Fork leg, telescopic fork and method for adjusting the length of a fork leg

Abstract

The invention relates to a fork leg, comprising an outer tube and an inner tube which extend along a longitudinal axis, wherein: the outer tube has at least one fastening portion for arranging a fork crown, and the outer tube comprises a first stop and a second stop, the first stop being designed to limit the insertion of the inner tube into the outer tube and the second stop being designed to limit its emergence; and the outer tube comprises an adjustment element by means of which the stops can be moved along the longitudinal axis in such a way that a maximum length of the fork leg can be set.

Description

[0001] Fork leg, telescopic fork and method for adjusting the length of a fork leg

[0002] The present invention relates to a fork leg for a telescopic fork, a telescopic fork and a method for adjusting the length of a fork leg.

[0003] On motor vehicles such as motorcycles, it is convenient if the riding position or ride height can be adjusted. This ensures stability for the rider, for example at traffic lights, and also maintains freedom from lean angles when driving. Vehicles with an adjustable riding position also offer the option of adapting the vehicle's riding geometry, which increases the experience of different riding modes for the rider. Typically, the riding position is achieved primarily by moving the spring base (changing the spring preload) on the spring elements. Moving the spring base changes the quasi-static force of the spring element and thus, due to the constant weight of the vehicle, the riding position. DE 10 2011 086 772 B4, for example, describes a fork leg for a motorcycle fork with an adjustment device for the spring preload.The disadvantage of this approach is that the distribution between positive and negative spring travel also changes. This means that in the low riding position the negative spring travel increases and the positive spring travel is reduced. In the high riding position the negative spring travel is reduced and the positive spring travel is increased. On the one hand, this means that when the spring base is changed, the initial spring preload at the maximum length of the spring element decreases significantly and may be lost completely. On the other hand, when the riding position is changed to adjust the vehicle's driving geometry, the spring travel distribution is changed so unfavorably that less positive spring travel is available, especially in the dynamic driving geometry setting.

[0004] It is therefore an object of the present invention to enable a length adjustment of a fork leg which should not have any influence on the fork or in particular suspension characteristics as such.

[0005] This object is achieved by a fork leg according to claim 1, by a telescopic fork according to claim 12 and by a method according to claim 13. Further advantages and features emerge from the subclaims as well as the description and the attached figures.

[0006] According to the invention, a fork leg comprises an outer tube and an inner tube which extend along a longitudinal axis, wherein the outer tube has at least one fastening section for arranging a fork bridge and wherein the outer tube comprises a first stop and a second stop, wherein the first stop is designed to limit the immersion of the inner tube into the outer tube and the second stop its emergence and wherein the outer tube comprises an adjusting element by means of which the stops can be displaced along the longitudinal axis such that a maximum length of the fork leg can be set. The fork leg is a fork leg for a so-called USD (upside down) fork. The larger outer tube is fixedly connected to the frame of the vehicle, and the front wheel is arranged on the inner tube(s).By simultaneously moving the stops, i.e. the first stop and the second stop, the division between positive and negative travel can be maintained, even though the length of the fork leg is changed. The fact that the outer tube encompasses the first stop and the second stop does not mean that the stops necessarily have to be formed directly by the outer tube. Rather, they are, so to speak, assigned to the outer tube. The position or relative location of the stops can be expediently changed, in particular readjusted, relative to the outer tube. The aforementioned principle can be expediently used for fork legs that provide a spring function, fork legs that only provide a damping function, and fork legs in which both functionalities are combined in one fork leg.

[0007] According to one embodiment, the outer tube and the inner tube are movably mounted relative to one another via a spring element, wherein the outer tube comprises a first spring seat which can be displaced along the longitudinal axis via the adjusting element, wherein a first end of the spring element is arranged on the first spring seat. The spring element is, for example, a suspension spring, in particular a spiral spring. However, the spring element can also be an air spring element. Advantageously, the spring element as such is displaced via the adjusting element, in other words, repositioned, but advantageously not compressed. By adjusting or shifting the first spring seat, the spring element can be displaced together with the first stop and the second stop relative to the outer tube without any force being exerted on the spring element as such. The inner tube is displaced and thus also the second spring seat.The ratio of positive spring travel to negative spring travel remains advantageously constant.

[0008] In order to avoid hard contact during rebound / extension, a rebound stop spring or, more generally, a damping element, for example made of a plastic such as a rubber material or Elastogran, or even a metal stop is provided on or in the area of ​​the second stop.

