WO2013095148A1

WO2013095148A1 - A bracket shaft assembly, a power assist assembly and a human powered vehicle

Info

Publication number: WO2013095148A1
Application number: PCT/NL2012/050923
Authority: WO
Inventors: Rob Cristian Heinemeijer; Hendricus Johannes Vertegaal
Original assignee: Indes Holding B.V.
Priority date: 2011-12-23
Filing date: 2012-12-24
Publication date: 2013-06-27
Also published as: NL2008040C2; EP2797807A1

Abstract

A bracket shaft assembly (10) that includes a bracket shaft (16) having two free ends (16a, 16b) that are positioned at opposite sides of a central assembly plane (PI) that extends perpendicularly relative to a central bracket shaft axis (Al) around which the bracket shaft is rotatable and that is positioned centrally relative to the free ends. The assembly includes a bearing housing (18), two bearings (20, 22), two fixation nuts (24, 28) and a sensor (32) that is mounted on the bearing housing (18) and that is configured to measure a deformation of the bearing housing and to provide a signal that depends on the amount of deformation. A signal cable (34) that is connected to the first sensor (32) extends through a cable channel (36) in one (24) of the fixation nuts for providing a passage for the signal cable from the interior space of the bracket to the outside. The sensor may be mounted symmetrically relative to the central assembly plane.

Description

Title: A bracket shaft assembly, a power assist assembly and a human powered vehicle.

FIELD

The invention relates to a bracket shaft assembly, a power assist assembly and a human powered vehicle having such a power assist assembly.

BACKGROUND

EP-0 983 934 Al discloses a torque sensor assembly for a bicycle bottom bracket assembly. The torque sensor assembly is intended to provide signals that may be used for controlling an electric drive motor that assists the user of the bicycle when additional drive power is needed. The signals are related to the forces that are exerted by the user on the pedals of the bicycle. In the wording of EP'934, the torque sensor includes an axle supporting member for supporting the bottom bracket axle. The supporting member includes a plurality of sensor mounting locations that are disposed along the length of the supporting member and on which an associated plurality of pressure sensors is arranged. The sensors disclosed in EP'934 are pressure sensors that are mounted on the axle supporting member and that are pushed against a cylindrical member, more particularly a fixation nut of the assembly that surrounds axle support member. Dependent on the force that is exerted on the pedals, the push force that is exerted on the pressure sensor(s) will vary.

EP1 978 343 relates to a torsion-detecting sleeve member to be used in a bicycle bottom bracket assembly. In one of the embodiments, a first adaptor that rotatably supports the crank axle is provided with external screw thread to fasten the adapter in the bottom bracket of the bike frame. A wire insertion groove may be formed in the axial direction of the external peripheral surface of the threaded portion of the first adapter for leading a signal wire to the outside of the first adaptor. Fig. 10 clearly shows the groove. It is problematic to screw the first adaptor in the bottom bracket without damaging the signal wire that extends in the groove.

SUMMARY

A problem of the bottom bracket shaft assembly disclosed in EP'934 is that it is not disclosed how the signals that are generated by the various sensors are transmitted to the controller. Normally, signal cables are connected to the sensors and a hole has to be provided in the bracket of the frame. Such a hole is disadvantageous because dirt and soil may enter the bracket and the bracket shaft assembly may be soiled. When retrofitting a human powered vehicle with a power assist assembly, a hole has to be drilled in the bracket. This leads to bare portions of metal that are not covered with lacquer and that may get rusty. The disclosure of EP'343 described above also is not satisfactory for the reasons mentioned above.

The invention intends to solve or alleviate at least one of the above problems.

