Method and apparatus for controlling an electromagnetic clutch for use on a vehicle

Abstract

A method and an apparatus of controlling an electromagnetic clutch incorporated in a power transmission system of a vehicle to transmit an output of an engine to the drive wheels of the vehicle is disclosed. An amount of electric current applied to the clutch is regulated to control an engaging action of said electromagnetic clutch, based on either a variation in rotating speed or torque of an output shaft of the electromagnetic clutch, or based on the frequency or number of variations per unit time in rotating speed or torque of the output shaft, as compared with the frequency or number of ignitions or combustions per unit time of the engine. In this way a variation in output torque of the engine is absorbed by the electromagnetic clutch for improved drivability, while a transmission power loss in the clutch is kept to a minimum for maximum fuel economy.

What is claimed is: 
     
       1. A method of controlling .[.an electromagnetic.]. .Iadd.a .Iaddend.clutch .Iadd.means .Iaddend.incorporated in a power transmission system of a vehicle to transmit an output of an engine to drive wheels of the vehicle, so as to absorb a variation in output torque of the engine, .Iadd.a clutch torque transmitted by said clutch means being varied through an electromagnetic force, .Iaddend.said method comprising the steps of: detecting a variation in rotating speed or torque of an output shaft of said .[.electromagnetic.]. clutch .Iadd.means.Iaddend.; and   controlling an engaging action of said .[.electromagnetic.]. clutch .Iadd.means .Iaddend.to adjust .[.a.]. .Iadd.said .Iaddend.clutch torque transmitted by said clutch .Iadd.means.Iaddend., based on whether the detected variation in rotating speed or torque of said output shaft of said .[.electromagnetic.]. clutch .Iadd.means .Iaddend.is synchronized with an ignition period of said engine.   
     
     
       2. An apparatus for controlling .[.an electromagnetic.]. .Iadd.a .Iaddend.clutch .Iadd.means having an electromagnetic coil .Iaddend.incorporated in a power transmission system of a vehicle to transmit an output of an engine to drive wheels of the vehicle, so as to absorb a variation in output torque of the engine, an engaging action of said .[.electromagnetic.]. clutch .Iadd.means .Iaddend.being controlled to adjust a clutch torque transmitted by said clutch .Iadd.means .Iaddend.such that said clutch torque is varied as a function of an amount of electric current .Iadd.or voltage .Iaddend.applied to the .[.electromagnetic.]. clutch .Iadd.means.Iaddend., said control apparatus comprising: detecting means for detecting a specific pattern of a variation in rotating speed of an output shaft of said .[.electromagnetic.]. clutch .Iadd.means.Iaddend., the specific pattern being synchronized with an ignition period of said engine; and   current adjusting means for controlling said amount of electric current .Iadd.or voltage .Iaddend.so that the amount of electric current .Iadd.or voltage .Iaddend.is decreased when said specific pattern of variation in rotating speed of said output shaft is detected by said detecting means, and increased when said specific pattern of variation is not detected by said detecting means.   
     
     
       3. An apparatus for controlling .[.an electromagnetic.]. .Iadd.a .Iaddend.clutch .Iadd.means having an electromagnetic coil .Iaddend.incorporated in a power transmission system of a vehicle to transmit an output of an engine to drive wheels of the vehicle, so as to absorb a variation in output torque of the engine, an engaging action of said .[.electromagnetic.]. clutch .Iadd.means .Iaddend.being controlled to adjust a clutch torque transmitted by said clutch .Iadd.means .Iaddend.such that said clutch torque is varied as a function of an amount of an electric current .Iadd.or voltage .Iaddend.applied to the .[.electromagnetic.]. clutch .Iadd.means.Iaddend., said control apparatus comprising: detecting means for detecting a specific pattern of variation in torque of an output shaft of said .[.electromagnetic.]. clutch .Iadd.means.Iaddend., the specific pattern being synchronized with an ignition period of said engine; and   current adjusting means for controlling said amount of electric current .Iadd.or voltage .Iaddend.so that the amount of electric current .Iadd.or voltage .Iaddend.is decreased when said specific pattern of variation in torque of said output shaft is detected by said detecting means, and increased when said specific pattern of variation is not detected by said detecting means.   
     
