GB2290507A - Bicycle chain transmission assembly - Google Patents
Bicycle chain transmission assembly Download PDFInfo
- Publication number
- GB2290507A GB2290507A GB9412082A GB9412082A GB2290507A GB 2290507 A GB2290507 A GB 2290507A GB 9412082 A GB9412082 A GB 9412082A GB 9412082 A GB9412082 A GB 9412082A GB 2290507 A GB2290507 A GB 2290507A
- Authority
- GB
- United Kingdom
- Prior art keywords
- sprocket
- primary
- unit
- rear wheel
- wheel axle
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
- B62M9/00—Transmissions characterised by use of an endless chain, belt, or the like
- B62M9/04—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Transmission Devices (AREA)
- Devices For Conveying Motion By Means Of Endless Flexible Members (AREA)
Abstract
The transmission assembly has a first and second drive sprocket 31, 42 mounted respective ends of a drive axle 221 driving first and second driven sprockets 35, 46 mounted on respective ends of a driven axle. Paired with each driven sprocket is an idle sprocket 34, 44 and first and second drive chains 37, 47 can be selected to engage with the first driven sprocket 35 and the second idle sprocket, 44, or the first idle sprocket 34 and the second driven sprocket 46 respectively, so increasing the number of selectable gear ratios. <IMAGE>
Description
BICYCLE POWER TRAIN ASSEMBLY
This invention relates to a bicycle power train assembly, more particularly to a bicycle power train assembly which permits a further reduction in the force which is to be applied when climbing an uphill slope.
A conventional bicycle power train assembly comprises a pedal which is used to rotate a crank axle and a driving sprocket cluster unit. A driven sprocket cluster unit is mounted on a rear wheel axle. A drive chain is trained between the driving and driven sprocket cluster units. Front and rear derailleur units are provided to train the drive chain on a selected sprocket of the sprocket cluster units.
Note that the smallest sprocket of the driving sprocket cluster unit should not be too small so as to prevent the front derailleur unit from latching onto the bicycle frame.
The bicycle power train assembly further includes a tension wheel which is operated so as to compensate for the resulting difference in the tension of the drive chain when the drive chain is trained from one sprocket to another. Note that the largest sprocket of the driven sprocket cluster unit should not be too large.
Otherwise, the required length of the drive chain becomes longer, making it difficult for the tension wheel to maintain the drive chain in tension when the drive chain is trained on the smaller sprockets of the driving and driven sprocket cluster units.
Note that less force is required to move the bicycle forward if the drive chain is trained on the smallest sprocket of the driving sprocket cluster unit.
However, since the size of the smallest sprocket of the driving sprocket cluster unit cannot be too small because of the above mentioned reason, a further reduction in the force which is to be applied when climbing an uphill slope is not possible.
Therefore, the main objective of the present invention is to provide a bicycle power train assembly which permits a further reduction in the force that is to be applied when climbing an uphill slope.
