GB2159671A

GB2159671A - Battery charging

Info

Publication number: GB2159671A
Application number: GB08507869A
Authority: GB
Inventors: William Griebel; Christopher Chinery
Original assignee: Jungheinrich Unternehmensverwaltung KG
Current assignee: Jungheinrich AG
Priority date: 1984-04-04
Filing date: 1985-03-26
Publication date: 1985-12-04
Also published as: DE3412541A1; GB8507869D0; GB2159671B; DE3412541C2

Abstract

Battery charging stations 1 to 7 are connected to a central station 15 serving at least as a unit for monitoring the charging operations. Audible or visual signals may be given by a common indicator 16 or respective indicators 16' in response to a deviation or malfunction at any charging station. The central station 15 may have either a display screen cyclically connected to each station 1 to 7 in succession, or respective screens (31) to (37), (Fig. 3), to monitor progress of the charging operations. A sensing circuit (18) and comparator (26), (Fig. 2), may be provided to reduce all the charging currents if their sum exceeds a reference level. Stations 1 to 7 may receive charging power from central station 15, or otherwise. Station 15 may have memories (38) to (44) (Fig. 4), (115) to (121), (Fig. 7), storing different charging programmes, the memories being associated with respective stations 1 to 7 or with batteries of respective kinds. One or more timing clocks may be provided at the central station 15 or stations 1 to 7 so that charging is effected at night. The charging operations may be timed to avoid charging a plurality of batteries simultaneously. The links 8 to 14 between stations 1 to 7 and 15 may be mains supply lines and these may carry superposed R.F. signals for monitoring and controlling the charging stations. Alternatively, the stations 1 to 7 and 15 may be connected by a ring line, stations 1 to 7 having address decoders. <IMAGE>

Description

SPECIFICATION Battery charging system This invention relates to a battery charging system comprising a plurality of charging stations, each of which comprises at least one charging voltage source.

Numerous battery-powered vehicle,s particularly industrial lifting trucks, are used in commercial enterprises and warehouses. The batteries of such vehicles must be recharged in dependence on their condition. It is known to provide special charging stations, to which the vehicles can be driven when the batteries are to be recharged. It is also known that batteries are to be recharged. It is also known that batteries can be removed from the vehicles and can be recharged outside the vehicle whereas each vehicle is always powered by a charged battery.

Premises in which such charging stations are provided have a substantial area. For this reason the charging stations are provided at spaced apart locations in such premises.

Such an arrangement will maintain the vehicles in an operative condition because each vehicle can be driven to the nearest charging station at the end of a working day or when a certain charge condition has been reached.

But that practice involves various disadvantages. Even if the batteries are charged overnight, the locations at which the vehicles are kept cannot be predetermined. If replaceable batteries are used, they must be kept in stock at various locations because the conditions of the batteries of the vehicle are not known.

Additional disadvantages are due to the fact that each charging station will involve a high expenditure if the batteries are to be charged under optimum conditions.

It is an object of the invention to provide a battery charging system which comprises a plurality of charging stations so tat the economy of operations involving a large number of batteries will be improved, the requirement for labour, i.e., for work, will be reduced, and operations involving battery-powered equipment can be performed under optimum conditions.

This object is accomplished in that the charging stations are connected to a central station which serves at least as a monitoring unit for monitoring the charging operations.

Owing to the centralized monitoring the labour requirement is reduced and the expenditure involved in decentralized charging stations may be restricted to the expenditure which is locally required. For instance, the quantity of spare batteries in each charging station may be restricted.

The monitoring of the charging operations includes also a check whether the charging operation is properly performed. Such check would otherwise have to be performed at each charging statio. For this reason the provision of the central station will greatly facilitate the planning of the operations of battery-powered equipment.

A special advantage will be afforded if the central station unit comprises at least one signal indicator for generating an error signal in response to a malfunction in any charging station. If a malfunction has thus been indicated, a serviceman will be sent to the charging station concerned, which need not be occupied by a serviceman throughout the time. A single signal indicator provided in the central station may be cyclically connected to the charging station. The central station is preferably provided with a signal indicator for each charging station. This will facilitate the supervision.

