Toothed belt, toothed belt power transmission apparatus, and business equipment employing the same

A toothed belt comprising:

• a belt main body with a pitch line on which a tensile member is embedded therein;
• a plurality of belt tooth portions provided at a fixed pitch on a land line of said belt main body;
• each of said belt tooth portions comprising:
• tooth root portions formed of circularly arcuate surfaces which are arranged symmetrically with each other in respect to a centerline in the tooth width direction;
• power transmission portions formed of circularly arcuate surfaces of convex profile which contiguously adjoin said tooth root portions at a point, and lie at flank surfaces of said tooth portion, and are arranged symmetrically with each other in respect to said tooth width direction centerline;
• a tooth tip end portion formed of a circularly arcuate surface which is so provided as to interconnect said power transmission portions and whose center point lies on said tooth width direction centerline;
• wherein a maximum pressure angle at said point where said power transmission portion of said belt tooth flank surface and said arcuate surfaces of said tooth root portion are connected together is between an angle of 15 degrees and an angle of 25 degrees.

A toothed belt power transmission apparatus comprising a combination of a toothed belt and toothed pulleys,

• (a) said toothed belt having:
• a belt main body with a pitch line on which a tensile member is embedded therein;
• a plurality of belt tooth portions provided at a fixed pitch in said belt main body;
• a land portion provided between adjacent belt tooth portions;
• (b) each of said belt tooth portions having:
• power transmission portions formed of circularly arcuate surfaces of convex profile which lie at flank surfaces of said tooth portion and are arranged symmetrically with each other in respect to a centerline in the tooth width direction;
• tooth tip portions formed of circularly arcuate surfaces which contiguously adjoin said power transmission portions and are arranged symmetrically with each other in respect to said tooth width direction centerline;
• a tooth crest surface formed of an approximately flat surface which is so provided as to interconnect said tooth tip portions;
• (c) each of said toothed pulleys having:
• a plurality of pulley tooth groove portions provided at a fixed pitch on a pulley outside diameter line;
• (d) each of said pulley tooth groove portions having:
• tooth top arc portions formed of circularly arcuate surfaces which are arranged symmetrically with each other in respect to a centerline in the tooth groove width direction;
• tooth groove flank surface portions formed of circularly arcuate surfaces of concave profile which contiguously adjoin said tooth top arc portions and are arranged symmetrically with each other in respect to said tooth groove width direction centerline;
• a tooth groove bottom portion provided so as to interconnect said tooth groove flank surface portions at a point;
• wherein:
• a maximum pressure angle at said point where said tooth top arc portion and said tooth groove flank surface portion in said pulley tooth groove portion are connected together is between an angle of 15 degrees and an angle of 25 degrees;
• said belt tooth portion has flank surfaces whose profile is substantially the same as that of flank surfaces of said pulley tooth groove portion;
• in a power transmission state in which said toothed belt is wound around said toothed pulleys and a tension force is applied to said toothed belt, the pressure angles of said belt tooth portion flank surface and said pulley tooth groove portion flank surface at their respective locations in the tooth height direction are made approximately equal to each other and a belt land portion does not come into contact with the pulley outside diameter portion.

A toothed belt power transmission apparatus comprising a combination of a toothed belt and toothed pulleys,

• (a) said toothed belt having:
• a belt main body with a pitch line on which a tensile member is embedded therein;
• a plurality of belt tooth portions provided at a fixed pitch in said belt main body;
• a land portion provided between adjacent belt tooth portions;
• (b) each of said belt tooth portions having:
• power transmission portions formed of circularly arcuate surfaces of convex profile which lie at flank surfaces of said tooth portion and are arranged symmetrically with each other in respect to a centerline in the tooth width direction;
• a tooth tip end portion formed of a circularly arcuate surface which is so provided as to interconnect said power transmission portions and whose center point lies on said tooth width direction centerline;
• (c) each of said toothed pulleys having:
• a plurality of pulley tooth groove portions provided at a fixed pitch on a pulley outside diameter line;
• (d) each of said pulley tooth groove portions having:
• tooth top arc portions formed of circularly arcuate surfaces which are arranged symmetrically with each other in respect to a centerline in the tooth groove width direction;
• tooth groove flank surface portions formed of circularly arcuate surfaces of concave profile which contiguously adjoin said tooth top arc portions at a point and are arranged symmetrically with each other in respect to said tooth groove width direction centerline;
• a tooth groove bottom portion provided so as to interconnect said tooth groove flank surface portions;
• wherein:
• a maximum pressure angle at said point where said tooth top arc portion and said tooth groove flank surface portion in said pulley tooth groove portion are connected together is between an angle of 15 degrees and an angle of 25 degrees;
• said belt tooth portion has flank surfaces whose profile is substantially the same as that of flank surfaces of said pulley tooth groove portion;
• in a power transmission state in which said toothed belt is wound around said toothed pulleys and a tension force is applied to said toothed belt, the pressure angles of said belt tooth portion flank surface and said pulley tooth groove portion flank surface at their respective locations in the tooth height direction are made approximately equal to each other and a belt land portion does not come into contact with the pulley outside diameter portion.