DESC:CONTINUOUS VARIABLE TRANSMISSION SYSTEM FOR ELECTRIC VEHICLE
CROSS REFERENCE TO RELATED APPLICTIONS
The present application claims priority from Indian Provisional Patent Application No. 202321012853 filed on 25-02-2023, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
The present disclosure generally relates to transmission systems. Particularly, the present disclosure relates to a belt-type continuous variable transmission (CVT) drive.
BACKGROUND
Transmission systems play a critical role in the functionality and efficiency of vehicles, with continuous variable transmission (CVT) systems being a key power transmission system. CVT systems offer the advantage of providing seamless acceleration without the need for manual gear shifting, thereby enhancing the driving experience and fuel/energy efficiency. Traditional CVTs utilize a variety of mechanisms, including belts and pulleys, toroidal, or hydrostatic designs, to achieve variable transmission ratios. Belt-driven CVTs employ a pair of pulleys connected by a belt. The ratio is adjusted by changing the effective contact area of these pulleys to alters the belt's position and, consequently, the transmission ratio.
The belt-type CVT utilizes a belt and pulley to achieve infinite number of gear ratios between maximum and minimum values. Despite various advantages, belt-type CVT systems are confronted with challenges, particularly in terms of the precision and reliability of the gap adjustment mechanism. The effectiveness of the adjustment mechanism is crucial for maintaining the optimal gear ratio and ensuring the longevity of the transmission system. However, issues such as wear and tear of components, mechanical complexity, and response time to adjustments can affect the overall performance and durability of the belt-type CVT. Another issue is the complexity and responsiveness of the gap adjustment mechanism. Traditional systems use hydraulic actuators, springs, etc. to adjust the gap between the pulley discs. These mechanisms can be slow to respond to changes in load or speed, and their complexity can lead to increased manufacturing and maintenance costs.
In light of the above discussion, there exists an urgent need for solutions that overcome the challenges associated with conventional systems and techniques for adjusting the gear ratio in belt-type continuous variable transmission (CVT) drives.
SUMMARY
An object of the present disclosure is to a provide belt-type continuous variable transmission (CVT) drive for an electric vehicle with improved efficiency and adaptability to different driving conditions.
In an aspect, the present disclosure provides a belt-type continuous variable transmission (CVT) drive. The belt-type CVT drive comprises an input pair of discs with a first variable gap therebetween, wherein the input pair of discs receives rotational motion. An output pair of discs structures a second variable gap. A gap adjustment mechanism is simultaneously connected to the input and output pairs of discs, enabling a change in the first variable gap to effect a change in the second variable gap. Additionally, an adjustor connected to a first disc of the input pair enables changing the first variable gap. The modification of the variable gaps allows for accurate control over the transmission ratio, contributing to the efficiency and adaptability of the drive system in various operating conditions. The presence of a gap adjustment mechanism and an adjustor facilitates seamless transition between different transmission ratios, improving the performance and reliability of the belt-type CVT drive.
The present disclosure provides belt-type CVT system to provide smooth, stepless gear ratio changes such that the engine/motor can operate at optimal power range for a variety of speeds, improving the vehicle's performance and fuel/energy efficiency. Advantageously, the disclosed system that fine tune the gap between the input and output disc pairs enables the CVT based on current load and speed of vehicle. Furthermore, the transmission system is advantageous in terms of elimination of jerks felt with traditional stepped gearboxes to enable smoother driving experience, with less noise and vibration, contributing to greater comfort for the vehicle occupants.
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 belt-type continuous variable transmission (CVT) drive comprising several components to function in unison to deliver variable transmission ratios.
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 belt-type continuous variable transmission (CVT) drive of 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 term "continuous variable transmission (CVT) system" or “continuous variable transmission (CVT) drive” refers to a type of transmission that can change seamlessly through an infinite number of effective gear ratios between maximum and minimum values. This system eliminates the need for gear shifts and provides a smooth acceleration experience. The CVT system is designed to improve the efficiency and performance of a vehicle by automatically selecting the optimal gear ratio for any driving condition.
The term "belt-type CVT drive” or “belt-type CVT system” as used throughout the present disclosure relates to a mechanism considered for transmitting power between an input and an output in a vehicle or machinery by utilizing a belt and a pair of variable-diameter pulleys, which can change effective diameters to vary the gear ratio continuously within a range.
As used herein, the term “input pair of discs” denotes a pair of closely positioned discs within a belt-type CVT drive, considered to receive rotational motion from an external source, typically the engine/motor of a vehicle. The input pair of discs receives rotational input from the vehicle's power source, such as an electric motor or internal combustion engine, and transmit received power into the CVT system. By adjusting gap therebetween the input pair of discs allows the CVT to modify the gear ratio.
As used herein, the term “output pair of discs” denotes a pair of discs within the belt-type CVT drive that are positioned space apart from each other. The output pair of discs receives power (through belt or chain) from the input pair of discs and transfer to the vehicle's drivetrain. Through adjustment of gap, transmission ratio can be modified to optimize power output.
As used herein, the term “gap adjustment mechanism” refers to a component within the belt-type CVT drive to alter the variable gaps between the input and output pairs of discs, respectively. The gap adjustment mechanism connected to both pairs of discs and enable regulation of transmission's gear ratios without the need for discrete gear changes.
As used herein, the term “gap” refers to the adjustable space or distance between two facing surfaces of either input discs or putout discs of a CVT drive system. The adjustment of gap (between either input discs or putout discs) directly influences the transmission's gear ratio. By altering the gap size, the CVT can modify the contact diameter for the transmission belt or chain, thereby changing the effective gear ratio and efficient transition across a wide range of speeds and loads.
As used herein, the term “adjustor” refers to a specialized component within the belt-type CVT drive, specifically connected to a first disc of the input pair of discs. The primary function of the adjustor is to facilitate the detailed alteration of the gap between the input pair of discs. The adjustor influences the transmission ratio by adjusting the spacing where the belt or chain engages with the discs. The adjustor operates through mechanical, hydraulic, or electronic means to apply or relieve pressure on the disc, thereby changing position relative to its counterpart and altering the gap therebetween.
Figure 1 describes a belt-type continuous variable transmission (CVT) drive (100), in accordance with embodiment of present disclosure. The belt-type CVT drive (100) comprising the input pair of discs (102), the output pair of discs (104), gap adjustment mechanism (106) and an adjustor (108). The belt-type CVT drive (100) enhances efficiency and reliability in power transmission within drivetrain systems of electric vehicles. In an embodiment, input pair of discs (102), the output pair of discs (104), gap adjustment mechanism (106) and adjustor (108) can provide flexible power transmission system that can achieve power output requirements of the vehicle.
In an embodiment, the input pair of discs (102) receives rotational motion from a power source, such as an engine or electric motor. The input pair of discs (102) comprising a first disc (102a) and second disc (102b) that is disposed space-apart. As the first disc (102a) and second disc (102b) are arranged in space part, the space therebetween creates/defines a first variable gap (d1), which can be adjusted to alter the transmission ratio based on operational condition of vehicle. By allowing continuous variability variable gap (d1), the belt-type CVT drive (100) can achieve multiple gear ratios without the need for manual shifting or the presence of discrete gear stages. Thus, the belt-type CVT drive (100) of present disclosure offers improved fuel/energy efficiency, smoother acceleration, and the ability to maintain optimal engine performance across a wide range of speeds and loads. For example, when the belt-type CVT drive (100) needs to increase the speed of vehicle, the variable gap (d1) between discs (102a and 102b) can adjust to alter transmission ratio to achieve higher output speed. Each of first disc (102a) and second disc (102b) comprises two distinct portions as first portion (i.e., regular portion) and a second portion (i.e., engagement portion) that can interact with the transmission belt or gap adjustment mechanism (106) to facilitate transfer of power to output pair of discs (104).
In another embodiment, the output pair of discs (104) consists of a third disc (104a) and a fourth disc (104b). Similar to the first pair of discs (102), the third disc (104a) and fourth disc (104b) defines a space/second variable gap (d2) therebetween. The second variable gap (d2) can be adjusted to achieve desirable gear ratio to meet current operation requirement (e.g., higher torque or high speed) of vehicle. The second variable gap (d2) can be adjusted in tandem/simultaneously with as per variable gap (d1) to control the output speed and torque delivered to the drivetrain of vehicle. The adjustment of second variable gap (d2) can influence acceleration and cruising efficiency of vehicle. Further, each of third disc (104a) and fourth disc (104b) comprises two distinct segments viz. as first segment (i.e., regular portion) and a second segment (i.e., engagement portion) that can interact with the transmission belt or gap adjustment mechanism (106) to receive power from input pair of discs (102). In another embodiment, a pair of springs (114) can be used to position/maintain second variable gap (d2) by exerting pressure/force on against the third disc (104a) towards fourth disc (104b). The output pair of disc (104) enables transfer of the rotational motion to the driven component, such as the wheels of a vehicle.
