EP2252498A1

EP2252498A1 - Suspension fork seal

Info

Publication number: EP2252498A1
Application number: EP09709924A
Authority: EP
Inventors: Stephan Kotzlowski
Original assignee: Albrecht Stephen; Felsl Andreas
Current assignee: B-Labs AG
Priority date: 2008-02-15
Filing date: 2009-02-16
Publication date: 2010-11-24
Also published as: US20110042915A1; WO2009100718A1; DE102008009426A1; US8342554B2

Abstract

The invention relates to a suspension fork for a bicycle, particularly a mountain bike, having at least one wishbone (2, 4) having a frame-side stanchion (6) whereon a sliding tube (8) is displaceably guided in segments by means of a bearing arrangement (20, 22), wherein the sliding tube (8) is sealed by means of a seal (38) sealingly contacting the outer circumference of the stanchion, wherein a volume of lubricant (42) formed in a ring gap between the sliding tube (8) and the stanchion (6) and limited on the front side at one end by the seal (38) and at the other end by an inner seal (28), wherein the ring gap can be accessed by at least one filling connection (44, 46).

Description

FORK SEAL

The invention relates to a suspension fork for a bicycle, in particular for a mountain bike, according to the preamble of claim 1.

Most two-wheelers, especially motorcycles and mountain bikes, use forks to guide the front wheel on a frame. The basic structure of such suspension forks is described for example under http://de.wikipedia.org/wiki/federgabel. Such suspension forks usually have two fork legs, each with a respect to the frame fixed standpipe and a hub of the front wheel bearing sliding tube. In so-called Upside Down suspension forks, the thinner sliding tubes each carry a dropout to which the hub is attached. These sliding tubes dive into the substantially larger diameter running tubes, which are connected via a, in most cases two triple clamps with the steering shaft tube. Such Upside Down Forks are commonly used on motorcycles. The most common design of mountain bikes are so-called RightSideUp suspension forks, in which the thinner standpipes are connected to the fork bridge (s) and into which the hub-bearing sliding or dip tubes dip.

The known suspension forks have steel springs, elastomeric suspensions and or air suspensions, each associated with a damping. In most applications, a hydraulic damping is provided, wherein, for example, in the case of a RightSideUp suspension fork, an open oil reservoir is formed in the hub-side, comparatively thick sliding tube. In the axial displacement of this sliding tube with respect to the standpipe fixed relative thereto, the resulting reduction of a part of the oil receiving pressure chamber, oil displaced from this and displaced via a valve, such as an adjustable throttle opening in another pressure chamber, so that a damping the suspension takes place.

The mounting of the sliding tube on the standpipe is usually carried out via two mutually spaced bearing bushes, with the greatest possible distance is sought in order to improve the rigidity of the suspension fork. The sealing of the oil reservoir receiving the interior of the sliding tube via a seal,

BESTATIGUNGSKOPIE also called scraper ring, which is inserted into the standpipe-side annular end face of the sliding tube and sealingly abuts the outer periphery of the thinner standpipe.

A problem with such constructions is that the overhead plain bearing and a wiper ring to retain the outside entering dirt to supply sufficient oil, so that the fork has a good response even in harsh conditions. In other words, it must be ensured that from the above-mentioned scraper ring downwards always a sufficient sliding film is formed on the guided in the sliding tube standpipe. This is particularly important in view of the temperature-changing viscosity of the oil, since it is very difficult, for example, in winter at low temperatures, to form the above-described lubricating film in the region of the upper plain bearing. In case of strong temperature differences, it may even be necessary to replace the oil depending on the application. For proper operation of the suspension fork, it is important that the predetermined level of the damper assembly is maintained - often is filled with a refill too much oil, so that then the sealing elements are damaged accordingly. In case of lack of lubrication, it may happen that the above-mentioned scraper is lifted and thus dirt penetrates into the region of the sliding, so that the response of the fork can no longer meet the requirements.

In contrast, the present invention seeks to provide a front fork, in which even under unfavorable conditions, a sufficient easy-to-use lubrication is ensured.

This object is achieved by a fork with the features of claim 1.

According to the invention, the fork provided for a bicycle, in particular for a mountain bike, has at least one fork leg, which has a standpipe supported on the frame, on which a slide arrangement carrying a hub is displaceably guided via a bearing arrangement. The seal between the sliding tube and the standpipe is made by a seal. According to the invention, the suspension fork is designed with a lubricant volume which is delimited in the radial direction by the inner circumferential wall of the sliding tube and by the outer peripheral wall of the standpipe on the one side by the seal and on the other hand by an inner seal. For filling the lubricant volume, the suspension fork is provided with a filling connection which opens preferably in the region of the inner seal and, in one variant, another, arranged in the region of the upper seal overflow port, so that a complete filling and emptying of this lubricant volume is ensured.

