Description:FIELD OF THE INVENTION
[0001] Present invention relates to a hybrid electric vehicle. More particularly, the present invention relates to a Plug-in Hybrid Electric Drive System (HDS) for a four wheeler vehicle.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] One of the greatest challenges being faced by human race today is undoubtedly the climate change and its potentially catastrophic consequences for humanity. The ever rising greenhouse gas emissions coupled with massive urbanisation trends create a further challenge where large scale migration to urban areas is creating several high density population clusters that require tremendous resources for survival such as round the clock availability of utilities, products and services to support such urban lifestyle. As a consequence, one of the highest contributors to global greenhouse gas emissions is transportation sector, responsible for nearly quarter of greenhouse gas emissions every year. The urban vehicular emissions not only affect the global temperature rise and the climate, but also the health of the urban populations as they inhale those harmful vehicular emissions that create health hazards including early deaths and COPD (chronic obstructive pulmonary disorders).
[0004] There has been a strong scientific evidence and record of such health hazards and ailments which need to be addressed with the sense of urgency, by providing more workable solutions for sustainable mobility which reduces the quantum of harmful emissions. At the same time, the consumers of automobile sector are used to certain conveniences with respect to ease of fuelling, long range on a full fuel tank, as well as certain driving features which can’t be taken away from them in an instant by switching to non-IC engine vehicles such as fully electric vehicles, which are short on features and conveniences keeping in mind 30 the mass affordability factor. The fully electric vehicles have several shortcomings such as long recharge times, inconvenience of not having adequate charging facilities, range anxiety for drivers and passengers as a result of relatively short range on a single charge, load carrying limitations in steep uphill terrains, etc.
[0005] Therefore, there is a need to first migrate to an intermittent stage of hybrid electric mobility solution whereby all shortcomings of a full electric vehicle as mentioned above can be effectively addressed; and during urban and large parts of inter city transportation routes, the vehicles can operate on fully electric mode easily. This will create at least 80% more green miles by consumers switching to intelligent plug in hybrid electric vehicles and operating in zero emissions mode for most of the miles driven. The additional benefits of re-cycling and up-cycling of existing IC engine vehicle parts will reduce the greenhouse emissions further by extending the life of in-use products in the integrated supply chain. On a national level, the resulting savings of imported fuel and the consequential benefits to Indian economy is certainly a huge advantage and makes a strong case for economic stimulus to be given by the Government for faster and broader adoption of such sustainable mobility solutions, such as the one which is described in this application. Patent document US2010048338 discloses a EPPV transmission hybrid electric drive system using a combination of power sources and including a first clutch and a second clutch for changing the mode of the transmission from a high mode to a low mode and vice versa.
[0006] There is, therefore, a need in the art to develop a hybrid electric drive system for vehicles that results in a less polluting, eco-friendly, and low operational cost plug-in hybrid electric four wheeler.

OBJECTS OF THE PRESENT DISCLOSURE
[0007] Some of the objects of the present disclosure, which at least one embodiment herein satisfies are as listed herein below.
[0008] It is an object of the present invention to provide a fast and simple method to convert IC engine driven four-wheeler vehicle architectures to a plug-in hybrid electric four-wheeler.
[0009] It is an object of the present invention to provide a hybrid electric drive for a driven axle of four wheelers by using a hybrid electric drive system (interchangeably known as Hybrid Drive System (HDS)) that enables conversion of the IC engine driven four-wheeler vehicles to a plug-in hybrid electric four-wheeler.
[0010] It is another object of the present invention to provide a hybrid electric drive system that allows a user to control the mode of operation of the vehicle in specifically mandated zero vehicular pollution zones in urban areas.
[0011] It is another object of the present invention to provide a hybrid electric drive system that can be coupled to any of a front axle or a rear axle of the vehicle.
[0012] It is another object of the present invention to simplify the installation of an electric drive assembly by providing an integrated assembly including the electric motor and control mechanism.
[0013] It is another object of the present invention to have a user-friendly mode controller that can be operated from the driver’s seat or using a programmable logic.
[0014] It is another object of the present invention to combine the IC engine and electric drive and synchronize the torque addition in a way to utilize the specific torque-speed characteristics of the IC engine and the electric motor to enable a highly efficient and low emissions and low fuel consumption operation of the combined powertrain.

SUMMARY
[0015] Present disclosure relates to a hybrid electric vehicle. More particularly, the present invention relates to a Plug-in Hybrid Electric Drive System (HDS) for a four wheeler vehicle. Specifically, the present disclosure provides a hybrid electric drive system that can convert a conventional IC engine driven vehicle to a hybrid electric vehicle.
[0016] In an aspect, the proposed hybrid electric drive system for a vehicle includes an electric motor and an epicyclic gear system. The hybrid electric drive system is configured between an Internal Combustion engine of the vehicle and a differential of an axle of the vehicle. The hybrid electric drive system performs a dual role of allowing drive from any or both of the IC engine and the electric motor to be transmitted, individually or adding the drive from the two, seamlessly to wheels of the corresponding axle of the vehicle, thereby allowing driving the vehicle in three different driving modes, i.e., an electric driving mode, an IC engine driving mode, an a combined driving mode.
[0017] In an aspect, the hybrid electric drive system includes a pair of levers that move to different positions to enable different driving modes. The hybrid electric drive system further includes a cam and solenoid based control mechanism to move the pair of levers to different positions, based on signals, to enable different driving modes.
[0018] In an embodiment, the cam and solenoid based control mechanism may include a mode shifter mounted on a mode shift axle; a pair of eccentric cam bushes mounted on the mode shift axle; and a pair of solenoids coupled to the mode shifter to operate the mode shifter. The pair of levers may be mounted on the eccentric cam bushes such that when the solenoids are actuated, the resultant rotation of the mode shift axle causes the levers to move to different positions to enable different driving modes.
[0019] In an embodiment, the control mechanism may further include a programmable logic operatively coupled to the pair of solenoids to provide the signals to actuate the pair of solenoids, thereby enabling change of the driving modes from a driver’s seat of the vehicle.
[0020] In an embodiment, the axle may be any of a front axle or a rear axle of the vehicle. The hybrid electric drive system may be coupled to the rear axle through a propeller shaft, and to the front axle directly to a differential of a transaxle unit of the vehicle.
