GB2124441A

GB2124441A - Pedal cycle lighting system

Info

Publication number: GB2124441A
Application number: GB08310465A
Authority: GB
Inventors: Robert Paul Finch; Russell James Everett
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-04-21
Filing date: 1983-04-18
Publication date: 1984-02-15
Also published as: GB8310465D0; GB2124441B

Abstract

In a pedal cycle lighting system, negative half waves from an alternator G are passed via a diode D1 to a battery B1 and a front lamp L1 and positive half waves are passed via a diode D3 to a battery B2 and a rear lamp L2. Alternator G is connected to diodes D1, D3 via the primary of a current transformer T1, the secondary of which is connected via diodes D2, D4 to the batteries B1, B2 and lamps L1, L2. Transformer T1 increases the current available from alternator G at the expense of output voltage. Switches S1, S2 allow lamps L1, L2 to be directly connected to the primary of transformer T1, the batteries B1, B2 then being charged only from the transformer secondary and a resistor R then being connected across the primary. Charging current to the batteries may be smoothed by mutually coupled choker (CH1), (CH2), (Fig. 3). Means may be provided to limit the battery charging current, and the voltage applied to the lamps may be regulated, e.g. by a transistor or Zener diodes (Fig. 5). Series or parallel-connected lamps may be provided additionally or alternatively to lamps L1, L2 and connected across the series connected batteries (Figs. 4, 5). Solar cells to assist in battery charging, flashing direction indicators, and a radio or a cassette player may also be included. <IMAGE>

Description

SPECIFICATION Lighting systems for cycles The invention relates to lighting systems for pedal cycles.

According to a first aspect of the invention, a pedal cycle lighting system comprises batteries, a load connectable across the batteries, a source of alternating current and means for rectifying the alternating current, wherein rectified output current is applied directly across the batteries to charge the batteries and supply voltage to the load when the rectified output current is of sufficient quantity to exceed the battery voltage.

Preferably the system includes a current transformer having its primary winding connectable between one terminal of the source of alternating current and an input of the rectifying means.

The current transformer serves to increase the current available from the dynamo, at the expense of output voltage, and so provided enough current both to run the lamps and to recharge the batteries. If the voltage rating of the bulbs within the cycle lamps is matched to the battery voltage, the bulbs then operate under optimum conditions and can produce substantially constant light out-put at all road speeds.

In the system preferably the load comprises first and second lamps, the batteries comprise first and second batteries respectively associated with the lamps, and the rectifying means comprise first and second rectifying means respectively associated with the primary and secondary windings. The first rectifying means may have a first polarity output coupled to the first lamp and an opposite polarity output coupled to the second lamp, and the second rectifying means may have a first polarity output coupled to the first battery and an opposite polarity output coupled to the second battery, the circuits through the lamps and the batteries being returned, in use, to the other terminal of the source of alternating current.

Preferably the system includes first and second switching means for respectively coupling the first and second lamps selectively to the first and second batteries or to the output of the primary winding.

There may be included respective smoothing means connected between the second rectifying means and the first and second batteries and preferably the smoothing means are chokes.

Preferably the chokes are mutually coupled and are connected in opposed sense, and there are included first and second rectifiers arranged to form respective loops around the batteries and their associated chokes.

There may be included an impedance (preferably a resistor) arranged to be connected in parallel with the primary winding of the current transformer when the switching means connect the lamps to the output of the primary winding.

According to a second aspect of the invention, there is provided a pedal cycle having front and rear lamps, two batteries each connected across a respective lamp, a source of alternating current, and a full wave rectifier for rectifying the output of the alternating current source, the rectifier having a positive output node connected to the positive terminal of one battery and a negative output node connected to the negative terminal of the other battery, the other battery terminals being connected to the cycle frame acting as an earth and the alternating current source being connected to the rectifier by way of a current transformer having a primary winding connected between one output terminal of the source and a first input to the full-wave bridge rectifier, and a secondary winding connected between the second output terminal of the a.c. source and the second input to the full-wave bridge rectifier, the second output terminal of the a.c. source being also connected to the cycle frame as an earth.

