HYBRID POWERTRAINS

Abstract

A method and system of operating an internal combustion engine (ICE) of a hybrid powertrain system for powering a vehicle or stationary apparatus having a variable load demand includes arrangements and configurations of operating the ICE to charge/recharge capacitive energy storage, such as ultra-capacitors, during acceleration or high load demand on the ICE. Operation of the ICE can be transitioned from one mode of operation to another, more efficient, mode of operation during charging and high load. The present invention provides fuel efficiency/economy benefits when charging the capacitive energy storage during high load situations.

Claims

1. A method of operating a hybrid power system for powering a vehicle or stationary apparatus having a variable load demand, the method comprising: operating an internal combustion engine (ICE); and operating a generator or electric machine to charge/recharge capacitive energy storage of at least one electrical energy storage device during acceleration or high load demand on the ICE.

2. The method of claim 1, wherein on-board charging is used to recover the energy in the capacitive energy storage such that the energy is available for a subsequent acceleration cycle of the vehicle.

3. The method of claim 1, wherein the acceleration or high load demand is at or near full throttle opening of the ICE.

4. The method of claim 1, wherein the acceleration or high load demand is at least at 30% or above of throttle opening or of maximum torque capacity of the ICE.

5. The method of claim 1, further comprising controlling operation of the ICE to operate within a desired range of revolutions per minute (rpm) or at desired rpm to charge/recharge the capacitive energy storage.

6. The method of claim 1, wherein the capacitive energy storage includes at least one ultra-capacitor, at least one super capacitor, or a combination of the at least one ultra-capacitor and the at least one super capacitor.

7. The method of claim 1, further comprising transitioning operation of the ICE from a first mode of operation to a second, more efficient mode of operation for the ICE than the first mode of operation, when charging/recharging capacitive energy storage of at least one electrical energy storage device.

8. The method of claim 7, wherein the ICE is controlled to operate in the second mode of operation while the capacitive storage of at least one electrical energy storage device is used to power at least one said electric machine.

9. The method of claim 7, wherein the second mode of operation of the ICE is a higher fuel efficiency mode of operation and/or at a preferred emissions output of the ICE than the first mode of operation.

10. The method of claim 7, wherein the ICE is controlled to return to the first mode of operation when the capacitive energy storage is charged/recharged to or above a threshold voltage or is controlled to maintain the capacitive energy storage at or above a threshold voltage or charge level.

11. The method of claim 7, further comprising optimising weighted average fuel efficiency of the ICE by controlling the ICE to transition from the first mode of operation to the second mode of operation to charge/recharge the capacitive energy storage when the second mode of operation is more fuel efficient for the ICE than the first mode when the capacitive energy storage is to be charged/recharged.

12. The method of claim 1, wherein, when the method is applied to operation of a vehicle, regenerative braking is not provided or is not used to charge/recharge the capacitive energy storage when the ICE is operated in a mode to charge/recharge the capacitive energy storage.

13. The method of claim 1, wherein, at relatively lower efficiency operational mode of the ICE the at least one electrical energy storage device is used to power or augment powering of the vehicle or the stationary device, and at a relatively higher efficiency operational mode of the ICE the ICE is used to charge/recharge the at least one electrical energy storage device.

14. The method of claim 1, wherein the ICE is put to an idle mode or turned off during a period when the at least one electrical energy storage device is powering the vehicle or the stationary device, or wherein the ICE is operated to charge/recharge the at least one electrical energy storage device when an output voltage of the at least one electrical energy storage device falls to or below a threshold value.

15. The method of claim 1, wherein, during constant speed states, the energy in the capacitive energy storage is used first then charging/recharging is (re)commenced to provide a power requirement to sustain constant speed.

16. The method of claim 1, wherein rpm of the ICE is varied to ensure that a voltage delta between charging voltage and a voltage of the capacitive energy storage is such that a sufficient current is provided so that the product of voltage and current supplied produces the required power to maximize fuel efficiency reductions and charge the capacitive energy storage so that the stored electrical energy is available for acceleration states.

