EP2451700A1 - Steering stabilizer for bikes - Google Patents

Abstract

A steering stabiliser, in particular for bicycles, comprising a hollow main body (10) fitted with attachment devices (12) to the bicycle frame (80) and defining within it a main cavity (14) in which at least one separation wall (16) extends which divides said main cavity (14) into at least two containment chambers (18, 20) of a stabilising fluid. The two chambers (18, 20) are in fluidic communication with each other at least through a calibrated cross-section duct (22). The separation wall (16) has at least one mobile portion (16) able to cause a variation of equal size and opposite direction in the volume of said two chambers (18, 20) and which can be operatively connected to the steering axis (X) of the bicycle, so that a rotation of said axis (X) causes a shift of said mobile portion (16') and therefore transit of the stabilising fluid from one containment chamber to the other.

Description

STEERING STABILIZER FOR BIKES

[001] The present invention relates to a steering stabiliser, in particular for bicycles.

[002] As is known, in the motorbike sector steering stabilisers or shock absorbers able to prevent sudden and undesirable rotation of the front steering wheel which may cause the motorcyclist to fall, are already used. Such devices are made using linear pistons, generally rather heavy and cumbersome, with a steering angle of about +40°, -40°.

[003] In the bicycle sector too however it would be desirable and opportune to be able to act on the steering mechanism so as to absorb all the oscillations and sudden changes of direction conveyed to the steering column, for example by the terrain or sudden obstacles, and thus prevent sudden, involuntary swerving with consequent possible falling of the cyclist. Such action on the steering mechanism would also offer the cyclist a more comfortable and less stressful ride in that it would not require continuous control of the steering mechanism, especially in the off-road sector.

[004] The devices used on motorcycles however, given their characteristics, mentioned above, are not applicable to bicycles, since these must be as light as possible, as slender as possible and able to steer by about 90°.

[005] The purpose of the present invention is to satisfy the above requirements in the bicycle sector, both professional and amateur, for road rather than off-road use, on any road or circuit, absorbing shocks and stress transmitted to the steering mechanism by holes, stones or other unforeseen obstacles, as well as the oscillations conveyed to the frame during particularly intense pedalling .

[006] Such purpose is achieved by a steering stabiliser according to claim 1. The dependent claims describe preferred or advantageous embodiments of the stabiliser.

[007] The characteristics and advantages of the device according to the invention will, however, be more evident from the description below of its preferred embodiments made by way of a non-limiting example with reference to the attached figures, wherein:

Figure 1 is a perspective view of the steering stabiliser according to the invention, according to one embodiment;

- Figure 2 is a schematic view, in partial cross-section, of the device in one embodiment;

- Figure 3 is a transversal cross-section view of the main body and command shaft of the device, in one embodiment; - Figure 4 is a transversal cross-section view of the main body, in one embodiment variation;

Figure 5 shows a perspective view, of part of the steering group of a bicycle which the stabiliser device has been mounted on, in one assembly mode;

- Figure 5a shows the same part of the steering group with the stabiliser device, but seen from the side; and

Figure 6 shows, seen from the side, part of the steering group of a bicycle which the stabiliser device has been mounted on, in an alternative assembly mode.

[008] In said figures, reference numeral 1 globally denotes in its entirety, a steering stabiliser applicable, in particular, to a bicycle.

[009] The device according to the invention is applicable in particular to a steering group of a bicycle, comprising a handlebar and a fork 50, which may be fixed or cushioned. The handlebars are connected, for example, by means of a steering tube 60, to the stem 52 of the fork. Said stem 52 is housed in a head tube 70, which is part of the bicycle frame 80, and are able to rotate around their axis, coinciding with the axis of the tube, for example thanks to bearings. The stem 52 of the fork thereby identifies a steering axis X. In one embodiment, the stem 52 of the fork extends from a support plate 54 of the arms 56 of the fork 50, for example cushioned arms .