According to the present invention, a bicycle power train assembly includes a crank axle, a primary driving sprocket cluster unit, a rear wheel axle, a primary driven sprocket cluster unit, a primary drive chain, a secondary driving sprocket unit, a secondary driven sprocket, a secondary drive chain, a first sprocketmounting member, a first idle sprocket, a first rear derailleur unit, a second sprocket-mounting member, a second idle sprocket and a second rear derailleur. The crank axle has first and second ends. The primary driving sprocket cluster unit is mounted on the first end of the crank axle and has a plurality of primary driving sprockets of varying diameters. The rear wheel axle has first and second ends. The primary driven sprocket cluster unit is mounted on the first end of the rear wheel axle and has a plurality of primary driven sprockets of varying diameters.The primary drive chain is trained between the primary driving cluster unit and the primary driven sprocket cluster unit. Therefore, rotation of the primary driving sprocket cluster unit is transmitted to drive rotatably the rear wheel axle when the primary drive chain trains the primary driving sprocket cluster unit and the primary driven sprocket cluster unit. The secondary driving sprocket unit is mounted on the second end of the crank axle and rotates with the crank axle. The secondary driving sprocket unit is smaller than a smallest one of the primary driving sprockets. The secondary driven sprocket is mounted on the second end of the rear wheel axle and is larger than a largest one of the primary driven sprockets. The secondary drive chain is trained between the secondary driving sprocket unit and the secondary driven sprocket.The first sprocket-mounting member has an inner race mounted securely on the first end of the rear wheel axle adjacent the primary driven sprocket cluster unit and an outer race which is rotatable freely relative to the rear wheel axle. The first idle sprocket is mounted securely on the outer race of the first sprocketmounting member. The first rear derailleur unit is disposed adjacent to the first end of the rear wheel axle and is operable to train the primary drive chain between the primary driving sprocket cluster unit and a selected one of the primary driven sprocket cluster unit and the first idle sprocket. The second sprocketmounting member has an inner race which is mounted securely on the second end of the rear wheel axle adjacent the secondary driven sprocket and an outer race which is rotatable freely relative to the rear wheel axle.The second idle sprocket is mounted securely on the outer race of the second sprocketmounting member. The second rear derailleur unit is disposed adjacent to the second end of the rear wheel axle and is operable to train the secondary drive chain between the secondary driving sprocket unit and a selected one of the second idle sprocket and the secondary driven sprocket.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment, with reference to the accompanying drawings, of which:
Fig. 1 is an illustration of the preferred embodiment of a bicycle power train assembly according to the present invention when installed on a bicycle frame;
Fig. 2 is an exploded view of the preferred embodiment;
Fig. 3 is a schematic exploded view of a first sprocket-mounting member on which a first idle sprocket is mounted;
Fig. 4 is a sectional view showing the first sprocket-mounting member when the first idle sprocket is mounted thereon;
Fig. 5 is a top view of the preferred embodiment when in a semi-assembled state;
Fig. 6 is an enlarged view showing the preferred embodiment when installed on a bicycle frame, viewed from a direction opposite to that of Fig. 1;;
Fig. 7 is a rear view of the preferred embodiment when in a first normal operating mode;
Fig. 8 is a rear view of the preferred embodimant when in a second normal operating mode; and
Fig. 9 is a rear view of the preferred embodiment when in a force reduction operating mode.
Referring to Figs. 1 and 2, a bicycle power train assembly according to the present invention is shown to be installed on a bicycle frame (20). The bicycle frame (20) includes a seat tube (21) and a pair of chain stays (211) which are secured to a tubular connector (212). The crank axle (221) of a crank arm (22) extends into the tubular connector (212) and has first and second ends which extend out of the tubular connector (212) and which are respectively formed with ratchet teeth (23,41). A rear wheel axle (25) is mounted rotatably on one end of the chain stays (211).
A disc (250) is formed on an intermediate portion of the axle (25). The axle (25) is further formed with an annular seat (251) which is disposed on one side of the disc (250). The two ends of the axle (25) are respectively formed with rearwardly inclining ratchet teeth (26,45).
A primary driving sprocket cluster unit (31) is mounted on the first end of the crank axle (221). The primary driving sprockets (311) of the primary driving sprocket cluster unit (31) are of varying diameters and engage the ratchet teeth (23) of the crank axle (221).
A front derailleur unit (32) is secured onto the seat tube (21) adjacent to the primary driving spr-oc: < et cluster unit (31). Referring now to Figs. 3 and 4, a first sprocket-mounting member (33) includes a ballreceiving cylindrical element (33A) which serves as an inner race of the sprocket-mounting member and which comprises an outwardly threaded tube (331) mounted securely on a first end of the rear wheel axle (26).
The threaded tube (331) has a first end portion to which an annular member (332) is screwed and a second end portion from which an annular flange (330) projects radially and outwardly. The adjacent sides of the annular member (332) and the flange (330) cooperatively confine a peripheral ball-receiving groove therebetween. A plurality of rolling balls (336) are received in the ball-receiving groove. A ring (337) is sleeved on the annular member (332) and the flange (330) and has an inner wall surface that is in contact with the rolling balls (336) to permit free rotation of the ring (337) relative to the rear wheel axle (25).
