Claims:We claim:
1. A front drive unit (100) for an electric hybrid vehicle, comprising an engine (102) and an electrical machine (114) with a rotor shaft (112), said engine (102) and said electrical machine (114) are coupled to a differential (108), characterized in said front drive unit (100),
an epicyclic gear assembly (110) coupling said electrical machine (114) to said differential (108), said epicyclic gear assembly (110) comprises a sun gear (1102), a ring gear, at least two planet gears (1104), and a carrier (1106), said sun gear (1102) is coupled to said rotor shaft (112), and said at least two planet gears (1104) are mounted on at least two arms of said carrier (1106) and mesh in between said sun gear (1102) and said ring gear, said carrier (1106) comprises an output shaft (1108) which extends opposite to said rotor shaft (112), and
a drive gear (1110) mounted on and coupling said output shaft (1108) of said carrier (1106) to said differential (108).

2. The front drive unit (100) as claimed in claim 1, wherein said engine (102) is mounted transversely in said vehicle.

3. The front drive unit (100) as claimed in claim 1, wherein said engine (102) is mounted longitudinally in said vehicle.

4. The front drive unit (100) as claimed in claim 1, wherein said electrical machine (114) is operated to assist said engine (102), recuperate energy and drive said vehicle.

5. The front drive unit (100) as claimed in claim 1, wherein said engine (102) is coupled to a transmission (106) selected from a group comprising a Manual Transmission, Semi-Automatic Transmission, an Automatic Transmission, a Dual Clutch Transmission and an Automated Manual Transmission (AMT).

6. The front drive unit (100) as claimed in claim 1 is coupled only to front wheels.

7. The front drive unit (100) as claimed in claim 1, wherein an axle clutch is provided between each of said wheel (116) and said differential (108).

8. The front drive unit (100) as claimed in claim 1, wherein an Electronic Control Unit (ECU) controls the operation of said electrical machine (114). , Description:Field of the invention:
[0001] The present invention relates to a drive unit for a hybrid vehicle and particularly relates to a front drive unit for an electric hybrid vehicle.

Background of the invention:
[0002] There are numerous mechanisms available on integrating motor into transmission of any kind such as Manual, Semi-Automated, Automated, Dual clutch transmission, etc. of a conventional Internal Combustion Engine driven vehicle. By integration of the motor into transmission it is called Parallel hybrid. The reason behind such an integration are many ranging from increasing fuel economy to improving levels of comfort. The existing mechanisms are either generic which gives relative fuel economy comparison with mounting motor at different location or in some case specific mounting locations irrespective of the driven wheels (front mounted or rear mounted engines). Further, the existing mechanisms are general and require a motor with a higher voltage and power level.

[0003] Hence, a new hybrid topology is required which enables a low voltage electrical machine to be integrated to an engine in a modular assembly.

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 front drive unit of an electric hybrid vehicle, according to an embodiment of the present invention.

Detailed description of the embodiments:
[0006] Fig. 1 illustrates a front drive unit of an electric hybrid vehicle, according to an embodiment of the present invention. The front drive unit 100 comprises an engine 102 and an electrical machine 114 with a rotor shaft 112. The engine 102 is coupled to a transmission 106 through a clutch 104. The engine 102 and the electrical machine 114 are coupled to a differential 108. The front drive unit 100 is characterized by an epicyclic gear assembly 110 and a drive gear 1110. The electrical machine 114 is coupled to the differential through the epicyclic gear assembly and a drive gear. The epicyclic gear assembly 110 also known as planetary gear assembly couples the electrical machine 114 to the differential 108. The epicyclic gear assembly 110 comprises a sun gear 1102, a ring gear (not shown), at least two planet gears 1104, and a carrier 1106. The sun gear 1102 is coupled to the rotor shaft 112. The at least two planet gears 1104 are mounted on at least two arms of the carrier 1106 and mesh in between the sun gear 1102 and the ring gear. The carrier 1106 comprises an output shaft 1108 which extends opposite to the rotor shaft 112. The drive gear 1110 is mounted on and couples the output shaft 1108 of the carrier 1106 to the differential 108. The differential 108 is coupled to a pair of front wheels 116. A pair of rear wheels 118 of the vehicle is also shown.

[0007] In accordance to an embodiment of the present invention, the engine 102 is mounted transversely in the vehicle. Alternatively, the engine 102 is mounted longitudinally in the vehicle. The electrical machine 114 is operated to assist the engine 102, recuperate waste energy and drive the vehicle. The Front drive unit/topology 100 is able to do electric driving by switching OFF the engine 102, opening the clutch 104 or putting the transmission 106 in neutral and then powering the electrical machine 114. When the electrical machine 114 drives the vehicle, the clutch 104 is open. The engine 102 is isolated from the transmission 106.

[0008] In accordance to another embodiment of the present invention, the engine 102 is coupled to a transmission 106 selected from a group comprising a Manual Transmission, Semi-Automatic Transmission, an Automatic Transmission, a Dual Clutch Transmission, a Continuously Variable Transmission (CVT), an Automated Manual Transmission (AMT) and the like.

[0009] In accordance to yet another embodiment of the present invention, the front drive unit 100 enables a low voltage or low capacity, such as less than 60V electrical machine 114 (motor/generator) to be fit to the drive gear/pinion 1110 or differential crown with a differential 108 for transversely mounted engine 102. The front drive unit 100 is able to amplify the torque and reduce the speed for maximum use of traction and recuperation. Further, the front drive unit 100 provides dynamic mode change of traction/generation of the electrical machine 114 to suppress drive train oscillation during acceleration and to supplement loss of torque during gear shift for the transmission 106 such as for AMT. The front drive unit 100 reduces the wear of clutch during vehicle launch and phases of partial dry clutch engagements. The front drive unit 100 also enables the low voltage electrical machine 114 to assist the vehicle in modes (e.g. only electric driving, engine assist driving, and all possible modes of re-generation) for improved fuel economy relative to base vehicle configuration.

[0010] In accordance to yet another embodiment of the present invention, the front drive unit 100 is provided in a modular design, which allows the electrical machine 114 to be mounted on to the drive-pinion or differential crown of the transmission 106 having an integrated final drive gear reduction with the differential 108 for the transversely mounted engine 102. Though, a front drive unit 100 is described, a rear drive unit is also possible where the engine 102 is mounted in rear of the vehicle. The modular design of the front drive unit 100 enables the low voltage electrical machine 114 to operate both in the traction mode and generator mode. The traction mode is meant for supplying enough torque to propel the vehicle under electric driving mode and also assist the engine 102 during propulsion. The regeneration mode is meant for capturing all possible energy which is otherwise lost during braking (in the form of heat/friction). The electrical machine 114 is controlled in a dynamic alternative mode between “traction/re-generation” to suppress the oscillations of engine speed rattle during acceleration.

[0011] In accordance to yet another embodiment of the present invention, the front drive unit 100 overcomes torque drops or torque hole during shifting of gears. The front drive unit 100 is operated in instantaneous maximum power mode for short burst duration (which is calculated based on the time for gear shifting at that particular operating point) to prevent any torque drop which is felt by the driver during gear shifts in AMT, and to prevent any discomfort which arises because of clutch slipping in manual transmission with electronic clutch control.

[0012] Normally in the phase of engine idling, the ignition angle is retarded by a few degrees (torque reserve) so that in the event of launch when a sudden increase in torque is needed, the ignition angle is advanced and a large increase in torque appears instantaneously. Also during engine 102 overrun, the ignition angle is first retarded before the fuel is cut off from the engine 102, this ignition angle retard creates a sudden drop of torque from the engine 102 which the driver feels as ‘engine braking’. In the present invention, the electrical machine 114 is capable of providing instantaneous positive and negative torque based on the requirements. So ignition angle is placed at optimum ignition angle unless specifically required such as for heating a catalyst. Further, all vehicle driving behavior (such as launch and sudden braking) is handled by the electrical machine 114. Due to this, combustion is made more optimized.

[0013] In accordance to yet another embodiment of the present invention, the front drive unit 100 is configurable to existing transmissions 106 comprising a Dual clutch transmission (Wet/dry clutch), an automatic transmission (TQ converter), a Continuously Variable transmission (Push/Pull type) intended for both fuel economy and driving comfort.

[0014] In accordance to yet another embodiment of the present invention, the Modular design of the front drive unit 100 allows to operate the low voltage electrical machine 114 in “load point shifting mode” which allows the engine 102 to be shifted to best operating points in terms of Brake Specific Fuel Consumption (BSFC). The operating points of the engine 102 shifts to better BSFC points because of load point shifting.

[0015] The electrical machine 114 of the front drive unit 100 is operated by a controller such as Electronic Control Unit (ECU). The ECU is either a dedicated controller or an existing ECU of the vehicle, such as Engine Control Unit. The ECU is configured to control the electrical machine 114 and comprises an Input/output (I/O) Interface, memory for storing instructions, communication buses, processor and the like. The ECU is interfaced with various sensors of the vehicle through the I/O interface. The sensors comprises a vehicle speed sensor, engine speed sensor, temperature sensor, Manifold Absolute Pressure (MAP) Sensor, gear shift position sensor, and the like. The ECU also detects or measures battery voltage, electrical and mechanical parameters of the electrical machine 114, gear shift intention, and the like. The ECU is configured to receive above inputs, and control the electrical machine 114 in a suitable mode.

[0016] In accordance to yet another embodiment of the present invention, the front drive unit 100 enables autonomous parking. The engine 100 is switched OFF, the clutch 104 is opened or the transmission 105 is set in neutral. A steering wheel with the existing power steering motor or with an additional electrical machine 114 is controlled, followed by powering the electrical machine 114. The ECU controls the electrical machines 114 to park the vehicle autonomously, along with the use of feedback from ultrasonic sensors to gauge the proximity of objects in the environment/surrounding.

[0017] In accordance to yet another embodiment of the present invention, the front drive unit 100 also allows the electrical machine 114 to start the engine 102. The differential 108 is coupled to a front axle to which the two front wheels 116 are mounted. An axle clutch is provided between each wheel 116 and the differential 108. The axle clutch is engaged/closed by default. When the engine is needed to be started, the axle clutch is opened. The electrical machine 114 is activated by the ECU which starts the engine 102 through the transmission and the clutch 104.

[0018] The present invention enables the low voltage (less than 60V) motor/generator integrated into the drive pinion or the differential crown of transversely mounted engine with integrated final drive and differential. The front drive unit 100 reduces shift shocks in automated manual transmission and clutch shudder in Manual transmission with electronic clutch system.

[0019] 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.