GB2254203A - Dynamo and battery system for a bicycle - Google Patents

Abstract

The system has a relay 5 responding to an output of a.c. dynamo 2 being below a threshold to connect a rechargeable battery 14, 18 to a lamp 3. When the dynamo output is above the threshold, the lamp 3 is energised with a.c. from the dynamo 2, the battery 14, 18 is isolated from both the supply and ground return ends of the lamp 3, and the dynamo 2 recharges the battery via a bridge rectifier 21, a resistor 16 and a diode 17. A key switch (31), (Figure 2), may be provided having a locked state in which supply terminal 12 is disconnected from lamp 3 and flashing direction indicator lights (40), and is connected to a trembler alarm (35) and sounder (36). The unlocked state of the switch allows the lights to be operated and the sounder (36) to be used as a horn. <IMAGE>

Description

POWER SWITCHING MODULE The present invention relates to a power switching module for switching between an a.c. circuit and a d.c. circuit for supplying electrical power to a load, and more particularly to such a module for use in a lighting system for a bicycle.

It has long been known to power the lighting system of a bicycle by means of a dynamo driven by rotation of a wheel.

However, when the bicycle stops, eg at a junction, the lights are extinguished.

A known solution is to provide a rechargeable battery pack which is recharged by the dynamo when the dynamo driving speed is above a threshold value, and which supplies power to the lighting system when the dynamo driving speed falls below that threshold value. Whilst the dynamo can produce a.c. or d.c.

with suitable circuitry, power for the lighting system above the threshold and the battery pack can produce d.c. power below the threshold, it is technically simpler and hence preferred to supply a.c. from the dynamo to the lights since this is the standard unit fitted to most bikes because no additional electrical circuitry is required. Moreover, since it is convenient to retro-fit the above to standard units already in place on bicycles, it is preferred to power the lights with a.c. from the dynamo.

A known example using a.c. to power the lights is given in GB A-2126438 and GB-A-2161040 wherein when the dynamo output drops below a threshold value, a circuit is formed between the lights and the battery via a wire and the electrically conducting bike frame so as to supply d.c. to the lights. When the dynamo output exceeds the threshold value, a switch firstly connects the dynamo into a circuit via a wire and the electrically conducting bicycle frame so as to supply a.c. to the lights-, and secondly connects the dynamo via a rectifier to charge the battery. However, when this is done in relation to the rechargeable battery system described above, it is found that the system does not work.It is believed this is because the rechargeable battery is still connected to the bicycle frame when the dynamo circuit is operating the lights, and so the d.c. potential influences the operation of the a.c. circuit and the associated electrical components.

Modern technology has enabled manufacturers to produce a dynamo which performs within its designated parameters ie it will produce six volts a.c. almost instantaneously of the wheel turning and remain within a few volts of it at high speed.

Prior to this, hub dynamos, for instance, could have outputs which varied from three volts to twenty volts depending on the rotational speed and load.

Although voltage can be 'clipped' using readily available components, it is the power a dynamo produces which is important. Modern bicycle dynamos usually produce six volts at three watts.

With such a small amount of power available it is most desirable that the charging system be designed such that it does not impair the brightness of the lights.

It is an-object of the present invention to obtain in a simple and convenient way, and taking into consideration the available power, the advantages of powering the lights no matter what the dynamo speed is, whilst overcoming the disadvantages associated with the prior art.

It is another object of the invention to provide a module which may be readily attached to any bicycle already fitted with a dynamo with minimal alteration to the wiring.

According to the present invention, there is provided a power switching module for a pedal driven vehicle having a first conductive route between an a.c. dynamo and a load and a second conductive route between the a.c. dynamo and the load to complete a circuit, the module comprising:battery terminals for receiving battery means, and switching means connected in use to break into said first conductive route; the switching means having a first state connecting one battery terminal to the load via the first conductive route and the other battery terminal to the load via the second conductive route, and a second state when the dynamo output exceeds a threshold value wherein the dynamo is connected to the load via the first conductive route and isolating the battery terminals from the first and second conductive. routes.

By isolating the battery terminals from the first and second conductive routes in the second state, the present invention overcomes the drawbacks inherent in the prior art in that the battery when connected does not apply a potential to the a.c.

circuit between the dynamo and the load when that a.c. circuit is operating. Hence, the a.c. circuit can stably function.

