Claims:WE CLAIM:
1. A system (100) for starting a vehicle (10) comprising:
a rotary electric machine (44);
a gearbox (46) having a plurality of gears arranged to form a desired gear train to achieve a required gear ratio to start the vehicle (10), the gearbox (46) coupled with the rotary electric machine (44) and a crankshaft (48) of the vehicle (10) to transmit power from the rotary electric machine (44) to the crankshaft (48);
a control unit (102) configured to generate an output signal indicative of the required gear ratio based on one or more predetermined vehicle load parameters; and
an actuator (104) in communication with the control unit (102), wherein the actuator (104) is configured to receive the output signal from the control unit (102) and align the gears to obtain the required gear ratio for starting the vehicle (10).

2. The system (100) as claimed in claim 1, wherein the control unit (102) is configured to determine the required gear ratio based on the one or more predetermined vehicle load parameters to start the vehicle (10).

3. The system (100) as claimed in claim 2, wherein the control unit (102) comprises:
a detection unit (108) configured for detecting ON conditions of an ignition key (50) and an electric start switch (52); and
a determination unit (110) configured for determining the gear ratio based on the one or more predetermined vehicle load parameters.

4. The system (100) as claimed in claim 1, wherein the one or more predetermined vehicle load parameters comprises an engine temperature, a throttle position and an engine load.

5. The system (100) as claimed in claim 4, wherein the control unit (102) is configured to:
generate a high gear ratio output signal when the measured engine temperature is high and engine load is low; and
generate a low gear ratio output signal when measured engine temperature is less and engine load is high.

6. The system (100) as claimed in claim 1, wherein the control unit (102) is configured to determine battery voltage of a battery (54) of the vehicle (10) and generate the output signal if the battery voltage is greater than a reference value.

7. The system (100) as claimed in claim 1, wherein the control unit (102) comprises a fuel injection control unit (FI-ECU) or a vehicle control unit or a starter control unit.

8. The system (100) as claimed in claim 1, wherein the rotary electric machine (44) comprises a starter motor.

9. The system (100) as claimed in claim 1, wherein the gearbox (46) comprises plurality of fixed gear ratio configuration, the plurality of fixed gear ratio configuration comprises a first predetermined gear ratio corresponding to a low engine temperature and a high engine load.

10. The system (100) as claimed in claim 9, wherein the plurality of fixed gear ratio configuration comprises a second predetermined gear ratio corresponding to a high engine temperature and a low engine load.

11. The system (100) as claimed in claim 9 or 10, wherein the first predetermined gear ratio is lesser than the second predetermined gear ratio.

12. The system (100) as claimed in claim 9 or 10, wherein the plurality of fixed gear ratio includes the first predetermined gear ratio for a first predetermined condition, the second predetermined gear ratio for a second predetermined condition and an Nth predetermined gear ratio for a Nth predetermined condition, where the number of gear ratios is fixed, and the control unit is configured to provide signal indicative of the ratios between the fixed gear ratios.

13. The system (100) as claimed in any one of the preceding claims, wherein the at least one or more predetermined vehicle load parameters is measured by sensors (56) disposed on the vehicle (10).

14. A method (300) for starting a vehicle (10), the vehicle (10) having a rotary electric machine (44) coupled with a crankshaft (48) through a gearbox (46) having plurality of gears arranged to form a desired gear train to achieve a required gear ratio to start the vehicle (10), a control unit (102) and an actuator (104) in communication with the control unit (102), the method (300) comprising the steps of:
measuring (302) at least one or more predetermined vehicle load parameters by sensors (56) disposed on the vehicle (10);
determining (304) a required gear ratio based on the measured one or more predetermined vehicle load parameters by the control unit (102);
generating (306) an output signal indicative of the required gear ratio and transmitting the output signal to the actuator (104) by the control unit (102); and
receiving (308) the output signal and aligning the gears by the actuator (104) to obtain the required gear ratio for the electric machine (44) to start the vehicle (10).

15. The method (300) as claimed in claim 14 comprising the step of detecting ON conditions of an ignition key (50) and an electric start switch (52) by a detection unit (108) of the control unit (102).

