The present invention relates to electric vehicles and particularly but not exclusively to the requirement for emission (exhaust and noise) free transport having adequate range, performance and practicality for safe everyday use by a person without specialist knowledge or skills.

Air pollutants emitted by road vehicles form a significant proportion of the so called "greenhouse" gases produced world-wide claimed to be responsible for global wanning. The toxic gas content is responsible for forest erosion, water pollution, ozone depletion and ill health of humans and animals, and particulate emissions are also responsible for ill health, particularly with respect to cancer development and athsma. Air pollution in towns and cities caused by road vehicle emissions is reaching such levels that governments are beginning to ban the use of pollutant emitting vehicles either at specific times, when pollution levels exceed set limits or, more rarely, totally.

Currently, the most practical solution to the provision of emission free road transport is the use of vehicles driven by electric motors powered by batteries. The main factor affecting the range, performance and practicality of such vehicles lies with the batteries in as much as the storage of electrical energy incurs a substantial weight penalty.

There are, however, financial and other advantages associated with the use of electric vehicles, often capitalised upon by operators of utility and fleet vehicles, such as substantially reduced fuel costs, reduced maintenance and down-time due to the simplified nature of such vehicles and greater longevity. In addition, electrically driven vehicles are substantially quieter than those powered by internal combustion engines.

An electric vehicle has to be designed so as to operate on a small percentage of the energy normally available to a road vehicle, whilst subject to a substantial weight penalty if a reasonable range is to be achieved. For practicality, it must have a performance and range acceptable to the average user i.e. reasonable acceleration, a maximum speed of at least sixty kilometres

per hour, normal load carrying capacity, a range that usually requires the battery to be recharged no more than once a day and a facility for rapidly recharging the batteries, should this be required. It is also essential that the vehicle is safe both to use and in the event of an accident.

According to the invention, there is provided a scooter having a step- through chassis, the chassis defining a battery compartment substantially wholly within the chassis and sufficiently large to house an adequate number or size of batteries to provide motive power for the scooter, at least some of the batteries being housed beneath the footplate.

Preferably the chassis comprises elongate structural members extending forward and backward along the scooter, the battery compartment being formed therebetween. Sheet members may extend between the structural members to define the battery housings, and are preferably of metal.

The invention also provides a vehicle comprising a drivable axle and a transmission system operable, in use, to drivingly connect the drivable axle and an internal combustion engine, the vehicle comprising an electric motor operable to provide drive to the transmission system in place of an internal combustion engine and the vehicle being otherwise substantially unaltered.

Preferably the vehicle is a two wheeled vehicle, such as a scooter. The electric motor may be a pancake motor.

The invention also provides a powered vehicle, such as a scooter, comprising a drivable axle and drive means operable to drive the drivable axle, the drive means comprising a pancake motor.

The invention further provides an electric motor comprising a driven member and drive means operable to drive the driven member, the drive means comprising permanent magnets and electromagnets moveable relative to each other, and one being moveable with the driven member and the other being

fixed, there being means operable to energise the electromagnets in sequence to drive the permanent magnets relative to the electromagnets, thereby driving the drivable axle, and sensor means operable to sense the relative positions of the magnets and to control the energisation of the electromagnets in accordance with the speed and/or torque required.

The sensor means may control the time of energisation of the electromagnets. The electromagnets may be energised in pulses and the frequency and/or magnitude and/or duty cycle of the pulse train may be controlled by the sensor means.

Preferably the permanent magnets are carried by the driven member to move therewith, the electromagnets being fixed. Preferably the driven member is driven to rotate about an axis. The permanent magnets are preferably arranged in a ring around the axis.

The invention provides a vehicle powered by an electric motor as aforesaid. Preferably the permanent magnets are carried by a driven axle to rotate therewith, the electromagnets being fixed relative to the vehicle.

The invention still further provides an electric vehicle comprising an electric motor, battery means which, in use, power the motor, a driven axle, and transmission means operable to drivingly connect the motor and the driven axle, and decoupling means operable to decouple the driven axle from drive and to allow the driven axle to rotate freely.

