Claims:We claim:
1. An drive assembly (102) for a series hybrid vehicle (100), said vehicle (100) comprising an Internal Combustion engine (104), a first electrical machine (106) coupled to a crankshaft of said engine (104), at least one second electrical machine (110) coupled to a wheel (130) of said vehicle (100), and a battery (108) connected to said first and second electrical machines (106, 110), characterized in that,
said at least one second electrical machine (110) coupled to at least one wheel (120, 130) of said vehicle (100) to drive said vehicle (100).

2. The drive assembly (102) as claimed in claim 1, wherein said at least one second electrical machine (110) is coupled to a hub of said at least one wheel (120, 130).

3. The drive assembly (102) as claimed in claim 1, wherein said at least one second electrical machine (110) is directly coupled to a wheel shaft (114) of said at least one wheel (120, 130).

4. The drive assembly (102) as claimed in claim 2, wherein said at least one second electrical machine (110) is coupled to said wheel shaft (114) through a clutch (122).

5. The drive assembly (102) as claimed in claim 2, wherein said at least one second electrical machine (110) is coupled to said wheel shaft (114) through a secondary shaft (116), and said secondary shaft (116) is coupled to said wheel shaft (114) through a first reduction unit (118).

6. The drive assembly (102) as claimed in claim 5, wherein said at least one second electrical machine (110) is coupled to said secondary shaft (116) through a second reduction unit (128).

7. The drive assembly (102) as claimed in claim 5, wherein said at least one second electrical machine (110) is coupled to said secondary shaft (116) through a clutch (122).

8. The drive assembly (102) as claimed in claim 1, wherein said at least one second electrical machine (110) is mounted beside said at least one wheel (120, 130).

9. The drive assembly (102) as claimed in claim 1, wherein said first electrical machine (106) charges a battery (108), and said battery (108) powers said second electrical machine (110) to drive said vehicle (100).

10. The drive assembly (102) as claimed in claim 1, wherein said vehicle (100) comprises a two-wheeler, a three wheeler, a four wheeler and the like.
, Description:Field of the invention:
[0001] The present invention relates to hybrid vehicle architecture and particularly relates to operating strategy for a series hybrid vehicle or also called as range extender.

Background of the invention:
[0002] According to a patent literature 0011/DEL/2013, a vehicle with hybrid power system is disclosed. A motorcycle having at least one seat and at least two wheels, an internal combustion engine, a generator, and a rechargeable battery configured to be recharged by the internal combustion engine or generator, an electric motor connected through an electronic controller, electrically connected to the rechargeable battery and configured to drive at least one of a plurality of wheels of the vehicle, and an electronic controller configured to start the internal combustion engine based upon a monitored condition of the rechargeable battery.
[0003] Though a series hybrid vehicle is disclosed, but a specific drivetrain or drive assembly is not disclosed. Hence there is a need for a specific drive assembly for efficient series hybrid topology in a vehicle.

Brief description of the accompanying drawings:
[0004] An embodiment of the disclosure is described with reference to the following accompanying drawing,
[0005] Fig. 1 illustrates a block diagram of a drive assembly for a series hybrid vehicle, according to an embodiment of the present invention;
[0006] Fig. 2 illustrates a second variant of the drive assembly, according to the embodiment of the present invention;
[0007] Fig. 3 illustrates a third variant of the drive assembly, according to the embodiment of the present invention;
[0008] Fig. 4 illustrates a fourth variant of the drive assembly, according to the embodiment of the present invention, and
[0009] Fig. 5 illustrates a fifth variant of the drive assembly, according to the embodiment of the present invention.

Detailed description of the embodiments:
[0010] Fig. 1 illustrates a block diagram of a drive assembly for a series hybrid vehicle, according to an embodiment of the present invention. The drive assembly 102 for a series hybrid vehicle 100 is disclosed. The vehicle 100 comprises an Internal Combustion engine 104, a first electrical machine 106 coupled to a crankshaft of engine 104, at least one second electrical machine 110 coupled to a wheel 120, 130 of the vehicle 100, and a battery 108 connected to the first and second electrical machines 106, 110. The frame or chassis is not shown for simplicity in understanding. The frame is used to hold and keep the aforementioned components in a specific position. The drive assembly 102 is characterized by at least one second electrical machine 110 coupled to at least one wheel 120, 130 of the vehicle 100 to drive the vehicle 100. The at least one wheel comprises a front wheel 120, and a rear wheel 130.
[0011] The vehicle 100 is any one selected from a group comprising a two-wheeler such as motorcycle, scooters, mopeds etc., a three-wheeler such as Auto-rickshaws, a four wheelers such as cars, and the like.
[0012] The first electrical machine 106 is a generator which is run by the engine 104 to charge the battery 108. The first electrical machine 106 also functions as a starting device for the engine 104 by motoring the engine 104 to optimal starting speed. The first electrical machine 106 is provided with a first control unit (not shown). The second electrical machine 110 is a drive motor. Similarly, the second electrical machine 110 is provided with a second control unit (not shown). In an embodiment of the invention, a single control unit can control both the first and second electrical machines (106, 110). The battery 108 is provided with a Battery Management System (BMS). An Engine Control Unit (ECU) 112 is provided to control the operation of the engine 104. The First control unit, the second control unit, the BMS and the ECU 112 all are interconnected for the optimal operation of the vehicle 100. In the Fig. 1, the second electrical machine 110 is shown directly coupled/mounted to a wheel shaft 114, and to a left side of the rear wheel 130 of a two-wheeler vehicle 100. The second electrical machine 110 is also mountable to right side of the at least one wheel (120, 130).
[0013] Fig. 2 illustrates a second variant of the drive assembly, according to the embodiment of the present invention. The second variant comprises at least one second electrical machine 110 coupled to a hub of the at least one wheel 120, 130.
[0014] Fig. 3 illustrates a third variant of the drive assembly, according to the embodiment of the present invention. The third variant comprises at least one second electrical machine 110 is coupled to the wheel shaft 114 through a clutch 122. The clutch 122 enables to engage and disengage the second electrical machine 110 to the wheel shaft 114.
[0015] Fig. 4 illustrates a fourth variant of the drive assembly, according to the embodiment of the present invention. The fourth variant comprises the at least one second electrical machine 110 coupled to the wheel shaft 114 through the secondary shaft 116. The secondary shaft 116 is coupled to the wheel shaft 114 through a first reduction unit 118. The first reduction unit 118 comprises at least one of a gear drive, a belt drive, a chain drive and the like. In the Fig. 4, the first reduction unit 118 is shown to be having two gears of same / different sizes intermeshing with each other. One gear is mounted on the wheel shaft 114 and the other gear is mounted on the secondary shaft 116. By changing the type, size of gears, a desired torque and drivability of the vehicle 100 is obtained.
[0016] Fig. 5 illustrates a fifth variant of the drive assembly, according to the embodiment of the present invention. The fifth variant comprises the at least one second electrical machine 110 coupled to the secondary shaft 116 through a second reduction unit 128. The second reduction unit 128 is similar to the first reduction unit 118 as explained above.
[0017] In the variant where a secondary shaft 116 is present, the second electrical machine 110 is mountable to the secondary shaft 116 through a clutch 122. In yet another variation, the at least one second electrical machine 110 is mounted beside the at least one wheel 120, 130. The first electrical machine 106 charges the battery 108. The battery 108 powers the second electrical machine 110 to drive the vehicle 100.
[0018] The engine is operated at best Brake Specific Fuel Consumption (BSFC) operating conditions thus enabling optimal usage of the fuel. The engine is operated to charge the battery and also controlled to by-pass the battery and supply the entire energy generated directly to the motor and thus enabling very less use during a drive cycle, thereby increasing the life of the engine. Since, the engine is operated at best BSFC, a smaller size engine is possible leading to downsizing the engine and saving space in the vehicle for other components. Since, the engine is operated at constant operating points, a less complex EMS is used, saving further costs. The engine can be made to run in a traditional carburetor or with an electronic carburetor by keeping the emission in control.
[0019] The mounting of the motor overcomes the gyroscopic effect at high speeds as it is not rotating along with the wheel like the in hub electric motors and hence enable better efficiency and also the mounting location ensures improved stability of the vehicle. The motor is positioned close to the wheel. Very minimal coupling reducing the cost further. The mounting positions provides different variations to allow placing the motor as per the design of the two wheeler vehicle. Easy serviceability and maintenance.
[0020] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.