Title of Invention

A SINGLE MACHINE SYSTEM PERFORMING AS A STARTER MOTOR AND ALSO AS A GENERATOR FOR AN AUTOMOBILE

Abstract

A single machine system performing as a starter motor and also as a generator for an automobile comprising an electronic controller; an ignition module, incorporating a 'CDI unit, connected to the electronic controller on its output side; an accelerator limit switch connected to electronic controller on its input side and being actuated by the operation of accelerator; the said controller, on detecting the actuation of the accelerator limit switch with ignition switch on and the engine speed below a pre- determined value, shifting the system to motor mode, to start the engine; and on detecting the engine speed equal to or above the pre-determined value, shifting the system to generator mode; a battery; an electronic switch module performing the tasks of inverter and rectifier; a voltage regulator; the battery supplying power, through the switch module, to the said machine in motor mode, the said machine, however in generator mode, after rectification of its output voltage by the switch module, charging the battery and supplying the electrical load of the vehicle; the battery terminal voltage being regulated in generator mode by the said voltage regulator.; a position sensor for sensing the angular position of the rotor of the machine, the said sensor being connected to the electronic controller on its input side, the said controller on detecting the engine speed to be either zero or idling, over a continuous predetermined interval of time as sensed by the sensor, switching off the CDI unit, to shut off the engine.

