Self aligning crank assembly and method

• US 6,173,982 B1
• Filed: 08/19/1998
• Issued: 01/16/2001
• Est. Priority Date: 08/19/1998
• Status: Expired due to Term

• Current Assignee: Westergard W. David
• Original Assignee: Westergard W. David
• Inventors: Westergard, W. David
• Primary Examiner(s): Schwartz, Christopher P.
• Assistant Examiner(s): BARTZ, CLIFFORD T
• Application Number:
  US09/136,269
• Time in Patent Office: 881 Days
• Field of Search: 280/250, 280/260, 280/261, 280/259, 474/77, 474/78, 474/101, 474/122, 474/155-157, 474/152, 474/160, 474/162
• US Class Current: 280/261
• CPC Class Codes: B62M 9/085 involving eccentrically mounted driving or driven wheel
• CPC Class Codes: B62M 9/14 the wheels being laterally shiftable

Abstract

An improved cycle transmission comprising 1) a freewheel cluster rotatably coupled to the rear wheel of a bicycle and in axial alignment with the rear wheel axle; 2) a crank assembly having one or more laterally moveable chain rings rotatably coupled to a front section of the bicycle frame and in axial alignment with the pedal axle; and 3) a drive chain entrained around both the freewheel and chain ring. In a first embodiment, the crank assembly comprises a single chain ring which is laterally moveable with respect to the cycle frame. Lateral movement of the chain ring occurs in direct response to changes in the position of the drive chain on the freewheel cluster. The lateral movement of the chain ring allows the drive chain to maintain itself within a single plane relative to the chosen freewheel sprocket, thereby eliminating lateral bias. Accordingly, with no lateral bias, the entire grouping of freewheel sprockets can be accessed with the single chain ring, which eliminates the need for a chainwheel derailleur and complex shift patterns, and simplifies the operation of the transmission. A dual chain ring embodiment of the moveable crank assembly and transmission is further described. Additionally, a simplified method of operating the improved transmission of the present invention is disclosed.

Claims

1. A cycle crank assembly comprising:

a central hub adapted to rotate about an axis and having at least two spokes;

a chain ring having at least one sprocket associated therewith, said chain ring being moveably attached to said spokes such that said chain ring and sprocket are capable of being laterally translated in a direction parallel to said axis with respect to said central hub, the orientation of said chain ring with respect to said axis not changing during said lateral translation.

2. The crank assembly of claim 1, wherein said central hub is rotatably mounted to a bicycle frame.

3. The crank assembly of claim 1, wherein said spokes are articulated and include at least one hinged joint.

4. The crank assembly of claim 1, wherein said moveable attachment comprises a tongue and recess arrangement.

5. The crank assembly of claim 1, wherein said moveable attachment comprises a slidable pin and slot arrangement.

6. The crank assembly of claim 1, wherein said sprocket is welded to said chain ring.

7. The crank assembly of claim 1, wherein said chain ring and sprocket are at least partially metallic in composition.

8. A cycle transmission comprising:

a crank assembly rotatably mounted on a cycle frame, said crank assembly having at least one chain ring, said chain ring being positioned in a parallel relation to a first plane and being moveable laterally with respect to said cycle frame, and wherein lateral movement of said chain ring occurs in a direction substantially perpendicular to said first plane;

a freewheel cluster assembly having at least two freewheels, said freewheel cluster assembly being rotatably coupled to said cycle frame, the rotational plane of said freewheel cluster assembly being substantially parallel to the rotational plane of said crank assembly; and

a drive chain coupling at least one of said freewheels to said at least one chain ring, whereby said drive chain transfers torque from said chain ring to said at least one freewheel, and whereby placement of the drive chain on said one of said freewheels maintains said chain ring in substantial lateral alignment with said at least one freewheel.

9. The cycle transmission of claim 8, wherein said crank assembly further comprises:

a central hub having at least two spokes;

a chain ring having at least one sprocket associated therewith, said chain ring being moveably attached to said spokes such that said chain ring and sprocket are laterally moveable with respect to said hub.