In a preferred embodiment, the module is for use with a rechargeable battery means, and further comprises rectifier means having inputs connected between said first and second conductive routes for receiving a.c. from the dynamo and d.c.

outputs connected across said battery terminals when said switching means is in said second state for recharging the rechargeable battery in use. With this arrangement the battery means is recharged by operation of the dynamo, and thus the battery means need not be replaced. Moreover, the isolation of the battery terminals from the first and second conductive routes ensures that the battery can be charged at the same time as the load is powered without interference between the a.c.

part of the circuit and the d.c. part of the circuit.

The outputs of said rectifier means are preferably connected to operating terminals of said switching means for switching the switching means between said first and second states. This enables the switching means to be operated by means of electrical power supplied by the dynamo without the need for an additional power source for the switching means. In addition, it is easily possible to arrange for the switching to the second state to be dependent on the d.c. output of the rectifier means.

In another preferred embodiment of the invention, the rectifier means comprises a rectifier bridge.

The module may further comprise a switch for making or breaking said first conductive route to the load. In this way, the supply of power to the load, be it from the battery means or the dynamo, can be directly controlled whilst the output of the rectifier means continues to recharge the rechargeable battery means in use when power is not being supplied to the load.

The switching means conveniently comprises a relay means; and the module may further comprise a housing mountable to a pedal driven vehicle for housing the module.

According to another aspect of the invention there is provided a lighting system for a pedal driven vehicle, the system comprising at least one lighting unit, a dynamo and a module as defined above.

Preferably, the lighting unit further comprises a rechargeable battery means so as to avoid the necessity to regularly replace worn out batteries.

According to a still further aspect of the present invention there is provided a pedal driven vehicle having an a.c. dynamo and a load, and a first conductive route between the a.c.

dynamo and the load and a second conductive route between the a.c. dynamo and the load to complete a circuit, the vehicle further including a module as defined above.

In this case, the second conductive route preferably comprises the vehicle frame as this is the common way to provide the second conductive route, particularly in cases where the power system for the load is already installed. Moreover, the use of the vehicle frame as the second conductive route has the advantage of reducing the number of connecting wires necessary for installing the module in the vehicle.

Preferably, the load includes one or more of lighting means, flasher means or alarm means.

A preferred embodiment of the invention will now be described in detail below, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a circuit diagram of a lighting system for a bicycle incorporating a power switching module embodying the present invention, Figure 2 illustrates a key operated switch for controlling varying accessories.

Referring now to figure 1, a power switching module 1 embodying the present invention is shown for fitting into an existing dynamo-powered lighting system for a bicycle comprising an a.c. dynamo 2 and one or more lights 3. The dynamo 2 is normally be connected to the bike frame via a mechanical attachment of the dynamo to the frame represented at 22. Similarly, the lights 3 are normally connected to the bike frame via a mechanical attachment to the lights to the frame represented at 15. Thus, a first electrically conductive route is formed along a wire connecting the a.c. dynamo to the lights and a second electrically conductive route is formed by the bike frame connecting the dynamo to the lights.

The power switching module 1 has a switching means in the form of a relay 5 having terminals 6 to 13. Terminal 7 is connected to a negative terminal 14 of a d.c. source in the form of a rechargeable battery, terminal 8 is connected to the bike frame at 19, terminal 12 is connected via a switch 4 to the lights 3, and terminal 11 is connected to the positive terminal 18 of the rechargeable battery. As mentioned above, the lights are also connected to the bike frame at 15.

The means for switching the relay will be explained below, but it functions as follows. Terminal 7 can be connected to either of terminals 8 or 9, and terminal 12 can be connected to either of terminals 10 or 11. The relay 5 has a first or normal state in which terminal 7 is connected to terminal 8 and terminal 12 is connected to terminal 11, and a second or further state in which terminal 7 is connected to terminal 9 and terminal 12 is connected to terminal 10.

In the normal state of the relay 5, which is when the dynamo 2 is not being driven or is only being driven very slowly, terminal 7 is connected to terminal 8, and terminal 11 is connected to terminal 12, as shown by the solid arrows in the drawing. Thus, the negative terminal 14 of the battery is connected via terminals 7 and 8 to the bicycle frame at 19, and the positive terminal 18 of the battery is connected via terminals 11 and 12 and switch 4 to the lights 3, which are in turn connected to the bicycle frame at 15 to complete a d.c.

lighting circuit. The d.c. lighting circuit thus supplies electrical power to the lights 3 in the situation that the dynamo speed is low or zero and if the switch 4 is closed.

