Drive system and automobile

Abstract

A counterweight 40 attached to a crankshaft 38 has a projection 42 , which is aligned with and faces an electromagnet 44 attached to a crank casing 46 when the crankshaft 38 is at a preset rotational position of ensuring good startability of an engine 22 . Engine stop control starts a power supply to the electromagnet 44 to attract the projection 42 of the counterweight 40 at a timing when the projection 42 of the counterweight 40 is practically aligned with the electromagnet 44 , on the condition that the revolution speed of the crankshaft 38 is lowered to or below a preset level immediately before a full stop of rotation of the crankshaft 38 . This engine stop control stops the rotation of the crankshaft 38 and desirably holds the crankshaft 38 at the preset rotational position of ensuring good startability of the engine 22.

1 . A drive system of driving a drive shaft, said drive system comprising: 
 an internal combustion engine having a crankshaft as its output shaft;    a position holding module that is directly attached to the crankshaft of said internal combustion engine and applies either of an electromagnetic force and a mechanical force to hold the crankshaft at a preset rotational position; and    a stop control module that, in response to fulfillment of a predetermined stop condition, controls said internal combustion engine and said position holding module to stop said internal combustion engine while holding the crankshaft at the preset rotational position, wherein said stop control module turns the crankshaft to the preset rotational position after a stop of rotation of the crankshaft.    
     
     
         2 . A drive system in accordance with  claim 1 , wherein said position holding module comprises a motion conversion mechanism that converts a rotational motion of the crankshaft into a reciprocating motion of a reciprocating member with one end set at the preset rotational position of the crankshaft, and a shift mechanism that shifts and holds the reciprocating member to the one end of the reciprocating motion.  
     
     
         3 . A drive system in accordance with  claim 2 , wherein the shift mechanism comprises an electromagnetic attraction unit that applies an electromagnetic attraction force to part of a counterweight attached to the crankshaft as an attraction target, so as to hold the crankshaft at the preset rotational position.  
     
     
         4 . A drive system in accordance with  claim 1 , said drive system further comprising: 
 an electric braking module that is capable of braking the crankshaft or the output shaft of said internal combustion engine through input and output of electric power; and    an accumulator module that is capable of transmitting electric power to and from said electric braking module,    wherein said position holding module functions as a mechanical braking module to mechanically brake the output shaft of said internal combustion engine, and    said stop control module controls said internal combustion engine to stop operation of said internal combustion engine, while controlling said electric braking module and said mechanical braking module to stop rotation of said internal combustion engine.    
     
     
         5 . A drive system in accordance with  claim 4 , wherein said stop control module controls said electric braking module and said mechanical braking module to stop the rotation of said internal combustion engine within an allowable range of a charge-discharge limit of said accumulator module.  
     
     
         6 . A drive system in accordance with  claim 4 , wherein said electric braking module comprises a motor that is capable of generating electric power, 
 said drive system further comprising:    a three shaft-type power input output module that is linked to three shafts, that is, the output shaft of said internal combustion engine, a rotation shaft of said motor, and the drive shaft, where power input to and output from a residual one shaft is automatically determined according to powers input to and output from any two shafts among the three shafts; and    a drive shaft motor that is capable of inputting and outputting power from and to the drive shaft.    
     
     
         7 . A drive system in accordance with  claim 6 , said drive system further comprising: 
 a power demand setting module that sets a power demand required to output the drive shaft,    wherein said stop control module controls said electric braking module, said drive shaft motor, and said mechanical braking module to output a power corresponding to the setting of the power demand to the drive shaft, while stopping the rotation of said internal combustion engine within an allowable range of a charge-discharge limit of said accumulator module.    
     
     
         8 . A drive system in accordance with  claim 7 , wherein said stop control module sets a target driving force of said electric braking module and a target driving force of said drive shaft motor and executes a first control of controlling said electric braking module and said drive shaft motor to produce the respective target driving forces and thereby output the power corresponding to the setting of the power demand to the drive shaft while stopping the rotation of said internal combustion engine, 
 when the first control causes a sum of an electric power input to and output from said electric braking module and an electric power input to and output from said drive shaft motor to exceed the allowable range of the charge-discharge limit of said accumulator module, said stop control module setting the target driving force of said electric braking module, the target driving force of said drive shaft motor, and a target driving force of said mechanical braking module and executing a second control of controlling said electric braking module, said drive shaft motor, and said mechanical braking module, instead of the first control, to produce the respective target driving forces while keeping the sum of the electric powers within the allowable range of the charge-discharge limit of said accumulator module.    
     
     
         9 . A drive system in accordance with  claim 4 , said drive system further comprising: 
 a drive shaft motor that is capable of inputting and outputting power from and to the drive shaft,    wherein said electric braking module comprises a pair rotor motor, which has a first rotor connected to the output shaft of said internal combustion engine and a second rotor connected to the drive shaft and relatively rotates the first rotor and the second rotor through electromagnetic interaction.    
     
     
         10 . A drive system in accordance with  claim 4 , said drive system further comprising: 
 a revolution speed measurement module that measures a revolution speed of said internal combustion engine,    wherein said stop control module controls said electric braking module and said mechanical braking module to stop the rotation of said internal combustion engine, based on the measured revolution speed.    
     
     
         11 . A drive system in accordance with  claim 10 , wherein said stop control module controls said electric braking module and said mechanical braking module to brake said internal combustion engine with at least a braking force of said mechanical braking module when the measured revolution speed of said internal combustion engine is not less than a predetermined level, while controlling said electric braking module and said mechanical braking module to brake said internal combustion engine with a braking force of said electric braking module when the measured revolution speed of said internal combustion engine is less than the predetermined level.  
     
     
         12 . A drive system in accordance with  claim 4 , wherein said stop control module controls said electric braking module and said mechanical braking module to stop said internal combustion engine at a target stop position.  
     
     
         13 . A drive system in accordance with  claim 12 , said drive system further comprising: 
 a rotational position detection module that detects a rotational position of said internal combustion engine,    wherein when the detected rotational position of said internal combustion engine is close to the target stop position, said stop control module controls said mechanical braking module to apply a braking force and stop said internal combustion engine at the target stop position.    
     
     
         14 . A drive system in accordance with  claim 13 , wherein said electric braking module comprises a motor that is capable of generating electric power, 
 said drive system further comprising:    a threes haft-type power input output module that is linked to three shafts, that is, the output shaft of said internal combustion engine, a rotation shaft of said motor, and the drive shaft, where power input to and output from a residual one shaft is automatically determined according to powers input to and output from any two shafts among the three shafts; and    a drive shaft motor that is capable of inputting and outputting power from and to the drive shaft,    wherein said rotational position detection module detects the rotational position of said internal combustion engine, based on a rotational position of said motor and a rotational position of said drive shaft motor.    
     
     
         15 . A drive system of driving a drive shaft, said drive system comprising: 
 an internal combustion engine having a crankshaft as its output shaft;    a magnetic field generation module that is arranged to generate a magnetic field of a preset magnetic polarity at a predetermined position of the crankshaft of said internal combustion engine toward an outer side of the crankshaft; and    a position holding module that utilizes a magnetic force produced by an interaction with the magnetic field generated by said magnetic field generation module to hold the crankshaft of said internal combustion engine at a preset rotational position.    
     
     
         16 . A drive system in accordance with  claim 15 , wherein said magnetic field generation module comprises a permanent magnet that is attached to the crankshaft and is magnetized to have either an S magnetic polarity or an N magnetic polarity toward the outer side of the crankshaft, and 
 said position holding module comprises a permanent magnet that is arranged in a periphery of the crankshaft to locate the crankshaft at the preset rotational position when being practically aligned with the predetermined position of the crankshaft in the course of rotation of the crankshaft, and is magnetized to have a magnetic polarity opposite to the magnetic polarity of the facing permanent magnet of said magnetic field generation module.    
     
     
         17 . A drive system in accordance with  claim 15 , wherein said magnetic field generation module comprises a permanent magnet that is attached to the crankshaft and is magnetized to have either an S magnetic polarity or an N magnetic polarity toward the outer side of the crankshaft, and 
 said position holding module comprises an electromagnet that is arranged in a periphery of the crankshaft to locate the crankshaft at the preset rotational position when being practically aligned with the predetermined position of the crankshaft in the course of rotation of the crankshaft, and is magnetized to have a magnetic polarity opposite to the magnetic polarity of the facing permanent magnet of said magnetic field generation module,    said drive system further comprising:    a power supply control module that starts a power supply to said position holding module in response to fulfillment of a predetermined stop condition to hold the crankshaft at the preset rotational position.    
     
     
         18 . A drive system in accordance with  claim 15 , said drive system further comprising: 
 a stop position restriction module that utilizes the magnetic force produced by the interaction with the magnetic field generated by said magnetic field generation module to restrain the crankshaft from stopping at an angle of approximately 90 degrees deviated from the preset rotational position.    
     
     
         19 . A drive system in accordance with  claim 12 , wherein said magnetic field generation module comprises a permanent magnet that is attached to the crankshaft and is magnetized to have either an S magnetic polarity or an N magnetic polarity toward the outer side of the crankshaft, and 
 said stop position restriction module comprises either of a permanent magnet and an electromagnet that is arranged in a periphery of the crankshaft to locate the crankshaft at the angle of approximately 90 degrees deviated from the preset rotational position when being practically aligned with the predetermined position of the crankshaft in the course of rotation of the crankshaft, and is magnetized to have a magnetic polarity identical with the magnetic polarity of the facing permanent magnet of said magnetic field generation module.    
     
     
         20 . An automobile, comprising: 
 an internal combustion engine having a crankshaft as its output shaft;    a position holding module that is directly attached to the crankshaft of said internal combustion engine and applies either of an electromagnetic force and a mechanical force to hold the crankshaft at a preset rotational position;    a stop control module that, in response to fulfillment of a predetermined auto stop condition, controls said internal combustion engine and said position holding module to stop said internal combustion engine while holding the crankshaft at the preset rotational position; and    an auto start module that, in response to fulfillment of a predetermined auto start condition, releases the hold of the crankshaft at the preset rotational position by said position holding module and starts said internal combustion engine,    wherein said automobile further comprising:    an electric braking module that is capable of braking the crankshaft or the output shaft of said internal combustion engine through input and output of electric power; and    an accumulator module that is capable of transmitting electric power to and from said electric braking module,    wherein said position holding module functions as a mechanical braking module to mechanically brake the output shaft of said internal combustion engine, and    said stop control module controls said internal combustion engine to stop operation of said internal combustion engine, while controlling said electric braking module and said mechanical braking module to stop rotation of said internal combustion engine.    
     
     
         21 . An automobile, comprising: 
 an internal combustion engine having a crankshaft as its output shaft;    a magnetic field generation module that is arranged to generate a magnetic field of a preset magnetic polarity at a predetermined position of the crankshaft of said internal combustion engine toward an outer side of the crankshaft;    a position holding module that utilizes a magnetic force produced by an interaction with the magnetic field generated by said magnetic field generation module to hold the crankshaft of said internal combustion engine at a preset rotational position;    a stop control module that, in response to fulfillment of a predetermined auto stop condition, controls said position holding module to hold the crankshaft at the preset rotational position; and    an auto start module that, in response to fulfillment of a predetermined auto start condition, releases the hold of the crankshaft at the preset rotational position by said position holding module and starts said internal combustion engine.    
     
     
         22 . A control method of a drive system that drives a drive shaft, said drive system comprising: an internal combustion engine having a crankshaft as its output shaft; and a position holding module that is directly attached to the crankshaft of said internal combustion engine and applies either of an electromagnetic force and a mechanical force to hold the crankshaft at a preset rotational position, 
 in response to fulfillment of a predetermined stop condition, said control method controlling said internal combustion engine and said position holding module to stop said internal combustion engine while holding the crankshaft at the preset rotational position,    wherein said drive system further comprises: an electric braking module that is capable of braking the crankshaft or the output shaft of said internal combustion engine through input and output of electric power; and an accumulator module that is capable of transmitting electric power to and from said electric braking module, and    said position holding module functions as a mechanical braking module to mechanically brake the output shaft of said internal combustion engine,    in response to fulfillment of the predetermined stop condition, said control method controlling said internal combustion engine to stop operation of said internal combustion engine, while controlling said electric braking module and said mechanical braking module to stop rotation of said internal combustion engine within an allowable range of a charge-discharge limit of said accumulator module.    
     
     
         23 . A control method of a drive system that drives a drive shaft, said drive system comprising: an internal combustion engine having a crankshaft as its output shaft; a magnetic field generation module that is arranged to generate a magnetic field of a preset magnetic polarity at a predetermined position of the crankshaft of said internal combustion engine toward an outer side of the crankshaft; and a position holding module that utilizes a magnetic force produced by an interaction with the magnetic field generated by said magnetic field generation module to hold the crankshaft of said internal combustion engine at a preset rotational position, 
 in response to fulfillment of a predetermined stop condition, said control method controlling said position holding module to hold the crankshaft at the preset rotational position.