FIELD OF THE INVENTION

[0001] The present invention relates to a hybrid vehicle and more particularly relates to a transmission unit for the hybrid vehicle.

BACKGROUND OF THE INVENTION

[0002] Hybrid vehicles, typically, utilize a Continuously Variable Transmission (CVT) to provide a continuously variable power flow through the transmission. The hybrid vehicles are, typically, equipped with a prime mover and multiple electric motors that can be operated independently or in combination to drive the hybrid vehicle. The principle of operation of the CVT generally includes incorporation of connected frictional members, including belts and friction rotors, to transmit power. The operation also involves continuously changing of at least one of a gear ratio, torque convertors and epicyclical gears with torque transfer devices, incorporated either individually or in combination.

[0003] The hybrid vehicles with the CVT operates in different modes by engaging multiple brakes and clutches in different combinations and thereby controlling the prime mover and the multiple electric motors. Examples of the different modes of the CVT include, but not limited to, series, power- split CVT hybrid, parallel hybrid mode and mechanical drive. However, the said CVT is very complex due to the provision of additional components, such as multiple torque transfer devices, and multiple friction devices, in operability with the CVT, and as such increases the overall hybrid vehicle cost and packaging space requirements. This makes it less suitable for the hybrid vehicles that require simple and compact arrangements. Hence there is a need for a simple, compact CVT transmission unit that integrates various hybrid modes to achieve low fuel consumption during different drive cycles and different modes of the CVT transmission.

BRIEF SUMMARY OF THE INVENTION

[0004] One or more embodiments of the present invention provide a hybrid vehicle. [0005] In one aspect of the invention, a hybrid vehicle is provided. The hybrid vehicle includes a prime mover operably coupled to a set of ground engaging elements of the hybrid vehicle. The hybrid vehicle further includes a first variator operably coupled to the prime mover. The first variator is adapted to operate as one of a motor and a generator. A transmission unit is operably coupled to the prime mover and the first variator. The transmission unit is adapted to transfer power generated by at least one of the prime mover, the first variator, and a combination thereof to the set of ground engaging elements. A second variator is operably coupled to the transmission unit. The second variator is adapted to function as one of a motor and a generator. The hybrid vehicle further includes a controller unit communicably coupled to each of the first variator, the second variator, the transmission unit, and the prime mover. The controller unit is configured to select an operating mode of the hybrid vehicle based on one of, but not limited to, a prime mover speed, an input shaft speed, and a driver power demand via an accelerator pedal and a brake pedal actuation of the hybrid vehicle.

[0006] In another aspect of the invention, a hybrid vehicle is provided. The hybrid vehicle includes a prime mover operably coupled to a set of ground engaging elements of the hybrid vehicle. The hybrid vehicle includes a first variator operably coupled to the prime mover. The first variator is adapted to operate as one of a motor and a generator. The hybrid vehicle includes a first planetary gear set operably coupled to the prime mover and the first variator. The first planetary gear set includes a first member, a second member, and a third member interactively engaged with each other. The hybrid vehicle further includes a second planetary gear set operably coupled to the first planetary gear set. The second planetary gear set includes a first member, a second member, and a third member interactively engaged with each other. A torque transfer device is adapted to operably couple the third member of the first planetary gear set with the second member of the second planetary gear set. Further, a connecting member is adapted to operably couple the second member of the first planetary gear set with the first member of the second planetary gear set. The connecting member aids in transfer of power generated at the second member of the first planetary gear set to the first member of the second planetary gear set. The hybrid vehicle further includes a second variator operably coupled to the first member of the second planetary gear set. The second variator is adapted to operate as one of a motor and a generator. An accumulator is operably coupled to each of the first variator and the second variator. The accumulator is configured to one of store power generated by the first variator and the second variator, and further supply the stored power to each of the first variator and the second variator. Furthermore, the hybrid vehicle includes a controller unit communicably coupled to each of the first and the second variator, the torque transfer device, the friction device, the accumulator, and the prime mover. The controller unit is configured to select an operating mode of the hybrid vehicle based on one of, but not limited to, a prime mover speed, an input shaft speed, a driver power demand via an accelerator pedal and a brake pedal actuation of the hybrid vehicle, and a state of charge of the accumulator.

