Telescopic Suspension Fork Leg and Telescopic Fork Provided Therewith

Abstract

A telescopic suspension fork leg (1, 43) is provided, with an inner tube (2) and an outer tube (3) and a damping device (7) and a spring device (5), which is arranged inside a first chamber (5) formed in the inner tube (2) or outer tube (3) and is supported with respect to a second chamber (6) formed by the damping device (7), and the telescopic suspension fork leg (1, 43) is designed to receive a damping fluid, the damping device (7) comprising a piston (9) supported on a piston rod (8) and having an upper and a lower piston surface (10); 11) and the piston (9) is displaceable within a damping tube (13) arranged substantially concentrically to the inner tube (2) and the damping tube (13) is surrounded by an annular chamber (14) arranged substantially concentrically to the damping tube (13) and a gap space (15) is formed between the inner tube (2) and the outer tube (3) and a sliding bush (28) radially surrounding the inner tube (2) is provided and the telescopic suspension fork leg (1, 43) has a sealing device (24) radially surrounding the inner tube (2), which sealing device (24) has at least one sealing means (25) supported on an outer circumferential surface (27) of the inner tube (2), and a receiving chamber (37) for receiving damping fluid is provided between the sealing device (24) and the slide bush (28), wherein the telescopic suspension fork leg (1, 43) has at least one fluid passage (38) between the receiving chamber (37) and a receiving space (39) provided on the telescopic suspension fork leg.

Claims

1: A telescopic suspension fork leg (1, 43) comprising: an inner tube (2); an outer tube (3); a damping device (7); and a spring device (5), arranged inside a first chamber (5) in either the inner tube (2) or the outer tube (3), and supported in relation to a second chamber (6) formed by the damping device (7); and wherein the telescopic suspension fork leg (1, 43) receives a damping fluid; the damping device (7) comprising a piston (9) supported on a piston rod (8), the piston comprising an upper piston surface and a lower piston surface (10; 11); the piston (9) displaceable within a damping tube (13) arranged largely concentrically to the inner tube (2); the damping tube (13) is surrounded by an annular chamber (14) arranged concentrically to the damping tube (13); and a gap space (15) formed between the inner tube (2) and the outer tube (3); a slide bushing (28) radially surrounding the inner tube (2); and wherein the telescopic suspension fork leg (1, 43) further comprises: a sealing device (24) radially surrounding the inner tube (2), which sealing device has at least one sealing means (25) supported on an outer circumferential surface (27) of the inner tube (2); and a receiving chamber (37), for receiving damping fluid, between the sealing device (24) and the slide bushing (28); and wherein the telescopic suspension fork leg (1, 43) has at least one fluid passage (38) between the receiving chamber (37) and a receiving space (39) on the telescopic suspension fork leg.

2: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the receiving space (39) is defined by either the gap space (15) or one of the first chamber (5) or the second chamber (6).

3: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the at least one fluid passage (38) is formed on the slide bushing (28) or the outer tube (3).

4: The telescopic suspension fork leg (1, 43) according to claim 1, wherein a hollow cylindrical body is provided radially between the slide bushing (28) and the outer tube (3), and the cylindrical body is provided with the at least one fluid passage (38).

5: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the at least one fluid passage (38) extends into a region supporting the sealing means (25) relatively against the outer circumferential surface (27) of the inner tube (2).

6: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the at least one fluid passage (38) is formed by a groove (51) fluidically connecting the receiving chamber (37) and the receiving space (39).

7: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the at least one fluid passage (38) is arranged on an inner circumferential surface (31) of the outer tube (3), and extends between the gap space (15) and the receiving chamber (37).

8: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the at least one fluid passage (38) is arranged on an outer peripheral surface (46) of the slide bushing (28), and extends between the gap space (15) and the receiving chamber (37).