17. A hybrid power system for powering a vehicle or stationary apparatus having a variable load demand, the system comprising: an internal combustion engine (ICE) controlled to operate a generator or electric machine to charge/recharge capacitive energy storage of at least one electrical energy storage device during acceleration or high load demand on the ICE.

18. The system of claim 17, wherein the acceleration or high load demand is at full throttle opening of the engine.

19. The system of claim 17, wherein the acceleration or high load demand is at least at 30% or above of throttle opening or of maximum torque capacity of the ICE.

20. The system of claim 17, further comprising: at least one electrical energy storage device including the capacitive energy storage; at least one internal combustion engine (ICE) operatively connected to drive a charging system, such as an on-board charging system and/or an electric power source, such as a generator or electric machine, for use in charging/recharging at least the capacitive energy storage; and a controller arranged and configured to control the ICE to transition operation from a first mode to a second mode more fuel efficient than the first mode when charging/recharging the capacitive energy storage.

21. The system of claim 17, wherein the ICE is configured to operate within a desired range of revolutions per minute (rpm) in the second mode sufficient to charge/recharge the capacitive storage of the at least one energy storage device.

22. The system of claim 20, wherein the controller is configured to operate the ICE to charge/recharge the capacitive energy storage to maintain the at least one electrical energy storage device and/or the capacitive energy storage at or above a minimum voltage.

23. The system of claim 20, wherein controller is configured to transition operation of the ICE from a first mode to a second mode, the second mode being of higher rpm that the first mode, to charge/at least the capacitive energy storage.

24. The system according to claim 20, wherein a state of the system determines operation of the on-board charging system and/or an electric power source and wherein the controller, such as an ECU, is configured to receive one or more inputs of: voltage, current, throttle position, brake pedal position, torque demand, rpm and speed.

25. The system according to claim 24, wherein the states are identifiable by the values of the inputs: during the stationary state the current will be zero, the throttle position sensor will be zero, and the brake switch on; or during deceleration the current will be zero, the throttle position will be zero, the speed will be declining in time, and the brake switch may be on or off; or during acceleration the current will be greater than zero, the throttle position greater than zero, and the speed will be increasing with time; or during constant speed the current will be greater than zero, the throttle will be greater than zero, and the change in speed in time will be in a small range; or during deceleration and with brake on regeneration can be activated.

26. The system according to claim 20, including an optimized charging system and/or an electric power source for high voltage output at low rpm (low Kv) and high output current at low rpm or including an optimized internal combustion engine (ICE) with high torque output at low rpm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0174] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0175] FIG. 1 is the World Motorcycle Test Cycle (WMTC) Stage 1 for two wheelers with the lower speed top speed curve for 150 cc capacity or less and the high top speed curve for greater than 150 cc.

[0176] FIG. 2 is the components of the on-board charging system for ultra-capacitor.

[0177] FIG. 3 is the torque speed characteristic for the same electric machine when terminated in wye and delta showing optimized switch point.

[0178] FIG. 4 shows the inputs required for the optimized ECU control of the on-board charging system and its values for stationary, deceleration, acceleration and constant speed states.

[0179] FIG. 5 shows an example of the IDC (Indian Drive Cycle).

[0180] FIGS. 6 to 8 show configurations of powertrain arrangements relating to one or more embodiments of the present invention.

DETAILED DESCRIPTION

[0181] Referring to FIG. 1 it describes the World Motorcycle Test Cycle (WMTC) Stage 1 drive cycle. This is the typical world motorcycle test cycle for two wheelers with the low top speed curve for 150 cc capacity or less. The cycle can be broken down into stationary, acceleration, constant speed and deceleration states. WMTC Tests were conducted on various 100 cc two-wheelers with CVT transmission systems. Table 1 summarizes the average % fuel used for each state.