[0009] According to one embodiment, the second end of the spring element rests directly or indirectly on the end or front side (near or in the area of ​​a fork leg's fork stub) of the inner tube. The inner tube is displaced together with the spring element when the length of the fork leg changes. The arrangement of the spring element on the inner tube can be realized in various ways, whereby the term "direct arrangement" does not mean that the spring element rests directly on the outer wall of the inner tube. Rather, it is to be understood that the spring element rests, for example, on a spring seat or the like attached to the end of the inner tube. "End" here means the end of the inner tube that is assigned to the wheel axle. The first end of the spring element rests on the first spring seat, which in turn is operatively connected to the adjustment element.The first spring seat can also be provided via a spacer sleeve or the like, which interacts with the adjustment element. Therefore, the first spring seat does not have to be located directly on the adjustment element. The first spring seat can also be provided via a separate component, such as the aforementioned spacer sleeve.

[0010] According to one embodiment, the second stop is provided by a first additional element that extends along the longitudinal axis and is operatively connected to the adjustment element. The first additional element is thus a component that can be displaced via the adjustment element. The second stop can be displaced together with the first stop via the additional element, thereby maintaining the ratio of positive spring travel to negative spring travel.

[0011] According to one embodiment, the first additional element is a piston rod, a cartridge unit, or a damping sleeve. A piston rod is a rod-shaped element that extends along its longitudinal axis and typically has a piston or damping unit at its end, i.e., means provided for generating a damping effect. The damping effect is advantageously adjustable, in particular mechanically or electrically adjustable. Such piston or damping units operate with valves, shims, etc. Electrical adjustment is achieved, for example, by energizing a solenoid coil, by means of which valves can be opened or closed or via which a magnetorheological fluid can be influenced.For this purpose, the magnetic coil provided in the area of ​​the piston or damping unit is connected to a line for power, signal, and / or data transmission, which leads out from the fork leg. According to one embodiment, this is an electrical line. The aforementioned cartridge unit is also known by the English term "cartridge." This is a sleeve that extends along the longitudinal axis and is typically designed to interact with the aforementioned piston or damping unit. The aforementioned damping sleeve is understood to be an inner sleeve or an inner tube that is intended to interact directly with the inner tube (not with a piston rod).

[0012] According to one embodiment, the first additional element cooperates with the inner tube or a second additional element which is assigned to the inner tube, wherein the second additional element is a piston rod, a cartridge unit or a damping sleeve.

[0013] The internal structure of the fork leg can therefore be designed very freely. This does not affect the functionality of adjusting the fork leg length. The piston rod can therefore be attached to the inner or outer tube. Accordingly, the cartridge unit can be attached to either the inner or outer tube, etc. Depending on the design, spacer sleeves or similar components can be provided.

[0014] According to a preferred embodiment, a cartridge unit is assigned to the inner tube, which interacts with the first additional element designed as a piston rod. If a spring element is provided, its second end expediently rests against the cartridge unit. The cartridge unit thus forms the second spring seat. According to another embodiment, a piston rod is arranged on the inner tube, which interacts with the first additional element designed as a cartridge unit, and wherein the second end of the spring element is assigned to the inner tube. In this embodiment, the spring element is therefore positioned in the inner tube. The piston rod has a piston or damping unit at one end. The damping unit can, as already mentioned, also be designed such that it is electrically adjustable. For this purpose, the aforementioned line is expediently guided downwards from the fork leg.The embodiment described here has the advantage that the cable can be easily led downwards out of the fork leg and does not have to experience or follow the relative movement of the adjustment element.

[0015] According to one embodiment, the adjusting element comprises at least the first stop. The first stop can be a contact surface or a contact element formed on the adjusting element. The outer tube is closed, for example, by a cover or a cover element. This cover can serve as an end stop, in other words as a first stop, for the inner tube. In addition, it can accommodate the piston rod and act as the upper seat of the suspension spring. The cover can be designed as an adjusting element that is arranged so as to be displaceable relative to the outer tube or has a section that is arranged so as to be displaceable relative to the outer tube.

[0016] Since the adjusting element has to absorb large forces, it is expediently designed to be lockable to the outer tube in a suitable manner.

[0017] Preferably, an adjustment unit is provided for displacing the adjustment element. The adjustment unit can be electrical, hydraulic, pneumatic, and / or mechanical. Depending on the design of the adjustment unit, the fork leg length can be changed even while riding. Alternatively, adjustability is also possible by providing differently designed "covers" that have different installation depths or lengths. This is a very simple implementation of the described concept. The length is then adjusted using different covers, and therefore generally cannot be done without tools. Nevertheless, it enables the riding position to be adjusted without influencing the spring or damping characteristics of the fork leg. The invention also relates to a telescopic fork, in particular to an upside-down fork, comprising at least one fork leg according to the invention.Telescopic forks typically consist of two fork legs connected by at least one fork bridge. As already mentioned, the fork legs can have the same internal structure. Alternatively, there are also designs in which one fork leg performs the spring function, while the other fork leg performs the damping function. The basic principle of adjustment, however, remains the same for both fork legs. The principle of length adjustment is also applicable to Telelever® forks.

