Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
  • B62K25/00—Axle suspensions
  • B62K25/04—Axle suspensions for mounting axles resiliently on cycle frame or fork
  • B62K25/06—Axle suspensions for mounting axles resiliently on cycle frame or fork with telescopic fork, e.g. including auxiliary rocking arms
  • B62K25/08—Axle suspensions for mounting axles resiliently on cycle frame or fork with telescopic fork, e.g. including auxiliary rocking arms for front wheel
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
  • F16F9/32—Details
  • F16F9/36—Special sealings, including sealings or guides for piston-rods
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
  • F16F9/32—Details
  • F16F9/36—Special sealings, including sealings or guides for piston-rods
  • F16F9/365—Special sealings, including sealings or guides for piston-rods the sealing arrangement having a pressurised chamber separated from the damping medium

Definitions

• the invention is applied to a front fork in which a pressurized damping system is disposed in the outer legs of the front fork.
• the damping system is filled with a fluid damping medium in the form of, for example, oil with known additives, and in order to maintain the pressurization it is delimited from the environment by one or more seals.
• a front fork for a two-wheeled vehicle is made up of an outer leg and an inner leg in which there is disposed a damping cylinder filled with damping medium.
• the damping cylinder is divided into two damping chambers by a piston fixed to a piston rod joined together with the outer leg.
• the piston rod extends through one end off the damping cylinder and the damping medium in the damping cylinder is delimited from the inner volume of the front fork by a seal placed in a sealing head.
• the interior of the front fork is also partially filled with oil.
• a reservoir is pressurized by an external pressurizing member coupled with the interior of the damping cylinder, so that the damping medium is always subjected to a certain pressure.
• the reservoir can be coupled with one or both damping chambers. If both damping chambers are coupled with the reservoir, the damping during a return and compression stroke respectively can be adjusted independently of each other via two separate adjustable valves.
• the seal disposed in the sealing head is subjected to high pressures, whilst, at the same time, it has to effect a seal between a pressurized oil and a non-pressurized oil. It has proved to be a problem to effect a seal between two oil-filled spaces under the conditions prevailing in a front fork. Oil either leaks out from the pressurized space or is sucked into it, in which case the pressure ratios in the front fork are no longer optimal.
• the present invention aims to solve the problem of oil leaking out of or being sucked into a damping cylinder in a pressurized oil-filled front fork.
• the invention also aims to solve this problem in a simple and economical manner by using a new type of seal design and by utilizing components already present in the fork leg to prevent the leakage.
• the invention relates to a front fork having an inner first volume which is at least partially filled by a first fluid medium in the form of an oil.
• the outer structure of the front fork is made up of an outer leg and an inner leg, which move telescopically relative to each other when subjected to an external force. The movement is controlled by a main spring and is dampened by a damping device.
• the damping device is in the form of a damping cylinder, sealed off from the inner first volume of the front fork, having a second volume filled with a second fluid medium, also in the form of an oil, which is pressurized at a basic pressure higher than the atmospheric pressure.
• the damping cylinder is divided into two damping chambers by a piston fixed to a piston rod.
• the piston rod extends through a first sealing head fixed at one end of the damping cylinder. Outside the damping cylinder, directly adjacent to the first sealing head, there is disposed a third volume, delimited by a cylindrical body filled with a gas, preferably air, and disposed around the piston rod.
• the first sealing head is fixed to a first end of the cylindrical body, preferably to the internal face of the cylindrical body.
• the gas-filled third volume prevents direct contact between the first and the second fluid medium.
• the demarcations between the gas-filled third volume and the inner oil-filled first volume of the front fork, and between the gas- filled third volume and the oil-filled second volume of the damping cylinder, comprise at least one seal each, suitable for sealing between fluid medium and gas.
• the seal is preferably an X-ring or a lip seal with necessary backup rings.
• At least one groove for the boundary seal is machined directly in the cylindrical body which encloses the gas-filled volume.
• At least one groove for the seal is machined in a second sealing head disposed on a second end of the cylindrical body.
• first sealing head or if a second sealing head is also used, both these sealing heads, is/are connected to the internal face of the cylindrical body.
• the internal connection between sealing head(s) and the cylindrical body can be provided by means of a joint in which at least one ring made of an elastic material is disposed in a first groove in the respective sealing head and cooperates with a second groove disposed in the cylindrical body.
• the internal connection can also be provided by means of a threaded joint or by means of a press fit between the parts.
• the outer face of the cylindrical body is also arranged to control the movements of the main spring and centre its position in the interior of the front fork.
• the cylindrical body is made of a polymer, preferably polyamide with various additives.
• the cylindrical body is also made of an existing spring support material.
• FIG. 1 shows a pressurized front fork according to a first embodiment of the invention
• Fig. 2 shows an enlarged view of a first sealing head in the front fork
• Fig. 3 shows an enlarged view of a first embodiment of a second sealing head in the front fork
• Fig. 4 shows an enlarged view of a second embodiment of a second sealing head in the front fork.
• FIG. 1 shows a front fork 1 according to a first embodiment of the invention.