To that end, the invention provides a bracket shaft assembly configured to be mounted in a bracket of a human powered vehicle, the bracket being substantially cylindrical and extending from a first end to a second end, bounding an interior space, and having internal screw thread at the first and the second end, the bracket shaft assembly comprising:

• a bracket shaft being rotatable around a central bracket shaft axis and having two free ends that are each configured to mount a crank on it and that are positioned at opposite sides of a central assembly plane that extends perpendicularly relative to the central axis and that is positioned centrally relative to the free ends; • a bearing housing that is hollow and configured to be mounted in the bracket and through which the bracket shaft co-axially extends, the bearing housing having a first end and an opposite second end that are on opposite sides of the central assembly plane;

• a first bearing that is mounted between the bracket shaft and the bearing housing adjacent the first end;

• a second bearing that is mounted between the bracket shaft and the bearing housing adjacent the second end;

· a first fixation nut having a nut wall with external screw thread that is configured to co-operate with the internal screw thread of the bracket adjacent the first end;

• a second fixation nut having a nut wall with external screw thread that is configured to co-operate with the internal screw thread of the bracket adjacent the second end;

• a first sensor that is mounted on the bearing housing and that is configured to measure a deformation of the bearing housing and to provide a signal that depends on the amount of deformation,

• a first electrically conductive signal cable that is connected to the first sensor; and

• a cable channel that extends through the first fixation nut and that is configured to provide a passage for the first signal cable from the interior space of the bracket to the outside.

By virtue of the presence of the cable channel in the first fixation nut, that extends through the fixation nut as opposed to along the external peripheral surface of the fixation nut, the bracket of the human powered vehicle does not have to be provided with a hole. Thus, the bracket assembly in accordance with this embodiment may be easily retrofitted in an existing frame of a human powered vehicle without any damage being done to the frame. The interior space of the bracket will not be soiled and the lacquer of the frame will not be damaged by holes that have to drilled into the bracket. These features may also advantageously be applied with a bottom bracket shaft assembly having a plurality of first sensors that are not mounted symmetrically relative to the central assembly plane. The chance of damaging the signal cable during mounting of the assembly is minimized by virtue of the fact that the signal cable extends through the fixation nut as opposed to along the external peripheral surface thereof.

Another problem of the prior art bracket shaft assembly is that the signal processing of the torque sensor is rather complicated. The forces that are exerted by the user on the pedals that are connected via cranks to the bracket shaft lead to a plurality of signals that vary in time. Even if a force exerted on the left pedal is the same as a force that is exerted on the right pedal, the signals that are generated with the prior art torque sensor assembly differ. Due to the fact that all embodiments that are shown in EP'934 disclose a torque sensor assembly with a plurality of pressure sensors, such an assembly will be rather expensive and the signal

processing that has to be performed by the controller will be complicated. This necessitates a complicated controller that is expensive.

In order to alleviate that problem, an embodiment of the invention may be characterized in that the first sensor, that is configured to measure deformation of the bearing housing, and not as is disclosed prior art a pressure between to parts, is mounted symmetrically relative to the central assembly plane.

By virtue of the fact that, in an embodiment, there may be only a single first sensor, the bracket shaft assembly may be relatively simple and thus cheap. It should be noted that cost is very important factor in the industry of human powered vehicles. By virtue of the fact that the sensor is mounted symmetrically relative to the central assembly plane, the forces exerted on a right pedal and a left pedal will lead to substantially the same signal, at least when the strengths of these forces are the same. By virtue of the fact that there is only a single first sensor that is mounted

symmetrically relative to the central assembly plane, a relatively simple signal processing is necessary to obtain a reliable output signal for controlling an electric drive motor. Such a relatively simple signal processing can be carried out by a relatively simple controller which again leads to a considerable reduction of the costs.

The invention also provides a power assist assembly for a human powered vehicle including:

• a bracket shaft assembly according to the invention;

• an electric drive motor;

• an accumulator that is configured to store and dispatch electric energy and that is connected to the electric drive motor; and

• a controller having an input that is connected to the first sensor and having an output that is connected to the electric drive motor, wherein the controller is configured to control the electric drive motor in dependence of at least an input signal that is provided by the first sensor.

Such a power assist assembly may be relatively cheap and may be retrofitted on an existing human powered vehicle, such as a bicycle, tricycle or go-kart.

The invention also provides a human powered vehicle including:

• a bracket that is substantially cylindrical and extends from a first end to a second end along a length, the bracket having internal screw thread at the first and the second end, wherein the bracket defines a central bracket axis and a central bracket plane that is perpendicular relative to the central bracket axis and positioned so relative to the bracket that the bracket is substantially symmetrical relative to the central bracket plane; • a power assist assembly according to the invention, wherein the bearing housing is fixed and supported relative to the bracket by the first and the second fixation nuts so that the central assembly plane of the bracket shaft assembly is coplanar with the central bracket plane.