In an embodiment, the gap adjustment mechanism (106) can simultaneously connect/interact with each of first disc (102a), second disc (102b), third disc (104a) and fourth disc (104b), through corresponding engagement portion. The gap adjustment mechanism (106) can enable change in first variable gap (d1) to create a change in the second variable gap (d2). Thus, gap adjustment mechanism (106) can enable mirroring of any change in the first variable gap (d1) to second variable gap (d2), allowing for a continuous and smooth variation in transmission ratios. For an instance, as driver presses the accelerator, belt-type CVT drive (100) of present disclosure enable dynamic increment in the first variable gap (d1) between first disc (102a) and second disc (102b), the gap adjustment mechanism (106) simultaneously adjusts second variable gap (d2) between third disc (104a) and fourth disc (104b). The adjustment in second variable gap (d2) and first variable gap (d1) shifts driving belt to a position that increases the transmission ratio, allowing for higher speeds without needing to increase the demand of higher output from power source (e.g., engine/motor).
In an embodiment, the adjustor (108) directly connected to the first disc (102a) and enables alteration in first variable gap (d1) between the input pair of discs (102). The adjustor (108) utilizes a mechanism (e.g., hydraulic actuator, electric motors, or mechanical levers) that can either push or pull the first disc (102a) to vary first variable gap (d1). The adjustor (108) based fine tuning of first variable gap (d1) enables that power transmission can respond swiftly and accurately to changes in driving conditions or power demands. In an aspect, EV (comprising the belt-type CVT drive (100) of present disclosure) comprising motor to delivers rotational motion to the input pair of discs (102). As the vehicle accelerates from a standstill, the adjustor (108) modifies the first variable gap (d1) to a wider setting, decreasing the effective surface area at which the belt engages the input pair of discs (102) to lower gear ratio, maximizing torque output for rapid acceleration. As the vehicle reaches cruising speed, adjustor (108) modifies the first variable gap (d1) to a narrower setting to increase gear ratio to increase speed of the vehicle. In response to transform the first variable gap (d1) to either narrow setting of wider setting, the gap adjustment mechanism (106) mirrors the second variable gaps (d2) as per created first variable gap (d1). In another aspect, during uphill driving, the system detects the need for increased torque to maintain speed. The adjustor (108), responding to inputs from the vehicle control system, adjusts the first variable gap (d1) to decrease the gear ratio, for increasing the engine torque output to the wheels. Thus, belt-type CVT drive (100) of present disclosure can adapt seamlessly to changing driving conditions, offering significant improvements in vehicle performance, energy efficiency, and driver comfort. The dynamic adjustment of gear ratios enables smooth acceleration and deceleration, improving the driving experience.
In another embodiment, first disc first disc (102a) may comprise circular groove that engages with slider arrangement (110) of adjustor (108). Interaction of slider arrangement (110) to circular groove can transfer force onto the first disc (102a) to enable push or pull the first disc (102a) to vary first variable gap (d1). During dynamic driving conditions such as sudden acceleration or deceleration, slider arrangement (110) can quickly adjust the first variable gap (d1) to archive drivetrain requirements.
In an embodiment, the adjustor (108) comprises a motor (112) to cause movement of slider arrangement (110) to change in the first variable gap (d1). The motor (112) (such as an electric motor, stepper motor, hydraulic motor, or pneumatic motor) can provide a controlled and precise force to enable movement to the slider arrangement (110), which can adjust the position of the first disc (102a) relative to the second disc (102b), thereby changing the first variable gap (d1). The slider arrangement (110) can be associated with mechanism that translates the rotational or linear motion generated by the motor (112) into the precise lateral movement required to adjust the first variable gap (d1). The mechanism may consist of rails, guides, or any form of linear actuator that enable smooth movement of the first disc (102a) in a controlled manner. The integration of the motor (112) with the slider arrangement (110) allows for automated and finely tuned adjustments to the first variable gap (d1), facilitating a responsive and adaptable CVT system.
In an embodiment, the motor (112) can be stepper motor that can provide force (based on input from VCU) to alter position of the first disc (102a) to adjust first variable gap (d1) to adapt requirement of powertrain of vehicle based on driving conditions to optimizing the performance of vehicle by continuously adjusting the gear ratio.
