Power transmitting apparatus and method of controlling the same

• US 5,789,877 A
• Filed: 04/22/1996
• Issued: 08/04/1998
• Est. Priority Date: 05/19/1995
• Status: Expired due to Term

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Yamada, Eiji, Kanamori, Akihiko, Kawabata, Yasutomo, Mizutani, Ryouji, Miyatani, Takao
• Primary Examiner(s): Cabeca, John W.
• Application Number:
  US08/635,661
• Time in Patent Office: 834 Days
• Field of Search: 318/9, 318/11, 318/396, 318/379, 318/381, 318/995, 318/366, 318/49, 318/478, 318/78-79, 318/76, 318/87, 318/432-434, 477/5, 477/7, 477/15, 477/20, 477/30, 60/39.06, 364/424.1, 364/424.026, 364/426.01, 364/431.051, 74/845, 74/730, 74/61, 74/655 A, 180/65.1-65.4, 123/205, 123/338, 123/357
• US Class Current: 318/9
• CPC Class Codes: B60K 17/356 having fluid or electric motor, for driving one or more wheels disposition of motor in, or adjacent to, traction wheel B60K7/00
• CPC Class Codes: B60K 2006/262 the motor or generator are used as clutch, e.g. between engine and driveshaft
• CPC Class Codes: B60K 23/0808 for varying torque distribution between driven axles, e.g. by transfer clutch
• CPC Class Codes: B60K 6/22 characterised by apparatus, components or means specially adapted for HEVs
• CPC Class Codes: B60K 6/26 characterised by the motors or the generators
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/40 characterised by the assembly or relative disposition of components
• CPC Class Codes: B60K 6/448 Electrical distribution type
• CPC Class Codes: B60K 6/52 Driving a plurality of drive axles, e.g. four-wheel drive
• CPC Class Codes: B60L 2220/52 Clutch motors
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60L 2260/28 Four wheel or all wheel drive
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60L 7/003 Dynamic electric braking by short circuiting the motor
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/26 : for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 20/00 : Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/30 : Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: B60W 2510/244 : Charge state
• CPC Class Codes: B60W 2710/0644 : Engine speed
• CPC Class Codes: B60W 2710/0666 : Engine torque
• CPC Class Codes: B60W 2710/081 : Speed
• CPC Class Codes: B60W 2710/083 : Torque
• CPC Class Codes: B60W 2710/105 : Output torque
• CPC Class Codes: B60W 2710/1061 : Output power
• CPC Class Codes: B60W 30/18018 : Start-stop drive, e.g. in a traffic jam
• CPC Class Codes: H02K 51/00 : Dynamo-electric gears, i.e. dynamo-electric means for transmitting mechanical power from a driving shaft to a driven shaft and comprising structurally interrelated motor and generator parts
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y10S 903/903 : having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/906 : Motor or generator
• CPC Class Codes: Y10S 903/91 : Orbital, e.g. planetary gears
• CPC Class Codes: Y10S 903/916 : with plurality of drive axles
• CPC Class Codes: Y10S 903/947 : Characterized by control of braking, e.g. blending of regeneration, friction braking
• CPC Class Codes: Y10S 903/951 : Assembly or relative location of components

Abstract

A power transmitting apparatus (20) attached to a crankshaft (56) of an engine (50) includes a clutch motor (30), an assist motor (40), and a controller (80) for controlling the clutch motor (30) and the assist motor (40). When detecting an ignition switch in a starter position, the controller (80) makes a constant current flow through three-phase coils (44) of the assist motor (40) to fix a drive shaft (22) and makes a current flow through three-phase coils (36) of the clutch motor (30) to enable the clutch motor (30) to apply a starter torque TST to the crankshaft (56). This results in cranking the crankshaft (56). Concurrently with the cranking process, fuel injection into the engine (50) and spark ignition are controlled to start the engine (50).

