CA2230426A1 - Variable ratio drive system - Google Patents
Variable ratio drive system Download PDFInfo
- Publication number
- CA2230426A1 CA2230426A1 CA 2230426 CA2230426A CA2230426A1 CA 2230426 A1 CA2230426 A1 CA 2230426A1 CA 2230426 CA2230426 CA 2230426 CA 2230426 A CA2230426 A CA 2230426A CA 2230426 A1 CA2230426 A1 CA 2230426A1
- Authority
- CA
- Canada
- Prior art keywords
- sprocket
- diameter
- variable
- apertures
- drive system
- 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.)
- Abandoned
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
- B62M9/06—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio using a single chain, belt, or the like
- B62M9/08—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio using a single chain, belt, or the like involving eccentrically- mounted or elliptically-shaped driving or driven wheel; with expansible driving or driven wheel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
- F16H55/32—Friction members
- F16H55/52—Pulleys or friction discs of adjustable construction
- F16H55/54—Pulleys or friction discs of adjustable construction of which the bearing parts are radially adjustable
Abstract
A variable ratio drive system including a variable diameter sprocket and a sprocket diameter changing mechanism is described herein. The variable diameter sprocket includes sprocket portions so mounted in radial channels of a circular support as to be radially movable therein. The sprocket portions include a pin that may be inserted in apertures of the channels. The diameter changing mechanism includes first and second angled abutting portions configured and sized to first move the sprocket portions laterally, then move them radially before allowing them to be reinserted in a new position to cause the diameter modification.
Description
TITLE OF THE INVENTION
VARIABLE RATIO DRIVE SYSTEM
FIELD OF THE INVENTION
The present invention relates to drive systems. More particularly, the present invention relates to a drive system including a variable diameter sprocket.
BACKGROUND OF THE INVENTION
Variable diameter sprockets are well known in the art.
For example, Unites States patents numbers 4,030,373; 4,832,660;
5,041,061; 5,013,284; 5,094,653; and 5,104,357 all naming Hamlin Leonard as an inventor, each describes variable speed drive systems for bicycles provided with variable diameter pulleys. By modifying the diameter of the variable diameter pulley, the ratio of the front to rear pulleys is modified.
The systems described by Leonard do not use a conventional bicycle chain but instead use a flexible driving means under the form of a V-belt. The different mechanisms described by Leonard have the same common drawback that the diameter changing mechanisms provided to modify the diameter of the pulley are generally complex. The use of a V-belt is also a drawback since it must be tensioned to prevent it from slipping. It is also to be noted that adverse temperature conditions, such as rain, may nevertheless cause the V-belt to slip in the pulleys.
OBJECTS OF THE INVENTION
An object of the present invention is therefore to provide an improved variable ratio drive system.
It is a further object of the present invention to provide a variable ratio drive system using a conventional chain.
It is also an object of the present invention to provide a variable ratio drive system provided with an improved sprocket diameter changing mechanism.
Other objects, advantages and features of the present invention will become more apparent upon reading of the following non restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the appended drawings:
VARIABLE RATIO DRIVE SYSTEM
FIELD OF THE INVENTION
The present invention relates to drive systems. More particularly, the present invention relates to a drive system including a variable diameter sprocket.
BACKGROUND OF THE INVENTION
Variable diameter sprockets are well known in the art.
For example, Unites States patents numbers 4,030,373; 4,832,660;
5,041,061; 5,013,284; 5,094,653; and 5,104,357 all naming Hamlin Leonard as an inventor, each describes variable speed drive systems for bicycles provided with variable diameter pulleys. By modifying the diameter of the variable diameter pulley, the ratio of the front to rear pulleys is modified.
The systems described by Leonard do not use a conventional bicycle chain but instead use a flexible driving means under the form of a V-belt. The different mechanisms described by Leonard have the same common drawback that the diameter changing mechanisms provided to modify the diameter of the pulley are generally complex. The use of a V-belt is also a drawback since it must be tensioned to prevent it from slipping. It is also to be noted that adverse temperature conditions, such as rain, may nevertheless cause the V-belt to slip in the pulleys.
OBJECTS OF THE INVENTION
An object of the present invention is therefore to provide an improved variable ratio drive system.
