Claims:WE CLAIM

1. A dynamically constrained high speed transmission drive system for electric vehicle for transmission of power from a rotating shaft to wheels comprising :-

- a pair of nested toothed entities both moveable during power transmission such that the first entity is positively attached to the motor shaft in the prime mover side and with a fixed rotational axis and with the moveable second entity having inner toothed surface meshing continuously with outer toothed surface of the first entity and with the outer toothed surface of the second entity connected to load side via a drive transmission member such as chain, belt, rope or any known power transmission media

characterized in the nested arrangement of the two entities and wherein the second entity is dynamically constrained to mesh with first entity, thereby resulting in auto adjustment to negate slackness of transmission member.
, Description:FIELD OF INVENTION

The present invention relates in general to transmit power with belt/chains between two rotating shafts and more particularly to an electrical power transmission unit for two-wheel vehicles.

The present invention relates to a power transmission system, such as for an electric automobile/vehicle using an electric motor as a drive power source or an electric automobile/vehicle using a fuel engine (an ordinary engine making use of an explosion of fuel) and an electric motor both as a drive power source and to an operation method for a same.

The present invention accordingly relates to a transmission system and more particularly to a transmission system for an electric vehicle.

The invention relates specifically to a transmission system of a vehicle consisting of gearbox, a differential, a drive shaft and at least two-wheel axles. The transmission system is used to deliver power from the motor (the engine of fuel vehicle or a drive motor of an electric vehicle) to the drive wheels and thus driving the vehicle to move.

DESCRIPTION OF PRIOR ART

Two wheel vehicles of the type using gasoline engine as drive source are mainly available at present. However two wheel vehicles of the type using an electric motor as a device source are in demand in many developed countries including India and more so in urban areas where the exhaust gases control are predominant. Thus in view of the environmental protection and also in view of resources conservation, the trend in two wheel vehicles development is to design power transmission units actuated by electricity in place of existing two wheel vehicles that use gasoline.

There are many patents related to two-wheel electrical vehicles. The inventors believe that those patents taken alone or in combination neither anticipate nor render obvious the present invention.

Further with the advent of higher speed prime movers like small sized IC engines, Gas turbines and Motors for Electric vehicles and low speed prime movers like wind mill rotors, there is a need to change the rotational speed to usable limits based on final applications. This is complicated by the need to have packagable solutions which are light weight, reliable, cost effective, energy efficient and simple in operation. Standard gear boxes need the use of flexible couplings to accommodate relative motion between the prime mover and wheels. Two wheelers use chains which are limited by speed-power combinations. This invention circumvents these problems by providing a simple and innovative solution for flexible power transmission.

The illustration of prior art is illustrated in fig. 10. Conventional Power transmission system consists of a smaller toothed entity and a larger toothed entity (Fig. 10). One of the entities is connected to a shaft on prime-mover side and the other entity is connected to a shaft on load side. The axis of both the entities is fixed. The ratio of diameters of the two entities depends on speed and torque as demanded by the application. Power is transmitted from prime mover side to load side through the media like belts, chains, ropes etc which meshes with the entities as they rotate.

In general, the surface speed of the entities is limited to suit the operating regime of power transmitting media through the introduction of reduction gears between the prime mover and the entity. Usage of gear box increases the cost of transmission system and also makes the system heavier and less energy-efficient in power transmission. Also, with usage, the power transmitting media like chains gets elongated due to wear and frequent manual adjustments are required to maintain appropriate length of media between the entities.

SUMMARY OF THE INVENTION

There is according a need for an electric power transmission unit for two-wheel vehicles that overcomes the disadvantages of the known types of electric two-wheel vehicles.

It is therefore an objective of the present invention to provide an electric power transmission unit for two-wheel vehicles allows power transmission flexibly from a rotating shaft to a point of power consumption by a dynamically constrained toothed transmitted entity pair which permits transient positional shifts between the points of power generation and consumption during power transmission.

In conventional electric automobile/vehicles, an electric motor is connected directly to the wheels.

The present invention is made with such points in view. It therefore is an object of the invention to provide a power transmission system with a compact size, light weight and well adaption for vehicle-mounting.

Therefore this invention remedies the above drawbacks and particularly provides a simple but extremely efficient arrangement. Thus the invention has disclosed a solution to solve the problems of prior art suffering and aims to provide a structure which is light weighted and efficient.

Power transmission

A simple means to change rotational speed while transmitting power, through the interaction of two toothed entities characterized by one of the entities being dynamically constrained purely by contact between teeth, rotating about different axes (Fig. 1) such that:
• One entity is nested inside the other
• One of the entities is free to rotate about a fixed axis
• The inner surface of the larger entity and outer surface of the smaller entity are toothed.
• The external surface of the internal entity engages circumferentially and constantly with the internal surface of the external entity through teeth so as to transfer rotational movement positively.

BRIEF DESCRIPTION OF THE DRAWINGS

Although the characteristic feature of the invention will be disclosed wholly in the specification and will be particularly pointed out in the claims, the invention itself, and the manner in which it may be made and used may be better understood by referring to the following description taken in connection with the accompanying drawings forming part hereof, wherein the like reference numerals refer to like parts through the several views which are illustrated in fig. 1 to 10.

Fig. 1 illustrates the invention with two toothed entity

Fig. 2 illustrates Grooved outer periphery

Fig. 3 illustrates Permitted axis movement

Part no. Part name
31 Permitted axis movement

Fig. 4 illustrates floating entity which is internally meshed with smaller entity on prime mover side

Fig. 5 illustrates toothed pair not in motion and held in place by peripheral covers on either faces of the pair

Fig. 6 illustrates types of nested entity and inner entity has an outer toothed surface which may be straight or contoured.

Fig. 7 illustrates outer periphery is used to lift loads
w = load

Fig. 8(a) illustrates The shown degree of freedom are dynamically constrained when loaded with chain/belt/rope drive

Fig. 8(b) illustrates Dynamically constrained by the drive element under tension F

Fig. 9 illustrates power transmission flexibly from a rotating shaft to a point of power consumption by a dynamically constrained toothed transmitting entity pair

Part no. Part name
91 Power Source Side
92 Load Side
93 Entity-2 (position 1)
94 Entity 1
95 Entity-2 (position 2)
96 Entity-2 (position 3)
97 Tension side

Fig. 10 illustrates relationship between the two entities, first entity (102), second entity (104), fixed axis (101) and the power transmission path/media (103).

Part no. Part name
101 Fixed axis
102 Entity-1
103 Power transmitting media
104 Entity-2

The invention discloses the following with illustration in the accompanying drawings :-

• A means to transmit shaft power in limited space with minimum number of parts while additionally changing speed (Fig. 1)
• An embodiment where the outer periphery of the larger toothed entity is also toothed. (Fig. 2)
• An embodiment where the outer periphery of the larger toothed entity is in the shape of a pulley or grooved. (Fig. 2)
• An embodiment where the axes of the toothed entities are angular w.r.to one another when transmitting power. (Fig. 3)
• An embodiment where the axes of the toothed entities can move w.r.to each other when transmitting power. (Fig. 3)
• An embodiment where one of the entities is splined, keyed or otherwise positively attached to the motor shaft. A typical splined construction is shown in Fig. 4.
• An embodiment where the inner entity has an outer toothed surface which is straight or contoured. (Fig. 6)
• An embodiment where the outer periphery is used to lift loads. (Fig. 7)
• An embodiment wherein one of the entity is not completely constrained in space when not loaded but is fully constrained by application of chain/belt tension load when in motion.(Fig. 8(a) and Fig. 8(b))
• An embodiment wherein one of the entities is dynamically constrained to mesh with another entity with fixed rotational axis. The resulting pitch point can be at any location on the pitch circle of the entity with fixed-rotational axis depending on the length of the drive element which can be a chain, belt, rope or other power transmitting media. (Fig. 9)
• An embodiment wherein one of the entities is dynamically positioned as mentioned earlier resulting in auto adjustment to negate slackness of transmission member like belts, chains, rope etc due to wear during power transmission thereby eliminating the need for manual adjustment of sprocket/gear position to accommodate increase in length due to wear.

Novelty and Inventive step of the present invention is described herein :-

The invention relates to an electric motor vehicle using a motor as a drive motive power and particularly to an electric motor vehicle which is preferably applied to two wheelers such as motorcycles and scooters. Incidentally the electric motor vehicle is also demanded to have its safety improved together with the improvement of its performance.

Purely electric motor driven vehicles require compared to the conventional internal combustion engine powered drive train fewer gears because the electric motor already delivers out of state torque and has a respect to the internal combustion engine wider speed range. However input gear boxes are not sufficient for electric motor driven vehicles in any case. Purely electric motor driven vehicles are limited then by speed limits which are low and undesirable. Multispeed transmissions, in cooperation with an electric motor, have the advantage of a higher end speed of the vehicle as well as more frequent operation in a high efficiency range of the electric machine map. An increase in range is one of the most important development challenges of purely electro motor vehicles. Another challenge is the power shiftability of the transmission because torque interruption during the circuit in purely electric motor vehicles reduces the ride comfort and is not desired by the end customer.

The inventive design of the nested arrangement allows a compact design of the transmission and offers a higher flexibility in the choice of gear ratios.

In the proposed system, the reduction in speed is enabled through the use of a floating entity which internally meshes with smaller entity on prime mover side. This arrangement eliminates the need for usage of a gear box and thus the mass of the system is optimised and is more energy efficient.

The dynamically constrained entity adjusts its position automatically according to the elongation of power transmitting media due to wear, thereby eliminating the need for manual adjustment of the media.

The proposed means allows power transmission flexibly from a rotating shaft to a point of power consumption by a dynamically constrained toothed transmitting entity pair which permits transient positional shifts between the points of power generation and consumption during power transmission. The toothed pair, when not in motion, is held in place by peripheral covers on either faces of the pair (Fig. 5).

The transmission system for an electric vehicle in accordance with the present invention comprises a gear arrangement which produces different rotation ratio between a drive motor and drive wheels during running of the electric vehicle, and the advantage of the present invention over the prior art is that with the “nested arrangement” as disclosed in the specification.

The invention exhibits the features of compact conformation, easy to connect, transmission is simple but reliable and overall weight is light.

While the electric power transmission unit for two wheel vehicle herein described constitutes preferred embodiments of the invention, it is to be understood that the invention is not limited by this precise structural description and changes may be made therein without departing from the scope and spirit of the invention as defined in the appended claims.

The invention has been described as detailed above but various embodiments and variations are possible beyond the preferred embodiments disclosed in this document. All such variations and modifications as obvious to the skilled person is within the scope of this invention.