WO2011038481A1

WO2011038481A1 - Wheel hub assembly with opto-mechanical torque sensing system

Info

Publication number: WO2011038481A1
Application number: PCT/CA2010/001362
Authority: WO
Inventors: Philipp Annen
Original assignee: Philipp Annen
Priority date: 2009-10-02
Filing date: 2010-09-01
Publication date: 2011-04-07

Abstract

A wheel hub assembly having a wheel hub mounted for undergoing rotation in a given direction, a drive mechanism mounted for undergoing rotation in the given direction in response to an input drive torque applied to the drive mechanism, a coupling mounted to drive mechanism for undergoing rotation therewith and adapted to couple the drive mechanism to the wheel hub so as to undergo angular deflection relative to the wheel hub and concurrently transform the input drive torque received from the drive mechanism to an output drive torque applied to the wheel hub, and an opto-mechanical torque sensing system adapted to produce a reflected ray of light related to the angular deflection of the coupling, measure the intensity of reflected light, and generate an output related to the input drive torque applied to the drive mechanism.

Description

WHEEL HUB ASSEMBLY WITH OPTO-MECHANICAL TORQUE SENSING SYSTEM Technical Field

The present invention generally relates to wheel hub assemblies, and more specifically, is concerned with an opto-mechanical torque sensing system in a wheel hub assembly that may be driven by one or more sources of power, such as a wheel hub assembly used in a rider and electrically propelled vehicle.

Background Art

Rider-propelled vehicles, such as bicycles, employing proportionally assisted (force coupled) motor drive wheel hubs receive rotary forces from both the motor and from the rider's torque on the pedals transmitted to the wheel hub. In order to properly and safely mix these two forces, a means to reliably detect the pedal torque is necessary in order to govern the motor output appropriately.

Known prior art methods used to detect pedal torque input for proportionally assisted motor drives commonly include the use of strain gauges such as demonstrated in US Patent 6851497, US Patent 68661 1 1 and US Patent Application Publication 2008/0103030. Strain gauges employ a thin metallic resistance bridge that detect slight deformations in an axle or other element under stress by the pedals, and translate this torque into a signal that governs the motor output in relation to the amount of pedal torque input. Strain gauge torque sensors are commonly used with or in connection with a standard freewheel type rear wheel where the pedal force is detected by contact deformation of the bottom bracket axle or from deformation of the wheel components, such as an axle. When employing common prior art pedal torque sensors with newer cassette style freewheels however, contact deformation techniques have been shown to be unreliable, therefore a non-contact torque sensing solution is needed.

Another prior art method is the use of rotational speed sensors that employ photointerrupter and or photoreflector rotating discs with compatible optical or magnetic sensors as shown in US Patent 6125959. This method employs non-contact detection of the rotational speed of a motor in relation to the pedal input, but does not detect pedal torque.

I Disclosure of Invention

In one aspect, the present invention is directed to a wheel hub assembly having a wheel hub mounted for undergoing rotation in a given direction about an axle and a drive mechanism mounted for undergoing rotation in said given direction in response to an input drive torque applied to said drive mechanism, wherein said wheel hub assembly is characterized by a coupling mounted to said drive mechanism for undergoing rotation therewith and adapted to couple said drive mechanism to said wheel hub so as to undergo angular deflection relative to said wheel hub about said axle and concurrently transform said input drive torque received from said drive mechanism to an output drive torque applied to said wheel hub; and an optomechanical torque sensing system adapted to produce a reflected ray of light correlated to the angular deflection of said coupling relative to said wheel hub, measure the amount of reflected light, and generate an output correlated to said input drive torque applied to said drive mechanism.

In one aspect, the present invention is directed to a rider-propelled vehicle having a wheel hub mounted for undergoing rotation in a given direction about an axle and a rider-operated rotatable drive mechanism mounted for undergoing rotation in the given direction in response to an input drive torque applied to the drive mechanism, wherein the rider-propelled vehicle is characterized by a coupling mounted to the drive mechanism for undergoing rotation therewith and adapted to couple the drive mechanism to the wheel hub so as to undergo angular deflection relative to said wheel hub about said axle and concurrently transform the input drive torque received from the drive mechanism to an output drive torque applied to the wheel hub, and an opto- mechanical torque sensing system adapted to produce a reflected ray of light correlated to the angular deflection of the coupling relative to said wheel hub, measure the amount of reflected light, and generate a output correlated to the input drive torque applied to the drive mechanism.

In another aspect, the present invention is directed to a rider-propelled vehicle having an axle, a wheel hub mounted for undergoing rotation about the axle in a given direction, a drive motor housed inside the wheel hub and coupled between the wheel hub and the axle and operable to cause rotation of the wheel hub about the axle, and a rider-operated drive mechanism mounted for undergoing rotation about the axle in the given direction in response to an input drive torque applied to the drive mechanism, wherein the rider-propelled vehicle is characterized by a coupling mounted to the drive mechanism for undergoing rotation therewith and being disposed inside the wheel hub where the coupling couples the drive mechanism to the wheel hub so as to undergo angular deflection relative to said wheel hub about the axle and concurrently transform the input drive torque received from the drive mechanism to an output drive torque applied to the wheel hub, and an opto-mechanical torque sensing system adapted to produce inside the wheel hub a reflected ray of light correlated to the angular deflection of the coupling relative to said wheel hub, measure inside the wheel hub the amount of reflected light, generate inside the wheel hub an output correlated to the input drive torque applied to the drive mechanism, and transmit the output from inside to outside of the wheel hub.

Brief Description of the Drawings

In the following detailed description, reference will be made to the attached drawings in which:

Fig. 1 shows a side cutaway view of an exemplary embodiment of a non-contact opto-mechanical torque sensing system of the present invention, shown integrated in a motor drive wheel hub.

Fig. 2 shows a side closeup cutaway view of the torque sensing system of Fig. 1 , showing the torque sensing elements of the system.

Fig. 3a shows a facing view of one of the torque sensing elements of the system of Fig. 1 in the form of a registration disc.

Fig. 3b shows a facing view of another of the torque sensing elements of the system of Fig. 1 in the form of a deflection disc.

Fig. 3c shows a side perspective view of both the deflection and registration discs of Figs. 3a and 3b in order to illustrate how torque deflection is sensed by an optical sensor of the system of Fig. 1.

Fig. 3d shows a partial closeup facing view of the deflection disc in a state of zero deflection showing the sensor's viewpoint of the registration disc.

Fig. 3e shows a partial closeup facing view of the deflection disc in a state of some measurable deflection showing the sensor's viewpoint of the registration disc. Fig. 4 shows a side perspective view of the wheel hub showing its cassette freewheel body and the splined end of the torque bushing.

Fig. 5 shows a functional block diagram of an exemplary embodiment of electrical and opto-mechanical elements of the system.

Fig. 6 shows a combined torque deflector and registration disc in the form of a spider disc.

Mode(s) for Carrying Out the Invention

Referring now to Figs. 1 and 2 of the drawings, there is illustrated an exemplary embodiment of a non-contact opto-mechanical torque sensing system of the present invention, generally designated 10, which is force coupled to a brushless DC drive motor 1 1 contained in a wheel hub 12. For the sake of brevity the non-contact optomechanical torque sensing system 10 hereafter is referred to as the torque sensing system 10.

Elements of the wheel hub 12 basically include a freewheel-side plate 16 and a motor-side plate 18, each fastened to the circumference of the hub rim 14 by means of plate bolts 20. The hub rim 14 also includes spoke flanges 22 with the necessary number of spoke holes 78 to accommodate spokes which attach to the wheel rim (both not shown) and together constitute a motor hub driven rear bicycle wheel hub 12.

Elements of the brushless drive motor 1 1 basically include a ring of permanent magnets 24, a ring of electromagnets 26, an armature 28, and a central stationary axle 30. Arms of the armature 28 are affixed on and radiate from the axle 30. A central hole in the motor-side plate 18 supports a bearing race 32 and one end of the axle 30 as shown. A central hole in the freewheel-side plate 16 supports a bushing/bearing 34 (see Fig. 2), and accommodates a splined end 64 of a torque bushing 62 which connects to a cassette freewheel body 66, including the other end of the axle 30. The bushing/bearing 34 may be either a bearing race 32 similar to that used for the motor- side plate 18, or may be a secondary bushing which fills the gap in the body of the torque bushing 62. The armature 28 supports the ring of electromagnets 26 at its distal end. The ring of permanent magnets 24 are affixed to the inside of the hub rim 14, and together with the electromagnets 26 thus form the basic functional elements of the brushless DC drive motor 1 1 , as commonly employed in bicycle rear wheel motor hubs. Power that energizes the electromagnets 26 and which drives the motor 11 is supplied either via a PCB 38 or directly from a power/data cable 36 which connects to a power source 72 and a controller 70 of the torque sensing system 10 (see Fig. 5), by passing through a keyway 74 as shown. The PCB 38 is attached to and supported by the armature 28 by means of the PCB mounts 40.

Elements of the torque sensing system 10 basically include an optical emitter 42 and an optical sensor 44, supported for example by the PCB 38, and also a deflection disc 48 and a registration disc 52. The emitter 42 may be, for example, a light emitting diode or a diode laser, and may emit light in the infra-red, visible and/or ultraviolet region of the spectrum. The emitter may comprise multiple light sources, which may emit light of nominally the same wavelength, of multiple wavelengths or of a spread of wavelengths covering a range. The emitter 42 emits a ray 46 through a top aperture 50 of the deflection disc 48 which bounces off any reflective segments 56 (see Fig. 3a) on the registration disc 52 and returns that light to the sensor 44. The deflection disc 48 is affixed to the torque bushing 62, which is affixed to a torque deflector 60 with elastic properties which, in turn, is affixed to the inside of the freewheel-side plate 16 of the wheel hub 12. The registration disc 52 is supported by and affixed to disc mounts 54 on the inside of the freewheel-side plate 16.

Also, as shown in Fig. 1 , freewheel elements include the splined end 64 of the torque bushing 62 which thereby connects to and is driven by the cassette freewheel body 66. The cassette freewheel body 66 rotates around the axle 30 on bearing races 32 and supports a multiplicity of cassette style sprocket sets 68 which provide the means by which input drive torque is applied by a rider to the wheel hub 12 and the deflection disc 48 via the torque deflector and bushing 60, 62.

Fig. 3a shows the registration disc 52 with its white reflection segments 56 alternating with its black absorptive segments 58. Fig. 3b shows the diffusive black deflection disc 48 with a multiplicity of apertures 50 which permit a ray 46 from the optical emitter 42 to pass through the top aperture 50 and return to the optical sensor 44 (see Figs. 1 , 2, & 3c). Fig. 3c shows how torque deflection is sensed by non- contacting interaction of the deflection and registration discs 48, 52 with the optical emitter and sensor 42, 44 (note: Fig. 3c only shows the minimum optical segments 56, 58 and apertures 50 to illustrate the basic principle; the full number of segments 56, 58 and apertures 50 are shown in Figs. 3a/b). White refers to an ideal maximum diffuse optical reflectance and black refers to an ideal minimum reflectance (or maximum optical absorbance). In an applied embodiment any pairing with a defined difference in optical reflectance can be utilized to sense torque changes. Any number of matching deflection disc apertures and registration disc optical segments can be utilized with the limits being manufacturability and desired radial deflection (for example, about two degrees). The radial deflection may be limited by a mechanical end stop if fitted. The optically defined apertures and corresponding reflectance targets are not limited to the described segment shape but can take on a multitude of shapes and sizes to achieve a desired radial deflection based difference in overall reflectance. The selection of shapes can be utilized to achieve desired sensing responses not limited to create linear, exponential or custom defined relationships between the applied torque and the measured optical reflectance.

Fig. 3d shows the deflection disc 48 covering the registration disc 52 as seen from the viewpoint of the optical sensor 44. The white reflective segments 56 and the black absorptive segments 58 are completely and only visible to the optical sensor 44 through each aperture 50 of the deflection disc 48. The deflection disc 48 in Fig. 3d is in a state of zero deflection 76. The actual deflection disc 48 is completely diffuse black (represented by speckling) in the full implementation so that the optical sensor 44 will only detect light from the deflected segment on the registration disc 52, and will not detect any unwanted light reflections from the deflection disc 48.

Fig. 3e shows the registration disc 52 as seen through the deflection disc 48, with the latter rotating torque-wise to produce a state of deflection 76 measurable by the optical sensor 44.

Fig. 4 shows a side perspective view of the wheel hub 12 showing its freewheel- side plate 16 with its cassette freewheel body 66 and the splined end 64 of the torque bushing 62. Plate bolts 20 fasten the freewheel-side plate 16 to the hub rim 14, with its spoke flanges 22 and spoke holes 78.

Fig. 5 shows a functional block diagram of the torque sensing system 10. The torque sensor is formed by the optical emitter 42 and sensor 44 on the PCB 38, the registration disc 52 attached to the freewheel-side plate 16 of the wheel hub 12, and the deflection disc 48 attached to the cassette freewheel body 66 via the torque bushing 62 and also attached to the freewheel-side plate 16 of the wheel hub 12 via the torque deflector 60. The torque sensing system 10 also may include the controller 70 and power supply 72. Referring to Figs. 1 , 2 and 5, a rider-operated rotatable drive mechanism comprises a cassette freewheel body 66 that spins in the same direction as the wheel hub 12 about the axle 30. A rider-operated rotatable drive mechanism may additionally comprise a sprocket set 68 together with a cassette freewheel body 66 that spin together in the same direction as the wheel hub 12 about the axle 30. Note that a sprocket set is not essential for the torque sensor. The drive mechanism is able to angularly displace relative to freewheel-side plate 16 of the wheel hub 12 due to attachment thereto of the drive mechanism via a coupling made up of torque deflector and bushing 60, 62. As the drive mechanism is subject to a rider-applied torque, or more specifically an input drive torque at the cassette freewheel body 66, the deflection and registration discs 48, 52 of the torque sensor are angularly displaced relative to each other and interact with the ray 46 to produce a measurable deflection 76 (see Figs. 3e/d) that is sensed by the optical sensor 44 and outputted as a torque sensor analog electrical signal which is routed through the PCB 38 to the controller 70 via the power/data cable 36. The torque sensor electrical signal provides one of the inputs to the controller 70 which are used to regulate the power source 72. Torque sensing data provided by the input electrical signal from the torque sensor in conjunction with user input data are used by the controller 70 to apply the appropriate power to the motor 1 1 via the power source 72.

The exemplary embodiment of the torque sensing system 10 will now be described in more detail below.

The torque sensing system 10 is coupled with the brushless drive motor wheel hub 12 which is capable of accepting a variety of bicycle industry standard cassette freewheel gear clusters (or driven sprocket sets 68) on the chain drive side. The drive motor wheel hub 12 is "force coupled", which means that it can be driven either by powering the motor 1 1 , or by means of a rider applying pedal torque to the installed freewheel, or both combined. Force coupling control for the cassette freewheel body 66 is achieved by means of the above-described torque sensing elements of the system 10 which detect the amount of radial deflection relating to the torque supplied by the rider, and transmit that data to the controller 70 of the system 10, which, depending on its programmable gain ratio and desired response characteristics, determines the amount of force supplied by the motor 1 1 to augment the force supplied by the pedaling action of the rider. In some embodiments the amount of radial deflection may be proportional or almost proportional to the torque supplied by the rider, or the torque supplied to the hub by the sprocket set which ultimately is driven by the rider. The axle 30, motor armature 28 with electromagnets 24, and PCB 38 with attached optical emitter and sensor 42, 44 are stationary, whereas the drive motor wheel hub 12 with attached permanent magnets 24 and registration disc 52 spin about the axle 30 while the cassette freewheel body 66 (and torque bushing 62) with attached deflection disc 48 also spin about the axle 30 but are angularly displaceable relative to the main body of the wheel hub 12 and the registration disc 52 attached thereto, so that deflection 76 is correlated to the torque difference between pedal input and motor speed. The speed of the motor or the speed of the wheel as driven by the rider doesn't matter, as the percentage of optical reflection by segments 56, 58 sensed over several apertures 50 by the optical sensor 44 always represents true applied input torque.

Unlike the known prior art, which primarily relies on horizontal shaft deflection detected by a resistive bridge strain gauge to detect pedal torque, the present invention uses a mechanically isolated optical deflection reader, formed by the optical emitter and sensor 42, 44, which employs the registration disc 52 viewed through the deflection disc 48 to rotationally cause a deflection 76 that is related to the force on the pedal. Note that while these discs 48, 52 have a superficial similarity to digital rotary encoders, they are not similar in their function or implementation, and produce an analog light output related to pedal torque, and are not necessarily required to transmit any form of rotary encoded timing data.

As outlined above, the rotary torque input from the pedal action is transmitted to the inside of the wheel hub 12 by means of a semi-rigid torsion coupling similar to flexible couplings on shaft drives. This coupling, formed by the torque bushing 62 in conjunction with the torque deflector 60, transmits and transform the input drive torque received from the rider-operated drive mechanism (as applied to the driven sprocket set 68 and cassette freewheel body 66 by pedal action) to an output drive torque applied to the rotatable wheel hub, so that a measurable radial deflection 76 is detectable between the driven sprocket set 68 and the drive motor wheel hub 12.

As shown in Fig. 2, the torque bushing 62 of the coupling is attached to the inside of the deflection disc 48. The torque deflector 60 attaches to the opposite side of the torque bushing 62 and to the inside wall of the freewheel-side plate 16. The deflection disc 48 is a diffuse black optical disc with a multitude of evenly spaced radially segmented apertures 50 as shown. The deflection disc 48 is placed in front of the registration disc 52 with equally alternating diffuse white reflective segments 56 and diffuse black absorptive segments 58. Note that the slit-like aperture 50 could also be round, square, or any other shape that permits accurate and predictable analog illumination output related to pedal torque input. In some embodiments the illumination output may be proportional to the rider's torque input to the wheel hub.

Deflection 76 is measurable when the deflection disc 48 is deflected torque-wise by an angular displacement or rotation about the axle 30 relative to the registration disc 52 in a way that is related to the torque applied. The averaged optical reflection value in percent can be sensed even when the drive motor wheel hub 12 is spinning. The amount of deflection 76 is optically measured by the intensity of light returned to the optical sensor 44 from a ray 46 from the optical emitter 42 bouncing off the reflective segment 56 revealed on the registration disc 52 as seen through the aperture 50 of the deflection disc 48. In a state of zero deflection as shown in Fig. 3d, the black absorptive segment 58 on the registration disc 52 is the only view seen through the aperture 50 of the deflection disc 48, therefore there is virtually no light reflected back to the sensor 44 (note: the actual surface of the deflection disc 48 is completely diffuse black as described above). However, there is a measurable deflection 76, as shown in Fig. 3e, when the deflection disc 48 has rotated an amount that is related to the torque applied so that the view of the optical sensor 44 through the top aperture 50 of the deflection disc 48 is of that displaced portion of a white optically reflective segment 56 on the registration disc 52. By this means, the light intensity measurable by the optical sensor 44, through the aperture 50 of the deflection disc 48 in line with the sensor 44, is directly dependant on the torque applied by the rider.

The reflected light percentage detected by the optical sensor 44 is sent in the form of an analog electrical signal that provides pedal torque input data to the controller 70 from the PCB 38 by means of the power/data cable 36 which passes out of the hub 12 by means of the keyway 74 in the axle 30. As shown in Fig. 5, the electronic power controller 70 determines the amount of power sent by the power source 72 to the motor in the wheel hub 12 based on desired response characteristics and other

programmable limits, and the pedal torque input data. For example, if the rider inputs x amount of torque, and this information is available to the controller 70, and the programmable signal processor is set so that for x amount of pedal torque the motor will be given sufficient electrical current to produce 2x amount of torque in addition to the pedal torque supplied, the total augmented torque output would equal 3x. Many variations to this example are possible, and are only limited by the maximum pedal and motor torque capable of being produced, and the range of pre-programmed response characteristics and settings available to the controller 70.

For example, the torque provided by the motor may be proportional to the torque provided by the rider, the average torque provided by the rider, or it may compensate for unevenness in the torque supplied by the rider such that the total torque is constant over a given duration of time, or varies on a moving average basis. The output of the torque sensor as a function of applied torque may be linear or non-linear, such as logarithmic, exponential, quadratic, square root or dependent on another power factor. The response curve of the sensor can be tailored according to the range where maximum sensitivity in the torque measurement is required. Tailoring of the response curve may be done electronically or mechanically (as described below), or by using a combination of both.

The torque sensor may also be configured to measure the speed of the motor, for example by measuring the number of pulses per unit time, where each pulse interval corresponds to a known angular rotation and/or a known distance moved. The additional torque applied by an electric motor may therefore be a function of the speed of the motor or a function of both the speed and the torque provided by a human or other power source.

Other exemplary embodiments of the torque sensing system 10 will now be described. The non-contact torque sensor elements used in the exemplary embodiment may also be used to sense, record and transmit rotary torque data without the use of a force coupled motor, such as in a non-motorized bike wheel hub, or in free-running wheel hubs in other types of vehicles such as carts or tricycles. Also, the splined end 64 of the torque bushing 62 is but one example of commonly used methods employed to connect to a cassette freewheel body 66, and other methods such as thread-on, bolt mounting, or similar methods leading to the same result may also be provided for in alternate embodiments. As described above, the aperture 50 of the deflection disc 48 may take any shape or configuration that permits consistent and accurate analog reflected illumination that is correlated in a consistent and defined manner to the pedal (or manual drive) torque input. Alternatively, it should be understood that the keyway 74, as seen in Fig. 1 , through which the power/data cable 36 exits the stationary portion of the hub 12 also may symbolize the form of a wireway running axially through the interior of the axle 30. This affords the option of sealing the cable 36 from exposure to the elements by means of a waterproof conduit which may continue to the power source 72.

Exemplary construction materials include cast aluminum for the armature, electromagnet, wheel hub, etc. Commonly used metal compounds as used in the bicycle industry are used for the axle, freewheel, and similar components. The torque bushing may be made of any commonly used bearing material such as brass, and the torque deflector of any material with appropriate elastic properties that allows a predictable deflection within the parameters of the disc aperture deflections.

The registration disc 48 and torque bushing 62 may be combined in a unitary component. For example, the combined torque deflector and registration disc may in the form of a spider as shown in Fig. 6. The torque bushing may be connected to the centre region 82 of the spider, and the hub to the outer region 84. The arms 86, acting as torque deflectors, may undergo deflection as torque is applied to the centre 82 of the spider by a rider, or other power source. The outer region of the spider 84 may transmit rotational drive force to the hub. The range of deformation of the torque deflector should be within the elastic deformation range for the material it is made from. The shape of the torque deflecting arms 86 of the spider may be straight, curved, zig-zag, S-shaped, radial, oblique and they may vary in cross-section from inner end to outer end. The physical configuration of the arms 86 may be such that the angle of deflection is a linear or non-linear function of the applied torque. The length and thickness of the arms 86 may be made differently for greater or lesser deflection for the same amount of torque. Longer, thinner arms will give a greater deflection response. One or more springs may also be used as the torque deflector, and these may be linear or non-linear springs. An example of a spring that may be used is a coil spring.

Other advantages of using the torque sensing system 10 of the present invention over other methods or devices will now be described. Torque sensing by means of a strain gauge requires a means of considerable signal amplification which necessitates additional signal processing and filtering that lead to response delays and other data processing challenges, whereas the opto-mechanical torque sensing system 10 of the present invention provides a strong, consistent and directly relevant analog data output which may communicate pedal torque input without a need for complex electronics, signal processing or amplification techniques. Electronic differential torque data outputs can be used to monitor and interpret pedal torque which in turn can be used to compute and provide desired motor drive signals as well as other relevant parameters such as data logging. Other approaches require that their circuitry must spin with the hub, therefore requiring wireless data transmission and batteries or brushed commutators to connect. The present approach houses the PCB 38 and torque sensor detection circuitry in the stationary part of the wheel hub 12, therefore all signals and power connection can easily be wired by conventional means. This approach increases reliability, accessibility and reduces likelihood of vibration related electrical and alignment failures.

The torque sensing principles and embodiment described above apply to both the static as well as the dynamic mode (i.e. wheel stationary or spinning). In cases where the torque is only desired to be measured on a rotating wheel, a segmented aperture arrangement as described in the exemplary embodiment can be used, and optical detector and associated electronics can be configured, to measure the pulse widths or pulse width ratio created by the absorption and reflectance transitions. From the measured pulse widths and/or pulse width ratio, the torque can be determined. For example, the duration of each pulse may be measured and/or averaged over two or more apertures. In this embodiment, the sensitivity of the measurements can be increased by increasing the number of apertures.

If the registration and aperture discs are aligned such that the amount of light measured is mid-way, or otherwise, between minimum and maximum, then the torque sensor may be configured to measure torques applied to the hub in both forward and reverse directions.

While the description has been made in reference to torque sensing in a brushless motor, the torque sensor may also be used in wheel motors employing other techniques such as brushed motors, AC induction motors or stepper motors. Industrial Applicability

From the foregoing description, it should be ready apparent that the torque sensing system of the present invention can provide non-contact detection of rider torque drive input, for example, to a force coupled brushless motor drive wheel hub used on a bicycle wheel employing a cassette type freewheel, or any similar application such as use with wheelchairs, carts, tricycles, or other human rider powered vehicles. Thus, instead of using strain gauges to detect horizontal shaft deflection to measure pedal force, or similar human input force such as hand-operated crank force, the disclosed torque sensing system employs mechanically isolated optical torque deflection and sensing that allow pedal torque data to be read from inside the motor drive hub and sent to a power controller to govern motor augmentation.

The torque sensing system of the present invention also allows pedal torque detection on freewheel hubs with cassette type sprocket sets used on bicycle rear wheel electrically driven motor hubs. Cassette freewheel hubs are a recent innovation which allow more robust components to be used, and permit a wider range of sprockets to be employed. Also, by enclosing the torque sensing elements inside the wheel hub, they are both protected from the elements. Also there are no compatibility issues between sensors attached to a bike frame, and the use of a different wheel hub or controller configuration in the future. The ability to detect and measure in a

mechanically isolated fashion the rotary torque applied to a stationary or moving drive hub may also be used with drive motors employed on electric wheelchairs, small carts or other powered devices. The ability to detect and measure rotary torque on moving hubs, axles or shafts can also be applied to non-motorized hubs such as in

measurement hubs for cycling. As an example, elite athletes may want to record and analyse the pattern of torque they produce during training exercises, which may be carried out on a bicycle or a cycling machine in a gym.

The torque sensor may also be used in electric hybrid vehicles that are driven by a combination of a gasoline powered engine and an electric motor, or in vehicles driven by a combination of a diesel powered engine and an electric motor.

The foregoing description of the preferred apparatus and method of installation should be considered as illustrative only, and not limiting. Other forming techniques and other materials and components may be employed towards similar ends. Various changes and modifications will occur to those skilled in the art, without departing from the true scope of the invention as defined in the present disclosure.

What is claimed is:

Claims

1. A wheel hub assembly having a wheel hub mounted for undergoing rotation in a given direction about an axle and a drive mechanism mounted for undergoing rotation in said given direction in response to an input drive torque applied to said drive mechanism, wherein said wheel hub assembly is characterized by:

a coupling mounted to said drive mechanism for undergoing rotation therewith and adapted to couple said drive mechanism to said wheel hub so as to undergo angular deflection relative to said wheel hub about said axle and concurrently transform said input drive torque received from said drive mechanism to an output drive torque applied to said wheel hub; and

an opto-mechanical torque sensing system adapted to produce a reflected ray of light correlated to the angular deflection of said coupling relative to said wheel hub, measure the amount of reflected light, and generate an output correlated to said input drive torque applied to said drive mechanism.

2. The wheel hub assembly of claim 1 further characterized by said output being a signal in one of analog or pulse form.

3. The wheel hub assembly of claim 1 further characterized by said optomechanical torque sensing system including an optical deflection reader adapted to emit a reflectable ray of light, detect the reflected light, and measure the intensity of the reflected light.

4. The wheel hub assembly of claim 3 further characterized by said optical deflection reader including an optical emitter adapted to emit the reflectable ray of light.

5. The wheel hub assembly of claim 4 further characterized by said optical deflection reader including an optical sensor adapted to detect the reflected light and measure the intensity of the reflected light.

6. The wheel hub assembly of claim 3 further characterized by said torque sensing system including a registration disc mounted to said hub for undergoing rotation therewith, said registration disc having alternating light absorptive and light reflective segments.

7. The wheel hub assembly of claim 3 further characterized by said torque sensing system including a deflection disc mounted to said coupling for undergoing said angular deflection therewith relative to said registration disc and being spaced from said registration disc and said optical deflection reader for non-contacting interaction therewith, said deflection disc having at least one aperture in alignment with at least a portion of said segments of said registration disc passing said resectable ray of light and said reflected light to and from said portion of said segments of said registration disc as viewed through said at least one aperture by said optical deflection reader.

8. A rider-propelled vehicle having an axle, a wheel hub mounted for undergoing rotation about said axle in a given direction, a drive motor housed inside said wheel hub and coupled between said wheel hub and said axle and operable to cause rotation of said wheel hub about said axle, and a rider-operated drive mechanism mounted for undergoing rotation about said axle in said given direction in response to an input drive torque applied to said drive mechanism, wherein said rider-propelled vehicle is characterized by:

a coupling mounted to said drive mechanism for undergoing rotation therewith, said coupling disposed inside said wheel hub and adapted to couple said drive mechanism to said wheel hub so as to undergo angular deflection relative to said wheel hub about said axle and concurrently transform said input drive torque received from said drive mechanism to an output drive torque applied to said wheel hub; and

an opto-mechanical torque sensing system adapted to produce inside said wheel hub a reflected ray of light correlated to the angular deflection of said coupling relative to said wheel hub, measure inside said wheel hub the amount of reflected light, generate inside said wheel hub an output correlated to said input drive torque applied to said drive mechanism, and transmit said output from inside to outside of said wheel hub.

9. The rider-propelled vehicle of claim 8 further characterized by said optomechanical torque sensing system including an optical deflection reader disposed inside said wheel hub and adapted to emit a reflectable ray of light, detect the reflected light, and measure the intensity of the reflected light.

10. The rider-propelled vehicle of claim 9 further characterized by said optical deflection reader including an optical emitter disposed inside said wheel hub and adapted to emit the reflectable ray of light.

1 1 . The rider-propelled vehicle of claim 9 further characterized by said optical deflection reader including an optical sensor disposed inside said wheel hub and adapted to detect the reflected light and measure the intensity of the reflected light.

12. The rider-propelled vehicle of claim 9 further characterized by said torque sensing system including a registration disc mounted inside said wheel hub to said wheel hub for undergoing rotation therewith, said registration disc having alternating light absorptive and light reflective segments.

13. The rider-propelled vehicle of claim 12 further characterized by said torque sensing system including a deflection disc mounted inside said wheel hub to said coupling for undergoing said angular deflection therewith relative to said registration disc and being spaced from said registration disc and said optical deflection reader for non-contacting interaction therewith, said deflection disc having at least one aperture in alignment with at least a portion of said segments of said registration disc for passing said reflectable ray of light and said reflected light to and from said portion of said segments of said registration disc as viewed through said at least one aperture by said optical deflection reader.

14. The rider-propelled vehicle of claim 8 further characterized by said torque sensing system including a power supply adapted to provide power to operate said drive motor and a controller adapted to receive the output from said opto-mechanical torque sensing system and provide an output to regulate said power supply.

15. A rider-propelled vehicle having a wheel hub mounted for undergoing rotation in a given direction about an axle and a rider-operated drive mechanism mounted for undergoing rotation in said given direction in response to an input drive torque applied to said drive mechanism, wherein said rider-propelled vehicle is characterized by: