RU213826U1 - TANGENTIAL ELECTROMECHANICAL DRIVE OF ELECTRIC TRANSPORT - Google Patents

Abstract

The utility model relates to the field of transport technology, in particular to the creation of efficient traction electromechanical drives for electric vehicles. The tangential electromechanical drive of electric transport is an asynchronous AC motor 1 (it can be a DC motor or a motor-wheel), the rotation from which is transmitted through the gears 3 and 7 of the gear train directly to the rim 5 of the drive wheel. The movement of the electric vehicle is carried out by driving wheels, which are located on a fixed axle in free rotation through the bearing assembly. The transfer of torque directly to the rim of the drive wheel, and not through a reduction editor, differential and rotating axle shafts, while maintaining known speed characteristics, reduces the power of electric motors, including by reducing transmission losses. At the same time, the design of the drive is simplified, friction losses in the transmission are removed due to the absence of a gearbox and differential, the battery capacity decreases with an increase in the mileage of an electric vehicle without recharging, and the cost of production of electric vehicles decreases. The utility model is especially relevant for trucks with large diameter wheels, and can also be used in the space industry, when economical and lightweight electric drives are needed for lunar rovers and rovers. 2 ill.

Description

The utility model relates to the field of transport technology, in particular to the creation of efficient traction electromechanical drives for electric vehicles.

Electric transport drives

The variety of known schemes, designs and layout solutions for electric vehicle drives fits into the framework of three main options:

1) central electric motor plus gearbox plus cross-axle mechanical differential;

2) two onboard electric motors, one for each drive wheel;

3) electric motor-wheel.

The first option is the most common and is considered a promising drive for electric vehicles, including those with combined power plants (FR N 2200800 A, B60K 17/00, 1974; US N 3888325 A, B60K 1/00, 1975). Such a traditional drive is installed on electric vehicles of various concerns, such as Tesla, BMW, Mercedes.

The reasons why it is difficult to achieve a technical result is the fact that the design contains an asynchronous motor, in which there is a high consumption of electricity at the start and during acceleration of an electric vehicle, there are also problems with power losses when transmitting high torque through a traditional transmission, where the only difference is the replacement gearboxes of a car with an internal combustion engine to a reduction gear of an electric car.

The second drive option is implemented, in particular, in the Impact electric vehicle developed by General Motors (US Automotive Industry, 1990, No. 5. - p. 7-9). The use of this option is constrained by the high cost of the system and its weight and size.

The third version of the drive is aimed at developing various motor-wheels (patents WO 93/08999 A1, 05/13/93, US 6617746 B1, 09/09/2003; RU 2129965 C1, 05/10/1999; RU 2172261 C1, 08/20/2001; RU 2172261 C1, 20.08.2001).

The difficulties of using this option are associated with unresolved issues of installing high-power electric motors, when the motor-wheel rotation rotor becomes heavy, which leads to problems in their operation due to the prohibitive weighting of the drive wheel itself. When high-power DC electric motors are used in motor-wheels, large starting and transient currents occur at the start of movement and acceleration of electric vehicles, which entails the need to increase the battery capacity.

An analysis of patents shows that all of the above drive options are being improved in the direction of optimizing the design and electrical circuits of the electric motors themselves. At the same time, little attention is paid to improving the mechanical transmission of torque from the drive to the drive wheel, where power transmission in the traditional way is inefficient, and especially when the diameters of the wheels of electric vehicles increase.

An electric vehicle drive is known, containing mainly a three-phase asynchronous motor powered by a frequency converter, connected through a gearbox with wheel axles and a control system. According to the invention, the engine also performs the function of an interwheel differential, which makes it possible to eliminate the mechanical differential. The drive has improved overall dimensions and is cheaper to manufacture (RF Patent No. 2146623, IPC V60K 17/00).

The reasons why the technical result cannot be achieved is that the design contains an asynchronous electric motor, the torque from which is transmitted through a traditional transmission with large losses in the transmitted power. The use of high-power electric motors entails high heat generation, requires a complex control system and high-voltage power supplies.

An electric drive of vehicles is known, the essence of which lies in the fact that an internal magnetic circuit with teeth is additionally installed on the stator housing of the electric drive, if it is executed as an inductor motor. If an inductor consisting of permanent magnets is installed as an external magnetic circuit with teeth, then an internal inductor with permanent magnets is additionally installed. The use of permanent magnets as external and internal stator inductors is necessary if the vehicle requires increased torque. According to the invention, the technical result is to reduce the consumption of electrical energy and increase the torque (RF Patent 2509665, IPC B60L 11/00).

However, the described electric motor does not solve the problem of reducing large starting and transient currents at the beginning of the movement and acceleration of the vehicle, which leads to rapid wear of the batteries and deterioration of the thermal regime.

