DE102022002616A1 - Torque distribution using a continuously variable transmission - Google Patents

Abstract

An electric drive unit 100 for driving left and right wheels 108 of an electric vehicle is disclosed, comprising: an electric motor 102 to provide tractive power to the wheels 108; and a pair of continuously variable transmissions/CVT 104 coupled to an output shaft 120 of engine 102 . Each CVT 104 is configured to transmit tractive power from the electric motor 102 to a corresponding wheel 108 . The CVT 104 are configured to provide a speed ratio that allows the CVT 104 to provide a low gear ratio between the electric motor 102 and the wheels 108 in addition to torque split between the vehicle's left and right wheels 108 .

Description

The present disclosure relates generally to the technical field of automotive power transmission systems. In particular, it relates to a continuous torque distribution between two wheels of an axle of a vehicle.

Conventionally powered vehicle axles include a differential designed to provide traction drive for the appropriate pair of wheels while allowing them to rotate at different speeds as the vehicle rotates. The differential allows the outside drive wheel to spin faster than the inside drive wheel, causing the wheel going around the outside of the turning curve to roll farther and faster than the other. In conventional axles with the differential, the average speed of the two drive wheels equals the input speed to the differential, with an increase in outer wheel speed being offset by a decrease in inner wheel speed, thereby keeping the torque at both wheels equal.

Therefore, the conventional differentials are not able to control torque that is transferred to different wheels, i. H. Torque distribution between wheels. For reasons of driving dynamics, it is appropriate that the input torque is divided between wheels in different ways depending on the driving condition. Known torque-on-demand systems enable variable torque distribution of the torque via a multi-plate clutch, but do not provide any active and controlled redistribution of the torque to the wheels. While torque distribution with clutches meets the requirement to some extent, slippage in the clutch during torque transfer makes it inefficient to manage. It would therefore be beneficial to provide an efficient torque split between wheels to meet the demand depending on the driving condition.

The advent of electric vehicles, with increasingly demanding improvements in the performance of electric drive units, provides an opportunity to improve the efficiency and stability of vehicle propulsion systems.

DE102016217626 discloses a drive axle for a motor vehicle comprising at least a left wheel and a right wheel, and a single electric machine having a first output shaft for driving the left wheel and a second output shaft for driving the right wheel. A first toroidal continuously variable transmission (CVT) is connected between the first output shaft and the left wheel and a second toroidal CVT is connected between the second output shaft and the right wheel, in line with the corresponding output shafts, resulting in power transmission only leads in a coaxial direction.

WO2018045121A1 discloses an electric axle drive including a continuously variable electric drive train having a motor/generator and a continuously variable transmission. A drive wheel axle is operably coupled to the continuously variable electric drive train, and a first wheel and a second wheel are coupled to the drive wheel axle. A differential is coupled to the continuously variable electric drive train and the drive wheel axle. A planetary gear is coupled to the drive wheel axle and the continuously variable electric drive train.

WO2020212054A1 discloses a drive arrangement for a motor vehicle for driving motor vehicle wheels, with a two-shaft drive with two electric motors. The axle drive structure has a first drive shaft and a second drive shaft, a first prime mover driving the first drive shaft and a second prime mover driving the second drive shaft.

As can be seen, the references cited disclose different types of electric drive units for different distribution of the drive torque provided by the electric machine to the two wheels. However, it is possible to provide an improved electric drive unit that is more efficient in distributing drive torque from the electric machine to the two wheels.

There is therefore a need to provide a powertrain system for front/rear/four-wheel drive vehicles that allows torque distribution between both wheels of any axle.

A general object of the present disclosure is to provide an improved power transmission system that allows the distribution of torque for the two side wheels as required depending on the prevailing driving condition.

An object of the present disclosure is to overcome disadvantages of conventional system methods used for torque distribution between wheels.

Another object of the present disclosure is to reduce any power loss during torque distribution.

Another object of the present disclosure is to eliminate the requirement for a differential.

Another object of the present disclosure is to provide an electric drive unit that does not require a separate electric motor for torque distribution.