9: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the at least one fluid passage (38) is in the form of a groove (51) extending between the receiving chamber (37) and the receiving space (39), which groove extends substantially parallel, or at an angle, to a portion of a longitudinal central axis of the telescopic suspension fork leg (1, 43), and is defined on an inner peripheral surface (31) of the outer tube (3) or on an outer peripheral surface (46) of the slide bushing (28).

10: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the at least one fluid passage (38) is a groove extending between the receiving chamber (37) and the receiving space (39), which groove is formed on an inner peripheral surface (31) of the outer tube (3) or on an outer peripheral surface (27) of the sliding bush (28), and in the shape of a helix (52) extending helically around a portion of a longitudinal central axis of the telescopic suspension fork leg.

11: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the at least one fluid passage (38) has a cross-sectional area corresponding at least to an area of an annular gap area between the inner tube (2) and the slide bushing (28).

12: The telescopic suspension fork leg (1, 43) according to claim 11, wherein the cross-sectional area corresponds to a value in the range of from one to five times the area of the annular gap.

13: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the at least one fluid passage (38) comprises at least two fluid passages (38) arranged in a circumferential direction of an outer circumferential surface of the slide bushing (28) or an inner circumferential surface of the outer tube (3).

14: The telescopic suspension fork leg (1, 43) according to claim 13, wherein the fluid passages (38) are evenly distributed in a circumferential direction.

15: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the at least one fluid passage (38) defines in a cross-sectional view a shape of a segment of a circle.

16: The telescopic suspension fork leg (1, 43) according to claim 15, comprising a suspension fork (47) with two telescopic suspension fork legs (1, 43), wherein the telescopic suspension fork legs (1, 43) are arranged such that the damping device (7) is arranged below or above the first chamber (5) receiving the spring device (4).

17: A motorcycle (48) having a front wheel (19), a rear wheel (48), a rider's saddle (49), and a drive motor (50), comprising a telescopic suspension fork (47) according to claim 16.

18: A method of manufacturing a telescopic suspension fork leg (1, 43) comprising at least one fluid passage (38) on an inner peripheral surface along a longitudinal direction of an outer tube (3), comprising the steps of: providing a tubular pipe body (53) forming an outer pipe (3); inserting a mandrel tool (55) supporting the pipe body (53) on the inside and having at least one projecting outer contour (60) into the pipe body (53) to near the at least one fluid passage (38) to be formed; moving the tubular body (53) and the mandrel tool (55) relative to each other such that the at least one projecting outer contour (60) forms, by shaping without cutting, the at least one fluid passage (38) on an inner circumferential surface of the tubular pipe body (53).

19: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the at least one fluid passage (38) is formed on the slide bushing (28) and the outer tube (3).

20: The telescopic suspension fork leg (1, 43) according to claim 1, wherein the at least one fluid passage (38) is in the form of a groove (51) extending between the receiving chamber (37) and the receiving space (39), which groove extends parallel, or at an angle, to a portion of a longitudinal central axis of the telescopic suspension fork leg (1, 43), and is defined on an inner peripheral surface (31) of the outer tube (3) and on an outer peripheral surface (46) of the slide bushing (28).

21: The telescopic suspension fork leg (1, 43) according to claim 11, wherein the cross-sectional area corresponds to a value in the range of from one to three times the area of the annular gap.

Description

[0058] The invention is explained in more detail below on the basis of the drawing. This drawing shows in:

[0059] FIG. 1 a longitudinal sectional view of a telescopic suspension fork leg according to a first embodiment in accordance with the present invention;

[0060] FIG. 2 an enlarged representation of a section II according to FIG. 1;

[0061] FIG. 3 a representation of a telescopic suspension fork leg according to a second embodiment in accordance with the present invention;

[0062] FIG. 4 a sectional view of an outer tube of the telescopic suspension fork leg according to the first or second embodiment;

[0063] FIG. 5 a perspective view of a section of the outer pipe according to FIG. 4 of the drawing to explain the position of the fluid passage;

[0064] FIG. 6 a perspective view of a section of an outer pipe according to a modified embodiment of the fluid passage;