Known electro-inertial device for an electric vehicle, taken as a prototype, the drive which contains a drive motor, transmission and flywheel, the body of which is made in the form of a pipe with a cutout. The flywheel is placed concentrically inside the body, and its shaft is placed in bearing supports installed at the ends of the pipe, and has two ends protruding from the support. At one end there is a pulley, at the other - a gear wheel of the clutch, made with the possibility of being driven from the starter gear. The drive motor is located at the housing cutout, its shaft axis is parallel to the flywheel shaft axis, and the motor shaft protrudes beyond the housing and is equipped with a pulley. In this case, the pulleys of the flywheel and electric motor shafts are interconnected by a belt drive (RF Patent No. 2230220, IPC: F03G 3/08).

The disadvantages of the known drive device include large starting mechanical loads and high starting currents of the electric motor, which are associated with the need to spin the flywheel weighing about 150 kg. This drive uses a traditional transmission to transmit torque to the axles of the driving wheels, which leads to the need to use an electric motor with increased power due to known frictional losses in power transmission.

As a rule, in electric vehicles, torque is transmitted in the same traditional way as in cars with internal combustion engines. The torque from the electric motor is transmitted to the axle shafts of the driving wheels of the electric vehicle through the drive axle and through the reduction gear assembly with the differential. In the gearbox, the drive gear transmits rotation to the driven gear through a bevel gear at reduced speed. Then, through the satellites of the differential and the axle shaft, rotation is transmitted to the drive wheels.

The rotation of the wheels is prevented by the friction force that appears between the wheels and the road surface. During rotation, the drive wheels create circumferential tangential forces that act on the road, trying to push it back. To obtain the necessary force for the movement of the wheels and, accordingly, the electric vehicle, an appropriate torque is needed.

According to the well-known formula, the torque is equal to the product of the tangential force and the radius of application of this force: M cr.=F⋅R, where M cr. - torque, F - applied force, R - radius of force application.

Then

M cr. - F _axis ⋅ R _axis = F _col ⋅ R _col ,

where M cr. - transmitted torque,

F _axis , F _number - tangential force of rotation transmission on the axle shaft and on the tire of the drive wheel,

R _axis , R _count - the radius of application of force on the axle shaft and on the tire of the drive wheel of the electric vehicle.

Thus, with equal torques, the larger the radius, the smaller the applied force, and vice versa. If we take into account that the radius of the wheel is much larger than the radius of the axle shaft and the driven gear of the gearbox, then the tangential force on the surface of the axle shaft will increase by the same difference. Such power transmission through the axle shafts of the drive wheels is inefficient. This is due both to losses during power transmission through a bulky transmission, and to the need to strengthen all components and parts of the transmission to transmit high torque with high twisting forces of the axle shafts of the wheels themselves. For example, in the rear-wheel drive Tesla Model S, when transmitting torque up to 500 Nm through a traditional transmission, the axle shafts of the drive wheels experience not only a large torque, but also a high tangential torsional force of about 25,000 N. For example, in Tesla electric vehicles with electric motor power 420 HP a huge torque breaks the axle shafts and kills the gearbox (see teslaservice.kiev.ua).

When creating a useful model of a tangential electromechanical drive for electric transport, the problem of creating an efficient drive was solved in a different way compared to the development of new electric motors, namely, reducing the power of the electric motor by transmitting torque directly to the drive wheel rim. At the same time, other tasks were also solved: simplifying the design of an electric vehicle drive, reducing contact forces in torque transmission units and reducing operating costs, incl. and by reducing the capacity of the batteries with a corresponding increase in the range of electric vehicles without recharging.

The problem is solved due to the fact that the transmission of torque is carried out not through the gearbox, differential and rotating semi-axle of the drive wheel, but directly from the electric motor through the gear directly to the rim of the drive wheel, which is located on a fixed axle with the possibility of free rotation. This technical solution allows to reduce the power of the drive motor, its weight, dimensions and cost. This automatically reduces the number and cost of batteries. The cost of producing an electric car is also decreasing, incl. and due to the absence of a gearbox and differential in it.

The utility model is illustrated in the drawings, where in Fig. 1, 2 shows a tangential electromechanical drive of an electric vehicle with torque transmission from the electric motor to the drive wheel according to the option of installing two onboard electric motors, one for each drive wheel. In principle, this scheme is also suitable for other options for transmitting torque, incl. and with the installation of motor-wheels.

The tangential electromechanical drive is an asynchronous three-phase alternating current motor 1, through the axis of which 2 rotation is transmitted to the drive gear 3. The power supply of the engine is transmitted through the frequency converter 4. The drive wheel consists of a wheel rim 5 with a pneumatic tire 6 and a gear wheel 7 fixed on the rim. The wheel rim 5 is mounted on a fixed axle 9 through the bearing assembly 8 with the possibility of free rotation of the drive wheel. The tangential electromechanical drive transmits rotation from the electric motor 1 through the drive gear 3 to the wheel gear 7. The drive is mounted on the suspension of the electric vehicle, which provides a rigid connection of the drive with the fixed axle 9 of the wheel.