By virtue of the fact that central bracket plane is coplanar with the central assembly plane, the first sensor is symmetrically arranged relative to the bracket and, as a consequence, the signals that are provided by the first sensor generated by a force that is exerted on the right pedal will be substantially the same as the signals that are provided by the first sensor generated by a force that is exerted on the left pedal when the strengths of these forces are the same.

Further embodiments of the inventions will be described with reference to some examples that are shown in the figures. It should be noted that the embodiments that are described with reference to the figures are not limited to the examples shown in the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows an exploded perspective view of a first example of a bracket shaft assembly and a bracket;

Fig. 2 shows a perspective view of the first example when mounted in the bracket;

Fig. 3 shows a cross-sectional view of the first example along a vertical plane that includes the bracket shaft axis;

Fig. 4 shows in perspective a detail of the bracket assembly in a mounted condition without showing the bracket;

Fig. 5 shows the same detail as Fig. 4 from a different angle;

Fig. 6 shows an exploded perspective view of a second example of a bracket shaft assembly and a bracket; Fig. 7 shows a perspective view of the second example when mounted in the bracket;

Fig. 8 shows a cross-sectional view of the second example along a vertical plane that includes the bracket shaft axis;

Fig. 9 shows in perspective a detail of the second example in a mounted condition without showing the bracket;

Fig. 10 shows the same detail as Fig. 9 from a different angle without a cover; and

Fig. 11 shows the same detail as Fig. 10 with the cover.

DETAILED DESCRIPTION

The two examples that are shown in the figures have various features in common. These common features will be referred to with the same reference numbers.

The invention provides bracket shaft assembly 10 that is configured to be mounted in a bracket 12 of a human powered vehicle. Such a bracket 12 is substantially cylindrical and extends from a first end 12a to a second end 12b. The bracket 12 bounds an interior space S, and has internal screw thread 14a, 14b at the first and the second end 12a, 12b.

The bracket shaft assembly 10 comprises a bracket shaft 16 that is rotatable around a central bracket shaft axis Al and that has two free ends 16a, 16b that are each configured to mount a crank on it. The free ends 16a, 16b are positioned at opposite sides of a central assembly plane PI that extends perpendicularly relative to the central axis Al and that is positioned centrally relative to the free ends 16a, 16b. The bracket assembly further includes a bearing housing 18 that is hollow and that is configured to be mounted in the bracket 12 and through which the bracket shaft 16 co- axially extends. The bearing housing 18 has a first end 18a and an opposite second end 18b that are on opposite sides of the central assembly plane PI. A first bearing 20 is mounted between the bracket shaft 16 and the bearing housing 18 adjacent the first end 18a and a second bearing 22 is mounted between the bracket shaft 16 and the bearing housing 18 adjacent the second end 18b. The bracket shaft assembly 10 includes a first fixation nut 24 having a nut wall 24a with external screw thread 26 that is configured to co-operate with the internal screw thread 14a of the bracket 12 adjacent the first end 12a. A second fixation nut 28 having a nut wall 28a with external screw thread 30 is configured to co-operate with internal screw thread 14b of the bracket 12 adjacent the second end 12b. The bracket assembly 10 includes a first sensor 32 that is mounted on the bearing housing 18 and that is configured to measure a deformation of the bearing housing 18 and to provide a signal that depends on the amount of deformation. The bracket shaft assembly 10 includes a first electrically conductive signal cable 34 that is connected to the first sensor 32 and cable channel 36 that extends through the first fixation nut 24 and that is configured to provide a passage for the first signal cable 34 from the interior space S of the bracket 12 to the outside. The signal cable 34 may be provided with a connector 64.

As stated before, such a cable channel 36 through the first fixation nut 24 makes it possible to retrofit the bracket shaft assembly 10 in a bracket 12 of an existing human powered vehicle without the necessity to drill a hole in the bracket 12. Thus damage of the vehicle frame is prevented and the interior of the bracket 12 is not exposed to soiling.