It is a further object of the present invention to provide a variable ratio drive system using a conventional chain.
It is also an object of the present invention to provide a variable ratio drive system provided with an improved sprocket diameter changing mechanism.
Other objects, advantages and features of the present invention will become more apparent upon reading of the following non restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the appended drawings:
Figure 1 is a front elevational view of a variable ratio drive system according to an embodiment of the present invention;
Figure 2 is a rear elevational view of the variable diameter sprocket of the variable ratio drive system of Figure 1;
Figure 3 is a sectional view taken along line 3-3 of Figure 1; and Figure 4 is a schematic view illustrating the operation of the sprocket diameter changing mechanism.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning now to Figures 1-3 of the appended drawings a variable ration drive system 10 according to an embodiment of the present invention will be described.
It is to be noted that while the variable ratio drive system 10 is illustrated and described herein as replacing the front sprocket of a bicycle drive system, the general principles of the present invention could as well be designed as a rear sprocket cluster replacement or as a replacement of virtually any sprocket clusters for other applications.
The system 10 generally includes a variable diameter sprocket 12 and a sprocket diameter changing mechanism 14.
Figure 2 is a rear elevational view of the variable diameter sprocket of the variable ratio drive system of Figure 1;
Figure 3 is a sectional view taken along line 3-3 of Figure 1; and Figure 4 is a schematic view illustrating the operation of the sprocket diameter changing mechanism.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning now to Figures 1-3 of the appended drawings a variable ration drive system 10 according to an embodiment of the present invention will be described.
It is to be noted that while the variable ratio drive system 10 is illustrated and described herein as replacing the front sprocket of a bicycle drive system, the general principles of the present invention could as well be designed as a rear sprocket cluster replacement or as a replacement of virtually any sprocket clusters for other applications.
The system 10 generally includes a variable diameter sprocket 12 and a sprocket diameter changing mechanism 14.
The variable diameter sprocket 12, better seen from Figure 2, is configured and sized to be mounted to a conventional shaft 15 of a bicycle (shown in dashed lines in the figures) via a mounting sleeve 17. The variable diameter sprocket 12 is provided with a support 16 including a central portion 18, a peripheral portion 20 and six (6) radial branches 22a-22f extending from the central portion to the peripheral portion in a symmetrical fashion. The branches 22a-22f are defined by identical cutouts 24a-24f. The variable drive sprocket 12 also includes six sprocket portions 26a-26f mounted to a respective branch 22a-22f of the support 16.
For concision purposes and since the variable diameter sprocket 12 is symmetrical, only branch 22a and its respective sprocket portion 26a will be described in greater details hereinbelow.
Branch 22a includes a radial channel 28a and five (5) radially aligned circular apertures 30, 32, 34) 36 and 38 provided in the radial channel 28a.
The sprocket portion 26a includes a dented portion 40, a channel engaging portion 42, better seen in Figure 3, integrally formed with the dented portion 40 and provided with an internally threaded aperture 44, a threaded pin 46 engaged to the aperture 44, including a pan head 47, and configured and sized to enter any of the apertures 30-38 and a spring 48 fixedly mounted to the shaft 15 and slidably mounted to an aperture 50 of the pin 46.
The width of the channel engaging portion 42 is slightly smaller than the width of the channel 28a allowing the sprocket portion 26a to be radially and laterally moved therein. When a sufficient lateral movement of the sprocket portion 26a is obtained, the pin 46 will egress 5 the aperture in which it is inserted (aperture 32 in Figures 1-3) and radial movement of the sprocket portion 26a will be possible.
The direction of the force applied by the spring 48 (see arrow 52 in Figure 3) maintain the pin 46 in one of the apertures 30-38 unless an external force is applied as will be described hereinafter.
Turning now more specifically to Figure 3 of the appended drawings, the sprocket diameter changing mechanism 14 includes a fixed assembly 54 fixedly mounted to the bicycle and a movable assembly 56 so mounted to the fixed assembly 54 as to be longitudinally movable (see double-arrow 58).
The fixed assembly 54 includes a bracket 60 mounted to the bicycle via a plate 62 and a fastener 64. The bracket 60 includes a longitudinal slot 66 to which the movable assembly 56 may be mounted.
The movable assembly 56 includes a support 68 slidably mounted to said slot 66 via a fastener 70, a first angled abutting element 72 and a second angled abutting element 74. As will be described hereinafter in greater details, the first angled abutting element 72 has the function to selectively reduce the diameter of the variable diameter sprocket 12 while the second angled abutting element 74 has the function to selectively increase the diameter of the variable diameter sprocket 12.
For concision purposes and since the variable diameter sprocket 12 is symmetrical, only branch 22a and its respective sprocket portion 26a will be described in greater details hereinbelow.
Branch 22a includes a radial channel 28a and five (5) radially aligned circular apertures 30, 32, 34) 36 and 38 provided in the radial channel 28a.
The sprocket portion 26a includes a dented portion 40, a channel engaging portion 42, better seen in Figure 3, integrally formed with the dented portion 40 and provided with an internally threaded aperture 44, a threaded pin 46 engaged to the aperture 44, including a pan head 47, and configured and sized to enter any of the apertures 30-38 and a spring 48 fixedly mounted to the shaft 15 and slidably mounted to an aperture 50 of the pin 46.
The width of the channel engaging portion 42 is slightly smaller than the width of the channel 28a allowing the sprocket portion 26a to be radially and laterally moved therein. When a sufficient lateral movement of the sprocket portion 26a is obtained, the pin 46 will egress 5 the aperture in which it is inserted (aperture 32 in Figures 1-3) and radial movement of the sprocket portion 26a will be possible.
The direction of the force applied by the spring 48 (see arrow 52 in Figure 3) maintain the pin 46 in one of the apertures 30-38 unless an external force is applied as will be described hereinafter.
Turning now more specifically to Figure 3 of the appended drawings, the sprocket diameter changing mechanism 14 includes a fixed assembly 54 fixedly mounted to the bicycle and a movable assembly 56 so mounted to the fixed assembly 54 as to be longitudinally movable (see double-arrow 58).
The fixed assembly 54 includes a bracket 60 mounted to the bicycle via a plate 62 and a fastener 64. The bracket 60 includes a longitudinal slot 66 to which the movable assembly 56 may be mounted.
The movable assembly 56 includes a support 68 slidably mounted to said slot 66 via a fastener 70, a first angled abutting element 72 and a second angled abutting element 74. As will be described hereinafter in greater details, the first angled abutting element 72 has the function to selectively reduce the diameter of the variable diameter sprocket 12 while the second angled abutting element 74 has the function to selectively increase the diameter of the variable diameter sprocket 12.
The first and second angled abutting elements 72 and 74 respectively include bevels 76, 78 having angles similar to the angle of the pan head 47 of the pin 46. The distance between the first and second angled abutting elements 72 and 74 is slightly larger than the width of the pin 46, therefore allowing the pin to thread between the first and second angled abutting elements 72 and 74 when the pin 46 is correctly positioned for the desired diameter of the variable diameter sprocket 12.
Of course, as will be easily understood by one skilled in the art upon reading the following description of the operation of the sprocket diameter changing mechanism 14, the sprocket diameter changing mechanism 14 also includes means (not shown), fixedly mounted to the fixed assembly 54 to move the movable assembly 56 (see double arrow 58) upon user's control, as will be described hereinbelow.
It is also to be noted that if variable diameter sprockets according to the present invention are used to replace the front and rear sprocket clusters of a bicycle, the movable assembly moving means (not shown) could be linked to provide a single user's operable lever to actuate both sprocket diameter changing mechanisms.
Turning now to Figure 4 of the appended drawings, the operation of the variable diameter sprocket 12 will now be described.
It is to be noted that, in Figure 4, branch 22a is illustrated twice in different positions as the sprocket 16 is rotated (see arrow 80). More specifically, Figure 4 illustrates the sprocket portion 26a as it is moved from the second aperture 32 of the channel 28a to the third aperture 34 of the same channel.