Tangential electromechanical drive operates as follows. The power supply of the asynchronous electric motor of three-phase alternating current 1 is carried out from batteries through the inverter and frequency converter 4. When the electric vehicle starts moving, the electric motor 1 of the drive is turned on. The tangential electromechanical drive transmits rotation through a gear train to the drive wheel of the electric vehicle, in particular, the drive gear 3 transmits rotation at a decreasing speed to the gear 7 fixed to the wheel rim 5. The movement of the electric vehicle is carried out by drive wheels, which are located on a fixed axle 9 in free rotation through the bearing assembly 8. All other parts and devices of the drive wheel, incl. the brake and suspension are installed in the traditional version.

The speed of the car is controlled by the speed of the electric motor using a frequency converter. At the same time, it is important that the frequency converter, with an increase or decrease in the speed of the electric motor within +/- 30%, ensures its power and torque are practically unchanged. The engine can act as a generator, for example, when driving downhill.

The utility model presents the basic concept of a tangential electromechanical drive for electric transport. One of the distinguishing features of such a design solution is the fact that the rotation from the electric motor to the drive wheel of the electric vehicle is transmitted directly with virtually no loss. Thus, there is no need to use a traditional transmission with a multi-stage gearbox. He is not here. At the same time, if in existing models of electric vehicles with a gear ratio of 1:10, the speed of rotation of the electric motor decreases by 10 times when transferred to the axle shaft of the drive wheel, respectively, then in the claimed utility model with a tangential electromechanical drive, the gear ratio of the gear train on the wheel is 1:4. This ratio is achieved due to the fact that the rotation from the electric motor is transmitted not to the wheel axle, but to the gear wheel of the wheel rim through the drive gear, the diameter of which is 4 times smaller than the wheel rim gear.

Thus, the utility model makes it possible to significantly reduce the load on the gear teeth and to reduce to zero the torsional forces on the axle of the drive wheels, because the axle does not rotate. At the same time, the drive motor does not need to be forced to achieve high speeds up to 16000 rpm, it is enough to have a simple in design and cheaper electric motor with a speed of about 6000 rpm. This possibility of the utility model is achieved due to the increased speed of the drive pinion in comparison with the speed of rotation of the axle shaft while maintaining the same tangential force for the movement of the electric vehicle. All this leads to a simplification of the drive design, a reduction in loads in transmission mechanisms, a decrease in the power of the electric motor and a reduction in the cost of producing an electric vehicle. At the same time, the capacity of traction batteries, which are the main problem in the development of electric vehicles, also decreases accordingly.

Individual components and mechanisms may have a different design solution while maintaining the transmission of rotation to the drive wheel not through the rotating shaft of the wheel, but through the wheel rim with a fixed shaft. This applies, for example, to gearing. Another may be the motor itself, such as a DC motor, which eliminates the need for an inverter and a frequency converter. The utility model, by its design solution, actually solves the problem of motor-wheels, which is associated with an increase in the critical weight of the driving wheels with an increase in the power of the drive motors of the motor-wheels.

The utility model may have more than one electric motor per drive wheel with motor-generator functions. In this case, for example, about two electric motors, when accelerating or driving up an inclined road, both motors are turned on. This allows you to quickly develop the desired speed and overcome a difficult section of movement. On a flat road, one electric motor drives the drive wheel, and the second as a generator to recharge the batteries. When driving down an incline, both electric motors work as generators. Controlling the operation of electric motors, for example, through the sensor of the Torque Sensor device, will allow you to synchronize the engine speed with the optimal torque. This arrangement will allow for efficient recharging of batteries while driving, providing an increase in the mileage of an electric vehicle before stationary recharging.

The utility model can also be applied to vehicles with internal combustion engines. It is also relevant for hybrid vehicles.

The use of the utility model is most effective on vehicles with large wheels, such as trucks or mining dump trucks for hauling ore. In this case, in the traditional version, the engine must have a huge power with the same high torque to transmit rotation through half shafts with a much larger diameter. The proposed tangential electromechanical drive radically solves the problem of twisting of the axle shafts of the driving wheels and the failure of gearboxes due to high voltages in the drive mechanisms of trucks. The larger the wheel in its diameter, the farther from the wheel axis is the tangential electromechanical drive itself and the less energy is needed to transmit torque from the electric motor to the drive wheels. This approach could accelerate the transition from gasoline-diesel to electric propulsion in trucks and hybrid vehicles.

The utility model can also be used in the space industry, when lunar rovers and rovers need economical and lightweight electric drives. This will reduce the weight of these vehicles and reduce the capacity of the power plant from solar panels.

Claims (3)

1. A tangential electromechanical drive for electric transport, containing an electric motor and a drive for transmitting torque from the electric motor to the rim of the drive wheel, characterized in that the torque is transmitted from a DC electric motor. 2. Tangential electromechanical drive according to claim 1, characterized in that the DC motor is made in the form of a wheel motor. 3. Tangential electromechanical drive according to paragraphs. 1, 2, characterized in that the transmission of torque can be carried out from one or more electric motors, which can also operate in generator mode.

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