Claims

1. A power transmitting apparatus for starting an engine and transmitting power output from said engine to a drive shaft, said power transmitting apparatus comprising:

a clutch motor comprising a first rotor connected with an output shaft of said engine and a second rotor connected with said drive shaft, said second rotor being coaxial to and rotatable relative to said first rotor, said first and second rotors being electromagnetically connected with each other to transmit power between said output shaft of said engine and said drive shaft via the electromagnetic connection of said first and second rotors;

a clutch motor-driving circuit for controlling a degree of the electromagnetic connection of said first and second rotors of said clutch motor and regulating rotation of said second rotor relative to said first rotor;

an assist motor connected with said drive shaft;

an assist motor-driving circuit for driving and controlling said assist motor;

a storage battery being charged with power regenerated by said clutch motor via said clutch motor-driving circuit, being charged with power regenerated by said assist motor via said assist motor-driving circuit, discharging power required to drive said clutch motor via said clutch motor-driving circuit, and discharging power required to drive said assist motor via said assist motor-driving circuit;

starter position detecting means for detecting an ignition switch in a starter position;

starter control means for, when said starter position detecting means detects said ignition switch in said starter position, setting said drive shaft into a locking state and controlling said clutch motor-driving circuit to allow said clutch motor to crank said output shaft of said engine with the power stored in said storage battery; and

engine operation control means for injecting a fuel into said engine and igniting a spark in said engine concurrently with the cranking operation by said starter control means.

2. A power transmitting apparatus in accordance with claim 1, wherein said starter control means comprises means for setting said drive shaft into the locking state by locking up said assist motor with the power stored in said storage battery.

3. A power transmitting apparatus in accordance with claim 1, wherein said starter control means comprises means for utilizing the power stored in said storage battery to make said assist motor output a torque, which is substantially equivalent to a torque applied from said clutch motor to said output shaft of said engine, to said drive shaft concomitantly by the cranking operation, thereby setting said drive shaft into the locking state.

4. A power transmitting apparatus for starting an engine and transmitting power output from said engine to a drive shaft, said power transmitting apparatus comprising:

a complex motor comprising a first rotor connected with an output shaft of said engine, a second rotor connected with said drive shaft being coaxial to and rotatable relative to said first rotor, and a stator for rotating said second rotor, said first rotor and said second rotor constituting a first motor, said second rotor and said stator constituting a second motor;

a first motor-driving circuit for driving and controlling said first motor in said complex motor;

a second motor-driving circuit for driving and controlling said second motor in said complex motor;

a storage battery being charged with power regenerated by said first motor via said first motor-driving circuit, being charged with power regenerated by said second motor via said second motor-driving circuit, discharging power required to drive said first motor via said first motor-driving circuit, and discharging power required to drive said second motor via said second motor-driving circuit;

starter position detecting means for detecting an ignition switch in a starter position;

starter control means for, when said starter position detecting means detects said ignition switch in said starter position, setting said drive shaft into a locking state and controlling said first motor-driving circuit to allow said first motor to crank said output shaft of said engine with the power stored in said storage battery; and

engine operation control means for injecting a fuel into said engine and igniting a spark in said engine concurrently with the cranking operation by said starter control means.

5. A power transmitting apparatus for starting an engine and transmitting power output from said engine to a drive shaft, said power transmitting apparatus comprising:

a clutch motor comprising a first rotor connected with an output shaft of said engine and a second rotor connected with said drive shaft, said second rotor being coaxial to and rotatable relative to said first rotor, said first and second rotors being electromagnetically connected with each other to transmit power between said output shaft of said engine and said drive shaft via the electromagnetic connection of said first and second rotors;

a clutch motor-driving circuit for controlling a degree of the electromagnetic connection of said first and second rotors of said clutch motor and regulating rotation of said second rotor relative to said first rotor;

an assist motor connected with said drive shaft;

an assist motor-driving circuit for driving and controlling said assist motor;

a storage battery being charged with power regenerated by said clutch motor via said clutch motor-driving circuit, being charged with power regenerated by said assist motor via said assist motor-driving circuit, discharging power required to drive said clutch motor via said clutch motor-driving circuit, and discharging power required to drive said assist motor via said assist motor-driving circuit;

a clutch mounted on said drive shaft to receive an output of said assist motor, said clutch connecting and disconnecting transmission of the output;

starter position detecting means for detecting an ignition switch in a starter position;

cranking control means for, when said starter position detecting means detects said ignition switch in said starter position, releasing the connection of said clutch, controlling said assist motor-driving circuit to enable said assist motor to output a torque to said drive shaft with the power stored in said storage battery, and controlling said clutch motor-driving circuit to enable said clutch motor to transmit the torque, which is output from said assist motor to said drive shaft, to said output shaft of said engine and thereby cranking said output shaft of said engine; and

engine operation control means for injecting a fuel into said engine and igniting a spark in said engine concurrently with the cranking operation by said cranking control means.

