Permanent magnet type stepping motor

A permanent magnet type stepping motor comprising:

• a rotor having a permanent magnet element fixed on a revolving shaft;
• said permanent magnet element being constructed into a cylindrical configuration so as to permit n N magnetic poles and n S magnetic poles to alternately appear at equal pitches thereon in a circumferential direction thereof, wherein n is a positive integer of 4 or more;
• and
• a stator including two or more claw pole type yoke units juxtaposed to each other in an axial direction of said revolving shaft;
• said claw pole type yoke units each including first and second yokes and an exciting winding;
• said first and second yokes each including n pole teeth arranged opposite to said permanent magnet element at a predetermined interval in a radial direction of said revolving shaft and positioned at predetermined pitches in said circumferential direction;
• said exciting winding being constructed so as to permit said n pole teeth of said first yoke and said n pole teeth of said second yoke to be excited at polarities different from each other;
• said first and second yokes being combined with each other so that said n pole teeth of said first yoke and said n pole teeth of said second yoke are engaged with each other while being kept from being contacted with each other;
• said claw pole type yoke unit being so constructed that a pitch between each adjacent two of said pole teeth is constant;
• said n N magnetic poles and n S magnetic poles of said rotor being so arranged that pitches thereof defined supposing that a sum of widths of adjacent N magnetic poles and those of adjacent S magnetic poles is defined to be one pitch are not constant at 360°/n but include two or more different pitches between more than 270°/n and less than 450°/n;
• said two or more pitches different from each other being arranged so as to approach composite static torque to a sinusoidal wave.

A permanent magnet type stepping motor comprising:

• a rotor having a permanent magnet element fixed on a revolving shaft;
• said permanent magnet element being constructed into a cylindrical configuration so as to permit n N magnetic poles and n S magnetic poles to alternately appear at equal pitches thereon in a circumferential direction thereof, wherein n is a positive integer of 4 or more;
• and
• a stator including two or more claw pole type yoke units juxtaposed to each other in an axial direction of said revolving shaft;
• said claw pole type yoke units each including first and second yokes and an exciting winding;
• said first and second yokes each including n pole teeth arranged opposite to said permanent magnet element at a predetermined interval in a radial direction of said revolving shaft and positioned at predetermined pitches in said circumferential direction;
• said exciting winding being constructed so as to permit said n pole teeth of said first yoke and said n pole teeth of said second yoke to be excited at polarities different from each other;
• said first and second yokes being combined with each other so that said n pole teeth of said first yoke and said n pole teeth of said second yoke are engaged with each other while being kept from being contacted with each other;
• said claw pole type yoke unit being so constructed that a pitch between each adjacent two of said pole teeth is constant;
• said rotor including magnetic poles of n/m in number arranged in each of angular ranges of 360°/m, wherein m is an integer divisor of n other than 1 and n, said n/m magnetic poles being homopolar;
• each adjacent two of said n/m homopolar magnetic poles positioned in each of said angular ranges being arranged at a magnetic pole center-magnetic pole center pitch a within a range of (90°/n)[4−m/(n−m)]<a<(360°/n);
• each adjacent two of said magnetic poles positioned on each of both sides of a boundary between each adjacent two of said angular ranges being arranged at a magnetic pole center-magnetic pole center pitch b within a range of (360°/n)<b<(450°/n);
• said two or more pitches different from each other being arranged so as to approach composite static torque to a sinusoidal wave.

A permanent magnet type stepping motor comprising:

• a rotor having a permanent magnet element fixed on a revolving shaft;
• said permanent magnet element being constructed into a cylindrical configuration so as to permit n N magnetic poles and n S magnetic poles to alternately appear at equal pitches thereon in a circumferential direction thereof, wherein n is a positive integer of 4 or more;
• and
• a stator including two or more claw pole type yoke units juxtaposed to each other in an axial direction of said revolving shaft;
• said claw pole type yoke units each including first and second yokes and an exciting winding;
• said first and second yokes each including n pole teeth arranged opposite to said permanent magnet element at a predetermined interval in a radial direction of said revolving shaft and positioned at predetermined pitches in said circumferential direction;
• said exciting winding being constructed so as to permit said n pole teeth of said first yoke and said n pole teeth of said second yoke to be excited at polarities different from each other;
• said first and second yokes being combined with each other so that said n pole teeth of said first yoke and said n pole teeth of said second yoke are engaged with each other while being kept from being contacted with each other;
• said claw pole type yoke unit being so constructed that a pitch between each adjacent two of said pole teeth is constant;
• said rotor including magnetic poles of n/m in number arranged in each of angular ranges of 360°/m, wherein m is an integer divisor of n other than 1 and n, said n/m magnetic poles being homopolar;
• each adjacent two of said n/m homopolar magnetic poles positioned in each of said angular ranges being arranged at a magnetic pole center-magnetic pole center pitch a defined within a range of (45°/n)[4+m/(n−m)]>a>(180°/n);
• each adjacent two of said homopolar magnetic poles positioned on each of both sides of a boundary between each adjacent two of said angular ranges being arranged at a magnetic pole center-magnetic pole center pitch b defined within a range of (180°/n)>b>(90°/n);
• said two or more pitches different from each other being arranged so as to approach composite static torque to a sinusoidal wave.

A permanent magnet type stepping motor comprising:

• a rotor having a permanent magnet element fixed on a revolving shaft;
• said permanent magnet element being constructed into a cylindrical configuration so as to permit n N magnetic poles and n S magnetic poles to alternately appear at equal pitches thereon in a circumferential direction of said revolving shaft, wherein n is a positive integer of 4 or more;
• and
• a stator including two or more claw pole type yoke units juxtaposed to each other in an axial direction of said revolving shaft;
• said claw pole type yoke units each including first and second yokes and an exciting winding;
• said first and second yokes each including n pole teeth arranged opposite to said permanent magnet element at a predetermined interval in a radial direction of said revolving shaft and positioned at predetermined pitches in said circumferential direction;
• said exciting winding being constructed so as to permit said n pole teeth of said first yoke and said n pole teeth of said second yoke to be excited at polarities different from each other;
• said first and second yokes being combined with each other so that said n pole teeth of said first yoke and said n pole teeth of said second yoke are engaged with each other while being kept from being contacted with each other;
• said claw pole type yoke unit being so constructed that a pitch between each adjacent two of said pole teeth is constant;
• respective adjacent two of said magnetic poles of said rotor being arranged at not a constant magnetic pole center-magnetic pole center pitch of 180°/n but two or more different magnetic center magnetic center pitches a between more than 135°/n and less than 225°/n;
• said two or more pitches different from each other being arranged so as to approach composite static torque to a sinusoidal wave.