16. The method (300) as claimed in claim 14, wherein the one or more predetermined vehicle load parameters includes an engine temperature, a throttle position and an engine load.

17. The method (300) as claimed in claim 16 comprising the steps of:
generating (400) a high gear ratio output signal by the control unit (102) when the measured engine temperature is high and engine load is low; and
generating (402) a low gear ratio output signal by the control unit (102) when measured engine temperature is less and engine load is high.

18. The method (300) as claimed in claim 15 comprising the steps of:
determining (500) battery voltage of a battery (54) of the vehicle (10) by the control unit (102);
generating (502) the output signal by the control unit (102) for the actuator (104) when the battery voltage is greater than a reference value; and
communicating the output signal indicative of the required high or low gear ratio to the actuator (104).
, Description:FIELD OF THE INVENTION
[001] The present invention generally relates to a system for starting a vehicle and a method thereof. More particularly, the present invention relates to the system for starting the vehicle with variable gear ratio for cranking based on an input of engine load.

BACKGROUND OF THE INVENTION
[002] In an existing two-wheeler vehicle configuration, a crankshaft has to be rotated at a certain speed for starting an engine of the vehicle. Conventionally, the vehicles have been included with a kick-starting system for starting the vehicle. However, the kick-start system involves more manual effort and often results in a rider fatigue. In order to overcome this limitation, a starter motor was used for cranking the engine. The starter motor typically produces an output having a high speed and a low torque. Gears were used for multiplying the low torque output from the starter motor to the high torque output at the crankshaft. During cranking of the engine, speed and torque requirements on the starter motor may vary with respect to one or more parameters including, but not limited to, an engine temperature, a friction, a compression load, a compression ratio, etc. However, in few conditions such as cold weather condition, a high torque and a low speed may be required, and in hot weather condition a less torque and high speed may be required to crank the engine efficiently. In existing starting mechanism designs, a fixed gear ratio is available, and it does not change with respect to the engine load conditions. That is to say, the gear ratio for a starter is set either with a low gear ratio or high gear ratio.
[003] One of the disadvantages of a fixed gear ratio starter system is that irrespective of engine load conditions, it always works at the same operating point, making the cranking process less efficient since more energy is consumed from the battery. This leads to draining the battery at a faster rate. Further, the vehicle start-ability is reduced due to reduction in battery voltage.
[004] Attempts have been made to address the aforesaid limitations. One attempt has been proposed by providing a planetary gear system. The planetary gear system requires two inputs to get a desired gear ratio. However, this system involves disadvantages like, high design complexity and high manufacturing and maintenance costs. Also, the gear ratio used for starting the vehicle does not depend on the engine load and environmental conditions. Further, the planetary gear system is found to occupy more space and may be difficult while packaging in two-wheeled vehicles.
[005] In another attempt, a Continuously Variable Transmission (CVT) is provided in the starter motor. The CVT has been used to provide a variable gear ratio between the starter motor and the crankshaft. However, the CVT provided would lag in its response speed, as the cranking usually happens in less than 0.3 - 0.5 seconds. The lag will make the CVT inefficient. Also, the lifetime of the CVT is found to be less when compared with the conventional transmission mechanisms. In addition to aforesaid limitations, the CVT include slippage issues in belt and the gear ratio used for starting does not depend on the engine load and environmental conditions.
[006] In yet another attempt, the starter motor is replaced with an Integrated Starter Generator (ISG). In this mechanism, the ISG is directly mounted on the crankshaft. However, adapting an ISG based system for all types of vehicles may not be a feasible option, as it increases the overall weight of the vehicle, which in turn affects the fuel efficiency.
[007] Thus, there is a need in the art for a system for starting a vehicle and a method which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION
[008] In one aspect, the present invention is directed to a system for starting a vehicle. The system includes a rotary electric machine and a gearbox having a plurality of gears arranged to form a desired gear train to achieve a required gear ratio to start the vehicle. The gearbox is coupled with the rotary electric machine and a crankshaft of the vehicle to transmit power from the rotary electric machine to the crankshaft. The system further includes a control unit configured to generate an output signal indicative of the required gear ratio based on one or more predetermined vehicle load parameters. The system further includes an actuator in communication with the control unit. The actuator is configured to receive the output signal from the control unit and align the gears to obtain the required gear ratio for starting the vehicle.
[009] In a further embodiment of the invention, the control unit is configured to determine the required gear ratio based on the one or more predetermined vehicle load parameters to start the vehicle.
[010] In another embodiment of the invention, the control unit includes a detection unit configured for detecting ON conditions of an ignition key and an electric start switch, and a determination unit configured for determining the gear ratio based on the one or more predetermined vehicle load parameters.
[011] In a further embodiment of the invention, the one or more predetermined vehicle load parameters includes an engine temperature, a throttle position and an engine load.
[012] In a further embodiment of the invention, the control unit is configured to generate a high gear ratio output signal when the measured engine temperature is high and engine load is low and generate a low gear ratio output signal when measured engine temperature is less and engine load is high.
[013] In a further embodiment of the invention, the control unit is configured to determine battery voltage of a battery of the vehicle and generate the output signal if the battery voltage is greater than a reference value.
[014] In a further embodiment of the invention, the control unit includes any one of a fuel injection control unit (FI-ECU), a vehicle control unit, and a starter control unit.
[015] In a further embodiment of the invention, the rotary electric machine includes a starter motor.
[016] In a further embodiment of the invention, the gearbox includes a plurality of fixed gear ratio configuration. The plurality of fixed gear ratio configuration includes a first predetermined gear ratio corresponding to a low engine temperature and a high engine load.
[017] In a further embodiment of the invention, the plurality of fixed gear ratio configuration includes a second predetermined gear ratio corresponding to a high engine temperature and a low engine load.
[018] In a further embodiment of the invention, the first predetermined gear ratio is lesser than the second predetermined gear ratio.
[019] In a further embodiment of the invention, the plurality of fixed gear ratio includes the first predetermined gear ratio for a first predetermined condition, the second predetermined gear ratio for a second predetermined condition and an Nth predetermined gear ratio for a Nth predetermined condition, where the number of gear ratios is fixed, and the control unit is configured to provide a signal indicative of the ratios between the fixed gear ratios.
[020] In a further embodiment of the invention, the at least one or more predetermined vehicle load parameters is measured by sensors disposed on the vehicle.
[021] In another aspect, the present invention is directed to a method for starting a vehicle having a rotary electric machine coupled with a crankshaft through a gearbox having plurality of gears arranged to form a desired gear train to achieve a required gear ratio to start the vehicle, a control unit and an actuator in communication with the control unit. The method includes the steps of measuring at least one or more predetermined vehicle load parameters by sensors disposed on the vehicle. The method further includes determining a required gear ratio based on the measured one or more predetermined vehicle load parameters by the control unit. The method further includes generating an output signal indicative of the required gear ratio and transmitting the output signal to the actuator by the control unit. The method further includes receiving the output signal and aligning the gears by the actuator to obtain the required gear ratio for the electric machine to start the vehicle.
[022] In a yet another embodiment of the invention, the method includes a step of detecting ON conditions of an ignition key and an electric start switch by a detection unit of the control unit.
[023] In a yet another embodiment of the invention, the method includes the steps of generating a high gear ratio output signal by the control unit when the measured engine temperature is high and engine load is low and generating a low gear ratio output signal by the control unit when measured engine temperature is less and engine load is high.
[024] In a yet another embodiment of the invention, the method includes the steps of determining battery voltage of a battery of the vehicle by the control unit; generating the output signal by the control unit for the actuator when the battery voltage is greater than a reference value; and communicating the output signal indicative of the required high or low gear ratio to the actuator.