According to a third aspect of the invention there is provided a pedal cycle having front and rear lamps, a source of alternating current, a first coupled to one of the lamps and the other of the alternating current source, one of the first pair of rectifiers having a positive output terminal coupled to one of the lamps and thecother of the first pair of rectifiers having a negative output terminal coupled to the other lamp, the alternating current source being connected to the first pair of rectifiers by way of a current transformer having a primary winding connected between one output terminal of the source and the input terminals of the first pair of rectifiers, the current transformer having a secondary winding connected between the second output terminal of the source, which is connected to the cycle frame, and the input terminals of a second pair of rectifiers, one of the second pair of rectifiers having a positive output terminal connected to the positive terminal of a first battery, associated with said one lamp, whose negative terminal is coupled to the cycle frame, the other of the second pair of rectifiers having a negative output terminal connected to the negative terminal of a second battery associated with said other lamp, whose positive terminal is coupled to the cycle frame, and respective switches for selectively connecting the lamps to their associated batteries or to the input terminals of the first pair of rectifiers.

An advantage of the circuitry proposed by the invention is that power is applied to the battery and to the cycle lamps without the use of any switching devices such as relays, thereby improving the reliability of the system.

The source of alternating current may conveniently be a hub type dynamo but the invention may alternatively make use of so-called "bottle dynamos" driven by frictional engagement with a tyre of the cycle.

The invention will now be described further, by way of example, with reference to the accompanying drawings in which: Figure 1 is a circuit diagram of a lighting system for a pedal cycle; Figure 2 is a circuit diagram of a modification of the circuit shown in Figure 1; Figure 3 is a modification of the circuit shown in Figure 1; and Figures 4 and 5 show alternatives of a further modification.

In Figure 1, a dynamo G, which may be a hub dynamo or a bottle dynamo, has one side connected to the cycle frame acting as earth and its other side connected to the primary winding of a current transformer Ti. The other end of the primary winding of the transformer T1 is connected to one input of a full wave rectifier constituted by diodes D1, D2, D3 and D4. The other input of the full wave rectifier is connected to one end of the secondary winding of the transformer T1 the other end of which is connected to earth.

The negative output node of the full wave rectifier is connected to the negative terminal of a battery B1 the positive terminal of which is connected to earth. The front lamp L1 is connected in parallel with the battery B1. On the other hand, the positive output node of the full wave rectifier is connected to the positive terminal of a battery B2, the negative terminal of which is connected to earth and in parallel with which the rear lamp L2 is connected. The connection between the battery terminals and the cycle frame may, if desired, be effected by way of a fuse.

In operation, the dynamo G generates an alternating voltage of approximately sinusoidal waveform. The positive and negative half cycles of this alternating voltage are rectified by diodes D3 and Dl,respectively, and applied to the batteries B2 and B1, respectively. The peak value of the alternating voltage waveform during each half cycle exceeds the terminal voltage of the batteries. The resultant currents flowing through D1 and D3 into the circuit nodes associated with the negative terminal of the battery B1 and the positive terminal of the battery B2 are limited by the internal impedance of the dynamo.

This a.c. current flowing through the primary of the transformer T1 induces a voltage in the secondary winding of the transformer which applies a voltage between earth and the second input of the full wave rectifier constituted by the junction between the diodes D2 and D4. The latter diodes D2 and D4 rectify the voltage in a manner analogous to the diodes D1 and D3. The unidirectional current thus attained supplements the currents passing through the diodes D3 and D1 into their respective circuit nodes.

The front and rear cycle lamps L1 and L2 are connected across the batteries B1 and B2, respectively. The voltage rating of the bulbs within these lamps is matched to the battery voltage and thus they operate under optimum conditions.