Full Text

This invention relates to a single machine system performing as a starter motor and also as a generator for an automobile herein after referred to as starter-generator system. More particularly though not exclusively, this invention is applicable to two-wheeler and three-wheeler automobiles. The proposed system has a poly phase machine connected to DC source through power electronic module which works as inverter and also as converter, electronic controller, position sensor module for rotor of the machine to sense the angular position of rotor, accelerator switch to realize various operations of the system. While separate starter motor and magneto are presently used in two wheelers and three wheelers to realize the functions of starting the engine and developing electrical power to meet the demands of the vehicle, the following disadvantages are observed with starter motor. • The starting system requires engagement of gears in starter motor and crankshaft of engine resulting in gear noise and inadvertent engagement of starter pinion with ring gear under engine running condition would lead to reliability issues of starter and ring gear. • Overrunning clutch is essential in the present system to ensure that the motor armature does not run at very high speed in case the starter switch remains in on condition after engine is fired. • Auto stop-start at traffic signals would be difficult to be implemented due to stringent life requirements for the existing starter motor Whereas the proposed system offers the following benefits • A single electrical machine performs the tasks of starter motor and generator thus reducing the parts count • The machine could be fitted in the same location as the existing magneto thus simplifying fitment requirements • Higher cranking speed could be realized to ensure positive firing • The rotor of the machine is coupled to crankshaft directly resulting in significant reduction of cranking noise and power loss which occurs in the existing starter system due to gear transmission. • High amount of electrical power could be generated to enable introduction future power demanding loads • Regenerative braking could be realized • Active damping by providing motoring torque at low speeds to engine shaft at appropriate instants of time could be realized to minimize engine vibration • Torque boost could be provided until a specified speed to improve the acceleration characteristics of vehicle • Auto stop-start at traffic signal conditions could be realized implying reduction of fuel consumption and emission. The other features of the invention would be apparent to those skilled in the art from the following further description. The system according to the invention consists of • a poly phase machine with electromagnet field or permanent magnet field developed by rotor and rotor position sensor realized with hall sensor or any other appropriate sensor • a poly phase inverter bridge made of appropriate electronic switches such as MOSFET or IGBT • Electronic control unit employing microcontroller or DSP or any other suitable programmable device to control the operation of the system. The single machine system performing as a starter motor and also as a generator for an automobile according to this invention comprises an electronic controller; an ignition module, incorporating a CDI unit connected to the electronic controller on its output side; an accelerator limit switch connected to the electronic controller on its input side and being actuated by the operation of the accelerator; the said controller, on detecting the actuation of the accelerator limit switch with ignition switch ON and the engine speed below a predetermined value shifting the system to motor mode, to start the engine; and on detecting the engine speed equal to or above the predetermined value, shifting the system to generator mode; a battery; an electronic switch module performing the tasks of inverter and rectifier; a voltage regulator; the battery supplying power, through the switch module, to the said machine in motor mode, the said machine, however in generator mode, after rectification of its output voltage by the switch module, charging the battery and supplying the electrical load of the vehicle; the battery terminal voltage being regulated in generator mode by the voltage regulator; a position sensor for sensing the angular position of the rotor of the machine, the said sensor being connected to the electronic controller on its input side, the said controller on detecting the engine speed to be either zero or idling, over a continuous predetermined interval of time, as sensed by the sensor or the accelerator limit switch, switching off the CDI unit, to shut off the engine. The invention will now be described by reference to the accompanying drawings which illustrate, by the way of example and not by way of limitation, in Fig.l The Circuitry of the starter-generator system Fig.2 Configurations of poly phase machine connected to DC source through electronic switch module (PM type and wound field type) Fig.3.0 Schematic of electronic switch module for three phase system using MOSFET Fig.4.0 Signals obtained from hall sensor module for three-phase starter-generator system Fig.5.0 Circuitry of voltage regulator The system consists of electrical machine which could be operated as motor or generator, electronic switch module to enable transfer of power between battery and stator (armature) windings of machine in motor or generator modes, voltage regulator to regulate the terminal voltage of the battery in generator mode, rotor position sensing unit to generate switching signals to control electronic switch module, accelerator limit switch to realize auto stop-start operation, excitor transformer to charge the capacitor in CDI(capacitor discharge ignition) unit Referring to Fig 2.0, the poly phase machine could use • either a permanent magnet field or electromagnet field whose windings are connected through slip ring to DC source for field excitation • Appropriate poly-phase stator winding in stator (i.e. armature) Fig. 2.0 shows configuration of a permanent magnet brushless DC machine as well as a wound field machine with three phases applicable for this invention. Various other ways of realizing poly phase system would be known to the expert in the art. The rotor of the machine is preferably coupled to engine shaft similar to magneto. The electronic controller indicated in Fig. 1.0 employs a microprocessor or DSP or microcontroller or any other programmable device to realize various logic and control functions required for the system operation. Fig. 3.0 shows the circuitry of electronic switch module which could be realized with devices such as MOSFETs or IGBTs. The rotor position sensor module consists of hall sensors displaced at equal angular interval with a specific