Aspects of the present disclosure relate to traction power transmission systems in electric vehicles, such as. B. a system for transmitting traction power from an electric motor to a set of left wheels and right wheels, and an electric drive unit of the traction power transmission system. In one aspect, the present disclosure provides an electric drive unit (EDU) that provides torque distribution based on a pair of continuously variable drives, wherein the continuously variable drives are configured to provide a speed ratio that allows the EDU, in addition to torque distribution between the left wheels and right wheels of the vehicle, provides any required gear ratio between the electric motor and the wheels.

In one aspect, the disclosed electric drive unit includes an electric motor configured to provide tractive power to left wheels and right wheels of the vehicle; and a pair of continuously variable drives coupled to an output shaft of the electric motor. Each of the continuously variable drives is configured to transmit tractive power from the electric motor to a corresponding wheel of the vehicle. The pair of continuously variable drives is configured to provide a speed ratio that allows the continuously variable drives to provide any required gear ratio between the electric motor and the wheels, in addition to torque distribution between the left wheels and right wheels of the vehicle.

In one embodiment, the electric drive unit includes a pair of planetary gears, each planetary gear being configured between the continuously variable drives and the corresponding one of the left wheels and right wheels of the vehicle.

In one embodiment, the pair of continuously variable drives can be configured to provide any speed ratio for a single-speed reduction gear based configured CVT design.

In one embodiment, the pair of continuously variable drives can provide any speed ratio and reduction ratio for a multi-speed transmission based on configured CVT design.

In one embodiment, the pair of continuously variable drives can provide any required gear ratio between the electric motor and the wheels when one of the two continuously variable drives is actuated to provide any required ratio and the other of the two continuously variable drives is actuated to provide an opposite of the other ratio to provide.

In one embodiment, the pair of continuously variable drives are operable to apply different torques to the left and right wheels of the vehicle to assist in dynamic cornering.

In one embodiment, the pair of continuously variable drives may be a variable diameter pulley based transmission.

One aspect of the present disclosure relates to a system for transferring tractive effort from an electric motor to a set of left wheels and right wheels of an electric vehicle. The proposed system includes an electric drive unit for driving a set of left wheels and right wheels of an electric vehicle, the electric drive unit having an electric motor configured to provide traction for the left wheels and right wheels of the vehicle; and a pair of continuously variable drives coupled to an output shaft of the electric motor. Each of the continuously variable drives is configured to transmit tractive force from the electric motor to a corresponding one of the vehicle's left wheels and right wheels. The system further includes any type of actuation system (a hydraulic system) to actuate the pair of continuously variable drives; a controller operatively coupled to the hydraulic system to actuate the pair of continuously variable drives; and a steering angle sensor coupled to the controller to provide inputs to the controller regarding the steering angle of the vehicle. The pair of continuously variable drives is configured to provide a speed ratio that allows the continuously variable drives to provide any required gear ratio between the electric motor and the wheels, in addition to torque distribution between the left wheels and right wheels of the vehicle during steering of the vehicle.

In one embodiment, the pair of continuously variable drives may be a variable diameter pulley based transmission and includes pairs of tapered pulleys. The actuation system (such as a hydraulic system) is configured to change the spacing between the pairs of tapered pulleys to change the diameter of the variable diameter pulleys.

In one embodiment, the pair of continuously variable drives can be configured to provide any speed ratio, and the pair of continuously variable drives can provide any gear ratio between the electric motor and the wheels when both continuously variable drives are actuated to provide an equal ratio.

In one embodiment, the pair of continuously variable drives can be configured to provide any speed ratio for a single-speed reduction gear or can be configured to provide any speed ratio as well as reduction ratio for multi-speed transmissions based on configured CVT construction between the electric motor and the wheels.

Various objects, features, aspects and advantages of the subject invention will become apparent from the following detailed description of preferred embodiments, taken in conjunction with the accompanying drawings in which like numerals represent like components.

• 1 ist eine schematische Darstellung der offenbarten elektrischen Antriebseinheit für Drehmomentverteilung zwischen Rädern eines Fahrzeugs gemäß Ausführungsformen der vorliegenden Offenbarung.
• 2A bis 2E veranschaulichen die Funktion der offenbarten elektrischen Antriebseinheit von 1 unter unterschiedlichen Fahrbedingungen des Fahrzeugs gemäß Ausführungsformen der vorliegenden Offenbarung.
• 3 veranschaulicht ein System zur Übertragung von Traktionskraft von einem Elektromotor zu einem Satz linker Räder und rechter Räder eines Elektrofahrzeugs gemäß Ausführungsformen der vorliegenden Offenbarung.

The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate example embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

• 1 1 is a schematic representation of the disclosed electric drive unit for torque distribution between wheels of a vehicle according to embodiments of the present disclosure.
• 2A until 2E illustrate the function of the disclosed electric drive unit of FIG 1 under different driving conditions of the vehicle according to embodiments of the present disclosure.
• 3 11 illustrates a system for transferring tractive force from an electric motor to a set of left wheels and right wheels of an electric vehicle, in accordance with embodiments of the present disclosure.

The following is a detailed description of embodiments of the disclosure, which are illustrated in the accompanying drawings. The embodiments are detailed in order to clearly communicate the disclosure. However, the amount of detail provided is intended to limit the anticipated variations of embodiments; on the contrary, it is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.

Embodiments explained herein relate to traction power transmission systems in electric vehicles, such as e.g. B. a system for transmitting traction power from an electric motor to a set of left wheels and right wheels, and an electric drive unit of the traction power transmission system. In one aspect, the present disclosure provides an electric drive unit (EDU) that provides torque distribution based on a pair of continuously variable drives, wherein the continuously variable drives are configured to provide a speed ratio that allows the EDU, in addition to torque distribution between the left wheels and right wheels of the vehicle, provides any required gear ratio between the electric motor and the wheels.

With reference to 1 The disclosed electric drive unit (EDU) 100 for an electric vehicle includes an electric motor 102 with an output shaft 120. The output shaft 120 of the electric motor 102 can extend on either side of the electric motor 102 and can have a pair of continuously variable drives, from a continuously variable transmission (continuously variable transmission, CVT), such as B. CVT 104-1 and 104-2 (collectively referred to as CVT 104), may be coupled to the output shaft 120 of the electric motor 102 on two sides of the electric motor 102, as in FIG 1 shown. The two CVT 104 may be configured to transfer tractive power from the electric motor 102 to the corresponding side wheel, such as. B. left wheel 108-1 and right wheel 108-2 (collectively referred to as wheel 108). The two CVTs 104 can independently control the torque and speed required by each wheel 108 .

As in 1 As shown, the output of the CVT 104 may be coupled to a corresponding side shaft, such as. B. a left sideshaft 110-1 and right sideshaft 110-2 (collectively referred to as sideshafts 110) to transfer power from the corresponding CVT 104 to the corresponding wheels 108.

In one embodiment, the EDU 100 may also include a pair of wheel planetary gears, such as. B. left planetary gear set (PGS) 106-1 and right planetary gear set (PGS) 106-2 (together PGS 106), between the output of the CVT 104 and the corresponding wheels 108. The PGS 106 can be configured to a fixed Provide gear ratio as reduction. In implementation, the PGS 106 may reside in hubs of the respective wheels 108 .

In one embodiment, each of the two CVTs 104 may be a variable diameter pulley based transmission and configured to provide any speed ratio based on the CVT design.

In one embodiment, the pair of CVTs 104 can provide any required gear ratio between the electric motor 102 and the wheels 108 when both CVTs 104 are actuated to provide the same ratio.

In one embodiment, the pair of continuously variable drives can provide any required gear ratio between the electric motor and the wheels when one of the two continuously variable drives is actuated to provide a ratio between any required ratio and the other of the two continuously variable drives is actuated to provide an opposite one to provide the other relationship.

In one embodiment, the CVTs 104 are operable to apply different torques to the vehicle's left wheel 108-1 and right wheel 108-2 to assist in dynamic cornering.

2A until 2E illustrate the function of the disclosed electric drive unit of FIG 1 under different driving conditions of the vehicle, wherein 2A a scenario shows when the vehicle is traveling on a straight road as indicated by the arrow on the left side of 2A indicated, with equal traction on both wheels 108 and both wheels 108 must be rotating at the same speed so both CVTs 104 would be operated in the same gear ratio. Because traction is equal at both wheels 108 , equal torque and thus equal power can be delivered to both wheels 108 .

2 B 12 shows a scenario when the vehicle is making a left turn, as indicated by arrow 202 on the left side of FIG 2 B is displayed, during which time the inside wheel, ie left wheel 108-1, must rotate at less speed, thus the left CVT 104-1 would be operated at a gear ratio to reduce speed. This change in speed can also be applied to the right CVT 104-2 in the opposite direction, increasing the speed of the right wheel 108-2.

2C FIG. 12 shows a scenario when the vehicle is making a right turn, as indicated by arrow 204 on the left side of FIG 2C is displayed, during which time the inner wheel, ie the right wheel 108-2, must rotate at a lower speed. Accordingly, the right CVT 104-2 would be operated in a gear ratio to reduce speed. This change in speed can also be applied to the left CVT 104-1 in the opposite direction, increasing the speed of the left wheel 108-1.

2D 12 shows a scenario when the vehicle is traveling on a straight road with different traction on both wheels 108. While traveling on a straight road, as indicated by arrow 206 on the left side of FIG 2D indicated, due to road conditions, the left wheel 108-1 may have good traction and the right wheel 108-2 may have poor traction. The speed of both wheels must be the same so that both CVT 104 are operated in the same proportions. Because the right wheel 108 - 2 has poor traction, it will require less torque and in turn will draw less energy from the electric motor 102 . At the same time, the left wheel 108-1 can draw the energy needed for traction. As a result, unequal torques are supplied to the two wheels 108 .

2E FIG. 12 shows a scenario when the vehicle is required to take a dynamic turn due to unequal torque for the left and right wheels 108. FIG. While turning right on a road as indicated by arrow 208 on the left side of FIG 2E specified, the inner wheel, ie the right wheel 108-2, must rotate at a lower speed, and if the left wheel 108-2 has good traction and the right wheel 108-2 has poor traction, the right CVT 104-2 should be in be operated in a gear ratio to reduce speed also for torque, ie it will be operated to provide the required torque rather than equal torque. Whereas the wheel 108 with good traction can receive the required torque.

One aspect of the present disclosure relates to a system for transferring tractive effort from an electric motor to a set of left wheels and right wheels of an electric vehicle. The proposed System 300, as in 3 shown includes an electric drive unit 100 for driving a set of left wheels 108-1 and right wheels 108-2 of an electric vehicle. The EDU 100 includes an electric motor 102 to provide tractive power to the left wheels 108-1 and right wheels 108-2 of the vehicle; and a pair of continuously variable transmissions/CVT 104 coupled to an output shaft of electric motor 102 . Each of the CVTs 104 may be configured to transmit tractive power from the electric motor 102 to a corresponding wheel 108 of the vehicle.

The system 300 may also include any actuation system (such as a hydraulic system) 302 to actuate the CVT 104; a control unit 306 operatively coupled to the hydraulic system 302 to actuate the CVT 104; and a steering angle sensor 304 coupled to the controller 306 to provide inputs to the controller 306 regarding the steering angle of the vehicle. The CVT 104 may be configured to provide a speed ratio that allows the CVT, in addition to splitting torque between the vehicle's left wheel 108-1 and right wheel 108-2 during vehicle steering, to provide any required gear ratio between the electric motor 102 and the wheels 108 provide.

In one embodiment, the CVT 104 may be a variable diameter pulley based transmission and includes pairs of tapered pulleys. The hydraulic system 302 can be configured to change the spacing between the pairs of tapered pulleys to change the diameter of the variable diameter pulleys.

In one embodiment, the CVTs 104 may be configured to provide a speed ratio and the CVT pair may provide any ratio between the electric motor 102 and the wheels 108 when both CVTs/CVTs 104 are actuated to provide an equal ratio .

Therefore, the present disclosure provides an improved EDU 100 that allows active and controlled reallocation of torque between the left and right side wheels 108 to meet the demand of the prevailing driving conditions. In addition to torque splitting, the CVT 104 of the EDU 100 are configured to provide any speed ratio for a single-speed reduction gear, or may be configured to provide any speed ratio as well as reduction ratio for multi-speed transmissions based on configured CVT construction between the electric motor and the wheels.

While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the following claims. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person skilled in the art to make and use the invention when combined with information and knowledge available to the person skilled in the art.