[0021] In an embodiment, the epicyclic gear system may allow output to be taken from a sun gear and input to be given to at least one of planet carrier or a ring gear (406). Power from both the IC engine assembly and the hybrid electric drive system may be transmitted to the corresponding axle. The power from both the IC engine assembly and the electric motor may be transmitted to the sun gear such that the sun gear transmits the power to the corresponding axle.
[0022] In an embodiment, the hybrid electric drive system may include a first pinion gear that locks and unlocks the planet carrier, and a third pinion gear that locks and unlocks the ring gear. The first and third pinion gears may be mounted on the pair of levers that move in different positions to enable locking or unlocking of at least one of the planet carrier and the ring gear for enabling different driving modes.
[0023] In an embodiment, the hybrid electric drive system may further include a second pinion gear to transmit power from the electric motor to the ring gear.
[0024] In an embodiment, for the electric or IC engine mode, the levers may be moved to a position such that the planet carrier is unlocked, the electric motor power is transmitted to the planet carrier through a series of pinion gears, and the ring gear is locked by the third pinion to enable the electric mode or IC engine mode respectively of the hybrid electric drive system.
[0025] In an embodiment, for the combined mode, the levers may be moved to a position such that the planet carrier is unlocked, the motor power is transmitted to the planet carrier, and the ring gear is unlocked, Unlocking of the ring gear allows the sun gear to adjust to the power being transmitted from both the IC engine and the electric motor.
[0026] In an embodiment, a combined accelerator is provided with a configurable phase lag that allows, during the combined mode, the electric motor to speed up earlier than the IC engine, which allows a high initial starting torque of the electric power-train.
[0027] In an embodiment, for reverse operation in the electric mode, the levers may be moved to positions so that the planet carrier is locked by pinion, and electric motor power is transmitted to the ring gear via compound pinion gear causing the sun gear to rotate in opposite direction to that of the ring gear, thereby reversing the rotation.
[0028] In an embodiment, locking of the planet carrier and providing electric motor power to the ring gear causes the sun gear to provide the output torque to the drive shaft to rotate in a direction opposite to the motor rotation.
[0029] In an embodiment, during regeneration, mechanical power may be transferred from the sun gear to the planet carrier with the ring gear being locked or unlocked results in different levels of regeneration to allow a battery pack to be recharged depending on the state of charge.
[0030] In an embodiment, the vehicle comprises a fuelling system having a hydrogen fuel cells stack for providing electrical energy to operate the electric motor. The hydrogen fuel cells stack, a liquid hydrogen tank and a battery pack may be mounted on chassis of the vehicle under its body.
[0031] In an embodiment, electrical energy to operate the electric motor may be provided by an arrangement of ultra-capacitors.
[0032] An aspect of the present disclosure relates to a vehicle comprising the disclosed hybrid electric drive system.
[0033] Various objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like features.
[0034] Within the scope of this application it is expressly envisaged that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.

BRIEF DESCRIPTION OF DRAWINGS
[0035] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. The diagrams are for illustration only, which thus is not a limitation of the present disclosure.
[0036] FIG. 1A illustrates an exemplary implementation of an electric mode in a vehicle, in accordance with an embodiment of the present disclosure.
[0037] FIG. 1B illustrates an exemplary implementation of an engine mode in the vehicle, in accordance with an embodiment of the present disclosure.
[0038] FIG. 1C illustrates an exemplary implementation of a combined mode in the vehicle, in accordance with an embodiment of the present disclosure.
[0039] FIG. 1D illustrates an exemplary implementation of an electric reverse mode in the vehicle, in accordance with an embodiment of the present disclosure.
[0040] FIG. 1E illustrates an exemplary implementation of a regeneration mode in the vehicle, in accordance with an embodiment of the present disclosure.
[0041] FIG. 2A illustrates an exemplary general arrangement of the vehicle from passenger side, in accordance with an embodiment of the present disclosure.
[0042] FIG. 2B illustrates an exemplary general arrangement of the vehicle from driver side, in accordance with an embodiment of the present disclosure.
[0043] FIG. 2C illustrates an exemplary general arrangement of the vehicle from under side, in accordance with an embodiment of the present disclosure.
[0044] FIG. 3 illustrates an exemplary architecture of Electric Drive Assembly in the vehicle, in accordance with an embodiment of the present disclosure.
[0045] FIG. 4A illustrates an exemplary view of the epicyclic gear system from engine side, in accordance with an embodiment of the present disclosure.
[0046] FIG. 4B illustrates an exemplary view of the epicyclic gear system from motor side, in accordance with an embodiment of the present disclosure.
[0047] FIG. 5A illustrates an exemplary view of the mode controller when in single mode, in accordance with an embodiment of the present disclosure.
[0048] FIG. 5B illustrates an exemplary view of a mode controller when in combined mode, in accordance with an embodiment of the present disclosure.
[0049] FIG. 5C illustrates an exemplary view of the the mode controller when in electric reverse mode, in accordance with an embodiment of the present disclosure.
[0050] FIG. 6 illustrates an exemplary schematic diagram of the combined electro-mechanical accelerator of the vehicle, in accordance with an embodiment of the present disclosure.
[0051] FIG. 7A illustrates an exemplary graphical representation of the vehicle with resultant torque-speed characteristics, in accordance with an embodiment of the present disclosure.
[0052] FIG. 7B illustrates an exemplary graphical representation of the vehicle with resultant torque-speed characteristics under various drive cycles, in accordance with an embodiment of the present disclosure.
[0053] FIG. 7C illustrates an exemplary graphical representation of the vehicle with resultant reduction in IC engine usage, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0054] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0055] In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent to one skilled in the art that embodiments of the present invention may be practiced without some of these specific details.
[0056] Embodiments of the present invention include various steps, which will be described below. The steps may be performed by hardware components or may be embodied in machine-executable instructions, which may be used to cause a general-purpose or special-purpose processor programmed with the instructions to perform the steps. Alternatively, steps may be performed by a combination of hardware, software, and firmware and/or by human operators.
[0057] Various methods described herein may be practiced by combining one or more machine-readable storage media containing the code according to the present invention with appropriate standard computer hardware to execute the code contained therein. An apparatus for practicing various embodiments of the present invention may involve one or more computers (or one or more processors within a single computer) and storage systems containing or having network access to computer program(s) coded in accordance with various methods described herein, and the method steps of the invention could be accomplished by modules, routines, subroutines, or subparts of a computer program product.