6. A power transmitting apparatus in accordance with claim 5, wherein said cranking control means comprises means for locking up said clutch motor to transmit the torque output from said assist motor to said output shaft of said engine.

7. A power transmitting apparatus for starting an engine and transmitting power output from said engine to a drive shaft, said power transmitting apparatus comprising;

a complex motor comprising a first rotor connected with an output shaft of said engine, a second rotor connected with said drive shaft being coaxial to and rotatable relative to said first rotor, and a stator for rotating said second rotor, said first rotor and said second rotor constituting a first motor, said second rotor and said stator constituting a second motor;

a first motor-driving circuit for driving and controlling said first motor in said complex motor;

a second motor-driving circuit for driving and controlling said second motor in said complex motor;

a storage battery being charged with power regenerated by said first motor via said first motor-driving circuit, being charged with power regenerated by said second motor via said second motor-driving circuit, discharging power required to drive said first motor via said first motor-driving circuit, and discharging power required to drive said second motor via said second motor-driving circuit;

a clutch mounted on said drive shaft to receive an output of said complex motor, said clutch connecting and disconnecting transmission of the output;

starter position detecting means for detecting an ignition switch in a starter position;

cranking control means for, when said starter position detecting means detects said ignition switch in said starter position, releasing the connection of said clutch, controlling said second motor-driving circuit to enable said second motor to output a torque to said drive shaft with the power stored in said storage battery, and controlling said first motor-driving circuit to enable said first motor to transmit the torque, which is output from said second motor to said drive shaft, to said output shaft of said engine and thereby cranking said output shaft of said engine; and

engine operation control means for injecting a fuel into said engine and igniting a spark in said engine concurrently with the cranking operation by said cranking control means.

8. A power transmitting apparatus for starting an engine and transmitting power output from said engine to a drive shaft, said power transmitting apparatus comprising:

a clutch motor comprising a first rotor connected with an output shaft of said engine and a second rotor connected with said drive shaft, said second rotor being coaxial to and rotatable relative to said first rotor, said first and second rotors being electromagnetically connected with each other to transmit power between said output shaft of said engine and said drive shaft via the electromagnetic connection of said first and second rotors;

a clutch motor-driving circuit for controlling a degree of the electromagnetic connection of said first and second rotors of said clutch motor and regulating rotation of said second rotor relative to said first rotor;

an assist motor connected with said drive shaft;

an assist motor-driving circuit for driving and controlling said assist motor;

a storage battery being charged with power regenerated by said clutch motor via said clutch motor-driving circuit, being charged with power regenerated by said assist motor via said assist motor-driving circuit, discharging power required to drive said clutch motor via said clutch motor-driving circuit, and discharging power required to drive said assist motor via said assist motor-driving circuit;

cranking control means for controlling said clutch motor-driving circuit to allow said clutch motor to crank said output shaft of said engine with the power stored in said storage battery, in response to an engine start signal which said cranking control means receives while said assist motor is driving and rotating said drive shaft with the power stored in said storage battery under a non-driving condition of said engine;

power increase means for controlling said assist motor-driving circuit to increase additional power supplied from said assist motor to said drive shaft by an amount corresponding to a torque substantially equivalent to a torque applied from said clutch motor to said output shaft of said engine, concurrently with the cranking operation by said cranking control means; and

engine operation control means for injecting a fuel into said engine and igniting a spark in said engine concurrently with the cranking operation by said cranking control means.

9. A power transmitting apparatus for starting an engine and transmitting power output from said engine to a drive shaft, said power transmitting apparatus comprising:

a complex motor comprising a first rotor connected with an output shaft of said engine, a second rotor connected with said drive shaft being coaxial to and rotatable relative to said first rotor, and a stator for rotating said second rotor, said first rotor and said second rotor constituting a first motor, said second rotor and said stator constituting a second motor;

a first motor-driving circuit for driving and controlling said first motor in said complex motor;

a second motor-driving circuit for driving and controlling said second motor in said complex motor;

a storage battery being charged with power regenerated by said first motor via said first motor-driving circuit, being charged with power regenerated by said second motor via said second motor-driving circuit, discharging power required to drive said first motor via said first motor-driving circuit, and discharging power required to drive said second motor via said second motor-driving circuit;

cranking control means for controlling said first motor-driving circuit to allow said first motor to crank said output shaft of said engine with the power stored in said storage battery, in response to an engine start signal which said cranking control means receives while said second motor is driving and rotating said drive shaft with the power stored in said storage battery under a non-driving condition of said engine;

power increase means for controlling said second motor-driving circuit to increase additional power supplied from said second motor to said drive shaft by an amount corresponding to a torque substantially equivalent to a torque applied from said first motor to said output shaft of said engine, concurrently with the cranking operation by said cranking control means; and

engine operation control means for injecting a fuel into said engine and igniting a spark in said engine concurrently with the cranking operation by said cranking control means.