[0018] The invention also relates to a method for adjusting the length of a fork leg, comprising the steps:

[0019] - Providing a fork leg comprising an outer tube and an inner tube which are movably mounted relative to one another, wherein a first stop is provided for limiting an immersion movement of the inner tube into the outer tube and a second stop is provided for limiting its extrusion movement;

[0020] - Moving the stops along a longitudinal axis of the fork leg to change the maximum length of the fork leg.

[0021] In particular, the stops are moved simultaneously, ensuring that the ratio of positive to negative travel remains constant. At least one mounting section for a fork bridge is provided on the outer tube. It should be noted that the advantages and features mentioned in connection with the fork leg also apply analogously and accordingly to the procedure, and vice versa.

[0022] According to one embodiment, the outer tube and the inner tube are movably mounted relative to each other via a spring element. The method preferably comprises the step:

[0023] - Moving the spring element together with the stops.

[0024] Advantageously, the stops are moved together with the spring element. The spring element is not compressed or relieved during the length adjustment, but rather moved as a whole or repositioned together with the stops. This fully preserves the original spring characteristics. Only the length of the fork leg changes. Further advantages and features will become apparent from the following description of an embodiment of a fork leg according to the invention with reference to the accompanying figures.

[0025] They show:

[0026] Fig. 1: an embodiment of a fork leg according to the invention in two lengths;

[0027] Fig. 2: the fork leg known from Fig. 1 in the compressed state.

[0028] Fig. 1 shows two fork legs 1, the fork leg 1 shown in the right half of the image being longer by an adjustment path x than the one shown in the left half of the image. The fork leg 1 comprises an outer tube 10 which has two fastening sections 14 for the arrangement of fork bridges (not shown here). An inner tube 20 is movably mounted to the outer tube 10 and has a fork stub 70 at its end or front side for the arrangement of a wheel axle. A second additional element 62 in the form of a cartridge unit 22 is assigned to the inner tube 20. Such a cartridge unit 22 is also known under the term “cartridge”. The cartridge unit 22 has a second spring seat 52 for a spring element 50 at its end. A first spring seat 51 is formed in the region of a first stop 11. This stop is designed and provided to limit an immersion movement of the inner tube 20.Extending from the first stop 11 is a first additional element 60, which in this case is designed as a piston rod 24, which forms a second stop 12 at its end. This serves directly or indirectly as an end stop during the rebound of the inner tube 20. In the present case, a rebound stop spring 54 is arranged in the region of the second stop 12. The piston rod 24 has a piston or damping unit 64 at its end. The inner tube 20 is mounted in the outer tube 10 via sliding bushings 72. Reference numeral 40 denotes an adjustment element. In this case, this is designed as a type of cover. The stops 11 and 12 can be moved along the longitudinal axis L via the adjustment element 40, whereby a maximum length of the fork leg 1 can be set or changed; compare the adjustment travel x. A comparison of the left and right halves of the image clearly shows that the spring element 50 is neither compressed nor relieved.Instead, it is displaced as such. In particular, the first spring seat 51 and the inner tube 20 together with the cartridge unit 22, on which the second spring seat 52 is formed, are displaced together. The ratio of positive spring travel to negative spring travel is advantageously not affected by the change in length. In particular, the damping and spring characteristics are not affected by the change in length. In the embodiment outlined here, the adjusting element 40 is, as mentioned, designed as a type of cover. This is configured such that it can displace the stops 11 and 12, etc. accordingly. The actual implementation will typically be more complex than outlined here. The function of an adjusting unit, be it electrical, pneumatic, hydraulic and / or mechanical, is not shown here.

[0029] Fig. 2 shows the fork leg 1 known from Fig. 1 in the compressed state. It can be seen that the inner tube 20 rests against the first stop 11. The suspension spring 50 is compressed accordingly. Otherwise, the features are known from Fig. 1 and will not be repeated here.

