GB2041328A - Improvements in or Relating to Liquid Dispensing Apparatus - Google Patents

Abstract

Apparatus for dispensing a liquid, such as topping-up fluid for wet-cell batteries. The apparatus has a frame which is arranged for supporting a liquid container and an electric pump to dispense liquid to a probe 22. The probe has a metallic nozzle 25 for pumped liquid, and at least one electrode 27 spaced from the free end of the nozzle 25. A detecting circuit is connected to the nozzle 25 and electrode 27 and is adapted to inhibit operation of the pump when a circuit is completed by liquid between the nozzle 25 and electrode 27. The probe 22 has an abutment face 24 to ensure insertion of the nozzle to the correct position in a vessel to which liquid is to be dispensed. A further electrode 28 may be provided to allow the circuit to give an indication if the liquid in the vessel is below a minimum level on insertion of the probe. <IMAGE>

Description

SPECIFICATION Improvements in or Relating to Liquid Dispensing Apparatus This invention relates to apparatus for dispensing liquids, and in particular-but not exclusively-to apparatus intended for dispensing distilled or de-ionised water for topping up wetcell batteries. Though the apparatus of this invention could be used for dispensing a wide variety of liquids into vessels to a pre-determined depth, the invention will however be particularly described hereinafter with reference to the topping-up of the cells of wet batteries.

In.a relatively large scale wet-cell battery installation, such as may be found as a stand-by power supply or in a telephone exchange, it is most important that each cell of the battery be maintained in good condition. Of prime importance is that the electrolyte be maintained at the required specific gravity, and for this, it is essential that the level of the electrolyte be maintained within closely-controlled limits.

Usually, the maximum and minimum limits are marked on the side of the vessel of each ceil of a battery installation, and refilling with distilled or de-ionised water is performed manually, as and when required. Not only is this a time consuming task, but it is also open to considerable errors since it is usually performed by relatively unskiiled labour. For example, if a cell is overfilled with water, the electrolyte is diluted and the cell cannot perform efficiently; this can then affect the operation of an entire battery. Of course, if an operator overfills a cell and then removes some liquid to re-establish the correct level, the specific gravity of the remaining liquid will be incorrect.

It is an object of this invention to provide apparatus for dispensing a liquid, such as distilled or de-ionised water, for filling to a pre-determined level a vessel such as a cell of a wet battery.

In accordance with this invention, there is provided apparatus for dispensing a liquid, which apparatus comprises a wheeled frame adapted for mounting a container of the liquid to be dispensed, the frame supporting electrically operated pump means for pumping liquid from a mounted container, a dispensing probe connected by a flexible hose to the output of the pump means, there being at least one electrode arranged on the probe spaced from the free end thereof, and a detector circuit in electrical connection with the electrode and arranged to sense whether or not the electrode contacts liquid in a vessel when the probe has been inserted into the vessel to a predetermined position, the detector circuit serving to inhibit the operation of the pump means when the electrode is contacted by liquid in the vessel.

In order that the electrode on the probe of this invention may accurately be positioned within a vessel at the required depth, it is preferred for the probe to be provided with some form of datum referencing means. For example, for filling any given design of vessel, the probe could have a marking which is to be aligned with the top of the vessel to be filled. In the case of a wet-cell battery, each cell usually has a vent opening through which it can be filled. For such a cell, the probe may have an abutment shoulder which is to be engaged with the cell wall defining the vent opening. When so engaged, the lowermost part of the electrode should be adapted to lie at the required depth of electrolyte in the cells.Such an arrangement may of course be used with a wide variety of cells, provided the walls defining the vent are similarly disposed with respect to the required electrolyte level on each type.

Preferably, a second electrode is provided on the probe, nearer the free end of the probe than the first-mentioned electrode, the second electrode also being electrically connected to the detector circuit, such that the detector circuit may give an indication if the liquid level is below the second electrode. By suitably positioning the firstmentioned and second electrodes, the detector circuit may give an indication if the liquid in the vessel is below a minimum level or between the minimum and maximum levels, in either case the operation of the pump means not being inhibited, as well as the detector circuit inhibiting operation of the pump means once liquid has been added to bring the depth of the liquid to the position of the first-mentioned electrode.

