WO2010102349A1

WO2010102349A1 - Fork assemblies

Info

Publication number: WO2010102349A1
Application number: PCT/AU2010/000291
Authority: WO
Inventors: Alan Fetterplace
Original assignee: Alan Fetterplace
Priority date: 2009-03-13
Filing date: 2010-03-12
Publication date: 2010-09-16

Abstract

A front wheel assembly (1) for supporting a wheel attachment point (2), the assembly including a movable element (3) capable of retaining the wheel attachment point (2) coupled between a first end (4) and a second end (5) of a fork member (6) wherein the moveable element (3) is able to move relative to the fork member (6).

Description

Fork Assemblies

Technical Field

The invention generally relates to fork assemblies for supporting and adjusting the position of the wheels of vehicles. In particular, the fork assemblies are for use with two wheeled vehicles such as bicycles and motorcycles.

Background Art

There have been numerous systems designed to steer motorcycles. Most commonly, however, motor cycles have a telescopic front fork. Telescopic forks include two steering yokes and two downwardly extending spaced apart members which are received into corresponding housing boots. The ends of the corresponding members are slidable within the housing boots and are coupled to the housing boots via a spring and damper unit so that the members and housing boots form a suspension unit.

The housing boots further include a support point for receiving an axel on which a front wheel of the motorcycle may be attached. The suspension unit allows the wheel to move upwardly and downwardly providing the motorcycle with smooth passage over a ground surface.

In use, the steering yokes of the forks are coupled to the motor cycle frame via steering head bearings and the front wheel is seated on the axle. In this configuration, the distance between the front wheel axle and the steering head bearings acts as a moment arm about the steering head bearings which causes large forces and severe stress on the motorcycle frame, bearings and an associated upper portion of the forks.

A disadvantage of this configuration is that the motor cycle forks, bearings, frame and associated components typically need to be reinforced in the vicinity of the coupling between the steering yoke, forks and the frame to be resilient to the forces and stresses. Another disadvantage of this telescopic fork configuration is that the forces and stresses of the forks, bearings and frame inhibit the front wheel from being held rigidly in-line with the rear wheel.

In another aspect, the rear wheel of the motor cycle is often driven by a chain or belt connection between a gear of a motor housed by the frame and sprocket of the rear wheel drive assembly. Typically, the chain is coupled between the gear and sprocket via a rear swing arm which provides a pivotal connection between a frame of the motorcycle and the rear wheel drive assembly. The chain is required to be sufficiently tensioned so that the chain is retained on the gear and sprocket without over-tensioning which may cause friction and stress on the chain, gear and sprocket as well as associated components.

Accordingly, motorcycles often include a mechanism to adjust the tension of the rear drive chain. These mechanisms may include a series of discrete slots provided on the swing arm into which the rear wheel drive assembly may be secured. To tension the chain an axel associated with the rear wheel drive assembly may be moved within the series of slots, changing the distance between the gear and the sprocket, thereby allowing the tension of the chain to be adjusted.

A disadvantage of these types of chain adjustment mechanisms is that the discrete slots limit the adjustment range through which the rear wheel drive assembly may be moved.

Another disadvantage of these types of chain adjustment mechanisms is that the adjustment mechanism is not integral with the swing arm.

Summary of the Invention

In accordance with one broad aspect there is provided, a front wheel assembly for supporting a wheel attachment point, the assembly including a movable element capable of retaining the wheel attachment point coupled between a first and a second end of a fork member wherein the moveable element is able to move relative to the fork member.

In one form, the moveable element is slidable along the fork member between the first and the second ends.

In one form, the assembly includes a brace coupled to and extending outwardly from the second end.

In one form, the first end of the fork member is adapted to be coupled to a frame and the brace extends between the second end of the fork member and the frame so as to provide structural support between the fork member and the frame.

In one form, the brace includes an end coupled to the second end of the fork member and an opposing end adapted for slidable engagement with the frame to provide structural support to the second end.

In one form, the brace is configured to provide a pivotal coupling between the second end of the fork member and the frame.

In one form, the brace includes a pivotally coupled linkage.

In one form, an end of the brace is rigidly coupled to the second end of the fork member.

In one form, the brace includes a strut extending between the brace and the fork member so as to provide structural support to the brace.

In one form, the fork member includes two spaced apart stanchions between which a wheel may freely rotate when coupled to the wheel attachment point.

In one form, the brace forms a coupling between the stanchions. In one form, the brace is U shaped

In one form, the stanchions are joined by at least one yoke.