[0065] FIG. 7 a perspective view of a slide bushing with a large number of fluid passages arranged on it;

[0066] FIG. 8 a section of a telescopic suspension fork leg according to the present invention to explain pressure measuring points;

[0067] FIG. 9 a diagram of the pressure curve at the pressure measuring points, taken from a known telescopic suspension fork leg;

[0068] FIG. 10 a diagram of the pressure curve at the pressure measuring points, recorded on the telescopic suspension fork leg as invented;

[0069] FIG. 11 a perspective view of a motorcycle with one telescopic suspension fork according to the invention with two telescopic suspension fork legs; and

[0070] FIG. 12 perspective schematic representations of a tubular body for forming the outer tube and of a tool for forming the tubular body without cutting and chipless insertion of fluid passages.

[0071] FIG. 1 of the drawing shows a telescopic suspension fork leg 1 with an inner tube 2 and an outer tube 3 and a spring device 4, which is arranged in a first chamber 5 in the embodiment of the telescopic suspension fork leg 1 shown in FIG. 1 of the drawing. The spring device 4 is supported against a damping device 7 formed by a second chamber 6, and the telescopic suspension strut 1 is designed to receive a damping fluid in the form of a fork oil which is not shown in detail.

[0072] The damping device 7 generally comprises a piston rod 8, on which a piston or working piston 9 is supported, which has an upper or first piston surface 10 and a lower or second piston surface 11, and the piston 9 is displaceable within a damping tube 13 which is largely concentric with the inner tube 2.

[0073] The damping tube 13 is surrounded by an annular chamber 14 which is largely concentric with the damping tube 13 and forms the area between the outer circumferential surface of the damping tube 13 and the inner circumferential surface of the outer tube 3.

[0074] As can be seen in more detail from FIG. 2 of the drawing, a gap space 15 is provided between the inner tube 2 and the outer tube 3, in which fork oil is located during normal operation of the telescopic suspension fork leg 1, which acts as a hydraulic damping fluid.

[0075] At the lower end of the telescopic suspension fork leg 1 there is a clamping first 16 formed on which the front wheel 19 of the motorcycle 18 can be rotatably fixed via the removable axle 17 of the motorcycle 18 shown in FIG. 11 of the drawing.

[0076] The spring device 4 is supported in the area of the clamping first 16 on a cover 20 and in the area of the opposite end on a cover 21 of a sliding sleeve 22, which can be displaced along the damping tube 13 and serves to fix and axially guide the main spring 4.

[0077] Since the interior 23 of the telescopic fork leg 1 is filled with fork oil and this must be prevented from leaking out of the telescopic fork leg 1, the fork oil must be removed as shown in FIG. 2 of the drawing, a sealing device 24 is provided radially surrounding the inner tube 2, which comprises a sealing means 25 in the form of a sealing lip 26 which bears against the outer peripheral surface 27 of the inner tube 2 and is intended to retain the fork oil at the outlet during the relative movement of the inner tube 2 relative to the outer tube 3 in the direction of the double arrow P shown in FIG. 2 of the drawing.

[0078] For axial guidance and to support the inner pipe 2 on the outer pipe 3, a slide bushing 28 is provided radially to the outer pipe 2 and concentrically thereto, which can be provided on the radial inner circumferential surface with a coating in the form of, for example, a polytetrafluoroethylene coating, which on the one hand reduces the friction during the relative movement of the inner pipe 2 on the slide bushing 28 and on the other hand also has a wear-reducing effect.

[0079] The sealing device 24, which in the embodiment shown is in the form of a rotary shaft seal 29, has a supporting body 30 in the form of a cylindrical body, which is provided for support on the inner circumferential surface 31 of the outer tube 3 and on the end face of which an elongated extension arm 33 is formed, on the end face of which, distal from the end face 32, the sealing lip 26 is formed. The sealing lip 26 is pretensioned against the outer circumferential surface 36 of the inner pipe 2 by a spiral tension spring 35 acting on the outside of the end area 34.

