At present on the domestic and international market in the generally popular variable speed bicycle, determine that the smooth and easy whether accurate major part of its speed change is speed-changing chain group and chain.Most owners only improve the chain member in order to promote the smoothness of bicycle shift, as enlarge the width between the two chain sheets, cut down the thickness of chain sheet etc.These improvement can obtain certain effect, but the variable speed bicycle that only improves the chain member still has following shortcoming when riding: sometimes, when chain leads another gear piece from a gear piece, the cylinder of chain is often facing on the protruding position of profile of tooth, this makes whole gear shifting operation sluggishness, chain, the empty phenomenon of pedal occur striding, ride in the process or during in high-speed row, even danger can occur falling down capable riding slidingly; In addition, the speed change noise is bigger.Cause the reason of this situation be not in the speed change with chain engages, the multi-speed sprocket group that plays a crucial role makes improvements: (see figure 1) speed-changing chain group of the prior art is made of the big gear piece (1) of three concentrics, middle gear piece (2) and little gear piece (3), and its number of teeth is respectively 48 teeth, 38 teeth and 28 teeth; Datum tooth (4) is a zero degree with the angle of the datum line (6) of the line formation in the gear piece center of circle (5), 48 sprockets of rectangular distribution on big gear piece circumference, and the angle of then every adjacent bidentate is 360 ° of ÷ 48=7.5 °; By that analogy, be respectively 9.47 ° and 12.86 ° between the interdental splint of middle gear piece and little gear piece; (on the 1 speed-changing chain group of seeing Appendix on the angle change list of latch and the annex 2 speed-changing chain groups differential seat angle table of corresponding latch); Chain pitch (7) is 12.7mm, during speed change, chain (8) is by a certain meshing of another gear piece of leading from a gear piece, one oblique line distance is arranged between two teeth, if the oblique line distance is the integral multiple of chain pitch just, chain roller sleeve (21) just in time is bumped in the profile of tooth groove when then meshing, and from annex 1 as can be seen, only 360 ° of circumference, 180 ° of corresponding latch differential seat angles in position are zero, if chain (8) is directed to another gear piece time institute occurrence positions not at 360 °, chain barrel in the time of 180 ° (21) just is in the protruding position of profile of tooth when speed change.Chain (8) is in 360 ° during speed change on same circumference, 180 ° of positions, and speed change usually causes above-mentioned bad symptom as a result.
The purpose of this utility model is to provide a kind of new speed-changing chain group, and the number of teeth of its big gear piece, middle gear piece, little gear piece is respectively 40 teeth, 30 teeth and 20 teeth; On its gear piece circumference in 36 ° of angles, 72 °, 108 °, 144 °, 180 °, 216 °, 252 °, 288 °, 324 ° and 360 ° on the position of totally 10 angles, differential seat angle is zero (seeing Appendix 3); Like this, when each gear piece had 10 on same set fluted disc, because of its gear piece differential seat angle is zero, chain was imported in the gear piece mark of mouth groove of appointment in moment, had overcome the shortcoming of gear shifting operation sluggishness after the prior art gear shift; This multiple strand chain wheels oblique line distance equals the integral multiple of chain pitch, has increased smoothness, has eliminated to stride chain and pedal the sky phenomenon, the noise that has produced when also having reduced speed change.
Fig. 2 is the utility model multi-speed sprocket group scheme drawing.
Narrate the utility model technology contents and embodiment below in conjunction with accompanying drawing:
The utility model multi-speed sprocket group comprises the big gear piece (9) of the coaxial concyclic heart, middle gear piece (10) and little gear piece (11), its number of teeth is respectively 40 teeth, 30 teeth and 20 teeth, its ratio of number of teeth is 40: 30: 20, be different from the number of teeth of prior art and ratio of number of teeth 48: 38: 28, during the multi-change speed bicycle shift, when chain (13) is directed to adjacent another gear piece from arbitrary gear piece, its smooth and easy order of accuarcy depends primarily on: 1. " differential seat angle " that corresponding teeth constituted on each adjacent two gear piece heals the tooth group little the more, and chain is in preferable states when speed change speed change point is just many more; 2. the differential seat angle that corresponding teeth constituted is if can be zero, and then chain is in optimum regime when speed change meshes; 3. in speed change when engagement,, if the distance of the oblique line between two teeth integral multiple of chain pitch just, then the chain roller sleeve just in time is bumped in the profile of tooth groove, meshes smooth and easy.According to this principle, the utility model multi-speed sprocket group is respectively the coaxial concyclic heart of number of teeth ratio of 40 teeth, 30 teeth and 20 teeth with big gear piece, middle gear piece and the little gear piece number of teeth and is assembled into, on the circumference in 36 °, 72 °, 108 °, 144 °, 180 °, 216 °, 252 °, 288 °, 324 °, 360 ° the position upper angle difference of totally 10 angles be zero (the angle change list of latch on the 3 speed-changing chain groups of seeing Appendix); Relatively prior art is only on each gear piece circumference 360 °, and there is speed change optimum regime point in 180 ° of two place, because two optimization points are too little, sluggishness can take place during speed change, stride symptoms such as chain, noise.In addition, large, medium and small three gear piece pitches (22) equate with chain pitch (12), be 12.7mm, by zero design team's structure, then the oblique line of two between cog distance is the integral multiple of chain normal pitch (12) just in time with the differential seat angle between tooth (15), tooth (16) and the tooth (17) of two adjacent teeth sheet.Reach the condition of smooth and easy accurate optimum regime when therefore, the utility model structure meets bicycle shift.
The listed parameter of angle change list according to latch on the annex 3 speed-changing chain groups, it with the number of teeth 40 big gear piece (9), the number of teeth is that 30 the middle gear piece (10) and the number of teeth are 20 little gear piece (11), coaxial concyclic heart is fixed on the crank (18), apart between 4.0 to 4.5mm, chain pitch (12) is all 12.7mm mutually with the gear piece pitch length between each gear piece; The differential seat angle of the tooth (20) on tooth (19) on the middle gear piece (10) and the big gear piece (9) is zero, chain (13) is engaged on the middle gear piece (10), when speed change not, because chain pitch (12) is identical with gear piece pitch (22), chain (13) can smooth and easy engaging-in exactly tooth (19); When speed change, chain (13) is directed to big gear piece (9), because the gear piece differential seat angle is zero, chain pitch (12) is identical with the gear piece pitch, the tooth (20) of the engaging-in exactly smoothly big gear piece of meeting (9); Engagement on other correspondence positions is same smooth and easy accurately by that analogy.Annex 1
The angle change list of latch on the speed-changing chain group
Annex 2
The differential seat angle table of corresponding latch on the speed-changing chain group
Hinge wheel → middle sprocket
| Hinge wheel (48 tooth) number of teeth | Differential seat angle | Middle sprocket (38 tooth) number of teeth |
| 5 10 14 19 24 29 34 38 43 48 | 0.39 0.79 0.79 0.39 0 0.39 0.79 0.79 0.39 0 | 4 8 11 15 19 23 27 30 34 38 |
Middle sprocket → minor sprocket
| Middle sprocket (38 tooth) number of teeth | Differential seat angle | Minor sprocket (28 tooth) number of teeth |
| 4 15 19 23 34 38 | 0.68 0.68 0 0.68 0.68 0 | 3 11 14 17 25 28 |
Annex 3
The angle change list of latch on the speed-changing chain group
Annex 4
The differential seat angle table of corresponding latch on the speed-changing chain group
Hinge wheel → middle sprocket
| Hinge wheel (40 tooth) number of teeth | Differential seat angle | Middle sprocket (30 tooth) number of teeth |
| 4 8 12 16 20 24 28 32 36 40 | 0 0 0 0 0 0 0 0 0 0 | 3 6 9 12 15 18 21 24 27 30 |
Annex 5
The differential seat angle table middle sprocket → minor sprocket of corresponding latch on the speed-changing chain group
| Middle sprocket (30 tooth) number of teeth | Differential seat angle | Minor sprocket (20 tooth) number of teeth |
| 3 6 9 12 15 18 21 24 27 30 | 0 0 0 0 0 0 0 0 0 0 | 2 4 6 8 10 12 14 16 18 20 |
Annex 2
Annex 4