BRIEF DESCRIPTION OF THE DRAWINGS
[025] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 illustrates a right-side view of an exemplary motor vehicle, in accordance with an embodiment of the invention.
Figure 2 illustrates a schematic block diagram of a system for starting the motor vehicle, in accordance with an embodiment of the invention.
Figures 3 to 5 illustrate method flowcharts of starting the motor vehicle, in accordance with an embodiment of the invention.
Figure 6 illustrates a graph of energy consumption reduction for low and high gear ratio configurations, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[026] The present invention relates to a system for starting a vehicle and a method thereof. More particularly, the present invention relates to the system for starting the vehicle with a variable gear ratio for cranking based on an input of an engine load. Thereby, cranking current consumption is reduced and also the start-ability of the engine is improved.
[027] Figure 1 illustrates an exemplary motor vehicle 10, in accordance with an embodiment of the invention. The motor vehicle 10 is a two-wheeler vehicle. However, in some embodiments, the motor vehicle 10 may be a three-wheeler vehicle. The present invention may also be applied in other vehicles as well. In the illustrated embodiment, the two-wheeler motor vehicle 10 comprises an Internal combustion engine 12 that can be vertically disposed. The Internal combustion engine 12 may be a single-cylinder type Internal combustion engine. In another embodiment, the Internal combustion engine 12 may also be a twin-cylinder or multi-cylinder type Internal combustion engine. The motor vehicle 10 includes a front wheel 14, a rear wheel 16, a frame member, a seat assembly 18 and a fuel tank 20.
[028] The frame member of the vehicle 10 includes a head pipe 22, a main tube 24, a down tube (not shown), and seat rails (not shown). The head pipe 22 is adapted to support a steering shaft (not shown) and two telescopic front suspensions 26 (only one shown) attached to the steering shaft through a lower bracket (not shown). The telescopic front suspensions 26 are adapted to support the front wheel 14. The upper portion of the front wheel 14 may be covered by a front fender 28 which can be mounted to the lower portion of the telescopic front suspension 26 at the end of the steering shaft. The motor vehicle 10 further includes a handlebar 30 which is fixed to an upper bracket (not shown) and can be rotated to both sides of the vehicle 10. The vehicle 10 further includes a head light 32 and an instrument cluster (not shown) and are arranged on an upper portion of the head pipe 22. A visor guard (not shown) may be provided on the upper portion of the head pipe 22.
[029] The frame member of the vehicle 10 may further include a down tube (not shown) that may be located in front of the Internal combustion engine 12 and in one embodiment may extend slantly downward from the head pipe 22. The main tube 24 of the frame member may be located above the Internal combustion engine 12 and may extend rearwardly from the head pipe 22. The Internal combustion engine 12 may be mounted at the front to the down tube and a rear of the Internal combustion engine 12 may be mounted at the rear portion of the main tube 24. In the illustrated embodiment shown in Figure 1, the Internal combustion engine 12 is mounted vertically, with a cylinder block extending vertically above a crankcase. In an alternative embodiment, the Internal combustion engine 12 may be mounted horizontally (not shown) with the cylinder block extending horizontally and forwardly from the crankcase. In yet another embodiment, the cylinder block may be disposed rearwardly of the down tube.
[030] The fuel tank 20 of the vehicle 10 is generally mounted on the horizontal portion of the main tube 24. Seat rails may be joined to the main tube 24 and may extend rearwardly to support a seat assembly 18. A rear swing arm 34 is connected to the frame member to swing vertically, and the rear wheel 16 is connected to a rear end of the rear swing arm 34. Generally, the rear swing arm 34 is supported by a mono rear suspension 36 or through two suspensions on an either side of the motor vehicle 10.
[031] A taillight unit 33 is disposed at the end of the motor vehicle 10 and at the rear of the seat assembly 18. A grab rail 35 may also be provided on the rear of the seat rails. The rear wheel 16 arranged below the seat assembly 18 rotates by a driving force of the Internal combustion engine 12 transmitted through a chain drive (not shown) from the Internal combustion engine 12. A rear fender 38 may be disposed above the rear wheel 16.
[032] Further, an exhaust pipe 40 of the motor vehicle 10 may extend vertically downward from the Internal combustion engine 12 up to a point and then may extend below the Internal combustion engine 12, longitudinally along the vehicle length before terminating in a muffler 42. The muffler 42 is typically disposed adjoining the rear wheel 16.
[033] Furthermore, a rotary electric machine 44 (schematically shown in Figure 2) for electrically starting the motor vehicle 10 is provided. In one embodiment of the present invention, the rotary electric machine 44 is a starter motor. The rotary electric machine 44 is connected to the Internal combustion engine 12 through a gearbox 46 (schematically shown in Figure 2). The rotary electric machine 44 is adapted to receive a power from a battery 54 (schematically shown in Figure 2) of the motor vehicle 10 and rotate a crankshaft 48 (schematically shown in Figure 2) of the Internal combustion engine 12. Typically, the crankshaft 48 is further connected to a piston (not shown) of the Internal combustion engine 12.