In an embodiment, of which both Figs. 1-6 and Figs. 7-11 show an example, the first sensor 32 may be mounted symmetrically relative to the central assembly plane PI. Generally, there will only be a single first sensor 32.

By virtue of the symmetrical arrangement of the first sensor 32, a force of a certain strength exerted on the left pedal will generate

substantially the same signal as a force of the same strength exerted on the right pedal. By virtue of the fact that there is only a single first sensor 32 and by virtue of the central position of the first sensor 32, the signal processing of the signals provided by the first sensor 32 will be relatively simple. Thus the controller 56 that processes the signals and controls an electric drive motor 52 for providing power assist to a user of a human powered vehicle may be relatively simple and thus relatively cheap.

In an embodiment, the first sensor 32 is a piezoelectric sensor. In alternative embodiments, the first sensor may be a force sensitive resistance or a strain gauge. A piezoelectric sensor is beneficial in that it does not need an external electrical source to provide a signal.

In an embodiment of the invention that is exemplified in both the first and second example that are shown in the figures, the first fixation nut 24 and/or the bearing housing 18 may be provided with locking means 38, 40 that prevent rotation of the first fixation nut 24 relative to the bearing housing 18. These locking means 38, 40 prevent that the signal cable 34 will be twisted and damaged during the mounting of the bracket shaft assembly 10 in the bracket. The locking means 38, 40 may be formed by a key 38 on the bearing housing and a key way 40 in the first fixation nut 24 or vice versa. Other locking means that are based on forms that are not rotational- symmetric are feasible as well. For example, the bearing housing 18 may have an hexagonal outer surface adjacent the end of the first fixation nut 24 and the fixation nut 24 may have a corresponding hexagonal inner surface.

Alternatively, a locking pin or locking screw may prevent relative rotation of the first fixation nut 24 and the bearing housing 18.

In yet another embodiment, the locking means may be a very large friction coefficient between engaging surfaces of the first fixation nut 24 and the bearing housing 18. Such a very large friction coefficient may, for example, be obtained by providing the bearing housing 18 adjacent the end of the first fixation nut 24 with a roughened surface such as a knurled surface.

In an embodiment, the locking means may be glue that is provided between the bearing housing 18 and the first fixation nut 24. In an embodiment that is exemplified by the second example shown in figures 6-10, the bracket shaft assembly 10 may include a second sensor 42 that is configured to sense a movement that is indicative of a rotating bracket shaft 16. At least one rotation marker 44 may be provided that moves when the bracket shaft 16 rotates and that is configured to co-operate with the second sensor 42.

Such a second sensor 42 will be connected to the controller 56 as well and provides a signal to controller 56 that is indicative of the fact that the bracket shaft 16 is rotating or is stationary. Thus, the signals provided by the second sensor 42 will inform the controller 56 that the user is, in fact, pedalling and that power assist may be desired, dependent on the signals that are provided by the first sensor 32. This second sensor 42 may prevent that power assist is activated when the user is not pedalling but just exerting a force on one of the pedals without moving the pedals. Instead of a second sensor 42 that is part of the bracket shaft assembly 10, the relevant information about moving pedals may also be obtained via another sensor (not shown) that is not part of the bracket shaft assembly 10. For example a sensor that senses the movement of a chain of human powered vehicle.

In an embodiment, of which an example is shown in figures 6-10, the bracket shaft assembly includes a disc 58 that is mounted on the bracket shaft 16 and on which the at least one rotation marker 44 is mounted.

In an embodiment, of which an example is shown in figures 6-10, the second sensor 42 may be a Hall sensor and the at least one rotation marker 44 may be a permanent magnet. In the example shown in the figures 6-10 the disc 58 carries four permanent magnets that serve as rotation markers 44.

In an alternative embodiment, the second sensor 42 may be an optical sensor and the at least one rotation marker 44 may be an optical mark such as a dark line on a light background or a translucent hole. To that end, the disc 58 may have a plurality of dark lines that extend radially and a light coloured background. Alternatively, the disc 58 may be provided with one or more translucent holes.