[0080] This configuration causes the damping fluid adhering to the outer circumferential surface 36 of the inner tube 2 due to the adhesive effect to be retained by the sealing lip 26 during the rebound movement of the telescopic suspension fork leg 1 in the direction of arrow A as shown in FIG. 2, and the fork oil thus scraped off collects in a receiving chamber 37 provided between the sealing device 24 and the slide bushing 28 or more generally in the area of the sealing device 24.

[0081] As a result of the further rebound movement of the telescopic suspension fork leg 1 with the movement of the inner tube 2 in the direction of arrow A according to FIG. 2, more oil accumulates in the receiving chamber 37 and this leads to a build-up of back pressure in the receiving chamber 37.

[0082] In the case of a known telescopic suspension fork leg, this accumulation of fork oil in the receiving chamber leads to pressure conditions which can be seen in more detail in FIG. 9, as can be determined using a measuring set-up explained below in FIG. 8 of the drawing.

[0083] The measuring set-up according to FIG. 8 shows a section according to area VIII of FIG. 2 of the drawing. The pressure diagram according to FIG. 10 of the drawing was also determined with the measuring set-up shown in FIG. 8, which shows the pressure conditions with a telescopic suspension strut 1 according to the invention, while FIG. 9, used for comparison, shows the pressure conditions with the known telescopic suspension strut.

[0084] FIG. 8 shows the inner tube 2 and the outer tube 3 as well as the sealing device 24 with the receiving chamber 37 and the gap space 15 between the inner tube 2 and the outer tube 3. FIG. 8 also shows a bore 12 provided on the inner tube 2, through which fork oil, which flows via the bypass channel 38 into the gap space 15, can easily flow into the interior of the telescopic suspension fork leg 1. It is also possible to provide several holes 12 on the circumference of the inner tube 2, so that the flow resistance for the fork oil flowing into the gap space 15 is further reduced.

[0085] The one in FIG. 8 is now characterized by the fact that the telescopic suspension strut 1 has a fluid passage 38 or fluid channel or bypass channel between the receiving chamber 37 and the gap space 15, which ensures that the telescopic suspension strut 1 is not damaged, in that the fork oil accumulating in the receiving chamber 37 can flow via the fluid passage 38 into the receiving chamber 39, which is designed as a gap chamber 15 in the illustrated design, and the formation of a dynamic pressure in the receiving chamber 37, which still occurs in the configuration of the known telescopic suspension fork leg, can thus be avoided.

[0086] FIG. 9 of the drawing shows the pressure conditions in the receiving chamber and the gap space with a known telescopic suspension strut, which differs from the configuration according to FIG. 8 of the drawing in that the known telescopic suspension strut does not have the fluid passage or fluid channel or bypass channel 38.

[0087] To determine the pressure conditions shown in the diagrams in FIG. 9 and FIG. 10 of the drawing, the pressure in chamber A and chamber B is measured, which is the result of a dynamic spring movement of the telescopic suspension fork leg.

[0088] FIG. 9 shows the pressure conditions which result from the measuring set-up shown on the known telescopic suspension fork leg, while FIG. 10 shows the pressure conditions which result from the measuring set-up shown on the telescopic suspension fork leg 1, which is in accordance with the invention.

[0089] To determine the pressure conditions, both the known and the invented telescopic suspension fork leg were subjected to a test drive, which is characterized by a sinusoidal spring movement, which is shown in the diagram according to FIG. 9 and in the diagram according to FIG. 10, each with a sinusoidal oscillation 40, which led to the pressure conditions also shown.

[0090] Curve 41 according to FIG. 9 shows the pressure build-up at the measuring point of chamber B according to FIG. 8, while curve 42 shows the pressure build-up at the measuring point of chamber A according to FIG. 8.

