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A motor-assisted bicycle and a power unit therefor in which the power unit is after-mounted on an existing bicycle frame without largely changing the design of the bicycle frame so that an assist power generated from the power unit is input into a chain drive. A power unit is formed with at least th

A motor-assisted bicycle and a power unit therefor in which the power unit is after-mounted on an existing bicycle frame without largely changing the design of the bicycle frame so that an assist power generated from the power unit is input into a chain drive. A power unit is formed with at least three boss forming spaces for forming bosses to be fixed to a bicycle frame. The power unit is fixed to the bicycle frame by selectively using any two of the bosses. The bicycle frame has a support pipe and a down pipe to which flanges are fixed, respectively. The two bosses of the power unit are bolted to the flanges, respectively, thereby fixing the power unit to the bicycle frame. In addition, a motor-assisted bicycle is provided having a chain cover for functionally covering a drive sprocket of a power unit together with a pedal sprocket and a chain without marring the appearance. An integral chain cover is composed of a drive sprocket cover portion for mainly covering a drive sprocket, a chain cover portion for mainly covering a stretched portion of a chain, and a pedal sprocket cover portion for mainly covering an upper half of a pedal sprocket. The drive sprocket cover portion for covering the drive sprocket is formed as a circular portion subjected to coloring and surface roughening so as to correspond to the outside shape of the drive sprocket, and this circular portion is positively utilized as a kind of ornament.

대표청구항 ▼

A motor-assisted bicycle and a power unit therefor in which the power unit is after-mounted on an existing bicycle frame without largely changing the design of the bicycle frame so that an assist power generated from the power unit is input into a chain drive. A power unit is formed with at least th

A motor-assisted bicycle and a power unit therefor in which the power unit is after-mounted on an existing bicycle frame without largely changing the design of the bicycle frame so that an assist power generated from the power unit is input into a chain drive. A power unit is formed with at least three boss forming spaces for forming bosses to be fixed to a bicycle frame. The power unit is fixed to the bicycle frame by selectively using any two of the bosses. The bicycle frame has a support pipe and a down pipe to which flanges are fixed, respectively. The two bosses of the power unit are bolted to the flanges, respectively, thereby fixing the power unit to the bicycle frame. In addition, a motor-assisted bicycle is provided having a chain cover for functionally covering a drive sprocket of a power unit together with a pedal sprocket and a chain without marring the appearance. An integral chain cover is composed of a drive sprocket cover portion for mainly covering a drive sprocket, a chain cover portion for mainly covering a stretched portion of a chain, and a pedal sprocket cover portion for mainly covering an upper half of a pedal sprocket. The drive sprocket cover portion for covering the drive sprocket is formed as a circular portion subjected to coloring and surface roughening so as to correspond to the outside shape of the drive sprocket, and this circular portion is positively utilized as a kind of ornament. ormable gasket attached to said face to seal the region between said burst disk and said capture flange. 5. The burst disk assembly of claim 4 wherein said securing means are circumferentially substantially equally spaced about said burst disk and said capture flange. 6. The burst disk assembly of claim 5 wherein said securing means further includes a plurality of bolt and nut assemblies with spring washers to maintain pressure on said burst disk and said capture flange. 7. The burst disk assembly of claim 6 wherein said securing means further includes a plurality of bolts to secure said capture flange within said vent. 8. The burst disk assembly of claim 7 wherein said spring washers are conical washers. 9. A burst disk assembly for use within a cryostat pressure relieving vent of a superconducting magnet system, said vent having a first end connected to a cryostat plenum and having a second end connected to an exhaust vent adapter for venting cryogenic gas away from the cryostat to the atmosphere outside the magnet in the event of an undesired pressure buildup, comprising: a) a burst disk interposed in and blocking said vent during normal operation of said superconducting magnet, said burst disk selected to burst in the event of a cryogenic gas pressure in said cryostat which exceeds a predetermined pressure in order to open a path between said cryostat and said atmosphere; b) a burst disk capture flange interposed in said vent adjacent said burst disk, said burst disk capture flange forming an annular ring having a central aperture defined within it and having a disk-bearing shoulder wherein said disk bearing shoulder includes an arcuate flat supporting the burst disk formed about a portion of its periphery; and c) securing means for said burst disk assembly extending substantially parallel to the axis of said vent to apply constant pressure to said assembly to press said burst disk and said burst disk capture flange toward each other. 10. The burst disk assembly of claim 9 wherein the flat of said capture flange is situated at the gravitational bottom of said assembly. 11. The burst disk assembly of claim 10 also including an O-ring to seal the region between the burst disk and the plenum. 12. The burst disk assembly of claim 11 also including an O-ring to seal the region between the burst disk flange and the vent adapter. 13. The burst disk assembly of claim 12 wherein said burst disk is comprised of a unitary design having a carbon graphite center portion which is surrounded by an annular stainless steel outer portion. 14. The burst disk assembly of claim 13 wherein said burst disk has a face and includes a contiguous deformable gasket attached to said face to seal the region between said burst disk and said capture flange. 15. The burst disk assembly of claim 14 wherein said securing means are circumferentially substantially equally spaced about said burst disk and said capture flange. 16. The burst disk assembly of claim 15 wherein said securing means further includes a plurality of bolt and nut assemblies with spring washers to maintain pressure on said burst disk and said capture flange. 17. The burst disk assembly of claim 16 wherein said securing means further includes a plurality of bolts to secure said capture flange within said vent. 18. The burst disk assembly of claim 17 wherein said spring washers are conical washers.