10. A power transmitting apparatus for starting an engine and transmitting power output from said engine to a drive shaft, said power transmitting apparatus comprising:

a clutch motor comprising a first rotor connected with an output shaft of said engine and a second rotor connected with said drive shaft, said second rotor being coaxial to and rotatable relative to said first rotor, said first and second rotors being electromagnetically connected with each other to transmit power between said output shaft of said engine and said drive shaft via the electromagnetic connection of said first and second rotors;

a clutch motor-driving circuit for controlling a degree of the electromagnetic connection of said first and second rotors of said clutch motor and regulating rotation of said second rotor relative to said first rotor;

an assist motor connected with said output shaft of said engine;

an assist motor-driving circuit for driving and controlling said assist motor;

a storage battery being charged with power regenerated by said clutch motor via said clutch motor-driving circuit, being charged with power regenerated by said assist motor via said assist motor-driving circuit, discharging power required to drive said clutch motor via said clutch motor-driving circuit, and discharging power required to drive said assist motor via said assist motor-driving circuit;

starter position detecting means for detecting an ignition switch in a starter position;

starter control means for, when said starter position detecting means detects said ignition switch in said starter position, controlling said assist motor-driving circuit to allow said assist motor to crank said output shaft of said engine with the power stored in said storage battery; and

engine operation control means for injecting a fuel into said engine and igniting a spark in said engine concurrently with the cranking operation by said starter control means.

11. A power transmitting apparatus for starting an engine and transmitting power output from said engine to a drive shaft, said power transmitting apparatus comprising:

a complex motor comprising a first rotor connected with an output shaft of said engine, a second rotor connected with said drive shaft being coaxial to and rotatable relative to said first rotor, and a stator for rotating said second rotor, said first rotor and said second rotor constituting a first motor, said first rotor and said stator constituting a second motor;

a first motor-driving circuit for driving and controlling said first motor in said complex motor;

a second motor-driving circuit for driving and controlling said second motor in said complex motor;

a storage battery being charged with power regenerated by said first motor via said first motor-driving circuit, being charged with power regenerated by said second motor via said second motor-driving circuit, discharging power required to drive said first motor via said first motor-driving circuit, and discharging power required to drive said second motor via said second motor-driving circuit;

starter position detecting means for detecting an ignition switch in a starter position;

starter control means for, when said starter position detecting means detects said ignition switch in said starter position, controlling said second motor-driving circuit to allow said second motor to crank said output shaft of said engine with the power stored in said storage battery; and

engine operation control means for injecting a fuel into said engine and igniting a spark in said engine concurrently with the cranking operation by said starter control means.

12. A power transmitting apparatus for starting an engine and transmitting power output from said engine to a drive shaft, said power transmitting apparatus comprising:

a clutch motor comprising a first rotor connected with an output shaft of said engine and a second rotor connected with said drive shaft, said second rotor being coaxial to and rotatable relative to said first rotor, said first and second rotors being electromagnetically connected with each other to transmit power between said output shaft of said engine and said drive shaft via the electromagnetic connection of said first and second rotors;

a clutch motor-driving circuit for controlling a degree of the electromagnetic connection of said first and second rotors of said clutch motor and regulating rotation of said second rotor relative to said first rotor;

an assist motor connected with said output shaft of said engine;

an assist motor-driving circuit for driving and controlling said assist motor;

a storage battery being charged with power regenerated by said clutch motor via said clutch motor-driving circuit, being charged with power regenerated by said assist motor via said assist motor-driving circuit, discharging power required to drive said clutch motor via said clutch motor-driving circuit, and discharging power required to drive said assist motor via said assist motor-driving circuit;

lock means for setting said drive shaft into a locking state;

starter position detecting means for detecting an ignition switch in a starter position;

cranking control means for, when said starter position detecting means detects said ignition switch in said starter position, activating said lock means to set said drive shaft into the locking state and controlling said clutch motor-driving circuit to allow said clutch motor to crank said output shaft of said engine with the power stored in said storage battery; and

engine operation control means for injecting a fuel into said engine and igniting a spark in said engine concurrently with the cranking operation by said cranking control means.