[0182] The test was repeated using a two-wheeler retrofitted with a Brushless Direct Current (BLDC) electric hub motor and removal of the internal combustion engine. Weight of the vehicle was maintained. An ultra-capacitor pack of 187.5 Farad consisting of sixteen 3000 Farad cells connected in series with active balancing was charged to 40V at the start of the test. The voltage was recorded to determine the energy used during discharge. Table 2 summarizes the energy used by an internal combustion engine with gasoline fuel compared to an electric hub motor drive using ultra-capacitors.

[0183] For energy calculations a constant of 34,342 Joules per millilitre (mL) of gasoline is used. Equation of:

W(Joules)=C(Vmax.sup.2Vmin.sup.2)

is used for ultra-capacitor energy where C is 187.5 Farad.

[0184] For the same acceleration profile the electric ultra-capacitor powertrain used only 20% of the energy the internal combustion engine used with gasoline. During the longest constant speed period of the WMTC cycle the electric ultra-capacitor powertrain used only 10% of the energy the internal combustion engine used with gasoline for the same period.

[0185] Similar results are obtained for other acceleration and constant speed sections of the WMTC drive cycle.

[0186] The difference in energy use during acceleration between the ultra-capacitor powertrain and the internal combustion engine is accounted for by the inefficiency of the petrol motor as compared to the electric machine and ultra-capacitor combination, however the significant variation at constant speed is due to the inefficiency of the transmission system. The electric drive with ultra-capacitor only supplies the power required to keep at constant speed. However, the internal combustion engine with CVT transmission keeps the rpm as high as 5000 rpm (max torque) resulting in increased wasted energy.

[0187] To maximize the use of electric powertrain but eliminate any need for dependence on external charging an on-board charging system (10) is used and is described in FIG. 2.

[0188] The system includes an internal combustion engine (ICE) (3) which may be optimized for high torque at low rpm; an optional torque multiplier (4); a generator (5) a rectifier/regulator (6); an ultra-capacitor pack/s (7); and an electric machine controller (8).

[0189] The internal combustion engine (ICE) (3) is connected to a generator (5) or through a torque multiplier (4).

[0190] This system (10) charges the ultra-capacitor (7) and/or provides power to the electric machine/s (9) through an electric machine/s controller (8). The generator (5) could also be an electric machine replacing electric machine/s (9) or used in combination with electric machine/s(9).

[0191] When generator (5) is acting as an electric motor it can power assist the ICE (3) to reduce load on the ICE (3).

[0192] In embodiments the generator (5) which may be in the form of a BLDC Generator (5). The generator (5) may be designed to have a low Kv using an increased number of turns per phase and terminated in wye configuration, which provides high voltage output at low rpm.

[0193] The generator (5) is also required to have a large current output at low rpm while avoiding saturation inefficiencies. This may be achieved by, but not limited to, increasing the strength of the magnets, increasing the physical size, changing the core material and/or adjusting the air gap.

[0194] A torque multiplier (4), which may be in the form of a fixed gear ratio between the internal combustion engine (ICE) (3) and the BLDC generator (5) can be used to optimise the matching of the torque capacity of the ICE (3) and output characteristics of the BLDC generator (5)

[0195] The ICE (3) used in the on-board charging system (10) may be optimized to provide a high torque at low rpm and is understood by those of skill in the art.

[0196] The ICE (3) may be connected to a clutch/transmission (11) and drive wheel (12) to provide propulsion.

[0197] A combination of low Kv BLDC generator (5), optimized ICE (3) for high torque at low rpm, and a fixed gear reduction torque multiplier (4) allow for a high voltage output to be supplied to the electric machine for top speed and high charging current to the ultra-capacitor pack/s (7) for fast charging. The ICE (3) operates at its sweet spot during charging of the ultra-capacitor.

[0198] In embodiments, to charge ultra-capacitors at a constant current the difference in voltage between the ultra-capacitor's (7) voltage and the output voltage of the generator (5) needs to be kept constant. As the ultra-capacitor (7) is being charged its voltage will increase.

