DESC:CONTINUOUS VARIABLE TRANSMISSION SYSTEM FOR ELECTRIC VEHICLE
CROSS REFERENCE TO RELATED APPLICTIONS
The present application claims priority from Indian Provisional Patent Application No. 202321012244 filed on 23-02-2023, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
The present disclosure generally relates to transmission systems for electric vehicles. Particularly, the present disclosure relates to a transmission system incorporating a planetary gearbox.
BACKGROUND
Generally, transmission systems of electric vehicles play a crucial role in delivering power from an electric motor to a drivetrain of the vehicles. Traditional transmission systems have been designed to accommodate the operational characteristics of internal combustion engines. However, with an increasing popularity of electric vehicles, a noticeable shift has been observed towards developing transmission systems that are optimized for the operation of electric motors such as an ability to provide high torque at low speeds.
Usually, the planetary gearbox is a commonly employed arrangement in mechanical systems as such a gearbox is appreciated for compactness and an ability to provide multiple gear ratios. In a planetary gearbox, a central sun gear receives rotational input, which is then transmitted to multiple gears surrounding the sun gear. The multiple gears in turn engage with a ring gear located along an external periphery thereof. Further, torque and speed distributions are controlled by an interaction between the aforesaid components. However, the conventional use of planetary gearboxes in electric vehicles is associated with limitations, such as, regarding flexibility in output ratios and efficiency of power transfer.
Consequently, while planetary gearboxes offer a compact solution, such gearboxes often lack the necessary flexibility when used in electric vehicles. Other transmission systems are associated with similar issues, such as suboptimal power transmission, excessive bulk, or inadequate adaptability to the wide range of operating conditions encountered by electric vehicles.
In light of the above discussion, there exists an urgent need for solutions that overcome the problems associated with conventional transmission systems for electric vehicles, particularly in terms of providing flexible, efficient, and compact transmission capabilities.
SUMMARY
An object of the present disclosure is to provide a transmission system for an electric vehicle with improved efficiency and adaptability to different driving conditions.
In accordance with the first aspect of the present disclosure, there is provided a transmission system for an electric vehicle. The transmission system comprises a planetary gearbox, which includes a sun gear rotationally located at a centre to receive rotational input, a carrier, and plurality of planetary gears disposed on the carrier. Each planetary gear simultaneously engages with the sun gear to receive the rotational input. Additionally, a ring gear is disposed along the external periphery of the plurality of planetary gears. The transmission system also comprises a shifter that selectively engages the sun gear to provide a first rotational output and the carrier to provide a second rotational output. Such a configuration enables varied power delivery options and improves adaptability to various driving conditions for the vehicle.
The present disclosure provides a transmission system for electric vehicles with increased efficiency and adaptability. Advantageously, the disclosed system allows for precise control over the output rotation, enhancing performance of the vehicle across different speeds and terrains. Furthermore, the transmission system is advantageous in terms of compact design and efficient power transmission, contributing to the overall performance and efficiency of electric vehicles. Additionally, the selective engagement of the shifter with either the sun gear or the carrier optimizes power delivery, improving acceleration and driving dynamics. Moreover, the integration of the planetary gearbox with the shifter ensures a versatile and continuous power transmission, reducing mechanical losses and enhancing the driving experience.
Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
FIG. 1 illustrates a schematic view of a transmission system, in accordance with an embodiment of the present disclosure.
FIG. 2 illustrates another schematic view of the transmission system, in accordance with an embodiment of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognise that other embodiments for carrying out or practising the present disclosure are also possible.
The description set forth below in connection with the appended drawings is intended as a description of certain embodiments of a transmission system for an electric vehicle and is not intended to represent the only forms that may be developed or utilised. The description sets forth the various structures and/or functions in connection with the illustrated embodiments; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimised to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.
The terms “comprise”, “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, system that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system. In other words, one or more elements in a system or apparatus preceded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings and which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
The present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.
As used herein, the terms “electric vehicle” is used to refer to any vehicle having stored electrical energy, including vehicles capable of being charged from an external electrical power source. This may include vehicles having batteries which are exclusively charged from an external power source, as well as hybrid-vehicles which may include batteries capable of being at least partially recharged via an external power source. Additionally, it is to be understood that the term “electric vehicle” as used herein includes electric two-wheeler, electric three-wheeler, electric four-wheeler, electric pickup trucks, electric trucks and so forth.