For convenience, so as to reduce the complexity of the probe and the number of wires needed to interconnect the probe and the detector circuit, it is preferred for at least the free end of the liquid dispensing part of the probe itself to be conductive so as to constitute a further electrode with which a circuit including either the first-mentioned electrode or the second electrode may be completed, and detected by the detector circuit.

The detector circuit may be fully self-contained and include its own power supply, and for certain circumstances of filling vessels with liquid, this may be an advantageous arrangement. However, so far as the filling of the cells of the battery is concerned, it is convenient for the detector circuit to be provided with means for connecting the detector circuit to a cell or cells of the battery itself, thereby to allow the circuit to draw power from the cell or cells. However, in order that the power supplied by the battery will not interfere with the proper operation of the detector circuit when the probe and electrodes are within a cell, the power supplied to the detector circuit must electrically be isolated from the probe.

Conveniently, this may be achieved by means of a DC/DC converter, which essentially consists of a solid state AC generator driving an isolating transformer, the output of which is rectified to produce the required DC power supply for the detector circuit.

For the case in which the detector circuit is driven by a cell or cells of a battery to be topped up by the apparatus of the invention, the detector circuit is conveniently connected to the cell or cells by a pair of leads appropriately connected to a diode bridge network. By taking the power from the opposed connections of the bridge network, the polarity of the connecting leads is not important and power will be supplied with the correct polarity to the detector circuit irrespective of the connection of the leads.

It is preferred for the detector circuit to function in such a way that should the firstmentioned electrode not complete a circuit to the detector circuit (that is to say, the first-mentioned electrode is not contacting liquid in the vessel) an indication is given of this, for instance by illuminating a lamp, to show liquid should be added. The detector circuit preferably includes a control circuit for the pump means and in the above condition, energisation of the pump may be effected by operating a switch. Once energised, the pump may pump liquid from a container carried by the frame until the liquid level in the vessel contacts the first-mentioned electrode, whereafter it is preferred for another indication to be given (for instance, by a lamp of a different colour or by an audible alarm) and for the pump means automatically to be de-energised.In this way, a cell of a battery installation cannot be over-filled. The detector circuit can further be improved by connection to a second electrode arranged as discussed above, a further lamp being illuminated if no circuit is made with the second electrode, when the probe is first inserted in a vessel, to show that the liquid level is below a minimum.

The just-described arrangement has the further advantage that if when topping up a battery installation consisting of many cells, one of the cells causes the lamp associated with the second electrode to be illuminated, an operator is given an indication that there is probably something wrong with that particular cell, causing rapid evaporation of electrolyte therefrom. The operator may of course top up that cell in the usual way, but nevertheless may note the fact that further investigation may be necessary.

The detector circuit may be built into a housing provided on the frame of the apparatus or preferably is arranged within a separate control box which may be carried by the frame or by an operator also carrying the probe. In the latter case, the control box must appropriately be connected to the pump means and so on by flexible leads of a sufficient length to allow the operator adequate freedom of movement.

It will be appreciated that the apparatus of this invention is portable insofar as a wheeled frame is provided allowing the apparatus easily to be moved around a battery installation or other area where vessels are to be filled with liquid. The frame may thus support a relatively large container for liquid and yet may easily be moved from one vessel to another. Using the apparatus of this invention, an operator is less likely to make mistakes through either adding too much liquid or not enough to a vessel requiring an addition to bring the liquid level to a predetermined depth.

By way of example only, one specific embodiment of this invention will now be described, reference being made to the accompanying drawings, in which: Figure 1 is a side view of part of the apparatus of this invention; Figure 2 is a front view of the part of the apparatus shown in Figure 1; Figure 3 is a side view of a probe for use with the apparatus of Figure 1; Figure 4 is a block diagram of a detector circuit incorporated in the apparatus of Figure 1; and Figure 5 is a schematic circuit diagram of the detector circuit shown in Figure 4.

Referring initially to Figures 1 and 2, it can be seen that the apparatus of this invention includes a frame 10 provided with three wheels 11, 12, and 13, wheel 13 being provided with a castor arrangement. The frame also includes a pair of handles 14 by means of which the frame may easily be moved around. The front of the frame (having regard to the disposition of the handles 14) is adapted to support a container 1 5 for liquid such as distilled or de-ionised water. The container is retained on the frame by means of upstanding lugs 1 6 and a strap 1 7 clipped to braces 18 for the handles 14.

Also provided on the frame 10 is a housing 19 for an electrically-operated pump (not shown) the input of which is connected to a hose 20 leading into the container 15, the hose 20 having at its free end an intake filter (not shown) to prevent the ingress of foreign matter. Above the housing 19, there is provided a storage compartment 21 for a control box (not shown) which contains an electronic control and detector circuit, described below.

Figure 3 shows a probe 22 for dispensing liquid pumped by the electrically-operated pump contained within the housing 19. The probe includes a manually grippable portion 23 and a nozzle assembly 24, the end of the portion 23 remote from the nozzle 24 being provided with pipes and connectors for water and electrical cables.

The nozzle assembly 24 includes a liquid dispensing tube 25 connected through the handle portion 23 to the pipe 26. The nozzle assembly 24 also has two electrodes 27 and 28, electrode 27 being the shorter and electrode 28 terminating adjacent the free end of the dispensing tube 25.

The electrodes 27 and 28 as well as the tube 25 are made of a conductive material such as stainless steel, and are connected by separate, insulated wires back through the handle portion 23 to an electrical plug 29. The pipe 26 is provided at its free end with a quick-release coupling, to allow the connection of a flexible hose from the probe 22 to the outlet of the pump contained within the housing 1 9. The plug 29 is adapted for insertion into a socket at the end of a flexible electrical cable which connects the probe to the control box mentioned above.In use, the probe is inserted into a battery cell to be topped up until an abutment shoulder 22' on the probe contacts a suitably-formed wall (not shown) of the cell, in which position the free end of the tube 25 is below the minimum electrolyte level, and water is added until electrode 27 is contacted by the electrolyte.

Referring now to Figure 4, there is shown a block diagram of the control and detector circuit contained within the control box. The circuit is arranged for checking the electrolyte level in the cells of a battery 30, which supplies power to a circuit 31 to deliver current at the correct polarity and within the correct potential range to the remainder of the circuit. The electrically operated pump 32 can be driven from the potential source circuit 31, to pump liquid from a reservoir 33 to the probe 22 and thus into the battery 30, on operation of a pump switch 34.

Connecting leads 35 and 36 are respectively connected to electrodes 27 and 28, to control the operation of switches 37 and 38 respectively. The positions of the switches 37 and 38 are shown by indicators 39 and 40 respectively, each switch having a latching arrangement 41 and 42 respectively. Thus, if so little liquid is in a cell being topped up that the lower electrode 28 does not contact the liquid, an indication is given on indicators 39 and 40, whereas when sufficient liquid has been added so that the liquid contacts the shorter electrode 27, switch 37 operates and latches and an indication to this effect is given on a further indicator 43. At the same time, when switch 37 latches, inhibit element 44 is operated, to prevent further operations of the pump 32, even if the "add water" switch 34 is still closed.

Switches 37 and 38 can be tested respectively by test switches 45 and 46 respectively, simulating the action of liquid contacting the electrodes 27 and 28. Element 47 is provided to isolate the supply of power from circuit 31 to the switches, latches and associated elements, and a reset 48 is arranged to release the latches 41 and 42.

Referring now to Figure 5, there is shown a schematic circuit diagram for the block diagram shown in Figure 4, and the operation of this circuit will now briefly be described. Supply is drawn from a battery to be topped-up via two leads (not shown) respectively connected through fuses e1 and e2 to a diode bridge n1. The polarity of connection of the leads accordingly does not matter, because the bridge n1 always supplies power to the remainder of the circuit with the correct polarity, through a potential limiting circuit including transistors Tr1 and Tr2, and Zener diode Z1. Should the voltage rise above the maximum safe voltage, relay dl drops out, disconnecting power from the remainder of the circuit through contact d1/1. Provided that the potential supply is not too high, lamp h1 is illuminated to indicate that the circuit is correctly powered.The pump 32 is shown by motor ml, operable by means of a manual push-button switch b1 (switch 34, Figure 4) in series with relay contact d4/2. Relay d4 is energised to change over contact d4/2, so that an audible warning device h5 is energised instead of the motor ml if switch b 1 is not released once liquid has contacted the upper electrode 27.

