Guide unit for bicycle or motorcycle fork tube

Abstract

A guide unit (40) for a bicycle or motorcycle fork tube (10) having a longitudinal axis (A) and provided with two coaxial tubes (20) (30) together defining a cylindrical space (17), one of the two coaxial tubes being telescopically slidable along the axis (A) inside the other by means of an inserted guide unit, the guide unit in turn is provided with a pair of sliding bushes (41) (42) (42 ') interposed in the radial direction between the two coaxial tubes (20) (30) and spaced apart from each other in the axial direction inside the cylindrical space; each bushing has a respective rigid cylindrical body (43) (44) and a respective sliding liner (45) (46) made of a material having a low coefficient of friction and configured to be in contact with a respective coaxial tube; a plurality of lubricant reservoirs (50) are formed in the sliding liner and uniformly distributed over the respective bushings.

Description

Technical Field

[0001] This invention relates to a guide unit for bicycle or motorcycle fork tubes. Background Technology

[0002] The fork tube of a bicycle or motorcycle fork has a longitudinal axis and includes an outer lower stop and an inner hollow stent, which are coaxial with each other and with the longitudinal axis, and the stent can move inside the lower stop. This movement is achieved by a guide unit, which in its most well-known form includes two sliding bushings located between the stent and the lower stop and configured to be a given axial distance apart from each other.

[0003] Each bushing of the guide unit includes a steel cylindrical body and a sliding layer. The steel cylindrical body provides high mechanical strength to the bushing, and the sliding layer is typically made of a heat-resistant polymer configured to contact the cylindrical body, defining a cylindrical sliding surface to allow for better movement of the strut relative to the lower.

[0004] The bushing (especially the corresponding sliding layer) is further lubricated with oil, which completely fills the cavity of the strut and the lower part in which the strut slides. Summary of the Invention

[0005] The present invention aims to provide a guide unit for fork tubes that is lighter than conventional guide units, contributes to environmental sustainability by reducing the amount of oil used in the fork and optimizing bushing lubrication, and also helps to reduce friction between the bushing, lower stop and strut to improve the performance of the fork tube itself.

[0006] According to the invention, these objects and advantages, as well as other objects and advantages, are achieved by a guide unit for a fork tube having the features set forth in the appended claims. Attached Figure Description

[0007] The invention will now be described with reference to the accompanying drawings, which illustrate non-limiting exemplary embodiments of the invention, in which:

[0008] - Figure 1 This is a perspective view of a preferred embodiment of the guide unit for bicycle or motorcycle fork tubes according to the present invention, with parts removed for clarity;

[0009] - Figure 2 and Figure 3 yes Figure 1 A magnified view of the first detail of the guide unit in the image, with some parts removed for clarity;

[0010] - Figure 4 and Figure 5 yes Figure 1 A magnified view of the second detail of the guide unit in the image, with some parts removed for clarity; and

[0011] - Figure 6 It shows Figure 4 and Figure 5 Preferred alternative implementations of the details. Detailed Implementation

[0012] Reference Figure 1 The reference numeral 10 in the figure generally indicates the fork tube of a bicycle or motorcycle fork (known and not shown).

[0013] In typical use, the fork tube 10 is intended to form part of a bicycle or motorcycle fork, which includes two parallel fork tubes that can be connected to the steerer tube of the bicycle or motorcycle via a corresponding plate. The fork tube 10 has a longitudinal axis A and includes:

[0014] - Two coaxial tubes 20 and 30, one of which slides telescopically inside the other, referred to in the remainder of this specification as lower 20 and stention 30; and

[0015] - A guide unit 40 is placed between the lower stop 20 and the support column 30 to guide the support column 30 inside the lower stop 20, thereby allowing the support column 30 to move along axis A.

[0016] The lower stop 20 is defined by a tubular cylindrical body 21 having a circular opening 22 and being defined internally by a cylindrical surface 21a; while the support 30 is defined by a cylindrical tubular body 31 inserted into the body 21 through the circular opening 22 and defined externally by a cylindrical surface 31a facing the surface 21a. The surfaces 21a of the lower stop 20 and 31a of the support 30 face each other and together define a cylindrical space or chamber 17, which typically contains a certain amount of oil to minimize friction between the support 11 and the lower stop 12 when they slide relative to each other.

[0017] The guide unit 40 includes a pair of sliding bushings 41 and 42, which are radially positioned between the lower stop 20 and the support 30 with a tolerance smaller than that between the lower stop 20 and the support 30 themselves, and are axially spaced apart from each other within the cylindrical space 17.

[0018] Each bushing 41 and 42 includes cylindrical bodies 43 and 44 and sliding linings 45 and 46. The cylindrical bodies 43 and 44 are made of steel that imparts high mechanical strength to the respective bushings 41 and 42. The sliding linings 45 and 46 are made of a material with a low coefficient of friction (such as polytetrafluoroethylene) or a heat-resistant polymer and are configured to contact the respective cylindrical bodies 43 and 44 to define respective cylindrical sliding surfaces 45a and 46a.

[0019] exist Figure 1 In the exemplary embodiment of the invention shown, the bushing 41 is configured near the circular opening 22 and axially immobilized in the seat 23 formed in the lower section 20. The bushing 41 is internally slidably engaged with the support column 30, and as shown... Figure 2 and Figure 3 As better shown in the diagram, the bushing 41 has a liner 45, which is internally configured to have a surface 45a oriented radially toward the surface 31a of the support 30 and slidingly contacting the surface 31a of the support 30.

[0020] On the other hand, the bushing 42 is positioned near the distal portion 32 of the tubular cylindrical body 31, is axially immobilized to the body 31 itself, and slidably engages with the lower stop 20 externally. Figure 4 and Figure 5 As shown more clearly in the diagram, the lining 46 is disposed on the outside of the bushing 42, that is, a surface 46a having a cylindrical surface 21a oriented radially toward the lower stop 20 and in sliding contact with the cylindrical surface 21a of the lower stop 20.

[0021] Bushings 41 and 42 have different corresponding axial heights H1 and H2, where height H1 is greater than height H2. The two bushings 41 and 42 precisely perform similar but not identical tasks by means of their axial positioning along axis A within the cylindrical space 17. Bushings 41 and 42 (particularly the corresponding sliding liners 45 and 46) are further lubricated by oil within the cylindrical space 17. However, to reduce the amount of oil used in the fork tube 10 and to optimize the lubrication of bushings 41 and 42 themselves, bushings 41 and 42 are provided with multiple lubricant reservoirs 50 formed in the respective sliding liners 45 and 46 and evenly distributed on the corresponding sliding surfaces 45a and 46a.

[0022] Preferably, such as Figures 2 to 5As shown, the lubricant reservoir 50 is formed through the sliding liners 45 and 46 and is defined by a blind bottom cavity, which is preferably, but not necessarily, circular and distributed in a quincunx arrangement. This arrangement and shape of the blind bottom cavity can vary depending on the application requirements, i.e., depending on the size of the fork tube 10.

[0023] By using non-restrictive examples, Figure 6 A bushing 42', identical in appearance to the bushing 42 described above, is shown. The difference is that the lubricant reservoir 50 is defined by elongated blind cavities along corresponding rows of the cylindrical body 44, and is also arranged in columns circumferentially, with each column of lubricant reservoirs 50 configured to be equidistant from the others in the same column. The same distribution can also be applied to bushing 41 and its liner 45, and the guide unit 40 itself can couple bushings with five-point reservoirs to bushings with column-arranged reservoirs, and the circular reservoirs 50 can be organized in rows and columns.

[0024] The distinguishing feature of these lubricant reservoirs 50 is that they accumulate lubricant that may be released when there is insufficient lubricant in the cylindrical space 17, and they reduce friction between sliding surfaces 45a and 46a and surfaces 21a and 31a due to the increased amount of lubricant available, and again precisely because of the increased amount of lubricant available, they prevent potential seizing between surfaces 45a and 46a and surfaces 21a and 31a. Furthermore, first and foremost, the reservoirs 50 formed through the lining layers 45 and 46 have a further beneficial effect on reducing friction because they effectively reduce the size of the sliding surfaces 45a and 46a, i.e., the surface area in contact with each other.

[0025] It should be understood that the present invention is not limited to the embodiments described and shown herein, which are considered exemplary embodiments of the guide unit for a fork tube of a bicycle or motorcycle fork, and variations may be made in the form and configuration of the components, structural and functional details, and the materials used. For example, the invention can be applied equally to upside-down (USD, i.e., inverted strut) fork tubes and conventional fork tubes. It will also be clear that the invention can be used with single-sided telescopic hydraulic forks. The invention can also be implemented with sliding and / or rotating forks. The invention should be understood to cover all variations within the scope of the invention as defined by the appended claims.

Claims

1. A guide unit (40) for a fork tube (10) of a bicycle or motorcycle fork, the fork tube (10) having a longitudinal axis (A) and comprising two coaxial tubes (20)(30) defining a cylindrical space (17) between the two coaxial tubes (20)(30), and the two coaxial tubes (20)(30) being telescopically slidable, one tube inside the other tube, along the axis (A) by means of an inserted guide unit (40), the guide unit (40) further comprising a pair of sliding bushings (41)(42)(44). 2'), the pair of sliding bushings (41)(42)(42') are radially located between the two coaxial tubes (20)(30) and axially spaced apart from each other within the cylindrical space (17); each bushing (41)(42)(42') comprises a corresponding rigid cylindrical body (43)(44) and a corresponding sliding liner (45)(46), the sliding liner (45)(46) being made of a low coefficient of friction material and configured to contact the associated coaxial tube (20)(30); characterized in that, The guide unit (40) also includes a plurality of lubricant reservoirs (50) formed in the sliding liner (45)(46) and evenly distributed on the associated bushings (41)(42)(42').

2. The guiding unit according to claim 1, characterized in that, The lubricant reservoir (50) is formed by the sliding liner (45)(46) and is defined by a blind bottom cavity.

3. The guiding unit according to claim 2, characterized in that, The lubricant storage section (50) is circular in shape.

4. The guiding unit according to claim 3, characterized in that, The lubricant storage section (50) is elongated in shape.

5. The guiding unit according to claim 3 or 4, characterized in that, The lubricant storage compartments (50) are arranged in a five-point pattern.

6. The guiding unit according to claim 3 or 4, characterized in that, The lubricant reservoirs (50) are distributed along the corresponding rows of the bushings (41)(42)(42') and also along columns that are equidistant in the circumferential direction, wherein the lubricant reservoirs (50) of each column are equidistant from the lubricant reservoirs (50) of the same column in the axial direction.

7. The guiding unit according to any one of the preceding claims, characterized in that, Each bushing (41)(42)(42') includes a cylindrical body (43)(44) and a sliding liner (45)(46), the cylindrical body (43)(44) being made of steel to provide high mechanical resistance to the bushing (41)(42)(42') itself, and the sliding liner (45)(46) being made of a low coefficient of friction material, which is a heat-resistant polymer.

8. A bicycle or motorcycle fork tube, comprising a guide unit according to any one of the preceding claims.

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