SK289114B6 - Propulsion with three electric motors, two planetary gears and a differential - Google Patents

Abstract

A propulsion with three electric motors, two planetary gears and a differential comprises a first electric motor with stator (1) and rotor (2), a second electric motor with stator (4) and rotor (5) and a third electric motor with stator (4a) and rotor (5a). The stator (1) of the first electric motor is firmly connected to the stator (4) of the second electric motor and to the stator (4a) of the third electric motor. The shaft (3) of the rotor (2) of the first electric motor is connected to the central wheel (9) of the first planet transmission and with the central wheel (9a) of the second planetary transmission. The rotor (5) of the second electric motor is connected to a crown wheel (6) which is provided with a brake disc (10) of the brake (11) anchored as well as the stator (1) of the first electric motor. The ring gear (6) and the central wheel (9) engage with satellites (7) connected by a carrier (8) which is connected to the output shaft (12). The rotor (5a) of the third electric motor is connected to the ring gear (6a) which is equipped with a brake disc (10a) a brake (11a) anchored in the same way as the stator (1) of the first electric motor. The crown wheel (6a) and the central wheel (9a) engage with satellites (7a) connected by a carrier (8a) which is connected to the output shaft (12a). The ring gear (6) is provided with a differential carrier (14), the ring gear (6a) is provided with a differential carrier (14a) and the carriers (14) and (14a) are in contact with the differential satellite (15).

Description

The field of technology

The invention relates to a drive with three electric motors, two planetary gearboxes and a differential for use mainly in electric cars.

Current state of the art

Nowadays, high torque is required in every vehicle at start-up. In a classic car, first gear has a high gear ratio. Only a small speed is achieved in the first gear, and therefore other gears are arranged, which reduce the gear ratio and higher speeds are achieved.

Most current electric cars use a constant gear ratio from 3:1 to 12:1, depending on the purpose of the vehicle and the characteristics of the engine, because the electric motor can develop a high torque even at low revolutions and also reaches high revolutions to achieve high vehicle speeds. The disadvantage of permanent transmission is the low efficiency of the electric motor at low speeds, which in city traffic can reduce its range by up to 50% without recuperation. At high speeds, the electric motor loses torque, which results in low dynamics.

The essence of the invention

The mentioned shortcomings are eliminated in the present invention, the essence of which is formed by a drive with three electric motors, two planetary gearboxes and a differential, which contains a first electric motor with a stator and a rotor, a second electric motor with a stator and a rotor, and a third electric motor with a stator and a rotor, where the stator of the first electric motor is connected to the stator of the second electric motor and to the stator of the third electric motor, which are connected to the frame or body of the vehicle, while the rotor shaft of the first electric motor is connected to the central wheel of the first planetary gear and also to the central wheel of the second planetary gear, where the rotor of the second electric motor is connected to by the crown wheel, which is equipped with a brake disk of the brake anchored in the same way as the stator of the first electric motor, which is connected to the frame or body of the vehicle, then the crown wheel and the central wheel engage with the satellites connected by the follower, which is connected to the output shaft, then the rotor of the third electric motor is connected with the crown wheel of the second gear, which is equipped with a brake disk of the brake anchored in the same way as the stator of the first electric motor, then the crown wheel and the central gear engage with the satellites connected by the carrier, which is connected to the output shaft, while the crown wheel of the first planetary gear is equipped with the carrier of the differential and the crown the wheel of the second planetary gear is equipped with a differential carrier, and the carriers are in contact with the differential satellite.

Overview of images on drawings

The picture shows a schematic representation of the drive consisting of three electric motors, two planetary gearboxes and a differential.

Examples of implementation of the invention

The drive with three electric motors, two planetary gearboxes and a differential includes the first electric motor with stator 1 and rotor 2, the second electric motor with stator 4 and rotor 5 and the third electric motor with stator 4a and rotor 5a, where the stator 1 of the first electric motor is firmly anchored and connected to by the stator 4 of the second electric motor and with the stator 4a of the third electric motor, which is connected to the frame or body 13 of the vehicle, while the shaft 3 of the rotor 2 of the first electric motor is connected to the central wheel 9 of the first planetary gear and also to the central wheel 9a of the second planetary gear, where the rotor 5 of the second electric motor is connected to the crown wheel 6, which is equipped with the brake disk 10 of the brake 11 anchored in the same way as the stator 1 of the first electric motor, which is connected to the frame or body 13 of the vehicle, then the crown wheel 6 and the central wheel 9 engage with the satellites 7 connected by the carrier 8 , which is connected to the output shaft 12, then the rotor 5a of the third electric motor is connected to the crown wheel 6a, which is equipped with a brake disc 10a of the brake 11a anchored in the same way as the stator 1 of the first electric motor, then the crown wheel 6a and the central wheel 9a engage with satellites 7a connected carrier 8a, which is connected to the output shaft 12a, wherein the ring gear 6 is equipped with a carrier 14 of the differential and the ring gear 6a is equipped with a carrier 14a of the differential, and the carriers 14 and 14a are in contact with the satellite 15 of the differential. The drive can be structurally solved on one axis, which makes it a compact unit of small dimensions easily placed on the vehicle axle, with driven shafts on both sides, with the option where each side can work in a different mode, torquevectoring.