To cause the movement of the sprocket portion 26a, the movable assembly 56 of the sprocket diameter changing mechanism 14 is moved outwardly (see arrow 82). This movement will place the second angled abutting element 74 in the path of the rotating pin 46 of the sprocket portion 26a. The head 47 will therefore contact the bevel 78 of the second angled abutting element 74. Because of the physical relationship between the sprocket diameter changing mechanism 14 and the variable diameter sprocket 12 this contact will laterally move the sprocket portion 26a so that the pin 46 egress the aperture 32. The angle of the abutting element 74 will then radially move the sprocket portion 26a inside its channel 28a. When the position of the variable diameter sprocket 12 is such that the head 47 no longer contacts the abutting element 74, the sprocket portion 26a is then moved back laterally causing the pin 46 to enter the aperture 34, completing the displacement of the sprocket portion 26a.
Of course, as will be easily understood by one skilled in the art, upon a full rotation of the variable diameter sprocket 12, the six sprocket portions 26a-26f will be moved from the aperture 32 to the aperture 34 of their respective channels 28a-28f.
It is also to be noted that if the sprocket portions 26a-26f were to be moved from the aperture 34 to the aperture 32, for example, the first angled abutting element 72 would be the element contacting the head 47 of the sprocket portions in a similar fashion to lift, move and finally release the sprocket portions.
It is also believed within the skills of one skilled in the art to design a similar variable diameter sprocket where the sprocket portions would be only movable radially in their respective channel and where the pin 46 would not be fixedly mounted to the sprocket portions but would be slidably inserted therein to provide the lateral movement.
Although the present invention has been described hereinabove by way of preferred embodiments thereof, it can be modified, without departing from the spirit and nature of the subject invention as defined in the appended claims.
Of course, as will be easily understood by one skilled in the art upon reading the following description of the operation of the sprocket diameter changing mechanism 14, the sprocket diameter changing mechanism 14 also includes means (not shown), fixedly mounted to the fixed assembly 54 to move the movable assembly 56 (see double arrow 58) upon user's control, as will be described hereinbelow.
It is also to be noted that if variable diameter sprockets according to the present invention are used to replace the front and rear sprocket clusters of a bicycle, the movable assembly moving means (not shown) could be linked to provide a single user's operable lever to actuate both sprocket diameter changing mechanisms.
Turning now to Figure 4 of the appended drawings, the operation of the variable diameter sprocket 12 will now be described.
It is to be noted that, in Figure 4, branch 22a is illustrated twice in different positions as the sprocket 16 is rotated (see arrow 80). More specifically, Figure 4 illustrates the sprocket portion 26a as it is moved from the second aperture 32 of the channel 28a to the third aperture 34 of the same channel.
To cause the movement of the sprocket portion 26a, the movable assembly 56 of the sprocket diameter changing mechanism 14 is moved outwardly (see arrow 82). This movement will place the second angled abutting element 74 in the path of the rotating pin 46 of the sprocket portion 26a. The head 47 will therefore contact the bevel 78 of the second angled abutting element 74. Because of the physical relationship between the sprocket diameter changing mechanism 14 and the variable diameter sprocket 12 this contact will laterally move the sprocket portion 26a so that the pin 46 egress the aperture 32. The angle of the abutting element 74 will then radially move the sprocket portion 26a inside its channel 28a. When the position of the variable diameter sprocket 12 is such that the head 47 no longer contacts the abutting element 74, the sprocket portion 26a is then moved back laterally causing the pin 46 to enter the aperture 34, completing the displacement of the sprocket portion 26a.
Of course, as will be easily understood by one skilled in the art, upon a full rotation of the variable diameter sprocket 12, the six sprocket portions 26a-26f will be moved from the aperture 32 to the aperture 34 of their respective channels 28a-28f.
It is also to be noted that if the sprocket portions 26a-26f were to be moved from the aperture 34 to the aperture 32, for example, the first angled abutting element 72 would be the element contacting the head 47 of the sprocket portions in a similar fashion to lift, move and finally release the sprocket portions.
It is also believed within the skills of one skilled in the art to design a similar variable diameter sprocket where the sprocket portions would be only movable radially in their respective channel and where the pin 46 would not be fixedly mounted to the sprocket portions but would be slidably inserted therein to provide the lateral movement.
Although the present invention has been described hereinabove by way of preferred embodiments thereof, it can be modified, without departing from the spirit and nature of the subject invention as defined in the appended claims.