13. A power transmitting apparatus for starting an engine and transmitting power output from said engine to a drive shaft, said power transmitting apparatus comprising:

a complex motor comprising a first rotor connected with an output shaft of said engine, a second rotor connected with said drive shaft being coaxial to and rotatable relative to said first rotor, and a stator for rotating said second rotor, said first rotor and said second rotor constituting a first motor while said first rotor and said stator constituting a second motor;

a first motor-driving circuit for driving and controlling said first motor in said complex motor;

a second motor-driving circuit for driving and controlling said second motor in said complex motor;

a storage battery being charged with power regenerated by said first motor via said first motor-driving circuit, being charged with power regenerated by said second motor via said second motor-driving circuit, discharging power required to drive said first motor via said first motor-driving circuit, and discharging power required to drive said second motor via said second motor-driving circuit;

lock means for setting said drive shaft into a locking state;

starter position detecting means for detecting an ignition switch in a starter position;

cranking control means for, when said starter position detecting means detects said ignition switch in said starter position, activating said lock means to set said drive shaft into the locking state and controlling said first motor-driving circuit to allow said first motor to crank said output shaft of said engine with the power stored in said storage battery; and

engine operation control means for injecting a fuel into said engine and igniting a spark in said engine concurrently with the cranking operation by said cranking control means.

14. A power transmitting apparatus for starting an engine and transmitting power output from said engine to a drive shaft, said power transmitting apparatus comprising:

a clutch motor comprising a first rotor connected with an output shaft of said engine and a second rotor connected with said drive shaft, said second rotor being coaxial to and rotatable relative to said first rotor, said first and second rotors being electromagnetically connected with each other to transmit power between said output shaft of said engine and said drive shaft via the electromagnetic connection of said first and second rotors;

a clutch motor-driving circuit for controlling a degree of the electromagnetic connection of said first and second rotors of said clutch motor and regulating rotation of said second rotor relative to said first rotor;

an assist motor connected with said output shaft of said engine;

an assist motor-driving circuit for driving and controlling said assist motor;

a storage battery being charged with power regenerated by said clutch motor via said clutch motor-driving circuit, being charged with power regenerated by said assist motor via said assist motor-driving circuit, discharging power required to drive said clutch motor via said clutch motor-driving circuit, and discharging power required to drive said assist motor via said assist motor-driving circuit;

engine stop-time driving control means for controlling said assist motor-driving circuit to allow said assist motor to lock said output shaft of said engine with the power stored in said storage battery, and controlling said clutch motor-driving circuit to allow said clutch motor to drive and rotate said drive shaft with the power stored in said storage battery, thereby driving and rotating said drive shaft under a non-driving condition of said engine;

cranking control means for controlling said assist motor-driving circuit to allow said assist motor to crank said output shaft of said engine with the power stored in said storage battery, in place of the control of said assist motor-driving circuit by said engine stop-time driving control means, in response to an engine start signal which said cranking control means receives during the course of the control by said engine stop-time driving control means; and

engine operation control means for injecting a fuel into said engine and igniting a spark in said engine concurrently with the cranking operation by said cranking control means.

15. A power transmitting apparatus for starting an engine and transmitting power output from said engine to a drive shaft, said power transmitting apparatus comprising:

a complex motor comprising a first rotor connected with an output shaft of said engine, a second rotor connected with said drive shaft being coaxial to and rotatable relative to said first rotor, and a stator for rotating said second rotor, said first rotor and said second rotor constituting a first motor while said first rotor and said stator constituting a second motor;

a first motor-driving circuit for driving and controlling said first motor in said complex motor;

a second motor-driving circuit for driving and controlling said second motor in said complex motor;

a storage battery being charged with power regenerated by said first motor via said first motor-driving circuit, being charged with power regenerated by said second motor via said second motor-driving circuit, discharging power required to drive said first motor via said first motor-driving circuit, and discharging power required to drive said second motor via said second motor-driving circuit;

engine stop-time driving control means for controlling said second motor-driving circuit to allow said second motor to lock said output shaft of said engine with the power stored in said storage battery, and controlling said first motor-driving circuit to allow said first motor to drive and rotate said drive shaft with the power stored in said storage battery, thereby driving and rotating said drive shaft under a non-driving condition of said engine;

cranking control means for controlling said second motor-driving circuit to allow said second motor to crank said output shaft of said engine with the power stored in said storage battery, in place of the control of said second motor-driving circuit by said engine stop-time driving control means, in response to an engine start signal which said cranking control means receives during the course of the control by said engine stop-time driving control means; and

engine operation control means for injecting a fuel into said engine and igniting a spark in said engine concurrently with the cranking operation by said cranking control means.

16. A method of controlling power transmitting apparatus for transmitting power output from an engine to a drive shaft, said power transmitting apparatus including:

a clutch motor comprising a first rotor connected with an output shaft of said engine and a second rotor connected with said drive shaft, said second rotor being coaxial to and rotatable relative to said first rotor, said first and second rotors being electromagnetically connected with each other to transmit power between said output shaft of said engine and said drive shaft via the electromagnetic connection of said first and second rotors;

an assist motor connected with said drive shaft;

a storage battery being charged with power regenerated by said clutch motor, being charged with power regenerated by said assist motor, discharging power required to drive said clutch motor, and discharging power required to drive said assist motor; and

an engine operation means for injecting a fuel into said engine and igniting a spark in said engine;

said method comprising the steps of;

(a) detecting an ignition switch in a starter position;

(b) setting said drive shaft into a locking state when the ignition switch is detected in the starter position;

(c) cranking said output shaft of said engine by said clutch motor with the power stored in said storage battery; and

(d) controlling the fuel injection into said engine and the spark ignition in said engine via said engine operation means concurrently with the cranking operation of said step (c).

17. A method of controlling power transmitting apparatus for transmitting power output from an engine to a drive shaft, said power transmitting apparatus including:

a clutch motor comprising a first rotor connected with said output shaft of said engine and a second rotor connected with said drive shaft, said second rotor being coaxial to and rotatable relative to said first rotor, said first and second rotors being electromagnetically connected with each other to transmit power between said output shaft of said engine and said drive shaft via the electromagnetic connection of said first and second rotors;

an assist motor connected with said drive shaft;

a storage battery being charged with power regenerated by said clutch motor, being charged with power regenerated by said assist motor, discharging power required to drive said clutch motor, and discharging power required to drive said assist motor;

an engine operation means for injecting a fuel into said engine and igniting a spark in said engine; and

a clutch mounted on said drive shaft to receive an output of said assist motor, said clutch connecting and disconnecting transmission of the output;

said method comprising the steps of;

(a) detecting an ignition switch in a starter position;

(b) releasing the connection of said clutch when the ignition switch is detected in the starter position;

(c) controlling said assist motor to output a torque to said drive shaft with the power stored in said storage battery;

(d) controlling said clutch motor to transmit the torque, which is output from said assist motor to said drive shaft, to said output shaft of said engine and thereby cranking said output shaft of said engine; and

(e) controlling the fuel injection into said engine and the spark ignition in said engine via said engine operation means concurrently with the cranking operation of said step (d).

18. A method of controlling power transmitting apparatus for transmitting power output from an engine to a drive shaft, said power transmitting apparatus including:

a clutch motor comprising a first rotor connected with said output shaft of said engine and a second rotor connected with said drive shaft, said second rotor being coaxial to and rotatable relative to said first rotor, said first and second rotors being electromagnetically connected with each other to transmit power between said output shaft of said engine and said drive shaft via the electromagnetic connection of said first and second rotors;

an assist motor connected with said drive shaft;

a storage battery being charged with power regenerated by said clutch motor, being charged with power regenerated by said assist motor, discharging power required to drive said clutch motor, and discharging power required to drive said assist motor; and

an engine operation means for injecting a fuel into said engine and igniting a spark in said engine;

said method comprising the steps of;

(a) cranking said output shaft of said engine by said clutch motor with the power stored in said storage battery, when an engine start signal is detected while said assist motor is driving and rotating said drive shaft with the power stored in said storage battery under a non-driving condition of said engine;

(b) increasing additional power supplied from said assist motor to said drive shaft by an amount corresponding to a torque substantially equivalent to a torque applied from said clutch motor to said output shaft of said engine, concurrently with the cranking operation of said step (a); and

(c) controlling the fuel injection into said engine and the spark ignition in said engine via said engine operation means concurrently with the cranking operation of said step (a).