GB2528264A

GB2528264A - An optimum hybrid vehicle

Info

Publication number: GB2528264A
Application number: GB1412516.5A
Authority: GB
Inventors: Othman Bin Ahmad
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-07-15
Filing date: 2014-07-15
Publication date: 2016-01-20
Also published as: GB201412516D0

Abstract

The present invention relates to an optimum hybrid vehicle 100, characterized by: an internal combustion engine 1; a main transmission 2; a motor 4 connected to the internal combustion engine 1 by means of an auxiliary transmission 5; a crankshaft pulley clutch 6; a motor transmission 7; a power storage 10; an air-conditioning compressor 8 connected to the internal combustion engine 1; and an air-conditioning clutch 9 connecting the air-conditioning compressor 8 and the auxiliary transmission 5. The present invention provides a new power system for hybrid vehicles, with simple structure, lower cost, optimum energy consumption and less exhaust gas emissions and yet can be fitted easily to all existing vehicles that use internal combustion engines connected with all types of transmission.

Description

Intellectual Property Office Application No. GB1412516.5 RTM Date:20 January 2015 The following terms are registered trade marks and should be read as such wherever they occur in this document: Honda Integrated Motor Assist IMA Mercedes Benz General Toyota Ford Escape Ford Chevrolet Volt Mazda Intellectual Property Office is an operating name of the Patent Office www.ipo.govuk

AN OPTIMUM HYBRID VEHICLE

Background of the luvention

Field of the Invention

This invention relates to a hybrid vehicle system of a combined driving unit fed with fuel and electric power, aM more particularly to a power system of a hybrid vehicle having a single motor/generator.

Description of Related Arts

Hybrid vehicles developed by various vehicle manufacturers in Japan and United States of America, are at the fore front in the environmental protection by optimising the use of energy in vehicles. Hybrid vehicles provide efficient mode of transporting people whfle providing individual freedom in choosing their destinations, Hybrid vehicles can also be used in types of vehicles such as cars, lorries and busses which will still be important IS components of the transportation industry in the foreseeable future.

Power systems for hybrid vehicles come in various types but can be divided into two maj or types, i.e. series arrangement ad parallel arrangement. Generally, various variations of these two major types are possible, wherein each having its own advantages and disadvantages. Honda Corporation for example uses the Integrated Motor Assist (IIVIA) mid-parallel hybrid arrangement in their hybrid cars similar to Mercedes Benz, B\4W and General Motors BAS hybrid vehicle collections. The Toyota Corp on the other hand uses the Hybrid Synergy Drive series-parallel hybrid arrangement in its hybrid cars while other manufacturers using series-parallel hybrid arrangements are the Ford Escape and Ford Fusio; whereas General Motors Chevrolet Volt uses the series-hybrid arrangement.

The Toyota Corp Hybrid Synergy Drive has multiple driving modes and a large electric motor with complicated connection systems and therefore high manufacturing cost. In order to maximise the utilisation of the larger motor, a large batten' is used to allow the vehicle to be driven electrically to a reasonable distance. The IMA system of the Honda Hybrid cars has simpler connections so it has lower manufacturing cost but it has less driving modes, smaller electric power component, less efficiency driving through the combustion engine arid therefore more fuel consumption arid exhaust gas emission than the Hybrid Synergy Drive. The series-hybrid car such as the Chevrolet Volt uses a large electric motor with only a small internal combustion engine and thus much larger battery.

It is extremely efficient as it uses electric power most of the time, with the internal combustion engine primarily used as a range extender.

Prior art of US patent no. 7,343,993 B2 by China First Automobile Group Corporation, uses a dual-motor solution to the series-parallel hybrid, allowing a simpler connection to the drive shafts, Although using simpler connections, a large battery is still required to utilise the large main motor, and the main motor requires custom connection to the drive shaft. The Ferari Hybrid vehicle, of US patent application no. US 201 P008393916 M, also uses a dual-motor solution in order to allow cheaper conversion of existing internal combustion engine designs but its auxiliary motor is used only to drive the auxiliary devices such as air-conditioning compressor and cannot even start the internal combustion engine, unlike the hybrid vehicle by the China First Automobile Group Corporation.