The ring (337) serves as an outer race of the first sprocket-mounting member (33). A first idle sprocket (34) is mounted securely on the ring (337). A primary driven sprocket cluster unit (35) is provided on the first end of the rear wheel axle (25) on one side of the first idle sprocket (34). The primary driven sprockets (351) of the primary driven sprocket cluster unit (35) are of varying diameters and are provided with forwardly inclining ratchet teeth (301) which engage the ratchet teeth (26) of the axle (25). A first rear derailleur unit (36) is secured on one of the chain stays (211) adjacent to the primary driven sprocket cluster unit (35). A primary drive chain (37) is trained between the primary driving and driven sprocket cluster units (31,35).The front derailleur unit (32) and the first rear derailleur unit (36) are operated so as to train the primary drive chain (36) on a selected sprocket (311,351) of the sprocket cluster units (31,35).
Referring to Figs. 1, 2, 5 and 6, a secondary driving sprocket unit (42) is mounted on the second end of the crank axle (221) on the side of the bicycle frame (20) opposite to the sprocket cluster units (31,35). The secondary driving sprocket unit (42) has a plurality of secondary driving sprockets (421) of varying diameters. The largest sprocket (421) is smaller than the smallest sprocket (311) of the primary driving sprocket cluster unit (31). The sprockets (421) engage the ratchet teeth (41) of the crank axle (221). A secondary driven sprocket (46) is mounted on the second end of the rear wheel axle (25) on the other side of the disc (250) opposite to the idle sprocket (34).The secondary driven sprocket (46) is larger than the largest sprocket (351) of the primary driven sprocket cluster unit (35) and is provided with forwardly inclining ratchet teeth (461) which cooperate with the ratchet teeth (45) of the axle (25) to form a ratchet clutch unit. A secondary driven chain (47) is trained between the secondary driving sprocket unit (42) and the secondary driven sprocket (46). A second sprocket-mounting member (43) is provided on the second end of the axle (25) between the disc (250) and the secondary driven sprocket (46). Since the construction of the second sprocket-mounting member (43) is similar to that of the first sprocket-mounting member (33), a detailed description of the second sprocket-mounting member (43) will be omitted herein.A second idle sprocket (44) is mounted securely on an outer race of the second sprocket-mounting member (43) so as to rotate freely relative to the axle (25). A second rear derailleur unit (48) is secured on the other one of the chain stays (211) adjacent to the secondary driven sprocket (46) and is operable to train the secondary drive chain (47) between the secondary driving sprocket unit (42) and a selected one of the second idle sprocket (44) and the secondary driven sprocket (46).
A front derailleur unit (49) is secured onto the seat tube (21) adjacent to the secondary driving sprocket unit (42) and is operable to train the secondary drive chain (47) on a selected one of the secondary driving sprockets (421).
The operation of the preferred embodiment is as follows:
Referring to Figs. 1, 5 and 7, when the preferred embodiment is in the first normal operating mode, a pedal (220) secured on one end of the crank arm (22) is operated so as to rotate the crank arm (22) and thereby rotate the crank axle (221). The crank axle (221) causes the primary driving sprocket cluster unit (31) to rotate therewith and move the primary drive chain (37). The primary drive chain (37) is trained on a selected one of the sprockets (351) of the primary driven sprocket cluster unit (35), thereby causing the latter to rotate. Rotation of the primary driven sprocket cluster (35) is transmitted to the axle (25), thereby enabling the bicycle to move forward.
Note that operation of the crank arm (22) does not only result in the rotation of the primary driving sprocket cluster unit (31), the primary drive chain (37) and the primary driven sprocket cluster unit (35), but also results in the rotation of the secondary driving sprocket unit (42), the secondary drive chain (47) and the secondary driven sprocket (46). Since the ratio of the diameters of the secondary driving sprocket unit (42) and the secondary driven sprocket (46) is smaller than that of the trained sprockets (311,351) of the primary driving and driven sprocket cluster units (31,35), the secondary driven sprocket (46) rotates at a slower pace as compared to the axle (25). The ratchet teeth (45) of the axle (25) move past the ratchet teeth (461) of the secondary driven sprocket (46) and do not engage the same.The secondary driven sprocket (46) therefore rotates idly relative to the axle (25) and does not exert any force on the same. The front derailleur unit (32) and the first rear derailleur unit (36) may be operated so as to train the primary drive chain (37) on a selected sprocket (311,351) of the sprocket cluster units (31,35) to vary the speed setting of the bicycle.