About this volume of lubricant is always ensured that in the area of the bearing assembly on the outer circumference of the standpipe, a sufficient lubricating film can form, so that the response of the fork even under difficult environmental conditions, for example, in large temperature differences and even when driving through heavy soil and mud, with appropriate Pollution of the suspension components remains virtually unchanged.

The lubricant volume, which preferably has nothing to do with the oil reservoir of hydraulic forks, opens up the possibility of using different oils optimized for the damping and for the oil volume with regard to the respective application (damping / lubrication).

In a preferred embodiment of the invention, the bearing assembly has two axially spaced bearing bushes. In this case, in one variant, the inner direction may be arranged to limit the lubricant volume between the bearing bushes, so that a lubrication in the region of the upper bearing bush is guaranteed by the lubricant volume.

In an alternative solution, the volume of lubricant in the axial direction may extend beyond the second, lower bushing out to the hub.

The arranged within the lubricant volume bearing bush preferably has a plurality of inner longitudinal grooves, each of which form passage channels for the oil.

In order to enable a lateral distribution of the oil within the sliding bearing, these passageways are connected to each other in the circumferential direction.

The construction according to the invention can be used particularly well in suspension forks with spring travel adjustment, since in such conventional solutions the space for an associated damping of an oil reservoir is further limited and thus the lubrication problems described above occur increasingly.

Other advantageous developments of the invention are the subject of further subclaims. In the following, a preferred embodiment of the invention is explained in more detail with reference to schematic drawings. Show it:

Figure 1 is a view of a fork for a mountain bike;

Figure 2 is a sectional view through a fork leg of the fork of Figure 1 and

3 shows a sectional view of a bearing bush of the suspension fork according to FIG. 1 and FIG. 2.

Figure 1 shows an embodiment of a suspension fork for mountain bikes. Details of this suspension fork are available at www, bionicon.de, so that only the essential elements for understanding the invention are described here. Of course, the invention can also be used in other suspension fork constructions.

The suspension fork 1 has two fork legs 2, 4, each having a respect to the frame fixed standpipe 6, which dips into a sliding tube 8 with a larger diameter. It is therefore a so-called RightSideUp fork. The two uprights 6 are connected to each other via two spaced apart yokes 10, 12, which are clamped on the outer circumference of the uprights 6. The top in Figure 1 fork bridge 12 carries an adjustable handlebar stem 14. About the two fork bridges 10, 12 and a steering head shaft, not shown, and a headset, the suspension fork 1 is mounted on the steering or control head of the frame.

To increase the rigidity of the suspension fork 1 and the two lower sliding tubes 8 are connected to a bridge 16 which is slightly upwards, pulled towards the stanchions 6 to provide space for the front wheel. At the bottom in Figure 1 end portions of the sliding tube 8 each dropouts 18 are provided for receiving a front hub.

In the interior of the sliding tube 8 each have a spring element (elastomer, steel spring, air spring device) is arranged, which can be assigned a hydraulic damping. The oil reservoir of this hydraulic damping can also be accommodated in the sliding tube 8. In the illustrated embodiment, the suspension fork 1 is additionally designed with a spring travel adjustment. Figure 2 shows a simplified sectional view along the line AA in Figure 1, wherein the outer geometry of the sliding tube 8 is shown simplified.

As already stated above, the standpipe 6 designed with a comparatively smaller diameter plunges into the sliding tube 8 and is guided in this via a slide bearing arrangement with two bearing bushes 20, 22 which are arranged at an axial distance from each other, the structure of which will be described below. To accommodate these two bushings 20, 22, the inner circumferential wall 24 is stepped in the storage area, so that an annular shoulder 26 is formed on which the lower bearing bush 22 is supported in Figure 2. On the upper ring end face of the bearing bush 22 in FIG. 2, an inner seal 28 is seated, which is inserted into the widened part of the sliding tube 8. This inner seal 28 is in the illustrated embodiment of an outer O-ring 30, which surrounds a favorable in terms of dynamic loads X-ring 32. Instead of this arrangement can be used on a special injection-molded sealing ring. Subsequent to the inner seal 28, a spacer bushing 34 is inserted into the widened part of the sliding tube 8, but its inner diameter is greater than the outer diameter of the upright tube 6, so that an annular space 36 remains. On the upper end side of the spacer bushing 34, the second bearing bush 20 is located, which is held by a scraper 38 in contact with the spacer bushing 34. This scraper 38 is inserted into the end portion of the sliding tube 8 located at the top in FIG. 2 and has sealing lips 40 with which it rests sealingly against the outer circumference of the upright tube 6. By the scraper 38 and the inner seal 30, an additional lubricant volume 42 is limited in the axial direction and by the inner peripheral wall of the sliding tube 8 and the outer peripheral wall of the standpipe 6 in the radial direction, which also contains the above-described annular space 36. This additional volume may be filled with oil to ensure adequate lubrication of the upper bushing 20, which is within this additional lubricant volume 42.

For filling this additional lubricant volume 42, a filling connection 44 and an overflow connection 46 are formed in the circumferential wall of the sliding tube 8, into each of which a filling or overflow nipple can be inserted. In the illustrated embodiment, these ports 44, 46 are designed as bores, wherein the filling port 44 opens just above the inner seal 28 and the overflow port 46 just below the scraper 38 in the lubricant volume 42, so that ensures a reliable filling and complete draining of this oil is. Figure 3 shows the basic structure of the bearing bush 20, wherein for clarity, only one half is shown. Accordingly, the bearing bush 20 has on its inner peripheral wall a plurality of axially parallel passageways 44 which are distributed uniformly around the circumference. The bearing bush 20 is inserted with its outer peripheral surface 50 into the sliding tube 8, while the longitudinal surfaces 52 of the passageways 50 delimiting webs act as sliding surfaces for the standpipe 6.

At least on the scraper 38 facing annular end face of the bearing bush 20 four circumferentially distributed recesses 54 are provided, of which only three are visible in the illustration of FIG. In this appropriate projections of the scraper 38 can dip. At the inner peripheral edge of this annular end face a chamfer 56 is formed, which ensures that a cross-connection between the passageways 48 is made, so that the oil can be distributed in the transverse direction. This transverse distribution is supported by the recesses 54. In this way, it is ensured that a sufficient sliding film can always form in the contact area between the upper bearing bush 20 and the standpipe 6.

In the illustrated embodiment, the lower, hub-side bushing 22 is disposed outside of this additional volume of oil. In principle, however, the inner seal 28 could also be arranged below this bearing bush 22, so that it too is lubricated by the additional oil volume.

For the sake of simplicity, the lower bearing bush 22 is designed in the same way as the bearing bush 20 described in FIG.

The construction according to the invention ensures that the two bearing bushes 20, 22 can also be arranged with forks with spring travel adjustment at a maximum distance from each other and that the upper bearing bush 20 and the scraper 38 (he generates the most friction in the system) always sufficiently lubricated are so that the fork 1 maintains its predetermined response even in adverse environmental conditions, the oil filling can be changed very easily to ensure optimum lubrication at different temperatures and applications.

The construction according to the invention can in principle also be used in suspension forks, in which the sliding tube dips into the standpipe. Disclosed is a suspension fork for a bicycle with a fork leg, which has a frame-fixed standpipe, which is partially immersed in a sliding tube, wherein the leadership between sliding and standpipe via a bearing assembly. According to the invention, an additional lubricant volume is provided, via which a sufficient lubrication of the bearing arrangement is ensured.

LIST OF REFERENCES:

fork

Gabelbeiπ

wishbone

Stand upright

slide tube

crown

stem

bridge

dropout

bearing bush

inner circumferential wall

annular shoulder

inner seal

O-ring

X-ring

spacer bushing

annulus

scraper

sealing lips

lubricant volume

Filling

Overflow connection

Passageways

Outer circumferential surface

longitudinal surface

recesses

chamfer

Claims

claims

1. suspension fork for a bicycle, in particular a mountain bike, with at least one fork leg (2, 4), which has a frame-side standpipe (6) on which sections a sliding tube (8) via a bearing assembly (20, 22) is displaceably guided, wherein the sealing of the sliding tube (8) via a sealingly applied to the outer periphery of the standpipe seal (38), characterized by a lubricant volume (42) which is formed in an annular space between the sliding tube (8) and the standpipe (6) and the front side on the one hand by the seal (38) and on the other hand by an inner seal (28) is limited, wherein the annular space by at least one filling port (44, 46) is accessible.

2. Suspension fork according to claim 1, wherein the bearing assembly has two axially spaced bearing bushes (20, 22) and the inner seal (28) between the bearing bushes (20, 22) is arranged.

3. Fork according to claim 1, wherein the inner seal (28) below the bearing assembly (20, 22) is arranged.

4. Suspension fork according to one of the preceding claims, wherein the bearing bush (20, 22) has a plurality of inner longitudinal grooves, each forming a passage channel (50) for the lubricant.

5. suspension fork according to claim 4, wherein the passage channels (50) are interconnected in the circumferential direction.

6. Fork according to claim 5, wherein in the region of the passageways (50) the end face a chamfer (56) is formed.

7. Fork according to one of the preceding claims, wherein the filling port (44) in the region of the inner seal (28) opens and in the region of the seal (38) an overflow port (46) for filling the oil volume (42) is arranged.

8. Suspension fork according to one of the preceding claims, with two fork legs (2, 4) which are connected via at least one fork bridge (10, 12) with a steering head shaft.

9. fork according to one of the preceding claims, with a spring travel adjustment.

10. Suspension fork according to one of the preceding claims, with a hydraulic damping with an oil reservoir, which is separated from the lubricant volume.

11. Suspension fork according to claim 10, wherein the lubricant in the lubricant volume and in the oil reservoir is different.