Preferably the decoupling means comprise a clutch arrangement, preferably automatic, such as a one way clutch, sprag clutch or the like. The decoupling means may be operable to disconnect drive current to the motor, thereby allowing the motor to turn freely.

The invention also provides an electronic control system for an electric vehicle, comprising controls operable in response to at least one input signal to

provide at least one output signal, the control means, in use, receiving at least one of the following input signals:

- a signal indicative of the position and/or speed of a movable component of an electric motor;

- a signal indicative of torque demand;

- a signal indicative of battery voltage and current;

- a signal indicative of maximum permitted torque values;

and providing at least one of the following output signals:

- a signal indicative of required characteristics for drive current for the motor;

- a signal indicative of energy consumption and/or energy remaining stored in the battery;

- a signal indicative of vehicle speed.

Preferably the system provides a signal indicative of the duration, frequency, amplitude and/or duty cycle of current pulses required to drive the electric motor.

The system may comprise a microprocessor and/or transistor based control circuits, preferably field effect transistors.

The invention further comprises an electric vehicle, such as a cycle or scooter, having any, all or any combination of the features set out above.

The invention will now be described in more detail by way of example

only and with reference to the accompanying drawings, in which:

Fig. 1 is a schematic perspective view of a scooter embodying the invention;

Figs. 2 and 3 are side and plan views of the chassis of the scooter in Fig. l;

Figs. 4A to D are partial schematic views of drive transmission arrangements for a pancake motor;

Figs. 5A and C are side elevations of a motor arrangement for the scooter of Fig. 1 and Fig. 5B is a horizontal section at B-B in Fig. 5 A;

Fig. 6 shows transmission arrangements of Figs. 4A to D in more detail and incorporating a decoupling clutch;

Fig. 7 is a side elevation, in section, of a decoupling clutch for the arrangement of Fig. 6;

Fig. 8 is a block diagram of a control system for use in the vehicle in Fig. 1; and

Fig. 9 illustrates a schematic design for a control member for controlling the system of Fig. 8.

Chassis

A chassis system has been developed such that the chassis not only forms the main structural component of the vehicle 10, to which all other components are directly or indirectly fastened, but also serves as the housing for the traction batteries 12 (Fig. 2). To produce a small electric motorcycle 10 having reasonable performance requires approximately sixty five kilograms of batteries occupying a volume of 0.04 cubic metres, equivalent mass and volume to thirty house bricks. Further, the batteries 12 should be distributed such that the centre of gravity of the vehicle is laterally centralised and optimised both longitudinally and with respect to height to provide well balanced driving characteristics with sufficient ground clearance. Existing electric scooters typically have batteries mounted in compartments in the bodywork and/or in the underseat position normally required for crash helmet storage which is far

from ideal in terms of weight distribution, centre of gravity requirements or safety.

The chassis 14 is typically constructed using two parallel, rectangular section steel tubes 16 formed into an open 'U\ converging at the front to meet the headstock 18 and extending to the rear of the vehicle 20. Battery housings are then provided by metal trays or enclosures which can also form cross members between the two longitudinal members. Battery housings can also be provided by fastening mountings to the sides, top or bottom of the chassis.

A main chassis 14 is therefore produced which not only houses the batteries 12 without protrusions into the body of the vehicle 10, but also encloses and secures them into a structure so as to reduce the risk of their coming loose in the event of an accident, for example. Since the batteries are then housed within the chassis structure itself, normal motorcycle storage facilities remain available, such as crash helmet storage in a lockable compartment beneath the seat.

Such a chassis could also be constructed using formed sheet metal members joined so as to form a chassis with integral battery trays or housings, or a sheet metal monocoque into which the batteries are placed so that the monocoque used forms the housing. Such integral chassis/housing assemblies could also be manufactured from plastic or composite materials, for example.

It can be seen that the vehicle 10 in Fig. 1 is a scooter having two wheels 22 and a step-through chassis allowing unimpeded movement of the user's legs through a space 24 between the seat 26 and the handlebars 28. Beneath this space 24, there is a footplate 30 on which the user may rest his feet. It is to be noted that some of the batteries 12 are located beneath the footplate 30.