[0199] To maintain the constant current so that rapid charging occurs the voltage output of the generator (5) must increase. The voltage of the ultra-capacitors (7) is monitored and the rpm of the generator (5) is controlled to maintain constant charging amperage up to full capacity.

[0200] During acceleration a high torque is required from the electric drive machine (7). High torque is achieved by terminating the windings in a wye termination. The disadvantage of this is that the top speed is reduced unless an increase in voltage is available.

[0201] For the same electric drive machine/s (9) a 1.73 multiple increase in Kv constant (rpm/volt) is achieved by terminating in delta. As speed is directly related to the Kv constant the top speed is also increased with reduced torque capacity.

[0202] Referring to FIG. 3, for the same electric machine (9) a plot of the Torque (Nm) vs. Road Speed (km/hr.) characteristic is shown when terminated in wye (11) and when terminated in delta (12).

[0203] At low speed the wye termination has a greater torque but at particular point (13) the delta termination continues to have a higher speed and higher torque characteristic.

[0204] The additional benefit is that in delta termination the Kv is higher which results in a lower voltage requirement to achieve the same rpm. This allows more energy to be drawn from the ultra-capacitor and the on-board charging system, which in turn allows operation at higher speeds with lower rpm.

[0205] In embodiments to achieve an optimum torque and speed characteristic and a reduction in rpm requirement for the on-board charging system an electric on the fly switching between wye and delta is implemented. This is implemented by using a contact relay that is controlled by the ECU microprocessor. The phase ends of the electric machine/s' (9) windings are taken to a contact relay. During switching, the current draw from electric machine controller/s (8) and or throttle is disabled for safe smooth transition.

[0206] Referring to FIG. 4, to operate efficiently the on-boarding charging system (10) needs to know what state; stationary (15), deceleration (16), acceleration (17), constant speed (18) the vehicle is in. The inputs (14); Current, Voltage, Throttle Position, Vehicle Speed and Brake can be read by the ECU microprocessor.

[0207] During the stationary state (15) the current will be zero, the throttle position sensor will be zero, and the brake switch on. During deceleration (16) the current will be zero, the throttle position will be zero, the speed will be declining in time, and the brake switch may be on or off.

[0208] During acceleration (17) the current will be greater than zero, the throttle position will be greater than zero, and the speed will be increasing with time. During constant speed (18) the current will be greater than zero, the throttle will be greater than zero, and the change of speed in time will be in a small range.

[0209] During deceleration (16) the brake may be on in which case regeneration can be activated by the electric machine controller/s (8).

[0210] In embodiments to optimize the operation of the on-board charging system (10) the states; stationary (15), deceleration (16), acceleration (17), constant speed (18) are identified by values of inputs (14); Current, Voltage, Throttle Position, Vehicle Speed and Brake position. Additionally the fuel consumption vs torque vs rpm map is stored in an ECU microprocessor and sweet spot known for the Internal Combustion Engine. The inputs are read by the ECU microprocessor to determine the operation of the on-board charging system to optimize performance, fuel and emission saving and maintain vehicle operation speed and load requirements.

[0211] Referring to Table 3 which summarizes the fuel consumed on a WMTC Test Cycle.

[0212] TABLE 3 shows the average % fuel used in mL by a 100 cc two-wheeler with CVT transmission in the states of stationary, acceleration, constant speed and deceleration during the WMTC Stage 1 test cycle.

TABLE-US-00003 TABLE 3 Total Total Average Mode Time % Time Fuel (mL) % Fuel mL/s Acceleration 194 32.2 34.68 41.3 18.1 Deceleration 140 23.2 18.51 22.1 15.1 Stationary 109 18.1 4.22 5.0 5.3 Constant 160 26.5 26.51 31.6 21.1 Totals 603 100 83.92 100

[0213] During deceleration 22.1% of the total fuel of the cycle is consumed as wasted energy. This is due to the closed throttle position on a carburettor while the petrol motor draws fuel from the idle port.

[0214] During stationary periods 5.0% of the total fuel of the cycle is consumed as wasted energy. This is due to idling of motor at 1500 rpm.

[0215] During states of deceleration (16) and stationary (15), the vehicle does not do work.

[0216] In embodiments the operation of the on-board charging system (10) can determine by the states (15-18) the vehicle is in.

[0217] To maximize fuel and emissions savings the on-board charging system's ICE (3) can be turned off when work is not being done by the vehicle and the ultra-capacitor pack (7) is fully charged. Work is not being done during stationary (15) and deceleration (16) states. If the ultra-capacitor pack (7) is not fully charged the ultra-capacitor (7) is rapidly charged during these states until it is full using constant current and running the ICE (3) at its sweet spot. This could involve the engine throttle being opened to produce sufficient power required to charge the UCs and run at its sweet spot. Once the ultra-capacitor's (7) full capacity is reached then the on-board charging system (10) including the ICE (3) is turned off.

[0218] To maximize the fuel and emission saving during acceleration state the energy in the ultra-capacitor (7) is discharged.

[0219] The on-board charging system (10) can be used to recharge the UCs during their discharge and/or can be used to replace the UC power when the UCs drop to or below a threshold voltage/current they are able to deliver by the ICE generator providing a higher or matched charging current to discharge current.

[0220] In ideal cases the capacity of the ultra-capacitor (7) is selected for the typical acceleration gradient and acceleration time period so that the full acceleration can be captured on the stored energy of the ultra-capacitor (7).

[0221] The ICE (3) can be run at its sweet spot during charging of the ultra-capacitors to increase available time to run in electric powertrain or provide energy for further acceleration states.

[0222] During constant speed states the energy in the ultra-capacitor (7) is used first then the on-board charging system (10) turned on to provide power requirement to sustain constant speed.

[0223] At any time while the on-board charging system (10) is on, the rpm of the ICE (3) can be varied to ensure that the voltage delta between the on-board charging system (10) and the ultra-capacitor (7) is such that it induces a sufficient current so that the product of voltage and current supplied produces the required power to maximize fuel and emissions reductions and charge the ultra-capacitor (7) so that the energy is more readily available for acceleration (17) states.

[0224] At any time, the ultra-capacitor (7) is being discharged and the on-board charging system (10) is off, the on-board charging system (10) may be turned on at any time, to sustain voltage and load demand by the application.

[0225] In embodiments during periods when the brake is applied, the electric machine controller/s (8) may activate regeneration to provide electric braking and charge the ultra-capacitor (7).

[0226] In various embodiments the energy stored in the ultra-capacitor (7) can be used during acceleration (17) states. The energy can be recovered using the on-board generator (10) during acceleration, low constant speed or deceleration states where torque demand is sufficiently low to run the ICE (3) at its sweet spot.

[0227] In various embodiments during constant low speed states energy stored in the ultra-capacitor (7) is discharged until a low voltage set point is reach. At this point the on-board charger (10) is turned on to recharge the ultra-capacitor with the ICE (3) running at its sweet spot.

[0228] In embodiments during deceleration (16) states the ICE (3) is turned off when the ultra-capacitor pack (7) is fully charged.

[0229] In embodiments during stationary (15) states the ICE (3) is turned off when the ultra-capacitor pack (7) is fully charged.

[0230] In embodiments during acceleration (17) states the energy stored in the ultra-capacitor (7) is discharged until a low voltage set point is reached. At this point the on-board charger (10) is turned on to recharge the ultra-capacitor (7).

[0231] In embodiments during acceleration (17) states the energy stored in the ultra-capacitor (7) is discharged. If there is sufficient torque to run the ICE (3) at its sweet spot during acceleration the on-board charger (10) is turned on to recharge the ultra-capacitor (7).

[0232] In various embodiments, the ECU microprocessor may store history of states over time to predict the best control strategy to implement for the on-board charging system (10).

[0233] TABLE 4 is a comparison of energy used for first acceleration and longest constant speed section of the WMTC test cycle for a 100 cc moped and a fully electric moped using an electric machine in rear wheel.