Power is supplied to thr remainder of the circuitry through a DC/DC converter 47, which serves to isolate from the bridge n 1 the power supplied to the probe 22 and the associated detector circuit. As will be appreciated from a consideration of the schematic circuit diagram, if no connection is made between electrode 28 and the probe common (tube 25), lamps h2 and h3 (indicators 40 and 39, Figure 4) are illuminated, If only the electrode 27 is not contacted by liquid, only lamp h3 is illuminated. Depressing switch bl (switch 34) energises the pump until the liquid level rises to contact electrode 27, turning on transistor Tr4 to energise relay d4. This illuminates lamp h4, indicating a cell is full, and also energises the audible warning device h5 until switch bl is released. Switches b3 and b4 correspond to the test switches 46 and 45 respectively of Figure 4, and switches b2/1, b2/2 and b2/3 constitute the reset 48.

As will be appreciated from the foregoing, the apparatus of this invention allows the topping-up of the cells of a wet battery installation in a simple and reliable manner. A cell cannot be overfilled and moreover an operator is given a clear indication if the electrolyte level in a cell is below the minimum allowable level, showing possibly that a cell is fauity. If several cells are below the minimum allowable level, an operator is informed that too long intervals are being left between topping-up operations.

Claims (12)

Claims

1. Apparatus for dispensing a liquid, which apparatus comprises a frame adapted for mounting a container of the liquid to be dispensed, an electrically-operated pump means supported by the frame and arranged for pumping liquid from a mounted container, a dispensing probe connected by a flexible hose to a liquid outlet of the pump means, there being at least one electrode arranged on the probe spaced from the free end thereof, and a detector circuit in electrical connection with the electrode and arranged to sense whether or not the electrode contacts liquid in a vessel when the probe has been inserted into the vessel to a predetermined position, the detector circuit serving to inhibit the operation of the pump means when the elctrode is contacted by liquid in the vessel.

2. Apparatus as claimed in claim 1, wherein the probe is provided with a datum referencing means to allow the probe to be inserted into a vessel to a predetermined position.

3. Apparatus as claimed in claim 2, wherein the datum referencing means comprises an abutment shoulder for engaging with a wall of the vessel defining an opening through which the probe is inserted.

4. Apparatus as claimed in any of the preceding claims, wherein a second electrode is provided on the probe, nearer the free end of the probe than the first-mentioned electrode, the second electrode also being electrically connected to the detector circuit, such that the detector circuit may give an indication if the liquid level is below the second electrode.

5. Apparatus as claimed in claim 4, wherein the detector circuit is arranged to give an indication if the second electrode does not contact liquid, a different indication if the second electrode contacts liquid but the first-mentioned electrode does not, and to inhibit operation of the pump means if the first-mentioned electrode contacts liquid.

6. Apparatus as claimed in any of the preceding claims, wherein the free end of the liquid-dispensing part of the probe is conductive so as to constitute a further electrode with which a circuit including at least the first-mentioned electrode may be completed, and detected by the detector circuit.

7. Apparatus as claimed in any of the preceding claims, wherein the detector circuit is provided with means for connecting the detector circuit to a cell or cells of a battery the electrolyte of which is to have liquid dispensed thereto, whereby the detector circuit may draw power from the cell or cells.

8. Apparatus as claimed in claim 7, wherein the detector circuit includes a power supply unit having a DC/DC converter, said connecting means supplying power to the converter.

9. Apparatus as claimed in claim 8, wherein the connecting means is wired to the DC/DC converter through a diode bridge network.

10. Apparatus as claimed in any of the preceding claims, wherein the detector circuit includes a control circuit for the pump means, to allow energisation of the pump by manual operation of a switch until the first-mentioned electrode completes a circuit on contacting liquid.

11. Apparatus as claimed in any of the preceding claims, wherein the detector circuit is arranged within a separate control box which is adapted both for carrying on the frame of the apparatus and by an operator also carrying the probe.

12. Apparatus for dispensing a liquid substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings;