Technical Field

The present invention relates to a vehicle comprising a self-centring mechanism for a wheel of the vehicle.

Background

A vehicle, such as a bicycle or scooter, typically comprises a steering assembly for steering a wheel of the vehicle. As the vehicle moves over a surface, bumps, potholes and other uneven features in the surface may impart forces to the steering assembly. Such forces can adversely affect the stability and control of the vehicle.

Summary

The present invention relates to a vehicle comprising: a frame; a fork arranged to rotate relative to the frame about a rotational axis; a wheel attached to the fork; and a self-centring mechanism for centring a position of the wheel, the self-centring mechanism comprising: a cam; a follower engaged with the cam; and a biasing member for biasing the follower against the cam, wherein: rotation of the fork relative to the frame causes the follower to rotate relative to the cam about the rotational axis; and the cam is shaped such that the follower is biased by the biasing member to a rest position, and rotation of the follower relative to the cam causes the follower to move from the rest position and translate relative to the cam in a direction parallel to the rotational axis against the biasing member.

Optionally, the follower may comprise an elongate member engaged with the cam. Optionally, the elongate member may comprise a longitudinal axis that is perpendicular to the rotational axis. Optionally, a first end of the elongate member may engage a first portion of the cam, and a second end of the elongate member may engage a second portion of the cam. Optionally, at least part of the elongate member may rotate about an axis perpendicular to the rotational axis. Optionally, the elongate member may comprise a rod or pin. Optionally, the follower may comprise a circular crosssection.

Optionally, the follower may comprise a rotatable portion engaged with the cam, and the rotatable portion may be arranged to rotate about an axis perpendicular to the rotational axis. Optionally, the follower may comprise a first rotatable portion engaged with a first portion of the cam and a second rotatable portion engaged with a second portion of the cam, and each of the first rotatable portion and the second rotatable portion may be arranged to rotate about a respective axis perpendicular to the rotational axis. Optionally, the first rotatable portion and the second rotatable portion rotate about a common axis. Optionally, the rotatable portion or each of the first rotatable portion and the second rotatable portion may comprise a bearing. Optionally, the cam may comprise a limiter to limit rotation of the follower relative to the cam to a predefined angle of rotation. Optionally, the cam may comprise a track along which the follower moves. Optionally, the limiter may be provided at an end of the track and/or limit movement of the follower along the track. Optionally, the limiter may extend in a direction parallel to the rotational axis. Optionally, the predefined angle of rotation may be between 30 and 60 degrees from in the rest position.

Optionally, the follower may be arranged to translate relative to the cam within a slot for guiding translation of the follower relative to the cam. Optionally, the fork may comprise the slot. Optionally, the fork may comprise two slots through which the follower extends. Optionally, the two slots may be diametrically opposed about the rotational axis. Optionally, the slot or each slot may extend parallel to the rotational axis. Optionally, the slot or each slot may inhibit rotation of the follower relative to the fork about the rotational axis.

Optionally, the cam may comprise one or more tracks, the follower may engage with and move along the tracks as the follower rotates relative to the cam, and the biasing member may bias the follower against the tracks.

Optionally, the cam may comprise a track having an inflection, the follower may engage with and move along the track as the follower rotates relative to the cam, the biasing member may bias the follower against the track towards the inflection, and the follower may be in the rest position when the follower is located at the inflection. Optionally, the track may comprise a profile having a gradient that is linear or increases in a direction away from the inflection. Optionally, a resistance of the biasing member increases as the follower translates away from the inflection along the rotational axis. Optionally, the track may have a V-shaped or U-shaped profile.

Optionally, the cam may comprise a first track and a second track, each of which are engaged by respective portions of the follower. Optionally, the first track may be diametrically opposed to the second track with respect to the rotational axis. Optionally, the first track and the second track may be distinct such that a respective portion of the follower engages only one of the first track or the second track in response to rotation of the follower relative to the cam. Optionally, the or each track comprises a V-shaped profile.

Optionally, the cam may be annular. Optionally, the cam may comprise an annular body having one or more tracks formed in or on the annular body.

Optionally, the biasing member may be located inside a tube of the fork. Optionally, the biasing member may comprise a spring. Optionally, the biasing member may comprise a coil spring. Optionally, the biasing member may be configured to expand and contract within the fork in a direction parallel to the rotational axis. Optionally, the biasing member engages the follower. Optionally, a biasing force increases when the follower moves from the rest position.

Optionally, the cam may surround a tube of the fork. Optionally, the fork may extend through the cam. Optionally, the fork comprises a tube within which the biasing member is located.

Optionally, the follower may comprise a body moveable within a tube of the fork. Optionally, the body may be constrained by the tube of the fork to prevent tilting of the body within the tube. Optionally, the follower may comprise an elongate member that extends through the body. Optionally, the body may be disc-shaped. Optionally, the biasing member may urge against the body. Optionally, the body may comprise a surface against which the biasing member abuts.

Optionally, the cam may be attached to the inside of a tube of the frame. Optionally, the cam may be attached to the inside of a headtube of the frame.

Optionally, the wheel may be a front wheel of the vehicle.

Optionally, the follower and/or the cam may comprise a metal. Optionally, the metal may be steel.

Optionally, the vehicle is a scooter or a bicycle.

Optionally, the vehicle may comprise handlebars attached to the fork by a steerer.

Optionally, the vehicle may comprise an electric motor for propelling the vehicle, and a battery for supplying electrical power to the electric motor.

Brief Description of the Drawings

Figure 1 is a side view of an example scooter;

Figure 2 is a cross-sectional view through a part of the scooter;

Figure 3 is a perspective view of the part of the scooter, wherein a fork of the scooter is in a first position;

Figure 4 is a further perspective view of the part of the scooter, wherein the fork is in the first position and a frame of the scooter is omitted;

Figure 5 is a perspective view of the part of the scooter, wherein the fork is in a second position;

Figure 6 is a further perspective view of the part of the scooter, wherein the fork is in the second position and the frame of the scooter is omitted;

Figure 7 is a perspective view of a part of an example of a further scooter; and

Figure 8 is a cross-sectional view of the part of the further scooter. Detailed Description

The scooter 10 of Figure 1 comprises a frame 20, a pair of wheels 30,35, and a steering assembly 40.

The frame 20 comprises a headtube 22, a downtube 23 and a deck 24. The downtube 23 interconnects the headtube 22 and the deck 24. The deck 24 forms a platform on which a user stands during use of the scooter 10.

The wheels comprise a front wheel 30 and a rear wheel 35. Each of the wheels 30,35 comprises an axle 31 ,36 about which the wheel rotates. The front wheel 30 is attached to the steering assembly 40, and the rear wheel 35 is attached to the deck 24.

The steering assembly 40 comprises handlebars 41 , a steerer 42, and a fork 43. The steerer 42 interconnects the handlebars 41 and the fork 43. The fork 43 comprises a steerer tube 44 and a pair of blades 45 or legs. Each of the blades 45 comprises a dropout 46 for receiving the axle 31 of the front wheel 30. The fork 43 is fixedly attached the steerer 42 and is rotatably attached to the headtube 22 of the frame 20. As a result, the steering assembly 40 is free to rotate relative to the frame 20.

Referring now to Figure 2, the fork 43 is rotatable attached to the headtube 22 of the frame 20 by a pair of bearings 27,28 and a compression system (not shown). The steerer tube 44 extends through the headtube 22, and the headtube 22 comprises a bearing seat 25,26 at each end of the headtube 22. A bearing 27,28 is then located in each of the seats 25,26. A compression system (not shown), such as a hidden internal compression (HIC), integrated hidden compression (IHC) or standard compression system (SCS) is then used to drive the bearings 27,28 and headtube 22 downward relative to the fork 43, so as to retain the headtube 22 and bearings 27,28 against the steerer tube 44.

The fork 43 rotates relative to the headtube 22 about a rotational axis 49. The front wheel 30 may therefore be steered left and right, using the handlebars 41 , about the rotational axis 49.

In use, the scooter 10 is propelled forwards whilst the user stands on the deck 26 and steers using the handlebars 41. In this particular example, the scooter 10 is propelled by an electric motor 37 located in the hub of the rear wheel 35 and powered by a battery pack 38 located within the deck 24 of the scooter 10. However, the scooter 10 may be propelled by other means. For example, the scooter 10 may be unpowered and is propelled by the user.

During use, the steering assembly 40 rotates relative to the frame 20 in response to an input. This input may be provided by the user of the scooter 10. For example, the user may apply a steering force to the handlebars 41 , which in turn causes the steering assembly 40 to rotate to the right or left (i.e. clockwise or counter-clockwise rotation) about the rotational axis 49. Alternatively, the input may be provided by an external force. For example, as the scooter 10 moves over a surface, bump, potholes and other uneven features in the surface may impart a force on the front wheel 30, thus causing the steering assembly 40 to rotate relative to the frame 20. In another example, the front wheel 30 may experience wobble. Wheel wobble may be arise for a number of reasons, such as wheel imbalance, imperfections or issues in the wheel bearing, or shuddering upon braking. Wheel wobble may be particularly pronounced when there is a relatively light load on the front wheel and/or when travelling at relatively high speeds. These external inputs to the steering assembly 40 may adversely affect the stability and control of the scooter 10. The scooter therefore comprises a selfcentring mechanism 50 to help mitigate these effects and thus improve the stability and control of the scooter 10.

Referring now to Figures 2 to 6, the self-centring mechanism 50 comprises a cam 60, a follower 70, and a biasing member 80.

The cam 60 comprises an annular sleeve or collar that is fixedly attached to the inside of the headtube 22. In this particular example, the cam 60 is a separate element that is attached to the headtube 22. In an alternative example, the cam 60 may form an integral part of the headtube 22. The cam 60 comprises a pair of tracks 62 located on opposite sides of the cam 60. Accordingly, the cam 60 comprises a first track and a second track located on diametrically opposed sides of the cam 60. Owing to the location of the tracks, only one of the tracks 62 is visible in the Figures. However, other than their locations, the two tracks are identical. Each of the tracks 62 has an inverted V-shape profile and comprises an inflection 64 located at a middle of the track, together with a pair of ramped portions 65 located on either side of the inflection 64. The cam 60 further comprises a limiter 67 or end-stop located at each end of each track 62. As explained below in more detail, the limiters 67 act to limit rotation of the follower 70 relative to the cam 60.

The follower 70 comprises a body 72 and an elongate member 74. The body 72 is cylindrical or disc-shaped and is located inside the steerer tube 44 of the fork 43. The body 72 comprises a bore that extends diametrically through a side wall of the body 72. The elongate member 74 comprises a pin having a bearing pressed onto each end of the pin. The diameter of pin is stepped and is smaller at the ends such that the elongate member is of roughly of uniform diameter along its length. The elongate member 74 extends through the bore in the body 72.

The steerer tube 44 comprises a pair of slots 47, each of which extends in a direction parallel to the rotational axis 49. The slots 47 are located on opposite sides of the fork 43 and thus only one of the slots 47 is visible in the Figures. The elongate member 74 of the follower 70 then extends or protrudes through each of the slots 47. The slots 47 are sized such that the elongate member 74 of the follower 70 is constrained from rotating relative to the fork 43 about the rotational axis 49, but is free to translate along the slots 47 in a direction parallel to the rotational axis 49. The biasing member 80 is located within the steerer tube 44 of the fork 43 and applies a biasing force to the follower 70. In this particular example, the biasing member 80 comprises a coil spring, and more particularly a compression spring, that extends between a closed end of the steerer tube 44 and the body 72 of the follower 70. However, other forms of biasing member may be employed, such as a tension spring, a gas spring, or a resilient body (e.g. such as one made of rubber or other elastic material).