relation to stator winding axis. The signals obtained from rotor position sensor module employing three hall sensors for three-phase machine are given in Fig.4.0. These signals are given to micro controller or any appropriate programmable device which in turn provides switching pulses for the electronic switch module generated by electronic controller based on the hall sensor signals. The circuitry of voltage regulator to maintain the battery voltage at a specified value in generator mode of operation is provided in Fig. 5.0. As indicated in Fig. 5.0, voltage regulator could be realized with MOSFET based circuit or with thyristor based circuit. The overall operation of the system is explained as follows. After turning on ignition switch of vehicle, the controller is enabled. The accelerator limit switch changes its state if the accelerator handle of the two-wheeler is rotated by a small extent. If the engine speed is below a pre specified value (including zero) and accelerator limit switch is turned on due to rotation of accelerator handle, the controller takes the system to motor mode. In motor mode, battery power is fed to the machine through electronic switch module operating the • machine as a DC motor. Once the engine speed is above a specified value indicative of engine firing, the controller takes the system to generator mode. Battery terminal voltage is regulated at a fixed value either using a MOSFET/IGBT based circuit or thyristor based circuit. It may be noted that the anti-parallel diodes of MOSFETs in electronic switch module are used for rectification of alternating voltage developed by armature windings of stator. For auto stop operation, a wheel speed sensor could be used to indicate zero speed of the vehicle or idling status of engine could be sensed as indicated by accelerator limit switch to stop the vehicle. Thus engine could be automatically shut down if zero speed of the vehicle is detected by the controller continuously for a pre specified duration or if the engine idles for a pre specified duration as indicated by accelerator limit switch. Turning off the engine is realized through a control signal from electronic controller issued to CDI unit. The exciter transformer shown in Fig. 1.0 is used to charge the CDI capacitor for ignition purpose. This transformer is basically a step up transformer whose primary is connected across one set of line terminals stator windings and secondary winding is connected to CDI module. Alternatively, a excitor winding could be provided inside the stator itself as in the case of existing magneto and connected to CDI unit directly. This invention leads to the following benefits • Two separate electrical machines namely starter motor and magneto are combined as a single electrical machine leading to a significant reduction of wear and tear parts resulting in increased reliability. • Higher cranking speeds could be realized compared separate starter motors leading to positive firing of engine. • Higher motor and generator efficiency is realized leading to fuel economy • Enables introduction of stop-start system to realize fuel economy and emission reduction benefits • Availability of Large electrical power allows power demanding loads such as electrically operated valves towards various benefits • The machine could be fitted in the place of existing magneto and hence the modifications required in the engine design to accommodate the system are minimal • The system could be retrofitted in vehicles already on road The terms and expressions herein are of description and not of limitation We claim 1. A single machine system performing as a starter motor and also as a generator for an automobile comprising an electronic controller; an ignition module, incorporating a CDI unit, connected to the electronic controller on its output side; an accelerator limit switch connected to electronic controller on its input side and being actuated by the operation of accelerator; the said controller, on detecting the actuation of the accelerator limit switch with ignition switch on and the engine speed below a predetermined value, shifting the system to motor mode, to start the engine; and on detecting the engine speed equal to or above the pre-determined value, shifting the system to generator mode; a battery; an electronic switch module performing the tasks of inverter and rectifier; a voltage regulator; the battery supplying power, through the switch module, to the said machine in motor mode, the said machine, however in generator mode, after rectification of its output voltage by the switch module, charging the battery and supplying the electrical load of the vehicle; the battery terminal voltage being regulated in generator mode by the said voltage regulator; a position sensor for sensing the angular position of the rotor of the machine, the said sensor being connected to the electronic controller on its input side, the said controller on detecting the engine speed to be either zero or idling, over a continuous predetermined interval of time as sensed by the sensor, switching off the CDI unit, to shut off the engine. , A single machine system as claimed in claim 1 wherein the said machine with polyphase stator windings is operable as motor or generator. 3. A single machine system as claimed in claim 1 and claim 2 wherein the machine has a rotor developing magnetic field when current is passed through rotor winding. 4. A single machine system as claimed in claim 1 and claim 2 wherein the machine has a rotor with permanent magnet to develop magnetic field as an alternative to claim 3. 5. A single machine system as claimed in any one of the preceding claims wherein the inverter circuit comprises an inverter bridge of electronic switches such as MOSFET or IGBT. 6. A single machine system as claimed in any one of the preceding claims wherein the electronic controller incorporates a microcontroller, microprocessor, DSP or other programmable ASIC. 7. A single machine system as claimed in any one of the preceding claims wherein the rotor is coupled to the crankshaft of the engine preferably. 8. A single machine system as claimed in any one of the preceding claims wherein an excitor transformer is provided for charging the capacitor in CDI unit for ignition purpose 9. A single machine system performing as a starter motor and also as a generator for an automobile substantially as herein described with reference to and as illustrated in the accompanying drawings

Documents:

509-mas-2002-abstract.pdf

509-mas-2002-claims duplicate.pdf

509-mas-2002-claims original.pdf

509-mas-2002-correspondance others.pdf

509-mas-2002-correspondance po.pdf

509-mas-2002-description complete duplicate.pdf

509-mas-2002-description complete original.pdf

509-mas-2002-drawings.pdf

509-mas-2002-form 1.pdf

509-mas-2002-form 19.pdf

509-mas-2002-form 26.pdf