     
       4. A method of controlling .[.an electromagnetic.]. .Iadd.a .Iaddend.clutch .Iadd.means .Iaddend.incorporated in a power transmission system of a vehicle to transmit an output of an engine to drive wheels of the vehicle, so as to absorb a variation in output torque of said engine, .Iadd.a clutch torque transmitted by said clutch means being varied through an electromagnetic force, .Iaddend.said method comprising the steps of: detecting a frequency of variations in rotating speed or torque of an output shaft of said .[.electromagnetic.]. clutch .Iadd.means.Iaddend.;   detecting an ignition frequency of said engine;   comparing the detected frequency of variations in rotating speed or torque of said output shaft of said .[.electromagnetic.]. clutch .Iadd.means.Iaddend., with the detected ignition frequency of said engine; and   controlling an engaging action of said .[.electromagnetic.]. clutch .Iadd.means .Iaddend.to adjust a clutch torque transmitted by said clutch .Iadd.means.Iaddend., based on whether the detected frequency of variations in rotating speed or torque of said output shaft is coincident with the detected ignition frequency of said engine.   
     
     
       5. An apparatus for controlling .[.an electromagnetic.]. .Iadd.a .Iaddend.clutch .Iadd.means having an electromagnetic coil .Iaddend.incorporated in a power transmission system of a vehicle to tranmit an output of an engine to drive wheels of the vehicle, so as to absorb a variation in output torque of said engine, an engaging action of said clutch .Iadd.means .Iaddend.being controlled to adjust a torque transmitted by said clutch .Iadd.means .Iaddend.such that said clutch torque is varied as a function of an amount of electric current .Iadd.or voltage .Iaddend.applied to the .[.electromagnetic.]. clutch .Iadd.means.Iaddend., comprising: first detecting means for detecting an ignition frequency of said engine;   second detecting means for detecting a frequency of variations in rotating speed of an output shaft of said .[.electromagnetic.]. clutch .Iadd.means.Iaddend.; and   current adjusting means for controlling said amount of electric current .Iadd.or voltage.Iaddend., said current adjusting means reducing said amount of electric current .Iadd.or voltage .Iaddend.when said frequency of variations is coincident with said ignition frequency, and increasing said amount of electric current .Iadd.or voltage,.Iaddend.when said frequency of variations is not coincident with said ignition frequency.   
     
     
       6. An apparatus for controlling .[.an electromagnetic.]. .Iadd.a .Iaddend.clutch .Iadd.means having an electromagnetic coil .Iaddend.incorporated in a power transmission system of a vehicle to transmit an output of an engine to drive wheels of the vehicle, so as to absorb a variation in output torque of said engine, an engaging action of said clutch .Iadd.means .Iaddend.being controlled to adjust a torque transmitted by said clutch means such that said clutch torque is varied as a function of an amount of electric current .Iadd.or voltage .Iaddend.applied to the .[.electromagnetic.]. clutch .Iadd.means.Iaddend., comprising: first detecting means for detecting an ignition frequency of said engine;   second detecting means for detecting a frequency of variations in torque of an output shaft of said .[.electromagnetic.]. clutch .Iadd.means.Iaddend.; and   current adjusting means for controlling said amount of electric current .Iadd.or voltage.Iaddend., said current adjusting means reducing said amount of electric current .Iadd.or voltage .Iaddend.when said frequency of variations is coincident with said ignition frequency, and increasing said amount of electric current .Iadd.or voltage .Iaddend.when said frequency of variations is not coincident with said ignition frequency.   
     
     
       7. A method of controlling .[.an electromagnetic.]. .Iadd.a .Iaddend.clutch .Iadd.means .Iaddend.incorporated in a power transmission system of a vehicle to transmit an output of an engine to drive wheels of the vehicle, so as to absorb a variation in output torque of said engine, .Iadd.a clutch torque transmitted by said clutch means being varied through an electromagnetic force, .Iaddend.said method comprising the steps of: detecting the number of ignitions per unit time of said engine;   detecting the number of variations per unit time in torque of an output shaft of said .[.electromagnetic.]. clutch .Iadd.means.Iaddend.;   comparing the detected number of ignitions per unit time of said engine with the detected number of variations per unit time in torque of said output shaft; and   controlling an engaging action of said .[.electromagnetic.]. clutch .Iadd.means .Iaddend.to transmit a clutch torque transmitted by said clutch .Iadd.means.Iaddend., such that a difference between said detected number of ignitions of the engine and said detected number of variations in torque of said output shaft coincides with a predetermined reference value.   
     
     
       8. A method as recited in claim 7, wherein said number of variations per unit time in torque of said output shaft is counted each time a waveform representative of the torque of said output shaft exceeds a predetermined threshold level. 
     
     
       9. A method as recited in claim 7, wherein said predetermined reference value is determined so as to permit maximum absorption of said variation in output torque of said engine with substantially no power loss with said .[.electromagnetic.]. clutch .Iadd.means.Iaddend.. 
     
     
       10. A method as recited in claim 7, wherein said predetermined reference value is adjusted based on a speed of said engine. 
     
     
       11. An apparatus for controlling .[.an electromagnetic.]. .Iadd.a .Iaddend.clutch .Iadd.means having an electromagnetic coil .Iaddend.incorporated in a power transmission system of a vehicle to transmit an output of an engine to drive wheels of the vehicle, so as to absorb a variation in output torque of said engine, an engaging action of said clutch .Iadd.means .Iaddend.being controlled to adjust a clutch torque transmitted by said clutch .Iadd.means .Iaddend.such that said clutch torque is varied as a function of an amount of electric current .Iadd.or voltage .Iaddend.applied to the .[.electromagnetic.]. clutch .Iadd.means.Iaddend., comprising: .[.first detecting means for detecting the number of ignitions per unit time of said engine;   second detectinutch, comprising:.].   first detecting means for detecting the number of ignitions per unit time of said engine;   second detecting means for detecting the number of variations per unit time in torque of an output shaft of said .[.electromagnetic.]. clutch .Iadd.means.Iaddend.; and   current adjusting means for controlling said amount of electric current .Iadd.or voltage .Iaddend.such that a difference between said number of ignitions of the engine and said number of variations in torque of said output shaft coincides with a predetermined reference value. .Iadd.   
     
     
       12.  An apparatus as recited in claim 11 wherein said number of variations per unit time in torque of said output shaft is counted each time a waveform representative of the torque of said output shaft exceeds a predetermined threshold level. .Iaddend. .Iadd.13. An apparatus as recited in claim 11 wherein said predetermined reference value is determined so as to permit maximum absorption of said variation in output torque of said engine with substantially no power loss within said clutch means. .Iaddend. .Iadd.14. An apparatus as recited in claim 11 wherein said predetermined reference value is adjusted based on a speed of said engine. .Iaddend. .Iadd.15. An apparatus for controlling a clutch means incorporated in a power transmission system of a vehicle for transmitting output torque of an engine to drive wheels of the vehicle, so as to absorb a variation in output torque of said engine, a clutch torque transmitted by said clutch means being varied through an electromagnetic force, said apparatus comprising: means for detecting a variation in rotating speed or torque of an output shaft of said clutch means; and   means for controlling an engaging action of said clutch means to adjust said clutch torque transmitted by said clutch means, based on whether the detected variation in rotating speed or torque of said output shaft of said clutch means is synchronized with an ignition period of said engine. .Iaddend. .Iadd.16. A method for controlling a clutch means having an electromagnetic coil incorporated in a power transmission system of a vehicle for transmitting output torque of an engine to drive wheels of the vehicle, so as to absorb a variation in output torque of said engine, an engaging action of said clutch means being controlled to adjust a torque transmitted by said clutch means such that said clutch torque is varied as a function of an amount of electric current or voltage applied to the clutch means, said method comprising the steps of:   detecting an ignition frequency of said engine;   detecting a frequency of variations in torque of an output shaft of said clutch means; and   controlling said amount of electric current or voltage by reducing said amount of electric current or voltage when said frequency of variations is coincident with said ignition frequency, and increasing said amount of electric current or voltage when said frequency of variations is not coincident with said ignition frequency. .Iaddend.