[034] Figure 2 illustrates a schematic block diagram of a system 100 for starting the motor vehicle 10, in accordance with an embodiment of the invention. The system 100 includes the rotary electric machine 44 and the gearbox 46 having a plurality of gears. The plurality of gears is arranged to form a desired gear train to achieve a required gear ratio to start the vehicle 10. In other words, the gearbox 46 consists of different gears, wherein each combination of gears on meshing provides a different gear ratio. The gearbox 46 is coupled with the rotary electric machine 44 and the crankshaft 48 of the vehicle 10 such that a power can be transmitted from the rotary electric machine 44 to the crankshaft 48, thereby, the gearbox 46 helps in operating the rotary electric machine 44 and the crankshaft 48 at a different torque-speed characteristics which is based on cold starting or hot starting conditions.
[035] Referring further to Figure 2, the system 100 further includes a control unit 102. In an embodiment, the control unit 102 is configured within an Electronic Control Unit (ECU) (not shown) of the vehicle 10. In another embodiment, the control unit 102 is configured as a separate module which can be in communication with the ECU of the vehicle 10. In yet another embodiment, the control unit 102 includes a fuel injection control unit (FI-ECU) or a vehicle control unit or a starter control unit.
[036] In some embodiments, the control unit 102 includes one or more additional components such as, but not limited to, a memory unit, an input/output module, a pre-processing module etc. In another embodiment, the system 100 includes more than one of same or similar control unit(s) 102.
[037] In another embodiment, the control unit 102 includes only a processor which may be required to process the received instructions / signals from one or more inputs device like sensors and / or switches and process the same. In yet another embodiment, the system 100 is in communication with an analytic module which is configured to perform additional analysis of the communication information received from sensors 56 of the vehicle 10.
[038] In some embodiments, the memory unit in communication with the control unit 102 is capable of storing machine executable instructions. Further, the control unit 102 is capable of executing the machine executable instructions to perform the functions described herein. The control unit 102 is in communication with the components such as the pre-processing module and the analytic module. In another embodiment, the control unit 102 is embodied as a multi-core processor, a single core processor, or a combination of one or more multi-core processors and one or more single core processors. For example, the control unit 102 is embodied as one or more of various processing devices, such as a coprocessor, a microprocessor, a controller, a digital signal processor (DSP), a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), a hardware accelerator, a special-purpose computer chip, or the like. In yet another embodiment, the control unit 102 is configured to execute hard-coded functionality. In still another embodiment, the control unit 102 is embodied as an executor of instructions, where the instructions are specifically configured to the control unit 102 to perform the steps or operations described herein for carrying-out starting of the vehicle 10.
[039] In an embodiment, the control unit 102 includes a detection unit 108 configured for detecting ON conditions of an ignition key 50 and an electric start switch 52 of the vehicle 10. In another embodiment, the control unit 102 includes a determination unit 110 which is configured to determine the gear ratio based on the one or more predetermined vehicle load parameters. In an embodiment of the present invention, the one or more predetermined vehicle load parameters includes, but not limited to, an engine temperature, a throttle position and an engine load. The predetermined vehicle load parameters are measured by the sensors 56 disposed on the vehicle 10. The sensors 56 may include, but not limited to, a temperature sensor and a throttle position sensor.
[040] In an embodiment of the present invention, the control unit 102 is configured to generate an output signal indicative of a required gear ratio based on the one or more predetermined vehicle load parameters obtained from the sensors 56 to start the vehicle 10. Particularly, the control unit 102 provides the output signal to an actuator 104 of the system 100 for aligning the required gear ratio for cranking the Internal combustion engine 12 of the vehicle 10.
[041] In an embodiment, the control unit 102 is configured to generate a high gear ratio output signal when the measured engine temperature is high and engine load is low. In another embodiment, the control unit 102 is configured to generate a low gear ratio output signal when the measured engine temperature is less, and the engine load is high.
[042] In an embodiment, the control unit 102 is configured to determine battery voltage of the battery 54 of the vehicle 10 and generate an output signal if the battery voltage is greater than a reference value. Thereafter, the determination unit 110 of the control unit 102 communicates either the high gear ratio signal or the low gear ratio signal to the actuator 104.
[043] The actuator 104 of the system 100 which is in communication with the control unit 102 is configured to receive the output signal from the control unit 102. Upon receiving the output signal, the actuator 104 aligns or moves the gears of the gearbox 46 to obtain the required gear ratio for starting the vehicle 10 by cranking the engine 12. In an embodiment, the actuator 104 may include a set of linear actuators or a rotary actuator with linear motion converters which are activated to align or move a required gear in the gearbox for obtaining the required gear ratio.
[044] In an embodiment, the gearbox 46 includes a plurality of fixed gear ratio configuration. In another embodiment, the plurality of fixed gear ratio configuration includes a first predetermined gear ratio corresponding to a low engine temperature and a high engine load. In yet another embodiment of the present invention, the plurality of fixed gear ratio configuration includes a second predetermined gear ratio corresponding to a high engine temperature and a low engine load. In still another embodiment, the first predetermined gear ratio is lesser than the second predetermined gear ratio.
[045] In another embodiment, the plurality of fixed gear ratio includes the first predetermined gear ratio for a first predetermined condition, the second predetermined gear ratio for a second predetermined condition and an Nth predetermined gear ratio for a Nth predetermined condition, where the number of gear ratios is fixed, and the control unit 102 is configured to provide a signal indicative of the ratios between the fixed gear ratios.
[046] In yet another embodiment, the memory unit may store the data pertaining to the engine temperature and engine load for which the low gear ratio signal is required to be generated. When the measured engine temperature is less and the engine load is high, the control unit 102 may obtain the data from the memory device corresponding to the required low gear ratio and generate the output signal accordingly.
[047] In still another embodiment, the memory unit may store the data pertaining to the engine temperature and engine load for which the high gear ratio signal is required to be generated. When the measured engine temperature is high and the engine load is low, the control unit 102 obtains the data from the memory device corresponding to the required high gear ratio and generate the output signal accordingly.
[048] Similarly, in still another embodiment, the memory stores the details of the plurality of fixed gear ratio configuration that includes a first predetermined gear ratio corresponding to a low engine temperature and a high engine load, and the plurality of fixed gear ratio configuration that includes a second predetermined gear ratio corresponding to a high engine temperature and a low engine load.
[049] Further, in still another embodiment, the memory stores the details of the plurality of fixed gear ratio having the first predetermined gear ratio for a first predetermined condition, the second predetermined gear ratio for a second predetermined condition and an Nth predetermined gear ratio for a Nth predetermined condition, where the number of gear ratios is fixed. The control unit 102 obtains the details of the gear ratios from the memory based on the predetermined conditions which may correspond to the engine load conditions.
[050] Figure 3 illustrate a method 300 flowchart for starting the motor vehicle 10, in accordance with another aspect of the invention.
[051] At a step 302, at least one or more predetermined vehicle load parameters is measured by the sensors 56 disposed on the vehicle 10. The detection unit 108 of the control unit 102 will simultaneously detect the ON conditions of the ignition key 50 and the electric start switch 52. The one or more predetermined vehicle load parameters includes, but not limited to, the engine temperature, the throttle position and the engine load. The measured one or more predetermined vehicle load parameters are communicated to the control unit 102.
[052] At a step 304, the control unit 102 based on the measured one or more predetermined vehicle load parameters determines the required gear ratio for cranking the Internal combustion engine 12 for starting the vehicle 10. The required gear ratio in other words would mean an ideal gear ratio among the multiple gear ratios available in the gearbox 46 of the vehicle 10 such that the cranking will be efficient in that particular engine condition.
[053] At a step 306, the output signal indicative of the required gear ratio is generated and transmitted to the actuator 104 by the control unit 102. At a step 308, the output signal is received for aligning the gears by the actuator 104 to obtain the required gear ratio (low or high gear ratio) for the rotary electric machine 44 to start the vehicle 10.
[054] Referring to Figure 4, when the measured engine temperature is high and the engine load is low, at a step 400, a high gear ratio output signal is generated by the control unit 102. The control unit 102 communicates the output signal to the actuator 104 for aligning the gears of the gearbox 46 to the high gear ratio. When the high gear ratio is obtained, the rotary electric machine 44 is required to be operated such that a low torque and high speed condition is obtained. Since the power required to drive the rotary electric machine 44 for generating the low torque and high speed condition is optimized based on the load conditions of the vehicle 10, the battery power is optimally utilized and thereby improving the rotary electric machine performance.
[055] In alternate embodiment, when the measured engine temperature is less and the engine load is high, at a step 402, a low gear ratio output signal is generated by the control unit 102. The control unit 102 communicates the output signal to the actuator 104 for aligning the gears of the gearbox 46 to the low gear ratio. When the low gear ratio is obtained, the rotary electric machine 44 is now required to be operated such that a high torque and low speed condition is obtained. Since the power required to drive the rotary electric machine 44 for generating the high torque and low speed condition is optimized based on the load conditions of the vehicle 10, the battery power is optimally utilized and thereby improving the rotary electric machine performance.
[056] As explained hereinabove, in an embodiment of the engine condition, a less torque and high speed may be required to crank the Internal combustion engine 12 efficiently. As explained hereinabove, in another embodiment of the engine condition, a high torque and low speed is required to crank the Internal combustion engine 12 efficiently. Thus, the present invention provides a solution where a different gear ratios are provided based on the engine conditions, so as to crank the engine 12 efficiently.
[057] Referring to Figure 5, in another embodiment, the method further includes, determining the battery voltage of the battery 54 of the vehicle 10 by the control unit 102, at a step 500. After the battery voltage is determined and when the battery voltage is greater than the reference value, at a step 502, the output signal is generated by the control unit 102 for the actuator 104. The determination unit 110 of the control unit 102 communicates either the high gear ratio signal or the low gear ratio signal to the actuator 104 at a step 504.
[058] With reference to Figure 6, it is evident that by shifting to the high gear ratio from the low gear ratio for cranking the engine 12, there is approximately 13.25% reduction in energy consumption by the rotary electric machine 44.
[059] The system and method as disclosed in the present invention provides multiple torque-speed characteristics, which in turn improves the efficiency and performance of cranking. In other words, the present invention provides a different gear ratios for starting the vehicle at different operating points and thus making the rotary electric machine of the vehicle to work efficiently.
[060] The system and method as disclosed in the present invention will be able to choose the required gear ratio based on engine load requirement. Thus, the rotary electric machine will be able to operate at different operating points.
[061] The system as disclosed in the present invention is not complicated and it does not require high maintenance cost. The system also reduces energy consumption and is fast, unlike the CVT’s.
[062] In the existing designs, the starting system typically operated at a fixed gear ratio, irrespective of engine load requirements. However, the system and method as disclosed in the present invention takes an input of engine load and then decides which gear ratio has to be used for cranking, thereby cranking current consumption can be reduced and also engine start-ability can be improved.
[063] The present invention overcomes the limitations of high costs, two or more inputs associated with planetary gears, slippage, less compact, less efficient and more response time as found in the prior arts to obtain different torque-speed characteristics using CVT and planetary gears.
[064] Since the system and method disclosed in the present invention provides a solution which can choose the required gear ratio for starting application based on engine load requirement, it can be operated at various torque points and is cost-effective, and simple in terms of manufacturing and maintenance unlike planetary gears and also has less response time, unlike CVT. Thus, the system and method as provided in the present invention make it better than the existing systems in the prior arts.
[065] The system and method as disclosed in the present invention can select the gear ratio for starting application based on the engine load. The gear ratio can be varied for each cranking trial based on engine load requirement, which reduces the system complexity.
[066] The system and method in the present invention improves engine cranking performance since the vehicle load parameters are considered for determining ideal gear ratios.
[067] Thus, by providing a rotary electric machine with variable gear ratio may enable achieving equivalent energy consumption as that of an ISG based system. Thus, the present invention enables optimal energy consumption without impacting the fuel efficiency of the vehicle. Also, the system and method in the present invention provides an improved emission control.
[068] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.