Hybrid Three Wheeler

Field of the Invention:

The present invention relates to a "Hybrid three wheeler", wherein an electric motor assists an internal combustion engine for driving the wheels of the vehicle in order to reduce fuel consumption and to enhance performance.

Background of the Invention:

A "Parallel Hybrid Vehicle" comprises an internal combustion engine and at least one electric motor which can independently provide driving power for the vehicle and can also act simultaneously in meeting peak power demands leading to reduced fuel consumption for the engine.

Parallel Hybrid vehicles wherein an electric motor assists an internal combustion engine for delivering additional power during rapid acceleration in order to reduce peak load on the engine are called "Mild Hybrid Vehicles". For example, Honda Civic is a Mild Hybrid Four Wheeler available in the market in which an electric motor is coupled to a crankshaft of the internal combustion engine. Starting of the engine and cruising at low speeds are performed by the electric motor alone. Gentle acceleration and high speed cruising is powered by the internal combustion engine and during rapid acceleration, the electric motor and the engine work together to provide powerful acceleration while limiting fuel consumption. During deceleration, the combustion process is inhibited and the motor functions as a generator for charging the vehicle battery.

US Patent 4148192 (Internal Combustion Electric Power Hybrid Power Plant) discloses a hybrid power plant wherein a direct current electric motor is coupled to a crankshaft of the internal combustion engine and a clutch mechanism is provided to selectively engage and disengage a drive shaft with the internal combustion engine and the electric motor. A storage battery is electrically connected to the motor generator to supply and receive electric current. The patent also discloses an arrangement of thermo electric semiconductors for using the waste heat from the internal combustion engine.

Peugeot had previewed a hybrid three - wheeled vehicle called "Hybrid3 Evolution" in which a supercharged internal combustion engine drives a rear wheel of the vehicle and two electric motors drive two front wheels for achieving reduced fuel consumption and enhanced performance. But such vehicles are highly expensive and therefore cannot replace the commonly used three wheelers - "auto rickshaws".

A low cost hybrid three wheeler that does not require major modifications of an auto rickshaw and that comprises an electric motor and an internal combustion engine coupled in a manner that occupies less space and is easy to assemble and service is much sought for.

Summary of the Invention:

The principal object of this invention is to provide a low cost hybrid three - wheeled vehicle comprising an internal combustion engine and an electric motor for reducing the fuel consumption and for improving driving performance of the vehicle. Another object of this invention is to provide a control system for suitably controlling the electric motor in order to operate the engine in its high efficiency region. Another object of this invention is to provide a mounting arrangement for the electric motor that occupies less space and offers flexible connection with a crankshaft of the engine in order to take care of misalignments during manufacturing and assembly of the individual parts. Another object of this invention is to provide a means of securing an electric power source of the vehicle so as to avoid accidental short circuit during assembly and while driving and to reduce the effect of vehicle vibrations on the electric power source. Another object of this invention is to provide a Start - Stop system for the vehicle that prevents unnecessary running of the engine and thereby improve the fuel efficiency further. It is a further object of this invention to provide a low cost hybrid three - wheeled vehicle that is easy to assemble, service and is easy to maintain.

According to the invention an electric motor is flexibly coupled to a flywheel of the internal combustion engine by means of an adjustable link arrangement with a cradle of the vehicle chassis. A motor controller receives input from an electronic control unit based on the vehicle load for controlling the electric motor in order to reduce fuel consumption and enhance driving performance considerably. An electric power source comprising a battery pack is mounted underneath the passenger seat at the rear side of the vehicle by means of removably connected brackets. The electronic control unit also controls ignition and performs engine starter control in order to prevent running of the engine at idling conditions.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Brief Description of Drawings:

Fig 1 is a pictorial view of the hybrid three wheeler chassis.

Fig 2 is a pictorial view of the internal combustion engine along with the electric motor for assisting the engine.

Fig 3 is a pictorial view showing the mounting arrangement of the electric motor with a flywheel assembly of the engine.

Fig 4 is a pictorial side view of the link arrangement for adjusting the position of the electric motor.