[0007] In yet another aspect of the invention, a method for operating a hybrid vehicle having a first planetary gear set and a second planetary gear set is provided. Each of the first planetary gear set and the second planetary gear set includes a first member, a second member, and a third member. The method includes coupling a prime mover and a first variator to the first member of the first planetary gear set, and coupling a second variator to the first member of the second planetary gear set. In addition, the method includes coupling the set of ground engaging elements to the third member of the second planetary gear set. The method further includes coupling the third member of the first planetary gear set with the second member of the second planetary gear set, and coupling the second member of the first planetary gear with the first member of the second planetary gear set. The method further includes determining, by a controller unit, a prime mover speed, an input shaft speed, a driver power demand via an accelerator pedal and a brake pedal actuation of the hybrid vehicle, and a state of charge of an accumulator. The method includes selecting, by the controller unit, an operating mode of the hybrid vehicle, wherein the operating mode of the hybrid vehicle is one of a series mode, a Continuously Variable Transmission (CVT) mode with power recirculation, a CVT mode with input power split, and a mechanical drive mode. The method includes selectively one of connecting and disconnecting the third member of the first planetary gear set with the second member of the second planetary gear set by a torque transfer device based on the operating mode selected by the controller unit. The method further includes selectively one of actuating and de-actuating a friction device based on the operating mode selected by the controller unit.

[0008] Other features and aspects of this invention will be apparent from the following description and the accompanying drawings. The features and advantages described in this summary and in the following detailed description are not all-inclusive, and particularly, many additional features and advantages will be apparent to one of ordinary skill in the relevant art, in view of the drawings, specification, and claims hereof. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

[0010] FIG. 1 is a schematic representation of an hybrid vehicle, according to one or more embodiments of the present invention;

[0011] FIG. 2 is a schematic representation of a transmission unit of the hybrid vehicle of FIG. 1, according to one or more embodiments of the present invention;

[0012] FIG. 3 is a schematic representation of the transmission unit of the hybrid vehicle of FIG. 1 operating in a CVT mode with power recirculation, according to one or embodiments of the present invention; [0013] FIG. 4 is a schematic representation of the transmission unit of the hybrid vehicle of FIG. 1 operating in a CVT mode with input power spilt, according to one or embodiments of the present invention;

[0014] FIG. 5 is a schematic representation of the transmission unit of the hybrid vehicle of FIG. 1 operating in a mechanical mode, according to one or embodiments of the present invention; and

[0015] FIG. 6 is a flow chart of a method operating the hybrid vehicle, according to one or more embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0016] Reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts. References to various elements described herein, are made collectively or individually when there may be more than one element of the same type. However, such references are merely exemplary in nature. It may be noted that any reference to elements in the singular may also be construed to relate to the plural and vice-versa without limiting the scope of the invention to the exact number or type of such elements unless set forth explicitly in the appended claims. Moreover, relational terms such as first and second, and the like, may be used to distinguish one entity from the other, without necessarily implying any actual relationship or between such entities.

[0017] FIG. 1 illustrates a schematic representation of an hybrid vehicle 100, according to one or more embodiments of the present invention. The hybrid vehicle 100, as disclosed herein, is any type of vehicle, such as a heavy duty vehicle, a light duty vehicle, a two-wheeler, and a three-wheeler well known in a field of automobile industry without deviating from the scope of the present invention. A prime mover 102 is mounted to a frame of the hybrid vehicle 100. The prime mover 102 is, for example, an internal combustion engine such as a diesel engine, a gasoline engine, a gaseous fuel engine, and any other type of combustion engine known in the art without deviating from the scope of the present invention. The prime mover 102 is adapted to generate power, more specifically mechanical power, in order to operate the hybrid vehicle 100.

