NL2008846C2

NL2008846C2 - Electric power generator and its use in a running light.

Info

Publication number: NL2008846C2
Application number: NL2008846A
Authority: NL
Inventors: Rena E Catrien Walraven
Original assignee: Asics Europ B V
Priority date: 2012-05-21
Filing date: 2012-05-21
Publication date: 2013-11-25

Description

Electric power generator and its use in a running light

The present invention relates to electric power generators and in particular to electric power generators that generate electric current by movement. The invention further 5 relates to a running light, provided with the electric power generator.

BACKGROUND OF THE INVENTION

In many instances it is desirable to improve the visibility of a moving object. The 10 visibility of bicycle riders or runners to others in dark conditions for instance may be lifesaving. Both reflectors and active lights have been proposed to make such objects more visible. While reflectors are often low weight and cheap, active lights may help a rider or runner to see by illuminating the way forward.

15 Especially for runners, the use of active lights is not totally satisfactory. The lights are either too heavy or produce not enough light to be of any practical use. Also, active lights may actually give too much light, thereby blinding other road users. Another major disadvantage of current lights is that it depends on power supply in the form of battery’s. If the battery turns low or empty there is no light.

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It is an object of the present invention therefore to provide an efficient and light weight electric power generator that can generate electric current by a movement, such as typically made by a runner. It is a further object of the invention to provide a light weight running light wherein some of the disadvantages of the known running light are 25 at least partly overcome.

SUMMARY OF THE INVENTION

The present invention thereto provides an electric power generator that generates electric current by movement, the generator comprising a movable magnet and a fixed 30 magnet that repel each other (having facing surfaces with the same polarization) within the confined space of a container that allows the movable magnet to move with a substantially bi-directional linear motion within its confined space, the generator further comprising a coil surrounding the confined space and substantially extending across the movement range of the moving magnet, in which coil electric current is produced as a 2 result of the movement of the moving magnet. The electric power generator of the invention provides for efficient electric power generation from mechanical forces acting on the moving magnet and incited by a movement, for instance the movements made by a runner. Since the electric power generator according to the invention is powered by 5 motion, the light is guaranteed when it is used in a running light.

In a preferred embodiment of the invention, an electric power generator is provided that comprises one coil only, and more preferably one fixed magnet only. Such a generator combines low weight with sufficient power generation. It has been established that the 10 movement of a runner, especially its arm movements, provides a level of mechanical power that allows sufficient power to be generated by the present embodiment to produce enough light when applied to a running light, as described further below.

A preferred embodiment of the invention provides an electric power generator, wherein 15 the movable magnet comprises a plurality of mutually connected magnets.

Particularly useful results have been obtained by an embodiment of the electric power generator, wherein the mutually connected magnets are connected to a soft magnetic pole piece between the magnets. More preferred is an embodiment of the electric power 20 generator, wherein the magnets are connected to each or optionally to the soft magnetic pole piece by adhesive bonding.

In case weight is of lesser concern, an embodiment of the invention provides an electric generator, comprising a plurality of movable magnets. The magnets are not connected 25 to each other in this embodiment and may move substantially freely within the container, albeit limited in motion by the opposed magnetic field generated by the fixed magnet.

The movable and/or fixed magnet in the electric power generator in accordance with the 30 invention may be chosen within a wide range of magnets available. Preferably however, an electric power generator according to one embodiment of the invention comprises movable and/or fixed magnet(s) chosen from a rare earth magnet or a ceramic disc magnet, or a combination thereof.

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In order not to inhibit the movement of the movable magnet within the container, one embodiment of the electric power generator is proposed, wherein the container wall comprises venting openings through which air can escape. The venting openings preferably are provided in the top cover of the container. In order to reduce the sound 5 emitted by the moving magnet in the container, the container, and in particular the top cover thereof, is preferably provided with a sound damping element, such as a rubber or foam damping piece. The sound damping element is preferably provided at the inside of the container.

10 The electrical energy produced by the generator is of an irregular nature, since the movements experienced by the generator will generally not be continuous. In a preferred embodiment therefore, the generator is provided with a capacitor to store the energy generated.

15 Another embodiment of the invention provides an electric power generator, wherein the container has an inside wall and the moving magnet is sized to provide a substantial clearance between its outer wall and the containers inside wall. This allows movement of the moving magnet, even after prolonged times when the inner confined space may have accumulated foreign matter, such as dirt. This is especially of concern for runners.

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The container of the electric power generator in accordance with the invention may be manufactured from any material that however may not be magnetisable. When the case/container of the electric power generator is manufactured of a magnetized material, the case will attract the magnets, keeping the magnets from moving through the coil.

25 Consequently no energy will be generated. The case or container therefore should not be made of magnetized material. The material of the case/container where the magnets glide though is preferably smooth and creates a minimum resistance only. Suitable materials include metals such as aluminium, steel, iron, brass, copper and the like, aluminium being preferred for its low weight. In another preferred embodiment of the 30 invention, the container is manufactured from a light weight polymer, preferably a polyolefin.

The electric power generator in accordance with the invention is particularly useful in a running light, due to its optimum combination of low weight and electric power level 4 produced. The invention therefore also relates to a running light comprising a generator according to the invention and one or more LED’s electrically connected thereto.

It is preferred to provide a running light, wherein at least two LED’s are electrically 5 connected in anti-parallel. Because in this embodiment the LED’s are anti-parallel, the running light has an increased efficiency, which also means that the running light can be made as light-weighted as possible.

To optimally make use of the typical movements of a runner and not to hinder these 10 movements, an embodiment of the running light, comprising a housing for the generator and the LED or LED’s, the housing having attachment means for attachment to a bracelet, belt or the like to be used by a moving creature, is particularly preferred. The attachment means are preferably designed for attachment to the upper body of a person, and most preferably to the wrist of a person.

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An embodiment of the running light according to the invention, wherein the housing is adapted to house an elongated electric power generator in accordance with the invention with its axis of elongation substantially parallel to the direction of gravity has proven to be particularly efficient.

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BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to the following figures without however being limited thereto. In the figures: figure 1 schematically shows a cross-section of an embodiment of the electric power 25 generator in accordance with the invention; figure 2 schematically shows a cross-section of another embodiment of the electric power generator in accordance with the invention; and figure 3 shows an exploded perspective view of an embodiment of a running light and a housing having attachment means for attachment to a bracelet.

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With reference to figure 1, an electric power generator in accordance with an embodiment of the invention comprises a container in the form of a polypropylene tube 1, having a wall thickness of 0.8 mm, an outside diameter of 17 mm and a length of 55 mm. Other materials besides polypropylene may be used comprising acrylic polymers, 5 styrene polymers, glass, fluorine polymers, but also metals such as aluminium. The material is preferably non-ferrous.

Tube 1 contains a movable magnet 2 which in the embodiment shown is a disc magnet 5 comprised of Nickel and Copper with a diameter of 15 mm and a thickness of 8 mm. A coil 3 is wrapped around the tube 1 at the height of the midplane thereof in its longitudinal direction 4 or slightly above it. Coil 3 preferably is applied in the upper part of the tube 1. Coil 3 has 1000 turns and made of copper wire with a diameter of 80 micrometers. Coil 3 has a length in the longitudinal direction 4 of the tube 1 of about 10 10 mm, which is about equal to the thickness of movable magnet 2, although this needs not be so. The coil 3 is attached to the outer wall of the container 1 by any means, such as by an adhesive or cement, or by mechanical means. The tube 1 is apart from the movable magnet 2 provided with a fixed magnet 5 close to the bottom part of the tube 1. Movable magnet 2 and fixed magnet 5 repel each other as they have facing surfaces 15 with the same polarization. When the tube 1 is subject to a movement, preferably a movement substantially in the longitudinal direction 4 of the tube 1, movable magnet 2 is allowed to move with a substantially bi-directional linear motion in the direction 4 within the confined space of the tube 1. Fixed magnet 5 in the embodiment shown is a ceramic disc magnet with a diameter of 10 mm and a thickness of 1 mm. Fixed magnet 20 5 is in polar opposition to movable magnet 2 so as to suspend magnet 2 by repulsive magnetic force, and counteract the downward movement of magnet 2 under gravity when the tube 1 is in a substantially vertical position. In the figures the symbol ‘N’ is used for a North polarization, whereas the symbol ‘S’ denotes a South polarization. The fixed magnet 5 may be attached to the tube 1 by any means, such as by adhesive 25 bonding or by clamping it in place. An up and down motion of the tube 1, such as caused by the movement of a runner, causes an up and down movement of the movable magnet 2 within the magnetic filed of coil 3, thereby generating a current within the coil 3.

30 To be effective, magnet 2 should be able to move substantially freely in the confined space of tube 1 and have a relatively high magnetic strength causing a relatively high amount of magnetic flux lines through the coil 3. Suitable magnets include Nickel and Copper coating whereby N42 magnets are particularly preferred.

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In order to promote unhindered motion of the moving magnet 2 within the inner confines of the tube 1, the moving magnet 2 is sized to provide a substantial clearance between its outer wall and the tubes inside wall. Preferred clearances range from 0,2 to 1 mm, more preferably from 0,3 to 0,8 mm and most preferably from 0,4 to 0,6 mm.

5 The shape of the movable magnet 2 moreover preferably is such that the thickness thereof (the dimension in the longitudinal direction 4 of the tube 1) is larger than its diameter. The ratio of thickness to diameter preferably is larger than 1, more preferably larger than 1.2 and most preferably larger than 1,5.

10 Shaking of the tube 1 in a direction substantially parallel tot the longitudinal direction 4 of the tube 1 caused a peak to peak voltage of about 2 volts. The electric resistance of the coil 3 was 400 ohms, such that the electric power generator of this embodiment delivered about 4 mW of electrical power.

15 Another embodiment of the electric power generator as shown in figure 2 comprises a tube 1 wherein a movable magnet 2 is contained. The movable magnet 2 consists of two mutually connected magnets (20, 21). The magnets (20, 21) are each connected to a soft magnetic pole piece 22 in between by adhesive bonding. The magnetic pole piece is made of copper and has a thickness of 2 mm and about the same diameter as magnets 20 (20, 21). The moving magnet 2 is in this embodiment has increased thickness which, together with a clearance between its outer wall and the tubes inner wall of preferably from 0,2 to 1 mm, more preferably from 0,3 to 0,8 mm and most preferably from 0,4 to 0,6 mm, yields a substantially unhindered movement of the magnet 12 within the tube 1. The electric power generated is also higher for one type of movement. Shaking of the 25 tube 1 in a direction substantially parallel tot the longitudinal direction 4 of the tube 1 caused a peak to peak voltage of about 2 volts. The electric resistance of the coil 3 was 400 ohms, such that the electric power generator of this embodiment delivered about 4 mW of electrical power.

30 In order to be able to design small units of generator, the clearance between movable magnet 2 and the wall of tube 1 should be as small as possible. However, an embodiment wherein the end parts of the tube are provided with openings 6 or notches permits air to circulate more freely, especially in the embodiment of figure 2, which uses a movable magnet with a relatively large thickness to diameter ratio. Holes, 7 openings or notches may also be provided in the circumferential wall of the tube 1 to vent the air. Without the notches or openings in the wall(s) of tube 1, the motion of the moving magnet 2 may become damped since it would have to compress closed in air. This effect may also be counteracted by the preferred ranges for the clearance between 5 the outer wall of magnet 2 and the inner wall of the container 1, as indicated above. The magnet 2 may also be provided with one or more holes, letting air freely pass through it. However, such a solution may affect electric power generation.

The electric power generator is preferably used in a running light, an embodiment of 10 which is shown in figure in exploded view. To optimally make use of the typical movements of a runner and not to hinder these movements, the embodiment shown comprises a housing 10 for a generator of which the container 1 is visible only. The housing has attachment means (not shown) for attachment to attachment means in the form of a clamping unit 11 provided on a bracelet 12, which may be applied on the 15 wrist or ankle of a runner for instance. The housing 10 comprises two shell-shaped interlockable parts (10a, 10b), a sealing top part 10c with an opening for one or more light emitting diodes (LED) and a translucent top cover lOd. The configuration of belt 12 and tube 1 is such that the elongated tube shaped electric power generator extends with its axis of elongation substantially parallel to the direction of gravity 7.

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As shown in figures 1 and 3, the coil 3 is electrically connected to a LED 9 or to more LED’s (9a, 9b) by electrical wires 8. In the embodiment shown, two LEDS (9a, 9b) are shown in anti-parallel. In a positive alternation of the alternating current produced by the electric power generator, LED 9a will conduct the electric current and LED 9b will 25 obstruct the electric current. In a negative alternation LED 9b will conduct and LED 9a will obstruct. Due to the frequency of alternation, this effect will not or hardly be visible.

The electrical circuit may if desired be supplemented with other components such as an 30 energy storage capacitor and/or a rechargeable battery unit. The movements of a runner for instance have appeared to be such that a supply of power to an energy storage device may be feasible.

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The above description of some preferred embodiments of the present invention are not intended to limit the scope of the invention, and many variations of the present invention can be envisaged by the skilled person within the scope of the claims attached hereto.

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Claims

An electric power generator that generates electric current through a movement thereof, the generator comprising a movable magnet and a fixed magnet that repel each other within the enclosed space of a holder, which holder permits movement of the movable magnet with a substantially bi-directional linear movement in the enclosed space, the generator further comprising a coil surrounding the enclosed space and extending substantially over the movement range of the moving magnet, in which coil 10 electric current is generated as a result of the movement of the moving magnet magnet.

An electric power generator according to claim 1, comprising a single coil. 15

Electric power generator according to claim 1 or 2, comprising a single fixed magnet.

4. Electric power generator according to any one of the preceding claims, wherein the movable magnet comprises a plurality of mutually connected magnets.

The electric power generator according to claim 4, wherein the interconnected magnets are connected to a soft magnetic pole piece between the magnets. 25

Electric power generator according to claim 4 or 5, wherein the magnets are connected to each other, or optionally to the soft magnetic pole piece, by means of gluing.

7. Electric power generator as claimed in any of the foregoing claims, comprising a multiple number of movable magnets.

An electric power generator according to any one of the preceding claims, wherein the movable and / or fixed magnet is selected from a rare earth metal magnet, or a ceramic disc magnet, or a combination thereof.

9. Electric power generator as claimed in any of the foregoing claims, wherein the holder wall comprises vent openings through which air can escape.

10. Electric power generator according to any one of the preceding claims, wherein the holder has an inner wall and the size of the moving magnet is such that there is a substantial clearance between its outer wall and the inner wall of the holder.

Electric power generator as claimed in any of the foregoing claims, wherein the holder is made of a lightweight plastic, preferably a polyolefin. 15

A running lamp comprising an exciter according to any one of the preceding claims and one or more electrically connected LEDs.

13. Running lamp according to claim 12, wherein at least two LEDs are electrically connected in anti-parallel circuit.

14. Running lamp according to claim 12 or 13, comprising a housing for the generator and the LED or LEDs, wherein the housing has mounting means for mounting on a bracelet, belt or the like, and can be used by a moving creature.

15. Running lamp according to any one of claims 12 to 14, wherein the housing is adapted to contain an elongated electric power generator in accordance with one of claims 1 to 11 with its longitudinal axis substantially parallel to the direction of gravity.