WO2014045043A2

WO2014045043A2 - Wheel energy scavenging

Info

Publication number: WO2014045043A2
Application number: PCT/GB2013/052461
Authority: WO
Inventors: Gregory Hall
Original assignee: Fusion Innovations Ltd
Priority date: 2012-09-20
Filing date: 2013-09-19
Publication date: 2014-03-27
Also published as: GB201216874D0; WO2014045043A3

Abstract

A device (20) is attached to a vehicle wheel (10) at a location radially spaced from the axis of rotation (A) of the wheel. The device comprises a housing (21) attached to the wheel, a mass (30) configured to move relative to the housing in response to combined rotational and translational movement of the wheel and a transducer (91) fixed to the housing and responsive to the motion of the mass.

Description

WHEEL ENERGY SCAVENGING

TECHNICAL FIELD

The present invention relates to wheel energy scavenging or harvesting, particularly for vehicle wheels.

BACKGROUND ART US 2008-0129153 discloses an inertial energy scavenger that includes at least one piezoelectric element held by a housing, a proof mass that is movable within the housing in a direction parallel to the piezoelectric element, and a mechanical assembly disposed between the proof mass and the piezoelectric element. The mechanical assembly transfers work from the proof mass to the piezoelectric element, where the work from the proof mass is a first force along a first distance and the work to the piezoelectric element is a second force along a second distance. The first distance is greater than the second distance and the first force is smaller than the second force. Force amplification is determined by the geometry of the mechanical transfer assembly and can range anywhere from just above 1 to at least 10, where some embodiments include a bi-lever configuration, a tube- shaped configuration and a reverse actuation configuration.

US4504761 discloses a piezoelectric array mounted on one or more tyres of a motor vehicle. As the vehicle drives down the road, the tyre is flexed during each revolution to distort the piezoelectric elements and generate electricity. An electric circuit delivers the energy to the electrical system of the vehicle. US2010052886 describes a procedure for controlling the transmission operation of a tyre pressure monitoring device arranged in a pneumatic tyre of a vehicle, whereby data telegrams are transmitted in a normal mode of operation in first time intervals, and there is a changeover from the normal mode of operation to a pressure drop mode, if an inspection of the pressure signals indicates a drop in the pressure of a drop speed exceeding a pre-defined threshold value, and data telegrams are transmitted in the pressure drop mode in second time intervals, which are shorter than the first time intervals, and the tyre pressure monitoring devices are put into a travel starting mode at the beginning of the travel by activation a roll sensor. Data telegrams are transmitted in the travel starting mode in shorter third time intervals as compared to the normal mode of operation.

DISCLOSURE OF INVENTION

Aspects of the invention are defined in the attached independent claims, with embodiments being defined in the dependent claims and the following description.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described by way of example with reference to the following drawings, of which:

Figure 1 shows a wheel and device according to the present invention;

Figure 2 shows a first embodiment of the device;

Figure 3 illustrates the voltage output from the device of figure 2;

Figure 4 is a schematic view of a second embodiment of the device;

Figure 5 is a perspective view of the arrangement of figure 4 incorporated into a simple dual valve system; Figures 6A and 6B are detail sectional views of the valves K and I of figure 5; Figures 7A and 7B are detail sectional views of the air pump cylinders of figure 5;

Figure 8 is a perspective view of a third embodiment of the invention;

Figure 9 is a perspective view of a fourth embodiment of the invention;

MODES FOR CARRYING OUT THE INVENTION

Figure 1 shows a wheel 10 rotatable about an axis A while rolling, moving in translation, in a direction B along a surface 11 such as road. A device 20 is spaced radially from the axis A and, as shown, is attached to the wheel near the periphery thereof.

As shown in figure 2, device 20 comprises a housing, indicated by dashed lines 21, which is in turn attached to the wheel. Inside the housing is a mass 30 fixed to the first end 42 of an arm 40 attached to the housing 21 by a pivot 50, the centre of the mass being radially offset from the pivot by a distance LI . As indicated by arrow 41, arm 40 is rotatable about the axis of the pivot 50 against the action of spring 60 which is attached at a first end 62 to the housing 21 and at a second end 64 to a second end 44 of the arm, on the opposite side of the pivot to the first end 42 of the arm and at a radial distance L2 from the pivot. As shown, the axis of the pivot 50 is aligned parallel with the axis A of the wheel and two springs 60, 70 are attached in opposition to the second end 44 of the arm. However, the system may also be mounted out-of-plane within the wheel such that the centrifugal component of acceleration has no moment around the axis of rotation of the pendulum.

As shown, mass 30 comprises a coil 80, akin to that found in the arm of a hard disk drive. A magnet 90 is attached to the housing 21 adjacent the coil 80, thereby forming a transducer 91 that generates a voltage that is proportional to the relative velocity of the arm 40 to the housing 21. An experimental trace of this voltage is shown in figure 3 for a wheel of 0.34 m outer radius and a device installed at a radius of 0.24 m.

The energy generated can, for example, be used to power wireless systems which may include systems such as Bluetooth or ZigBee or others. The device when fitted to a wireless system can be used with an electronically activated pressure regulation valve to be able to adjust the tyre pressures from a remote location away from the wheel such as the vehicle's occupant space.

Figure 4 is a schematic view of a second embodiment of the device in which the lumped mass 30 is fixed in the plane of the direction of acceleration DA and moves against springs 60, 64. The mass is formed with cam 200 surfaces that engage and actuate (via respective rollers) air pump cylinders 210. The cam allows the pump to regulate the amount of air being pumped against the force available to pump it. The shape of the lumped mass is designed with the cam being such that it allows the stroke of the pump to extend related to the distance the lumped mass is able to travel against the sprung extremities. The greater the distance the greater the cam allows the stroke to extend and creates the greater volume of air.

Mass 30 additionally comprises a magnet, thereby generating electrical energy in induction coils fitted on the front and rear panels 220, 230. The device can also be used in a symmetrically distributed layout and used around the circumference of the driving object.

As shown, the control of the motion of the lumped mass is by means of a single direction sliding mechanism meaning it can only move in the axis of the springs. However, a cam type mechanism where the lumped mass is able to move to a greater range of cycloid motion according to the combined vector force below, is also possible. In such a motion the inductance coils could also be arranged such that they optimised this motion.

Figure 5 is a perspective view of the arrangement of figure 4 incorporated into a simple dual valve system where the valve tube contains both a one way conventional valve for traditional pumping and a secondary pressure valve with an adjustable spring stiffness valve for allowing ambient air in to the device. Indicated at A is the lumped mass (preferably magnetic material), at B an air pump, at C a compression spring, at D the air exhaust, at E a locking collar for pressure set, at F an air channel for inlet air from valve I, at G circuitry for WIFI and electrical energy storage, at H an inductance loop, at I the primary inlet valve for pump, at J the main valve casing containing valves I and K and at K the primary tyre chamber valve.

More details of valves K and I is shown in figures 6A and 6B. Valve K is a conventional sprung one way valve akin to that used in traditional systems today and vented to the tyre chamber. This valve operates the pressure of the tyre and ensures air does not exit the tyre through the valve.

Figure 6A is a representation of an inlet valve mechanism that uses a pressure (A) and spring device (B) to control the valve (F). The mechanism is calibrated by clamping (D) onto (C) once the main pressure is set.

Valve I contains a dual pressure and sprung system utilising a setting mechanism that calibrates the inlet valve to the pressure set at the point of activation. As illustrated in figure 6B, when the tyre pressure of force (A) is set it compresses spring (B). The inner sliding collar moves laterally according to the distance the spring is compressed by the air pressure (A). At this point the operator can set the equilibrium position at (C) by using an outer collar to clamp onto the inner collar (D) by screw compression or sliding camber compression (E) and thus the valve's neutral position is set at this point. A reduction in pressure (A) allows the spring (B) to extend and thus slide the inner collar (C) inwards. As the inner collar is clamped to the outer (D) this also moves and acts to open Valve (E) and thus allow air to enter the valve towards the main units inlet valve of the pump.

Fig 6B shows the two valves operating independently in two different segregated chambers. The main purpose for segregation in this particular design is to enable established technologies to be used in primary valve (A) whilst using a new device in (B) being segregated and not affecting the safety aspects of a traditional valve design.

The dual valve design above could be incorporated into a singular design where the valve unit works to operate both the function of inflating the tyre from an outside pressurised air supply and also to allow ambient air to enter the internal air pump when required by the regulation described above.

The simple valve unit described above can replace a typical traditional vehicle tyre valve such as that fitted to the majority of vehicle wheels to date and can be fitted in the same manner as a traditional valve. The unit can be used to both maintain a tyre pressure through a simple second air valve incorporated into the air tube where a spring and screw device can be used to provide a counteracting spring stiffness K to the air pressure P within the tyre where upon being adjusted to reach an equilibrium with the pressure set inside the tyre. If the pressure within the tyre becomes less than the force K then ambient air will be allowed to enter into the device for it to be pumped to return the pressure P to equilibrium with spring stiffness K and thus replacing lost air. The second valve is only connected to the devices pumping chambers which obviously are at a negative pressure on the upward stroke when the inlet is operated and then the inlet is closed and the outlet activated upon the downward pressurised stroke.

This unit if used on a wheel assembly such as one fitted to a wheel valve can be used to not only regulate the tyre pressure but to feedback information to the vehicle and to also receive information from the vehicle to control systems within the tyre such as tyre pressures or other tyre related systems requiring powered control.

Detail of the air pump cylinders is shown in figures 7A and 7B. The roller at the top converts the lateral motion of the lumped mass to a vertical motion whilst the inlet and outlet valves control the airflow. The spring provides the force for the upward stroke of the pump (as indicated by the arrow in figure 7A) and the cam provides the force for the downward stroke (as indicated by the arrow in figure 7B).

The inlet valve 700 is connected to ambient and the outlet valve 710 is connected to the pressured chamber. The inlet valve is connected to a primary inlet valve that only allows air to enter from the ambient supply through a regulated pressure valve. This ensures that the air pump will only be able to pump air should the pressure within the main tyre chamber fall below the pressure that was set upon the first main inflation.

Figure 8 is a perspective view of a third embodiment of the device employing full rotation of the mass 30 around its local pivot axis 50 rather than a constrained motion of the mass against a spring as in the embodiment of figure 2. The lumped mass is free to swing around its own pivot point towards the edge of the wheel. This motion can be found in many planes of rotation such as that of the rotation of the main wheel or even within the plane of a rotation of a point on the circumference of the wheel tangent to the wheel circumference.

One of the main problems of the unconstrained motion is that it cannot optimise its position to optimise the forces acted upon it. However, by appropriate use of sensors and an electrical control unit, the induction resistance can be varied to enable the lumped mass to be in a more optimised position during the rolling motion to best capture the accelerations and decelerations experienced by the mass under rolling conditions. Specifically, an electrical induction circuit may be provided around the lumped mass with the lumped mass as a rotor and the loop as the stator and a control unit to change the induction experienced to increase or decrease the resistance felt by the lumped mass in such a manner as to control its motion.

A pump piston is incorporated into the rotational arm of the rotating mass and rolls around an outer profile of the housing 21. If the housing is not concentric to the path of rotation of the arm, then the casing can effectively become a cam if the arm is sprung so that it can extend and compress a piston and that at one part of the casing the radius is small enough to fully compress the stroke then another part of the casing in the rotation can be larger than the stroke and no contact will be made. The extension and thus air intake will be relative to the centripetal force pulling the piston's spring.

Figure 9 illustrates an alternative pendulum design in which the lumped mass 30 is arranged so as to be closer to the wheel perimeter, in particular towards the tyre's inner surface, where the pendulum would operate or where the cam of a rotating example would best be placed to ensure the compression of the piston utilises the best location and where the centripetal force is largest. The hinged pendulum 30 can also be made of a magnetic material and an induction coil can also be built around this to generate electricity.

Claims

1. Device for attachment to a vehicle wheel at a location radially spaced from the axis of rotation of the wheel; the device comprising:

a housing configured for attachment to a wheel;

a mass configured to move relative to the housing in response to combined rotational and translational movement of the wheel;

a transducer fixed to the housing and responsive to the motion of the mass.

2. Device according to claim 1, wherein the transducer is a pump responsive to the motion of the mass to generate an air flow.

3. Device according to claim 1 or claim 2, wherein the transducer is configured to generate electricity in response to the motion of the mass.

4. Device according to any preceding claim wherein the mass is configured to move in translation relative to the housing.

5. Device according to claim 4, wherein the mass is constrained against movement along more than one axis.

6. Device according to any one of claims 1 to 3, wherein the mass is configured to move in rotation relative to the housing.

7. Device according to claim 6, wherein the centre of the mass is offset from the axis of rotation relative to the housing.

8. Device according to claim 6 or claim 7, wherein the mass is configured to rotate relative to the housing about an axis parallel to the axis of rotation of the wheel.

9. Device according to any one of claims 6 to 8 and configured to limit the rotation of the mass.

10. Device according to any preceding claim, wherein the mass is subject to a biasing force, particularly a spring force.

11. Device according to any preceding claim, wherein the mass comprises a cam surface configured to actuate a pump.

12. Device according to any preceding claim, wherein the mass comprises a magnet and the housing contains an induction coil.

13. Device according to claim 12 and comprising a control unit connected to the induction coil and configured to control the motion of the mass.

14. Wheel comprising a pneumatic tyre and a device according to any preceding claim when dependent on claim 2, the device being configured to pump air into the tyre.

15. Tyre valve comprising a device according to claim 2, the device being configured to pump air into the tyre.