Referring to Fig. 8, the preferred embodiment is in the second normal operating mode when the second rear derailleur unit (48) is operated so as to train the secondary drive chain (47) on the second idle sprocket (44). The advantage of the second normal operating mode is that the time for training the secondary drive chain (47) on the secondary driven sprocket (46) is reduced, thereby allaying the wearing of the secondary driven sprocket (46) and extending the life-time of the same.
When climbing an uphill slope, the front derailleur unit (32) is operated so as to train the primary drive chain (37) on the smallest sprocket (311) of the primary driving sprocket cluster unit (31), and the first rear derailleur unit (36) is operated so as to train the primary drive chain (37) on the largest sprocket (351) of the primary driven sprocket cluster unit (35). Less force is therefore required so as to move the bicycle along the uphill slope. Note that the size of the smallest sprocket (311) of the primary driving sprocket cluster unit (31) should not be too small in order to prevent the front derailleur unit (32) from latching onto one of the chain stays (211).
A further reduction in the force which is to be applied so as to move the bicycle along the uphill slope is therefore not possible with the use of the primary driving sprocket cluster unit (31).
Referring to Figs. 1, 5, 8 and 9, in order to permit further reductions in the required applied force, supposing the preferred embodiment is in the second normal operating mode, the second derailleur unit (48) is initially operated so as to train the secondary drive chain (47) onto the secondary driven sprocket (46), and the first rear derailleur unit (36) is operated so as to train the primary drive chain (37) onto the first idle sprocket (34). Rotation of the primary driving sprocket cluster unit (31) can therefore cause the rotation of the first idle sprocket (34) but does not cause the rotation of the axle (25) since the first idle sprocket (34) is incapable of rotatably driving the axle (25).Initially, the axle (25) is stationary relative to the secondary driven sprocket (46), thereby causing the ratchet teeth (461) of the secondary driven sprocket (46) to engage the ratchet teeth (45) of the axle (25) and cause the axle (25) to rotate and enable the bicycle to move forward.
A reduction in the force which is to be applied when climbing an uphill slope is thus obtained since the ratio of the diameters of the secondary driving sprocket unit (42) and the secondary driven sprocket (46) is smaller than that of the sprockets (311,351) of the primary driving and driven sprocket cluster units (31,35).
It should be appreciated that the front derailleur unit (49) is operable to train the secondary drive chain (47) onto a selected one of the secondary driving sprockets (421) of the secondary driving sprocket cluster unit (42). Different ratios in the diameters of the secondary driving and driven sprockets (421,46) are thus obtained so as to provide additional speed settings for the bicycle.
Claims (4)
1. A bicycle power train assembly, comprising:
a crank axle having first and second ends;
a primary driving sprocket cluster unit mounted on said first end of said crank axle and having a plurality of primary driving sprockets of varying diameters;
a rear wheel axle having first and second ends;
a primary driven sprocket cluster unit mounted on said first end of said rear wheel axle and having a plurality of primary driven sprockets of varying diameters;
a primary drive chain trained between said primary driving cluster unit and said primary driven sprocket cluster unit, rotation of said primary driving sprocket cluster unit being transmitted to drive rotatably said rear wheel axle when said primary drive chain trains said primary driving sprocket cluster unit and said primary driven sprocket cluster unit;;
a secondary driving sprocket unit mounted on said second end of said crank axle and rotating with said crank axle, said secondary driving sprocket unit being smaller than a smallest one of said primary driving sprockets;
a secondary driven sprocket mounted on said second end of said rear wheel axle and larger than a largest one of said primary driven sprockets;
a secondary drive chain trained between said secondary driving sprocket unit and said secondary driven sprocket;
a first sprocket-mounting member having an inner race mounted securely on said first end of said rear wheel axle adjacent said primary driven sprocket cluster unit and an outer race which is rotatable freely relative to said rear wheel axle;
a first idle sprocket mounted securely on said outer race of said first sprocket-mounting member;;
a first rear derailleur unit disposed adjacent to said first end of said rear wheel axle and operable to train said primary drive chain between said primary driving sprocket cluster unit and a selected one of said primary driven sprocket cluster unit and said first idle sprocket;
a second sprocket-mounting member having an inner race mounted securely on said second end of said rear wheel axle adjacent said secondary driven sprocket and an outer race which is rotatable freely relative to said rear wheel axle;
a second idle sprocket mounted securely on said outer race of said second sprocket-mounting member; and
a second rear derailleur unit disposed adjacent to said second end of said rear wheel axle and operable to train said secondary drive chain between said secondary driving sprocket unit and a selected one of said second idle sprocket and said secondary driven sprocket.