The biasing member 80 biases the follower 70 against the cam 60. More particularly, the biasing member 80 biases the ends of the elongate member 74 against the tracks 62 of cam 60. Owing to the profile or shape of the tracks 62, the follower 70 is biased towards the inflections 64 in the tracks 62. When the follower 70 is located at the inflections 64, the follower 70 may be said to be at a rest position or stable position.

When the follower 70 is in the rest position, the fork 43 is aligned centrally (i.e. in a straight-ahead direction) relative to the frame 20. The front wheel 30 is thus centred and the scooter 10 moves in a straight direction when the follower 70 is in the rest position.

The fork 43 may be caused to move relative to the frame 20 in response to an input force (e.g. movement of the handlebars 41 by the user, or an external force imparted to the front wheel 30). When the fork 43 rotates relative to the frame 20, the follower 70 is caused to rotate relative to the cam 60. In particular, the steerer tube 44 of the fork 43 engages the elongate member 74 of the follower 70 that extends through the slots 47 in the steerer tube 44. Consequently, as the fork 43 rotates, the follower 70 is caused to rotate in the same direction about the rotational axis 49. As the follower 70 rotates relative to the cam 60 about the rotational axis, the follower 70 moves along the tracks 62 of the cam 60. In moving along the tracks 62, the follower 70 moves away from the inflections 64 and along the ramped portions 65 of the tracks 62. As a result, the follower 70 translates in a direction parallel to the rotational axis 49 against the biasing force of the biasing member 80. More particularly, the body 72 of the follower 70 translates within the steerer tube 44, and the elongate member 74 translates along the slots 47 in the steerer tube 44. The follower 70 is therefore moved from the rest position against the biasing force of the biasing member 80.

When the input force on the fork 43 is subsequently removed (e.g. should the user relax the force applied to the handlebars 41 or should the external force applied to the front wheel 30 be removed), the biasing force applied by the biasing member 80 causes the follower 70 to return to the rest position. In particular, the follower 70 is moved back along the tracks 62 in the cam 60 by the biasing member 80 until the follower 70 reaches and settles at the inflections 64. In moving along the tracks 62, the follower 70 both rotates about the rotational axis 49 and translates parallel to the rotational axis 49. Upon rotating about the rotational axis 49, the follower 70 causes the fork 43 to rotate relative to the frame 20. The follower 70 therefore returns to the rest position, causing the fork 43 to once again align centrally with the frame 20. The self-centring mechanism 50 therefore causes the fork 43 and thus the steering assembly 40 and the front wheel 30 of the scooter 10 to return to the central position. As a result, the stability and control of the scooter 10 may be improved.

Figures 3 and 4 illustrate part of the scooter 10 with the fork 43 in the central position. Figures 5 and 6 illustrate the same part of the scooter 10 but with the fork 43 rotated to the left. In Figures 4 and 6, the frame 20 has been removed in order that the components of the self-centring mechanism 50 may be viewed. It can be seen in Figure 4 that, with the fork 43 in the central position, the follower 70 is located at the inflections 64 in the tracks 62 (i.e. the follower 70 is at the rest position). In contrast, it can be seen in Figure 6 that, with the fork 43 turned to the left, the follower 70 is moved away from the inflections 64 and along the ramped portions 65 of the tracks 62. In moving along the ramped portions 65, the follower 70 translates downward against the biasing force of the biasing member 80.

As noted above, the cam 60 comprises limiters 67 located at the ends of each track 62. The limiters 67 extend from the ends of the track 62 in a direction parallel to the rotational axis 49. Moreover, the limiters 67 are taller than the elongate member 74 of the follower 70 (i.e. the limiters 67 extend beyond the elongate member 74 in a direction parallel to the rotational axis 49), which prevents the follower 70 from riding over the limiters 67. As the fork 43 rotates relative to the frame 20, the follower 70 moves along the tracks 62 of the cam 60. Upon reaching the end of a track 62, the follower 70 engages a limiter 67. Further rotation of the follower 70 is then prevented by the limiter 67 and thus no further rotation of the fork 43 is possible. The limiters 67 therefore limit rotation of the follower 70 relative to the cam 60, and thus limit rotation of the fork 43 relative to the frame 20. As a result, the steering angle of the steering assembly 40 is constrained by the limiters 67. Excessive steering angles, which can lead to excessive loading of the bearings 27,28 as well as present a safety concern during use, may therefore be prevented. The limiters 67 may be said to limit the steering angle of the steering assembly 40 to a predefined angle range. In the present example, the predefined angle range is around 45 degrees in either direction from the centre position (i.e. the follower 70 is free to rotate by 45 degrees in either direction from the inflections 64). Accordingly, the front wheel 30 of the scooter 10 may be rotated or turned by 45 degrees in either direction. The limiters 67 of the cam 60 may be omitted or unemployed and the steering angle of the steering assembly 40 may be limited, if required, by other means. For example, the headtube 22 and the steerer tube 44 may comprise features to restrict the steering angle.

The elongate member 74 of the follower 70 comprises a bearing located at each end of a pin. Each of the bearings then rotates (about an axis perpendicular to the rotational axis 49) as the follower 70 moves over the cam 60. The provision of bearings reduces wear of the cam 60 and the follower 70. Conceivably, however, the bearings may be omitted or replaced with some other rotatable portion (e.g. a collar or bushing that is free to rotate on the pin). Where the elongate member 74 comprises no bearings or rotatable portions, the elongate member 74 as a whole may rotate as it moves along the tracks 62. Alternatively, the elongate member 74 may slide rather than rotate along the tracks 62. The body 72 of the follower 70 simplifies the assembly of the self-centring mechanism 50 (which is described below) and also helps ensure that the biasing force applied by the biasing member 80 on the follower 70 is move evenly distributed. Nevertheless, the body 72 could conceivably be omitted and the biasing member 80 may act directly on the elongate member 74.

The tracks 62 of the cam 60 have a V-shaped profile. The gradient of the track 62 on either side of the inflection 64 is therefore constant. As a result, the biasing force acting upon the follower 70 increases linearly upon rotation of the follower 70 and the fork 43. The tracks 62 of the cam 60 may have an alternative profile, so as to achieve a different response. For example, the tracks 62 of the cam may have a U-shaped profile such that the gradient of each track 62 increases as the follower 70 moves from the inflections 64.

In order to assemble the scooter 10, and in particular the assembly shown in Figure 2, the lower bearing 27 is inserted onto the steerer tube 44 of the fork 43. The biasing member 80 (e.g. compression spring) is then inserted into the steerer tube 44. The body 72 of the follower 70 is then placed on top of the biasing member 80 and is pressed downward against the biasing force of the biasing member 80 and into the steerer tube 44. The body 72 of the follower 70 is depressed downward until the body 72 is aligned with the slots 47 in the steerer tube 44. The elongate member 74 is then inserted through the slots 47 in the steerer tube 44 and into the bore of the body 72. The body 72 of the follower 70 is then released, causing the biasing member 80 to bias the follower 70 upward until the elongate member 74 abuts the tops of the slots 47 in the steerer tube 44. The subassembly of fork 43, lower bearing 27, follower 70 and biasing member 80 is then inserted into the headtube 22. The lower bearing 27 is seated in the lower seat 25 of the headtube 22, and the elongate member 74 of the follower 70 engages the tracks 62 of the cam 60, which is attached to the inside of the headtube 22. Finally, the upper bearing 28 is inserted over the steerer tube 44 and is seated in the upper seat 28 of the headtube 22, so to arrive at the assembly shown in Figure 2.

A further example of a scooter 100 is shown in Figures 7 and 8. Corresponding features are incremented by 100 but not further discussed in any detail.

In this further example, the components of the self-centring mechanism 150 are essentially unchanged but their arrangement within the headtube 122 and fork 143 are inverted. As with the example described above, the self-centring mechanism 150 comprises a cam 160, a follower 170, and a biasing member 180 (again in the form of a compression spring). Again, the cam 160 is attached to the inside of the headtube 122, the follower 143 comprises an elongate member 174 that extends through slots 147 in the steerer tube 144 of the fork 143, and the biasing member 180 is located within steerer tube 144. In contrast to the example described above, the follower 143 does not include a body in addition to the elongate member 174. Instead, the self-centring mechanism 150 comprises a shim 182 or washer located between the biasing member 180 and the follower 170 to distribute the biasing force more evenly across the follower 170. Owing to the inversion of the components of the self-centring mechanism 150, the biasing member 180 now biases the follower 170 downwards rather than upwards, and the inflection 164 in each of the tracks 162 of the cam 160 corresponds to a nadir rather than an apex in the track 162. In all other respects, the components of the self-centring mechanism 150 are unchanged. For example, the cam 160 continues to comprise tracks 162 along which the follower 170 moves during rotation of the follower 170 relative to the cam 160. Each of the tracks 162 comprises a central inflection 164 that corresponds to a rest position to which the follower 170 is biased by the biasing member 180.

In order to assemble the scooter 100 of this further example, the lower bearing 127 and the upper bearing 128 are seated within the headtube 122. The steerertube 144 of the fork 143 is then inserted through the bearings 127,128 and the headtube 122. In contrast to the example described above, the headtube 122 of this further example comprises a small insertion hole 129 through which the follower 170 is inserted. In order to insert the follower 170, the fork 143 is moved to the centrally- aligned position relative to the headtube 122. This then causes the slots 147 in the steerer tube 144 to align with the insertion hole 129. The follower 170 is then inserted via the insertion hole 129 and through the slots 147 in the steerer tube 144. When fully inserted, the follower 170 drops onto the tracks of the cam 160 and into the rest position. The shim 182 and biasing member 180 (e.g. compression spring) are then inserted into the steerer tube 144. Finally, when the compression system of the scooter 100 is attached to the steerer tube 144 (in Figures 7 and 8, a compression ring 192 and bolt 194 of the compression system are shown), the bolt or fastener 194 of the compression system compresses the biasing member 180 within the steerer tube 144. As a result, the biasing member 180 applies a biasing force to the follower 170.

In each of the examples described above, the cam 60,160 is fixedly attached to the headtube 22,122 and the follower 70,170 rotates with the fork 43,143. In alternative examples, the follower may be fixedly attached to (or formed integrally with) the headtube, and the cam may rotate with the fork. For example, the follower may comprise one or more projections that project radially inward from the headtube, and the cam may comprise a body that surrounds at least part of the steerer tube of the fork. The cam may then be configured such that it rotates together with the steerer tube about the rotational axis, but is free to translate up and down in a directional parallel to the rotational axis. For example, the steerer tube may again comprise one or more slots that extend parallel to the rotation axis, and the cam may comprise one or projections that project into the slots. The cam is then free to translate up and down the slots, whilst rotation of the steerer tube causes the cam to rotate. In this example, the biasing member may comprise a spring that surrounds the steerer tube and is extends between the cam and one of the two bearings.

In the examples described above, the self-centring mechanism 50,150 is housed wholly within the frame 20,120, and in particular the headtube 22,122, of the scooter. As a result, the self-centring mechanism 50,150 does not adversely impact on the aesthetics of the scooter 10,100. Moreover, the self-centring mechanism 50,150 is protected from dirt, water and the like that may be thrown up from the surface. As a result, the robustness and longevity of the self-steering mechanism 50,150 may be improved.

In the examples described above, the self-centring mechanism is employed in a scooter. Owing to the relatively small size of the wheels of a scooter, external forces acting on the front wheel can significantly impact the stability and control of the scooter. The inclusion of a self-centring mechanism is therefore particularly advantageous in a scooter, particularly an electric scooter capable of travelling at relatively high speeds. Nevertheless, the self-centring mechanism described herein may be employed in other vehicles for centring the position of a wheel. For example, the self- centring mechanism may be employed in a bicycle. In another example, the self-centring mechanism may be used to centre the position of a castor of a vehicle.

It is to be understood that any feature described in relation to any one example may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the examples, or any combination of any other of the examples.

Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.