The three-motor electric drive consists of three electric motors, two planetary gearboxes, two brakes and a differential.

For start-up, the satellite 15 of the differential is activated to the position when it connects the carriers 14, 14a of the differential. Thus, the rotor 5 of the second electric motor connected to the crown wheel 6, the rotor 5a of the third electric motor connected to the crown wheel 6a and the satellite 15 work together as a drive differential. Then the crown wheels 6 and 6a cannot rotate in parallel, but each in the opposite direction. By activating the first electric motor, which connects the central wheels 9 and 9a through the shaft 3, it rotates them in one direction, and through the satellites 7 and 7a, they rest on the crown wheels 6 and 6a, which can only rotate in the opposite direction, and therefore they are fixed and the satellites 8 and 8a are driven rotate in parallel and transmit revolutions to the output shafts 12 and 12a. In this mode, the drive works on both sides as a motor with planetary gearboxes with fixed crown wheel 6 and 6a. The gearboxes have a higher gear ratio, for example 10:1, which is a good setting for starting and driving at low speeds up to 60 km/h. In this way, the drive easily overcomes the starting torque of the vehicle, and the first electric motor operates in a small range of drive output speeds, which increases its efficiency. With such a high gear ratio, the vehicle has high dynamics at start-up, even with a lower power electric motor, which will reduce energy consumption.

In the start-up mode, the satellites 7 and 7a are supported by the fixed crown wheel 6 and 6a by the force transmitted from the central wheel 9 and 9a. After overcoming the starting torque of the vehicle, the force transmitted to the crown wheel 6 and 6a is lower, and the satellites 7 and 7a rotating on the carrier 8 and 8a drag the crown wheel 6 and 6a in the direction of rotation of the satellite carrier 8 and 8a, thereby further reducing the force acting on the crown wheel 6 and 6a.

To achieve a higher speed, the drive mode is changed so that the first electric motor is active, has reached its maximum effective speed and started the vehicle. The differential satellite 15 is activated to the position in which it releases the differential carriers 14 and 14a. The second electric motor in the direction of rotation of the output shaft 12 of the drive and the third electric motor in the direction of rotation of the output shaft 12a of the drive are activated. By increasing the speed of the rotor 5 of the second electric motor and the connected crown wheel 6 of the first gearbox and the rotor 5a of the third electric motor and the connected crown wheel 6a of the second gearbox, the gear ratio of the planetary gearboxes will decrease, and thus the revolutions of the output shafts 12 and 12a will increase. This change in the transmission and the revolutions of the output shaft 12 and 12a is smooth. In this way, the electric motors of the drive operate in a more optimal range of their efficiency at both low and high output speeds of the drive.

When driving through a corner and simultaneously accelerating, the outer wheel of the vehicle is loaded more and therefore can transmit a greater torque to the road than the inner wheel. In this mode, the load of the second electric motor can be different than the load of the third electric motor, and this means a different torque on the output shafts 12 and 12a, torquevectoring. If the crown wheels 6 and 6a of the planetary gearboxes are fixed, the transmission ratio of the gearboxes is 10 : 1. If the crown wheels 6 and 6a have the same revolutions as the output shafts 12 and 12a, the gear ratio is 1 : 1. If the crown wheels 6 and 6a have half revolutions as the output shafts 12 and 12a, the gear ratio is 5:1. The gear ratio 10:1 is not fixed and is used as an example for better explanation.

To transition from the high-speed mode to the run-up mode, the brakes 11 and 11a are activated to stop the carriers 14 and 14a. Then the satellite 15 is activated to the position when it connects the carriers 14 and 14a, then the brakes are deactivated.

If one of the vehicle's wheels slips, the slipping wheel can be braked electronically by the second electric motor or the third electric motor, or by both electric motors at the same time, since they are interconnected by the satellite 15, or by braking the discs 10 and 10a of the brake 11 and 11a. In this way, it is possible to actively control the slipping wheel of the vehicle. Full activation of one or both brakes 11 and 11a closes the differential.

Recuperation: When recuperating at higher speeds, all three drive electric motors recuperate electrical energy and the level of recuperation, and therefore the braking force can be different for output shafts 12 and 12a because electric motor 2 and electric motor 3 are independent in this mode, for example when driving around a corner.

In city traffic, it is necessary to recover electrical energy while reaching the lowest possible vehicle speeds. The drive in start-up mode has a higher gear ratio than conventional electric drives, so it can recover electrical energy at lower vehicle speeds, which brings more electrical energy back to the battery.

The start-up and reaching the maximum speed is in table 1.

Values for the given example:

gear ratio of the input and output shaft of the planetary gearbox 10:1, gear ratio of the crown wheel and output shaft of the planetary gearbox 1.1:1, the torque of the first electric motor is 20 Nm, the torque of the second electric motor is 20 Nm, the torque of the second electric motor is 20 Nm , vehicle wheel diameter 2 m.

Electric motor 1 Electric motor 2 Electric motor 3 Differential Planetary gearboxes Drive output shafts Vehicle speed Engine torque 1 Engine torque 2 Engine torque 3 Speed 1/min. Speed 1/min. active Yes/No Gear ratio Speed 1/min. km/h At the output Nm At the output Nm At the output Nm 500 0 Yes 10 : 1 50 6 200 0 0 1000 0 Yes 10 : 1 100 12 200 0 0 1,500 0 Yes 10 : 1 150 18 200 0 0 2000 0 Yes 10 : 1 200 24 200 0 0 2,500 0 Yes 10 : 1 250 30 200 0 0 3000 0 Yes 10 : 1 300 36 200 0 0 4000 0 Yes 10 : 1 400 48 200 0 0 5,000 0 Yes 10 : 1 500 60 200 0 0 6,000 0 Yes 10 : 1 600 72 180 0 0 7,000 0 Yes 10 : 1 700 84 150 0 0 8,000 0 Yes 10 : 1 800 96 120 0 0 9,000 0 Yes 10 : 1 900 108 90 0 0 10,000 0 Yes 10 : 1 1000 120 60 0 0 5,000 100 Not 8.5:1 591 71 169 22 22 5,000 200 Not 7.3 : 1 682 82 147 22 22 5,000 300 Not 6.5:1 773 93 129 22 22 5,000 400 Not 5.8:1 864 104 116 22 22 5,000 500 Not 5.2 : 1 955 115 105 22 22 5,000 600 Not 4.8 : 1 1045 125 96 22 22 5,000 700 Not 4.4:1 1 136 136 88 22 22 5,000 800 Not 4.1:1 1 227 147 81 22 22 5,000 900 Not 3.8 : 1 1 318 158 76 22 22 5,000 1000 Not 3.5:1 1 409 169 71 22 22

Tab. 1

By changing the speed ratio of the first and second electric motor or the first and third electric motor, it is possible to change the gear ratio of the planetary gearbox at the same vehicle speed, see tab. 2, thereby changing the torque on the output shaft 12 and 12a of the drive. In this way, it is possible to set the electric motors so that they work at the optimal speed of their efficiency for a given vehicle speed, both for driving at a constant speed, 15 and for maximum dynamics at low and higher speeds.

Electric motor 1 Electric motor 2 Electric motor 3 Differential Planetary gearboxes Drive output shafts Vehicle speed Engine torque 1 Engine torque 2 Engine torque 3 Speed 1/min. Speed 1/min. Active Yes/No Gear ratio Speed 1/min. km/h At the output Nm At the output Nm At the output Nm 5,000 0 Yes 10 : 1 500 60 200 0 0 4000 110 Not 8 : 1 500 60 160 22 22 3000 220 Not 6 : 1 500 60 120 22 22

Electric motor 1 Electric motor 2 Electric motor 3 Differential Planetary gearboxes Drive output shafts Vehicle speed Engine torque 1 Engine torque 2 Engine torque 3 2000 330 Not 4 : 1 500 60 80 22 22 1000 440 Not 2 : 1 500 60 40 22 22 500 495 Not 1 : 1 500 60 20 22 22 5,000 550 Not 5:1 1000 120 100 22 22 4000 660 Not 4 : 1 1000 120 80 22 22 3000 770 Not 3 : 1 1000 120 60 22 22 2000 880 Not 2 : 1 1000 120 40 22 22 1000 990 Not 1 : 1 1000 120 20 22 22

Tab. 2

Claims (1)

PATENT CLAIMS A drive with three electric motors, two planetary gearboxes and a differential, characterized in that it contains a first electric motor with a stator (1) and a rotor (2), a second electric motor with a stator 5 (4) and a rotor (5) and a third electric motor with a stator (4a ) and rotor (5a), where the stator (1) of the first electric motor is firmly anchored and is connected to the stator (4) of the second electric motor and to the stator (4a) of the third electric motor, while the shaft (3) of the rotor (2) of the first electric motor is connected to with the central wheel (9) of the first planetary gearbox and also with the central wheel (9a) of the second planetary gearbox, where the rotor (5) of the second electric motor is connected to the crown wheel (6), which is equipped with the brake disc (10) of the brake (11) 10 anchored the same as the stator (1) of the first electric motor, then the crown wheel (6) and the central wheel (9) engage with the satellites (7) connected by the follower (8) which is connected to the output shaft (12), then the rotor (5a) of the third electric motor is connected to the crown wheel (6a), which is equipped with the brake disk (10a) of the brake (11a) anchored in the same way as the stator (1) of the first electric motor, then the crown wheel (6a) and the central wheel (9a) engage with the satellites (7a) connected carrier (8a), which is connected to the output shaft (12a), 15 while the crown wheel (6) is equipped with a carrier (14) of the differential and the crown wheel (6a) is equipped with a carrier (14a) of the differential, and the carriers (14) and ( 14a) are in contact with the satellite (15) of the differential.