However, the dual-motor hybrid vehicles should only reduce conversion cost of existing designs but not existing vehicles since the motor need to be connected to the transmission systems of vehicles. In addition to that, the dual-motor hybrid vehicles also use large batteries.

Although the power systems for hybrid vehicles in the prior arts have high energy efficiency these power systems have a number of limitations, They require connection of electric motor to the drive shafts in order to power the vehicle which will require an expensive modification to existing vehicles thus increasing costs. Since a large main motor is involved, a large battery is also required to power the vehicle and increases the usage of the electrical power mode in order to justify the installation of the larger motor, It is known that a large battery does not have a long life and replacing it is very costly and hence negating the saving in fuel consumption.

These dual-motor hybrid vehicles should reduce conversion cost of existing designs but not existing vehicles since the motor need to be connected to the transmission systems of vehicles, They also use large batteries. The Mazda i-ELOOP system, on the other hand uses a small battery since it uses the energy from the brake recovery to power electrical devices only but it means that it cannot fully utilise the kinetic energy recovered by the brake energy recovery system.

Patent no. 1)5 7,559,388 B2 attempts to optimise the operating efficiency of the internal combustion engine by operating it only at its maximum conditions of high efficiency which is more than 30% of the engine's maximum torque output. This means that the electric motor needs to provide power up to 30% of the total designed total power output which is somewhere in between the 20% for Honda's IMA and 50% for Toyota's Synergy drive.

Accordingly, it can be seen in the prior arts that there exists a need to provide a power system of a hybrid vehicle to overcome the limitations of these dual-motor system for use in the hybrid vehicle system without involving high cost of modification as well as providing the smallest battery that can fully utilise the recovered kinetic energy of the hybrid vehicle.

Summary of Invention

It is an objective of the present invention to provide a hybrid power system to allow any existing internal combustion vehicles with various transmission types to be modified in order to take advantage of a hybrid vehicle system.

It is also an objective of the present invention to provide a hybrid power system to allow any existing internal combustion vehicles with various transmission types to be modified with minimal modification to reduce the cost of design and modification.

Another objective of the present invention is to optimise the cost of running a hybrid system in all aspects of savings by reducing the requirement for large batteries but just sufficiently large enough to take advantage of the kinetic energy recovered during braking to be fully used for powering the air-conditioning system.

Accordingly, these objectives may be achieved by following the teachings of the present invention. The present invention relates to an optimum hybrid vehicle, characterized by: an internal combustion engine; a main transmission; a motor connected to the internal combustion engine by means of an auxiliary transmission; a crankshaft pulley clutch; a motor transmission; a power storage; an air-conditioning compressor connected to the internal combustion engine; and an air-conditioning clutch connecting the air-conditioning compressor and the auxiliary transmission. The present invention provides a new power system for hybrid vehicles, with simple structure, lower cost, optimum energy consumption and less exhaust gas emissions and yet can be fitted easily to all existing vehicles that use internal combustion engines connected with all types of transmission,

Brief Description of the Drawings

The features of the invention will be more readily understood and appreciated from the following detailed description when read in conjunction with the accompanying drawings of the preferred embodiment of the present invention, in which: Fig, I is a diagram showing a preferred embodiment of a simplified optimum hybrid vehicle.

Fig. 2 is a diagram showing a preferred embodiment of a more detailed view of the optimum hybrid vehicle.

Fig. 3a to 3h are diagrams showing a preferred embodiment of power flows for various modes of the optimum hybrid vehicle.

Detailed Description of the Invention

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting but merely as a basis for claims. It should be understood that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the

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invention is to cover all modifications, equivalents and alternatives falling within the scope of the present invention as defined by the appended claims. As used throughout this application, the word "may" is used in a pennissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words "include," "including," and "includes" mean including, but not limited to. Further, the words "a" or "an" mean "at least one" and the word "plurality" means one or more, unless otherwise mentioned, Where the abbreviations or technical terms are used, these indicate the commonly accepted meanings as known in the technical field, For ease of reference, common reference numerals will be used throughout the figures when referring to the same or similar features common to the figures. The present invention will now be described with reference to Figs. I-3h.

Referring to fig. 1, the present invention relates to an optimum hybrid vehicle (100), characterized by: an internal combustion engine (1) for propulsion in a normal driving mode; a main transmission (2) comprising gearing arrangement of the optimum hybrid vehicle (100) connected to the internal combustion engine (1) by means of a clutch (3); a motor (4) connected to the internal combustion engine (1) by means of an auxiliary transmission (5) to crank the internal combustion engine (1); a crankshaft pulley clutch (6) connected between the internal combustion engine (I) and the auxiliary transmission (5); a motor transmission (7) connected between the motor (4) and the auxiliary transmission (5); a power storage (10) electrically connected to the motor (4) for storing electrical power generated by the motor (4); an air-conditioning compressor (8) connected to the internal combustion engine (I) by means of the auxiliary transmission (5); and an air-conditioning clutch (9) connecting the air-conditioning compressor (8) and the auxiliary transmission (5).

As shown in Fig. 1, the optimum hybrid vehicle (100) is an improvement of a dual-motor power system for a hybrid vehicle as disclosed in the US patent no, 7,343,993 B2.

Advantageously, the present invention only utilizes one motor that drives the optimum hybrid vehicle (100) through the crankshaft pulley clutch (6).

In the preferred embodiment of the present invention as shown in Fig. 1, the motor (4) may be connected to a crankshaft of the internal combustion engine (I) via the auxiliary transmission (5). In a preferred embodiment of the optimum hybrid vehicle (100), the auxiliary transmission (5) comprises of shafts, belts, pulleys, chains, gears, clutches or any combination thereof. The crankshaft pulley clutch (6) may be arranged between the auxiliary transmission (5) and the internal combustion engine (1). Therefore, when the motor (4) is not running, the motor (4) can be disconnected from the internal combustion engine (1) and the main transmission (2) in order to reduce energy consumption. In a preferred embodiment of the optimum hybrid vehicle (100), the crankshaft pulley clutch (6) is a magnetic, mechanical or fluid clutch.

The air-conditioning compressor (8) may also be connected to the crankshaft of the internal combustion engine (I) via the auxiliary transmission (5). An air-conditioning clutch (9) may be arranged between the air-conditioning compressor (8) and the internal combustion engine (1). Therefore, when the air-conditioning compressor (8) is not required, the air-conditioning compressor (8) can be disconnected from the internal combustion engine (1). Thus, less energy will be consumed and less load will be exerted to the motor (4) to turn the crankshaft of the internal combustion engine (1). The motor (4) may also be connected to the auxiliary transmission (5) via the motor transmission (7), In a preferred embodiment of the optimum hybrid vehide (100), the motor (4) has a mode that turns it into a generator to generate electrical power. In the preferred embodiment, the motor (4) is changed from a motor mode to a generator mode during braking. When the power level of the power storage (10) is deemed low, a motor controller (21) changes the motor (4) into the generator mode, either when the main transmission (2) gearing arrangement is at neutral position or during the normal driving mode when the main transmission (2) is engaged, in order to charge the power storage (10) to a full state of charging. In a preferred embodiment, it is not necessary to frilly charge the power storage (10) to reduce energy consumption. Remaining of the power storage (10) is preferably be recharged by regenerative braking through a braking energy recovery mode, lii another preferred embodiment, states of charging for the power storage ( 0) may be varied according to user inputs or conditions of the power storage (10) components. In the preferred embodiment, the power storage (10) stores electrical power generated by the motor (4) in the generator mode via high voltage motor circuit (16) to the motor controller (21), and via high voltage direct current (DC) circuit (9) to a distribution unit (20) and then to a direct current to direct current (DC/DC) converter (18) via the high voltage DC circuit (9).

Generally, the amount of possible kinetic energy stored during the braking energy recovery mode is not very high. An example of a compact car with a mass of 1000 kg, and an average cruising speed of 76 1cm/hour is only 200 kJ extra energy for a 40 AR battery.

However in the preferred embodiment, extra power storage capacity of twice its kinetic energy recovered i.e. 400kJ extra for a normally 40 AH battery is preferred in order to maximize the utilization of the regenerative braking of the optimum hybrid vehicle (100).

In one embodiment of the present invention, in order to provide enough power to restart the internal combustion engine (1) while accelerating the optimum hybrid vehicle (100) at a preferred rate of lOs to 100 km/hr simultaneously, the maximum power of the motor (4) should roughly be 7.5 kW. This means that it requires a battery ofat least 17 C i.e. 17 times the 40 in the 40 AH battery capacity rating, of amperes of discharging current, This amount of discharge current is too high for a normal lead acid battery. In a preferred embodiment of the optimum hybrid vehicle (100), the power storage (10) is a high capacity and high discharge electrical storage devices. In a preferred embodiment of the optimum hybrid vehicle (100), the power storage (10) comprises a Lithium Polymer (LiPo) battery or Supercapacitor or combination of a battery and Supercapacitor.

In another preferred embodiment, the motor (4) should also be able to drive the air-conditioning compressor (8) during a start up but not necessarily at the same time. The present invention preferably uses only around 10% electric power compared to the other prior art, which are 20% for Honda, 30% for Severinsky and 50% for Toyota.

The power storage (10) is connected to the backup starter (29) and DC/DC converter (18) using the low voltage circuit (17). h an alternative embodiment of the optimum hybrid vehicle (100), the power storage (10) is a high voltage LiPo battery so a DC/DC down converter is required to connect it to the backup starter (29) via the low voltage circuit (17).

In the preferred embodiment, LiPo battery provides a higher capacity for similar weight of a normal lead acid battery. LiPo battery also provides higher discharge current. However, it is subject to sudden overheating and is therefore vital that the power storage (10) is preferably put inside a protective inflammable and heat resistant case inside the optimum hybrid vehicle (100). In another preferred embodiment, the small size of the LiPo battery allows it to fit into a normal power storage (10) compartment. On top of that, the higher capacity of the LiPo battery allows the optimum hybrid vehicle (100) to operate longer in an air-conditioning idling stop mode and thus improves fuel economy while increasing comfort to the user.

In the preferred embodiment of the present invention as shown in Fig. 2, the motor controller (21), a transmission controller (28), a main controller (25) and a battery controller (26) are electronic devices of the optimum hybrid vehicle (100) used for energy-management and transmission control which are all interconnected by the signal circuit (31). On the other hand, a transmission switch (27), an ignition switch (22), a brake pedal (23), an accelerator pedal (23) and signal circuit (31) are devices for conveying inputs from the user.

In a preferred embodiment, a pair of front wheels (11) coupled by a front drive shaft (12), and a pair of rear wheels (13) coupled by a rear drive shaft (14) and a rear axle (15) are used for mobility of the optimum hybrid vehicle (100).

The present invention also provides a method of operation for an optimum hybrid vehicle (100), comprising the steps of: performing normal starting mode when the optimum hybrid vehicle (100) is stationary and a main transmission (2) gearing arrangement is at neutral; performing normal driving mode by running an internal combustion engine (I) to drive the optimum hybrid vehicle (100) independently; performing full-accelerating mode by running both the internal combustion engine () and a motor (4) to drive the optimum hybrid vehicle (100); performing braking energy recovery mode by generating electrical power for charging a power storage (10) when the motor (4) is controlled for slowing down the optimum hybrid vehicle (100); performing electrical air-conditioning idling mode when the internal combustion engine (1) stops running and an air-conditioning compressor (8) is powered by the motor (4); and performing restarting mode by running the motor (4) to an idling revolution, then engaging a crankshaft pulley clutch (6) of the internal combustion engine (1) to rotate the internal combustion engine (1) until it reaches a predetermined rotation rate for the optimum hybrid vehicle (100) to perform the normal driving mode.

In the preferred embodiment, the main controller (25) in the present invention controls the power system of the optimum hybrid vehicle (100), in accordance with the modes in the method of operation for an optimum hybrid vehicle (100) which are schematically illustrated herein with reference to Fig. 3a -3h.

As shown in Fig. 3a is preferably a pre-starting mode of the optimum hybrid vehicle (100), After the ignition switch (22) is turned on, the main controller (25) will firstly check the status of energy consumption, the power storage (10) level and input received from the user of the optimum hybrid vehicle (100). Then, after the pre-starting mode, the optimum hybrid vehicle (100) will be in the normal starting mode.

Fig. 3b shows the normal starting mode of the optimum hybrid vehicle (100). In the normal starting mode, the transmission switch (27) may be set automatically to a neutral gearing arrangement, or warning indicator is switched on for manual intervention to set to the neutral gearing arrangement. The motor (4) preferably has sufficient power for the initial start. Therefore, if the power storage (10) condition is below the recharging state of charge level, the air-conditioning clutch (9) and crankshaft pulley clutch (13) are then disengaged to reduce the starting load, The main controller (25) receives a starting signal and sends the starting signal via the motor controller (21) to turn on the motor (4) with support from a backup starter (29). Electric power is drawn from the power storage (10) to be transmitted to the motor (4) via a distribution unit (20) and the motor controller (21) to run the motor (4). The optimum hybrid vehicle (100) is then changed to an idling stop mode. When battery condition is normal (above recharging state of charge level), vehicle mode is changed to electrical air-conditioning idling mode.

In the idling stop mode as shown in Fig. 3d, the speedometer of the optimum hybrid vehicle (100) indicates zero reading and the internal combustion engine (1) is running.

When the accelerator pedal (24) is not pressed, the main controller (25) checks whether the power storage (10) has already reached above the recharging state of charge level. If the power storage is still below the recharging state of charge level, the internal combustion engine (1) stays in the idling stop mode, where the internal combustion engine (1) runs and the motor (4) charges the power storage (10). In the idling stop mode, the air-conditioning compressor (8) is preferably enabled based on user sefting, until the power storage (10) is above recharging state of charge level or the idling stop mode is changed to other modes by the user such as when applying the accelerator pedal (24).

Otherwise, if the power storage (10) state increased above the recharging state of charge level, the main controller (25) then sends a signal to the internal combustion engine controller (30) to stop the internal combustion engine (1) and then enters into the electrical air-conditioning idling mode. Fig, 3f shows the electrical air-conditioning idling mode of the optimum hybrid vehicle (100). In the electrical air-conditioning idling mode, the crankshaft pulley clutch (6) is disengaged and the air-conditioning clutch (9) is engaged to allow the motor (4) to run the air-conditioning compressor (8). If the power level of the power storage (10) is getting low again, the electrical air-conditioning idling mode is changed back to the idling stop mode, However, if the accelerator pedal (24) is applied, the electrical air-conditioning idling mode is changed to the restarting mode.

When the accelerator pedal (24) is applied in the restarting mode of the optimum hybrid vehicle (100), the main controller (25) then checks the status of the main transmission (2).

If the main transmission (2) gearing arrangement is at neutral, the optimum hybrid vehicle

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(100) shall change to the normal starting mode and then the main transmission (2) gearing arrangement is changed to a driving gearing transmission of the optimum hybrid vehicle (100). Then the normal starting mode shall change to the normal driving mode.

When the optimum hybrid vehicle (100) is in the restarting mode and the main transmission (2) gearing arrangement is not at neutral, the main controller (25) will check if the optimum hybrid vehicle (100) satisfies the conditions of: the motor (4) is preferably able to provide torque to turn the internal combustion engine (1) to around 800 rpm at an idling revolution of the internal combustion engine (1) when assisted by the backup starter (15); and the crankshaft pulley dutch (6) is preferably able to handle and provide torque to move the optimum hybrid vehicle (100); and the backup-starter (15) is preferably available (25) to assist the restarting mode.

In the preferred embodiment, if said conditions of the optimum hybridvehicle00) when the main transmission (2) gearing arrangement is not at neutral are satisfied, then the air-conditioning clutch (9) and the crankshaft pulley clutch (6) are disengaged first in order to reduce the starting load. The main controller (25) receives a starting signal and sends the starting signal via the motor controller (21) to turn on the motor (4) with assistant from a backup starter (29). Electric power is drawn from the power storage (10) and transmitted to the motor (4) via a distribution unit (20) and the motor controller (2]) to run the motor (4), When the motor (4) reaches the idling revolution of around 800 rpm, the crankshaft pulley clutch (6) is slowly engaged followed by the backup starter (29). The optimum hybrid vehicle (100) will then move slowly while the crankshaft of the internal combustion engine (1) is rotated until the rotation rate of the internal combustion engine (1) reaches an ideal rotation rate for starting of around 800 rpm which is preferably occurring when the optimum hybrid vehicle (100) speed is around 10 km/hr. Then the internal combustion engine (]) is started, as shown in Fig. 3c, The restarting mode is then changed to the normal driving mode.

In another preferred embodiment, if the main transmission (2) gearing arrangement is not at neutral position, and said conditions are not met, the optimum hybrid vehicle (100) is preferably applying the steps of changing the transmission switch (18) to the neutral gearing arrangement; using the normal starting mode to start the internal combustion engine (1) and then revert to previous transmission state before the accelerator pedal (24) is applied; arid changing the normal starting mode to the normal driving mode once the speedometer reaches a specified speed of around 10 km/br, i.e. the internal combustion engine (1) reaches an ideal rotation rate for starting of around 800 rpm.

In the normal driving mode of the optimum hybrid vehicle (100), the internal combustion engine (1) runs in an optimum efficiency operating region when the accelerator pedal (24) is applied. In a preferred embodiment, the output power from the internal combustion engine (1) is used to drive the optimum hybrid vehicle (100) as well as driving the motor (4) in the generator mode simultaneously, so as to recharge the power storage (10) when the power storage (10) level is low while the air-conditioning compressor (8) is activated.

Shown in Fig. 3e is the internal combustion engine (1) independently driving the optimum hybrid vehicle (100) in the normal driving mode. When the power storage (10) level is full, the motor transmission (7) is disengaged.

In a preferred embodiment of the method of operation for a optimum hybrid vehicle (100), the full-accelerating mode is performed when an accelerator pedal (24) is applied completely or promptly. In the full-accelerating mode as shown in Fig. 3c, the accelerator pedal (24) is applied to accelerate the optimum hybrid vehicle (100). If the power level of the power storage (10) is above the recharging state of charge level, both the power from the internal combustion engine () and the motor (4) are used at a maximum level which will be combined together at an output shaft of the main transmission (2) to drive the optimum hybrid vehicle (100). In another embodiment, the motor transmission (7) may also be set to use a continuously variable transmission, or adjusting output voltage of the motor controller (TI) and the motor (4) or disengaging the air-conditioning clutch (9) to enable the optimum hybrid vehicle (100) to operate at the higher speed in the full-accelerating mode. j

In a preferred embodiment of the method of operation for an optimum hybrid vehicle (100), the braking energy recovery mode is performed when a brake pedal (23) is applied. In the in braking energy recovery mode of the optimum hybrid vehicle (100) as shown in Fig, 3g, the brake pedal (23) is stepped down to decelerate the optimum hybrid vehicle (100). A brake signal is transmitted to the main controller (25) by the brake pedal (23). The main controller (25) calculates brake torque of the motor (4) in accordance with the speed of the optimum hybrid vehicle (100), and sends a signal to the motor controller (2t), which controls the motor (4) to brake and generate electrical power from the regenerative braking.

The generated electrical power is then used to recharge the power storage (10).