[0030] In an alternative advantageous embodiment, the internal structure of the fork leg sketched in Figures 1 and 2 is exactly reversed. The first additional element is designed as a cartridge unit. This has the second stop at its end and simultaneously provides the first spring seat. The second spring seat is formed, for example, at the end of the inner tube (near the fork leg), from which a second additional element designed as a piston rod extends upwards to interact with the cartridge unit. The piston or damping unit formed at the end of the piston rod is thus positioned above the spring element; see also Figures 1 and 2 (which show the exactly reversed arrangement).The basic structure, according to which the outer tube comprises the first stop and the second stop, wherein the first stop is designed to limit the immersion of the inner tube into the outer tube and the second stop its extrusion, and wherein the outer tube comprises the adjustment element, via which the stops can be displaced along the longitudinal axis such that a maximum length of the fork leg can be set, is also the same in this embodiment. Only the design or arrangement of the additional elements and, in this context, the arrangement of the spring element has changed. Apart from that, there are further variants for the internal structure of the fork leg, wherein the adjustment principle for setting the fork leg length can advantageously always be designed the same. List of reference numerals.

[0031] I wishbone

[0032] 10 Outer tube

[0033] II first attack

[0034] 12 second stop

[0035] 14 Fastening section

[0036] 20 inner tube

[0037] 21 End stop

[0038] 22 Cartridge unit

[0039] 24 Piston rod

[0040] 40 Adjustment element

[0041] 50 spring element, suspension spring

[0042] 51 first spring seat

[0043] 52 second spring seat

[0044] 54 Rebound stop spring

[0045] 60 first additional element

[0046] 62 second additional element

[0047] 64 Piston / damping unit

[0048] 70 Fork Fist

[0049] 72 sliding bushing

[0050] L Longitudinal axis x Adjustment range

Claims

Claims 1. Fork leg (1), comprising an outer tube (10) and an inner tube (20) which extend along a longitudinal axis (L), wherein the outer tube (10) has at least one fastening section (14) for arranging a fork bridge, and wherein the outer tube (10) comprises a first stop (11) and a second stop (12), wherein the first stop (11) is designed to limit the immersion of the inner tube (10) into the outer tube (20) and the second stop (12) its emergence, and wherein the outer tube (20) comprises an adjusting element (40), by means of which the stops (11, 12) are displaceable along the longitudinal axis (L) such that a maximum length of the fork leg (1) can be set.

2. Fork leg (1) according to claim 1, wherein the outer tube (10) and the inner tube (20) are mounted movably relative to one another via a spring element (50), and wherein the outer tube (10) comprises a first spring seat (51) which is displaceable along the longitudinal axis (L) via the adjusting element (40), and wherein a first end of the spring element (50) is arranged on the first spring seat (51).

3. Fork leg (1) according to claim 1 or 2, wherein a second spring seat (52) is provided directly or indirectly via the inner tube (20).

4. Fork leg (1) according to one of the preceding claims, wherein the second stop (12) is provided via a first additional element (60) which extends along the longitudinal axis (L) and which is operatively connected to the adjusting element (40).

5. Fork leg (1) according to claim 4, wherein the first additional element (60) is a piston rod (24), a cartridge unit (22) or a damping sleeve.

6. Fork leg (1) according to claim 4 or 5, wherein the first additional element (60) cooperates with the inner tube (10) or a second additional element (62) which is assigned to the inner tube (10), and wherein the second additional element (62) is a piston rod (24), a cartridge unit (22) or a damping sleeve.

7. Fork leg (1) according to one of claims 4 to 6, wherein a cartridge unit (22) is arranged on the inner tube (20), which cooperates with the first additional element (60) designed as a piston rod (24), and wherein the cartridge unit (22) comprises the second spring seat (52).

8. Fork leg (1) according to one of claims 4 to 6, wherein a piston rod (24) is arranged on the inner tube (20), which cooperates with the first additional element (60) designed as a cartridge unit (22), and wherein the piston rod comprises the second spring seat (52).

9. Fork leg (1) according to one of the preceding claims, wherein the adjusting element (40) comprises at least the first stop (11).

10. Fork leg (1) according to one of the preceding claims, wherein the adjusting element (40) can be locked relative to the outer tube (10).

11. Fork leg (1), comprising an electrical, hydraulic, pneumatic and / or mechanical adjustment unit for displacing the adjustment element (40).

12. Telescopic fork comprising at least one fork leg (1) according to one of the preceding claims.

13. A method for adjusting the length of a fork leg (1), comprising the steps: Providing a fork leg (1) comprising an outer tube (10) and an inner tube (20) which are movably mounted relative to one another, wherein a first stop (11) is provided for limiting an immersion movement of the inner tube (20) into the outer tube (10) and a second stop (12) is provided for limiting its extrusion movement; Moving the stops (11, 12) along a longitudinal axis (L) of the fork leg (1) to change the maximum length of the fork leg (1).

14. Method according to claim 13, wherein the outer tube (10) and the inner tube (20) are mounted movably relative to each other via a spring element (50), comprising the step: - displacing the spring element (50) together with the stops (11,

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