[0018] The hybrid vehicle 100 includes a first variator 104 operably coupled to the prime mover 102 of the hybrid vehicle 100 via a shaft 106. More specifically, a first end 108 of the shaft 106 is operably coupled to an input 110 of the first variator 104, and a second end 112 of the shaft 106 is operably coupled to an input shaft 114 of the prime mover 102. In one embodiment, the first variator 104 is operably coupled to the prime mover 102 via one of, but not limited to a gear, a pulley, a belt pulley, a sprocket chain, and a combination thereof. The first variator 104 is adapted to operate as one of a motor and a generator. In the preferred embodiment, the first variator 104 is adapted to operate as one of an electric motor and an electric generator. During operation as the electric motor, the first variator 104 is adapted to generate electric power and aid the prime mover 102 in an operation of the hybrid vehicle 100. During operation as the generator, the first variator 104 is adapted to absorb the mechanical power generated by the prime mover 102. In alternate embodiments, the first variator 104 is adapted to operate as one of a hydraulic pump mechanically associated with a hydraulic motor, and a pneumatic pump associated with a pneumatic motor without deviating from the scope of the present invention.

[0019] A transmission unit 116 is operably coupled to the prime mover 102 and the first variator 104 via the input shaft 114. In an alternate embodiment, the transmission unit 116 is operably coupled to the prime mover 102 and the first variator 104 via one of, but not limited to a gear, a pulley, a belt pulley, a sprocket chain, and a combination thereof. The transmission unit 116 is adapted to transfer the mechanical power generated by one of the prime mover 102, the first variator 104, and a combination thereof to a set of ground engaging elements 132. In addition, the transmission unit 116 includes a differential, in optional combination with additional gearing, such as, from a manual transmission, and an automatic transmission. Construction and arrangement of the transmission unit 116 is explained in detail with reference to FIG. 2.

[0020] The hybrid vehicle 100 further includes a second variator 118 operably coupled to the transmission unit 116 via a shaft 120. More specifically, a first end 124 of the shaft 120 is operably coupled to the transmission unit 116, and a second end 128 of the shaft 120 is operably coupled to an input 126 of the second variator 118. In an alternate embodiment, the second variator 118 is operably coupled to the transmission unit 116 via one of, but not limited to a gear, a pulley, a belt pulley, a sprocket chain, and a combination thereof. The second variator 118 is adapted to operate as one of a motor and a generator. In the preferred embodiment, the second variator 118 is adapted to operate as one of an electric motor and an electric generator. During operation as the electric motor, the second variator 118 is adapted to generate electric power and further aid the prime mover 102 in an operation of the hybrid vehicle 100. During operation as the generator, the second variator 118 is adapted to absorb the mechanical power generated at the transmission unit 116. In alternate embodiments, the second variator 118 is adapted to operate as one of a hydraulic pump mechanically associated with a hydraulic motor, and a pneumatic pump associated with a pneumatic motor without deviating from the scope of the present invention.

[0021] The prime mover 102 is operably coupled to the set of ground engaging elements 132 via the transmission unit 116. More specifically, the prime mover 102 and the first variator 104 are operably coupled to the transmission unit 116 via the input shaft 114, and the set of ground engaging elements 132 is operably coupled to the transmission unit 116 via an output shaft 134. In an alternate embodiment, the prime mover 102 is operably coupled to the set of ground engaging elements 132 via the transmission unit 116 by one of, but not limited to a gear, a pulley, a belt pulley, a sprocket chain, and a combination thereof. Owing to the operable coupling, each of the prime mover 102, the first variator 104, the second variator 118, and a combination thereof is adapted to transfer the mechanical power generated therein to the set of ground engaging elements 132, and thereby propel the hybrid vehicle 100 as per desired by a user of the hybrid vehicle 100. The set of ground engaging elements 132 is one of a set of one or more wheels, tracks, a set of one or more rollers and any other type of ground engaging elements 132 known in the art.

[0022] Each of the first variator 104 and the second variator 118 is further operably coupled to an accumulator 136. As mentioned earlier, the first variator 104 is adapted to absorb the mechanical power generated by the prime mover 102 and the second variator 118 is adapted to absorb the mechanical power generated at the transmission unit 116. On receiving the mechanical power, at least one of the first variator 104, the second variator 118 and a combination thereof is adapted to convert the mechanical power to electric power and store the electric power in the accumulator 136. The accumulator 136 is one of an energy storage device, an energy supply device, and a combination thereof, such as, but not limited to, a battery.