10. A bicycle comprising:

a frame;

a first wheel rotatably attached to said frame;

a second wheel rotatably attached to said frame in substantial alignment with said first wheel;

a transmission having;

a crank assembly rotatably mounted on said frame, said crank assembly having at least one chain ring, said chain ring being positioned in a parallel relation to a first plane and being moveable laterally with respect to said frame, and wherein lateral movement of said chain ring occurs in a direction substantially perpendicular to said first plane;

a freewheel cluster assembly having at least two freewheels, said freewheel cluster assembly being rotatably coupled to said frame, the rotational plane of said freewheel cluster assembly being substantially parallel to the rotational plane of said crank assembly; and

a drive chain coupling at least one of said freewheels to said at least one chain ring, whereby said drive chain transfers torque from said chain ring to said at least one freewheel, and whereby placement of the drive chain on said one of said freewheels maintains said chain ring in substantial lateral alignment with said at least one freewheel.

11. The bicycle of claim 10, wherein said freewheels are coupled to the rearmost wheel and said crank assembly is rotatably mounted within said frame forward of said freewheel cluster assembly.

12. A method of operating a bicycle transmission having a crank assembly with at least one laterally moveable chain ring and a freewheel cluster having at least a first and second freewheel, said method comprising:

providing a drive chain coupling said at least one chain ring to said first freewheel;

providing a mechanism for shifting said drive chain between said at least first and second freewheels;

rotating said crank assembly and chain ring;

shifting said drive chain from said first freewheel to said second freewheel, wherein said shifting induces a lateral movement in said chain ring to bring said chain ring into substantial lateral alignment with said second freewheel.

13. The method of claim 12, wherein said crank further comprises:

a central hub having at least two articulated spokes;

a chain ring having at least one sprocket associated therewith, said chain ring being moveably attached to said spokes such that said chain ring and sprocket are laterally moveable with respect to said hub.

14. The method of claim 12, wherein said mechanism for shifting said drive train is a derailleur.

15. The method of claim 12, wherein said crank assembly includes two chain rings of differing diameter.

16. A cycle transmission comprising:

a crank assembly rotatably mounted on a cycle frame, said assembly having at least one chain ring, said chain ring being moveable laterally with respect to said cycle frame;

a cassette assembly having at least two freewheels, said cassette assembly being rotatably coupled to said cycle frame, the rotational plane of said cassette assembly being in substantial alignment with the rotational plane of said crank assembly; and

a drive chain coupling at least one of said freewheels to said at least one chain ring, whereby said drive chain transfers torque from said chain ring to said at least one freewheel, and whereby placement of the drive chain on said one of said freewheels maintains said chain ring in substantial lateral alignment with said at least one freewheel.

17. A cycle crank assembly comprising:

a central hub having at least two spokes, said at least two spokes being articulated and including at least one hinged joint;

a chain ring having at least one sprocket associated therewith, said chain ring being moveably attached to said spokes such that said chain ring and sprocket are laterally moveable with respect to said hub.

18. The crank assembly of claim 17, wherein said sprocket is welded to said chain ring.

19. The crank assembly of claim 17, wherein said chain ring and sprocket are at least partially metallic in composition.

20. The crank assembly of claim 17, wherein said at least one hinged joint is spring loaded so as to induce said chain ring to return laterally to a first position when no force is applied thereto.

21. A cycle crank assembly comprising:

a central hub having at least two spokes;

a chain ring having at least one sprocket associated therewith, said chain ring being moveably attached using a tongue and recess arrangement to said spokes such that said chain ring and sprocket are laterally moveable with respect to said hub.

22. The crank assembly of claim 21, wherein said at least two spokes are articulated and each include at least one hinged joint.

23. A cycle crank assembly comprising:

a central hub having at least two spokes, said at least two spokes being articulated and including at least one hinged joint;

a chain ring having at least one sprocket associated therewith, said chain ring being moveably attached to said spokes using a slidable pin and slot arrangement such that said chain ring and sprocket are laterally moveable with respect to said hub.

24. The crank assembly of claim 23, wherein said at least two spokes are articulated and each include at least one hinged joint.