The present disclosure provides an improved power transmission system that allows the distribution of torque for the two side wheels as required depending on the prevailing driving condition.

The present disclosure overcomes disadvantages of conventional system methods used for torque distribution between wheels.

The present disclosure reduces any power loss during torque split.

The present disclosure eliminates the requirement for a differential.

The present disclosure provides an electric drive unit that does not require a separate electric motor for torque distribution.

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102016217626 [0005]
• WO 2018045121 A1 [0006]
• WO 2020212054 A1 [0007]

Claims (10)

An electric drive unit (100) for driving a set of left wheels and right wheels (108) of an electric vehicle, the electric drive unit (100) comprising: an electric motor (102) configured to provide tractive power to the left wheels and right wheels (108) of the vehicle; and a pair of continuously variable drives (104) coupled to an output shaft (120) of the electric motor (102), each of the continuously variable drives (104) being configured to provide tractive power from the electric motor (102) to a corresponding wheel (108). to transmit to the left wheels and right wheels of the vehicle; wherein the pair of continuously variable drives (104) is configured to provide a speed ratio that allows the continuously variable drives (104), in addition to torque distribution between the left wheels and right wheels (108) of the vehicle, a low gear ratio between the electric motor (102 ) and the wheels (108). Electric drive unit (100) after claim 1 wherein the electric drive unit (100) comprises a pair of planetary gears (106), each planetary gear (106) being configured between the continuously variable drives (104) and the corresponding wheel (108) of the left wheels and right wheels (108) of the vehicle . Electric drive unit (100) after claim 2 wherein the pair of continuously variable drives (104) is configured to provide any speed ratio. Electric drive unit (100) after claim 3 wherein the pair of continuously variable drives (104) provides any required gear ratio between the electric motor (102) and the wheels (108) when both continuously variable drives (104) are actuated to provide an equal ratio. Electric drive unit (100) after claim 3 wherein the pair of continuously variable drives (104) provides any required gear ratio between the electric motor (102) and the wheels (108) when one of the two continuously variable drives (104) is actuated to provide a ratio between any required ratio and the other of the two continuously variable drives is actuated to provide an opposite of the other ratio. Electric drive unit (100) after claim 3 wherein the pair of continuously variable drives (104) are operable to apply different torques to the left and right wheels (108) of the vehicle to assist in dynamic cornering. Electric drive unit (100) after claim 1 wherein the pair of continuously variable drives (104) is a variable diameter pulley based transmission. A system (300) for transferring tractive effort from an electric motor (102) to a set of left wheels and right wheels (108) of an electric vehicle, the system (300) comprising: an electric drive unit (100) for driving a set of left wheels and right wheels (108) of an electric vehicle, the electric drive unit (100) comprising: an electric motor (102) configured to provide tractive power to the left wheels and right wheels (108) of the vehicle; and a pair of continuously variable drives (104) coupled to an output shaft (120) of the electric motor (102), each of the continuously variable drives (104) being configured to provide tractive power from the electric motor (102) to a corresponding wheel (108). to transmit to the left wheels and right wheels of the vehicle; a hydraulic system (302) to actuate the pair of continuously variable drives (104); a control unit (306) operatively coupled to the hydraulic system (302), to actuate the pair of continuously variable drives (104); a steering angle sensor (304) coupled to the controller (306) to provide inputs to the controller (306) regarding the steering angle of the vehicle; wherein the pair of continuously variable drives (104) is configured to provide a speed ratio that allows the continuously variable drives (104), besides torque distribution between the left wheels and right wheels (108) of the vehicle during steering of the vehicle, any required gear ratio provide between the electric motor (102) and the wheels (108). system (300) after claim 8 wherein the pair of continuously variable drives (104) is a variable diameter pulley based transmission, each of the variable diameter pulleys comprising pairs of tapered pulleys, and the hydraulic system (302) is configured to taper the distance between the pairs Changing pulleys to change the diameter of variable diameter pulleys. system (300) after claim 8 wherein the pair of continuously variable drives (104) is configured to provide any required gear ratio between the electric motor (102) and the wheels (108) when both continuously variable drives (104) are actuated to provide an equal ratio.

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