In an embodiment, of which an example is shown in figures 6-10, the bracket shaft assembly 10 may include a second electrically conductive signal cable 46 that is connected to the second sensor 42. In an embodiment, the second sensor 42 may be mounted on a flange 48 that is an integral part of the first fixation nut 24. An example of such an embodiment is shown in figures 6-10. In this example, the second signal cable 46 is also provided with a connector 64. This example also includes a cover 60 that engages the flange 48 and that defines a chamber 62 in which the disc 58 is

accommodated and in which the second sensor 42 is present. Thus soiling of the disc 58 and the second sensor 42 may be prevented.

In an embodiment of which an example is shown in figures 6-10, the flange 48 may include a second cable channel 50 that is configured to provide a passage for the first and the second signal cable 34, 46. Thus both the first signal cable 34 connected to the first sensor 32 and the second signal cable 46 connected to the second sensor 42 may be guided to a desired side of the flange 48 that is outside the chamber 62.

In an embodiment, the bracket shaft assembly may include an electronic module that is mounted in or on one of the bracket housing 18, the first fixation nut 24, possibly on the flange 48 thereof, and the second fixation nut 28. Preferably, the electronic module is mounted on the flange 48 of the first fixation nut 48 so that rotation of the fixation nut 24 does automatically cause a corresponding rotation of the electronic module. Thus, the signal cables 34, 46 that connect the sensors 32, 42 with the electronic module do not have to accommodate a relative displacement between the sensors and the electronic module. This is of high importance during mounting of the assembly in the bracket because it makes mounting easy and the chance of disrupting the connection between the sensors 32, 42 and the electronic module during mounting is minimized. The electronic module includes an input that is connected to the first sensor 32 and, optionally, to the second sensor 42 if present. The electronic module further has an output for connecting the module to a controller 56. The electronic module is configured to process the signals produced by the at least one sensor 32, 42 to bring them in a format that is compatible with the controller 56. Thus, a controller 56 that is available in the market may be used to further process the signals that are provided by the electronic module. The controller 56 may control a power assist motor on the basis of the signals provided by the electronic module. Additionally, the electronic module may be configured to combine the signals of the first sensor 32 and the second sensor 42 and optionally any additional sensors to a modulated signal that may be transferred over a single cable 34 instead of two or more cables. This provides the additional advantage that diameter the cable channels 36 and/or 50 may be kept small.

In order to further optimize the uniformity of the signals provided by the first sensor 32, the bearing housing 18 of an embodiment of the bracket shaft assembly 10 may be symmetrical relative to the central assembly plane PI as well. To further optimize the uniformity of the signals of the first sensor 32 that are generated as a consequence of the forces that are exerted on the left and the right pedal, the first and the second bearing 20, 22 may be on opposite sides of the central assembly plane PI and positioned symmetrically relative to each other vis-a-vis the central assembly plane PI.

In an embodiment, the bracket shaft assembly 10 may include a mark 66 on a part of the bracket shaft assembly 10 that is visible from the outside when the bracket shaft assembly 10 is mounted in a bracket 12. Fig. 5 shows an example of a positioning mark 66 on the first fixation nut 24. Fig. 11 shows an example of a positioning mark 66 on the cover 60. The rotational position of the part that includes the positioning mark 66 must be fixed relative to the rotational position of the first sensor 32 so that, when mounting the bracket shaft assembly 10 in the bracket 12, the rotational position of the positioning mark 66 is indicative of the rotational position of the first sensor 32. An advantage of this embodiment is that the rotational position of the first sensor 32 relative to the bracket 12 may be chosen optimally. An optimal choice is, for example, a position on the bearing housing 18 that has the greatest distance from a virtual plan that includes the axis Al of the shaft and that is perpendicular to the direction of the greatest force that is exerted on the pedals of a crank system that is connected to the bracket shaft assembly 10. This is because at those positions of the bearing housing 18 a maximum deformation of the bearing housing 18 occurs when the maximum force is exerted on a pedal. For a bicycle, in which the greatest force on the pedals is exerted in a substantial vertical direction, said virtual plane would extend substantially

horizontally. The positions of the bearing housing 18 that have the greatest distance from the virtual horizontal plane are vertically above and vertically below the axis Al of the bracket shaft 16. Consequently, for a bicycle, or any other human powered vehicle in which the greatest force on the pedals is exerted substantially vertically, the first sensor 32 is preferably positioned vertically above or vertically under the central axis Al. In the examples shown in the figures, this can be achieved by positioning the positioning mark 66 in a top position or, alternatively in a bottom position.

