Bicycle sprocket assembly with a chain guiding means
First Claim
1. A speed varying sprocket assembly for use in combination with a driving chain of a bicycle, said speed varying sprocket assembly including a small sprocket wheel and a large sprocket wheel which are mounted coaxially so as to permit the chain to be shifted from one to the other one of said small and large sprocket wheels, tooth number of said small sprocket wheel being smaller than that of said large sprocket wheel, said large sprocket wheel having an inner side surface adjacent to said small sprocket wheel, and an annular peripheral tooth face defining a plurality of teeth each of which is provided with a tip and a bottom so as to define a tooth valley between any adjacent pair of said teeth, each of the tooth valleys having a middle point at a bottom end thereof, the improvement comprising:
- said large sprocket wheel further having several guide units each of which includes a notch formed in said large sprocket wheel, and an elongated chain guiding piece which is secured to said inner side surface of said large sprocket wheel and which is adjacent to said notch, said notches being respectively formed in some of said teeth which are spaced apart from each other, each of said notches being formed at a corner defined between said inner side surface and said annular tooth face and being defined by a curved outer guiding surface extending from the tip of a corresponding one of said teeth to one of the tooth valleys which is adjacent to the corresponding one of said teeth, each of said outer guiding surfaces having a width so as to permit an outer link plate of the chain to slide thereon, each of said pieces having a radial inner end, a radial outer end, and an inner guiding surface that has a straight intermediate portion, a curved inner end portion and a curved outer end portion which makes a junction with a corresponding one of said outer guiding surfaces so as to guide the chain to slide from said inner guiding surface to the corresponding one of said outer guiding surfaces via the junction, said straight intermediate portions of said inner guiding surfaces of said pieces being inclined with respect to axial and radial directions of said sprocket assembly so as to facilitate said chain to be shifted between said large and small sprocket wheels, each of said outer guiding surfaces having a bottom end which is spaced apart from the middle point of a corresponding one of the tooth valleys at a predetermined distance so as to make the chain engage with the corresponding one of the teeth, in such a manner that the tip of the corresponding one of the teeth contacts a lagging edge of an inner link plate of the chain, whereby, in each of the guide units, the chain can slide on the inner and outer guiding surfaces.
1 Assignment
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Accused Products
Abstract
A bicycle sprocket assembly includes a small sprocket wheel, and a large sprocket wheel coaxial with the small sprocket wheel and provided with several guide units each of which includes a notch formed in the large sprocket wheel, and a chain guiding piece that is secured to the inner side surface of the large sprocket wheel and that is adjacent to the notch. The notches are respectively formed in some spaced-apart sprocket teeth of the large sprocket wheel. Each of the notches is formed by an outer guiding surface which extends from a tooth tip to the corresponding tooth valley and which makes a junction with the inner guiding surface of the corresponding piece, so as to slide the chain between the inner and outer guiding surfaces. The pieces are inclined with respect to axial and radial directions of the sprocket assembly. Each of the outer guiding surfaces has a bottom end which is spaced apart from the middle point of the corresponding tooth valley at a predetermined distance so as to contact a tooth tip with the lagging edge of an inner link plate of the chain when shifted the chain from the small sprocket wheel to the large sprocket wheel.
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Citations
2 Claims
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1. A speed varying sprocket assembly for use in combination with a driving chain of a bicycle, said speed varying sprocket assembly including a small sprocket wheel and a large sprocket wheel which are mounted coaxially so as to permit the chain to be shifted from one to the other one of said small and large sprocket wheels, tooth number of said small sprocket wheel being smaller than that of said large sprocket wheel, said large sprocket wheel having an inner side surface adjacent to said small sprocket wheel, and an annular peripheral tooth face defining a plurality of teeth each of which is provided with a tip and a bottom so as to define a tooth valley between any adjacent pair of said teeth, each of the tooth valleys having a middle point at a bottom end thereof, the improvement comprising:
said large sprocket wheel further having several guide units each of which includes a notch formed in said large sprocket wheel, and an elongated chain guiding piece which is secured to said inner side surface of said large sprocket wheel and which is adjacent to said notch, said notches being respectively formed in some of said teeth which are spaced apart from each other, each of said notches being formed at a corner defined between said inner side surface and said annular tooth face and being defined by a curved outer guiding surface extending from the tip of a corresponding one of said teeth to one of the tooth valleys which is adjacent to the corresponding one of said teeth, each of said outer guiding surfaces having a width so as to permit an outer link plate of the chain to slide thereon, each of said pieces having a radial inner end, a radial outer end, and an inner guiding surface that has a straight intermediate portion, a curved inner end portion and a curved outer end portion which makes a junction with a corresponding one of said outer guiding surfaces so as to guide the chain to slide from said inner guiding surface to the corresponding one of said outer guiding surfaces via the junction, said straight intermediate portions of said inner guiding surfaces of said pieces being inclined with respect to axial and radial directions of said sprocket assembly so as to facilitate said chain to be shifted between said large and small sprocket wheels, each of said outer guiding surfaces having a bottom end which is spaced apart from the middle point of a corresponding one of the tooth valleys at a predetermined distance so as to make the chain engage with the corresponding one of the teeth, in such a manner that the tip of the corresponding one of the teeth contacts a lagging edge of an inner link plate of the chain, whereby, in each of the guide units, the chain can slide on the inner and outer guiding surfaces. - View Dependent Claims (2)
Specification
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- Resources
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Current AssigneeCyclone Precision Incorporated
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Original AssigneeCyclone Precision Incorporated
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InventorsLeng, Tony
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Primary Examiner(s)BUIZ, MIKADO RYAN
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Application NumberUS08/339,829Time in Patent Office357 DaysField of Search474/140, 474/152, 474/158, 474/160, 474/164US Class Current474/140CPC Class CodesB62M 9/105 involving front sprocket ch...