The chassis 14 has been developed so that it can easily be adapted to accept standard suspension and body components to enable existing vehicles to be converted to electric drive as well as for the production of bespoke vehicle

designs.

Electric Motor

The electric drive motor used is typically a brushed DC 'pancake' configuration, i.e. of cylindrical shape with a diameter approximately twice its length of the type manufactured by The Lynch Motor Company. A pancake motor comprises a rotor of electrically insulatmg material in which radial sheets of conducting material are embedded. Permanent magnets are provided in stators to either side of the rotor. Current is fed to the radial sheets through a brush system, acting as a commutator, to provide the motive force. Its small physical size, high power to weight ratio (2kw/kg peak) and high efficiency (92%) make it suitable for electric vehicle traction where performance is to be optimised. The motor is of basic pancake construction but with the rotor having copper strip windings, typically 5mm wide and lmm thick, to reduce Ohmic losses. The copper strips are bent and folded to form the commutator with, typically, solder joints at the periphery where centrifugal air cooling has maximum effect. High energy magnets, typically Neodinium Boron Iron permanent magnets, are housed in the motor casing, as is the brush assembly.

Other types of motor can be used, but a reduction in motor efficiency has an adverse cumulative affect on other components. For example, if motor efficiency is reduced from ninety to eighty percent, current draw must mcrease by twelve percent to compensate. Increased current draw reduces the available battery capacity which, typically, would then reduce the range by sixteen percent. Resultant increased component heating would produce further losses such that a ten percent reduction in motor efficiency can produce a range reduction in excess of twenty percent.

This motor can be used to drive the vehicle either via a transmission system, directly coupled to the driven road wheel or built in as part of the driven road wheel. When used with an existing scooter transmission system it can be positioned typically on the side of the redundant crankcase or in place of

the crankcase, for example (Fig. 4). Directly replacing an internal combustion engine in an otherwise unmodified scooter minimises cost by maximising the number of existing components which can be used.

Fig. 4 shows a pancake motor 32 mounted in four positions on existing scooter transmission casing 34 with engine components removed and cylinder aperture 36 blanked off. In Fig. 4A, the motor 32 is mounted on the side of a redundant crankcase 38 to drive road wheel 40. In Fig. 4B, the motor 32 is mounted in place of crankcase 38. In Fig. 4C, the motor is mounted at the hub of the wheel 40 on a swinging arm. In Fig. 4D, the motor 32 is mounted inside the wheel hub.

A new direct drive motor system can also be used whereby the driven wheel or wheels typically form the rotor 50, or are fixed to the rotor, and the suspension component 52 housing the wheel forms the stator (Fig. 5). Such a motor system has magnets 54, typically high energy permanent magnets, typically embedded into the wheel hub 56 or as part of a rotor fixed to the wheel hub, and stationary windings 58 mounted, typically, in or on the wheel mounting 52 or housing or another stationary part of the vehicle. The rotational speed and angular position of the wheel 50 is sensed by a transducer, typically a magnetic or optical sensor, typically mounted at the hub 56. The wheel can have more than one rotor fixed to it to increase torque, or both wheels can be rotors or have rotors attached to produce a two wheel drive motorcycle. Speed and positional information are transmitted to a microprocessor controlled speed controller which pulses the current to the windings at a frequency and duty cycle appropriate to the actual speed and the required torque. An advantage of the system described above is the elimination of wearing or sliding components, such as brush or slip ring assemblies. Alternatively, the current can be controlled by a mechanical commutator, typically mounted on the rotor, which passes current to the windings via a brushed mechanism.

The advantage with electronic commutation is that, as the magnet passes

the winding, the exact point in the physical relationship between the winding and the magnet at which the current is applied can be automatically electronically adjusted to optimise motor power and efficiency, i.e. providing automatic motor timing. Typical dwell angle for coil current "on" is shown (59). As with the ignition timing on an internal combustion engine, commutation timing can be optimised to match a particular rotational speed, and torque demand as dictated by the electromc "throttle" position. Alternatively, commutation timing adjustment can be provided using a mechanical commutator by physically varying the relationship between the brushes and the commutator by mounting the brush assembly on a bearing and rotating it according to motor speed and torque demand typically by means of a counterweight assembly.