In an embodiment, the bracket shaft assembly may include a sensor of the acceleration type that is configured for sensing acceleration and inclination of a vehicle in which the bracket shaft assembly is mounted. The third sensor of the acceleration type may, for example, be a gyroscopic sensor. A controller 56 that receives input from the various sensors 32, 42 including the acceleration type sensor (not shown), may be configured to control an electric drive motor 52 to provide additional power assist when an upward inclination is detected. The controller 56 may also be configured to control the electric drive motor 52 to the effect that the power assist is diminished when an acceleration of the vehicle is detected by the

acceleration type sensor. Vice versa, the controller 56 may also be

configured to control the electric drive motor 52 to the effect that the power assist is increased when a deceleration of the vehicle is detected by the acceleration type sensor. The acceleration type sensor may be mounted on the bracket shaft assembly 10. Alternatively, the acceleration type sensor may be mounted on any other part of the human powered vehicle. For example, the acceleration type sensor may be housed in a housing of the controller 56 or in a housing of an accumulator 54. It should be noted that the embodiment with the acceleration type sensor may also be applied in combination with conventional bracket shaft assemblies 10, that is, a bracket shaft assembly 10 that includes the features of claim 1 but that does not include a cable channel 36 that extends through the first fixation nut 24 and that is configured to provide a passage for the first signal cable 34 from the interior space S of the bracket 12 to the outside. A bracket shaft assembly including the acceleration type sensor disclosure as described above may be applied independently of the present invention and may be subject of a divisional application.

The bracket shaft assembly 10 of which various embodiments are described above may be part of a power assist assembly for a human powered vehicle. The power assist assembly may be sold as a kit of parts. The power assist assembly additionally includes an electric drive motor 52 and a controller 56. In an embodiment, the electric drive motor 52 may be a wheel hub motor. In an embodiment, the power assist assembly may include a wheel with such a wheel hub motor. The power assist assembly further includes an accumulator 54 that is configured to store and dispatch electric energy and that is connected to the electric drive motor 52. The controller 56 has an input that is or may be connected to the first sensor 32 and an output that is or may be connected to the electric drive motor 52. The controller 56 is configured to control the electric drive motor 52 in dependence of at least an input signal that is provided by the first sensor 32.

When the bracket shaft assembly 10 also includes a second sensor 42, the controller 56 may also include an input that may be connected to the second sensor 42 and the controller 56 may be configured to control the electric drive motor 52 in dependence of at least input signals that are provided by the first sensor 32 and the second sensor 42.

The invention also provides a human powered vehicle including a bracket 12 that is substantially cylindrical and that extends from a first end 12a to a second end 12b. The bracket 12 may have internal screw thread 14a, 14b at the first and the second end 12a, 12b. The bracket 12 defines a central bracket axis A2 and a central bracket plane P2 that is perpendicular relative to the central bracket axis A2 and positioned so relative to the bracket 12 that the bracket 12 is substantially symmetrical relative to the central bracket plane P2. The human powered vehicle additionally includes a power assist assembly as described above. The bearing housing 18 is fixed and supported relative to the bracket 12 by the first and the second fixation nuts 24, 28 so that the central assembly plane PI of the bracket shaft assembly 10 is coplanar with the central bracket plane P2. Such a coplanar mounting of the bracket shaft assembly 10 in the bracket 12 may further optimize the uniformity of the signals that are produced by the first sensor 32 as a consequence of forces that are exerted on the right and the left pedal of the human powered vehicle.

As explained above, in an embodiment, of which two examples are shown in the figures, the first sensor 32 may be positioned vertically above or vertically under the axis Al of the bracket shaft 16. In case of a bicycle or any other human powered vehicle in which the maximum force on the pedals has a substantially vertical direction, the deformation of the bearing housing 18 is maximal at these positions. Consequently, the amplitude of the signal that will be produced by the first sensor 32 will be maximal when the first sensor 32 is positioned vertically above or below the axis Al of the bracket shaft 16.