2. A bicycle power train assembly as claimed in Claim 1, wherein said secondary driving sprocket unit includes a plurality of secondary driving sprockets of varying diameters, a front derailleur unit being disposed adjacent said second end of said crank axle and being operable to train said secondary drive chain on a selected one of said secondary driving sprockets.
3. A bicycle power train assembly as claimed in Claim 1, wherein said first sprocket-mounting member includes a ball-receiving cylindrical element which serves as said inner race of said sprocket-mounting member and which is mounted securely on said first end of eaid rear wheel axle, said cylindrical element having an annular outer wall surface formed with a peripheral ball-receiving groove, a plurality of rolling balls received in said ball-receiving groove, and a ring which is sleeved on said cylindrical element and which has an inner wall surface that is in contact with said rolling balls, said ring serving as said outer race of said first sprocket-mounting member and being mounted securely on said first idle sprocket.
4. A bicycle power train assembly substantially as hereinbefore described with reference to and as illustrated in Figs. 1 to 9 of the accompanying drawings.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9412082A GB2290507B (en) | 1994-06-16 | 1994-06-16 | Bicycle power train assembly |
| FR9408179A FR2721896B3 (en) | 1994-06-16 | 1994-07-01 | TRANSMISSION ASSEMBLY FOR BICYCLE |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9412082A GB2290507B (en) | 1994-06-16 | 1994-06-16 | Bicycle power train assembly |
| FR9408179A FR2721896B3 (en) | 1994-06-16 | 1994-07-01 | TRANSMISSION ASSEMBLY FOR BICYCLE |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9412082D0 GB9412082D0 (en) | 1994-08-03 |
| GB2290507A true GB2290507A (en) | 1996-01-03 |
| GB2290507B GB2290507B (en) | 1997-09-03 |
Family
ID=26231263
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9412082A Expired - Fee Related GB2290507B (en) | 1994-06-16 | 1994-06-16 | Bicycle power train assembly |
Country Status (2)
| Country | Link |
|---|---|
| FR (1) | FR2721896B3 (en) |
| GB (1) | GB2290507B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7017698B2 (en) * | 2003-11-10 | 2006-03-28 | Motoczysz Llc | Motorcycle with dual drive chains |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB650494A (en) * | 1949-03-24 | 1951-02-28 | Robert William John Shepherd | Improved transmission for bicycles |
-
1994
- 1994-06-16 GB GB9412082A patent/GB2290507B/en not_active Expired - Fee Related
- 1994-07-01 FR FR9408179A patent/FR2721896B3/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB650494A (en) * | 1949-03-24 | 1951-02-28 | Robert William John Shepherd | Improved transmission for bicycles |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7017698B2 (en) * | 2003-11-10 | 2006-03-28 | Motoczysz Llc | Motorcycle with dual drive chains |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2721896A3 (en) | 1996-01-05 |
| FR2721896B3 (en) | 1996-06-07 |
| GB2290507B (en) | 1997-09-03 |
| GB9412082D0 (en) | 1994-08-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 730A | Proceeding under section 30 patents act 1977 | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19980616 |