[0058] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[0059] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0060] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. These exemplary embodiments are provided only for illustrative purposes and so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those of ordinary skill in the art. The invention disclosed may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Moreover, all statements herein reciting embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). Also, the terminology and phraseology used is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed. For purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail so as not to unnecessarily obscure the present invention.
[0061] Thus, for example, it will be appreciated by those of ordinary skill in the art that the diagrams, schematics, illustrations, and the like represent conceptual views or processes illustrating systems and methods embodying this invention. The functions of the various elements shown in the figures may be provided through the use of dedicated hardware as well as hardware capable of executing associated software. Similarly, any switches shown in the figures are conceptual only. Their function may be carried out through the operation of program logic, through dedicated logic, through the interaction of program control and dedicated logic, or even manually, the particular technique being selectable by the entity implementing this invention. Those of ordinary skill in the art further understand that the exemplary hardware, software, processes, methods, and/or operating systems described herein are for illustrative purposes and, thus, are not intended to be limited to any particular named element.
[0062] Systems depicted in some of the figures may be provided in various configurations. In some embodiments, the systems may be configured as a distributed system where one or more components of the system are distributed across one or more networks in a cloud computing system.
[0063] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0064] All methods described herein may be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0065] Various terms as used herein. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0066] Embodiments described herein relate to a hybrid electric vehicle. More particularly, the present disclosure provides a Plug-in Hybrid Electric Drive System (HDS) for a four wheeler vehicle.
[0067] According to an aspect of the present disclosure, the proposed hybrid electric drive system comprises an electric motor and an epicyclic gear system. The hybrid electric drive system can be coupled between an IC power pack, comprising an IC engine and a gear box (hereinafter also referred simply as IC engine), and an axle, such as a front axle, or a rear axle, of the vehicle. In case of rear axle, the hybrid electric drive system can be coupled to a differential of the rear axle through a propeller shaft; and in case of the front axle, the hybrid electric drive system can located within a transaxle unit of the vehicle and directly coupled through the common final drive shaft to a differential of the transaxle.
[0068] According to an embodiment of the present disclosure, the hybrid electric drive system can perform dual role of allowing drive from each powertrain, i.e., the IC engine and the electric motor, to be transmitted individually to the respective axle, or by adding the drive from each powertrain together and seamlessly transmitting to the wheels of the axle.
[0069] According to an embodiment of the present disclosure, the hybrid electric drive system can enable driving independently in either an electric mode, an IC engine mode, or a combined mode.
[0070] According to an embodiment of the present disclosure, the epicyclic gear system can allow output to be taken from a sun gear and input to be given to at least one planet carrier or ring gear. The power from both the IC engine and the electric motor is transmitted to the sun gear, which transmits the power to the common drive shaft.
[0071] According to an embodiment of the present disclosure, the epicyclic gear system and the electric motor can be located using mountings as a single module on the transaxle unit of the vehicle in case of front wheel drive vehicles or can be mounted on the chassis frame of the vehicle in case of rear wheel drive vehicles between the IC engine gearbox and the final drive.
[0072] According to an embodiment of the present disclosure, the hybrid electric drive system can comprise a cam and solenoid mechanism that controls the operation of a plurality of vehicle drive modes by locking elements of the epicyclic gear system. A set of solenoid valves operates the mode shifter, the mode shifter is mounted to the mode shift axle that has eccentric cam bushes mounted on it, to these eccentric cam bushes are attached the control levers. The control levers lock and unlock the elements of the epicyclic gear system.
[0073] According to an embodiment of the present disclosure, the hybrid electric drive system can comprise a first pinion gear, a second pinion gear, and a third pinion gear. The first pinion gear can lock and unlock the planet carrier, and the second pinion gear can transmit motor power to ring gear. Further, the third pinion gear can lock and unlock the ring gear, where the first, second, and third pinion gears are mounted on levers that move in different positions to enable three different driving modes.
[0074] According to an embodiment of the present disclosure, an electric or IC engine mode can be implemented when the levers are moved in a position so that the planet carrier can be unlocked. Further, the electric motor power can be transmitted to the planet carrier through a series of pinion gears, and the ring gear can be locked by pinion such that depending on the switch being on, the electric mode or IC engine mode respectively can be enabled.
[0075] According to an embodiment of the present disclosure, a combined mode can be implemented when the lever is moved in a position so that the planet carrier can be unlocked. Further, the motor power can be transmitted to the planet carrier, and the ring gear can be unlocked such that unlocking of the ring gear allows the sun gear to adjust to the power being transmitted from both IC Engine and electric motor.
[0076] According to an embodiment of the present disclosure, a combined accelerator of the vehicle designed with a configurable phase lag allows the electric motor to speed up earlier than the IC engine to take advantage of the high initial starting torque of the electric power-train while being driven in the combined mode.
[0077] According to an embodiment of the present disclosure, when the vehicle is in reverse electric mode, the levers are moved in a position so that the planet carrier can be locked by pinion, and electric motor power can be transmitted to the ring gear via compound pinion gear causing the sun gear to spin in opposite direction to that of the ring gear thereby reversing the motion.
[0078] According to an embodiment of the present disclosure, locking of the planet carrier and providing electric motor power to the ring gear causes the sun gear to provide the output torque to the drive shaft to spin in a direction opposite to the motor rotation.
[0079] According to an embodiment of the present disclosure, during regeneration, mechanical power can be transferred from sun gear to planet carrier with the ring gear locked or unlocked results in different levels of regeneration to allow the battery pack to be recharged depending on the state of charge.
[0080] According to an embodiment of the present disclosure, the battery pack of the vehicle is placed on chassis in the cargo compartment of the vehicle.
[0081] According to an embodiment of the present disclosure, a microprocessor operated system can control the operation of one or more modes by locking different elements of the epicyclic gear system. A set of solenoid valves operates the mode shifter as per desired signal via the microprocessor, the mode shifter is mounted to the mode shift axel that has eccentric cam bushes mounted on it, to these eccentric cam bushes are attached the control levers. The mode shifter thus operates the levers. The epicyclic gear system can comprise a first pinion gear, a second pinion gear, and a third pinion gear. The first pinion gear can lock and unlock the planet carrier, the third pinion gear can lock and unlock ring gear, and the second pinion gear can transmit motor power to the ring gear. These pinions are mounted on the levers that move in different positions to enable the three different driving modes.
