Claims:1. A powertrain assembly (PA) in an alternative powertrain vehicle, said powertrain assembly (PA) comprising of:
a prime mover (101), said prime mover (101) is supported on a primary housing (201), said primary housing (201) enclosing a transmission system (TS), said transmission system (TS) having a transmission axis (T-T’) passing longitudinally through the axis of rotation of a drive shaft assembly (DSA) and a driven shaft assembly (DRSA), said drive shaft assembly (DSA) operatively connected to the driven shaft assembly (DRSA) through a transmission means (206);
a cover member (202), said cover member (202) is detachably attached to the primary housing (201);
a secondary housing (203), said secondary housing is detachably attached to a primary housing (201); and
a pressure and oil control system, said pressure and oil control system includes
an oil separator device (105) operatively connected to the transmission system (TS),
an oil separator structure (401), and
a plurality of control passages (302a, 302b).
2. The powertrain assembly (PA) for an alternative fuel as claimed in claim 1, wherein said oil separator device (105) is mounted on the primary housing (201) at least partially above the transmission axis (T-T’) and operatively connected to the oil separator structure through a breather tube (106).
3. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 1, wherein said oil separator device (105) comprising of
an oil separator case (501) configured to have a filter member (506), an oil separator cover (502) wherein said oil separator cover (502) is detachably attached to an oil separator case (501) through plurality of fasteners (503).
4. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 3, wherein said filter member (506) composed of material known in the art like foam type or paper type.
5. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 3, wherein said filter member (506) separate oil from the fumes and said separated oil is collected in a drain collector (504) through a drain collection hole (509).
6. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 3, wherein said oil separator case (501) is configured with a vent hole (507) to vent out separated air into the atmosphere after passing through the filter member (506).

7. A powertrain assembly (PA) in an alternative powertrain vehicle, said powertrain assembly (PA) comprising of:
a prime mover (101), said prime mover (101) is supported on a primary housing (201), said primary housing (201) enclosing a transmission system (TS), said transmission system (TS) having a transmission axis (T-T’) passing longitudinally through the axis of rotation of a drive shaft assembly (DSA) and a driven shaft assembly (DRSA), said drive shaft assembly (DSA) operatively connected to the driven shaft assembly (DRSA) through a transmission means (206),
a cover member (202), said cover member (202) is detachably attached to the primary housing (201),
a secondary housing (203), said secondary housing is detachably attached to a primary housing (201), and
a pressure and oil control system, said pressure and oil control system includes
an oil separator structure (401), said oil separator structure (401) configured to have a filter member (601) at a predetermined location, and
a plurality of control passages (302a, 302b).
8. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 1 or claim 7, wherein said oil separator structure (401) is configured to have a predetermined profile formed by both the halves of the primary housing (201) and the cover member (202).
9. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 8, wherein said predetermined profile includes a maze type profile.
10. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 8, wherein oil separator structure (401) is formed near electric motor (101) at least partially above the transmission axis (T-T’).
11. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 7, wherein said oil separator structure (401) configured to have breather pipe (602) to vent out separated air from the fumes.
12. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 1 or claim 7, wherein said plurality of control passages (302a, 302b) includes a pressure control passage (302a), and an oil control passages (302b).
13. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 12, said pressure control passage (302a) is formed at least partially above the transmission axis (T-T’) on the upper most region of the powertrain assembly (PA).
14. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 12, wherein said oil control passages (302b) are provided in the rear most region of the powertrain assembly (PA) at least partially below the transmission axis (T-T’).

15. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 1 or claim 7, wherein said powertrain assembly (PA) is pivotally connected to the frame assembly (FA) of an electric vehicle.