Detail Description of the Drawings:

Referring to Fig 1, a hybrid three wheeler comprises a chassis (10) made up of hollow rectangular cross members with which various parts are connected. Two long cross members, long cross member LH (11) and long cross member RH (12) are located on the two sides of the vehicle axis along the direction of travel. Two engine mounting cradles, engine mounting cradle front and engine mounting cradle rear (14) are connected with the two long cross members for mounting an internal combustion engine. There is a cross tube (15) that is welded to the two long cross members at right angles for supporting rear trailing arms (LH and RH). A central long member is connected with the cross tube and along with the two long cross members, it supports a floor board (17). A rear seat frame is connected with the two long cross members for mounting a passenger seat. A rear cabin upper cross member (19) is connected with the two long members for supporting a rear cabin. There is a front cowl (20) connected with the floor board. The front cowl supports a windshield. There is a B—pillar connected with the long cross members for supporting a partition wall (22). The partition wall separates the passenger seating area from the driver seating area. A soft top connecting tube (23) is fitted to the B-pillar for connecting a soft top cover between the rear cabin and the windshield. A driver seat frame is located in front of the partition wall for mounting a driver seat. Additional connecting tubes are fitted with the cabin for supporting the soft top cover. Two rear wheels are connected to each trailing arm LH and RH. Each trailing arm has a pivot point and a suspension support with the corresponding long cross member. A front wheel is connected with a front trailing arm which in turn has a pivot joint with a steering column. There is a front suspension support between the trailing arm and the steering column. A handle bar is connected with the steering column for changing the direction of travel of the vehicle. There is a dashboard connected with the front cowl and comprising the various switches and indicators for helping the driver in starting and driving the vehicle in traffic conditions.

Referring to Fig 2, a single cylinder, 4 Stroke, spark ignition internal combustion engine (30) is mounted on the engine mounting cradles. A crankshaft of the engine is connected with a flywheel assembly on its LH side. The flywheel assembly has permanent magnets along its internal periphery forming the rotor (32) of an alternator. A stator concentric with the rotor and separated from the rotor magnets by an air gap and having poles equal to that of the rotor poles is connected with an engine crankcase (34). Coils are wound around the stator poles for generating alternating current during the rotation of the crankshaft. The stator with coils along with the rotor forms an alternator. The engine includes a manual transmission with multi plate wet clutch for selectively engaging and disengaging the crankshaft with a drive shaft of the engine. The drive shaft in turn is connected with a differential for driving two wheel axles, LH and RH wheel axles through muff cups (36). A starter motor (37) is mounted on the engine crankcase (34) having a pinion for engaging with a starter gear of the flywheel assembly.

The inlet manifold of the internal combustion engine is connected to the output of a carburetor which is used for varying the air - fuel mixture. A fuel tank is mounted underneath the cabin and provides fuel to the carburetor for running the internal combustion engine.

Referring to Fig 3 and Fig 4, a flywheel shaft is directly connected with the flywheel assembly of the engine. A rotex coupling (40) having two halves are used for flexibly coupling a motor shaft to the flywheel shaft. A star shaped elastomer spider is present between the two coupling halves for damping torsional vibrations and for compensating shaft misalignments. The flywheel shaft has a taper for mating with the flywheel side coupler. The motor shaft has a keyway for mating with the motor side coupler. An external ball bearing is located around the motor shaft to compensate for the longitudinal load on the motor shaft. The flywheel is also connected with a fan (42) for providing air cooling for the engine during rotation of the crankshaft.

A hollow rectangular welded member (50) is welded perpendicularly to the rear engine mounting cradle (14). Two joints of a link arrangement (52) are connected to a long edge (54) of the welded member (50) such that the tightening of a bolt (55) will move a pivot point (56) of the link arrangement (52) towards the welded member (50) in a circular fashion. A third joint (57) of the link arrangement is connected with a sliding member (58) that can slide along the long edge (54) of the welded member (50). The . long edge (54) of the welded member (50) has holes at frequent heights and can be fastened with the sliding member (58) to arrest the sliding motion of the sliding member (58). When the pivot point (56) of the link arrangement (52) moves toward the welded member (50), the sliding member (58) slides up, along the welded member (50). The height of the sliding member (58) can thus be adjusted. The sliding member (58) is fastened to a motor mounting L - plate (59). Both the L - plate (59) and the sliding member (58) have elongated mounting holes for adjusting the position of the L - plate (59) along two perpendicular axes which are each perpendicular to the axis along the height of the sliding member (58). The motor mounting L - plate (59) has a mounting hole for fitting the electric motor (60) such that the motor shaft will face the flywheel shaft. Thus the motor shaft position with respect to the flywheel shaft can be adjusted along three axes. This adjustment means helps in compensating for misalignments of motor shaft and flywheel shaft during manufacturing and assembly. The motor position can be adjusted accurately so that the motor shaft and the flywheel shaft lie on the same axis.