[0091] As can be seen from FIG. 9 of the drawing, the pressure build-up in chamber B follows the internal pressure in the gap 15 corresponding to the compression position or the interior of the telescopic suspension fork leg, since the air volume enclosed in the telescopic suspension fork leg is compressed by the compression movement and thus the internal pressure in the interior 23 of the telescopic suspension fork leg changes periodically with the periodically oscillating compression position.

[0092] Curve 42, which shows the pressure curve in the measuring point of chamber A according to FIG. 8, i.e. the internal pressure determined in chamber A, the internal pressure initially drops significantly with the increasing compression position of the known telescopic suspension fork leg, it even drops below the ambient pressure of the pressure curve shown in FIG. 9 and FIG. 10, which means that at the measuring point of chamber A a negative pressure is established, which leads to the fact that air from the environment can flow into the interior 23 of the known telescopic suspension fork leg, which is then enclosed in the interior and leads to the above described problem of inflating the known telescopic suspension fork leg.

[0093] After the maximum compression position marked with the turning point X is reached and the telescopic suspension fork leg is subjected to a rebound movement, fork oil is entrained into chamber A by the inner tube, which is wetted with fork oil on the outer circumference, and the problem of the formation of dynamic pressure described above occurs there, whereby the ram pressure is applied to the boom, with the result that the sealing lip of the known telescopic suspension fork leg is pressed with high pretension against the outer circumferential surface of the inner tube of the known telescopic suspension fork leg, thereby significantly increasing the friction at the point of contact between the sealing lip and the outer tube of the known telescopic suspension fork leg.

[0094] The pressure curve 42 shows that as the internal pressure 41 decreases, the pressure in chamber A increases abruptly and therefore the sealing device with the sealing lip resting on the outer circumference of the inner tube must be able to cope with a much larger pressure range than is given by the internal pressure prevailing in the telescopic suspension fork leg. Since even a negative pressure is created in chamber A during the compression movement of the known telescopic suspension fork leg, this leads to the sealing lip losing its contact with the outer circumference of the inner tube of the known telescopic suspension fork leg and thus to leaks. This can only be compensated for by the fact that the spiral tension spring applies a high preload to the sealing lip of the known telescopic suspension fork leg against the outer circumferential surface of the inner tube, which results in a high surface pressure in the area of the sealing lip and the outer tube, which in turn leads to a high frictional torque at the contact point and thus to poor response behavior of the known telescopic suspension fork leg.

[0095] Since the spring movement is constantly repeated during the driving operation of a vehicle equipped with the known telescopic suspension strut, the effect of inflating the interior of the known telescopic suspension strut causes the internal pressure to increase significantly and must be released by actuating a valve provided on the known telescopic suspension strut. The response of the known telescopic shock absorber is therefore not constant, but is subject to large fluctuations which can be detected by the driver of the vehicle equipped with it while driving.

[0096] If, for example, a vehicle equipped with the known telescopic suspension strut passes over a washboard-like road profile while driving, the large number of spring movements occurring in a short time leads to a drastic change in the response behaviour of the known telescopic suspension strut within a short time, which is perceived by the driver of the vehicle as a deterioration of the response behaviour, since this deterioration also occurs in particular at different time intervals, depending on how many spring movements the known telescopic suspension strut experiences while driving.

[0097] FIG. 10 of the drawing shows, in direct comparison to FIG. 9 of the drawing, the significant improvement achieved with the telescopic suspension strut 1, which is in accordance with the invention.

[0098] Curve 40 again shows the sinusoidal spring deflection position and the two curves 41 and 42 in FIG. 9, which still deviate considerably from each other in their course, coincide in FIG. 10. The pressure curve in chamber A of the telescopic suspension fork leg 1 now follows the pressure curve in chamber B of the telescopic suspension fork leg 1, since the rebound movement in the receiving chamber 37 (chamber A) allows fork oil entrained in the rebound movement to flow via the bypass channel 38 into the receiving chamber 15, which is formed, for example, by the gap 15 (chamber B) between the outer tube 3 and the inner tube 2.

