FORM 2 THE PATENTS ACT, 1970 ( 39 of 1970 )
COMPLETESPECIFICATION SECTION 10
TITLE

OPERATED ROAD VEHICLE'
APPLICANT
BAJAJ AUTO LIMITED, an Indian Limited Company, of Akurdi, Pune 411 035, Maharashtra, India
The following specification particularly describes the invention and the manner in which it is to be performed



This invention relates to/. & • in electrically operated road vehicle;. This invention is
particularly related to drive system of a small vehicle such as two or three wheeled electrically operated ones. F;or simplicity of explanation, such vehicles are termed as 'EVs' in the subsequent paragraphs in this specification.
The road vehicles as obtained today have Internal Combustion engine (ICE) as the power plant. Due to the torque and speed characteristics of such a power plant, a matching Gearbox with multiple gear ratios, usually 4 or 5, is necessary to obtain required performance, such as acceleration, speed and driveability of the road vehicle. Such road vehicles also need to use a Clutch mechanism to disengage the engine from the Gearbox during gear-shifting for smooth operation, and. when the vehicle is at rest to prevent the engine from stalling.
In the case of conventional EVs. due to inherent torque and speed characteristics of an electric Motor, and as governed by a Controller, multiple ratio Gearboxes are not functionally required to be used. However, due to the absence of such multiple gear ratios, a compromise on size, performance and efficiency is needed to cater to diverse range of torque and speed needed to meet the required performance of the road vehicle such as acceleration, speed and driveability. Such drive systems arc characterized by a large bulk and lower efficiency of the drive system, leading to higher consumption of electrical energy and'reducing the effective range of the EVs per battery charge.

To overcome this problem, occasionally, solutions such as coupling the electric Motor to the a conventional 4 or 5 speed ICE Gearbox have been attempted. These designs, due to ease of availability and lower cost, generally use gear ratios as obtained in conventional ICE vehicles and also continue to use a clutch or similar system for facilitating a smooth gear ratio change. Moreover gear-shifting has to be done manually by the driver, and which will not yield optimal efficiency and performance.
In some instances, solutions, such as matching the electric Motor to a conventional automatic shifting multiple ratio Gearbox or a continuously variable transmission system has been attempted.
Further, in the known EVs, the Controller and the electric Motor are separate units, assembled at different places on the vehicle. In some of known EVs, the Controller is mounted on the bracket, which is fixed. for instance, to the Motor. The Controller and the Motor are connected together by electric wires. The Controller and the Motor have their own cooling arrangements to dissipate heat generated during operation. EVs having manual gear selection also use a clutch mechanism, connected to the Gearbox, for the purpose of disengaging the power from Motor to the Gearbox during selection of the gear.
The output of the Motor or Gearbox (if used) is connected to the driving wheels of the vehicle through shafts and such other appropriate mechanisms.
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One of the disadvantages experienced in the prior art EVs described above is the bulky size of the drive system since the Controller. Motor and a Gearbox are separate units.
Yet another disadvantage of the prior art vehicles is the complexity and cost of the electrical interconnection of the separate systems such as Controller. Motor by cables, and also their mounting by means of separate brackets.
Yet another disadvantage of the prior art EVs is the lower electrical efficiency due to non-optimal gear ratios.
Yet another disadvantage of the prior art EVs is its poor thermal properties due to limited area for heat dissipation, and necessity therefore, of separate heat dissipation arrangements, leading to additional bulk and cost.
Yet another disadvantage of the prior art EVs is that the cost of the drive system is high, as multiple units have to be separately housed, sealed, and installed on the vehicle.
Yet another disadvantage of the prior art EVs is the reliability of the system as a whole is reduced because of separate units such as Controller. Motor and a Gearbox, if used, need to be externally interconnected.
Yet another disadvantage of the prior art EVs is the need to externally connect various power ancillaries such as DC-DC converters and high power Contactors by means of thick electrical cables, to the
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Controller- battery etc. thereby increasing cost and reducing system efficiency.
To overcome the above-mentioned difficulties, we have invented a compact drive system for EVs.
One of the objectives of the present invention is to have a compact drive system for EVs that has an integrated Controller. Motor, Gearbox and power ancillaries.
Yet another objective of the present invention is to minimize the number of gear ratios in the Gearbox by optimum design of Controller and Motor.
Yet another objective of the present invention is to maximize the electrical efficiency of the system by optimum design of Motor and Controller.
Yet another objective of the present invention is to increase the thermal efficiency of the system by interconnecting the housing of the Controller and Motor to achieve good heat dissipation.
Yet another objective of the present invention is to increase the reliability of the drive system by reducing external electrical interconnection between the various units.
Yet another objective of the present invention is to increase the reliability of the drive system by reducing the temperature rise due to good heat dissipation.
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Yet another objective of the present invention is to incorporate electrical synchronisation for smooth shifting of gears and eliminate the use of clutch in the drive system.
Yet another objective of the present invention is to have the option to incorporate electrical gear-shifting along with electrical synchronisation for smooth shifting of gears for less driver fatigue.
Yet another objective of the present invention is to have the option to incorporate automatic gear-shifting, along with electrical synchronisation, for optimal performance and smooth shifting of gears for increased system efficiency.
Yet another objective of the present invention is to minimize the cost of the drive system for EVs by eliminating a number of independent units, with separate packaging and their interconnections.
This invention provides an improved power train system used in electrically operated road vehicle essentially comprising of an integrated drive system having the Controller, a Motor and a Gearbox; said Controller being a mechanically sturdy casting with integrated heat dissipation surfaces for better heat dissipation and being secured onto said Motor by one or more fasteners which allow conduction of excess heat from said Controller to the housing of said Motor and providing the desired environmental protection.
In the above input power train system, the Controller is provided with independent electrical feedback from output shaft of said Gearbox
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arid said Motor. The said Controller synchronizes with the speed of the Motor shaft and input shaft during gear shifting, for smooth engagement of gears without gear dashing.
In the Gearbox of the improved power system there is provided t\vo gear ratios, optimally chosen to match said Motor and said Controller, to obtain the desired envelope for vehicle performance, said Gearbox being further provided with three or more gear ratios, if required, to obtain different levels of vehicle performance.
In the improved power train system, said Gearbox is provided with means for automatically actuating gear shift, said means being actuated by said Controller, based on desired performance of the vehicle and the capabilities of the drive system.
The Controller of the improved power train system is mounted onto said Motor for electrical interconnection without any physical external cables, and wherein DC-DC converters and high power contactor are built into said Controller for reducing the number of components and their external interconnection.
In the improved power train system, the Motor is permanently connected to the input shaft of said Gearbox.
The compact drive system for EVs will now be explained in detail w'ith reference to accompanying figures wherein:
• Figure 1 shows a drive system of an EV as per the prior art.
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• Figure 2 shows the improved compact drive system of an EV according to the invention.
• Figure 3 Illustrate an exploded view of a typical improved compact drive system of an EV according to the invention
The compact drive system of the EVs according to the invention essentially comprises of an integral drive system (10) comprising of Controller (11), a Motor (12), and a Gearbox (13); the said Controller further comprising of a Controller housing (31) and an electronic assembly (30); the said Motor (12) further comprising of Motor housing (26). a stator (27), a rotor (28) and a Motor cover (29); the said Gearbox (13) further comprising of a first Gearbox half (21), a second Gearbox half (22). a pair of Primary gears (23). a pair of Intermediate gears (25). a Final drive (24) and a Gear shifter (33).
With reference to the Figure 1, the Controller (1) powered by the vehicle battery (not shown) is mounted on the bracket (5). which is attached to the housing of the Motor (2) through fasteners such as bolts. The Controller is electrically connected to the Motor through the power cable (7) and a control cable (6). Based on signal input from the accelerator control in the vehicle (not shown) operated by the driver, the Controller (1) commands the Motor to run at a desired speed and deliver the necessary' torque at its output shaft (not shown) by transmitting electric power through the power cable (7). To ensure proper operation of the Motor (2), the Controller (1) obtains feedback from the Motor (2) through the control cable (6).
The clutch (4) is mounted on the output shaft (not shown) of the Motor (2) transmits mechanical power from the Motor (2) to the Gearbox
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(3) and the wheels (not shown) are driven by the output shaft (8) of the Gearbox (3).
The torque of the output shaft (not shown) of the Motor (2) is converted to torque at the output shaft (8) of the Gearbox (3) by multiple Gearbox ratios as selected by the driver. The clutch (4) has to be manually operated by the rider for synchronisation of the speed of the Motor shaft and input shaft (not shown) of the Gearbox for smooth engagement of gears without gear clashing. To obtain desired road end driveability performance, four or more gear ratios are required.
As can be clearly seen, the Controller (1), Motor (2) and the Gearbox (3), clutch (4) control cable (6). and power cable (7) are separate units connected mechanically making the drive system bulky. Figures 2 and 3 illustrate compact drive system of an EV according to the invention and as applied to a typical three-wheeled vehicle.
With reference to the figures2 and 3. the drive system of the TVs. as per the invention, comprises of an integrated drive system (10). comprising of Controller (11), Motor (12) and Gearbox (13).
The Controller (11). consists of a Controller housing (31), which is a mechanically sturdy casting with integrated heat dissipation surfaces (32) for better heat dissipation. The said Controller housing (31), is secured on to the said Motor cover (29) by fasteners (not shown). The Controller (11) is further assembled with said electronic assembly (30). which in turn comprises essentially of a circuit board, bus bar assembly, power ancillaries such as DC-DC converters, high power contactors etc. (not separately demonstrated.)
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The Motor (12) comprises of Motor housing (26), which houses said stator (27) and the rotor (28) and is covered by Motor cover (29). The said rotor (28) is mechanically connected and drives the said coupler (32). The said coupler is housed in said second Gearbox half (22).
The said Gearbox (13) comprises of said first Gearbox half (21) and said second Gearbox half (22) joined together by fasteners (not shown). The said second Gearbox half (22) is fixed to the said Motor housing (26) by means of fasteners (not shown). This formulates the assembly in which the transmission gears are located. The transmission gears are a pair of primary gars (23), which can be selected by means of gear shifter (33). The said pair of primary gears (23) is in mesh with said pair of final drive (24) through said pair of intermediate gears (25), The power from Motor is transmitted to output shaft through said coupler, one of the gears of said pair of primary gear (23) as selected, one of the gears of said pair of intermediate gears (25) and the said final drive (24) to output shaft (not shown). The power is then transmitted to the wheels for driving the vehicle.
The Controller (11) is provided with independent electrical feedback of the vehicle wheel speed from the output shaft of the Gearbox
(13) through a electrical speed pick up unit (not shown) to which it is connected. Based on signal input from the gear shift control (not shown) operated by the driver, the gear shifter detector (34) and its associated electronics (not shown), provides a signal to the Controller (11) which synchronizes the speed of the Motor shaft and which is connected to the input shaft (not shown) of the Gearbox (13) with that of the output shaft
(14) for smooth engagement of gears.
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Controller characteristics, the Gearbox can be provided with 3 or more number of gear ratios.
In another embodiment of this invention the Gearbox is additionally provided with a Motorized drive unit (now shown), mounted on the said gear shifter meschnism of the said Gearbox and driven from a signal from the Controller (11) and an gear shifter switch (not shown) operated by the driver, thus al lowing smooth gear-shifting, with minimal driver effort and fatique.
In another embodiment of this invention, the electric gear shift system as above can be adopted to be automatically actuated as determined and commanded by the Controller (11), based on desired performance of the vehicle and the capabilities of the drive system.
The improved compact drive system for Electrically Operated Road Vehicles as described herein and as illustrated in the drawings accompanying herewith and having variations and modifications are within the scope of the present invention. Such modification and variations are well within the knowledge of a person skilled in the art without deviating from the scope of the invention.
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WE CLAIM:
.1. . An improved integrated drive system (10) used in
electrically operated road vehicle comprising Controller (11), a Motor (12) and a Gearbox (13); said Controller being located within a Controller housing (31) and an electronic assembly (3.0); the said Motor <12) further comprising of Motor housing (26), a stator (27), a rotor (2S) and a Motor cdver (29); the said Gear"-box; (13) further comprising a first Gearbox half (21), a second Gearbox half (22) , a pair of primary gears (23), a pair of intermediate gears (25), a pair of final drive (24) and a gear shifter (33); the said Controller housing (31) being a mechanically sturdy casting with integrated heat dissipation surfaces for better heat dissipation and being secured onto said Motor housing (26) which allows conduction of excess- heat from said Controller to the housing of said Motor and al lows elimination of the electrical connections end provides desired environmental sealing; the said Motor housing (26) being assembled to the said second Gearbox half (22) to achieve compactness.
!2. An improved integrated drive system as claimed in Claim .1 wherein said Controller (.11) is provided with independent electrical feedback from output shaft of said Gearbox (13) and said Motor (12).

3- An improved integrated drive system as claimed in Claim
1 or 2 wherein said Controller (11) synchroni zes with the speed of said Motor shaft and input shaft of said Gearbox (1.3) for smooth engagement of gear without clashing.
4. An improved integrated drive system as claimed in any of the preceding claims wherein said Gearbox of drive system comprises two gear ratios optimally selected to match said Motor and said Controller to obtain desired vehicle performance.
5. An improved integrated drive system as claimed in Claim 1 wherein the said Gearbox is provided with 3 or more gear ratios to obtain different levels of vehicle performance.
6. An improved integrated drive system as claimed in Claim 1. wherein said gear shifter (33) is actuated by said control ler (11) for automatic gear shift based on desired vehicle
performance and capabilities of the drive system.
7. An improved integrated drive system as claimed in Claim 1 wherein said Controller is mounted onto said motor for electrical interconnection without having any external cables.
8. An improved integrated drive system as claimed in Claim 7 where in DC-DC converters and high power contractor are built into said Controller for reducing the number of components and their interlinking.