In an embodiment, the central bracket axis A2 may be parallel to the central bracket shaft axis Al. In a special configuration of such an embodiment, the central bracket axis A2 may co-axial with the central bracket shaft axis Al. In the non-co-axial embodiment with the parallel configuration of axes Al and A2, the position of the central bracket shaft axis Al may, in an embodiment be variable relative to the position of the bracket axis A2. This may be used for tightening a chain of the human powered vehicle. Examples of human powered vehicles are a bicycle, a tricycle and a go-cart.

A bracket shaft assembly 10 as disclosed may be provided in various variants. For example, variants may be provided in which the difference between the variants is determined by length of the bracket shaft 16 and the length of bearing housing 18. Additionally, or alternatively, the difference between the variants may be determined by the diameters of the bearing housing 18, the fixation nuts 24, 26 and the bearings 20, 22.

Although illustrative embodiments of the present invention have been described above, in part with reference to the accompanying drawings, it is to be understood that the invention is not limited to these embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. Reference

throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

Furthermore, it is noted that particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner to form new, not exphcitly described embodiments. The reference numbers that are used throughout the detailed description and the claims should not be construed to limit the description of the various embodiments.

Claims

CONCLUSIES

1. A bracket shaft assembly (10) configured to be mounted in a bracket (12) of a human powered vehicle, the bracket (12) being

substantially cylindrical and extending from a first end (12a) to a second end (12b), bounding an interior space (S), and having internal screw thread (14a, 14b) at the first and the second end (12a, 12b), the bracket shaft assembly (10) comprising:

• a bracket shaft (16) being rotatable around a central bracket shaft axis (Al) and having two free ends (16a, 16b) that are each configured to mount a crank on it and that are positioned at opposite sides of a central assembly plane (P 1) that extends perpendicularly relative to the central axis (Al) and that is positioned centrally relative to the free ends (16a, 16b);

• a bearing housing (18) that is hollow and configured to be

mounted in the bracket (12) and through which the bracket shaft (16) co-axially extends, the bearing housing (18) having a first end (18a) and an opposite second end (18b) that are on opposite sides of the central assembly plane (P 1);

• a first bearing (20) that is mounted between the bracket shaft (16) and the bearing housing (18) adjacent the first end (18a);

• a second bearing (22) that is mounted between the bracket shaft (16) and the bearing housing (18) adjacent the second end (18b);

• a first fixation nut (24) having a nut wall (24a) with external screw thread (26) that is configured to co-operate with the internal screw thread (14a) of the bracket (12) adjacent the first end (12a); a second fixation nut (28) having a nut wall (28a) with external screw thread (30) that is configured to co-operate with the internal screw thread (14b) of the bracket (12) adjacent the second end (12b);

a first sensor (32) that is mounted on the bearing housing (18) and that is configured to measure a deformation of the bearing housing (18) and to provide a signal that depends on the amount of deformation,

a first electrically conductive signal cable (34) that is connected to the first sensor (32);

a cable channel (36) that extends through the first fixation nut (24) and that is configured to provide a passage for the first signal cable (34) from the interior space (S) of the bracket (12) to the outside.

2. The bracket shaft assembly according to claim 1, wherein the first sensor (32) is mounted symmetrically relative to the central assembly plane

(Pi).

3. The bracket shaft assembly according to claim 1 or 2, wherein the first fixation nut (24) and/or the bearing housing (18) are provided with locking means (38, 40) that prevent rotation of the first fixation nut (24) relative to the bearing housing (18).

4. The bracket shaft assembly according to claim 3, wherein the locking means (38, 40) include:

• a key (38) on the bearing housing and a key way (40) in the first

fixation nut (24) or vice versa; • a very large friction coefficient between engaging surfaces of the first fixation nut (24) and the bearing housing (18), for example, by providing the bearing housing (18) adjacent the end of the first fixation nut (24) with a roughened surface such as a knurled surface; or

• glue that is provided between the bearing housing (18) and the first fixation nut (24).