A Lynch motor which is a highly efficient permanent magnet DC motor with an axial air gap is used as the electric motor (60) in the preferred embodiment. The electric motor (60) has an electrical connection with an electric motor controller (61) that is mounted on a controller mounting plate which is in turn welded to the long cross member LH (11). The controller (61) receives power supply input from a battery pack that is located under the rear seat frame. The controller also receives a control input from an Electronic Control Unit (ECU) that is mounted under the rear cabin.

The battery pack is made up of four 12V Lead Acid Batteries connected in series, thus forming a 48V DC power source. Brackets are removably connected across the seat frame after assembling the batteries in order to hold the batteries in its place during vehicle vibrations. Additionally another 12V battery is located along side the 48V battery pack for supplying to DC loads like Starter Motor (37), DC horn and indication bulbs.

Whenever a throttle pipe rotatably fitted with the handle bar RH is rotated by the driver, the electrical output of a throttle potentiometer varies due to a throttle cable that is connected between the throttle pipe and the throttle potentiometer. The throttle cable is also connected to the carburetor for varying the air - fuel mixture in order to control the power delivered by the internal combustion engine (30).

The ECU also controls ignition of the internal combustion engine by receiving input from at least an engine speed sensor and a throttle position sensor. The throttle potentiometer functions as a throttle position sensor. A pulser coil which is fixedly mounted to the engine crankcase (34) and is separated from a rectangular metal strip located along the outer periphery of the flywheel assembly by a small air gap provides the engine speed signal corresponding to the rotation of the crankshaft. Based on the input received from the pulser coil and the throttle potentiometer, the ECU provides a signal to an ignition coil for generating high voltage across a spark gap of a spark plug (65) mounted on the engine cylinder block (66). The high voltage generated produces a spark for igniting the air - fuel mixture.

Based on the throttle position signal received from the throttle potentiometer and the engine speed signal from the pulser coil, the ECU provides appropriate electric signal to the electric motor controller (61) so that the DC voltage input to the electric motor (60) that determines the torque produced by the motor (60) can by varied based on the engine load. For example, during light loads like when cruising at low speeds, the output from the throttle potentiometer is low. The ECU thus provides a low signal to the electric motor controller which in turn provides little or no input to the electric motor (60). The electric motor thus will not assist the engine (30) at such light loads. But during rapid acceleration request from the driver in the form of increased throttle position, the ECU provides high output signal to the electric motor controller (61) which in turn provides high supply input to the electric motor (60). The electric motor (60) will generate high torque required for meeting the peak load and hence reduces the peak load demand on the engine. In addition to the speed sensor signal and throttle position signal, the ECU also receives signal from a power assist switch which enables the power assist function of motor assisting the engine during peak load demands. The power assist switch helps the driver to override the hybrid function of the vehicle and operate the vehicle on engine power alone. For cruising at high speeds, the ECU provides signal to the electric motor controller such that both the engine and the motor share the load and thereby limit fuel consumption.

For the Power assist function the ECU also checks the voltage of the battery pack. If the voltage is less than 44V, then the output signal to the electric motor controller (61) will be zero. This is to prevent draining of the battery pack and thereby extend the battery life.
For the Power assist function, the ECU also calculates engine acceleration from the speed signal received from the pulser coil and the rate of change of throttle position from the throttle potentiometer output signal. If the engine acceleration is beyond a predetermined value and if the rate of change of throttle position is beyond a predetermined value in accelerating direction and if the transmission is not in neutral, then the output of the ECU to the electric motor controller will be 100% for 2 seconds. This is to assist the engine during sudden, high acceleration without increasing the fuel consumption.

For the Power assist function, if the ECU senses that the rate of change of throttle position is beyond a predetermined value in decelerating direction for 2 seconds and if the engine speed is equal to idling speed, then the ECU output to the electric motor controller will be zero so that the electric motor will not provide any additional torque to the engine. This is to improve the response of the vehicle during sudden deceleration request from the driver by sudden rotation of the throttle pipe in decelerating direction.

The ECU also includes a Start - Stop function which inhibits ignition when predetermined idling stop conditions are satisfied. The idling stop conditions include the throttle position to be less than a predetermined value, the vehicle speed to be zero and brake is applied continuously for a predetermined duration. There is also a Start - Stop enable button on the dashboard of the vehicle which the driver can switch ON/OFF to enable or disable the Start - Stop function. If the Start - Stop enable button is in OFF condition, then the ECU will not inhibit ignition even if the idling stop conditions are satisfied.

For the Start - Stop function, when the vehicle is in idling stop state i.e. ignition is inhibited and ignition switch is ON, if the brake is released and if the throttle potentiometer output voltage exceeds a predetermined value and if the transmission is in neutral condition or if clutch is disengaged, then a starter relay is energized and ignition is enabled. The starter relay is an electromechanical relay that connects the 12V vehicle battery to the Starter Motor (37) when energized. Thus the Starter Motor (37) is activated and the pinion of the Starter Motor (37) will mesh with the starter gear of the flywheel assembly and rotate the flywheel assembly along with the crankshaft. The engine (30) will start and the driver can shift gear and drive the vehicle.

For the Start - Stop function, the ECU receives input from a brake switch, a gear position switch, a clutch switch and a temperature sensor placed on the Starter Motor (37). During idling stop condition, if the temperature sensor signal to the ECU indicates that the Starter Motor surface temperature is beyond a predetermined value, then ignition inhibition will not be performed even if the idling stop conditions are satisfied.

This protects the Starter motor (37) from failing due to overheating during repeated start - stop conditions like when the vehicle moves in dense traffic conditions.

For the Start - Stop function, the ECU also senses the battery voltage from the supply input it receives from the 12V battery and if the battery voltage sensed is less than 11.5V, then the Starter Motor (37) activation is not performed even if the restarting conditions are satisfied. This is to prevent unnecessary draining of the 12V battery in order to extend its life.

The ECU also has additional Starter Motor (37) protection function that prevents continuous cranking of the engine for more than 5 seconds. After 5 seconds, the Starter Relay supply will be deactivated so that the Starter Relay will not receive any supply input. The ECU provides a 5 second rest period and allows Starter Relay energization only after the rest time. Thus continuous operation of the Starter Motor is prevented which will enhance the life of the Starter Motor. Such conditions arise during starting of the engine at cold conditions and attempts to start without fuel or ignition.

For the Start - Stop function, there is also provided a reset LED on the dashboard of the vehicle which will glow if three attempts to restart the vehicle from idle stop state are failed. This prompts the driver to switch OFF ignition switch and switch ON again to reset the system. There is also provided an Electric Start (ES) switch on the dashboard for activating the starter relay if vehicle transmission is in neutral condition irrespective of the status of the Start - Stop system. Thus the driver can also use the ES switch to start the engine when an ignition switch is turned ON and the vehicle transmission is in neutral.

The electric motor controller (61) can also be configured to enable regeneration so that the battery pack will be charged during deceleration.

Since the electric motor (60) is coupled to the crankshaft of the engine (30), the engine (30) occupies less space and no modification is required in the transmission gear train and crankcase (34). A 48V battery pack, an electric motor (60), electric motor controller (61) and their associated assembly are the only major additional parts when compared to a conventional "auto rickshaw". Hence the low cost of the vehicle. The parts are easily accessible and therefore easy to assemble and service.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the claims.

We Claim:

1. A hybrid three wheeler comprising:

a hollow rectangular welded member, welded to rear engine mounting cradle;

a sliding member slides up along the hollow rectangular welded member;

a L shaped plate for motor mounting fixed perpendicular to the sliding member.

2. The hybrid three wheeler as claimed in claim 1, wherein the said hollow rectangular welded member is welded preferably perpendicularly to the rear engine mounting cradle.

3. The hybrid three wheeler as claimed in claim 1, wherein the said hollow rectangular welded member is provided with holes at varying heights thereby height of sliding member can be adjusted.

4. The hybrid three wheeler as claimed in claim 1, wherein the said sliding member is perpendicular to the hollow rectangular welded member.

5. The hybrid three wheeler as claimed in claim 1, wherein the said sliding member is fixed to the hollow rectangular welded member with two joints of link arrangement.

6. The hybrid three wheeler as claimed in claim 1, wherein the said sliding member is fastened to the motor mounting L plate and is provided with a recess to project the motor shaft out.

7. The hybrid three wheeler as claimed in claim 1, wherein the said L plate is provided with mounting hole for fitting electric motor such that the motor shaft will face the flywheel shaft.