Yet another embodiment of the belt-type continuous variable transmission (CVT) drive (100) comprises pair of springs (114) rotatably disposed against the third disc (104b), to automatically adjusting the second variable gap (d2) between the output pair of discs (104). The springs (114) exert a pushing force on the third disc (104a) towards the fourth disc (104a) to counter outward movement of the third disc (104a). Without the force applied by the springs (114), the third disc (104a) can move outwardly due to centrifugal forces generated during operation, especially at higher speeds. The outward movement would increase (in misappropriation of the first variable gap (d1)) the second variable gap (d2) between the output discs (104), leading to slippage of the transmission belt. Belt slippage can result in inefficient power transfer from the motor/engine to the wheels, causing a decrease in vehicle acceleration and responsiveness. By pushing the third disc (104a) towards the fourth disc (104b), the springs enables that the belt remains in optimal contact with the output discs (104), thereby minimizing the risk of slippage. Furthermore, springs enables constant engagement between the belt and the output discs (104) by preventing outward movement of third disc (104a) to enable continues power transmission without interruption.
In an embodiment, where the gap adjustment mechanism (106) comprises, a belt including a first roller received within the first variable gap (d1) and a second roller received within the second variable gap (d2). The first roller and adjustor (108) can manage transmission ratio by adjusting the position of the input discs (102) to control first variable gap (d1). Similarly, the second roller enables the corresponding adjustment of the output pair of discs (104) to regulate second variable gap (d2).
In a subsequent embodiment, a friction-increasing material can be disposed/coat on the internal surfaces of the input pair of discs (102) and output pairs of discs (104). The belt can be positioned between the internal surfaces of the input pair of discs (102) and output pairs of discs (104). The friction-increasing material (such as Kevlar, carbon fibre, ceramic composite, metallic composite, graphite etc.) can improve grip between the internal surfaces and the belt to minimize slippage, improve power transfer efficiency, and smoothen operation power transmission system.
In another embodiment, the belt may comprise multiple stiffening ribs disposed along lateral direction. The stiffening ribs can provide structural support and increase rigidity and resistance to lateral compression and expansion to maintain shape and alignment of belt during operation. The ribs can provide reinforcing effect to belt to maintain consistent contact and force distribution between the belt, input pair of discs (102), and output pair of discs (104).
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 belt-type continuous variable transmission (CVT) drive (100), the belt-
type CVT drive (100) comprising:
- an input pair of discs (102) having a first variable gap (d1) therebetween, wherein the input pair of discs (102) receive rotational motion;
- an output pair of discs (104) having a second variable gap (d2) therebetween;
- a gap adjustment mechanism (106) simultaneously connected to the input pair of discs (102) and the output pair of discs (104), wherein the gap adjustment mechanism (106) enables a change in the first variable gap (d1) to create a change in the second variable gap (d2); and
- an adjustor (108) connected to a first disc (102a) of the input pair of discs (102), wherein the adjustor (108) enables to change the first variable gap (d1).
2. The belt-type CVT drive (100) as claimed in claim 1, wherein:
- the input pair of discs (102) comprise the first disc (102a) and a second disc (102b), wherein the first disc (102a) and the second disc (102b) have the first variable gap (d1) therebetween; and
- the output pair of discs (104) comprise a third disc (104a) and a fourth disc (104b), wherein the third disc (104a) and the fourth disc (104b) have the second variable gap (d2) therebetween;
- wherein the first disc (102a), the second disc (102b), the third disc (104a) and/or the fourth disc (104b) comprises a regular portion and an engagement portion connected to the regular portion.
3. The belt-type CVT drive (100) as claimed in claim 2, wherein the first disc (102a) comprises a circular groove and wherein adjustor (108) comprises a slider arrangement (110) connected to the circular groove.
4. The belt-type CVT drive (100) as claimed in claim 3, wherein the adjustor (108) comprises a motor (112) to cause movement of slider arrangement (110) to change in the first variable gap (d1).
5. The belt-type CVT drive as claimed in claim 4, wherein the motor (112) is a stepper motor.
6. The belt-type CVT drive (100) as claimed in claim 2, comprises a pair of springs (114) rotatably disposed against the third disc (104a) and wherein the pair of springs (114) push of the third disc (104a) towards the fourth disc (104a) to reduce the second variable gap (d2) between the output pair of discs.
7. The belt-type CVT drive (100) as claimed in claim 1, wherein the gap adjustment mechanism (106) comprises a belt and wherein the belt comprises:
- a first roller received within the first variable gap (d1); and
- a second roller received within the second variable gap (d2).
8. The belt-type CVT drive (100) as claimed in claim 7, wherein the belt is disposed between internal surfaces of each of the input pair of discs (102) and the output pair of discs (104) and wherein a friction-increasing material is disposed on the internal surface corresponding to each of the input pair of discs (102) and the output pair of discs (104).
9. The belt-type CVT drive (100) as claimed in claim 7, wherein the belt comprises multiple stiffening ribs disposed along a lateral direction of the belt.