[0082] According to an embodiment of the present disclosure, the vehicle can comprise an optional fuelling system of hydrogen fuel cells stack providing the electrical energy to operate the electric motor. The hydrogen fuel cells stack, the liquid hydrogen tank and the battery pack of the vehicle can be mounted on chassis in the cargo compartment of the vehicle.
[0083] According to an embodiment of the present disclosure, the electrical energy to operate the electric motor can be provided by an arrangement of ultra-capacitors.
[0084] According to an embodiment of the present disclosure, a hybrid electric drive system of a vehicle, the hybrid electric drive system can perform the dual role of allowing drive from each powertrain to be transmitted individually to wheels of the vehicle and adding the drive from each powertrain together and seamlessly transmitting to the wheels of the vehicle. The hybrid electric drive system can comprise an electric motor and an epicyclic gear system. In case of rear wheel drive vehicles, the vehicle comprises a common propeller shaft and an internal combustion (IC) engine assembly having an IC engine gearbox such that the hybrid electric drive system is configured between the IC engine gearbox and the rear axle differential. The power from both the IC engine and the electric drive is transmitted by the common propeller shaft to the rear axle through a differential gear. In case of front wheel drive vehicles, the vehicle comprises a transaxle unit and an internal combustion (IC) engine assembly. The hybrid electric drive system can be configured between the IC engine gearbox and the differential within the transaxle unit. The Epicyclic gear system is mounted on the transaxle unit of the front wheel drive vehicle. The final drive shaft that emerges from the IC engine gearbox is modified and increased in length. By extending this final drive shaft, the sun gear of the epicyclic gear system is connected to the IC engine drive. The power from both IC engine and the electric drive is transmitted by the final drive shaft to the front axles through a differential gear.
[0085] FIG. 1A illustrates an implementation of an electric mode in a vehicle, in accordance with an embodiment of the present disclosure.
[0086] According to an embodiment, a hybrid electric drive system 106 is implemented in a vehicle 100 (also interchangeably referred to as front wheel drive hybrid electric four wheeler). The hybrid electric drive system 106 (also interchangeably referred as hybrid electric drive train) comprising an electric motor 108 and an epicyclic gear system and mode controller 110. The vehicle 100 includes a common drive shaft 236 (also interchangeably known as “output shaft differential side”), an internal combustion (IC) engine assembly 118, a gearbox 116 (also interchangeably referred to as “IC engine gear box”), front wheels of the vehicle 102, rear wheels of the vehicle 104, a battery 114, a front axle differential 238, motor controller 112, and fuel unit 120.
[0087] According to an embodiment, the vehicle 100 includes the electric motor 108, an IC engine assembly 118, a gearbox 116, the epicyclic gear system and mode controller 110, and the battery 114. The mechanism implemented in the present invention is used for converting an existing IC engine front wheel drive four wheeler in to a front wheel drive plug-in hybrid electric four wheeler as a retrofit solution. Further, the present invention is used for building a front wheel drive plug-in hybrid electric four wheeler at manufacturing stage using the prevalent IC engine vehicle architecture.
[0088] In an embodiment, the hybrid electric drive system 106 includes an epicyclic (also interchangeably known as “planetary”) gear system 110, which facilitates in utilizing the torque generated from both the electric motor 108 and the IC engine assembly 118 either independently or in a combined way. The hybrid electric drive system 106 provides seamless synchronization of the IC engine drive and the electric drive by taking it from the IC engine assembly 118, the gear box 116, and the electric motor 108. Further, the added or individual drives are transmitted to the output shaft differential side 236 of the vehicle 100 and from there on to the wheels. The technical specification of the electric drive that includes the electric motor 108 capacity, the related gear ratios of the epicyclic gear system 110 and the battery capacity can be customized as per the user’s preferences.
[0089] In an embodiment, FIG. 1A illustrates an electric mode in a vehicle. The front wheel drive hybrid electric four wheeler 100 can be operated in electric mode. The electric motor 108 provides a drive to the front axle via the epicyclic gear system 110 and the common drive shaft 236.
[0090] In an embodiment, FIG. 1B illustrates an engine mode in a vehicle 100. The front wheel drive hybrid electric four wheeler can be operated in an engine mode. The IC engine assembly 118 provides the drive to the front axle via the IC engine gearbox 116, the epicyclic gear system 110 and the common drive shaft 236.
[0091] In an embodiment, FIG. 1C illustrates a combined mode in a vehicle 100. The front wheel drive hybrid electric four wheeler can be operated in combined mode. Both the electric motor 108 and the IC engine assembly 118 provide the drive to the front axle via the epicyclic gear system 110 and the common drive shaft 236.
[0092] In an embodiment, FIG. 1D illustrates an electric reverse mode in a vehicle 100. The front wheel drive hybrid electric four wheeler can be operated in an electric reverse mode. The electric motor 108 provides a drive to the front axle via the epicyclic gear system 110 where the direction gets reversed by the epicyclic gear system 110 and then transmitted to the common drive shaft 236.
[0093] In another embodiment, the reversing of the vehicle 100 of the present invention is possible in the electric mode, thereby making the vehicle 100 versatile to use in various duty cycles. The reverse mode is possible without reversing the electric motor 108 by designing a unique usage of the epicyclic gear system in conjunction with the mode controller 110 of the hybrid electric drive system 106, thereby allowing the torque supplied by the electric motor 108 to be transferred to the final drive shaft but in opposite rotation.
[0094] In an embodiment, FIG. 1E illustrates a regeneration mode in a vehicle 100. The front wheel drive hybrid electric four wheeler can be operated in the regeneration mode. The electric motor 108 acts as a generator and charges the battery 114 while the vehicle 100 is being driven by the IC engine assembly 118. Even while braking the electric motor 108 will act as a generator and recharge the battery 114.
[0095] It is to be appreciated that while FIGs. 1A to 1E show the disclosed hybrid electric drive system 106 implemented for a front axle of the vehicle, as would be evident to those skilled in the art, the hybrid electric drive system 106 of the present disclosure can also be implemented for rear axle with suitable modifications/ changes as enumerated in the present disclosure and using knowledge available to those skilled in the art.
[0096] In another embodiment, the present invention includes an energy recuperation system that makes innovative use of mechanical power transfer from different elements of the hybrid electric drive system 106 to result in varying levels of regeneration current being fed back into the battery 114 when the vehicle 100 is decelerating or there is a need to apply brakes.
[0097] FIG. 2A illustrates a general arrangement of the vehicle from a passenger side, in accordance with an embodiment of the present disclosure.