The lamps impose a constant current drain on their respective batteries. At average cycle speeds this drain is less than the total current flowing through D3 and D4 (in the case of L2) and D1 and D2 (in the case of L1) and thus the batteries experience a net current charging. At low or zero cycle speeds this situation is reversed and the batteries experience a net current drain.

As shown in Figure 2, a two-poie two-way switch S1, S2 can be incorporated such that in a first position (normal mode of operation) the circuit is the same as in Figure 1, and in a second position front lamp L1 is not connected to the battery B1 but is connected to the output end of the primary winding of the transformer Ti, thus short-circuiting diode D1.Analogously rear lamp 12 is not connected to the battery B2 but is connected to the output end of the primary winding thus short-circuiting diode D3.With the switch in this second position, as shown in Figure 2, the cyclist is provided with basic dynamo lighting and the batteries are recharged at the same time via the secondary of the transformer T1, and this second switch position should be selected should the batteries become fully discharged.

The load current for the batteries is constant but the charging current is in the form of full wave rectified sinusoid (with the switch in its normal first position), and the batteries experience alternate charging and discharging. This "cycling" could have a detrimental effect on some types of rechargeable battery and in a modified circuit, part of which is shown in Figure 3, the charging current provided via the secondary of the trans former1 is smoothed by a pair of mutually coupled chokes CH1 and ch2, respectively connected in opposed sense between diode D2 and battery Bland between diode D4 and battery B2.The secondary of the transformer T1 provides current pulses alternately to the positive and negative halves of the system, and the mutually coupled chokes CH 1 and CH2 of the system, and the mutually coupled chokes CH1 and CH2 provide smoothing to both halves at the same time with the help of a pair of diodes D5, D6 series-connected between the output terminals of diodes D2 and D4 in the manner of a bridge and with the midpoint of diodes D5 and D6 connected to the frame. With a suitable value of inductance for the chokes the current can be maintained above the load current and the "cycling" avoided.

When two-way switch is in its second position, the batteries could experience a higher charging current than when the switch is in its first (normal) position and this could have a detrimental effect on the batteries. This can be overcome or alleviated as shown in Figure 2 by connecting a suitable impedance R across the primary winding of transformer T1 when the switch is in its second position: conveniently, the switch can be three-pole two-way with the third section 53 used for this purpose. In the basic dynamo mode the current available for the lamps is limited by, inter alia, the impedance of the battery circuits being reflected into the primary of the transformer Ti, and the provision of a shunt impedance (preferably a small value resistor) will result in a larger current to the lamps.

Some types of rechargeable battery need to be charged from a constant current source, and this can be obtained in the system if the load on the dynamo is low compared with its ieakage reactance. However, a requirement may be to obtain a high power output by matching the load impedance to the dynamo, or approaching this condition, and under such a condition the constant current characteristic is unattainable. To limit the charging current in these circumstances an electronic or magnetic current limiting circuit could be used in the charging paths to the batteries. (This could be a current limiting resistor with high power rating).Thus if a high battery voltage is selected (for high lamp power) and/or a high "current magnification" factor is selected for the transformer T1, the nett battery charging current might be highly dependent on the rotational speed of the dynamo, and at high speeds the charging current might exceed the safe limit for the batteries and need to be limited.

Although the battery voltage is substantially constant, it may be desired to regulate the output voltage still further before applying it to the lamps and for this purpose a voltage regulating circuit may be employed. In a simple form this could be a power transistor in emitter follower configuration; alternatively zener diodes may be connected in the charging paths.

For safety purposes, it can be arranged that the front lamp extinguishes before the rear lamp as the batteries approach the fully discharge state.

The cyclist would be warned of this condition before the rear lamp had extinguished, and would switch to basic dynamo lighting with battery recharging. This can be achieved by connecting a suitable resistor in parallel with the front lamp, or by using a bulb with a greater current rating, ie. a higher power bulb.