Claims
1. A variable diameter drive system including:
a variable diameter sprocket including:
a support having a generally circular shape, a rotation axis and at least three radial channels each provided with at least two apertures;
at least three sprocket portions, each being so mounted to a respective radial channel of said support as to be radially movable therein; each of said at least three sprocket portions including a projection configured and sized to enter one of said at least two apertures; and biasing means biasing said projection towards said at least two apertures;
sprocket diameter changing mechanism including:
a fixed portion; and a movable portion so mounted to said fixed portion as to be linearly movable; said movable portion including means for pulling said projection from one of said apertures, repositioning said sprocket portion and replacing said projection in the other of said apertures.
a variable diameter sprocket including:
a support having a generally circular shape, a rotation axis and at least three radial channels each provided with at least two apertures;
at least three sprocket portions, each being so mounted to a respective radial channel of said support as to be radially movable therein; each of said at least three sprocket portions including a projection configured and sized to enter one of said at least two apertures; and biasing means biasing said projection towards said at least two apertures;
sprocket diameter changing mechanism including:
a fixed portion; and a movable portion so mounted to said fixed portion as to be linearly movable; said movable portion including means for pulling said projection from one of said apertures, repositioning said sprocket portion and replacing said projection in the other of said apertures.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2230426 CA2230426A1 (en) | 1998-02-25 | 1998-02-25 | Variable ratio drive system |
| AU32421/99A AU3242199A (en) | 1998-02-25 | 1999-02-25 | Variable ratio drive system |
| PCT/CA1999/000170 WO1999043539A1 (en) | 1998-02-25 | 1999-02-25 | Variable ratio drive system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2230426 CA2230426A1 (en) | 1998-02-25 | 1998-02-25 | Variable ratio drive system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2230426A1 true CA2230426A1 (en) | 1999-08-25 |
Family
ID=4162152
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2230426 Abandoned CA2230426A1 (en) | 1998-02-25 | 1998-02-25 | Variable ratio drive system |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU3242199A (en) |
| CA (1) | CA2230426A1 (en) |
| WO (1) | WO1999043539A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6332852B1 (en) * | 2000-05-30 | 2001-12-25 | 3561020 Canada Inc. | Variable ratio drive system |
| WO2007037747A1 (en) * | 2005-09-29 | 2007-04-05 | Infinigear Ab | Gear assembly and constinuously variable transmission comprising such gear assembly |
| KR101172345B1 (en) * | 2012-06-01 | 2012-08-14 | 한휴 | Auto Trans Device For Bicycle |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR960014A (en) * | 1950-04-12 | |||
| US4030373A (en) | 1975-11-20 | 1977-06-21 | B-5 Associates Of Stamford, Connecticut | Variable speed drive for a bicycle |
| WO1979000522A1 (en) * | 1978-01-18 | 1979-08-09 | R Williams | Drive system |
| DE3214925A1 (en) * | 1981-02-26 | 1983-10-27 | Hans-Joachim 5060 Bergisch Gladbach Müller | Chain or belt drive |
| DE3107255A1 (en) * | 1981-02-26 | 1982-09-02 | Hans-Joachim 5060 Bergisch Gladbach Müller | Chain or belt drive |
| US4854925A (en) * | 1987-11-06 | 1989-08-08 | Gmi Engrg., & Mgmt., Institute | Multi-ratio drive system for sprockets having translating pins |
| US4832660A (en) | 1988-07-11 | 1989-05-23 | Leonard George H | Variable ratio drive mechanism |
| US5013284A (en) | 1990-03-26 | 1991-05-07 | Hamlin Transmission Corporation | Variable ratio drive system |
| US5094653A (en) | 1990-03-26 | 1992-03-10 | Hamlin Transmission Corporation | Belt drive apparatus |
| US5104357A (en) | 1990-03-26 | 1992-04-14 | Hamlin Transmission Corporation | Variable ratio drive system |
| US5041061A (en) | 1990-03-26 | 1991-08-20 | Hamlin Transmission Corporation | Variable ratio drive system |
-
1998
- 1998-02-25 CA CA 2230426 patent/CA2230426A1/en not_active Abandoned
-
1999
- 1999-02-25 AU AU32421/99A patent/AU3242199A/en not_active Abandoned
- 1999-02-25 WO PCT/CA1999/000170 patent/WO1999043539A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| AU3242199A (en) | 1999-09-15 |
| WO1999043539A1 (en) | 1999-09-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |