / 031396 presents a propulsion system for an agricultural tractor in which an internal combustion engine drives an electric generator. The energy captured by the generator is used in a plurality of motors to propel the vehicle. The energy produced can be supplied to implements directly or in the form of torque through motors.

[0010] US patent 9637000B2 presents an improvement to the previously mentioned patent, featuring a system capable of regenerative braking through the use of batteries and motor controllers with this capability.

[0011] However, there is still a need to find a system that optimizes the operation of a vehicle's electrical system, reducing maintenance and production costs. Summary of the Invention Patent

[0012] It is an object of the present invention to improve a series of electric-hybrid tractor systems that, in addition to solving the difficulties presented in the prior art and being battery-free, is capable of regenerative braking, electronic torque vectoring, and safe towing. The improvements described below make the hybrid tractor system more economical to produce and maintain in continuous use in the field.

[0013] In the battery-free hybrid electric tractor system described in this document, the mechanical energy produced by a combustion engine is converted into electricity by one or more electric generators and immediately consumed by one or more electric motors, providing torque to the wheels and auxiliary systems. Brief Description of the Figures

[0014] For better understanding and by way of example, the system of The invention is schematically shown in the attached figures in relation to an agricultural tractor.

[0015] Figure 1 is a schematic view of the electrical system of the invention for an agricultural tractor, in which the front axle is a conventional axle with a central mechanical differential.

[0016] Figure 2 is a schematic view of the electrical system of the invention for an agricultural tractor, in which the front axle is an axle with an electronic differential, with torque vectoring.

[0017] The figures are schematic drawings of an agricultural tractor comprising the electrical systems of the invention. Detailed Description of the Invention

[0018] The present invention describes hybrid tractors (15) and (20), which comprise different methods of driving the front axle (13) and (19), respectively.

[0019] The hybrid tractor (15) comprises a conventional, steerable and drive front axle (13), with wheels (1) at the right and left ends, with a central mechanical differential (12) which, proportionally to the steering movement, distributes the mechanical force passing through a cardan shaft (3).

[0020] The mechanical force provided to the cardan shaft (3) comes from the transformation of electrical energy made by a single EDU (Electric Motor Unit) module composed of a controller (5), a motor (17), and a set of reduction gears (4) with neutral position (18).

[0021] The hybrid tractor (20) comprises a steerable and driveable front axle (19), with wheels (1) at the right and left ends, without a central mechanical differential, which is replaced by an electronic differential with torque vectoring, and which independently controls the drive of each front wheel (1) through an independent EDU module (4, 5 and 17). Each front axle, in addition to its respective EDU (4, 5 and 17) and a wheel (1), also includes an additional set of reduction gears (10) and a set of service and parking brakes actuated by electro / hydraulic mechanisms (11).

[0022] Analogously to the front axle (13) or (19), there is a rear axle (14) also electrified, i.e., with electric drive and no direct mechanical connection to the combustion engine (8). The rear axle (14), unlike the front axle (13), but similar to the front axle (19), does not have a central mechanical differential, which is replaced by an electronic differential, with torque vectoring, and which independently controls the drive of each rear wheel (2) through an independent EDU module (4, 5 and 17). Each rear half-shaft, in addition to its respective EDU (4, 5 and 17) and a wheel (2), also includes an additional set of reduction gears (10) and a set of service and parking brakes actuated / controlled by electro / hydraulic mechanisms (11).

[0023] The electrical energy supplied to the EDU modules (4, 5 and 17) for the production of mechanical force comes from a generator set (16), consisting of an internal combustion engine (8) coupled to an electric motor / generator machine (9) and its controller (5), which is connected to an electrical connection box (6) that interconnects it with all the other controllers (5) of each EDU (4, 5 and 17) and also to another electrical connection box (7), which is intended for an external connection to the machine, enabling the electrification of implements that may be towed by the tractor (15 or 20) (not shown), both in terms of traction and functions commonly performed by hydraulic or pneumatic drives.

[0024] The electrical connection box (6) distributes the vehicle's energy to the generating and consuming units (16) and EDU (4, 5 and 17) whose controllers must adhere to the established frequency, voltage and current standards. By using a motor controller capable of acting as both a consumer and generator (5), it is possible to offer regenerative braking to the system, in which the reaction force between the ground and the wheels (1, 2) is transferred to the motors (17) and their controllers (5) which transform it into electrical energy. For To consume the extra energy generated and maintain the system's balance, the generator controller (5) is also capable of operating in reverse. By acting as an engine brake, the generator (9) dissipates energy by reacting against the combustion engine (8), avoiding the need to store electrical energy.

[0025] During operation, the total system energy must be carefully monitored to avoid overloading the components or the junction box and its circuits. This control is performed automatically, with no direct operator intervention in the combustion engine speed or energy generation during operation, including during braking.

[0026] The two tractors (15) and (20) presented have the advantage of fully exploiting the characteristics of electric motors and precisely and individually controlling the speeds of each wheel or axle. The ability to direct torque and control individual rotation allows the use of an electronic differential, with torque vectoring on each wheel. This functionality allows greater vehicle control in maneuvers and greater traction on adverse terrain and conditions.

[0027] In the two tractors (15) and (20) presented, the EDUs (4, 5 and 17) are equipped with a mechanism in their reduction gearboxes (4) that allows the decoupling of the wheel half-shaft from the electric motor (17). This neutral position (18) aims to allow the safe towing of the vehicle without the production of electrical energy or restriction of distance or speed. This functionality is essential for the safe removal or transport of vehicles in a breakdown situation.

[0028] In the two tractors (15) and (20) presented, each independent half-shaft of the EDUs is equipped with an additional set of reduction gears (10). The gears transmit the force produced in the half-shaft, reducing the rotation to the appropriate speed for these wheels.

[0029] In the two tractors (15) and (20) presented, each independent half-shaft of the EDUs is equipped with a set of auxiliary brakes and parking brakes (11). The auxiliary brakes perform the braking of the vehicle in The parking brakes are used when regenerative braking is unavailable or insufficient, while the parking brakes immobilize the vehicle when it is inactive. Both types of brakes are activated and controlled by electro-hydraulic devices.

[0030] Notwithstanding the versions presented, their characteristics can be combined, such as, for example, the shared use of an Electric Drive Unit (EDU) on the rear axle or the presence of additional reductions or a braking system on only one wheel or axle.

Claims

CLAIMS 1. Electrical system for a series hybrid agricultural vehicle (15) comprising a front axle (13), steerable and traction, with wheelsets (1) at the right and left ends, with a central mechanical differential (12), which distributes the mechanical force passing through a cardan shaft (3) to the wheelsets (1), and a rear axle (14) traction with wheelsets (2) at the right and left ends CHARACTERIZED by comprising at least one electric generator set (16) formed by a combustion engine (8) connected to a motor / generator (9) to transfer energy to at least one inverter (5) connected to an electrical connection box (6) which distributes energy to the electric drive units (EDU) composed of reduction gears (4) with neutral position (18), electric motor (17) and an inverter (5), in which the front axle (13) rotated by the cardan shaft (3) is connected to an EDU (4, 17,5) to drive the front wheels (1) and in which each of the rear axle half-shafts (14) is rotated by the energy coming from its respective EDU (4, 17, 5) to propel the rear wheels (2), such that the energy produced by the motor / generator (9) connected to the combustion engine shaft (8) is consumed by the electric motor (17) connected to the front (13) and rear (14) drive axles., 2. Electrical system for a series hybrid agricultural vehicle (20) comprising a front axle (19), steerable and traction, with wheelsets (1) at the right and left ends with distribution of the mechanical power to the wheelsets (1) made individually by an electronic differential with torque vectoring, and rear axle (14) traction with wheelsets (2) at the right and left ends CHARACTERIZED by comprising at least one electric generator set (16) formed by a combustion engine (8) connected to a motor / generator (9) to transfer energy to at least one inverter (5) connected to an electrical connection box (6) that distributes energy to the electric drive units (EDU) composed of reduction gears (4) with neutral position (18), electric motor (17) and an inverter (5), in which each one of the front axle half-shafts (19) is rotated by the energy coming from its respective EDU (4, 17, 5) to drive the front wheels (1) and in which each of the rear axle half-shafts (14) is rotated by the energy coming from its respective EDU (4, 17, 5) to drive the rear wheels (2), such that the energy produced by the motor / generator (9) connected to the combustion engine shaft (8) is consumed by the electric motor (17) connected to the front (19) and rear (14) drive axles.

3. Electrical system according to claim 1 or 2, CHARACTERIZED in that the controllers (5) that form the EDUs (4, 17, 5) are capable of acting electrically in reverse, consuming or producing energy respectively.

4. Electrical system according to any one of the preceding claims, CHARACTERIZED in that the control of the energy production and consumption of the system is carried out in such a way that the excess produced by regenerative braking is dissipated by reacting against the movement of the combustion engine (8).

5. Electrical system according to any one of the preceding claims, CHARACTERIZED in that the control of the rotation and fuel injection of the combustion engine (8) is carried out automatically and without operator interference.

6. Electrical system according to any one of the preceding claims, CHARACTERIZED in that the EDUs (4, 17, 5) of each of the rear axle half-shafts (14) are positioned with an offset in relation to each other.

7. Electrical system according to any one of the preceding claims, CHARACTERIZED in that EDUs (4, 17, 5) are positioned offset in connection with the front axle (19).

8. Electrical system according to any one of the preceding claims, CHARACTERIZED in that only one EDU (4, 17, 5) is positioned to supply power to a mechanical differential, which distributes the torque to the front axle (13) and its wheels (1).

9. Electrical system according to any one of the preceding claims, CHARACTERIZED in that an electronic differential allows independent control of the front wheels (1) of the front axle (19) and independent control of the rear wheels (2) of the rear axle (14).

10. Electrical system according to any one of the preceding claims, CHARACTERIZED in that the EDUs (4, 17, 5) comprise multi-speed reduction gears (4) and neutral position (18), which enables safe towing.

11. Electrical system according to any one of the preceding claims, CHARACTERIZED in that the rear (14) and front (19) half-axles are equipped with an EDU (4, 17, 5), a set of service and stationary brakes actuated / controlled by electro / hydraulic mechanisms (11) and a set of speed reduction gears (10).

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