GB2075283A - Battery charging equipment - Google Patents

Abstract

Battery (2) charging equipment is provided with rechargeable cells (47) which, in the event of mains power failure, control the activation of a timer- oscillator circuit 22 to ensure that a preselected charging period is correctly completed when the mains is restored. <IMAGE>

Description

SPECIFICATION Battery charging equipment This invention relates to battery charging equipment. In particular, although not exclusively, the present invention relates to battery charging equipment for recharging batteries of battery powered monitors used for sensing the mine atmosphere in an underground mine.

Known battery charging equipment comprises timer means for timing the recharging period of each battery such that under normal recharging procedure each battery is recharged for a preselected period. Unfortunately, if the power supply to the charging equipment is broken, control of the timer means is lost and upon the power supply being re-connected to the charging equipment each bat terycharging period is reset either to a start or finish charging setting. Consequently, the charging periods of the batteries which were on charge at the time when the power supply was interrupted tend not to be the desired charging period.

An object of the present invention is to provide improved battery charging equipment which tends to overcome or reduce the above mentioned disadvantage.

According to the present invention, battery charging equipment comprises connector means for temporarily, electrically connecting at least one rechargeable battery to the charging equipment, converter means adapted to receive mains electrical power supply and to feed desired recharging power to rechargeable means, and timer means for determining the recharging period of the or each battery on charge, the rechargeable means being adapted to be recharged from the mains power supply and to control operation of the timer means should the mains power supply charging equipment to be interrupted.

Preferably, the timer means comprises a number of timer units, the number of timer units being equal to the number of batteries capable of being charged simultaneously by the charging equipment.

Conveniently, the or each timer unit comprises an integrated circuit including an oscillator.

Preferably, the oscillator is an on-chip oscillator, the frequency of which is determined by a capacitor.

Conveniently, a variable resistance is provided for fine adjustment of the frequency of oscillation.

Preferably, the rechargeable means comprises of transistor arranged to control operation of the oscillator.

Preferably, a capacitor is mounted in series with the transistor.

By way of example only, one embodiment of the present invention will be described with reference to the accompanying drawing which shows an electrical circuit diagram of a part of battery charging equipment constructed in accordance with the present invention.

The drawing shows one connector means 1 of a number of similar connector means, for example ten, for temporarily, electrically connecting a rechargeable battery 2 to the battery charging equipment, the rechargeable battery 2 being used to supply power to a battery powered monitor for sampling mine atmosphere in an underground coal mine. The connector means 1 is fed with desired recharging power from converter means 3 which is adapted to receive mains electrical power supply, the converter means converting the main power to, for example a constant charging current of four hundred and fifty milliamperes.The connector means 1 is arranged to feed the recharging current to contacts 5 and 6 engaged by the battery 2 and to a terminal 7 which in turn feeds the constant charging current to the second and subsequently connecting means which as previously stated are similar to connecting means 1 and which are connected in series.

The connector means 1 also comprises a two-way switch 10 which is activated to feed power to the contacts 5 and 6 when the battery 2 is placed on the charging equipment in engagement with the contacts, the battery abutting the switch to move the switch contact into an operational mode opposite to that shown in the drawing. Operation of the switch 10 simultaneously activates a two-way switch 12 provided in a timer unit 13 of timer means discussed later in the specification. A diode 11 is provided to prevent power being fed from the battery 2 into the charging equipment.

A further switch 15 provided in the connector mean circuit is activated by an energising relay 16 provided in the timer unit 13, as will be explained later the switch 15 is activated by the energising relay 16 to close line 14 and stop the full charge power to the battery 2 after a preselected charging period, for example, twelve hours. After the switch 15 is activated to stop full charging power to the battery 2, a topping-up trickle charge feed is maintained through the contacts 5 and 6, the rest of the full charge being fed through the switch 15, a light emitting diode 17 and resistances 19 and 20 which determine the flow along the associated lines arranged in parallel. Thus, the light emitting diode is lit only when the switch 15 is closed and a trickle charge is being fed to the battery 2.Hence, the light emitting diode 17 gives an indication when the battery is fully charged and ready for use. The trickle charge maintains the battery 2 fully charged while ever it is mounted on the charging equipment but is of insufficient powerto overcharge the battery.

The resistance 18 is provided to ensure correct current flows to the terminal 7 when the battery 2 is removed from the charging equipment and the switch 10 takes up the operational mode as shown in the Figure to cut off power to the contacts 5 and 6.