[0010] According to a general embodiment, the device 1 comprises a main hollow body 10 fitted with attachment devices 12 to the bicycle frame 80. The main body 10 is thereby joined to the bicycle frame 80. Said body 10 defines within it a main cavity 14 in which at least one separation wall 16 extends, dividing said main cavity 14 into at least two chambers 18, 20 containing a stabilising fluid, such as oil.

[0011] The two chambers 18, 20 are in fluidic communication with each other through at least one duct 22 with a calibrated through section.

[0012] The separation wall 16 has at least one mobile portion 16' able to cause a variation of equal size and opposite direction in the volume of the two containment chambers 18, 20. Said mobile portion 16' is operatively connectable to the steering axis X of the bicycle, in such a way that a rotation of said axis corresponds to a displacement of said mobile portion 16' and therefore the passage of the stabilising fluid from one containment chamber to the other.

[0013] In other words, the volume of the main cavity 14 being constant and essentially the. sum of the two volumes of the two containment chambers, the reduction of volume in one chamber corresponds with an increase in volume in the other chamber. Thanks to the calibrated cross-section 22 of the duct placing the two chambers in fluidic communication, the reduction of volume in one chamber and the increase of volume in the other causes transit of the stabilising fluid from the first to the second.

[0014] The cross-section of the duct 22 between the two chambers determines the speed of the flow of fluid from one chamber to the other or, in other words, the resistance which the fluid poses to the movement of the mobile portion 16' of the separation wall 16.

[0015] A calibrated cross-section duct is taken to mean that the cross-section of transit of the fluid from one chamber to the other is chosen so as to provide the right compromise between fluid steering and the resistance of the steering mechanism to sudden and unexpected stress.

[0016] In one embodiment, the main cavity 14 extends essentially around a main axis of symmetry Y. Advantageously, the main body 10 is suitable for mounting on the steering group of the bicycle so that said main cavity 14 is coaxial with the steering axis X. This way, as will be explained further below, the steering group acts directly on the stabiliser device, without the need for transmission devices or other intermediate elements which could create play in the fit, highly prejudicial and counterproductive to stability. [0017] Preferably, the main cavity 14 is an essentially cylindrical shape and the separation wall 16 is coplanar to the longitudinal axis Y of said cavity. In other words, the separation wall 16 divides the volume of the main cavity 14 into two chambers which, seen in a transversal cross-section, are the shape of circle sectors.

[0018] In one embodiment, the separation wall 16 comprises a fixed radial portion 16" and a mobile radial portion 16' able to rotate around the longitudinal axis Y of the main cavity.

[0019] More specifically, the mobile radial portion 16' is attached to a command shaft 26 which extends axially in the main cavity 14 of the hollow body 10 and which protrudes from said body to connect to the steering group of the bicycle.

[0020] A radial portion, fixed or mobile, means that it is directed along the radius of the main cavity 14, even if the transversal or radial dimension of said portions is less than the length of the radius of the cavity as a result of the presence of the command shaft 26.

[0021] In particular, the mobile radial portion 16' is attached the command shaft 26 along a single inner vertical side. The other three sides of the radial portion 16' are placed in contact with the upper, lateral and lower sides of the main cavity 14 and then fitted with a perimetral sealing element 17 able to form a dynamic seal with said surfaces.

[0022] In one embodiment, the fixed radial portion 16" is made in one piece with the main body 10, being configured as a radial projection which extends from the inner surface of the main cavity as far as to come into contact with the command shaft 26. Advantageously, the contact surface with said command shaft 26 is a concave surface complementary to the surface of the shaft. In said concave contact surface, advantageously, at least one, preferably two, longitudinal seats 19 are made, in which a sealing element extending the whole height of the fixed radial wall is inserted. The use of two sealing elements distanced from each other offers a double point of contact between the fixed radial wall and the command shaft and therefore improved support and an improved guide for the rotation of the shaft.