In one form, the yoke is coupled to the frame so that the assembly is movable relative to the frame.

In one form, the wheel attachment point includes an axel for supporting a wheel.

In one form, the movable element is coupled to the frame via a biasing element.

In one form, the movable element is coupled to the fork member via a biasing element thereby restraining the movement of the element relative to the fork member.

In one form, the biasing element is provided in the form of a suspension unit

In one form, the moveable element is provided by a tubular sleave slidable along the fork member between the first the second ends.

In accordance with another broad aspect there is provided, an assembly for use in adjusting a wheel attachment point relative to a frame, the assembly including a first member carrying the wheel attachment point and a second member configured for coupling to the frame wherein the first and second members are movably coupled so that the wheel attachment point is movable relative to the frame.

In one form, the first member and second member are provided in the form of concentric tubes such that the first and second members form a telescopic linkage between the frame and wheel attachment point.

In one form, the first member is provided by first fork with spaced apart tubes and the second member is provided by a second fork with corresponding spaced apart tubes. In one form, the first fork includes a first bridge spacing apart and joining in the tubes.

In one form, the second fork includes a second bridge spacing apart and joining the tubes.

In one form, the first and second bridge are correspondingly shaped thereby providing clearance to allow the first and second fork to be moved in to a retracted position where the first and second bridge are immediately adjacent each other.

In one form, at least one of the first and second members includes a mechanism for restraining the relative movement of the first and second members.

In one form, the mechanism includes spacing shims for adjusting the position of the first member relative to the second member.

In one form, the mechanism included threaded bores which receive corresponding fasteners to couple the first member in a fixed relation to the second member.

Brief description of the Figures

The invention is described, by way of non-limiting example only, by reference to the accompanying drawings, in which;

Figure 1 is a front view illustrating a motor cycle front fork;

Figure 2 is a side view illustrating the motorcycle front fork;

Figure 3 is a top view illustrating the brace adjacent a frame;

Figure 4 is a top view illustrating bearings between the brace and the frame; Figure 5 is a side view of illustrating the another example of the brace with pivotal couplings;

Figure 6 is a top view illustrating the brace with the pivotal couplings;

Figure 7 is a top view illustrating a steering yoke;

Figure 8 is a front view illustrating a fork brace;

Figure 9 is a top view of illustrating a first fork member of a rear fork assembly;

Figure 10 is a top view illustrating a second fork member of a rear fork assembly, which may be coupled to the first fork member of figure 9.

Figure 11 is a top view illustrating another example of first member with separate legs.

Figure 12 is a top view illustrating another example of the second fork member into which the legs of the first member of Figure 11 may be received.

Detailed description of the Figures and embodiments of the Invention

Figure 1 illustrates a front wheel assembly 1 for supporting a wheel attachment point 2, the assembly 1 including a movable element 3 capable of retaining the wheel attachment point 2 coupled between a first 4 and a second end 5 of a fork member 6 wherein the moveable element 3 is able to move relative to the fork member 6.

The fork members 3 are provided in the from of two spaced apart stanchions 7 between which a wheel (not shown) may freely rotate when coupled to the wheel attachment point 2. The stanchions 7 are held in a fixed relation by a bottom yoke 8 and a top yoke 9 between which a steering support 14 is fixed. A steering head 15 of a frame of a bike (not shown), for example a motor cycle frame, may be coupled to the steering support 14. The steering head 15 includes bearings (not shown) such that front wheel assembly 1 is rotatable about the axis of the steering support 14.

The moveable element 3 is, provided by spaced apart tubular sleaves 10 through which each of the stanchions 7 passes, the tubular sleave 10 being slidable along the stanchions 7 between the respective first ends 4 the second ends 5. The travel of the tubular sleaves 10 being restricted by length of the tubular sleaves 10 relative to the distance between the second ends 5 and the bottom yoke 8. In that respect, the bottom yoke 8 and second ends 5 provide stops 18 to retain the tubular sleaves 10 on the stanchions 7.

The moveable element 3 carries a bracket 11 with a bore 12 into which the wheel attachment point 2, which is provided in the form of an axel 13, may be inserted. A front wheel (not shown) of a motorbike or other two wheeled vehicle may then be attached to the axel 13. The upper portions of the tubular sleaves 10 are coupled by bridge 19 which has a lower mounting point 16 to which a suspension unit (not shown) may be attached. The suspension unit being coupled between the lower mounting point 16 and an upper mounting point 17 which may be on the frame or an upper position of the fork member 6 such as the steering support 14.