Terminal 10 of the relay 5, which is connected to one side of the dynamo 2, is not connected to terminal 12 in this first or normal state so that an a.c. lighting circuit comprising the bicycle frame connected to the dynamo at 22, dynamo 2, terminals 10 and 12, and the lights 3, connected to the bicycle frame at 15, is not completed.

Terminal 10 and the one side of the dynamo 2 are connected to one of the input terminals of a rectifier means in the form of a rectifier bridge 21. The other input terminal of the rectifier bridge 21 is connected to terminal 8 and the bike frame at 19. The negative output terminal of the rectifier bridge 21 is connected to terminals 6 and 9 of the relay 5, and the positive output terminal of the rectifier bridge is connected to terminal 13 and to the positive terminal 18 of the rechargeable battery via resistor 16 and diode 17. Thus, another a.c. circuit is defined by the dynamo 2 connected across the input terminals of the rectifier bridge 21, the return of the. circuit comprising the bicycle frame via the connections at 19 and 22.

The dynamo output is rectified by the rectifier bridge 21 and the output is smoothed by a capacitor 20 connected across the output terminals of the bridge 21. This smoothed output is applied to terminals 6 and 13 of the relay 5. As stated above, the first or normal state of the relay is for terminal 7 to connect to terminal 8 and terminal 12 to connect to terminal 11. As the rotation speed of the dynamo 2 increases, the a.c output voltage of the dynamo 2 increases and thus the rectified d.c voltage applied to terminals 6 and 13 of the relay 5 also increases. When the voltage applied to terminals 6 and 13 exceeds a threshold value, the relay 5 functions to switch to its second or further state. Careful choice of components ensures that this happens substantially instantaneously when the dynamo is rotated.In the second or further state, terminal 7 is connected to terminal 9, and terminal 12 is connected to terminal 10, as shown by the dotted arrows in the drawing.

In this second or further state, the a.c. lighting circuit defined by the dynamo 2 connected via terminals 10 and 12, switch 4, the lights 5, and the bicycle frame at 15 and 22 is completed so that the dynamo 2 supplies a.c. electrical power to the lights 3 when the switch 4 is closed. At the same time, a completed d.c. charging circuit is defined by the output terminals of the rectifier bridge 21 connected via resistor 16 and diode 17 to the positive terminal 18 of the rechargeable battery, and via terminals 7 and 9 to the negative terminal 14 of the rechargeable battery. Thus, when the relay 5 is in th second or further state, the d.c. rectified output from the bridge 21 recharges the rechargeable battery, regardless of whether the switch 4 has been closed to complete the a.c.

lighting circuit supplying a.c. electrical power to the lights 3.

Importantly, when the relay 5 is in its second or further state the terminals 7 and 8 and 12 and 11 are no longer connected to each other so that the negative terminal 14 of the battery is not connected to the bicycle frame at 19 and the positive terminal 18 of the battery is not connected via the lights 3 to the frame at 15. Consequently, the d.c. charging circuit is isolated from the frame and the a.c. lighting circuit so that the d.c. potential does not influence the operation of the a.c.

lighting circuit or electrical components thereof.

When the speed of the dynamo and hence its output voltage falls, the rectified bridge output voltage applied to terminals 6 and 13 of the relay 5 will also fall. If this rectified voltage falls below the threshold value, the relay 5 switches from the further state back to the first or normal state; which step happens substantially instantaneously when the dynamo ceases to produce current, if the components are correctly chosen.

Referring to figure 2, there is shown a key controlled switch 31 having two contacts 31A and 31B. These contacts are connected to the terminal 12 so that a voltage for connection to earth is always supplied to the contacts 31A and 31B whether from the dynamo 2 or the battery terminals 14 and 18. In the off or locked position, shown in solid outline, the contact 31A connects to a contact 32 connected to a trembler alarm 35. In the event that the bike is rocked, during theft say, the alarms completes the circuit between terminal 12 and an electronic sounder 36 connected to earth. Thus, an electronic alarm is provided when the bike is locked and only power is supplied to the input of trembler alarm 35.

When the appropriate key is inserted into the lock of the switch 31, the switch is moved to the unlocked or on position shown in dotted outline. In this case, the contact 31A is disconnected from contact 32 and instead connects to a contact 33. The contact 33 is connected via a manually operable switch 38 to the electronic alarm 36 so that a horn is provided for the bike. A further contact 31B of the switch 31, which is not connected in the off state, makes contact with a contact 34 in the on state. The contact 34 is connected via the switch 4 to the lights 3 as shown in figure 1 so that the lights 3 can be controlled. The contact 34 also connects to a flasher unit 39, controlled by a manually operable switch 42 to control flashing of left hand indicators LF and RL connected to earth at 41 and right hand indicators RF and RR connected to earth at 41.

Thus, the key operated switch 31 can be moved to a locked position arming the alarm 35 and an unlocked position making available various electrical features of the bike.

It will be appreciated that the present invention can take many forms. For example, the module can come as part of a complete lighting system of a new bike or be retro-fitted to a bike already having a dynamo and lights. Alternatively, the module can be produced with a dynamo and lights to be fitted as a kit to a bike. Whilst the present invention has been described with reference to the use of the bike frame as an electrical conductor to provide a return via the connections 15, 19 and 22, it will be appreciated that when retro-fitting the module to many existing lighting systems, the connections 15 and 22 already exist. Thus, the connection 19 can comprise part of a connection to the bike frame of a housing containing the module. Of course, the connections 15, 19 and 22 could be replaced by a cable. The present invention is also applicable to a variety of dynamo types and can be used to power loads other than lights, for example indicator or alarm units.

Claims (16)

1. A power switching module for a pedal driven vehicle having a first conductive route between an a.c. dynamo and a load and a second conductive route between the a.c. dynamo and the load to complete a circuit, the module comprising:battery terminals for receiving battery means, and switching means connected in use to break into said first conductive route; the switching means having a first state connecting one battery terminal to the load via the first conductive route and the other battery terminal to the load via the second conductive route, and a second state when the dynamo output exceeds a threshold value wherein the dynamo is connected to the load via the first conductive route and isolating the battery terminals from the first and second conductive routes.

2. A module according to claim 1 for use with a rechargeable battery means, and further comprising rectifier means having inputs connected between said first and second conductive routes for receiving a.c. from the dynamo and d.c. outputs connected across said battery terminals when said switching means is in said second state for recharging the rechargeable battery in use.

3. A module according to claim 2, wherein the outputs of said rectifier means are connected to operating terminals of said switching means for switching the switching means between said first and second states.

4. A module according to claim 2 or 3, wherein said rectifier means comprises a rectifier bridge.

5. A module according to any preceding claim, further comprising a switch for making or breaking said first conductive route to the load.

6. A module according to any preceding claim, wherein said switching means comprises a relay means.

7. A module according to any preceding claim further comprising a housing mountable to a pedal driven vehicle for housing the module.

8. A lighting system for a pedal driven vehicle, the system comprising at least one lighting unit, a dynamo and a module according to any preceding claim.

9. A lighting unit according to claim 8, further comprising a rechargeable battery means.

10. A pedal driven vehicle having an a.c. dynamo and a load, and a first conductive route between the a.c. dynamo and the load and a second conductive route between the a.c. dynamo and the load to complete a circuit, the vehicle further including a module according to any of claims 1 to 7.

11. A vehicle according to claim 10, wherein the second conductive route comprises the vehicle frame.

12. A vehicle according to claim 10 or 11, further comprising a rechargeable battery means.

13. A vehicle according to any of claims 10 to 12 wherein said load includes one or more of lighting means, flasher means or alarm means.

14. A power switching module for a pedal driven vehicle having a first conductive route between an a.c. dynamo and a load and a second conductive route between the a.c. dynamo and the load to complete a circuit substantially as hereinbefore described with reference to the accompanying drawing.

15. A lighting system for a pedal driven vehicle having a first conductive route between an a.c. dynamo and a load and a second conductive route between the a.c. dynamo and the load to complete a circuit substantially as hereinbefore described with reference to the accompanying drawing.

16. A pedal driven vehicle having a first conductive route between an a.c. dynamo and a load and a second conductive route between the a.c. dynamo and the load to complete a circuit substantially as hereinbefore described with reference to the accompanying drawing.