As used herein, the term “transmission system” refers to a mechanism or assembly in an electric vehicle designed to transmit mechanical power from the motor to the drive axle. This system typically includes various gears and gear-changing mechanisms to adapt the output power for efficient driving under varying conditions.
As used herein, the term “planetary gearbox” is used to describe a gear system consisting of one or more outer gears, or planetary gears, revolving around a central, or sun gear. Typically, this gearbox comprises a set of gears configured to provide various gear ratios between the input and output shafts. The planetary gearbox is associated with an ability to distribute loads across multiple gears.
As used herein, the term “sun gear” refers to the central gear in a planetary gear system. The sun gear receives rotational input from the motor and transmits the rotational motion to the planetary gears that orbit around it. The sun gear is a crucial component in the distribution of power within the gearbox, influencing the overall gear ratio and output speed.
As used herein, the term “carrier” denotes the component within a planetary gearbox that holds one or more planetary gears. The carrier is responsible for the transmission of torque from the planetary gears to the output shaft. It serves as the support and allows the planetary gears to rotate and orbit around the sun gear.
As used herein, the term “planetary gear” relates to the gears mounted on the carrier within a planetary gearbox. These gears mesh with both the sun gear at their centre and the internal teeth of a ring gear on their outer diameter. They are key components in varying the output speed and torque of the transmission system based on their relative motion to the sun gear and ring gear.
As used herein, the term “ring gear” refers to the outer gear or annulus in a planetary gear system. It is characterized by internal teeth that mesh with the planetary gears. The ring gear plays a significant role in determining the gear ratio and can either rotate or be held stationary to alter the output speed and direction of the transmission.
As used herein, the term “shifter” denotes a mechanism within a transmission system that allows the selective engagement of different gears or components. In the context of the transmission system for an electric vehicle, the shifter enables the selective engagement of the sun gear or the carrier to alter the rotational output provided to the drivetrain of the vehicle, thereby adjusting speed and torque according to driving requirements.
Figure 1, in accordance with an embodiment describes a schematic view of a transmission system 100. The transmission system 100 is designed for electric vehicles and consequently, comprises components adapted for optimal performance and efficiency of electric vehicles. The integration of such components offers a solution that is compact, efficient, and highly adaptable for electric vehicles. Further, the transmission system 100 enables optimal power distribution and variable speed control, thus enhancing electric vehicle performance, efficiency, and driving dynamics. Further, the transmission system 100 ensures a balance between acceleration and energy consumption, enabling adaptability to varying demands of electric vehicle operation and providing a superior driving experience.
The transmission system 100 comprises a planetary gearbox 102 comprising a sun gear 104 positioned at a centre of the planetary gearbox 102. The sun gear 104 is a primary recipient of rotational input, such as, from a motor of the electric vehicle. Consequently, the sun gear 104 is crucial in transferring energy from the motor to the transmission system 100. This efficient energy transfer by the sun gear 104 leads to improved vehicle acceleration and responsiveness. Moreover, the central positioning of the sun gear 104 within the planetary gearbox 102 allows for a compact and efficient design, leading to a reduction in the overall size and weight of the transmission system 100, thereby contributing to improved vehicle efficiency and performance as less energy is wasted on moving the components of the transmission system 100. Additionally, the design of the sun gear 104 and an interaction thereof with other gearbox components help in reducing wear and tear, thereby enhancing the longevity and reliability of the transmission system 100. The integration of the sun gear 104 into the planetary gearbox 102 ensures that the electric vehicle can maintain optimal performance across a wide range of operating conditions, ultimately contributing to a better driving experience and lower maintenance costs.
The planetary gearbox 102 further comprises a carrier 106 that acts as a foundational element for plurality of planetary gears 108. These gears are rotationally arranged on the carrier 106 and are designed to simultaneously engage with the sun gear 104. Each planetary gear 108 receives rotational input from the sun gear 104, enabling balanced and efficient power transmission. Such engagement of the plurality of planetary gears 108 with the sun gear 104 results in smooth operation and enhanced driving dynamics, particularly in urban driving scenarios where the transmission system 100 may be required to prioritize torque over speed for improved start-stop efficiency. In an embodiment, the carrier 106 comprises varying sizes or numbers of the planetary gears 108, thus offering a range of gear ratios to accommodate different vehicle types or performance requirements.
Additionally, the planetary gearbox 102 comprises a ring gear 110 situated along the external periphery of the plurality of planetary gears 108. The ring gear 110 plays a significant role in adjusting the output speed and torque, thus enhancing the adaptability of the vehicle to various driving conditions. Further, by interacting with the planetary gears 108, the ring gear 110 enables the transmission system 100 to offer a range of gear ratios, effectively modifying the performance characteristics of the vehicle as needed. Such modification is crucial for optimizing energy consumption and improving the driving experience, such as, when navigating through city traffic, cruising on highways or ascending steep inclines. Furthermore, the ring gear 110 contributes to the overall efficiency of the planetary gearbox 102, allowing for smoother transitions and greater control over vehicle dynamics. The integration of the ring gear 110 with the planetary gears 108 ensure that the electric vehicle can maintain optimal performance under varying loads and speeds, thereby supporting eco-friendly driving practices and extending the operational life of the vehicle.
The transmission system 100 further comprises a shifter 112. The shifter 112 selectively engages with different parts of the planetary gearbox 102, such as the sun gear 104 for a first rotational output and the carrier 106 for a second rotational output, thus allowing for varied driving dynamics, significantly improving control and energy efficiency across different driving scenarios. For example, in city driving, the shifter 112 is engaged with the carrier 106 to enhance torque, aiding in better efficiency during frequent stops and starts. Similarly, for highway driving, the shifter 112 engages the sun gear 104 for maintaining higher speeds efficiently. In an embodiment, the transmission system 100 comprises sensors and control units for automatic adjustment of the shifter 112 based on dynamic vehicle parameters such as speed, acceleration demands, or other driving conditions. Such automatic adjustment further enhances the adaptability and responsiveness of the electric vehicle, optimizing performance for a variety of driving scenarios.
Figure 2, in accordance with an embodiment describes another schematic view of the transmission system 100. As show, the shifter 112 has been moved to engage the carrier 106 instead of the sun gear 104. This adjustment allows the transmission system 100 to alter an associated operational mode, thereby providing a different rotational output suitable for varying driving demands. Further, by engaging the carrier 106, the transmission system 100 is optimized for higher torque at lower speeds, which is beneficial for uphill driving or when starting from a standstill. Such a configuration demonstrates a versatility and adaptability of the transmission system 100, enabling the transmission system 100 to meet diverse requirements and enhance the overall performance of the electric vehicle by providing optimized power and efficiency under different conditions.
In an embodiment, the transmission system 100 the ring gear 110 is maintained in a non-rotational state during the operation of the transmission system 100. Such a configuration ensures that the ring gear 110 acts as a stationary reference point, which in turn influences the gear ratio and the torque output by maintaining a consistent mechanical advantage. The ring gear 110 enables to increase stability and efficiency in power transmission, leading to improved vehicle performance, particularly in scenarios requiring consistent torque delivery, such as uphill driving or heavy-load transportation. For example, in an urban driving scenario, maintaining the ring gear 110 in a non-rotational state enables to enhance vehicle control and efficiency during frequent stops and starts. In an embodiment, the transmission system 100 comprises control mechanisms designed to lock or unlock the rotation of the ring gear 110 based on specific driving conditions or driver preferences, providing a customizable driving experience.
In another embodiment, the carrier 106 comprises multiple hubs. Each planetary gear 108 of the plurality of planetary gears 108 is individually disposed rotationally on a hub of the multiple hubs. Such an arrangement allows for a more even distribution of forces among the planetary gears 108, enhancing the durability and lifespan of the transmission system 100. The aforesaid configuration provides reduced wear and tear on individual planetary gears 108, leading to a more reliable and maintenance-friendly transmission system 110. Additionally, such a setup allows smoother transitions between gears and improved handling under various driving conditions. In an example, the disposition of the planetary gears 108 on the hubs enables heavy-duty electric vehicles to evenly distribute forces, thus enabling to maintain performance and longevity. In an embodiment, the multiple hubs are adjustable in nature enabling modification based on vehicle load or driving conditions, further enhancing the adaptability and efficiency of the transmission system 100.