[0023] In one embodiment variation, the fixed radial wall is in the shape of a partition inserted in the main cavity and blocked in a vertical position, for example by blocking pins attached to the base or to the upper wall of the main cavity 14. In this embodiment, the fixed radial portion has a perimetral sealing element 17 along all four sides. [0024] A further pair of pins 21 acts as a limit position device for the movement of the mobile radial portion 16' of the separation wall 16. Advantageously, said limit position pins 21 are positioned so as to allow rotation of the mobile radial portion 16' by an angle of at least 90° in both directions, in relation to an intermediate neutral position, wherein said mobile radial portion 16' is aligned with the fixed radial portion 16".

[0025] In order to facilitate assembly of the stabiliser device, in one embodiment the main body 10 is composed of two parts, 10' , 10" which can be assembled, for example, by screws.

[0026] In an embodiment particularly suitable for application to a mountain-bike, in other words where the fork 50 is not in close contact with the wheel, being for example a cushioned fork, the upper extremity 26' of the command shaft 26, that is the portion projecting from the body 10, may be attached to the support plate 54 of the arms 56 of the fork 50, so as to be joined to the steering group. For example, said upper extremity 26' of the command shaft 26 is accommodated in a seat 58 made in the support plate 54 and open underneath. The upper extremity 26' is attached to said seat 58 for example by means of a radial dowel 55.

[0027] In one embodiment, the stem 52 of the fork is a tubular element, hollow on the inside, the axial cavity 58' of which also traverses the plate of the fork and is open underneath. In this fork structure, the seat 58 is therefore the terminal part of the axial cavity 58' of the stem of the fork.

[0028] Given that various diameters of fork stems exist in commerce and therefore various diameters of the axial hole of said stem, on the upper extremity 26' of the command shaft 26, an adapter ring 27 is advantageously fitted which adapts the stabiliser device to various stem diameters .

[0029] Consequently, when the stabiliser device 1 is assembled on the steering group, it finds itself in the space defined laterally by the arms of the fork 56, above by the support plate 54 and below by the wheel of the bicycle (figure 5).

[0030] For attachment to the bicycle frame, a bracket 12 positioned below the fork plate extends from the main body, for example having an inclination of about 45°, suitable for being attaching to the oblique element 81 of the bicycle frame which connects the head tube with the hub of the pedals. To enable the stabiliser device to be mounted on bicycles with frames of different shapes and sizes, the attachment bracket 12 is adjustable in length. [0031] In one embodiment variation, particularly suitable for application to on-road bicycles, where the fork is instead in close contact with the front wheel and there is no space for positioning the stabiliser device between the arms of the fork, the device 1 is mounted on the handlebar 90, with the command shaft therefore facing downwards (figure 6). In fact, the steering tube 60, also called handlebar pipe, is a tubular element usually connected to the stem 52 of the fork by a screw 62. The head of the screw acts on a cap which closes the top of said tubular element.

[0032] According to one embodiment, the stabiliser device 1 comprises a modified cap 64 which has the same function as the traditional cap, but a greater extension in height to allow the insertion of the extremity 26' of the command shaft 26 in the same seat as the head of the screw 62 and in such a way as to project, though only slightly, beyond the upper rim of the steering tube 60. In the projecting portion of the cap there is at least one seat for a respective radial dowel 55 blocking the command shaft to the cap 64.

[0033] In this case, the attachment bracket 12' to the bicycle frame 80 extends from the main body, downwards, for example forming an angle of 90°, so as to be connected, for example by an attachment clip, to the horizontal tubular element 82, or crossbar, of the frame .

[0034] It should be noted that in both assembly modes of the device to the bicycle, the command shaft 26 does not cause any significant stress on the main body, in that for its rotation it uses the bearings which permit rotation of the steering group in relation to the head tube 70 of the frame. In effect, the command shaft is configured as an upper or lower extension of the stem of the fork or of the head set.

[0035] Advantageously, for the purposes of further improving sliding of the command shaft in relation to the main body, in the areas of contact of said shaft with the body, therefore at the base and/or upper wall of said body, around the shaft, a self-lubricating plastic ring, such as Darling, is fitted.