• the front fork 1 has an inner first volume 1a, which is filled to between 75% and 90% with a first fluid medium 01 in the form of an oil with necessary additives.
• the remaining part of the inner first volume 1a is filled with a first gas G1 , preferably air.
• the outer structure of the front fork is made up of an outer leg 2 and an inner leg 3, which move telescopically relative to each other when subjected to an external force.
• the external force is absorbed by a main spring 4 disposed in the inner first volume 1a and is dampened by a damping device 5.
• the damping device 5 is disposed in the inner first volume 1a, but is delimited from the first fluid medium O1 therein.
• the inner first volume 1a is delimited at its upper end by a fork head 7 secured in the outer leg 2.
• the first end 8a of a piston rod 8 is secured in the fork head 7.
• a first piston 9 which divides a damping cylinder 6 in the damping device into two damping chambers C, R.
• the piston rod 8 extends also through a first sealing head 10 fixed at the first end 6a of the damping cylinder.
• the damping cylinder 6 is filled with a second fluid medium 02, this too in the form of an oil.
• the oil 02 in the damping cylinder 6 is pressurized on both sides of the first piston 9 in a manner already known through the Applicant's so-called TTX technology.
• the TTX principle in this front fork can briefly be described as follows.
• the first flow duct 14 extends from the common second volume 13, between the damping cylinder 6 and a further pipe 16 enclosed around this, and is terminated in the return chamber R.
• valves 17, 18 are arranged to adjust the flow in the flow ducts 14, 15, i.e. with these valves the damping characteristics of the front fork can be determined.
• the pressurizing reservoir 12 is fixed to a bottom piece 19 intended to be fixed to a wheel (not shown).
• the bottom piece 19 is fixed to the lower part 3a of the inner pipe 3 and incorporates within it the common second volume 13, the adjustable valves 17, 18 and the sub-ducts 14a, 15a linking the flow ducts 14, 15. Since the two damping ducts C, R are coupled with the pressurized common second volume 13, the pressure is never less than zero in any of the chambers C, R.
• the invention can also be applied to a front fork which is based on the older de Carbon principle, as the damping system is only pressurized by the pressurizing reservoir on one side of the piston.
• FIG. 2 an enlarged view of the sealing head 10 is shown.
• the sealing head 10 delimits the inner volume 5' of the damping device 5, filled with damping medium O2, with one or more seals 10a, 10b arranged to seal off both against the piston rod 8 and against the inner leg 3.
• This body 20 encloses a third volume 21 filled with a gas G3, preferably air.
• the body 20 is fixed at a first end 20a to the sealing head 10, and between these parts, too, one or more seals 10c are provided.
• the seals 10a, 10b, 10c are suitable for effecting a seal between the fluid medium O1 , O2 and the gas G3, preferably an O-ring, X-ring or a lip seal with necessary backup rings being able to be used.
• a bushing 23 for reducing the friction when the parts 2, 3 of the front fork move in relation to each other.
• the body 20 is fixed to the sealing head 10 by the fact that the seals 10c rest in grooves 22a, 22b milled in both the sealing head 10 and the body 20.
• the seals 10c are pressed into the grooves and thereby hold the body in place.
• this assembly method can be adapted so as to optimize the sealing of the inner volume 21 of the body.
• Other securing methods too, may be used, for example the parts 10, 20 can be fixed together with a threaded joint or with a simple press fit.
• a second sealing head 24 is pressed in inside the body 20 at its second end 20b.
• at least one seal 25 is arranged to effect a seal between the inner gas-filled third volume 21 of the body 20 and the inner oil-filled first volume 1a of the front fork.
• a bushing 26 is also provided on the inner side of the sealing head 24 to reduce the sliding friction against the piston rod 8.
• the second sealing head 24 is securely held and is sealed against the body 20 in the same way as the body 20 is fixed to the first sealing head 10, i.e. with elastic rings, for example seals 27 in grooves 22a', 22b'.
• other securing methods such as, for example, a threaded joint, may also be used.
• At least one groove for the seal(s) 25 is machined directly in the body 20. If the body 20 is made of a low- friction material such as a polymer, preferably polyamide with various additives, the bushing between the piston rod 8 and the body 20 can be omitted.
• a low- friction material such as a polymer, preferably polyamide with various additives
• the body 20 can also have other fields of application, given that it controls the movements and centred position of the main spring 4 in the interior 1a of the front fork.
• the outer face 20c of the body 20 has a small diametrical clearance s, preferably of between 0.2 and 2 mm, against the inner face of the main spring 4. As a result of this clearance, the spring 4 does not lock against the body, but instead slides against the outer face 20c.
• the cylindrical body 20 according to the invention is made of a polymer spring support material.
• the spring support is modified only by the fact that, at its two ends, the sealing head(s) 10, 24 are secured and/or a groove is milled for a seal 23. This simple modification of the pre-existing spring support means that the inventive problem of sealing off a pressurized damping system is solved in an economical and resource-saving manner.
• the assembly of the front fork can be facilitated and/or the production cost can be reduced by the sealing head 10 being composed of a plurality of parts fitted together by means of threaded joints or a press fit.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Fluid-Damping Devices (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=39608884

Family Applications (1)

Country Status (2)

Cited By (9)

Citations (4)

• 2007
  • 2007-01-10 SE SE0700033A patent/SE531829C2/sv not_active IP Right Cessation
  • 2007-12-13 WO PCT/SE2007/050990 patent/WO2008085097A1/en active Application Filing

Patent Citations (4)

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