TABLE-US-00004 TABLE 4 POWERTRAIN TYPE Section of WMTC Internal Combustion Electric Hub Motor Test Cycle Engine/Gasoline Fuel with Ultracapacitor Longest Constant 11.27 ml (387034 Joules) (35.6 V Vmax to 28.28 V Speed section WMTC Vmin (43875 Joules) First Acceleration 1.48 ml (50826 Joules) 39.78 V Vmax to 37.76 V of WMTC Vmin (14665 Joules)

[0234] A first-generation system as part of the development process of the present invention is described below. The original test results for a first-generation system are shown in TABLE 5 below.

[0235] The test cycle shown is FIG. 5 is called IDC (Indian Drive Cycle) which was the standard test cycle for two-wheelers in India at the time.

[0236] The results proved a 38% reduction in fuel consumption for the test cycle compared to a baseline conducted on a 100 cc two-wheeler with CVT transmission. The fuel consumption is broken down into acceleration, stationary, charging and deceleration sections in millilitres (ml).

TABLE-US-00005 TABLE 5 Summary - data logs No. of cycles (ignoring Fuel/Speed Hybrid Voltage/ first file (ARAI) Program ID Current cycle) Notes Test A EngCt1005 No file 7 Voltage adjust 17_23_34 Test B EngCt1005 Test006csv 7 10_50_53 Test C EngCt1007 Test007csv 4 Change lower 11_21_35 voltage and high speed fuel cut Test D EngCt1008 Test008csv 4 Change to lower 11_54_12 fuel cut out speed Test E EngCt1008 Test010csv 12 16_42_48

[0237] Results

TABLE-US-00006 Test C 11_54_12 Fuel Total Fuel used Fuel save compared electric Charging Fuel Decel Total Fuel to baseline Average Cycle (Litres) (Litres) (Litres) (Litres) 0.01018 fuel save 1 0 0.00612027 0.000686874 0.006807141 33.13% 35% 2 0 0.00533641 0.001154757 0.006491167 36.24% 3 0 0.00557625 0.000957789 0.006534043 35.81% 4 0 0.00593892 0.000739575 0.006678498 34.40%

TABLE-US-00007 Test E 16_42_48 Fuel Total Fuel used Fuel save compared electric Charging Fuel Decel Total Fuel to baseline Average Cycle (Litres) (Litres) (Litres) (Litres) 0.01018 fuel save 1 0 0.005273931 0.001234236 0.006508167 36.07% 38% 2 0 0.004774961 0.001082273 0.005857234 42.46% 3 0 0.005445791 0.001193377 0.006639168 34.78% 4 0 0.005126517 0.001258192 0.006384709 37.28% 5 0 0.00538188 0.001241119 0.006622999 34.94% 6 0 0.004866179 0.001060139 0.005926318 41.78% 7 0 0.005422308 0.001200486 0.006622794 34.94% 8 0 0.005214421 0.001062089 0.00627651 38.34% 9 0 0.005246865 0.001121837 0.006368702 37.44% 10 0 0.004922512 0.001094775 0.006017287 40.89% 11 0 0.005397035 0.001113345 0.00651038 36.05% 12 0 0.004786285 0.001046696 0.005832981 42.70%

TABLE-US-00008 TestC 11_21_35 Fuel Total Fuel used Fuel save compared electric Charging Fuel Decel Total Fuel to baseline Average Cycle (Litres) (Litres) (Litres) (Litres) 0.01018 fuel 1 0 0.005356275 0.000714215 0.00607049 40.37% 39% 2 0 0.005737186 0.001105474 0.00684266 32.78% 3 0 0.004886485 0.001132035 0.00601852 40.88% 4 0 0.005207725 0.000885805 0.00609353 40.14%