5. The bracket shaft assembly according to any one of the preceding claims, including:

• a second sensor (42) that is configured to sense a movement that is indicative of a rotating bracket shaft (16); and

• at least one rotation marker (44) that moves when the bracket shaft (16) rotates and that is configured to co-operate with the second sensor (42).

6. The bracket shaft assembly according to claim 5, including:

• a disc (58) that is mounted on the bracket shaft (16) and on which the at least one rotation marker (44) is provided.

7. The bracket according to claim 5 or 6, wherein the second sensor (42) is a Hall sensor and wherein the at least one rotation marker (44) is a permanent magnet.

8. The bracket shaft assembly according to claim 5 or 6, wherein the second sensor (42) is an optical sensor and wherein the at least one rotation marker (44) is an optical mark such as a dark line on a light background or a translucent hole.

9. The bracket shaft assembly according to any one of claims 5-8, including:

• a second electrically conductive signal cable (46) that is connected to the second sensor (42).

10. The bracket shaft assembly according to any one of claims 5-9, wherein the second sensor (42) is mounted on a flange (48) that is an integral part of the first fixation nut (24).

11. The bracket shaft assembly according to any one of the preceding claims, including the combination of features of at least claims 2, 9 and 10, wherein the flange (48) includes a second cable channel (50) that is configured to provide a passage for the first and the second signal cable (34, 46).

12. The bracket shaft assembly according to any one of the preceding claims, including:

• an electronic module that is mounted in or on one of the

bracket housing (18), the first fixation nut (24) and the second fixation nut (28), wherein the electronic module includes an input that is connected to the first sensor (32) and, optionally, to the second sensor (42) if present, and having an output, the electronic module being configured to process the signals produced by the at least one sensor (32, 42) to bring them in a format that is compatible with a controller (56).

13. The bracket shaft assembly according to any one of claims 1-12, wherein the bearing housing (18) is symmetrical relative to the central assembly plane (PI).

14. The bracket shaft assembly according to any one of claims 1-13, wherein the first and the second bearing (20, 22) are on opposite sides of the central assembly plane (PI) and positioned symmetrically relative to each other vis-a-vis the central assembly plane (PI).

15. The bracket shaft assembly according to any of the preceding claims, including:

• a positioning mark (66) on a part of the bracket shaft assembly that is visible from the outside when the bracket shaft assembly is mounted in a bracket (12), the rotational position of the part being fixed relative to the rotational position of the first sensor (32) so that, the rotational position of the positioning mark (66) is indicative of the rotational position of the first sensor (32).

16. The bracket shaft assembly according to any one of the preceding claims, including:

• a sensor of the acceleration type configured for sensing acceleration and inclination of a vehicle in which the bracket shaft assembly is mounted.

17. A power assist assembly for a human powered vehicle including:

• a bracket shaft assembly (10) according to any one of the

preceding claims;

· an electric drive motor (52);

• an accumulator (54) that is configured to store and dispatch electric energy and that is connected to the electric drive motor (52); and • a controller (56) having an input that is connected to the first sensor (32) and having an output that is connected to the electric drive motor (52), wherein the controller is configured to control the electric drive motor (52) in dependence of at least an input signal that is provided by the first sensor (32).

18. A human powered vehicle including:

• a bracket (12) that is substantially cylindrical and extends from a first end (12a) to a second end (12b), the bracket (12) having internal screw thread (14a, 14b) at the first and the second end (12 a, 12b), wherein the bracket (12) defines a central bracket axis (A2) and a central bracket plane (P2) that is perpendicular relative to the central bracket axis (A2) and positioned so relative to the bracket that the bracket (12) is substantially symmetrical relative to the central bracket plane (P2);

• a power assist assembly according to clam 17, wherein the

bearing housing (18) is fixed and supported relative to the bracket (12) by the first and the second fixation nuts (24, 28) so that the central assembly plane (PI) of the bracket shaft assembly (10) is coplanar with the central bracket plane (P2).

19. The human powered vehicle according to claim 18, wherein the first sensor (32) is positioned vertically above or vertically under the central axis (Al).

20. The human powered vehicle according to any one of claims 18-19, wherein the human powered vehicle is a bicycle, a tricycle or a go-cart.