Exterior Adjustable Suspension Precompression Fork Cap Mechanism for Two Wheeled Vehicles

The present invention relates in general to an adjustable suspension component, more particularly an externally adjustable precompression fork cap design for popular two wheeled vehicle suspension systems.

Traditional two wheeled vehicle suspension designs have for the most part utilized a fork cap that housed and retained internal components such as compression springs, internal valving and oil. There was no precompression adjustment offered. The fork cap spoken of is usually threaded into the top side of the fork closest to the handlebars. This design gained popularity because of its simplicity and low cost of manufacturing. However, as time went on, the suspension on two wheeled vehicles became more and more technical and the need for fine tuning became more and more apparent.

A significant improvement came when a shrader valve was included in the fork cap to allow the addition of air pressure in the suspension shock absorber column. This was found to be ineffective since air pressure build up during use must be released and no additional pressure was useful.

Another improvement came when an adjustable precompression screw was incorporated into the fork cap. This design does not have a widespread usage due to its high profile. This is a major disadvantage because it impedes handlebar mounting location and adjustment. It is used on street bikes but there is another disadvantage. Due to the adjustment hex rising up above the triple clamps to extremes at minimum precompression adjustment, the resulting exposed edges create a safety problem for the user in the event of an accident.

A similar improvement came when a cam activated externally adjustable cap was introduced. U.S. Pat. No. 3,984,119 to Okazima (1976) discloses this system which is cam activated with a handle or knob extending above top triple clamp that again impedes the handlebar mounting and adjustment along with having only limited adjustment positions due to the cam type design.

Another means of precompression adjustment does not necessarily involve a mechanism. It consists of partial disassembly of suspension system to facilitate addition or subtraction of spacers. Adding spacers increases precompression and removing spacers decreases suspension precompression. One major problem this creates is foreign particles such as dirt may enter the hydraulic dampening system of the suspension forks. Many two wheeled vehicles are ridden off road and dirt and dust is thrown up onto the externals of the suspension and thus can be allowed into internals if disassembled. This can cause a reduction in bearing life and possible interruption in passage of oil through valving. Another major problem with this method of adjustment is unless special machined spacers have some sort of alignment collar included, there is the possibility of the spacers becoming misaligned, impeding inner fork tube travel at full compression. This can cause deformation of inner tube and sticktion when suspension is compressed and decompressed.

The object of the present invention is to provide an externally adjustable, low profile, light weight, precompression adjuster for popular two wheeled vehicle suspension designs. It also retains current oil dampener adjuster mechanism if present, without limiting handlebar location and adjustment.

One feature of the present invention is the provision of a threaded outer housing adapted to fit inside upper tube and house precompression adjustment mechanism.

Another feature of the present invention is the provision of a threaded adjuster hub that allows damper rod to screw into and hydraulic dampening adjustment screw to be placed within. This feature allows unlimited adjustment between minimum precompression and maximum precompression adjustment in the range of 0 to 100 mm.

In accordance with this object of the present invention, retention of adjuster hub by way of hub retaining spanner that allows adjuster hub to be rotated without moving up or down. This feature allows a wide range of handlebar adjustment at any precompression setting and the low profile design minimizes any safety hazard.

In accordance with another feature of the present invention a spring collar adapted to fit inside outer housing engaging adjuster hub moves up or down when adjuster hub is turned.

In accordance with this object of the present invention the provision of a spring collar rotational stop eliminating rotation and allowing movement u or down longitudinally with shock absorber column.

In accordance with this feature of the present invention the provision of spring locator which retains spring in the center of suspension tube so it does not conflict with inner tube movement.

In accordance with another feature of the present invention a ball spring detent mechanism is provided to enable the user to count the number of revolutions adjuster hub is turned and will also act as a holding device to retain desired adjustment position.

These features and advantages will become more apparent upon perusal of the following specifications taken in conjunction with the accompanying drawings wherein similar characters of reference refer to similar parts in each of the several views.

FIG. 1 is a perspective view of a motorcycle incorporating telescopic front suspension and the present invention.

FIG. 2 is a perspective view of a motorcycle top triple clamp incorporating to portion of upper tubes and present invention.

FIG. 3 is a cross sectional view of the upper fork tube incorporating present invention.

FIG. 4 is a perspective view of present invention removed.

FIG. 5 is a perspective view of present invention with hand means of adjustment.

FIG. 6 is a perspective view of present invention incorporating jam nut as means of adjustment retention.

10 Adj. Precompression Cap Assembly

12 O-Ring Groove

14 Hub Retaining Spanner

16 Compression Spring

18 Outer Housing

20 Ball Bearing

22 O-Ring

24 O-Ring

26 Spring Collar

28 Adjuster Threads

30 Recessed Area

32 Spring Collar Rotational Stop

34 Main Compression Spring

38 Jam Nut

40 Upper Fork Tube

42 Hex Engagement Area

44 Spanner Engagements

46 Prior Art Hydraulic Dampener Adjuster Screw

48 Top Triple Clamp

50 Threaded Area of Damper Rod

52 Inner Thread for Damper Rod

54 Threaded Area of Outer Housing

56 Stop Engagement Area

58 Adjustment Hub

62 O-Ring Groove

64 Wrench Flats

66 Threaded Area of Spanner

68 Inner Bore

70 Landing

72 Motorcycle

74 Fork Assembly

78 Knob

84 Boss Section

86 Thread Engagement Area

88 Spring Locator

90 Air Pressure Release Screw

Referring now to the drawing in FIG. 1, there is an illustration of a motorcycle 72 provided with a telescoping fork assembly 74 incorporating present invention. Referring now to FIG. 2-4, an adjustable precompression cap 10 includes an outer housing 18 adapted to fit inside upper tube at threaded area 54. A hex engagement area 42 for means of turning adjustment hub is also provided. A hub retaining spanner 14 threads into the outer housing 18 at threaded area 66 of spanner. Spanner engagements 44 are included for means of turning spanner in assembly. Outer housing threads into upper fork tube 40 which is attached via top triple clamp 48 and includes an O ring oil seal groove 62 to house O ring 24 and wrench flats 64 are provided for assembly.

The adjustment hub 58 is provided with a boss section 84 housed by inner bore 68, the hub retaining spanner 14, and landing 70. Adjuster threads 28 are provided to engage with thread engagement area 86. The hex engagement area 42 is provided along with and inner thread 52 to accept threaded area of damper rod 50. Prior art dampener screw 46 is also provided. An O ring oil seat 22 is housed in O ring groove 12. Spring collar 26 is provided with a pin engagement area 56 and dowel pin 32 is pressed in outer housing 18 and extends into stop engagement area 56. A recessed area 30 is included along with the threaded engagement area 86.

A ball bearing 20 and compression spring 16 detent mechanism is provided in conjunction with the adjuster hub 58 and engages the outer housing at machined detent grooves.

Spring collar 26 interfaces with the compression spring 34 at spring locator 88. Spring locator 88 provides constant main compression spring concentricity with upper tube which is lost when using the spacer method of precompression adjustment. Air pressure release screw 90 is shown a means of evacuating pressure build up in fork shock absorber.

Now referring to FIG. 5, a knob 78 is shown that could be offered in replacement to the hex engagement area 42 for means of turning adjuster hub by hand.

Now referring to FIG. 6, jam nut 38 is shown that could take the place of ball and spring detent mechanism for means of retaining desired precompression setting.

Of course the present invention is not intended to be restricted to any particular form or arrangement or any specific embodiment disclosed herein, or any specific use, since the same may be modified in various particulars or relations without departing from the spirit or scope of the claimed invention hereinabove shown and described of which the apparatus is intended only for illustration and for disclosure on an operative embodiment and not to show all of the various forms or modification in which the invention might be embodied or operated.

The invention has been described in considerable detail in order to comply with the patent laws by providing full public disclosure of at least one of its forms. However, such detailed description is not intended in any way to limit the broad feature or principles of the invention, or the scope of patent monopoly to be granted.