TABLE-US-00009 Test A 17_23_34 Fuel Total Fuel used Fuel save compared electric Charging Fuel Decel Total Fuel to baseline Average Cycle (Litres) (Litres) (Litres) (Litres) 0.01018 fuel save 1 0 0.006125859 0.0007 0.006825859 32.95% 33% 2 0 0.005863396 0.00101 0.006873396 32.48% 3 0 0.005694258 0.00075 0.006444258 36.70% 4 0 0.005926909 0.00087 0.006796909 33.23% 5 0 0.005614755 0.00099 0.006604755 35.12% 6 0 0.006055288 0.00069 0.006745288 33.74% 7 0 0.006553357 0.00074 0.007293357 28.36%

TABLE-US-00010 Test B 10_50_53 Fuel Total Fuel used Fuel save compared electric Charging Fuel Decel Total Fuel to baseline Average Cycle (Litres) (Litres) (Litres) (Litres) 0.01018 fuel save 1 0 0.0058078 0.00116 0.0069678 31.55% 29% 2 0 0.00561421 0.000947 0.00656121 35.55% 3 0 0.00690654 0.000907 0.00781354 23.25% 4 0 0.0063928 0.001013 0.0074058 27.25% 5 0 0.00701493 0.000712 0.00772693 24.10% 6 0 0.00575713 0.001077 0.00683413 32.87% 7 0 0.0065704 0.000904 0.0074744 26.58%

[0238] The first-generation system only had one electric machine directly coupled to the rear wheel through a fixed 10:1 reduction gearbox. The electric machine had the function of discharging as an electric motor from 0-34 km/hr with the energy stored in an ultra-capacitor bank. For Speeds above 30 km/hr and when the voltage of the ultra-capacitor reached a low setpoint of 28V the internal combustion engine was started, and drive was done by the internal combustion engine. In addition, at speeds above 34 km/hr due to the electric machine being directly coupled to the rear wheel it would act as a generator for speeds above 30 km/hr and charge the ultracapacitor. An ultracapacitor pack comprising seventeen 2.7V, 1250 Farad cells in series was used in the vehicle.

[0239] When initially testing on the IDC cycle the energy from the charged ultra-capacitor was used and the electric machine drove the vehicle up to 55 seconds of the 108 second cycle. When a speed greater than 34 km/hr was reached and when the voltage of the ultra-capacitor reached a low setpoint of 28V the petrol motor was started and drove the vehicle while also driving the electric machine to charge the ultracapacitor. By the time the final deceleration is reached in the cycle the petrol motor is turned off as the ultra-capacitor is fully charged back to its original state of 42V.

[0240] This resulted in a 38% fuel save. This was a significant result and unexpected. It was known from previous tests that while in electric drive, due to the efficiency of the electric drive system less energy is used to achieve the same cycle (work) than if the internal combustion engine had been used for drive. What was unexpected was that during charging which occurred from 55 seconds into the IDC drive cycle and completed at 85 seconds in the IDC drive cycle even though the load had increased the fuel used during this period still resulted in an overall fuel save of 38%.

[0241] It was identified that charging had occurred when the ICE was being operated at its optimum brake specific fuel consumption (BSFC) and is also reffered to as the sweet spot. The ICE had sufficient torque to provide drive for the vehicle and also charge the ultra-capacitor in a range of 20-30 Amps so that the full charge was reached by the final deceleration of the IDC cycle.

[0242] Unlike Lithium Ion batteries, the ultra-capacitor was not the component limiting the charging it was the torque capacity of the ICE. A significant discovery was made that if the internal combustion engine is operated at its sweet spot during charging and there is sufficient torque to drive the vehicle and charge, overall a signficant fuel save could be achieved on a cycle

[0243] Further changes to the voltage setpoints for when to start charging produced best results of 42% compared to the baseline on the IDC drive cycle. Active balancing circuitry between individual ultra-capacitor cells was implemented early on to avoid variations in voltage of individual cells which limit current flow in a series set-up. There was also some fuel save due to implementing fuel cut off during deceleration.

[0244] Because the electric machine was directly coupled to the rear wheel it was dependent on the speed of the bike to enable rotation and charging, which was a major negative of the first-generation system.

[0245] It is was identifed that it would be preferable to control the generator rpm and charging through the rpm of the internal combustion engine. This could be achieved by moving the generator to the crankshaft of the engine as opposed to being attached to the rear wheel. This would enable the internal combustion engine to operate at its sweet spot on demand and charge the ultra-capacitor.

[0246] The load on the petrol motor was higher at speeds above 34 km/hr and charging as the petrol motor was driving both the vehicle and the electric machine which was generating electricity to charge the ultracapacitors.

[0247] As the speed increased, the rpm of the electric machine increased causing a higher charging current that put further load on the petrol motor, which ultimately negatively effected drivability performance and could move the ICE out of its sweet spot.

[0248] It was identified that some form of clutch or solenoid switch is preferred in order to disengage the ultra-capacitor load either when the torque demand, or speed of the vehicle is greater than what the internal combustion could achieve at its sweet spot while charging. This would allow the vehicle to operate without a charging load.

[0249] The first-generation system is very sensitive to changes in drive cycle. For example, if customers always drove at speeds below 34 km/hr it would not take long for the energy to be used, then the petrol motor would always be on and no charging would occur as the bike needed to be doing more than 34 km/hr.

[0250] It was identified that it would be preferable to control the generator rpm and charging through the rpm of the internal combustion engine. This could be achieved by moving the generator to the crankshaft of the engine as opposed to being attached to the rear wheel. This would enable the internal combustion engine to operate at its sweet spot on demand more often and charge the Ultra-capacitor more regularly without a reliance on speed of vehicle.

[0251] FIG. 6 shows a configuration of the present invention utilising Electric Drive with the ICE operating the generator. Drive is provide by the electric powertrain with the ICE only connected to the generator to charge the capactivie energy storage, such as an ultra-capacitor. The ICE is run at its sweet spot to charge the ultra-capacitor and maintain sufficient power for the electric powertrain as described in the invention.

[0252] FIG. 7 shows a configuration of the present invention with the ICE using mechanical drive and Electric Power Assist. In this configuration, the electric machine is connected to the crankshaft. The ICE can drive the vehicle through the transmission to the wheel. The electric machine can provide power assist to the ICE when there is sufficient charge in the ultra-capacitor to maintain its operation at the sweet spot. The electric machine can also charge the ultra-capacitor on demand as described in Invention.

[0253] FIG. 8 shows the ICE with mechanical drive, electric drive and Electric Power Assist. In this configuration, the electric machines can be connected to the crankshaft as wheel as drive wheels. The ICE can drive the vehicle through the transmission to the wheel. The electric machine/s can provide power assist to the ICE when there is sufficient charge in the ultra-capacitor to maintain its operation at the sweet spot. The electric machine can also charge the ultra-capacitor on demand as described in the invention. Additionally pure electric drive is available when the ultra-capacitor has sufficient charge.

EMBODIMENTS

[0254] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases in one embodiment or in an embodiment in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0255] Similarly, it should be appreciated that in the above description of example embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description of Specific Embodiments are hereby expressly incorporated into this Detailed Description of Specific Embodiments, with each claim standing on its own as a separate embodiment of this invention.

[0256] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0257] Different Instances of Objects

[0258] As used herein, unless otherwise specified the use of the ordinal adjectives first, second, third, etc., to describe a common object, merely indicate that different instances of like objects are being referred to and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

[0259] Specific Details: In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0260] Terminology: In describing the preferred embodiment of the invention illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as forward, rearward, radially, peripherally, upwardly, downwardly, and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms.

[0261] Comprising and Including: In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word comprise or variations such as comprises or comprising are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

[0262] Any one of the terms: including or which includes or that includes as used herein is also an open term that also means including at least the elements/features that follow the term, but not excluding others. Thus, including is synonymous with and means comprising.

[0263] Scope of Invention: Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as fall within the scope of the invention. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present invention.

[0264] Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

INDUSTRIAL APPLICABILITY

[0265] It is apparent from the above, that the arrangements described are applicable to a system and apparatus for the motoring and vehicle industry.