[0099] The curves in FIG. 10 show that with a compression movement of the telescopic suspension fork leg 1, i.e. with increasing compression position, the pressure in chamber A (receiving chamber 37) increases in the same way, i.e. with corresponding speed and amplitude, as the pressure in chamber B (gap chamber 15) and with a rebound movement decreases again in the same way as the pressure in chamber B, i.e. the pressures in chamber A and chamber B largely correspond or are largely the same. Thus, it can also be easily determined whether a telescopic suspension fork leg to be examined corresponds to a known telescopic suspension fork leg or corresponds to the telescopic suspension fork leg according to the invention.

[0100] The fact that the telescopic shock absorber, as defined in the invention, no longer suffers from the formation of a vacuum in the receptacle chamber corresponding to chamber A also makes it possible to reduce the preload to be applied by the spiral tension spring 35 without adversely affecting the tightness, thus eliminating the phenomenon of inflation of the telescopic shock absorber described above, the telescopic suspension fork leg according to the invention and a telescopic suspension fork formed therewith are characterised by a constant response behaviour even in dynamic operation, also short spring movements of the telescopic suspension fork according to the invention with the telescopic suspension fork legs according to the invention caused by a road surface formed like a washboard ensure that the response behaviour of the telescopic suspension fork when driving over the last excitation does not differ from the response behaviour when driving over the first excitation.

[0101] A user or driver of a vehicle which has a telescopic suspension fork with the telescopic suspension strut according to the invention will not experience any change in the response behaviour of the telescopic suspension fork even during a racing event with the vehicle and therefore does not have to adjust to the fact that the telescopic suspension fork shows a different response behaviour at the beginning of a race, for example, than is the case in the final phase of the race. This also makes it possible, for example, for the speed of the vehicle to increase when driving through curves with uneven road surfaces, as the telescopic suspension fork always shows a constant response behaviour, i.e. spring and damping behaviour, and does not show a hardening response behaviour even with increasing driving time.

[0102] FIG. 3 of the drawing shows a longitudinal sectional view of a telescopic suspension fork leg 43 according to a modified version according to the present invention. As can be seen without further ado, the telescopic suspension strut shown in FIG. 3 differs from the telescopic suspension strut 1 according to FIG. 1 in that the telescopic suspension strut 43 has a spring device 4 which is arranged at the opposite end region of the telescopic suspension strut 43 instead of in the region adjacent to the clamping first 16, i.e. in the vertical axis direction H, which can also be seen in FIG. 11 of the drawing, is arranged at the top instead of the arrangement at the bottom according to FIG. 1 of the drawing.

[0103] The telescopic suspension strut 43 shown in FIG. 2 of the drawing again shows a section II, which corresponds to the configuration according to the illustration in FIG. 2 of the drawing, since the second version of the telescopic suspension strut shown in FIG. 3 of the drawing also has a fluid passage 38 between the receiving chamber 37 and the receiving space 39 provided on the telescopic suspension strut 43, which again corresponds to the gap space 15 between the inner tube 2 and outer tube 3. The second version of the telescopic suspension strut 43 shown in FIG. 3 of the drawing therefore has the same advantages as those already explained above with reference to the telescopic suspension strut 1 shown in FIG. 1.

[0104] FIG. 4 of the drawing shows a sectional view of the outer tube 3 according to section IV-IV as shown in FIG. 2 of the drawing, whereby the slide bushing 28 shown in FIG. 2 of the drawing and the complete inner construction of the telescopic suspension fork leg 1 have been omitted for the sake of simplicity.

[0105] The outer pipe 3 has an inner circumferential surface 31 on which the slide bushing 28, which can be a hollow cylindrical body, as shown in FIG. 2 of the drawing, can be arranged. The outer pipe 3 has three equidistantly distributed fluid passages 38, each of which is angularly spaced at 120 degrees to each other and is circular-segment-shaped and has a total cross-sectional area which, in the design shown, is three times the cross-sectional area of the annular gap between the slide bushing and the outer circumferential surface of the inner pipe 2. This design ensures that a bypass channel or flow channel is made available to the fork oil accumulating in the receiving chamber 37 so that it can flow into the gap space 15 between outer tube 3 and inner tube 2 without any great flow resistance and thus the pressure distribution already described above and shown in FIG. 10 of the drawing is achieved. In the variant shown, the fluid outlets designed in the form of a groove 51, which is circular segment-shaped. This shape has the advantage of a lower notch effect and the associated lower influence on the strength of the outer pipe 3.

[0106] FIG. 5 of the drawing shows a perspective view of the outer tube 3 of the telescopic suspension fork leg 1, 43 with a fluid channel 38 shown on a contact surface 45 for receiving the slide bushing 28. Three fluid channels 38 are also provided in this version of the outer tube 3, of which only one fluid channel 38 is visible due to the selected representation.

[0107] FIG. 6 of the drawing shows a modified version of an outer tube 3, in which the fluid channel 38, through which the fork oil or damping fluid collected in the receiving chamber 37 can flow into the gap space 15 between outer tube 3 and inner tube 2, is of spiral or helical design and extends along a partial longitudinal extension of the outer tube 3. This fluid channel 38, which is also spiral or spiral-shaped in the form of a helix or spiral 52, ensures that no dynamic pressure is formed in the receiving chamber 37 and that the pressure conditions shown in reference to FIG. 10 of the drawing are achieved.

[0108] FIG. 7 of the drawing shows a perspective view of a slide bushing 28 with fluid channels 38 formed on its outer circumferential surface 46 and arranged at an angle to the longitudinal axis of the slide bushing 28, which is formed by a hollow cylindrical body.

[0109] Via these fluid channels 38 the fork oil accumulating in the receiving chamber 37 can flow off in the direction of the gap 15 between the inner tube 2 and the outer tube 3, so that the pressure conditions shown in FIG. 10 of the drawing and already explained above are again established.

[0110] The above mentioned motorcycle 18 is shown in FIG. 11 of the drawing. The motorcycle 18 has a telescopic suspension fork 47 which has two telescopic suspension fork legs 1 as shown in FIG. 1 of the drawing. The motorcycle 18 is an off-road sports motorcycle which can be used for example in motocross competitions and therefore has a telescopic fork which is subject to very high dynamic suspension movements. The motorcycle 18 has a front wheel 19 and a rear wheel 48 as well as a driver's saddle 49 and a drive engine 50, which in the version of the motorcycle 18 shown here is a four-stroke engine.

[0111] It is also an advantage on such an off-road sports motorcycle if the response of the telescopic suspension fork 47 does not change during a competition ride, as this also ensures that the rider of the motorcycle does not have to change his riding style.

[0112] FIG. 12 of the drawing shows three schematic perspective representations to explain the process of manufacturing the outer tube 3 of the telescopic suspension fork leg 1, 43 according to the invention by means of a non-cutting shaping process or non-cutting forming with simultaneous formation of the fluid passages or bypass channels or fluid channels already explained above.

[0113] As can be easily seen from the drawing and in particular from the upper illustration in FIG. 12, a tube body 53 and a tool 54 in the form of an inner mandrel 55 are first provided, which has stepped forming surfaces 56 on its outer circumference to form the diameter steps 57 of the outer tube 3 to be produced.

[0114] As can also be seen from FIG. 12, the inner mandrel 55 has 59 projections 60 on its central forming surface 59 arranged in the longitudinal direction and equally distributed at an angle in the circumferential direction, of which only one projection 60 is visible in FIG. 12 due to the perspective selected, with which the three fluid passages 38 shown in FIG. 4 of the drawing can be formed without cutting.