Whereas in the above-described system the batteries are re-charged solely from the dynamo, they may be re-charged from, say, a domestic mains supply via a suitable transformer which may be situated at the domestic premises or built into the system.

The circuitry may be housed in a separate control box or built into the dynamo or the cycle lamps.

Further facilities which could be added to the above described lighting system are as follows:- 1. Flashing direction indicator, a radio or a cassette player, may additionally be provided, such facilities being powered by the rechargeable batteries.

2. Automatic or manual on/off switching may be designed such that the lamps are powered directly from the dynamo in the event of battery malfunction.

3. A fuse, preferably a slow operating fuse, may be included to protect the wiring from high currents that could occur in the event of a lamp being inadvertently short-circuited to the bicycle frame. Alternatively a solid state protection circuit could be used instead of the fuse(s).

4. In the case of the hub-type dynamos, a facility could be included whereby the batteries would be re-charged whenever the cycle is in motion (ie. the dynamo is producing an electrical output) irrespective of whether the lighting system is being used.

5. Solar cells may additionally be included to assist in re-charging the batteries.

As shown in Figures 4 and 5, a lamp or lamps may be connected directly across the two batteries, thus using both batteries in series. The lamp or lamps may be provided in addition to lamps L1 and L2 or as replacement therefor.

Figure 4 illustrates the case where two additional lamps are arranged in parallel one with the other are so connected.

Figure 5 illustrates a case where the two additional lamps are arranged in series. A respective Zener Diode is connected in parallel with each lamp so that in the event of fusing of one of the lamps, sufficient current may still pass for the other lamp to operate. Resistors R1, R2 and R3 are provided for current limiting purposes.

Although they may be omitted if so desired, their presence leads to two distinct advantages.

Firstly, the load current on the batteries is substantially constant whether neither, one or both bulbs are fused. Thus the batteries cannot be damaged by excessive charging current if either or both bulbs fuse. Secondly, the Zener Diode can also be used as output voltage regulators, whereby the voltages applied to the lamps can be regulated better than by the voltages of the batteries themselves.

Claims

1. A pedal cycle lighting system comprising batteries, a load connectable across the batteries, a source of alternating current and means for rectifying the alternating current, wherein rectified output current is applied directly across the batteries to charge the batteries and supply current to the load when the rectified output voltage is of sufficient quantity to exceed the battery voltage.

2. A system as claimed in Claim 1 and including a current transformer having its primary winding connected between one terminal of the source of alternating current and an input of the rectifying means.

3. A system as claimed in Claim 2, wherein said load comprises first and second lamps, said batteries comprise first and second batteries respectively associated with the lamps, and said rectifying means comprise first and second rectifying means respectively associated with said primary and secondary windings.

4. A system as claimed in Claim 3 wherein the first rectifying means has a first polarity output coupled to the first lamp and an opposite polarity output coupled to the second lamp, and the second rectifying means has a first polarity output coupled to the first battery and an opposite polarity output coupled to the second battery, the circuits through the lamps and the batteries being returned, in use, to the other terminal of the source of alternating current.

5. A system as claimed in Claim 4, wherein said first polarity outputs are coupled together, and said opposite polarity outputs are coupled together.

6. A system as claimed in Claim 4, including first and second switching means for respectively coupling the first and second lamps selectively to the first and second batteries or to the output of said primary winding.

7. A system as claimed in Claim 6, including respective smoothing means connected between the second rectifying means and the first and second batteries.

8. A system as claimed in Claim 7 wherein the smoothing means are chokes.

9. A system as claimed in Claim 8 wherein the chokes are mutually coupled, and are connected in opposed sense, and including first and second rectifiers arranged to form respective loops around the batteries and their associated chokes.

10. A system as claimed in any of Claims 6 to 9 wherein said first and second switching means are ganged two-way switches.

11. A system as claimed in any of Claims 6 to 10 and including an impedance arranged to be connected in paralled with the primary winding of the current transformer when said switching means connect the lamps to the output of said primary winding.

12. A system as claimed in Claim 11 wherein said impedance is a resistor.

13. A system as claimed in Claim 11 or Claim 12, when Claim 11 is dependant on Claim 10, wherein said impedance is connected by means of a switch ganged with said ganged two-way switches.

14. A system as claimed in Claim 2, wherein said load comprises first and second lamps, said batteries comprise first and second batteries connected together in series, and said rectifying means comprise first and second rectifying means respectively associated with said primary and secondary windings.

1 5. A system as claimed in claim 14, wherein said first and second lamps, connected together in parallel, are connected directly across the terminals of said batteries.

1 6. A system as claimed in claim 14, wherein said first and second lamps are connected in series across the terminals of said batteries.

1 7. A system as claimed in claim 16, wherein said first and second lamps are each connected in parallel with a respective zener diode.

1 8. A system as claimed in any of Claims 3 to 1 7 wherein one of said lamps has a higher current rating than the other lamp.

19. A system as claimed in any of Claims 3 to 17 and wherein one of the lamps has a resistor connected in parallel so as to impose a greater current drain on its associated battery than the current drain on the other battery.

20. A system as claimed in any of the preceding Claims and including current limiting means for limiting the charging current supplied to the batteries.

21. A system as claimed in any of the preceding Claims and including means for regulating the voltage of the rectified output.

22. A system as claimed in any one of the preceding claims and including fuse means for protecting circuit wiring in the event of a short circuit condition.

23. A system as claimed in Claim 20 and wherein the fuse means is slow to operate.

24. A system as claimed in any of the preceding Claims and including a transformer connectable to the rectifying means and, in use, to a source of mains voltage.

25. A system as claimed in any of the preceding Claims and including solar cells arranged to provide a source of electrical current for charging the batteries.

26. A lighting system substantially as herein described with reference to Figure 1 or Figure 2, or Figure 1 or Figure 2 when modified in accordance with Figure 3, or Figure 4 or Figure 5 of the accompanyiny drawings.

27. A pedal cycle having a lighting system as claimed in any one of the preceding Claims.

28. A pedal cycle having front and rear lamps, two batteries each connected across a respective lamp, a source of alternating current, and a full wave rectifier for rectifying the output of the alternating current source, the rectifier having a positive output node connected to the positive terminal of one battery and a negative output node connected to the negative terminal of the other battery, the other battery terminals being connected to the cycle frame acting as an earth and the alternating current source being connected to the rectifier by way of a current transformer having a primary winding connected between one output terminal of the source and a first input to the full-wave bridge rectifier, and a secondary winding connected between the second output terminal of the a.c. source and the second input to the full-wave bridge rectifier, the second output terminal of the a.c. source being also connected to the cycle frame acting as an earth.

29. A pedal cycle having front and rear lamps, a source of alternating current, a first pair of rectifiers for rectifying the output of the alternating current source, one of the first pair of rectifiers having a positive output terminal coupled to one of the lamps and the other of the first pair of rectifiers having a negative output terminal coupled to the other lamp, the alternating current source being connected to the first pair of rectifiers by way of a current transformer having a primary winding connected between one output terminal of the source and the input terminals of the first pair of rectifiers, the current transformer having a secondary winding connected, which is connected to the cycle frame, between the second output terminal of a source and the input terminals of a second pair of rectifiers, one of the second pair of rectifiers having a positive output terminal connected to the positive terminal of a first battery, associated with said one lamp, whose negative terminal is coupled to the frame, the other of the second pair of rectifiers having a negative output terminal connected to the negative terminal of a second battery, associated with said other lamp, whose positive terminal is coupled to the cycle frame, and respective switches for selectively connecting the lamps to their associated batteris or to the input terminals of the first pair of rectifiers.

30. Means, relating to an essential element of the invention, suitable for putting or intended to put into effect the invention defined in any of the preceding claims.