[0098] FIG. 2A illustrates a general arrangement of the hybrid electric drive system 106 of the front wheel drive four wheeler from passenger side. The vehicle 100 includes a motor controller 112, an invertor and DC convertor 202, a battery 114, charging point 204, a Cable Harness (HV) 206, a gear lever 208, a hand brake 210, Cable Harness (LV) 212, a mode selector knob or dial 214, a mode indicator 222, a neutral safety switch 224, a Cable Harness (LV) 226, a EV Key Switch 228, an ICE Key Switch 230, an audio visual indication 232.
[0099] FIG. 2B illustrates a general arrangement of the hybrid electric drive system 106 of the front wheel drive four wheeler from driver side. The vehicle 100 includes an ICE gear box 116, an IC engine assembly 118, a break safety switch 218, a combined accelerator 220, a hand brake 210, and a gear lever 208.
[00100] FIG. 2C illustrates a general arrangement of the hybrid electric drive system 106 of the front wheel drive four wheeler from under side. The vehicle 100 includes a motor controller 112, an invertor and DC convertor 202, front axle differential 238, an IC engine assembly 118, ICE gear box 116, Battery 114.
[00101] In an embodiment, FIG 2A indicates location of the motor controller 112. A 1k ohm pre charging resistor is added across the mains contactor. Similarly, 1K ohm resistor is also added across the key switch for electric mode. Magnetically coupled accelerator 220 interacts with the mode selector knob or dial 214 to provide desired speed control. The motor controller 112 provides proportionate power as per the torque speed demand as directed by the combined accelerator 220. A thermistor control is provided internally through this motor controller 112 for the protection of the electric motor 108 winding from over-heating during rotor lock situation. The break safety switch 218 (also interchangeably referred as safety interlock switch) prevents accidental running of motor while brakes are engaged. The brake pedal is used to actuate the break safety switch 218.
[00102] In another embodiment, when the vehicle 100 is enabled to run in electric mode, the gearbox 116 connected to the IC engine assembly 118 must remain in “neutral mode”. This action has to be a fool proof system and is obtained by keeping the gear changing lever in a “neutral” position. A neutral safety switch 224 prevents activation of electric mode if the gear lever is not in the neutral position. Thus protection interlocks are achieved. Further, the motor controller 112 provides a regeneration mode to conserve the free-wheeling rotational energy of the driven wheels and also to regenerate during braking done, thereby charging the batteries. Thus this action is capable to further add extra miles as a result of regeneration. Further, the two independent electric key switches 228 and 230 are provided to isolate electric and engine mode. Speed and other display parameters are shown on custom build instrument cluster known as audio visual indication 232. The custom build cable harness 206 is provided for the power and control circuits and regeneration circuit of the motor controller 112, the combined accelerator 220, brake safety switch interlock 218, neutral gear safety switch 224, and charging circuit and vehicle operations.
[00103] In an embodiment, the hybrid electric drive system 106 is based on the fact, that the existing internal combustion engine drive train IC engine gearbox 116 is kept unaltered till IC engine assembly 118. Further, the present invention includes the hybrid electric drive system 106 which includes the electric motor 108 and the epicyclic gear system in conjunction with mode controller 110 is added between the IC engine gearbox 116 and the front axle differential final drive 238. Both the IC engine assembly 118 and electric drive power is transmitted by the common drive shaft 236 to the front axle differential 238 via a differential gear.
[00104] FIG. 3 illustrates an exemplary architecture of Electric Drive Assembly in the vehicle, in accordance with an embodiment of the present disclosure.
[00105] In an embodiment, the major parts of the hybrid electric drive system 106 includes the electric motor 108, epicyclic gear system and mode controller 110, the mode controller mechanism consisting of a mode shift axle 302, a mode shifter 304, solenoids 317 & 318, a mode controller lever 308, a mode controller lever 310, a common drive shaft 236, a EV drive assembly mounting 314, combined electro-mechanical accelerator control 220, and the motor controller (interchangeably known as controller unit) 112.
[00106] In an embodiment, the electric power is derived from the battery 114, or the hydrogen fuel cell stack mounted on the chassis frame of the vehicle 100 in the passenger or cargo compartment. Thereby, the new additions are maintained within the bodyline of the vehicle 100 and preserving the centre of gravity of the vehicle 100 as low to the ground as possible for better dynamic behaviour and balancing. The charging point 204 is located at a very convenient and easily accessible point on the vehicle 100 and charging is done by an external 15A charger. A three-phase charging adapter is also provided to aid in the fast charging of the vehicle 100.
[00107] In an embodiment, FIG 3 shows the hybrid electric drive system 106 mounted on the vehicle 100. The electric motor 108 is mounted along with the epicyclic gear system 110 in a specially fabricated housing the hybrid electric drive system 106. The hybrid electric drive system 106 is mounted on the frame of the vehicle 100 in such a way that the output shaft of the IC engine gearbox 116 and the output shaft from the hybrid electric drive assembly 106 housing are co-axial. The hybrid electric drive system 106 is mounted on the gearbox 116 of the vehicle 100 using special mountings 314. The final drive shaft 236 that emerges from the IC engine gearbox 116 is modified and increased in length. By extending this final drive shaft, the sun gear 404 of the epicyclic gear system is connected to the IC engine drive. The power from both IC engine and the electric drive can be transmitted by the final drive shaft 236 to the front wheels 102 through a differential gear 238.
[00108] FIG. 4A illustrates the epicyclic gearbox from the engine side, in accordance with an embodiment of the present disclosure.
[00109] In an embodiment, the epicyclic gear system 110 is used in the hybrid electric drive system 106. The epicyclic gear system 110 consists of a set of planet gears 402, a sun gear 404, and a ring gear 406. Further, the epicyclic gear system in conjunction with mode selector 214 includes final drive shaft differential side 236, a final drive gear 235, differential gear 238, a set of fixed gear (408, 416), a compound reverse gear 412, a reverse mode lever 308, and EV ICE mode lever 310, levers 308 and 310 attached to the mode shift axel 302 through eccentric cam bushes 423 and 424 respectively. The solenoid valves 317 and 318 operate the mode shifter 304 that has eccentric cam bushes 423 and 424 mounted on it. The movement of the mode shifter 304 is thereby transmitted to the control levers 308 and 310. The levers 308 and 310 lock and unlock the elements of the epicyclic gear system.
[00110] FIG. 4B illustrates the epicyclic gear system from the motor side, in accordance with an embodiment of the present disclosure.
[00111] In an embodiment, the epicyclic gear system 110 consists of the ring gear 406, the common drive shaft differential side 236, a pinion in-line motor side 418, a compound idler gear 420, a compound pinion gear 422, a compound reverse gear 412, and a planet carrier 426.
[00112] In an embodiment, FIGs 4A and 4B represent the epicyclic gear system 110 used in the hybrid electric drive system 106. The epicyclic gear system 110 consists of the planet gears 402, the sun gear 404, the ring gear 406, and the planet carrier 426. Unlike other epicyclic gearboxes used in automotive applications, here the output torque is taken from the sun gear 404 and the input torque is provided to the planet carrier 426 or the ring gear 406. The sun gear 404 receives the electric drive torque from the motor shaft via the planet gears 402 and the ring gear 406. Also, the sun gear 404 receives the IC engine torque from the IC engine assembly 118 and gearbox output shaft 236. This final drive shaft 236 that emerges from the IC engine gearbox 116 is modified and increased in length. By extending this final drive shaft, the sun gear 404 of the epicyclic gear system is connected to the IC engine drive. The power from both IC engine and the electric drive can be transmitted by the final drive shaft 236 to the front wheels 102 through a differential gear 238.
[00113] FIGs. 5A, 5B, and 5C illustrate the epicyclic gear system when in single mode, combined mode, electric reverse mode, respectively, and in accordance with an embodiment of the present disclosure.
[00114] In an embodiment, Fig. 5A illustrates the epicyclic gear system 110 when in single mode, where the epicyclic gear system 110 includes mode controller levers (308 and 310), ring gear 406, fixed gears (408, 416), compound reverse gear 412, compound pinion gear 422, planet carrier 426. FIG. 5B illustrates the epicyclic gear system 110 when in combined mode, where the mode controller 110 includes mode controller levers (308 and 310), the planet gears 402, the sun gear 404, the ring gear 406, the fixed gear (408, 416), the compound pinion gear 422, the planet carrier 426, the compound reverse gear 412, the compound idler 420, the drive shaft differential side 236. FIG. 5C illustrates the epicyclic gear system 110 when in electric reverse mode, where the mode controller 110 includes mode controller levers (308 and 310), the planet gear 402, the sun gear 404, the ring gear 406, the fixed gears (408, 416), the compound reverse gear 412, the compound pinion gear 422, the planet carrier 426, the drive shaft differential side 236, and the compound idler gear 420.
[00115] In another exemplary embodiment, FIGs 5A, 5B and 5C illustrates uniquely designed epicyclic gear system 110 consists of a cam and solenoid operated system, which controls the operation of various modes by locking different elements of the planetary gearbox. There are two levers (308, 310) that can be moved by the cam and solenoid mechanism in different positions to enable the three different modes they are electric or IC engine mode, combined mode, and reverse in electric mode. The locking and unlocking of the planetary gearbox elements are done via the three pinion gears 408, 412, and 416. As shown in FIG 5A for electric or IC engine mode, the levers (308, 310) are moved in such a position that the planet carrier 426 is not locked and can receive the power from the electric motor 108. The ring gear 406 is locked in position by the pinion 408. Further, depending on the switch 228 and 230 being in electric mode or engine mode either of the modes is enabled. For electric mode, the torque from the electric motor 108 is transmitted to the unlocked planet carrier 426 through the pinion gears 418, 420, and 422. This torque is then transmitted to the sun gear 404 to further transmit it to the drive shaft 236. For engine mode, the torque from the engine is transmitted to the sun gear 404 directly by the gearbox output shaft 236. For combined mode, the levers 308, 310 are moved in a position to enable both the planet carrier 426 and the ring gear 406 to stay unlocked. The torque from the electric motor 108 is transmitted to the planet carrier 426 and then to the sun gear 404. Additionally, the sun gear 404 also receives the IC engine torque from the gearbox output shaft 236. The unlocked ring gear 406 allows the sun gear 404 to adjust to the torque being transmitted by both the electric motor 108 and the IC engine assembly 118 at the same time. Now, to reverse the vehicle 100 in electric mode, the levers 308, 310 are positioned as shown in FIG 5C. Such positioning of the levers 308, 310 causes the planet carrier 426 to be locked by the pinion 416 and the ring gear 406 to mesh with the compound pinion gear 412. The electric motor torque is now transmitted to the ring gear 406. In this position as the planet carrier 426 is locked by the fixed gear 416 the planet gears 402 are locked and cannot revolve around the central gearbox axis but can only rotate around their own axis. This causes the sun gear 404 to rotate in a direction that is opposite to the rotation of the ring gear 406 and hence causing the drive shaft 236 to rotate in the opposite direction and give the reverse direction to the wheels 102, 104.
[00116] In another embodiment, alternatively the mode controller 214 of the epicyclic gear system 110 can be operated electronically using a microcontroller based programmable logic. Here the movement of the two levers 308, 310 can be controlled electronically by the programmable logic that would operate the cam and solenoid mechanism to enable the three different modes Electric or IC engine mode, combined mode, and reverse in electric mode.
[00117] In an embodiment, the programmable logic can be programmed to enable different modes based on operating conditions, such as speed of the vehicle, acceleration/deceleration of the vehicle, battery condition, state of charge of the battery, and other such parameters.
[00118] FIG. 6 illustrates the combined electro-mechanical accelerator of the vehicle, in accordance with an embodiment of the present disclosure.
[00119] In an embodiment, a specifically designed electro-mechanical accelerator is represented in FIG.6. The electro-mechanical accelerator includes combined accelerator 220, accelerator pedal 604, mechanical cable 606, mechanical cable 608, mechanical adjuster 610, magnetic coupling and sensor 612, accelerator support 614, cable stretcher 616, and accelerator support 618.
[00120] In another embodiment, the combined accelerator 220 performs the function of accelerator for both electric and engine drives, which provides ease of operation to the driver for maintaining their driving habits. The accelerator pedal 604 operates both electric and internal combustion engine accelerators in unison. The mechanical cable 608 operates the mechanical system that provides the accelerator function for the internal combustion engine 118. The magnetic coupling and sensor 612 pass on the signal to the motor controller 112, which provides the accelerator function for the electric motor drive. Thus, the hybrid operation can be easily achieved through the common accelerator. There is a designed phase lag that allows the IC engine to lag behind the electric motor 108 when the user operates the accelerator pedal 604 while driving in combined mode.
[00121] In another exemplary embodiment, the hybrid electric drive system 106 of the present invention performs the role of synchronizing and transferring the torque generated by the two power-trains to the wheels of the vehicle 100. The hybrid electric drive system 106 performs the dual role of allowing drive from each powertrain to be transmitted individually to the wheels of the vehicle 102, 104 as demanded by the user, and adding the drive from each powertrain together and seamlessly transmitting to the wheels of the vehicle 102, 104 as demanded by the user. The hybrid electric drive system 106 allows true addition of the capabilities of the two different power-trains. The hybrid electric drive system 106 does not split the torque generated by either of the power-trains but adds the torque to satisfy the vehicle load demand by synchronizing the drives to best utilize the torque-speed characteristics of the two power-trains together. The hybrid electric drive system 106 makes a unique use of the epicyclic gear system in combination with the mode controller 110 to provide the necessary synchronization of the drives from the two distinct power-trains. When the user operates the hybrid electric drive system 106 for the combined mode, the epicyclic gear system is uniquely operated by the mode controller 110 to obtain the benefit of the torque-speed characteristics of the individual power-trains. The combined accelerator conveys the user demand to the hybrid electric drive system 106 and based on the total torque demand of the vehicle 100 the combination of the two power-trains is managed to deliver the required torque at the best possible efficiency. The combined accelerator 220 has a designed phase lag that allows the IC engine assembly 118 to lag behind the electric motor 108 and thus take advantage of the high initial starting torque of the electric power-train.
[00122] FIG. 7A illustrates a graphical representation of the vehicle with resultant torque-speed characteristics, in accordance with an embodiment of the present disclosure.
[00123] In an embodiment, FIG. 7A represents the resultant representational torque speed characteristics delivered by the hybrid electric drive system 106. It can be seen that the resultant torque of the hybrid electric drive system 106 eclipses the maximum torque possible of the IC engine assembly 118 and this high resultant torque is available even at very low initial starting speed, thereby reducing the load on the IC engine assembly 118 significantly.
[00124] In an embodiment, FIG. 7A represents a graph, where x-axis is speed in revolutions per minute (rev/min) and y-axis is torque in N-m (newton-metre). The graph represents a torque speed characteristics of electric vehicle (EV) motor and a torque speed characteristics of an internal combustion engine (ICE). Further, the graph represents the resultant combined torque speed characteristics of ICE and EV motor.
[00125] FIG. 7B illustrates graphical representation of the vehicle with resultant torque-speed characteristics under various drive cycles, in accordance with an embodiment of the present disclosure.
[00126] In an embodiment, FIG. 7B represents a graph, the resultant representational torque speed characteristics delivered by the hybrid electric drive system 106 under various drive cycles like a start-up and heavy acceleration (power zone), partial load condition (eco zone), and a steady state cruise condition (cruise zone). It can be seen that the majority of the high torque from the resultant hybrid drive becomes available even from low initial speeds. This helps in keeping the engine speeds much lower than desired as the engine isn’t required to provide the complete torque needed to meet the load. By synchronizing the drives, the hybrid electric drive system 106 can reduce the load on the IC engine and thereby reduce the fossil fuel consumption and carbon and other harmful emissions by nearly up to 50%. Further reduction in harmful emissions can be achieved by improving the efficiency of the electric motor and battery pack.
[00127] In an embodiment, FIG. 7B represents a graph, where x-axis is speed in revolutions per minute (rev/min) and y-axis is torque in N-m (newton-metre). The graph includes representation of different gears such as 1st gear, 2nd gear, 3rd gear, etc. of the IC engine gearbox along with various zones such as cruise zone, eco zone and power zone. It can be seen that the resultant torque-speed characteristics of the hybrid electric system allows the vehicle to be operated in 3rd or higher gears in the power zone unlike when in the IC engine mode where 1st or 2nd gear is needed in power zone. This translates to the engine being loaded less to provide the necessary drive, when the vehicle is driven in the combined mode, thereby resulting is savings of fuel and reduction in harmful emissions from the IC engine.
[00128] FIG. 7C illustrates a graphical representation of the vehicle with resultant reduction in IC engine usage, in accordance with an embodiment of the present disclosure.
[00129] In an embodiment, FIG. 7C represents the graph indicating a reduction in usage of IC engine power and in turn reduction in usage of fossil fuel and reduction in tail-pipe emissions by utilizing the uniquely designed Hybrid Drive System.
[00130] In an embodiment, FIG. 7C represents a graph which represents the saving in ICE Power in percentage (in %age) due to Hybrid Electric Drive System. When the vehicle 100 is operated at the 1st gear the maximum ICE power saving may be 73.68% and the minimum ICE power savings may be 68.42%. When the vehicle 100 is operated at the 2st gear the maximum ICE power saving may be 62.11% and the minimum ICE power savings may be 53.19%. When the vehicle 100 is operated at the 3rd gear the maximum ICE power saving may be 45.05% and the minimum ICE power savings may be 30.95%. The maximum ICE power saving in power zone may be 67.90% and the minimum ICE power saving in power zone may be 60.81%. The maximum ICE power saving in eco zone may be 53.58% and the minimum ICE power saving in eco zone may be 42.07%. The maximum ICE power saving in cruise zone may be 40.87% and the minimum ICE power saving in cruise zone may be 30.99%. Finally, the overall maximum ICE power saving may be 54.11% and the overall minimum ICE power saving may be 44.11%.
[00131] Although this present invention has been described herein with respect to a number of specific illustrative embodiments, the foregoing description is intended to illustrate, rather than to limit the invention. Those skilled in the art will realize that many modifications of the illustrative embodiment could be made which would be operable. All such modifications, which are within the scope of the claims, are intended to be within the scope and of the present invention.

ADVANTAGES OF THE PRESENT DISCLOSURE
[00132] The present disclosure provides an efficient mechanism to build low emissions, fuel-saving hybrid electric drive system that can operate independently and in combined assist mode. Such a system would improve the fuel economy significantly and this would also mean a significant reduction in CO2 emissions per litre of fuel consumed.
[00133] The present disclosure provides a hybrid electric drive system that increases the life expectancy of the vehicle.
[00134] The present disclosure provides a hybrid electric drive system that provides a cost-effective solution to reduce the emissions from vehicles.
[00135] The present disclosure provides a hybrid electric drive system that helps in conserving the usage of fossil fuel thereby helping in reducing the import bills of such fuels for the nation.
[00136] The present disclosure provides a hybrid electric drive system which helps to extend the use of existing IC engine driven vehicle architectures and hence reduce the design and manufacturing costs for manufacturers.
, Claims:1. A hybrid electric drive system (106), said hybrid electric drive system (106) for a vehicle (100), comprising:
an electric motor (108); and
an epicyclic gear system (110);
wherein the hybrid electric drive system (106) is configured between an Internal Combustion engine (118) of the vehicle (100) and a differential (238) of an axle of the vehicle (100);
wherein the hybrid electric drive system (106) performs a dual role of allowing drive from any or both of the IC engine (118) and the electric motor (108) to be transmitted, individually or adding the drive from the two, seamlessly to wheels (102, 104) of the corresponding axle of the vehicle (100), thereby enabling driving the vehicle (100) in three different driving modes, the three driving modes comprising an electric driving mode, an IC engine driving mode, and a combined driving mode;
wherein the hybrid electric drive system (106) comprises a pair of levers (308 and 310) that move to different positions to enable different driving modes; and
wherein the hybrid electric drive system (106) comprises a cam and solenoid based control mechanism to move the pair of levers (308 and 310) to different positions, based on signals to enable different driving modes.
2. The hybrid electric drive system (106) as claimed in claim 1, wherein the cam and solenoid based control mechanism comprises;
a mode shifter (304) mounted on a mode shift axle (302),
a pair of eccentric cam bushes (423 and 424) mounted on the mode shift axle (302);
a pair of solenoids (317 and 318) coupled to the mode shifter (304) to operate the mode shifter (304);
wherein the pair of levers (308 and 310) is mounted on the eccentric cam bushes (423 and 424) such that when the solenoids are actuated, the resultant rotation of the mode shift axle (302) causes the levers (308 and 310) to move to different positions to enable different driving modes.
3. The hybrid electric drive system (106) as claimed in claim 2, wherein the control mechanism comprises a programmable logic operatively coupled to the pair of solenoids (317 and 318) to provide the signals to actuate the pair of solenoids (317 and 318), thereby enabling change of the driving modes from a driver’s seat of the vehicle (100).
4. The hybrid electric drive system (106) as claimed in claim 1, wherein the axle connected to the hybrid electric drive system (106) is any of a front axle or a rear axle of the vehicle (100) and wherein the hybrid electric drive system (106) is coupled to the rear axle through a propeller shaft (236) for a rear wheel drive vehicle, and wherein the hybrid electric drive system (106) is located within a transaxle unit of the vehicle and directly coupled through the final drive shaft (236) to a differential of the transaxle for a front wheel drive vehicle.
5. The hybrid electric drive system (106) as claimed in claim 4, wherein the epicyclic gear system (110) allows output to be taken from a sun gear (404) and input to be given to at least one planet carrier (426) or a ring gear (406);
power from both the IC engine assembly (118) and the hybrid electric drive system (106) is transmitted to the corresponding axle;
the power from both the IC engine assembly (118) and the electric motor (108) is transmitted to the sun gear (404) such that the sun gear (404) transmits the power to the corresponding axle;
the hybrid electric drive system (106) comprises a first pinion gear (416) that locks and unlocks planet carrier (426), and a third pinion gear (408) that locks and unlocks the ring gear (406); and
the first and third pinion gears are mounted on levers (308) and (310) that move in different positions to enable locking or unlocking of at least one of the planet carrier (426) and the ring gear (406) for enabling different driving modes.
6. The hybrid electric drive system (106) as claimed in claim 5, wherein the hybrid electric drive system (106) comprises a second pinion gear (412) that transmits power from the electric motor (108) to the ring gear (406).
7. The hybrid electric drive system (106) as claimed in claim 5, wherein for electric or IC engine mode, the levers (308) and (310) are moved to a position such that the planet carrier (426) is unlocked, the electric motor (108) power is transmitted to the planet carrier (426) through a series of pinion gears (418), (420), and (422), and the ring gear (406) is locked by pinion (408) such that the hybrid electric drive system (106) in the electric mode or IC engine mode respectively is enabled.
8. The hybrid electric drive system (106) as claimed in claim 5, wherein in the combined mode, the levers (308 and 310) are moved to a position such that the planet carrier (426) is unlocked, the motor power is transmitted to the planet carrier (426), and the ring gear (406) is unlocked, and wherein unlocking of the ring gear (406) allows the sun gear (404) to adjust to the power being transmitted from both the IC engine and the electric motor (108).
9. The hybrid electric drive system (106) as claimed in claim 8, wherein a combined accelerator (220) designed with a configurable phase lag allows the electric motor (108) to speed up earlier than the IC engine owing to high initial starting torque of the electric power-train while being driven in the combined mode.
10. The hybrid electric drive system (106) as claimed in claim 5, wherein, for reverse in electric mode, the levers (308) and (310) are moved in a position so that the planet carrier (426) is locked by pinion (416), and electric motor power (108) is transmitted to the ring gear (406) via compound pinion gear (412) causing the sun gear (404) to spin in opposite direction to that of the ring gear (406), thereby reversing the rotation.
11. The hybrid electric drive system (106) as claimed in claim 10, wherein locking of the planet carrier (426) and providing electric motor (108) power to the ring gear (406) causes the sun gear (404) to provide the output torque to the drive shaft (236) to spin in a direction opposite to the motor rotation.
12. The hybrid electric drive system (106) as claimed in claim 5, wherein during regeneration, mechanical power is transferred from the sun gear (404) to the planet carrier (426) with the ring gear (406) being locked or unlocked results in different levels of regeneration to allow a battery pack (114) to be recharged depending on the state of charge.
13. The hybrid electric drive system (106) as claimed in claim 1, wherein the vehicle (100) comprises a fuelling system having a hydrogen fuel cells stack for providing electrical energy to operate the electric motor (108), wherein the hydrogen fuel cells stack, a liquid hydrogen tank and a battery pack are mounted on chassis of the vehicle (100) under its body.
14. The hybrid electric drive system (106) as claimed in claim 1, wherein electrical energy to operate the electric motor (108) is provided by an arrangement of ultra-capacitors.
15. A vehicle (100) comprising the hybrid electric drive system (106) as claimed in claim 1.