Transmission Svstem

The transmission system is a new combination of components configured so as to optimise efficiency. Tests have shown that vehicle efficiency in terms of distance travelled related to energy consumption can be increased if the vehicle is allowed to roll freely or 'coast' when slowing or descending hills. Not only is this due to the elimination of unwanted 'engine braking', but, in the case of battery powered vehicles, this allows the batteries increased recuperation time, i.e. off load time when the battery chemistry can regain its natural equilibrium. In urban conditions, where acceleration and stopping is frequent, this factor alone can increase available battery capacity, hence range, by over twenty percent.

Power is transmitted from the motor 60 to the driven wheel 62 by conventional means such as a chain, fan belt, toothed belt or gears 64 (Fig. 6). Rotational resistance within the transmission system for efficient 'coasting' is minimised by the decoupling of the system at a suitable point or points, allowing the remainder of the transmission system still engaged to rotate freely. Suitable decoupling can be provided by breaking the motor electrical circuit by means of a switch or solenoid thereby eliminating back EMF resistive braking

forces within the motor as it rotates off load. The system can also be decoupled by means of an automatic clutch system 66A,B,C,D, such as an electromagnetic clutch, or 'one way' clutch device, such as a 'sprag' clutch, placed in the system at a suitable point. Fig. 6 shows several possible positions along the drive chain for a decoupling clutch. At 66A, the decoupling clutch is at the motor output shaft. At 66B, the decoupling clutch is in driving gear or sprocket or pulley. The driveshaft 68 replaces crankshaft in standard scooter transmission. At 66 C, the decoupling clutch in in driven gear or sprocket or pulley. At 66D, the decoupling clutch is in wheel hub. Fig. 7 shows schematically a suitable one¬ way, or "sprag" clutch 70. With a simple single ratio chain, belt or gear type transmission, the clutch can be situated at the driven wheel, thus completely decoupling the road wheel from the transmission system when 'coasting'. As shaft 72 rotates clockwise rollers 74 lock in the converging housing, radial forces then locking the device into housing 76. As shaft 72 rotates counter¬ clockwise, the device frees, acting as a needle roller bearing. Alternatively the clutch can be situated at the driving sprocket, pulley or gear either directly decoupling this from the motor and drive shaft or decoupling the motor itself from the rest of the transmission system thereby allowing the entire transmission system to rotate freely during 'coasting'. If using a sprag clutch, the latter system also provides a quick and simple means of installing the motor with no fastening system required to connect the drive shaft as the sprag clutch can be this interface (Fig. 6). If the transmission system utilises a gearbox for ratio changes, the clutch or clutches could also be situated at any suitable point in the gear train.

This novel combination of 'pancake' motor, simple chain, belt or geared drive, and decoupling device provides an efficient and compact transmission package that is ideal both for use in bespoke designs or for conversion of existing motorcycle transmission systems whereby the internal combustion engine components are removed i.e. piston, cylinder, connecting rod and crankshaft. The crankshaft is replaced with a drive shaft and the electric motor is fastened to the side of the transmission casing thereby driving the transmission system through the existing crankcase (Fig. 6).

A significant advantage of an electric motor over conventional internal combustion engine drive is that no drive take-up device, such as a slipping plate clutch device or torque converter, is required between the motor and transmission system as the motor can start from rest producmg high torque at low speeds. This characteristic also reduces or eliminates the requirement for ratio changes in the transmission.

This transmission principle can also be applied to three and four wheeled vehicles where optimisation of transmission efficiency is important.

Electronic Control Svstem

The design of a multi-function electronic control system has been developed to manage all power handling aspects of the vehicle. It can control motor timing for the new type of motor described, and can provide all necessary driver information.

Typically, a single system of integral Field Effect Transistors (FETs) are used for the three functions of motor speed control, battery charging, and DC/DC conversion for obtaining direct current at lower voltages for lights and other ancillary equipment. Rationalisation of the system design so that the same FETs are used for these three power control functions, as opposed to the provision of three separate FET systems, increases efficiency in terms of size, weight and cost (Fig. 8).

