The present invention relates to a hybrid drive assembly for a motor vehicle, particularly, though not exclusively, for two wheeled motor vehicles, such as, motorcycles, having a swing arm, wherein the engine is separated from secondary transmission, preventing the engine from serving as a load carrying member, thereby reducing the size of the engine and transmission unit, and isolating road shock loads.
In motorcycles with known normal construction a power unit is constructed by integrating an engine with a transmission case which incorporates transmission means such as a CVT for transmitting the engine power to the rear wheel, and a power unit which supports the rear wheel suspended from a vehicle body frame through cushioning.
In vehicles of such a construction, the drive assembly normally comprises a transmission unit interposed between wheel drive shaft and the engine output shaft. The power transmission unit includes a CVT drive for achieving higher transmission efficiency of the vehicle. However the construction of the engine with CVT drive involves a large transmission casing and incurs reduction in transmission efficiency.

The present invention deals with the foregoing problems and allows for providing a drive assembly through a swing arm and a drive wheel that is driven by the internal combustion engine through a power transmission unit replaced with the normal CVT drive, thereby enabling a simple and compact hybrid drive assembly an'd achieving higher transmission efficiency.
In conventional two wheeled automobiles, such as motorcycles, at least one wheel is driven by an internal combustion engine. However, it has become desirable that pollutants discharged from internal combustion engine driven vehicles should be reduced. Thus, the so-called "hybrid vehicle" has become more popular.
Hybrid drive assemblies are normally used in road vehicles such as motorcycles, for enabling the use of two or more different propulsion or drive systems. The solutions proposed are normally a combination of an internal combustion engine and an electric motor, to exploit the advantages and compensate the disadvantages of each.

The main advantage of a combustion engine, and the reason why it is used almost exclusively in road vehicles, is the fuel distance obtainable by virtue of the high energy concentration of the fuel employed. On the other hand, a combustion engine produces harmful emissions, can only operate within a given speed range, thus requiring the use of auxiliary components for meeting the drive requirements.
Moreover, even within the operating range, the efficiency of a combustion engine is fairly low, having variations in the steady-state operation of the engine with considerable increase in pollutant emissions. On the other hand, an electric motor produces no pollution, has a high efficiency of about 80%, and is capable of generating torque on start-up. Application of electric motors to road vehicles is increasing in recent days. However, electric motors are hampered by the limited range of electric batteries currently available; also, the size, weight and cost are factors which are adverse to the application of electric motors to the vehicles.
To eliminate or reduce the drawbacks associated with the use of one type of engine/motor, hybrid solutions of various

configurations have been proposed for enabling alternative or combined use of both the propulsion and drive systems. In a known so-called "series hybrid" combination, the combustion engine serves solely to drive an electric current generator, which charges the batteries powering the electric motor, propulsion being therefore governed exclusively by the electric motor.
This solution provides for a considerable reduction in fuel consumption, by the combustion engine called upon to supply average power, and operating in optimum steady conditions. The construction and various operating factors led to dropping this type of hybrid drive for vehicles.
In the "parallel hybrid" configuration, both the combustion engine and the electric motor are connected to the drive wheels by appropriate transmission mechanisms.
Besides being considerably complex in construction, this type of hybrid drive is not adapted for use in small road vehicles such as scooters. The known hybrid drive assemblies of the type briefly described above are expensive and bulky. Hence there exists a need for

providing a compact and low-cost hybrid drive assembly for two wheeled vehicles.
An object of the present invention is to provide a hybrid drive assembly having a swing arm, wherein the engine is separated from secondary transmission and preventing the engine as a load carrying member, and thereby reducing the size of the engine and transmission unit, and isolating the road shock loads.
Another objective is to provide a simple and compact hybrid drive assembly having a two staged higher efficiency sprocket and chain drive replaced with the CVT drive, and thereby achieving higher transmission efficiency.
Yet another objective of the present invention is to provide a hybrid drive assembly having an electric motor directly mounted on the hub of drive wheel, thereby reducing the transmission efficiency loss when the vehicle running in electric motor mode.
A further object of the present invention is to provide a hybrid drive assembly having a swing arm and a drive wheel that is

driven by both an internal combustion engine through a power transmission unit such as a two stage sprocket and chain drive; and an electric motor mounted on the hub of the drive wheel of the vehicle.
Still a lurther object of the present invention is to provide a hybrid drive assembly having a swing arm connecting the drive wheel to the vehicle frame through shock absorber, thereby effectively with standing the road shocks and allows for smooth riding of the vehicle.
The power pack constituted by the IC engine and power transmission unit is mounted on the swing arm. The swing arm is provided with an L shaped fork-fike structure unit with a set of connecting members tor mounting the engine and the power transmission unit on to it The drive assembiy further comprises a swing arm constructed with a two stage high efficiency sprocket and chain drive as a transmission unit interposed between wheel drive shaft and the engine output shaft.
The power transmission unit includes a two stage chain and sprocket drive; the primary drive transmits the power from the engine crank output shaft to an Intermediate sprocket and the secondary chain drive transmits the power

intermediate sprocket to the wheel drive shaft. This two stage sprocket and chain drive allows for achieving higher transmission efficiency of the vehicle. The swing arm further connects the drive wheel to the vehicle frame through shock absorber.
According to the present'invention, drive assembly also consists of an electric motor mounted on the wheel hub for driving the drive wheel with electric power. The electric motor can be operated instead of or in combination with said internal combustion engine. In this hybrid drive assembly, the drive wheels can be driven by the internal combustion engine or by the electric motor or the both. The electric motor can also be used to regenerate electricity for storage in a battery.
In particular, when the internal combustion engine is activated, the engine transmits motion to the vehicle drive wheel through the chain and sprocket drive mechanism; also the swing arm connects the drive wheel to the vehicle frame through shock absorber, and hence enabling the engine and transmission units of the vehicle to effectively withstand the road shocks and allows for smooth riding of the vehicle.

The provision of the swing arm with two stage chain and sprocket drive allows the engine to be separated from secondary transmission, thus preventing the engine as a load carrying member, and hence reducing the size and cost of the engine with increase in engine life.
When the electric motor is activated, the motor mounted in the wheel hub directly transmits the drive motion to the vehicle wheel, and this prevents the drive motion being transmitted to the internal combustion engine, hence reducing the transmission efficiency loss when the vehicle runs in electric motor mode. In both these configurations the engine and motor present on the vehicle are operated as required.
The features of this invention will now be described with reference to the accompanying drawings which illustrate by way of example and not by way of limitation one of possible embodiments of the hybrid drive assembly proposed herein.
FIG. 1 is a left side view illustrating a two-wheeled vehicle employing the hybrid drive assembly of the embodiment.

FIG. 2 is a rear side view illustrating a two-wheeled vehicle employing the hybrid drive assembly of the embodiment.
FIG. Z is a top view illustrating an engine and transmission layout of the hybrid drive assembly of the embodiment.
FIG. 4 is a front side view illustrating an engine and transmission layout of the hybrid drive assembly of the embodiment.
Referring to FIG 1, left side view illustrating a fwo-wheeled vehicle employing the hybrid drive assembly of the present invention. The vehicle is provided with an improved hybrid drive assembly having an internal combustion engine |1) of power padc P, a swing arm (5( and a drive wheef (4| that is driven by both an internal combustion engine and an electric motor (14) mounted on the hub (f 5} of the drive wheei of the vehicle. The hybrid drive type vehicle includes drive wheel that can be driven by the internal combustion engine or by the electric motor or the both. In this system, the electric motor (14) is used to drive the wbee) /4) as well as to regenerate

electricity for storage in a battery, which further utilized for driving the vehicle.
Referring to FIG 2, a rear side view illustrating a two-wheeled vehicle employing the hybrid drive assembly of the present invention. The swing arm is provided with an L shaped fork like structured unit with a set of connecting members for mounting .the engine and the power transmission unit on to it. The vehicle is provided with a simple and compact hybrid drive assembly having a higher efficiency two staged sprocket and chain drive (6) for achieving higher transmission efficiency. The present invention is intended to provide a low-cost, compact hybrid drive assembly, which can also be used in small, low-cost road vehicles, such as scooters, but which also permits selection of a number of operating modes on the basis of different operating requirements or road conditions.
Further Referring to FIG 3, top view illustrating an engine and transmission layout of the hybrid drive assembly of the present invention. According to the present invention, there is provided a hybrid drive assembly for a vehicle having at least one drive wheel (4), the drive assembly comprising an

internal combustion engine (1); and a transmission unit (2) interposed between a wheel drive shaft (3) of the internal combustion engine (1) and an engine output shaft (7) connected to the drive wheel through the drive and transmission unit (2). The swing arm includes the L shaped fork like structure with connecting members for mounting the engine and the power transmission unit on to it.
The drive assembly further comprises a swing arm (5) constructed with a two staged high efficiency sprocket and chain drive (6) as part of a transmission unit (2) interposed between wheel drive shaft (3) and the engine output shaft (7). The power transmission unit (2) includes a two staged chain and sprocket drive; such that the primary chain drive (10) transmits the power from the engine crank output shaft (8) to an intermediate sprocket (9) and the secondary chain drive (11) transmits the power from the intermediate sprocket (9) to the wheel drive shaft (3). This two staged sprocket and chain drive (6) allows for achieving higher transmission efficiency of the vehicle.
The two staged chain and sprocket drive (6) mechanism includes drive sprockets provided with suitable bearings

such that the drive motion from the wheel shaft are prevented from the wheel to the engine, thereby eliminating the transmission ioss to the internal combustion engine with respect to the hybrid drive arrangements.
Referring to FIG. 4, a front side view illustrating an engine and transmission layout of the hybrid drive assembly constituting the power pack P of the present invention. The swing arm (5) further connects the drive wheel (3) to the vehicle frame through shock absorber (12) and toggle link (13). In particular, when the internal combustion engine is activated, the engine transmits motion to the vehicle drive wheel (4) through the chain and sprocket drive mechanism (6), also the swing arm (5) connects the drive wheel (4) to the vehicle frame through shock absorber (12) and toggle link (13), and hence the enabling the engine and transmission units of the vehicle to effectively with stand the road shocks and allows for smooth riding of the vehicle.
According to the present invention, drive assembly also comprises an electric motor (14) mounted on the wheel hub (15) for driving the drive wheel {4) with the supplied electric power. The electric motor (14) can be operated instead of or in combination with said interna) combustion engine (1). Jn

this hybrid drive assembly, the drive wheels can be driven by the internal combustion engine or by the electric motor or the both, also the electric motor (14) can also be used to regenerate electricity for storage in a battery.
The provision of the swing arm with two staged chain and sprocket drive allows the engine to be separated from secondary transmission and. thus preventing the engine as a load carrying member, and hence reducing the size and cost of the engine with increase in engine life.
In the combustion mode, electric motor is not powered, so that, drive assembly functions are exactly the same way as a conventional drive, the drive from the internal combustion engine is transmitted to the wheel drive shaft through the clutch and two staged chain and sprocket drive mechanism.
When the electric motor is activated, the motor mounted in the wheel hub directly transmits the drive motion to the vehicle wheel, and this enables to prevent the drive motion being transmitted to the internal combustion engine, and hence reducing the transmission efficiency loss when the vehicle running in electric motor mode. In both these

configurations the engine and motor present on the vehicle are operated as required.
The hybrid drive assembly is provided with an internal combustion engine separated from secondary transmission, this allows for preventing the engine to act as a load carrying member, and hence reducing the size of the engine and providing a simple and compact hybrid drive assembly. The provision of two staged higher efficiency sprocket and chain drive replaced with the CVT drive, enables to prevent the drive motion being transmitted to the internal combustion engine, and hence reducing the transmission efficiency loss when the vehicle running in electric motor mode.
In the present hybrid drive assembly the electric motor is directly mounted on the hub of the drive wheel, and hence enabling the hybrid drive for achieving higher transmission efficiency. Also the swing arm connecting the drive wheel to the vehicle frame is provided with a shock absorber and toggle link and hence enabling the hybrid drive to effectively with stand the road shocks and allows for smooth riding of the vehicle.

The hybrid drive assembly of the present invention allows providing a low-cost, compact hybrid drive assembly, which can also be used in small, low-cost road vehicles, such as scooters, but which also permits selection of a number of operating modes on the basis of different operating requirements or road conations.
The various parts of the embodiment are numbered as hereunder:
1. Internal combustion engine
2. Transmission unit
3. Wheel drive shaft
4. Drive wheel
5. Swing arm
6. Two staged high efficiency sprocket and chain drive
7. Engine output shaft
8. Engine crank output shaft
9. Intermediate sprocket

10. Primary chain drive
11. Secondary chain drive
12. Shock absorber
13. Toggle link
14. Electric motor
15. Wheel hub. P Power Pack

We Claim-.
1. A. hybrid drive assembly for a motor vehicle comprising an interna] combustion engine; a transmission unit interposed between a drive shaft of the internal combustion engine and the engine output shaft connected to the drive wheel through the drive and transmission mechanism; a CVT drive; an electric motor directly mounted on the hub of the drive wheel, thereby reducing the loss in transmission efficiency when the veliicle is running in electric motor mode; a swing arm connecting the drive wheel to the vehicle frame through a shock absorber; power pack constituted by the internal combustion engine and power transmission unit mounted on swing arm; and an electric motor mounted on the hub of the drive wheel of tlie vehicle.
2. A hybrid drive assembly as claimed in Claim 1 wherein the swing arm is provided with an L shaped fork-like structure with a set of connecting members for mounting the engine and the power transmission unit on to it
3. A. hybrid drive assembly as claimed in Claim I or Claim 2 wherein the swing arm has a two stage high efficiency

sprocket and chain drive as a transmission unit interposed between wheel drive shaft and the engine output shaft. 4. A hybrid drive assembly for a motor vehicle substantially as herein described with reference to, and as illustrated in, the accompanying drawings,