[0036] According to a further important aspect of the invention, the through cross-section of the calibrated cross-section duct 22 is adjustable.

[0037] In one embodiment, the two containment chambers 18, 20 communicate through a regulation circuit of the through cross-section of the stabilising fluid comprising an adjustment valve 30. Said adjustment valve has adjustment devices which can be activated by the user, such as a flow regulator pin 31 fitted with a control nut 32.

[0038] More specifically, the adjustment valve 30 has a first aperture 30a connected to a first duct 31 coming from a first containment chamber 18 and a second aperture 30b connected to a second duct 33 coming from the second containment chamber 20.

[0039] The adjustment valve 30 is in any case provided to ensure a minimum flow of the stabilising fluid, and thereby a minimum fluidity of steering, preventing such extreme adjustments as to almost completely block the steering.

[0040] In one embodiment, particularly suitable for racing, in which the stabiliser device is mounted below the fork plate 54, the adjustment valve 30 is made in a separate body from the main body of the device and is positioned on the handlebar, thereby in a position comfortably accessible by the user.

[0041 ] The ducts 31, 33 which take the fluid to the valve are therefore in the form of fine tubes extending from the respective holes 18' , 20' made on the main body 10 in correspondence of the two chambers 18, 20 (figure 3) .

[0042] In one embodiment variation, particularly suitable for mounting the device on the handlebar, the valve body 30' and the fluid conveying ducts 31' , 33' are made directly in the main body of the device, taking advantage of the thickness of the fixed radial portion 16" of the separation wall.

[0043] To prevent accidental manoeuvring of the flow adjustment devices, the latter are fitted with a safety system, for instance requiring a dual activation movement .

[0044] With the steering stabiliser, if an external force suddenly acts on the handlebar, for instance as a result of impervious terrain, a hole or a stone, such blow is absorbed and cushioned thanks to ,the compression of the oil and its consequent transit, at a controlled speed, from one chamber to the other as a result of rotation of the command shaft.

[0045] Without the device, the bicycle would involuntarily swerve, causing the cyclist to fall, if not sufficiently prepared and reactive in contrasting the sudden force on the handlebar.

[0046] Consequently, the stabiliser device proposed, applicable to any bicycle, racing, amateur, road or off- road, increases the stability of the vehicle in any condition of terrain, cushioning the blows and stress to the handlebar caused by holes, furrows and obstacles on the ground, as well as the stress and oscillations conveyed to the frame during particularly intense pedalling. [0047] It should be emphasised however that the steering mechanism is never blocked, there always being a fluidic communication between the two chambers, which makes the steering mechanism fluid with manual steering and at the same time controlled in the case of sudden stress.

[0048] Thanks to the presence of the adjustment valve, more expert athletes may fine tune the steering stabiliser, adapting it for example to the type of terrain or circuit tackled.

[0049] It should be emphasised that the stabiliser, device, being of the rotary type and coaxial to the steering axis, does not influence the steering angle in any way, unlike the linear devices used up to now. In addition the device makes it possible to achieve the desired effect with extremely limited size and weight which do not appreciably influence the weight or appearance of the bicycle .

[0050] The attachment of the main body to the bicycle frame, by means of a bracket, makes it possible to avoid vibrations, play or oscillations, practically making said body an integral part of the frame.

[0051 ] A person skilled in the art may make modifications, adaptations and replacements of elements with others functionally equivalent to the embodiments of the stabiliser device described above so as to satisfy contingent requirements while remaining within the scope of protection of the following claims. Each of the characteristics described as belonging to a possible embodiment may be realised independently of the other embodiments described.

Claims

Claims

1. Steering stabiliser, in particular for bicycles, comprising a main hollow body fitted with attachment devices to the bicycle frame, said body defining inside it a main cavity, in which at least one separation wall extends, dividing said main cavity into at least two containment chambers for a stabilising fluid, said two chambers being in fluidic communication with each other through at least one calibrated cross-section duct, said separation wall having at least one mobile portion able to cause a variation of equal size and opposite direction in the volume of said two chambers wherein said mobile portion of the separation wall is operatively connectable to the steering axis of the bicycle, so that a rotation of said axis causes a displacement of said mobile portion and therefore transit of the stabilising fluid from one containment chamber to the other.

2. Device according to claim 1, wherein said main cavity extends essentially around a main axis of symmetry Y and wherein the hollow body is suitable for being mounted so that said main cavity is coaxial with the steering axis of the bicycle.

3. Device according to claim 2, wherein said main cavity is essentially a cylindrical shape and wherein the separation wall is coplanar to the longitudinal axis of said cavity.

4. Device according to claim 2 or 3, wherein the separation wall comprises a fixed radial portion and a mobile radial portion able to rotate around the longitudinal axis of the main cavity.

5. Device according to claim 4, wherein the mobile radial portion is attached to a command shaft which extends axially in the main cavity of the hollow body and which projects from said body to connect itself to the steering mechanism of the bicycle.

6. Device according to claim 4 or 5, wherein the fixed radial portion is made in one piece with the main body as a radial projection which extends from the inner surface of the main cavity as far as coming into contact with the command shaft.

7. Device according to claim 6, wherein the contact surface of said radial projection with said command shaft is a concave surface complementary to the surface of the shaft, and where at least one longitudinal seat is made in said concave contact surface wherein a sealing element is inserted.

8. Device according to any of the previous claims, wherein the through section of the calibrated through cross-section is adjustable.

9. Device according to claim 8, wherein the two containment chambers communicate through an adjustment circuit of the through section of the stabilising fluid comprising an adjustment valve.

10. Device according to claim 9, wherein the adjustment valve has a first aperture connected to a first duct coming from a first containment chamber and a second aperture connected to a second duct coming from the second containment chamber.

11. Device according to claim 9 or 10, wherein the adjustment valve is a pin valve.

12. Device according to any of the claims from 9-11, wherein the adjustment valve is made in a separate body from the main body and is fluidically connected to the containment chambers of the stabilising fluid by means of respective tubes.

13. Device according to any of the claims from 9-11, wherein the adjustment valve and the connecting ducts of the stabilising fluid to the containment chambers are made in the main body of the device, taking advantage of the thickness of the fixed radial portion of the separation wall.

14. Device according to any of the previous claims wherein the main body comprises limit position devices able to limit the movement of the mobile portion of the separation wall.

15. Device according to any of the previous claims, wherein the mobile portion of the separation wall is free to rotate at an angle of at least 90° in both directions in relation to a neutral position in which it is aligned with the fixed portion of said wall.

16. Device according to any of the previous claims, wherein from the main body a bracket extends suitable for being attached to the oblique element of the bicycle frame which connects the head tube with the hub of the pedals or to the horizontal element or crossbar of the frame .

17. Bicycle comprising a stabilising device according to any of the previous claims.

18. Bicycle according to claim 17, wherein the main body is placed between the two arms of the fork.

19. Bicycle according to claim 19, wherein the command shaft is attached to the upper support plate of the arms of the fork.

20. Bicycle according to claim 19, wherein the upper extremity of the command shaft is inserted in a seat made in the plate of the fork and is blocked in said seat by at least one radial dowel.

21. Bicycle according to claim 20 comprising, in addition, an adapter ring fitted on the upper extremity of the command shaft.

22. Bicycle according to any of the claims from 17-21, wherein the adjustment valve is placed on the handlebar.

23. Bicycle according to claim 17, wherein the device is mounted on the handlebar, with the command shaft facing downwards and operatively connected to the head set.

24. Bicycle according to claim 23, wherein the command shaft is joined to a cap which closes the top of the steering tube and on which the head of the connection screw, of said steering tube to the stem of the fork,