After the braking energy recovery mode and the speedometer indicates non-zero reading while the internal combustion engine (1) is in idling status, the optimum hybrid vehicle (100) enters the normal idling mode. When the power storage (10) level is low in the normal idling mode and the accelerator pedal (24) is not pressed, the air-conditioning clutch (9) and the crankshaft pulley clutch (13) are engaged. The motor mode of the motor (4) is changed to the generator mode for charging the battery system (8) as shown in Fig. 3d. When the power storage (10) level is in the full state of charge level, charging is stopped and the motor (4) is disengaged as shown in Fig. 3h.

In an alternative embodiment, the internal combustion engine (1) may be stopped and the crankshaft pulley clutch (6) is disengaged, while the normal idling mode is changed to electrical air-conditioning idling mode. However, this is not preferred because in the normal idling mode, the optimum hybrid vehicle (100) should be able to power the air-conditioning compressor (8) easily without resorting to the power storage (10) which may drain the power storage (10) unnecessarily.

The present invention also provides a method of designing an optimum hybrid vehicle (100), comprising the steps of: designing a motor (4) that provides sufficient power to move the optimum hybrid vehicle (100) at the lowest main transmission (2) gearing arrangement, and at the idle revolution of an internal combustion engine (1); designing a power storage (10) with capacity to allow additional energy stored equivalent to at least twice of the kinetic energy recovered during braking energy recovery mode of the optimum hybrid vehicle (100) at an average cruising speed; designing the power storage (10) such that discharge rate of the power storage (10) is able to provide electrical power to the motor (4) to restart and allow the internal combustion engine (1) to run up to an idling revolution or powering the air-conditioning compressor (8); and designing an auxiliary transmission (5) such that power from the motor (4) is transferred to the internal combustion engine (1) via its crankshaft pulley clutch (6).

Accordingly, the present invention provides advantages in allowing all types of transmissions to be used while providing energy conservation through the braking energy recovery mode and the idling stop mode. Wherein in the braking energy recovery mode, the internal combustion engine (1) stops using fuel although its crankshaft turns and runs the motor (4) via the crankshaft pulley clutch (6) and the auxiliary transmission (5) in the generator mode to store electrical energy via the power storage (10) while the electrical energy recovered is used to power the air-conditioning compressor (8) when required, as well as the other auxiliary devices such as water pump that are connected via the auxiliary transmission (5) or other electrical systems such as lights.

An alternative embodiment is to use cheaper Lead acid battery in parallel with Supercapacitors. Supercapacitors have higher current discharge rate but are expensive for the battery capacity it can provide, at present.

Another alternative embodiment is to operate without the crankshaft pufley clutch (6) provided the motor (4) has sufficient power to turn the internal combustion engine (1) with main transmission (2) set to neutral and air-conditioning compressor (8), during the electrical air-conditioning idling mode. This should not pose any problem because of the requirement that the motor (4) should be able to move the vehicle up to the idling speed, but it will mean large energy losses in overcoming engine friction.

Yet another alternative embodiment is to use separate motor md generator instead of the preferred embodiment of a dual mode motor (4), The electrical circuitry will be simpler but the design will be heavier and will require more space in the engine compartment.

Although the present invention has been described with reference to specific embodiments, also shown in the appended figures, it will be apparent for those skilled in the art that many variations aiid modifications ca be done within the scope of the invention as described in the specification and defined in the following claims.

Description of the reference numerals used in the accompanying drawings according to the present invention: Reference

Description

Numerals optimum hybrid vehicle 1 internal combustion engine 2 main transmission 3 clutch 4 motor auxiliary transmission 6 crankshaft pulley clutch 7 motor transmission 8 air-conditioning compressor 9 air-conditioning clutch power storage 11 front wheel 12 front drive shaft 13 rear wheel 14 rear drive shaft rear axle 16 high voltage motor circuit 17 low voltage circuit 18 DC/DC converter 19 high voltage DC circuit distribution unit 21 motor controller 22 ignition switch 23 brake pedal 24 accelerator pedal main controller 26 battery controller 27 transmission switch 28 transmission controller 29 backup starter internal combustion engine controller 31 signal circuit