In a preferred emodiment the central station unit is provided with at least one display screen for selectively displaying the progress of a charging operation involving at least one battery. In that case the progress of the charging operation involving each battery can be monitored. This will be significant if batteryoperated vehicles used on different routes or in different regions of a plant have different travel workloads so that certain regions will require a special supervision.

From that aspect a particularly desirable embodiment of the invention comprises a central station provided with memory means for storing data representing the progress of charging operations performed in various charging stations and/or involving batteries of different kinds, and with comparators, which are associated with each memory unit and each of which will cause a signal indicator to generate a warning signal if the time required to increase the charge of a battery by a predetermined number of ampere hours exceeds the time required for such increase in a first charging operation performed in the associatec charging station or involving batteries of the associated kind.

In that case the command station constituted by the central station will receive an information that a certain battery used in the area served by the battery charging system must be replaced. As a result, an expensive improper operation of battery-powered equipment will be avoided.

In such battery charging system a timer consisting of a switch clock is preferably provided at or for each charging station. In that case a battery connected to a charging station, e.g., during the workday or at the end thereof, can be charged during a time in which inexpensive night current is available.

The provision of a charging station including such switch clock is an important feature.

Particularly in combination with a battery charging system the central station comprises monitoring and comparator means and over riding control means by which individual charging operations can be initiated at different times determined so as to avoid an overlapping of charging operations involving a plurality of batteries. This practice- involving the central station affords the important advantage that the system can be operated in such a manner tha the load on the mains will be reduced or equalized.

If batteries are connected to decentralized charging stations under the control of a switch clock so that favorable night current can be used, the provision of the overriding control means in the central station is essential for an optimum utilization of that advantage because the selected switch-on times which would otherwise coincide are now different. That practice will not adversely affect the charging operations because considerable time is available for the charging operation.

The timers may be provided in each charging station and in that case their time settings are communicated to the central station via functional links. In a desirable embodiment, timers for respective charging stations are incorporated in the central station.

In a particularly preferred embodiment all timers of the charging stations are connected to a monitoring circuit, which is provided in the central station and comprises a predetermined number of said switchable channels, which constitute a part of all switchable channels, are always energizable for the initiation of a charging operation, and a time-controlled disabling circuit is provided, which is arranged to disable the remaining switchable channels when switchable channels in that predetermined number are energized.In that case the load on the battery charging system will be monitored and determined only when the charging operations have been initiated at different times and in case of an overload caused by an operation of all charging stations in the charging stations which are monitored the programmed charging characteristics will be modified by charging characteristic controllers in such a manner that each charging operation will be extended in time. Such extension in time of the chargin characteristics may vary in dependence on the progress of charging operations performed in different charging stations and suitable control modules are provided for that purpose.

From that aspect a sensing circuit is desirably provided for sensing the charging currents in all charging stations, a comparator is provided, which is responsive to the total of the instantaneous charging currents, and the charging currents are adapted to be reduced when that total exceeds a predetermined limit set in the comparator. In such an arrangement, control modules may be provided for a controlled reduction of the charging currents.

In the preferred embodiment a battery charging system comprises controllers for a selection of charging characteristics and also comprises feedback lines, which lead from the changing stations to the central station and serve to transmit error signals to the central station when the battery parameters differ from the selected charging characteristics.

This is another advantage afforded by the central station.

Within the scope of the invention the charging stations are provided at the terminals connectable to the batteries with monitoring circuit, which have reference signal generators for a comparison of the output parameters determined by a selected charging characteristic and the parameters of a connected battery. Such monitoring circuits will deliver a feedback signal in response to improper conditions involving a connected battery.

It will be particularly advantageous in that case to provide in the central station an arrangement in which at least one program memory for storing different charging characteristics is adapted to be connected to the charging stations, a programmed charging characteristic is stored in each memory unit, and selecting and/or circuit-changing means are provided, which in response to a feedback signal transmitted via a feedback line and communicating data relating to the parameters of a connected battery are adapted to select any of different charging characteristics stored in respective memory units.

In that case the central station cannot only control a plurality of charging stations in dependence on their total load but can also control each of said charging stations in dependence on its load. This will result in a simplification because a control module for selecting a charging characteristic need not be incorporated in each charging station but a plurality of selectively operable controllers for determining respective charging characteristics may be provided in the central station and may be selected also in dependence on the parameters of a connected battery.

The monitoring by means of centralized signalling means can be performed as described.

The invention will now be described with reference to illustrative embodiments shown in the drawing, in which Figure 1 is a diagram showing a battery charging system comprisig charging stations and a central station.

Figure 2 is a circuit diagram showing a control circuit of the central station.

Figure 3 illustrates a special arrangement in a central station as shown in Fig. 1 with additional means.

Figure 4 is a diagrammatic representation of a specially designed central station.

Figure 5 shows a portion of a particularly desirable charging station.

Figure 6 is a diagrammatic representation showing a further arrangement in the central station for an additional modification.

Figure 7 is another diagrammatic representation showing an arrangement in the central station.

From the diagram of Fig. 1 it is apparent that, e.g., seven charging stations 1 to 7 are provided at spaced apart locations and are connected by functional links 8 to 14 to a central station 1 5. Each of said functional links comprises a plurality of lines, which may consist of load-sensing lines as well as of signal lines for transmitting signals in different directions.

In accordance with Fig. 1 the central station comprises a signal indicator 16 for generating an audible or visual signal. The signal indicator is connected to all functional links 8 to 14 by a cyclically operated switch module 1 7 and generates a signal in response to an electric error signal. As is indicated at 16', a plurality of signal indicators may be provided and may be associated with respective charging stations 1 to 7. In that case a deviartion or a malfunction in any charging station can be directly indicated.

In accordance with Fig. 2 the central station designated 1 5 in Fig. 1 comprises a sensing circuit 1 8 connected to all charging stations 1 to 7. That sensing circuit comprises a plurality of sensors 1 9 to 25, which are associaed with respective ones of the functional links 8 to 14 and measure the instantaneous charging currents. The output signals are delivered to a comparator 26, which determines the total of all charging currents and is connected to a presettable reference signal generator 27.

When the total of the charging currents exceeds the predetermined reference value indicated by the reference signal generator 27, the comparator delivers a signal via a functional line 28. As a result, a feedback signal is transmitted via the functional links 8 to 1 4 to the several charging stations 1 to 7 or, if power is supplied via the central station 15, a signal for reducing all charging currents supplied to connected batteries is delivered to the power pack.

Fig. 2 shows a central power line 29 connected to a connection panel 30, which is connected to the functional line 26. Alternatively, the functional line 28 is connected by branch lines to the functional links 8 to 14, by which the signals are transmitted to the charging stations, which in that case comprise control modules operable to reduce the connected loads.

The central station 1 5 shown in Fig. 3 comprises not only the signal indicators 16' but also comprises, e.g., display screens 31 to 37, which are connected in circuit and selectively energizable and can be used to monitor the progress of the charging operation involving an associated battery which has been connected. It will be understood that a single display screen may be provided and may be cyclically connected. This will permit a sampling operation whereas the arrangement shown in Fig. 3 permits a continuous monitoring and upon receipt of an error signal will immediately initiate a check and a compensating control.

Fig. 4 shows a modification with additional means in the central station 1 5. The incoming functional links 8 to 14 are connected to respective memories 38 to 44, in which different charging programs are stored. Each memory may comprise sections or compartments, in which individually selectable charging programs are stored with time marks.

Such memories 38 to 44 may be associated with respective charging stations 1 to 7 or with batteries of respective kinds, which are provided with respective code marks, which will be detected by any charging station to which the battery is connected and will effect a selection of the associated memory.

Reference signal generators 45 to 51 are associated with respective memories 38 to 44. Each of the reference signal generators 45 to 51 stores a threshold value, which has been determined during the first charging of a battery of a given kind or the first charging of a battery og a given kind or the first charging operation performed by a charging station associated with batteries of a given kind. Each of the reference signal generators 45 to 51 is coupled to one of the memories 38 to 44 by a comparator 52. By said comparators 52 the charging station parameters stored in the memories 38 to 44 are continually compared with the threshold values stored in the associated reference signal generator 45 to 51.

When the charging station parameter reaches that threshold value, which is represented by the threshold value signal of the associated reference signal generator 45 to 51 and which depends on the result of the first charging operation performed in the associated charging station or involving a battery of the associated kind, a selective warning signal is delivered via one of the lines 53 to 58 to one of the display fields of a display panel 59.

The monitoring and comparator means provided in the central station and comprising the comparators 52 may be connected to overriding control means 60, which are divided into corresponding sections and comprise terminals designated 61 to 66. In that case the several charging operations may be initiated at different times via a control line 67 of the times for which batteries are connected or charging operations are performed would otherwise overlap. Each of the charging stations 1 to 7 includes one of the trigger circuits 68 to 74 or such trigger circuits may be included in the central station 1 5 and connected to respective ones of the function links 8 to 14.

The charging station 75 shown in Fig. 5 comprises terminals 76 for connection to mains or to a charging voltage source and also comprises terminals 77 for connection to a battery. Said terminals are shown in the lower part of Fig. 5 and are coupled by a controller 78 for effecting a control in accordance with a charging characteristic. That controller 78, which may consist of a leakage transformer, is connected by function lines 79, 80 to a control module 81, which is coupled, e.g., by a make switch 82, to a timing clock 83, which is provided with setting means 84 for presetting the time at which the charging operation will be initiated after the make switch has been depressed.

The charging operation will not be initiated as soon as the make switch is depressed but will be initiated only after the time for which the timing clock 83 has been set has expired.

Such an arrangement affords important advantages because a low-cost night tariff can be utilized so that this embodiment constitutes a favourable charging station.

In other embodiments a timing clock 83 for each charging station may be incorporated in the central station or the central station may include a single timing clock, which is adapted to be coupled in sequence to all charging stations. This possibility is a further advantage afforded by the provision of a central station.

In a desirable embodiment shown in Fig. 6 the cengral station 1 5 is coupled to each of the functional links 8 to 14 by a monitoring circuit 85, which comprises switchable channels 86 to 92. All switchable channels are connected to a disabling circuit 93, which was disabling taps 94 to 100 and is adapted to automatically disable a number of the switchable channels 86 to 92 when an overload is detected by the disabling circuit.

In connection with that embodiment it is suitable to. provide the sensing circuit 1 8 and the comparator 26 because that combination will permit a particularly desirable control in dependence on the limit values.

In accordance with Fig. 6 each of the switchable channels 86 to 92 has associated with it one of the feeback lines 101 to 107, which serve to deliver signals to the associated functional links 8 to 14. Each of said feedback lines incorporates one of the control modules 108 to 114, which in dependence on the condition of the disabling circuit will initiate a charging operation or effect a change of a charging characteristic. The control modules 108 to 11 4 may also constitute signal input devices.

In accordance with Fig. 7 the central station 15 comprises program memory means preferably including a plurality of program memories 11 5 to 121 associated with respective functional links 8 to 14. Said program memory means are adapted to select different charging characteristics. One of the switches 1 22 to 128 is associafted with each of the program memories and is operable to couple the program memory to the associated functional link in response to trigger signals transmitted from the associated functional link via one of the branch leads 1 29 to 1 35 connecting the functional links 8 to 14 the control inputs of the switches 1 22 to 1 28.

Said branch leads 1 29 to 1 35 constitute switch control lines or feedbak lines and permit a selection of various charging characteristics which are stored in the program memories 115 to 121 and are selected for an adaptation to the batteries which are connected to the charging stations.

Various details of the central station are shown in the drawings. It will be understood that that representation has been chosen in order to facilitate the understanding and that features shown in various Figures of the drawing may suitable be combined in a central station.

In the Figures of the drawing the functional links 8 to 14 directly connect each of the charging stations 1 to 7 to the central station.

In accordance with Fig. 2 the functional links 8 to 14 may also be used to supply power from a power source 29 in the central station 1 5 to the charging stations, in which the power supply terminals of the functional link will then constitute the charging voltage source. Such an arrangement is desirable.

In another desirable embodiment the functional links 8 to 14 consist of mains, which carry superposed radiofrequency signals for monitoring and controlling the charging stations. In that case existing mains in the region in which the charging system is installed and operated may be used to provide functional links for transmitting superimposed monitoring and control signals.

In another desirable embodiment the charging stations 1 to 7 and the central station 1 5 may be connected by a ring line and the charging stations may be provided with address decoders. In that case the central station 1 5 comprises a computer in which the addresses are stored.

Claims

1. A battery charging system comprising a plurality of charging stations, each of which comprises at least one charging voltage source, characterized in that the charging stations are connected to a central station which serves at least as a monitoring unit for monitoring the charging operations.

2. A battery charging system according to claim 1, characterized in that the central station unit comprises at least one signal indicator for generating an error signal in response to a malfunction in any charging station.

3. A battery charging system according to claim 2, characterized in that the central station is provided with a signal indicator for each charging station.

4. A battery charging system according to any of claims 1 to 3, characterized in that the central station unit is provided with at least one display screen for selectively displaying the progress of a charging operation involving at least one battery.

5. A battery charging system according to any of claims 1 to 4, characterized in that the central station is provided with memory means for storing data representing the progress of charging operations performed in various charging stations and/or involving batteries of different kinds, and with comparators, which are associated with each memory unit and each of which will cause a signal indicator to generate warning signal if the time required to increase the charge of a battery by a predetermined number of ampere hours exceeds the time required for such increase in a first charging operation performed in the associated charging station or involving batteries of the associated kind.

6. A battery charging system according to any of claims 1 to 5, characterized in that a timer consisting of a switch clock is provided at or for each charging station and the central station comprises monitoring and comparator means and overriding control means by which individual charging operations can be initiated at different times determined so as to avoid an overlapping of charging operations involving a plurality of batteries.

7. A battery charging system according to claim 6, characterized in that a timer for each charging station is provided in the central station.

8. A battery charging system according to claim 6 or 7, characterized in that all timers of the charging stations are connected to a monitoring circuit, which is provided in the central station and comprises a predetermined number of said switchable channels, which constitute a part of all switchable channels, are always energizable for the initiation of a charging operation, and a time-controlled disabling circuit is provided,. which is arranged to disable the remaining switchable channels when switchable channels in that predetermined number are energized.

9. A battery charging system according to any of claims 1 to 8, characterized in that a sensing circuit is provided for sensing the charging currents in all charging stations, a comparator is provided, which is responsive to the total of the instantaneous charging currents, and the charging currents are adapted to be reduced when that total exceeds a predetermined limit set in the comparator.

1 0. A battery charging plant according to any of claims 1 to 9, comprising controllers for controlling charging characteristics characterized in that the links connecting the charging stations to the central station comprise feedback lines serving to transmit error signals to the central station when the battery parameters differ from the selected charging characteristics.

11. A battery charging system according to claim 10, characterized in that the charging stations are provided at the terminals connectable to the batteries with monitoring circuits, which have reference signal generators for a comparison of the output parameters determined by a selected charging characteristic and the parameters of a connected battery.

1 2. A battery charging system according to claim 10 or 11, characterized in that the central station is provided with an arrangement in which at least one program memory for storing different charging characteristics is adapted to be connected to the charging stations, a programmed charging characteristic is stored in each memory unit, and selecting and/or circuit-changing means are provided, which in response to a feedback signal transmitted via a feedback line and communicating data relaeting to the parameters of a connected battery are adapted to select any of different charging characteristics stored in respective memory units.

1 3. A battery charging system according to any of claims 1 to 12, characterized in that the functional links comprise mains adapted to transmit superimposed signals for monitoring and control purposes.

14. A battery charging system according to any of claims 1 to 12, characterized in that each charging station is directly connected by a functionaml link to the central station.

1 5. A battery charging system according to any of claims 1 to 13, characterized in that the charging stations and the central station are connected by a ring line and address decoders are provided in the charging stations.

1 6. A battery charging system according to claim 10, characterized in that the feedback lines are adapted to deliver signals to the functional links and incorporate control modules for varying the characteristic curves under the control of the disabling circuit.

1 7. A battery charging system substantially as described hereinbefore with reference to or as shown on the accompanying drawings.