It may be appreciated that in this configuration the front wheel is provided with suspension that is able to move relative to the first end 4 and second end 5 of the stanchions which remain fixed in an axial direction relative to the steering head 15 of the frame. Furthermore, as the suspension unit may be carried by the frame, a layout such as this removes the weight from the steering head bearings, thus permitting easier steering control.

Referring now to Figure 2, a lower brace 21 extends between the second end 5 of the stanchions 7 of the fork member 6 and the frame 20 so as to provide structural support between the fork member 6 and the frame 20. The lower brace 21 includes a strut 22 extending between the lower brace 21 and the bottom yoke 8 so as to provide structural support to the lower brace 21. This additional strut 22 provides structural triangulation for the front wheel assembly 1 therefore providing additional rigidity. Lines 27 and 28 respectively indicate the steering axis and a line perpendicular to the steering axis.

It may be appreciated that second ends 5 provide the lower brace 21 a fixed position relative to the vertical steering axis 27 so as to maintain its position against the frame 20.

Figure 3 illustrates an example of the lower brace 21 rigidly coupled to the second end 5. The brace 21 is substantially U-shape with two legs 23 extending rearward to a convex section 25. The convex section 25 corresponds to a concave section 26 carried by the frame 20. The convex section 25 and concave sections are configured such that as the wheel assembly 1 is turned throughout its turning lock, there is always slidable engagement between respective faces 28 and 29 of the convex and concave sections. The faces 28 and 29 may be coated with a friction reducing material such as Teflon so that the faces may more freely slide. It is envisaged that the shaped convex section 25 and section 26 may be have a plan form geometry (as shown in Figure 3) which conforms to a select radial distance form the steering axis 27. It is also envisaged that the faces 28 and 29 may be configured to be parallel to the line perpendicular to the steering axis 27 (as shown in Figure 2).

It may be appreciated that iiυthis example, there is no direct coupling between the lower brace 21 and the frame 20. Accordingly, the lower brace 21 provides most support when the wheel attachment point 2 is forced in a rearward direction toward the frame. This situation arises, for example, when the motor cycle is braking.

Figure 4 illustrates a similar configuration of the lower brace 21 as illustrated in Figure 3. However, in this example, bearings 30 are provided coupled to the convex section 25. The bearings 30 are configured to engage with the concave surface 26 and rotate relative thereto such that the convex and concave surface are relatively slidable. It may also be appreciated that the bearings could be located on the concave surface 26 to achieve a similar result. Figures 5 and 6, illustrate another example of the brace 21. However, in the example, the lower brace 21 is configured to provide a pivotal coupled linkage 31 between the second end 5 and the frame 20. The linkage 31 includes rocker arms 29 extending between stanchion pivots 39 and steering pivots 32 which couple the arms 29 to a curved member 33. The curved member 33 includes a central support pivot 34 which is coupled to the frame 20 in line with the steering axis 27. The rocker arms 29 include end portions 35 which are aligned perpendicularly to the steering axis 27 which allows the pivots 32 seated in the end portions 35 to have an axis of rotation parallel to the steering axis. This allows the linkage 31 to freely pivot when the wheel assembly 1 is turned throughout its turning lock. The rocker arms 29 may be curved outwardly or bowed to accommodate clearance for movement of the front wheel (not shown).

The steering pivots 32 are spaced apart at a distance equal to the distance been the stanchion pivots 39 so as to form a parallelogram configuration. The perpendicular distance between the central support pivot 34 and the outer steering pivots 32, may be equal to the perpendicular distance between the steering axis 27, and the stanchion pivots

39. The outer steering pivots 32 and the stanchion pivots 39 may be positioned parallel to the central support pivot 34. Other configurations would create a trapezoidal layout. It may also be appreciated than any of the aforementioned pivots may be in the form of bearings.

Referring now to Figure 7, bottom yoke 8 which is substantially U-shaped and may have bores 37 into which the stanchions 7 may be inserted and secured and a central bore 38 into which the steering support 14 may be inserted and secured, the steering head 15 being concentrically coupled to the steering support 14. It may be appreciated that the U-shaped bottom yoke 8, provides a clearance space such the fork bridge 19 may rise up between the stanchions 7. This permits the lower steering head bearing (not shown) to be located as closely as possible to the axle 13.

Referring now to Figure 8, the fork bridge 19 is illustrated as having an arch like shape between two feet 36 into which the stanchions 7 may be inserted and secured. The lower mounting point 16 is also shown.

Figures 9 and 10 illustrate a rear fork assembly 50 for use in adjusting a wheel attachment point 51 relative to a frame (not shown), the assembly 50 including a first member 53 (illustrated in Figure 9) carrying the wheel attachment point 51 and a second member 54 (illustrated in Figure 10) configured for coupling to the frame (not shown). The second member 54 is configured to be received by the first member 53 forming a slidable coupling so that the wheel attachment point 51 is movable relative to a frame to which the assembly 50 may be coupled.

The first member 53 and second member 54 are respectively provided in the form of a first fork 55 and second fork 56 including concentric tubes 57 such that the first fork 55 and second fork 56 form a telescopic linkage between the frame and wheel attachment point 51.

Referring to Figure 9, the first fork has two spaced apart legs 60 rigidly coupled by a first bridge 61. Each leg 60 has wheel attachment points 51 at an end 62 in the form of bores configured to receive an axel of a rear wheel of a motor cycle (not shown). The bridge 61 includes housings 63 into which an opposing end 64 of each leg 60 is received and thereby coupled to the bridge 61.

Referring to Figure 10, the second fork 56 also includes spaced apart legs 66 which are able to be slidably received by the first fork 55 by inserting the ends 67 of the second fork 56 into the opposing ends 64 of the legs 60 of the first fork 55. The second fork also includes a bridge 68 with spaced apart housings 69, however, the housings extend upwardly on each side to provide a pivot mounting 71 to mount the second fork 56 hence the assembly 50 to a rear pivot point of a motorcycle (not shown).

The housing 69 of the second fork 56 includes threaded holes 70 which are able to receive a corresponding bolts (not shown) extending through holes 65 in the housings 63 of the first fork 55. The bolts retain' the first fork 55 and the second fork 56 in a fixed relation with shims (not shown), also supported by the bolts, located on or in each of the legs 66 of the second fork 56. The shims are made of varying sizes and may be inserted on the legs 66 to vary the spacing between the first fork 55 and the second fork 56. Accordingly, it may be appreciate that the housing, bolts and shims form a mechanism for restraining the relative movement of the first and second members.

When the first fork 55 and second fork are coupled together to form the assembly 50, it may be appreciated that the arch shape of the bridges 61 and 68 are corresponding so that the first fork 55 and second fork 56 may be moved close together thereby providing increased travel of the assembly 50.

Accordingly, in use, the assembly 50 may be used to tighten a chain or belt connection between a gear of a motor (not shown) house by the frame (not shown) pivoted at point 71 and sprocket of the rear wheel drive assembly (not shown) which is coupled to the wheel attachment point 51.

Figures 11 and 12 illustrate an alternative arrangement for the rear fork assembly 50 in which like numerals denote like parts. In this example, the first member 53 is provided by a pair of tubular legs 75 and the second member 54 is provided by in the form of a second fork 56 similar to that of the example shown in Figure 10. The difference with the arrangement of this example is that the legs 66 of the second fork 56 are configured to receive the legs 75 of the first member 53. Furthermore, the ends 76 of the legs 66 have boots 77 which have bores 79 though which studs 78 of the first member 53 are able to pass. The studs 78 extend upwardly from a supporting flange 80 of the first member 53. As such, the first member 53 and second member 54 may be coupled together by passing the studs 78 through the bores 19 and affixing a nut (not shown) onto the end of the stud thereby compressing the supporting flange 80 and boots 77 together and hence securing the assembly 50 together. Moreover, similarly to the example discussed in relation to Figures 9 and 10, spacing shims may be inserted and supported by the studs 78 between the supporting flange 80 and boots 77 to varying the length of the rear fork assembly 50. Advantageously, first member 53 and second member 54 may be moved toward or apart so that the distance between the driving gear of a motor and the driven sprocket may be continuously varied to provide the correct tension on the chain. Once the correct distance is achieved between the gear and the sprocket the shims are inserted and the bolts are tightened. This ensures the chain is not over-tensioned which may cause friction and stress on the chain, gear and sprocket as well as associated components. Furthermore, as the adjustment mechanism is variable a motor bike user may use different drive train components including sprockets, gears and chains.

Many modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

List of Parts

I . Front wheel assembly 2. Wheel attachment point

3. Movable element

4. First end

5. Second end

6. Fork member 7. Stanchion

8. Bottom yoke

9. Top yoke

10. Tubular sleave

I I. Bracket 12. Bore

13. Axel

14. Steering support

15. Steering head

16. Lower mounting point 17. Upper mounting point

18. Stops

19. Bridge

20. Frame 21. Brace 22. Strut 23. Legs

25. Convex section

26. Concave section

27. Steering axis 28. Axis perpendicular to steering axis 29. Rocker Arm 30. Bearings

31. Linkage

32. Pivots

33. Curved member 34. Frame pivot

35. End portion

36. Feet

37. Bores

38. Central bore 39. Stanchion pivots

40. Face of convex section

41. Face of concave section

50. Rear fork assembly

51. Wheel attachment point 53. First member

54. Second member

55. First fork

56. Second fork 60. Legs 61. Bridge

62. End

63. Housing

64. Opposing end

65. Holes 66. Legs

67. Ends

68. Bridge

69. Housing

70. Threaded holes 71. Pivot Mounting

75. Tubular Legs 76. Ends

77. Boots

78. Studs

80. Support flange

Claims

1. A front wheel assembly for supporting a wheel attachment point, the assembly including a movable element capable of retaining the wheel attachment point coupled between a first and a second end of a fork member wherein the moveable element is able to move relative to the fork member.

2. The assembly of claim 1, wherein the moveable element is slidable along the fork member between the first and the second ends.

3. The assembly of claim 2, further including a brace coupled to and extending outwardly from the second end.

4. The assembly of claim 3, wherein the first end of the fork member is adapted to be coupled to a frame and the brace extends between the second end of the fork member and the frame so as to provide structural support between the fork member and the frame.

5. The assembly of claim 4, wherein the brace includes an end coupled to the second end of the fork member and an opposing end adapted for slidable engagement with the frame to provide structure support to the second end.

6. The assembly of claim 4, wherein the brace is configured to provide a pivotal coupling between the second end of the fork member and the frame.

7. The assembly of claim 6, wherein the brace includes a pivotally coupled linkage.

8. The assembly of claims 3 to 7, wherein an end of the brace is rigidly coupled to the second end of the fork member.

9. The assembly of claims 3 to 8, wherein the brace includes a strut extending between the brace and the fork member so provide structural support to the brace.

10. The assembly of claims 3 to 9, wherein the fork member includes two spaced apart stanchions between which a wheel may freely rotate when coupled to the wheel attachment point.

11. The assembly of claim 10, wherein the brace forms a coupling between the stanchions.

12. The assembly of claim 11, wherein the brace is U shaped

13. The assembly of claims 11 to 12, wherein the stanchions are joined by at least one yoke.

14. The assembly of claim 13, wherein the yoke is coupled to the frame so that the assembly is movable relative to the frame.

15. The assembly of any of the previous claims, wherein the wheel attachment point includes an axel for supporting a wheel.

16. The assembly of any of the previous claims, wherein the movable element is coupled to the frame via a biasing element.

17. The assembly of any of the previous claims, wherein the movable element is coupled to the fork member via a biasing element thereby restraining the movement of the element relative to the fork member.

18. The assembly of the 16 or 17, wherein the biasing element is provided in the form of a suspension unit

19. The assembly of any of the previous claims, wherein the moveable element is provided by a tubular sleave slidable along the fork member between the first the second ends.

20. An assembly for use in adjusting a wheel attachment point relative to a frame, the assembly including a first member carrying the wheel attachment point and a second member configured for coupling to the frame wherein the first and second members are movably coupled so that the wheel attachment point is movable relative to the frame.

21. The assembly of claim 20, wherein the first member and second member are provided in the form of concentric tubes such that the first and second members form a telescopic linkage between the frame and wheel attachment point.

22. The assembly of claim 20 or 21, wherein the first member is provided by a first fork with spaced apart tubes and the second member is provide by a second fork with corresponding spaced apart tubes.

23. The assembly of claim 21, wherein the first fork includes a first bridge spacing apart and joining in the tubes.

24. The assembly of claim 21 or 22, wherein the second fork includes second bridge spacing apart and joining the tubes.

25. The assembly of claim 24, wherein the first and second bridge are correspondingly shaped thereby providing clearance to allow the first and second fork to be moved in to a retracted position wherein the first and second bridge are immediately adjacent each other.

26. The assembly of claim 25, wherein at least one of the first and second members includes a mechanism for restraining the relative movement of the first and second members.

27. The assembly of claim 26, wherein the mechanism includes spacing shims for adjusting the position of the first member relative to the second member.

28. The assembly of claim 26 or 27, wherein the mechanism includes threaded bores which receive corresponding fasteners to couple the first member in a fixed relation to the second member.

29. An assembly for supporting a wheel attachment point relative to a frame as substantially described herein with reference to the drawings and/or figures.

30. A assembly for use in adjusting a wheel attachment point relative to a frame as substantially described herein with reference to the drawings and/or figures.