A control system 80 comprising integral micro processor receives various inputs 82, and yields various outputs 84, as will now be described. First, the system receives positional and velocity information from a transducer housed in the motor, and torque demand information from, typically, an accelerator pedal or twist grip attached or combined with, typically, a potentiometer or other positional transducer, such as a proximity sensor. Such a transducer 86 can be an integral component of the accelerator pedal or twist grip assembly 87 (Fig.

9A), or can be a remote device operated typically via a sleeved cable, pushrod or similar device 88 (Fig. 9B).

The processor can then provide the FET system with precise instructions as to the duration and timing of the individual pulses of current to the motor windings for optimum efficiency.

The control system also monitors battery terminal voltage and current flow by means such as, typically, an electric 'shunt' device, and processes this information into the sum of energy input and energy output. This sum can be displayed on an instrument, typically a bar readout, LCD screen or needle gauge to provide driver information on energy consumption i.e. an electrical 'fuel gauge'.

Similarly, in monitoring motor speed information for motor timing, this can be processed on a similar display device to provide vehicle speed information to the driver, negating the need for a separate mechanical speedometer drive system.

Information on the rate of energy usage compared to time can also be displayed to the driver on a similar display device, as can approximate remaining range, to help make optimum use of the energy available.

The processor can be programmed so that various modes of driving style can be selected, typically either pre-deteπnined or driver selectable. Typically two or more modes can be selected providing various levels of torque response to manual accelerator input to provide, for example, a high torque availability 'sport' mode and a lower torque 'economy' mode. This would enable a driver to alter the performance of the vehicle depending upon the type of journey anticipated and would help the driver obtain maximum duration, if required.

Using the FET system in reverse provides an integral 'on-board' battery charger, powered by current drawn, typically, from a mains electrical supply.

The processor can be programmed to vary the rate of charge dependant upon battery condition factors, typically, battery temperature, terminal voltage, battery charge time and energy remaining when charging began. Recharges can be accomplished in shorter periods if the output of the charger matches the ideal charge characteristic required of the battery, as can be provided by this programmable system.

The scooter uses the latest generation lead acid batteries, constructed, typically, by means of lead deposits on glass strands with the hquid electrolyte being applied, but contained by, an absorbent matrix. This system produces an available power density of forty watt hours per kilogram. The system can tolerate an extensive initial period of high charge current which, if reduced by pre-programmed increments, as can be provided by the charging system described, can reduce the full recharge period from several hours to thirty minutes, or can provide a half charge in ten minutes, without significant detriment to the battery cycle life.

This charging system can be pre programmed to match any required battery charging characteristic or profile which will enable the next generation batteries to be used without modification, these batteries being likely to have and energy density of one hundred watt hours per kilograms

Other battery charging features of the control system are that regenerative braking can be optimised by motor timing variation, as the motor can therefore be used more efficient in a generator mode. Also, solar panels can be used for trickle charging, using the DC/DC conversion and battery monitoring system. Solar panels can be used with the scooter, typically built into the bodywork, or as a fold-away panel.

General

Whilst the increased efficiency gained by using any one of the above components in isolation may be marginal, e.g. the motor is only 10% more

efficient than other motors known to be currently used in electric scooters, the effect of compounding efficiencies (or inefficiencies) in a system with several components is significant. For example, four components used together and having an individual efficiency of 80% have an overall efficiency of only 40% whereas an individual efficiency of 90% would produce an overall efficiency of 65%, i.e. a 65% increase in efficiency. Also, as described above, reduced efficiency in one component results in further inefficiencies and losses in other components, particularly batteries such that an overall reduction in efficiency of 20% can result in a 40% reduction in range.

The above document refers to axles, particularly "driven axles". It is to be understood that other mechanical equivalents are to be encompassed by this term, whether or not rotatable members are mounted by means of an axle or otherwise.

The items described can be used individually, but maximum advantage is gained by their combination into an integral package.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance, it should be understood that the Apphcant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.