16. The powertrain assembly (PA) for an alternative powertrain vehicle as claimed in claim 1 or claim 7, wherein said cover member (202) is configured to have oil pouring port (107a) and oil drain port (107b).
, Description:[0001] The present subject matter relates to the powertrain assembly. More particularly, the present subject matter relates to pressure and oil control system for a powertrain assembly.
BACKGROUND
[0002] Over the past few years, the investment and market viability of the electrical vehicle are growing in a wide range because of high costs of fossil based fuel and at the same time pressing need to be environment-friendly leading to alternative means of transportation. The alternative means includes electric vehicles, where these vehicles use motor as the prime mover. The electric vehicle is attractive in that the power unit in the form of a rechargeable battery pack is environmentally clean as it does not pollute the air during its operation and its operation is silent. Hence preference of most users is rapidly shifting towards electrical vehicle for their regular usage. But electric drives must withstand predetermined temperature ranges as well as shock, vibration.

BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.
[0004] Fig. 1 illustrates a left side view of the powertrain assembly (PA), as per preferred embodiment of the present invention.
[0005] Fig. 2 illustrates a top cut section view across transmission axis (T-T’) of the powertrain assembly as shown in figure 1 as per preferred embodiment of the present subject matter.
[0006] Fig. 3 illustrates a rear cut section view of the powertrain assembly across M-M’ axis as shown in figure 1, as per preferred embodiment of the present invention where few parts are omitted.
[0007] Fig. 4a illustrates a partial perspective view of the powertrain assembly where few parts are omitted from the figure as per preferred embodiment of the present subject matter.
[0008] Fig. 4b illustrates a cut section view of the oil separator structure across R-R’ axis of the powertrain assembly as shown in figure 1 where few parts are omitted from the figure as per preferred embodiment of the present subject matter.
[0009] Fig. 5a illustrates an exploded view of oil separator device as per preferred embodiment of the present subject matter.
[00010] Fig. 5b illustrates a perspective view of oil separator device of the powertrain assembly, where few parts are omitted from the figure as per preferred embodiment of the present subject matter.
[00011] Fig. 6 illustrates a cut section view of the oil separator structure across J-J’ axis of the powertrain assembly as per alternative embodiment where few parts are omitted from the figure as per preferred embodiment of the present subject matter.

DETAILED DESCRIPTION
[00012] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder. It is contemplated that the concepts of the present invention may be applied to any type of vehicle employing the similar powertrain within the spirit and scope of this invention.

[00013] Further "front" and "rear", and "left" and "right" referred to in the ensuing description of the illustrated embodiment refer to front and rear, and left and right directions as seen from a rear portion of the powertrain assembly and looking forward. Furthermore, a longitudinal axis (Y-Y’) unless otherwise mentioned, refers to a front to rear axis relative to the powertrain assembly, while a lateral axis (L-L’) unless otherwise mentioned, refers generally to a side to side, or left to right axis relative to the powertrain assembly. The detailed explanation of the constitution of parts other than the present subject matter which constitutes an essential part has been omitted at suitable places.

[00014] The detailed explanation of the constitution of parts other than the present subject matter which constitutes an essential part has been omitted at suitable places. The word “prime mover” and “electric motor” used interchangeably throughout the specification.

[00015] Typically, the high costs of fossil based fuel lead to alternative means of transportation. In addition to that, original equipment manufacturer (OEMs) and customers are being driven down a path to reduce vehicular emissions by electrifying the drivetrain which they have the capability to propel vehicles while leaving space inside the vehicles to allow packaging of large battery packs enabling adequate driving range in single charge. As in automobiles torque and speed are important parameters, these can vary as per different segment of the vehicle; therefore, primarily electric vehicles are designed by keeping these two parameters in mind.

[00016] It is always a challenge for the automobile manufactures to have appropriate balance between both torque and speed, so in order to achieve different speed at varying loads similarly different torque at different loads requires optimal transmission system / ratios. Power generated from the electric motor when transmitted directly to drive wheel will lead to inappropriate torque since direct drive results in uncontrolled speed or sub-optimal speed and undesirable operating conditions to achieve best performance i.e. torque and rpm (revolutions per minute). However, in-wheel hub motor is one of the promising technologies in automotive electrification.

[00017] Typically, in-wheel hub motor drive type configuration are relatively is a rapidly developing solution along with variable speed drive market but at the same time the inherent disadvantage of in-wheel motors is limited torque delivery to drive wheel independently. Thus, in order to get desired or higher torque, the size of in-wheel motor should be increased. This increased size of in-wheel hub motor leads to increase in the size of the wheel assembly. So, there is trade off by moving the drivetrain mass from the sprung to the unsprung mass as well as space availability. This increased unsprung mass is often challenged with increased unsprung mass/sprung mass ratio which can result in dangerous, uncomfortable vehicles. Increasing wheel size brings in additional drawbacks in terms of packaging, inertia losses, seating height etc. Typically, in vehicles like two wheelers (like scooters) or three wheelers the wheel assembly size is smaller and thus, increased wheel assembly size or addition of components cause leads to s layout constraints in designing a compact low weight power train. Further, the wheel rim may bend due to high inertia of electric motor and which can also causes the water to get inside the electric motor easily. This ingression of water inside motor may cause the electric motor short circuit. Moreover, it is difficult to provide electric motor cooling as it is disposed inside wheel hub, which tends to further decrease the efficiency of the electric motor because of heat and there by decrease the electric vehicle range, as more power or energy can get wastage e in heat energy from the battery or energy source.

[00018] Therefore, for best vehicle performance and optimal operating conditions, to transmit power from the power unit to drive wheel of the vehicle a transmission system or gear box is typically provided. However, a trade-off between torque requirement and range of the vehicle is difficult since at higher torque requirements the range of the vehicle drops. Thus, to assure an effective torque developed by drive wheel and the force applied to road surface a special attention has been given to the electric drive comprising of independent electric motor mounted on the frame assembly.

[00019] Typically, independent electric motor is connected to the drive wheel through the endless transmission. Although high capacity of the electric motor adapted but albeit at trade-off of increase in weight and cost. Further, higher capacity electric motors draw more power from the batteries which is undesirable in terms of durability, reliability, range of travel, efficiency as well as cost of ownership.

[00020] Thus, to increase the range of the electric vehicle, high watt-hour batteries need to be implemented within the electric vehicle. the high capacity motor and high watt-hour batteries adversely affects the vehicle layout in terms of aspects like adequate foot space or luggage space or utility space, frame design and also involves custom design of frame assembly to support the high capacity electric motor and high watt-hour batteries as well as its location/mountings. Further, the electric motor has inherent disadvantage of overheating generally because of incorrect voltage where if voltage is less the electric motor use to draw more current from the batteries or if voltage is more than increased voltage causes electric motor to run faster.

[00021] In addition to this, footprints of roads have been widespread to areas which were previously inaccessible, especially hilly areas where grade, pitch, ambient temperature and slope are important components hence steep gradients, elevation, ambient temperature is a major reason for malfunctioning of electric motor besides capability of vehicle to take gradients even on full loads. Hence, lubrication is required to reduce the frictional losses and heat wherein most common form of lubrication involves immersing of transmission parts in oil which is then splashed by rotation throughout the casing over the parts. But especially when a vehicle travels at a high speed on an expressway, the rotational elements in the powertrain assembly rotate at high speed. This intensifies the churning of the lubrication oil which results in increase of heat energy within transmission system. Also, at high speed, the electric motor dissipates more heat which further increases the heat energy within the transmission system. This heat increases the pressure inside the transmission system. This, increases the probability of the lubrication oil leaking to the outside of the casing as oil seal may pop out because of high pressure which can potentially make the electric motor and other transmission parts including chain drive and gear drive system to run in dry state and lead to cascading wear in transmission components. Thus, result in rough performance of the powertrain assembly accompanied by noise and vibration resembling a rattle which increases with speed of the vehicle. Further, it causes rapid wear and tear of the chain links which in turn results in slackness of the chain drive; causing adverse loss in the efficiency of the transmission and electric motor performance as well as undesirable durability.

[00022] Furthermore, the oil is heated to such an extent that an oil cooler which is typically used to avoid overheating of electric motor and transmission components becomes either defunct, inadequate or economically disadvantageous to provide separate oil cooler of large capacity. Enhancing capacity of oil cooler leads to increased number of parts, cost and major layout changes from a conventional design & thus undesirable. The major layout changes include mounting and availability of efficient oil cooler.

[00023] In light of increasing fossil based fuel prices there is need to develop the powertrain assembly that can help to address above issues and which is affordable and within the means of the masses. Thus, there exists as need to design an improved powertrain assembly which overcomes all the cited problems & other problems in known art. As per the present invention, a powertrain assembly for a vehicle is proposed which alleviates one or more drawbacks highlighted above.

[00024] It is object of the present invention to provide a powertrain assembly configured to have efficient lubrication and breathing system without use of an additional oil cooler.

[00025] It is another object of the invention is to provide powertrain assembly ensuring improved cooling for prime mover which will increase the range of the alternative powertrain vehicle.

[00026] It is yet another object of the invention to provide a powertrain assembly which avoids fumes emission into atmosphere.

[00027] It is an object of the invention to provide a powertrain assembly which ensures ease of serviceability and assembly.

[00028] The present subject matter relates to the powertrain assembly for an alternative powertrain vehicle. The powertrain assembly configured to have pressure and oil control system. The pressure and oil control system comprises an oil separator device operatively connected to the transmission system, an oil separator structure, and a plurality of pressure control passage. The plurality of control passages communicates between the primary housing and secondary housing. The plurality of control passages includes a pressure control passage and an oil control passages.

[00029] The oil control passages are provided in the rear most region of the powertrain assembly below the transmission axis. Further, the pressure control passage is formed at least partially above the transmission axis on the upper most region of the powertrain assembly. The predetermined position of the oil control passages ensures optimum level of lubricating oil in the transmission system. Furthermore, the predetermined position of the pressure control passage ensures that fumes generated inside the secondary housing should communicate with the primary housing and travel to the oil operator structure.

[00030] The oil separator structure configured to have maze type profile which resist the flow of the fumes and maintain the optimum pressure and temperature within the transmission system. Furthermore, the oil separator structure is operatively connected to the oil separator device. The operator device separates the oil from the fumes and allows the air to escape in the atmosphere and traps the oil in the drain collector. As per alternative embodiment, the filter member is provided in the oil separator structure.

[00031] Further, a single oil pouring port is provided in the powertrain assembly to pour the oil during servicing. Further, a single oil drain port is provided in the powertrain assembly to drain the oil while servicing.

[00032] Furthermore, the details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.

[00033] Figure 1 illustrates the side view of powertrain assembly (PA) as per preferred embodiment of the present invention. For example, and by no way limiting the scope of the subject matter. The present invention has a frame assembly (FA) similar to a two wheeler or small commercial passenger vehicles frame known in the art. The powertrain assembly (PA) is pivotally connected to the frame assembly (FA) of the alternative powertrain vehicle. The alternative powertrain vehicle includes electric vehicle. The present invention can have steering system (not shown) and a seat assembly (not shown). The powertrain assembly (PA) includes a prime mover (101), as per preferred embodiment i.e. electric motor (101) is operatively connected to the drive wheel (100). A braking system (103) is attached to drive wheel (100). In alternative embodiment brake system (103) can be inbuilt in drive wheel (100). A centre stand (102), used especially when the operator is not on the vehicle. The centre stand (102) is operatively connected to at least portion of the powertrain assembly (PA). A cushioning means (not shown) is used to dampen the road shocks, wherein said cushioning means (not shown) one end is connected to the cushion member mount structure (104). An oil separator device (105) is mounted on the primary housing (as shown in figure 2) which is operatively connected to the transmission system (TS) using breather tube (106). A single oil pouring port (107a) is provided in the powertrain assembly (PA) to pour the oil during servicing. Further, a single oil drain port (107b) is provided in the powertrain assembly (PA) to drain the oil while servicing.

[00034] Figure 2 illustrates a sectional top view of a powertrain assembly (PA) across transmission axis (T-T’) as per preferred embodiment of the present subject matter. For example, and by no way limiting the scope of the subject matter, a prime mover (101) is supported on a primary housing (201). The primary housing (201) enclosing a transmission system (TS). In present embodiment, the transmission system (TS) includes a drive shaft assembly (DSA) operatively connected to the driven shaft assembly (DRSA) through transmission means (206), and a cover member (202). The cover member (202) is detachably attached to the primary housing (201). The oil pouring port (107a) (as shown in figure 1) and oil drain port (107b) (as shown in figure 1) are formed in the cover member (202). Furthermore, a wheel assembly (212) is removably attached to a secondary housing (203) such that secondary housing (203) sandwiched between the wheel assembly (212) and primary housing (201) when viewed from the rear of the powertrain assembly (PA). The secondary housing (203) encloses a gear reduction system. The drive shaft assembly (DSA) includes driving sprocket (204), said driving sprocket (204) is installed on a drive shaft (207). The drive shaft (207) includes shaft of the prime mover (101) i.e. electric motor (101). A driven shaft (208) is adapted to have external splines at one of its end to accommodate the driven shaft assembly (DRSA). Further, a driven shaft assembly (DRSA) includes a driven sprocket (205) and a drive train oscillation reduction device (213) both are installed on a driven shaft (208). As per preferred embodiment, transmission means (206) includes a chain. The power from the electric motor (101) drives the driving sprocket (204) of the drive shaft assembly (DSA). The driving sprocket (204) drives the driven sprocket (205) through transmission means (206). Typically, the driven shaft (208) further operatively connected to a wheel shaft (209) through gear reduction system. The gear reduction system includes at least one driving gear (214) installed on the driven shaft (208) and at least one driven gear (215) installed on the wheel shaft (209). The wheel shaft (209) is parallel and alongside the driven shaft (208) such that driving gear (214) is engaged with the driven gear (215). The driven shaft (208) has both the ends are rotatably supported on the bearings (210) such that one end is rotatably supported on the secondary housing (203) and another end is rotatably supported on the primary housing (201). Further, for the wheel shaft (209) both the ends are rotatably supported on the bearings (211) such that one end is rotatably supported on the secondary housing (203) and another end is rotatably supported on the primary housing (201).Thus, drive shaft assembly (DSA) rotates the driven shaft assembly (DRSA) which further drives the wheel assembly (209).

[00035] Figure 3 illustrates the rear side section view of the powertrain assembly across R-R axis as shown in figure 1. The primary housing (201) is detachably attached to the secondary housing (203) using plurality of fasteners (301). Further, the cover member (202) is detachably attached to the primary housing (201) such that cover member (202) and primary housing (203) forming a transmission housing which encloses the transmission system (TS). The powertrain assembly (PA) is configured to have pressure and oil control system comprising of an oil separator structure (401) (as shown in fig. 4), oil separator device (105) (as shown in fig. 1) and plurality of control passages (302a, 302b). The plurality of control passages (302a, 302b) includes at least one pressure control passage (302a) and at least three oil control passages (302b). The primary housing (201) and the secondary housing (203) together form a pressure control passage (302a) and oil control passages (302b). The pressure control passage (302a) and the oil control passages (302b) are formed in the predetermined position, specifically in proximity of driven shaft assembly (DRSA) such that the oil control passages (302b) is formed at least partially below transmission axis (T-T’) and communicates between primary housing (201) and secondary housing (203) to transfer fluid during normal driving operations. Furthermore, the pressure control passage (302a) is at least partially above the transmission axis (T-T’) such that it communicates between the primary housing (201) and secondary housing (203) to allow the fumes to travel in between primary housing (201) and secondary housing (203) and finally from secondary housing (203) towards the primary housing (201) as shown by fume lines in illustration. Thus, the pressure control passage (302a) and oil control passages (302b) maintain the optimum pressure within the powertrain assembly (PA).

[00036] Figure 4a illustrates partial perspective view of the powertrain assembly (PA) depicting fumes flow from the primary housing (201) towards oil separator structure (401) and cooling of electric motor (101) where few parts are omitted from the figure. The housing (402) of the motor (101) is configured to have cooling and guide fins (403). The natural air passes through the cooling and guide fins (403) which ensures effective cooling of the motor (101). The air directed towards the electric motor (101) is guided through the cooling and guide fins (403). Thus, natural air is in convective contact with electric motor (101) for longer duration due to cooling and guide fins (403) on the electric motor (101). As shown below in equation, that the amount of heat transfer Q through convection directly depends on time for heat transfer.
Equation - Q/t= h*A*?T
Where:
Q/t = rate of heat transfer (J/s)
h = Convective heat transfer coefficient (Watt/(m2K)
A = surface area of heat transfer (m2)
?T = temperature difference(K)
[00037] Further the electric motor (101) is cooled by the lubricating oil in the primary housing (201) as electric motor (101) and primary housing (201) both are in direct contact with each other thus heat is transferred from the electric motor (101) through conduction and then to the lubricating oil through convection. Thus, above construction leads to efficient cooling of the electric motor (101) by increasing the transfer of heat through conduction and convection. Moreover, the fumes travel from pressure control passage (302a) towards oil separator control structure (401) (as shown in fig. 4b) and finally towards the oil separator device (105) (as shown in fig. 1) through breather tube (106) as per preferred embodiment.

[00038] Figure 4b illustrates the cut section view of the powertrain assembly (PA) across R-R axis as shown in figure 1 depicting flow of fumes within oil separator structure (401). The oil fumes from the pressure control passage (302a) passes through oil separator structure (401). The oil separator structure (401) is formed near electric motor (101) at least partially above the transmission axis (T-T’). The oil separator structure (401) is configured to have a maze type profile formed by both the halves i.e. primary housing (201) and cover member (202). Further, the oil separator structure (401) is operatively connected to the oil separator device (105) (as shown in fig 1) through a breather tube (106) (as shown in fig. 1). Thus, fumes formed in the primary housing (201) and secondary housing (203) exit from the oil separator structure (401) so that oil droplets in the fumes are intercepted by the oil separator structure (401) while passing through predetermined path. Further, the predetermined maze path of fumes reduces the pressure and increases the separation efficiency by increasing the resistance to fumes causing nominal pressure rise of the powertrain assembly (PA).

[00039] Figure 5a exploded view of the oil separator device (105) as per preferred embodiment where few parts are omitted from the figure. The oil separator device (105) is connected with the oil separator structure (401) (as shown in figure 4) to separate the oil from the oil mist and to release the air through vent hole (507) without oil to atmosphere. The oil separator device (105) comprising of an oil separator case (501) configured to have a filter member (506), an oil separator cover (502). The oil separator cover (502) is detachably attached to an oil separator case (501) through plurality of fasteners (503). As per preferred embodiment the filter member (506) composed of material known in the art like foam type or paper type.

[00040] Figure 5b illustrates the perspective view of the oil separator device (105) as per preferred embodiment, where few parts are omitted from the figure for clarity. The fumes are introduced in the oil separator device (105) through fume inlet hole (508), wherein filter member (506) separates oil from the fumes and said oil is collected in the drain collector (504) through drain collection hole (509) wherein drain collector (504) which is detachably attached to the casing (501) using clamp (505).

[00041] Figure 6 illustrates illustrates the cut section view of the powertrain assembly (PA) across J-J axis as per alternative embodiment. The oil separator structure (401) is configured to have filter member (601) at a predetermined location. As per preferred embodiment, the filter member is disposed near a breather pipe (602). Further, the filter member (601) composed of material known in the art like foam type or paper type. fumes are introduced in the oil separator structure (401), wherein filter member (601) separates oil from the fumes and separated oil from the filter element is returned back i.e. drips into the primary housing (201). Furthermore, separated air from the oil is vented out in to the atmosphere after passing the filter member (601) through the breather pipe (602).

[00042] Thus, the powertrain assembly as per preferred embodiment configured to have two housing i.e. primary housing and secondary housing provided with a single pouring port and single draining port hence the oil filling and oil draining time is less which further reduces the service cost of the vehicle. Furthermore, the oil pouring port is provided on the rear end of the cover member thus ensuring ease of accessibility during service. As the rearmost part of the powertrain assembly is externally visible to the operator and not hindered by the panel members of the vehicle.

[00043] Further, the pressure and oil control system as per preferred embodiment reduces the pressure inside the powertrain assembly which avoids oil seal pop out and ensure optimum temperature and pressure inside the powertrain assembly. The lower control passages below the transmission axis allows both the primary housing and secondary housing to communicate with each other. The lower control passages are provided at the rear most part of the powertrain assembly which maintain optimum level of the oil in the primary housing and secondary housing. Excess oil in the powertrain during churning leads to more power loss since more energy is required to overcome the friction due to more lubricating oil. Hence, adequate quantity of oil is maintained within the powertrain assembly by configuring the oil control passages at least partially below the transmission axis and at the rear most part of the powertrain assembly. Furthermore, the pressure control passage is provided at least partially above the transmission axis specifically at the upmost location such that fumes which are lighter than the oil can escape from the secondary housing towards the primary housing and finally towards the oil separator structure.

[00044] Moreover, as per preferred embodiment the fumes generated within the primary housing and secondary housing is configured to pass through the oil separator structure which has a predetermined profile. The predetermined profile reduces the pressure and increases the separation efficiency by increase the resistance to fumes causing only nominal pressure rise of the powertrain assembly.

[00045] Furthermore, as per preferred embodiment as the oil separator structure is operatively connected to the oil separator device which separates the oil from the fumes and allows the air to escape from the oil separator device thus control the emissions.

[00046] As per alternative embodiment, the filter member is provided within the oil separator structure. The oil separator structure as per alternative embodiment reduces the pressure and temperature further it separates oil from the fumes and allows only air to escape to the atmosphere. Hence, reduces the number of parts which further reduces the cost and weight of the powertrain assembly.

[00047] While the present invention has been shown and described with reference to the foregoing preferred embodiments, it will be apparent to those skilled in the art that changes in form, connection, and detail may be made therein without departing from the spirit and scope of the invention.

List of references
R-R’ - Axis passing through oil separator structure
M-M’ - Axis passing through rear side of powertrain assembly
J-J’ - Axis passing through oil separator structure as per alternative embodiment
FA - Frame assembly
T-T’ -Transmission axis
PA -Powertrain assembly
TS -Transmission system
DSA -Drive shaft assembly
DSRA -Driven shaft assembly
100 - Drive wheel/ Rear wheel
101 - Prime mover/Electric motor
102 - Center stand
103 - Brake system
104 - Cushion member mount structure
105 - Oil separator device
106 - Breather tube
107a – Oil pouring port
107b – Oil drain port
201 - Primary housing
202 - Cover member
203 - Secondary housing
204 - Driving sprocket
205 - Driven sprocket
206 - Transmission means
207 - Drive shaft
208 - Driven shaft
209 - Wheel shaft
210 - Bearing supporting driven shaft
211 - Bearing supporting wheel shaft
212 - Wheel assembly
213 - Drive train oscillation reduction device
214 - Driving gear
301 - Fasteners
302a - Pressure control passage
302b - Oil control passages
401- Oil separator structure
402 - Housing of electric motor
403 - Cooling and guide fins
501 - Oil separator casing
502 - Oil separator cover
503 - Fasteners for oil separator device
504 - Drain collector
505 - Clamp
506 - Filter member
507 - Vent hole
508 - Fume entry hole
509 - Oil exit hole
601 - Filter element
602 - Breather pipe