[0023] A controller unit 138 is communicably coupled to each of the prime mover 102, the first variator 104, the transmission unit 116, the second variator 118, and the accumulator 136 via electric control lines 140. The controller unit 138 receives a plurality of input parameters from each of the prime mover 102, the first variator 104, the transmission unit 116, and the second variator 118. The plurality of input parameters is one of, but not limited to, the prime mover 102 speed, an input shaft 106 speed, a driver power demand via an accelerator pedal and a brake pedal actuation of the hybrid vehicle 100, and a state of charge of the accumulator 136. The controller unit 138 is configured to select an operating mode of the hybrid vehicle 100 based on the plurality of input parameters. The operating mode of the hybrid vehicle 100 is one of, but not limited to, a series mode, a Continuously Variable Transmission (CVT) mode with power recirculation, a CVT mode with input power split, and a direct drive mode.

[0024] Referring to FIG. 2, FIG. 2 illustrates a schematic representation of a transmission unit 116 of the hybrid vehicle 100, according to one or more embodiments of the present invention. The transmission unit 116, as disclosed herein, includes a first planetary gear set 202 and a second planetary gear set 204 operably coupled to each other. The first planetary gear set 202 includes a first member 206, a second member 208, and a third member 210 interactively engaged with each other. Each of the first member 206, the second member 208, and the third member 210 of the first planetary gear set 202 is one of a sun gear, a carrier gear, and a ring gear. The carrier gear includes a plurality of planet gears interactively engaged with the sun gear, and the ring gear is interactively engaged with the plurality of planet gears of the carrier gear. [0025] The second planetary gear set 204 includes a first member 212, a second member 214, and, a third member 216 interactively engaged with each other. Each of the first member 212, the second member 214 and the third member 216 of the second planetary gear set 204 is one of a sun gear, a carrier gear, and a ring gear. The carrier gear includes a plurality of planet gears interactively engaged with the sun gear, and the ring gear is interactively engaged with the plurality of planet gears of the carrier gear.

[0026] As mentioned earlier, the prime mover 102 and the first variator 104 are operably coupled to the transmission unit 116 via the input shaft 114. More specifically, the prime mover 102 and the first variator 104 are operably coupled to the first member 206 of the first planetary gear set 202 via the input shaft 114, as shown in FIG. 2. As such, the first member 206 of the first planetary gear set 202 is a driving member of the first planetary gear set 202, owing to which the first member 206 transfers the mechanical power generated by one of the prime mover 102, the first variator 104, and a combination thereof to the second member 208 and the third member 210 of the first planetary gear set 202.

[0027] The first planetary gear set 202 and the second planetary gear set 204 are further operably coupled to each other via a torque transfer device 218. The torque transfer device 218 is a clutch brake combination device adapted to operably couple the third member 210 of the first planetary gear set 202 with the second member 214 of the second planetary gear set 204. Moreover, the torque transfer device 218 aids in transfer of the mechanical power from the first planetary gear set 202 to the second planetary gear set 204.

[0028] The torque transfer device 218 includes a link 220, a contact“A”, a contact“B”, and a contact“C”. One end of the link 220 is fixedly coupled to the contact“C”, and another end of the link 220 is adapted to connect with one of contact“A” and contact“B”. The third member 210 of the first planetary gear set 204 is coupled to the contact“B” of the torque transfer device 218 via a shaft 222. The second member 214 of the second planetary gear set 204 is coupled to the contact“C” of the torque transfer device 218 via a shaft 224. The contact “A” of the torque transfer device 218 is coupled to a gear box casing 225, hereinafter referred to as ground 225. [0029] On connection of the link 220 with the contact“A”, the second member 214 of the second planetary gear set 204 is coupled to the ground 225. As a result, the third member 210 of the first planetary gear set 202 fails to transfer the mechanical power to the second member 214 of the second planetary gear set 204 and is free to rotate.

[0030] On connection of the link 220 with the contact“B”, the third member 210 of the first planetary gear set 202 is operably coupled with the second member 214 of the second planetary gear set 204. As such, there is a transfer of the mechanical power generated at the third member 210 of the first planetary gear set 202 to the second member 214 of the second planetary gear set 204, and thus forming a gear bridge.

[0031] In addition to the coupling between the third member 210 of the first planetary gear set 202 with the second member 214 of the second planetary gear set 204, the first planetary gear set 202 and the second planetary gear set 204 are operably coupled to each via a connecting member 226. The connecting member 226 is adapted to operably couple the second member 208 of the first planetary gear set 202 with the first member 212 of the second planetary gear set 204. Owing to the coupling, the connecting member 226 aids in transfer of the mechanical power generated at the second member 208 of the first planetary gear set 202 to the first member 212 of the second planetary gear set 204. In the preferred embodiment, the connecting member 226 is a shaft. In alternate embodiments, the connecting member 226 is one of, but not limited to a gear, a pulley, a belt pulley, a sprocket chain, and a combination thereof.