In an embodiment, the sun gear 104 is associated with a first rotational axis and the carrier 106 being associated with a second rotational axis. The first rotational axis is coaxial with the second rotational axis. This alignment ensures that the sun gear 104 and the carrier 106 rotate around the same central axis, leading to a more compact design and reduced vibrations during operation. The coaxial arrangement enables improved power transmission efficiency and reduced mechanical stress, resulting in a smoother and more energy-efficient driving experience. For example, the coaxial arrangement of the first rotational axis and the second rotational axis enables precision and balance for improving performance and safety of high-speed electric vehicles. In an embodiment, the transmission system 100 incorporates advanced materials or bearing mechanisms that further reduce friction and wear between the coaxially aligned components, enhancing the overall efficiency and durability of the transmission system 100.
In another embodiment, the shifter 112 is connected to a vehicle control unit (VCU) associated with the electric vehicle. This connection enables the VCU to directly control the operation of the shifter 112, enabling automatic or semi-automatic shifting based on various parameters such as vehicle speed, acceleration, and driver input. Such an integration provides enhanced driving comfort, improved fuel efficiency, and optimized performance, as the VCU can make real-time adjustments to transmission settings in response to changing driving conditions. For example, in adaptive cruise control scenarios the VCU adjusts the shifter 112 to optimize fuel efficiency and maintain a constant speed. In an embodiment, the transmission system 100 enables a driver of the electric vehicle to choose between manual and automatic control modes, offering a personalized driving experience while still providing the improved efficiency of VCU-controlled shifting.
In an embodiment, the transmission system 100 further comprises a torque converter. The torque converter allows for a smoother transition between gears by converting and amplifying the torque from the electric motor before the torque reaches the planetary gearbox 102. The incorporation of the torque converter enables enhanced acceleration from a standstill, smoother shifting between gears, and improved vehicle handling, particularly in stop-and-go traffic or on steep inclines. For example, when the transmission system 100 is employed in heavy-duty electric vehicles, the torque converter enables in the handling of heavy loads with better efficiency. In an embodiment, the torque converter enables variable stall speeds, allowing for customization according to different driving styles or load conditions, thereby further enhancing the adaptability of the transmission system 100.
In another embodiment, the geartrain comprises the planetary gearbox 102 and at least one second planetary gearbox. This second planetary gearbox is equipped with a second sun gear located at a centre thereof, a second carrier, multiple second planetary gears rotationally disposed on the second carrier and a second ring gear positioned along an external periphery of the multiple second planetary gears. Each second planetary gear engages with the second sun gear to receive rotational input, thus extending the range of available gear ratios and enhancing the overall performance of the transmission system 100. Such a configuration enables increased flexibility in gear selection, higher efficiency in power transmission, and improved adaptability to different driving conditions. For example, the geartrain comprising multiple gearboxes is advantageous in performance electric vehicles that require a wide range of gear ratios for optimal acceleration and speed. In an embodiment, the transmission system 100 comprises electronically controlled clutches disposed between the multiple gearboxes, allowing for seamless shifting and enhanced efficiency across a wide range of driving scenarios.
In an embodiment, the transmission system 100 comprises a second shifter connected to the second planetary gearbox. This second shifter selectively engages with components of the second planetary gearbox such as the second sun gear to provide a third rotational output and the second carrier 106 to provide a fourth rotational output. This arrangement allows for an expanded range of operational modes and enhances the versatility of the transmission system 100. The multiple rotational outputs enable the electric vehicle to adapt more effectively to varying driving conditions, thus improving traction, efficiency, and overall vehicle performance. In an example, the transmission system 100 is implemented in electric vehicles that face diverse terrain conditions, allowing for optimal power distribution in each scenario. In an embodiment, the transmission system 100 comprises a programmable control unit that automatically adjusts which shifter and components are engaged based on sensor feedback, optimizing performance without driver intervention.
In another embodiment, the third rotational output provided by engaging the second sun gear is different from the first rotational output and the second rotational output. Similarly, the fourth rotational output achieved by engaging the second carrier is different from the first rotational output, the second rotational output and the third rotational output. This differentiation in rotational outputs ensures a broad spectrum of driving dynamics, allowing for precise control over the vehicle speed and torque under various conditions. Consequently, adaptability and performance associated with the vehicle are improved, offering a tailored driving experience through the distinct characteristics of each rotational output.
In an embodiment, the second planetary gearbox is associated with a different gear ratio than the first planetary gearbox 102. This variation in gear ratios between the first planetary gearbox 102 and the second planetary gearbox allows for a wider range of gear combinations and more refined control over the power and speed of the vehicle. The different gear ratios in the second planetary gearbox enhance the ability of the transmission system 100 to adapt to diverse driving requirements, offering improved acceleration, efficiency and responsiveness. Consequently, the different gear rations enable increased flexibility and performance of the transmission system 100 for a broad range of driving conditions and preferences. For example, the different gear ratios can be employed in electric sports cars to maximize performance at different speeds. In an embodiment, the transmission system 100 allows to manually select between different gear ratios for drivers who prefer a more engaged driving experience, further enhancing the versatility of the transmission system 100.
In the description of the present invention, it is also to be noted that, unless otherwise explicitly specified or limited, the terms “disposed,” “mounted,” and “connected” are to be construed broadly, and may for example be fixedly connected, detachably connected, or integrally connected, either mechanically or electrically. They may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Modifications to embodiments and combination of different embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a non- exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural where appropriate.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

,CLAIMS:WE CLAIM:
1. A transmission system (100) for an electric vehicle, the transmission system (100) comprising:
- a planetary gearbox (102) comprising:
- a sun gear (104) rotationally located at a centre of the planetary gearbox (102), wherein the sun gear (104) receives rotational input;
- a carrier (106);
- plurality of planetary gears (108) rotationally disposed on the carrier (106), wherein each planetary gear (108) simultaneously engages with the sun gear (104) to receive the rotational input from the sun gear (104); and
- a ring gear (110) disposed along an external periphery of the plurality of planetary gears (108); and
- a shifter (112) , wherein the shifter (112) selectively engages the:
- sun gear (104) to provide a first rotational output; and
- carrier (106) to provide a second rotational output.
2. The transmission system (100) as claimed in claim 1, wherein the ring gear (110) is maintained in a non-rotational state during operation of the transmission system (100).
3. The transmission system (100) as claimed in claim 1, wherein the carrier (106) comprises multiple hubs and wherein a planetary gear (108) of the plurality of planetary gears (108) is individually disposed rotationally on a hub of the multiple hubs.
4. The transmission system (100) as claimed in claim 1, wherein the sun gear (104) is associated with a first rotational axis and the carrier (106) is associated with a second rotational axis and wherein the first rotational axis is coaxial with the second rotational axis.
5. The transmission system (100) as claimed in claim 1, wherein the shifter (112) is connected to a vehicle control unit (VCU) associated with the electric vehicle.
6. The transmission system (100) as claimed in claim 1, wherein the transmission system (100) comprises a torque converter.
7. The transmission system (100) as claimed in claim 1, wherein the transmission system (100) comprises a geartrain comprising the planetary gearbox (102) and at least one second planetary gearbox (102) and wherein the second planetary gearbox (102) comprises:
- a second sun gear (104) disposed at a centre of the second planetary gearbox (102), wherein the second sun gear (104) receives the rotational input from the planetary gearbox (102);
- a second carrier (106);
- multiple second planetary gears (108) rotationally disposed on the second carrier (106), wherein each second planetary gear (108) engages with the second sun gear (104) to receive the rotational input from the second sun gear (104); and
- a second ring gear (110) disposed along an external periphery of the multiple second planetary gears (108).
8. The transmission system (100) as claimed in claim 7, wherein the transmission system (100) comprises a second shifter (112) connected to the second planetary gearbox (102), wherein the second shifter (112) selectively engages the:
- second sun gear (104) to provide a third rotational output; and
- second carrier (106) to provide a fourth rotational output.
9. The transmission system (100) as claimed in claim 8, wherein the:
- third rotational output is different from the first rotational output and/or the second rotational output; and
- the fourth rotational output is different from the first rotational output, the second rotational output and/or the third rotational output.
10. The transmission system (100) as claimed in claim 7, wherein the second planetary gearbox (102) is associated with a different gear ratio than the planetary gearbox (102).