[0115] To do this, first prepare the tube body 53 to be formed into the outer tube 3 and the tool 54, as shown in the upper illustration in FIG. 12, and then insert the tool 54 into the front opening 61 of the tube body 53, as shown in the middle illustration in FIG. 12. In this process, both the diameter graduations 57 are formed on the tube body 53 and the groove-shaped fluid passages 38 are produced on the middle diameter graduation 62 without cutting, of which only one fluid passage 38 can be seen in the perspective selected in the lower illustration of FIG. 12.

[0116] The manufacturing process according to the invention is characterized by the fact that the outer tube 3 can be formed without cutting and at the same time the fluid passages 38 can be formed.

[0117] The telescopic suspension fork leg according to the invention and the telescopic suspension fork equipped with it are characterized by the advantages that, on the one hand, the problem of inflating the telescopic suspension fork or the telescopic suspension fork leg is eliminated and the response behavior of the telescopic suspension fork does not change even during highly dynamic movements while the vehicle equipped with it is moving. In addition, it has been shown that the continuous increase in friction of the telescopic suspension fork according to the invention is significantly lower during long operation compared to the known telescopic suspension fork, since there is a significantly improved oil circulation in the area of the sealing lip and the slide bushing and therefore any dirt particles do not remain in these contact zones between the sealing lip and the inner tube and the slide bushing and the inner tube, but are continuously flushed out.

[0118] The continuous circulation of the fork oil also ensures that the shear stresses occurring in the contact area and stressing the fork oil are reduced and therefore the aging process of the fork oil used is also slowed down, which in turn can be used to increase the intervals at which the fork oil is changed. The reduced shear stress also ensures that the fluid friction occurring in the shear gap is reduced and thus the frictional torque behaviour of the telescopic suspension fork leg according to the invention and the telescopic suspension fork equipped with it is reduced in comparison with the known telescopic suspension fork leg and the telescopic suspension fork equipped with it, which in turn ensures that the telescopic suspension fork according to the invention responds more sensitively to road unevenness than the known telescopic suspension fork.

[0119] With regard to features of the invention not further explained in detail above, explicit reference is made to the claims and the drawing.

LIST OF REFERENCE SIGNS

[0120] 1. telescopic suspension fork leg [0121] 2. inner pipe [0122] 3. outer tube [0123] 4. spring device [0124] 5. first chamber [0125] 6. second chamber [0126] 7. damping device [0127] 8. piston rod [0128] 9. piston [0129] 10. upper piston surface [0130] 11. lower piston surface [0131] 12. bore [0132] 13. damping tube [0133] 14. annular chamber [0134] 15. splitting room [0135] 16. clamping first [0136] 17. thru axle [0137] 18. motorcycle [0138] 19. front wheel [0139] 20. cover [0140] 21. cover [0141] 22. sliding sleeve [0142] 23. interior [0143] 24. sealing device [0144] 25. sealant [0145] 26. sealing lip [0146] 27. outer circumferential surface [0147] 28. slide bushing [0148] 29. radial shaft seal [0149] 30. body [0150] 31. inner circumferential surface [0151] 32. end range [0152] 33. jib [0153] 34. end range [0154] 35. spiral tension spring [0155] 36. outer circumferential surface [0156] 37. receiving chamber [0157] 38. fluid passage [0158] 39. recording room [0159] 40. sine wave [0160] 41. curve [0161] 42. curve [0162] 43. Telescopic suspension fork leg [0163] 44. annular gap [0164] 45. contact surface [0165] 46. outer circumferential surface [0166] 47. Telescopic suspension fork [0167] 48. rear wheel [0168] 49. driver saddle [0169] 50. drive motor [0170] 51. groove [0171] 52. helix, spiral [0172] 53. tube body [0173] 54. tool [0174] 55. internal mandrel [0175] 56. forming area [0176] 57. diameter gradations [0177] 58. diameter gradation [0178] 59. forming area [0179] 60. lead [0180] 61. opening [0181] 62. average diameter gradation [0182] P double arrow A extension movement H high axis direction