[0032] A friction device 228 is further operably coupled to the connecting member 226. The friction device 228 is adapted to selectively ground the mechanical power generated at the second member 208 of the first planetary gear set 202 based on the operating mode selected by the controller unit 138. More specifically, on actuating the friction device 228, the friction device 228 grounds the mechanical power generated at the second member 208 of the first planetary gear set 202. Further, one of actuation and de-actuation of the friction device 226 aids in switching the operation mode of the hybrid vehicle 100. [0033] As mentioned earlier, the second variator 118 is operably coupled to the transmission unit 116. More specifically, the second variator 118 is operably coupled to the first member 212 of the second planetary gear set 204 via the shaft 120. Similarly, the set of ground engaging elements 132 are operably coupled to the third member 216 of the second planetary gear set 204 via the output shaft 134.

[0034] The controller unit 138 is operably coupled to each of the prime mover 102, the first variator 104, the second variator 118, the first torque transfer device 218, the friction device 228, and the accumulator 136 via the electric control lines 140. The controller unit 138 communicates with each of the prime mover 102, the first variator 104, the second variator 118, the first torque transfer device 218, the friction device 228, and the accumulator 136 to receive a plurality of input parameters. The plurality of input parameters is one of, but not limited to, the prime mover 102 speed, the shaft 106 speed, the driver power demand via the accelerator pedal and the brake pedal actuation, and the state of charge of the accumulator 136. Based on the plurality of input parameters, the controller unit 138 is configured to select the operating mode of the hybrid vehicle 100. On selection of the operating mode, the controller unit 138 consequently connects the link 220 with one of the contact“A” and the contact“B” and one of actuates and de-actuates the friction device 228 based on the plurality of input parameters.

[0035] As mentioned earlier, the operating mode of the hybrid vehicle 100 is one of the series mode, the Continuously Variable Transmission (CVT) mode with power recirculation, the CVT mode with input power split, and the direct drive mode. The operation of the embodiment with respect to arrangement of the first planetary gear set 202, second planetary gear set 204, the torque transfer device 218, and the friction device 228 shall be hereon explained in detail to operate the hybrid vehicle 100 in the series mode.

[0036] In the series mode, the controller unit 138 communicates with the torque transfer device 218 to connect the link 220 with the contact“A”. As such, the third member 210 of the first planetary gear set 202 is disconnected from the second member 214 of the second planetary gear set 204. The controller unit 138 further de-actuates the friction device 228 and configures the first variator 104 to operate as the electric generator, and the second variator 118 to operate as the electric motor.

[0037] During operation of the hybrid vehicle 100 in the series mode, the prime mover 102 generates the mechanical power to drive the hybrid vehicle 100. However, as the link 220 within the torque transfer device 218 is connected to the contact“A”, the third member 210 of the first planetary gear set 202 is free to rotate. As a result, the first member 206 of the first planetary gear set 202 fails to transfer power generated by the prime mover 102 to the second member 208 and the third member 210 of the first planetary gear set 202. In addition, the second member 208 of the first planetary gear set 202 fails to transfer power to the first member 212 of the second planetary gear set 204 via the connecting member 226. Thus a torque isolation is achieved between the shaft 106 and the second planetary gear set 204.

[0038] Consequently, the first variator 104 receives the mechanical power generated by the prime mover 102 and converts the mechanical power to electric power, and further stores the electric power within the accumulator 136. The electric power stored in the accumulator 136 by the first variator 104 aids in powering the second variator 118 to generate a gear ratio between the set of ground engaging elements 132 via the output shaft 134, and thereby propel the hybrid vehicle 100.

[0039] FIG. 3 is a schematic representation of the transmission unit 116 of the hybrid vehicle 100 operating in a CVT mode with power recirculation. The illustration of the transmission unit 116 illustrated in FIG.3 is similar to the transmission unit 116 as illustrated in FIG. 2, and thus for the sake of brevity those elements already discussed in FIG. 2 will not be described again in the description for the FIG. 3.

[0040] The hybrid vehicle 100 operates in the CVT mode with power recirculation of the hybrid vehicle 100. The controller unit 138 communicates with the torque transfer device 218 to connect the link 220 with the contact“B”. As such, the third member 210 of the first planetary gear set 202 is connected to the second member 214 of the second planetary gear set 204. The controller unit 138 further de-actuates the friction device 228 and configures the first variator 104 to operate as the electric motor, and the second variator 118 to operate as the electric generator. In the CVT mode with power recirculation, the first variator 104 operates as a parallel source of power to the hybrid vehicle 100.

[0041] During operation of the hybrid vehicle 100 in the CVT mode with power recirculation, the mechanical power generated by each of the prime mover 102 and the first variator 104 is transferred to the first member 206 of the first planetary gear set 202 via the input shaft 116. As the first member 206 of the first planetary gear set 202 is interactively engaged with the second member 208 of the first planetary gear set 202 and in turn interactively engaged with the third member 210 of the first planetary gear set 202, the mechanical power is transferred to each of the second member 208 and the third member 210 of the first planetary gear set 202.

[0042] Moreover, as the link 220 within the torque transfer device 218 is connected to the contact“B”, the torque transfer device 218 aids in transfer of the mechanical power generated at the third member 210 of the first planetary gear set 202 to the second member 214 of the second planetary gear set 204. In addition, the connecting member 226 aids in transfer of the mechanical power generated at the second member 208 of the first planetary gear set 202 to the first member 212 of the second planetary gear set 204 resulting in rotation of the first member 212 of the second planetary gear set 204 with a resultant speed. In addition, as the second variator 118 is configured to operate as the electric generator, the second variator 118 receives the mechanical power transferred to the first member 212 of the second planetary gear set 202. The second variator 118 converts the mechanical power to electric power and stores the resultant electric power in the accumulator 136. The electric power thus stored is used for driving the first variator 104.

[0043] The first member 212 of the second planetary gear set 204 is interactively engaged with the second member 214 of the second planetary gear set 204 and in turn interactively engaged with the third member 216 of the second planetary gear set 204. Thus, the mechanical power received at the first member 212 of the second planetary gear set 204 is transferred to each of the second member 214 and the third member 216 of the second planetary gear set 204. As mentioned earlier, the set of ground engaging elements 132 is operably coupled to the third member 216 of the second planetary gear set 204 via the output shaft 134. As such, transfer of power from combination of the prime mover 102 and the first variator 104 to the set of ground engaging elements 132 aids in operating the hybrid vehicle 100 in the CVT mode with power recirculation.

[0044] FIG. 4 is a schematic representation of the transmission unit 116 of the hybrid vehicle 100 operating in a CVT mode with input power spilt, according to one or embodiments of the present invention. The illustration of the transmission unit 116 illustrated in the FIG. 4 is similar to the transmission unit 116 depicted in FIG. 2, and thus for the sake of brevity those elements already discussed in FIG. 2 will not be described again for the description of the FIG. 4.

[0045] As a speed of the set of the ground engaging elements 104 increases to a threshold speed limit, a direction of rotation of the first variator 104 reverses, resulting in switching of the mode of operation of the hybrid vehicle 100 from the CVT mode with power recirculation to the CVT mode with input power split. Moreover, on reaching the threshold speed limit, the first variator 104 operates as the electric generator and the second variator 118 operates as the electric motor. The threshold limit is defined based on the prime mover 102 specification of the hybrid vehicle 100.

[0046] During operation of the hybrid vehicle 100 in the CVT mode with input power split, the mechanical power generated by the prime mover 102 is transferred to each of the first variator 118 and the first planetary gear set 202 via the input shaft 116. The first variator 104 receives the mechanical power and converts the mechanical power to electric power. The resultant electric power is stored in the accumulator 136, which is in turn used by the second variator 104 to operate as the electric motor and operate as the parallel source of power for driving the hybrid vehicle 100.

[0047] As the first member 206 of the first planetary gear set 202 is interactively engaged with the second member 208 of the first planetary gear set 202 and in turn interactively engaged with the third member 210 of the first planetary gear set 202, the power is transferred to each of the second member 208 and the third member 210 of the first planetary gear set 202. [0048] As the link 220 within the torque transfer device 218 is connected to the contact“B”, the torque transfer device 218 aids in transfer of the mechanical power generated at the third member 210 of the first planetary gear set 202 to the second member 214 of the second planetary gear set 204. In addition, the connecting member 226 aids in transfer of the mechanical power generated at the second member 208 of the first planetary gear set 202 to the first member 212 of the second planetary gear set 204 resulting in rotation of the first member 212 of the second planetary gear set 204 at a resultant speed. Moreover, the first member 212 of the second planetary gear set 204 receives mechanical power from the second variator 118.

[0049] The first member 212 of the second planetary gear set 204 is interactively engaged with the second member 214 of the second planetary gear set 204 and in turn interactively engaged with the third member 216 of the second planetary gear set 204. Thus, the mechanical power received from the first planetary gear set 202 and the second variator 118 is transferred to each of the second member 214 and the third member 216 of the second planetary gear set 204. As mentioned earlier, the set of ground engaging elements 132 is operably coupled to the third member 216 of the second planetary gear set 204 via the output shaft 134. As such, a total power output from each of the first planetary gear set 202 and the second planetary gear set 204 drives the set of ground engaging elements 132 via the output shaft 134 in the CVT mode with power recirculation.

[0050] FIG. 5 is a schematic representation of the transmission unit 116 of the hybrid vehicle 100 operating in the direct drive mode, according to one or embodiments of the present invention. The illustration of the transmission unit 116 illustrated in FIG. 5 is similar to the transmission unit 116 illustrated in FIG. 2, and thus for the sake of brevity those elements already discussed in FIG. 2 will not be described again for the description of FIG. 5.

[0051] In the direct drive mode, the controller unit 138 communicates with the torque transfer device 218 to connect the link 220 with the contact“B”. As such, the third member 210 of the first planetary gear set 202 is connected to the second member 214 of the second planetary gear set 204. The controller unit 138 further actuates the friction device 228 and configures the first variator 104 to operate as one of an electric motor and an electric generator. In an alternate embodiment, the first variator 104 is configured to remain idle. The controller unit 138 further configures the second variator 118 to remain idle.

[0052] During operation of the hybrid vehicle 100 in the direct drive mode, the mechanical power generated by the prime mover 102 is transferred to the first member 206 of the first planetary gear set 202 via the input shaft 116. As the first member 206 of the first planetary gear set 202 is interactively engaged with the second member 208 of the first planetary gear set 202 and in turn interactively engaged with the third member 210 of the first planetary gear set 202, the mechanical power is transferred to each of the second member 208 and the third member 210 of the first planetary gear set 202.

[0053] Owing to the actuation of the friction device 228, there is no transfer of power between the second member 208 of the first planetary gear set 202 and the first member 212 of the second planetary gear set 204. As the link 220 within the torque transfer device 218 is connected to the contact“B”, the torque transfer device 218 aids in transfer of the mechanical power generated at the third member 210 of the first planetary gear set 202 to the second member 214 of the second planetary gear set 204.

[0054] The second member 214 of the second planetary gear set 204 receives the mechanical power from the third member 210 of the first planetary gear set 202. As the third member 216 of the second planetary gear set 204 is interactively engaged with the second member 214 of the second planetary gear set 204, the mechanical power is transferred to the third member 216 of the second planetary gear set 204. The third member 216 of the second planetary gear set 204, in turn drives the set of ground engaging elements 132 via the output shaft 134.

[0055] FIG. 6 is a flow chart of a method 600 operating the hybrid vehicle 100, according to one or more embodiments of the present invention. The hybrid vehicle 100 includes the first planetary gear set 202 and the second planetary gear set 204. The first planetary gear set 202 includes the first member 206, the second member 208, and the third member 210 interactively engaged with each other. The second planetary gear set 204 includes the first member 212, the second member 214, and the third member 216 interactively engaged with each other.

[0056] At step 602, the method 600 includes coupling the prime mover 102 and the first variator 104 to the first member 206 of the first planetary gear set 202. The prime mover 102 and the first variator 104 are operably coupled to the first member 206 of the first planetary gear set 202 via the input shaft 114.

[0057] At step 604, the method 600 includes coupling the second variator 118 to the first member 212 of the second planetary gear set 204. The second variator 118 is operably coupled to the first member 212 of the second planetary gear set 204 via the shaft 120. The first end 124 of the shaft 120 is operably coupled to the transmission unit 116, and the second end 128 of the shaft 120 is operably coupled to the input 126 of the second variator 118. In an alternate embodiment, the second variator 118 is operably coupled to the transmission unit 116 via one of, but not limited to a gear, a pulley, a belt pulley, a sprocket chain, and a combination thereof.

[0058] At step 606, the method 600 includes coupling the third member 210 of the first planetary gear set 202 with the second member 214 of the second planetary gear set 204 via the torque transfer device 218. The torque transfer device 218 includes the link 220, the contact“A”, the contact“B”, and the contact“C”. The third member 210 of the first planetary gear set 204 is coupled to the contact“B” of the torque transfer device 218 via the shaft 222. The second member 214 of the second planetary gear set 204 is coupled to the contact“C” of the torque transfer device 218 via the shaft 224. The contact“A” of the torque transfer device 218 is coupled to the gear box casing, hereinafter referred to as ground 225. One end of the link 220 is fixedly coupled to the contact“C”, and another end of the link 220 is adapted to connect with one of contact“A” and contact“B”. The step 606 of the method 600, further includes operably coupling the set of ground engaging elements 132 to the third member 216 of the second planetary gear set 204 via the output shaft 134.

[0059] At step 608, the method 600 includes coupling the second member 208 of the first planetary gear set 202 with the first member 212 of the second planetary gear set 204 via the connecting member 226. The connecting member 226 is adapted to operably couple the second member 208 of the first planetary gear set 202 with the first member 212 of the second planetary gear set 204. Owing to the coupling, the connecting member 226 aids in transfer of the mechanical power generated at the second member 208 of the first planetary gear set 202 to the first member 212 of the second planetary gear set 204. The friction device 228 is further operably coupled to the connecting member 226. The friction device 228 is adapted to selectively ground the mechanical power generated at the second member 208 of the first planetary gear set 202.

[0060] At step 610, the method 600 includes determining, by the controller unit 138, the prime mover 102 speed, the shaft 106 speed, the driver power demand via the accelerator pedal and the brake pedal actuation, and the state of charge of the accumulator 136. The controller unit 138 is communicably coupled to each of the prime mover 102, the first variator 104, the second variator 118, the first torque transfer device 218, the friction device 228, and the accumulator 136 via the electric control lines 140 to receive the plurality of input parameters. Based on the plurality of input parameters, the controller unit 138 is configured to select the operating mode of the hybrid vehicle 100.

[0061] At step 612, the method 600 includes selecting, by the controller unit 138, the operating mode of the hybrid vehicle 100. The operating mode of the hybrid vehicle 100 is one of the series mode, the CVT mode with power recirculation, the CVT mode with input power split, and mechanical drive mode.

[0062] At step 614, the method 600 includes selectively one of connecting and disconnecting the third member 210 of the first planetary gear set 202 with the second member 214 of the second planetary gear set 204 by the torque transfer device 218. The controller unit 138 is configured to one of connect the link 220 with one of the contact“A” and the contact“B” based on the operating mode selected by the controller unit 138. In the series mode, the controller unit 138 is configured to connect the link 220 with the contact“A”. In the CVT mode with power recirculation and the CVT mode with input power split, the controller unit 138 is configured to connect the link 220 with the contact“B”. In the mechanical drive mode, the controller unit 138 is configured connect the link 220 with the contact“B”.

[0063] At step 616, the method includes selectively one of actuating and de- actuating a friction device 228 by the controller unit 138 to one of actuate and de- actuate the friction device 228 based on the plurality of input parameters. In the series mode, the CVT mode with power recirculation, and the CVT mode with input power split the controller unit 138 is configured to de-actuate the friction device 228. In the mechanical drive mode, the controller unit 138 is configured to actuate the friction device and as such ground the transfer of the mechanical power generated at the second member of the first planetary gear set.

[0064] Various embodiments disclosed herein are to be taken in the illustrative and explanatory sense, and should in no way be construed as limiting of the present invention.

[0065] While aspects of the present invention have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present invention as determined based upon the claims and any equivalents thereof.