As mentioned previously the charging period of the connector means 1 is determine by the energised relay 16 provided in a timer unit 13 of timer means which provides a similar timer unit for each of the plurality of connector means. The timer unit 13 comprises an integrated circuit 22, for example a commercially obtainable Ferranti Precision Timer Integrated Circuit No ZN1034E, which includes an on-clip oscillator (not shown) the operational frequency of which is determined by a capacitor 54.

Time adjustment of the frequency is achieved by varying the setting of a potentiometer 24 and by the provision of a capacitor 23. The integrated circuit also comprises a timer component for determining the length of operation of the oscillator, the timer component counting the oscillations generated by the oscillator A regulated power supply is fed to pin 5 of the integrated circuit from one terminal 25 of a set of terminal 25, 26 and 27 electrically connecting the timer circuit to a regulated power source unit 28, the supply to pin 5 passing from terminal 25 along line 29 and the previously mentioned switch 12 is activated by the mounting of the battery 2 onto the connector means 1 to feed power to the integrated circuit to start the timer circuit for the preselected desired charging period.The timed output from the integrated circuit is fed from pin 3 to the base of a transistor 30 controlling electrical flows along line 31 from the teminal 26 to the earth line 32 and thereby controlling operation of the energising relay 16 which in turn controls activation of the switch 15.

The earth line 32 is connected to the earth terminal 27.

A light emitting diode 33 indicates when electrical current is flowing in line 31 and the relay 16 is energised. Thus, the light emitting diode 33 thereby gives an indication that the battery 2 is on charge.

Conveniently, the light emitting diodes 33 and 17 are coloured red and green, respectively.

A diode 35 is arranged in parallel with the energising relay 16 to prevent damage to the transistor 30. Resistances 36 and 37 are provided in line 29 and the line connecting pin 3 to the base of the transistor 30, respectively.

A capacitor 38 is provided between the input pin 5 and earth pin 7 of the integrated circuit.

The set of terminals 25, 26 and 27 also provide a regulated power supply to the other timer units of the timer means along lines 40,41 and 42 and to rechargeable means 46 including a number of rechargeable battery cells 47, control means 48 for selectively controlling each timer unit 13, and a switch 50 linked to a mains on-off switch assembly 51 provided on a mains transformer unit 52.

The control means 48 comprises a transistor 54 connected between the earth line 32 and an input pin 13 of the on-chip oscillator unit within the integrated circuit 22, the frequency of oscillation being determined by the previously mentioned timing capacitor 56 arranged in series with the transistor 54 and by timing resistances 57 and 58 connecting the timing capacitor 54 to the power supply pin 14 of the integrated circuit 22 providing a regulated power supply to drive the oscillator.

A diode 59 is mounted across the transistor 54to prevent damage to the transistor and a resistance 60 is provided in line 61 connecting terminal 26 to the base of the transistor 54.

The mains transformer unit 52 comprises a set of terminals 63,64 and 65 for connecting the unit to a mains supply (not shown), the terminals 63 and 64 being connected to the transformer primary coil via the previously mentioned switch 51. The transformer secondary coil feeds the power supply via a rectifier unit 66 and fuse 67 to input terminals 68 and 69 of the regulated power source units 28 which together with the transformer unit constitutes converter means adapted to receive mains electrical power supply and feed a desired recharging power to the rechargeable means 46. A capacitor 70 is mounted across the output from the rectifier unit66.

The regulated power source unit 28 comprises an integrated circuit 72 having input pins 31 and 41 connected to the terminals 68 and 69, respectively.

Two transistors 73 and 74 and a plurality of resistances 75,76,77,78, and 79 are provided to achieve the desired regulated output which is fed via pin 8 to the terminals 25 and 26. The earth terminal 27 is connected to the earth pin 41. A diode 80 is provided to prevent electrical power being fed from rechargeable means 46 via terminal 25 to 26. Fine adjustment of the regulated power supply to terminal 25 is controlled by resistances 81,82 and 83 and a capacitor 84. Further capacitors 85 and 86 are arranged across the terminals 68 and 69, and 25 and 27 respectively.

In use, with mains power supplied to the charging equipment a battery 2 mounted on the charging equipment activates the switch assembly 10, 12 to feed a charge to the battery via contacts 5 and 6.

Also, activation of the switch 12 closes the associated timer unit circuit to feed regulated power from the terminal 25 to the input pin 5 of the integrated circuit 22 to start driving the oscillator and timer component provided by the integrated circuit.

Simultaneously, a signal is fed from pin 3 of the integrated circuit 22 to the base of the transistor 30 which conducts to permit current to flow along line 31. The light emitting diode 33 is activated and the relay is energised to open switch 15 to stop flow through resistances 19 and 20 and light emitting diode 17.

If the mains is supplied continuously throughout the recharging period the oscillator and timer component will continue to function normally and after the preselected charging period the timer compo next will remove the signal from pin 3 to the base of the transistor 30 which thereby is deactivated and prevents flow along line 31. The light emitting diode 33 is de-activated and the relay 16 is de-energised permitting the switch 15 to close and allowing fltrw of charging current through resistances 19 and 20 and the light emitting diode 17 is activated indicating the charge period is ended. As explained earlier a trickle charge flows through the contacts 5 and 6 until the battery is removed.

Throughout the period mains power is supplied to the charging equipment a regulated power supply is fed from the converter means terminals 25 and 27 to the rechargeable means 46 to recharge the battery cells 47. The flow of charge is insufficient to over charge the battery cells.

However, if during the charging period the mains power supply is interrupted, then immediately power is fed from the rechargeable means 46 to the terminals 25 and 27. The power on terminal 25 from the battery cells 47 is prevented from reaching terminal 26 by the diode 80. Thus, the signal is removed from the base of the transistor 54 and the oscillator provided by the integrated circuit 22 is stopped. However, the power on terminal 25 is fed via line 29 to the input pin 5 of the integrated circuit 22 and this power supply is sufficient to control activation of the timer component which as the oscillator is stopped effectively remains stationary.

Also the light emitting diode 33 and relay 16 are de-energised to prevent unnecessary loss of energy.

Upon the mains power supply being reconnected to the charging equipment power once again is fed from the regulated source 28 to the terminals 25 and 26 and the osillator on the integrated circuit 22 is re-started. Hence, the timer component recommences counting the oscillations, the charging period progressing from the time it had reached when the mains power supply was interrupted. Thus, the battery 2 is given the desired period of charge irrespective of the temporary failure of the mains power supply.

The same procedure is followed by each timer unit of the charging equipment.

Claims (9)

1. Battery charging equipment comprising connector means for temporarily, electrically connecting at least one rechargeable battery to the charging equipment, converter means adapted to receive mains electrical power supply and to feed desired recharging power to rechargeable means, and timer means for determining the recharging period of the or each battery on charge, the rechargeable means being adapted to be recharged from the mains power supply and to control operation of the timer means should the mains power supply charging equipment be interrupted.

2. Equipment as claimed in claim 1, in which the timer means comprises a number of timer units.

3. Equipment as claimed in claim 2 in which the number of timer units is equal to the number of batteries capable of being charged simultaneously by the charging equipment.

4. Equipment as claimed in any preceding claim, in which the or each timer unit comprises an integrated circuit including an oscillator.

5. Equipment as claimed in claim 4 in which the oscillator is an on-chip oscillator, the frequency of which is determined by a capacitor.

6. Equipment as claimed in claim 4 or claim 5 in which a variable resistance is provided for fine adjustment of the frequency of oscillation.

7. Equipment as claimed in any one of claims 4, 5 or 6 in which the rechargeable means comprises of transistor arranged to control operation of the oscillator.

8. Equipment as claimed in claim 7 in which a capacitor is connected in series with the transistor.

9. Battery charging equipment substantially as hereinbefore described with reference to the accompanying drawing.

9. Battery charging equipment substantially as hereinbefore described with reference to the accompanying drawing.

New claims filed on 30 Jan 81 Superseded claims 1 - 9 New claims

1. Battery charging equipment including connector means to which a battery to be recharged can be removably connected, the connector means being controlled by timer means and arranged to supply for a predetermined period a charging current derived from a main power supply via converter means to the battery to be recharged, the converter means also supplying a charge to an auxiliary battery incorporated in rechargeable means to keep the auxiliary battery in a state of charge, in which the rechargeable means includes switching means whereby on the temporary cessation of the mains power supply the auxiliary battery is connected to supply power to the timer means to hold it in a suspended state so that on the restoration of the mains power supply the timer continues to operate for the unexpired portion of the predetermined period.

2. Equipment as claimed in claim 1, in which the timer means comprises a plurality of timer units.

3. Equipment as claimed in claim 2 in which each timer unit is capable of charging simultaneously with the other units a separate battery connected to it.

4. Equipment as claimed in any preceding claim, in which the or each timer unit comprises an integrated circuit including an oscillator.

5. Equipment as claimed in claim 4 in which the oscillator is an on-chip oscillator, the frequency of which is determined by a capacitor.

6. Equipment as claimed in claim 4 or claim 5 in which a variable resistance is provided for fine adjustment of the frequency of oscillation.

7. Equipment as claimed in any one of claims 4,5 or 6 in which the rechargeable means comprises of transistor arranged to control operation of the oscillator.

8. Equipment as claimed in claim 7 in which a capacitor is connected in series with the transistor.