Liquid dispensing apparatus

Abstract

For a fluid dispensing system, control apparatus controls the output of the delivery nozzle such that a container is filled to a predetermined level relative to the nozzle without the level detection inaccuracy due to surge of fluid within the container. The control has a circuit in which a bi-stable device is coupled to a detector on the delivery nozzle which is caused to operate when the bi-stable device is in the set condition. Surge merely causes a transient switch to the re-set condition, whereas a given level of fluid relative to the nozzle maintains the re-set condition and terminates fluid flow. Provision for reduced flow between detection of surge and detection of the given level is accomplished through a sequencing circuit.

Description

BACKGROUND OF THE INVENTION

This invention relates to liquid dispensing apparatus and is particularly, although not exclusively, concerned with the kerbside dispensing of petrol in self-service petrol stations.

It is well known to provide automatic nozzles for petrol pumps and other liquid dispensers, which have a cut-off facility to inhibit the further supply of liquid when the level of liquid in a container being filled reaches the end of, or a predetermined position along the nozzle. However, such arrangements do not accommodate the surging that may take place particularly within a filler pipe to a container being filled, so that a false reaction can readily occur with the supply being cut off prior to the complete filling of the container. This is inconvenient as it means that manned initiation of further delivery from the nozzle is necessary with the result that the delivery operation cannot be left un-attended.

The surge characteristics of different containers and their filler pipes or apertures which might need to be filled vary considerably and depend, among other things, upon their shape, the degree to which they have been filled, upon the shape and disposition of the filler pipe or aperture into which the nozzle is inserted and upon the flow rate of the liquid from the nozzle. Consequently the degree of falsity of the result when using such known automatic nozzles can vary considerably from one container to another, with the consequence that it cannot be overcome for example by the automatic passage of a further fixed quantity of liquid following operation of the cut off.

It is therefore an object of the present invention to provide an improved control means for a liquid dispensing system incorporating an automatic nozzle, which alleviates these disadvantages and permits substantially complete filling of any container with an automatic final cut-off of the liquid supply, while allowing for intervening surges.

SUMMARY OF THE INVENTION

Accordingly the present invention provides control apparatus for a liquid dispensing system including a pump and a delivery nozzle, comprising a detector arranged on the nozzle to be unaffected by normal delivery through the nozzle but responsive to fluid surge against delivery from the nozzle, and control means arranged to control the delivery of liquid from said pump in response to the detection of fluid surge or liquid rise by the detector.

Preferably said control means is arranged to cause delivery of liquid by the pump at a first flow rate on receipt of a starting signal, to cause delivery at a lower flow rate on receipt of a first signal from said detector, and to terminate delivery on receipt of a second signal from said detector.

Preferably said control means is arranged to cause delivery at a yet lower or dribble rate on receipt of an intermediate signal from said detector spaced in time between said first and second signals.

Preferably said starting signal is provided by means of a switch device associated with and operable by a trigger provided on said nozzle.

According to a further aspect of the present invention, there is provided a liquid dispensing apparatus including the control apparatus of any one of the previous four paragraphs.

BRIEF DESCRIPTION OF DRAWINGS

In order to promote a fuller understanding of the above, and other, aspects of the invention two embodiments will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 shows diagrammatically the application of the embodiments of the invention to a petrol dispensing unit,

FIG. 2 illustrates diagrammatically a detector a discriminator and a sequence control means for the first embodiments, and

FIG. 3 is a graphical representation of some of the signals involved in the operation of the first embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

The embodiment of the invention now to be described is incorporated in a liquid dispensing apparatus as shown in FIG. 1, for dispensing from a liquid reservoir 10, comprising a pump/metering system shown in block form at 11 arranged to feed and meter liquid from the reservoir through a flexible hose 12 to a dispensing nozzle 13 which may incorporate a one way valve (not shown) in known manner per se. The nozzle includes a trigger or handle 14 by which the user can cause delivery from the nozzle. The pump/metering system 11 is of a type which may be arranged to delivery liquid at a number of selectable flow rates, the selection being achieved by the provision of an electrical signal on a selected one of a corresponding number of inputs to a controller associated with the pump/metering system. An example of such a pump/metering may be found in that disclosed and claimed in the Complete Specification of my co-pending British Pat. application No. 1454/71. The means provided in that pump/metering system for controlling the rate of delivery may be readily adapted in known manner per se, to be responsive to an electrical signal on one of for example three inputs, 15, 16, 17 in FIG. 1, to give a selection from three possible rates of supply by the pump/metering system 11. Further when no signal is applied to any of the inputs then it may be arranged that delivery ceases.

In the first embodiment of the invention, a first detector 20 is arranged on the nozzle 13 towards the outlet end thereof. The detector 20 is of a suitable type known per se which will give an electrical output signal when contacted by the liquid to be dispensed or when it experiences a surge of fluid pressure as a result of a transient or long term rise of liquid against delivery from the nozzle. The detector 20 is preferably positioned on outside of the nozzle so as to be unaffected by the flow of liquid through the nozzle during normal delivery, but so that it will give an indication if the liquid being delivered rises for instance in the filler pipe 18 of a container 19 to be filled, either as a result of a surge in the filler pipe 18 or the container 20 becoming filled and the liquid reaching the level of the detector against the delivery flow, such indication being either as a result of liquid contact or of fluid pressure surge.

A switch device 21 is arranged on the hose cock to be operable by the handle 14 when it is moved to cause delivery of liquid from the nozzle.

A control unit 22 is provided and has inputs connected to receive signals from the detector 20 and the switch device 21 respectively. The control unit has apart from power supply and like connections which are not shown, three out-puts connected respectively to the inputs 15, 16 and 17 of the pump/metering system 11.

The arrangement of the control unit 22 is shown in more detail in diagrammatic form in FIG. 3, and it can be seen to comprise an input circuit 30 which is connected to the switch device 21 to receive signals therefrom and transmit them to a bistable switch circuit 31 to trigger it into a "set" condition on the receipt of each such signal, assuming it is not already in the set condition.

The bistable switch circuit 31 is connected with a four stage shift register 32 so that on being triggered to its set condition, it applies a pulse to shift the register through one stage. The bistable switch circuit 31 is also connected to one input of each of three dual input AND gates 33, 34 and 35 so as to raise these inputs when in its set condition. The outputs of the last three stages of the shift register 32 are connected respectively to the second inputs of the AND gates 33, 34 and 35, so that the state of the shift register determines which one of the AND gates is open to give an output signal on one of the outputs 36, 37 or 38. The output first stage of the shift register is not connected thus to give a reset condition of the register with no output from any of the AND gates.

The outputs 36, 37 and 38 are connected respectively to the inputs 15, 16 and 17 of the pump/metering system so that when a signal occurs on them they produce respectively a normal liquid delivery rate, a lower delivery rate and a yet lower or "dribble" delivery rate.

The control unit 22 further comprises a second input circuit 40 connected to the detector 20 to receive signals therefrom and transmit them by way of an inverter circuit 41 to one input of a dual input AND gate 42, to a delay circuit 44, to one input of a further dual input AND gate 43, and to the bistable switch circuit 31 in such manner as to trigger it out of its "set" condition into a "reset" condition, on detection of the presence of liquid. The delay circuit 44 has two outputs arranged respectively to transmit, after a predetermined delay, signals from the detector 20 to the other inputs of the AND gates 42 and 43. The output of the AND gate 43 is connected to the shift register 32 in such manner that an output from the gate 43 resets the shift register to its initial or first condition with no output on any of the lines 36, 37 or 38. The operation of the apparatus of FIG. 1 may now be described with the assistance of FIG. 3. In FIG. 3 there are shown four horizontal time axes A, B, C and F. The signals from the switching device 21, the detector 20, and the time delay circuit 44 are shown respectively on the axes A, B and D; whereas the flow rate of delivery of liquid from the nozzle 13 is shown on the axis F.

On lifting of the handle 14 to open the hose cock, the switch 21 produces a signal A1 and causes the bistable switch 31 to trigger into its set condition. This causes the shift register 32 to be triggered to its second stage from its reset initial condition and thus a signal is produced on the output 36 of AND gate 33 to cause initially a normal rate F1 of liquid delivery by the pump/metering system 11 through the nozzle 13.

If a surge or other event occurs the detector 20 produces a signal B1 at a time t.sub.1 such signal continuing while liquid contacts the detector 20. The bistable switch 31 is caused by the leading edge of that signal to trigger back to its reset condition thus inhibiting all the AND gates 33, 34 and 35, and particularly the gate 33, to cut off the delivery of liquid by the pump/metering system 11 at flow rate F1 at the point t.sub.1 in time.

When the detector 20 no longer experiences the liquid or fluid pressure, i.e., when the surge has receded assuming it was a surge, the signal B1 returns to its normal level. However, on the receipt of the signal B1, the time delay circuit 44 was initiated and after a chosen time, which is set to be sufficient for any anticipated surge to have receded, transmits, at the point t.sub.2 in time, a signal C1 to the AND gates 42 and 43. Since the detector 20 is no longer giving an output, and the inverter 41 is between it and the gate 42, the gate 42 will then have signals on both its inputs, and will therefore open to trigger the bistable switch 31 to its set condition. When this happens the shift register 32 is moved on to its third condition and AND gate 34 is opened to cause delivery at a reduced flow rate, F.sub.2, by the pump/metering system 11 as a result of an output signal on the line 37.

It will be noted that since the AND gate 43 which receives a signal direct from the input circuit 40 without inversion, has in that circumstance a signal on only one of its two inputs, it will not be opened and the shift register 32 will not be affected thereby.

If when the delay circuit delivers the signal C1, the detector 20 was still experiencing liquid contact or pressure surge, as may be the case if the tank had filled rather than the occurence of a surge or the surge was of such magnitude that it was not safe to leave to automatic control, then the complementary situation results. The gate 42 is not opened so that the pump/metering unit does not re-commence delivery, and the gate 43 is opened to reset the shift register 32 to its initial position so that manuel operation of the handle 14 on a subsequent occasion initiates normal delivery as above.

On the other hand delivery is continued at the lower rate discussed above, and a second surge or other event occurs, the process is repeated as described above with signals B2, C2, at times t.sub.3 and t.sub.4 respectively, and flow rate F3 which is yet lower and may be such as to be termed a "dribble" rate for final topping up of the tank. Again if detection of liquid persists and signal B2 continues until the occurence of signal C2, then the delivery is stopped and the shift register reset.

If delivery does continue at flow rate F3, it being anticipated that this is so low that surges cannot occur, the next occurrence at time t.sub.5 of a signal (B3) from the detector 20 will in fact be when the container is full. Thus when the delay circuit provides signal C3 at time t.sub.6, the routine discussed above applies and the pump/metering device is shut off by the shift register 32 being reset.

Thus it can be seen that the apparatus provides for the automatic control of the delivery of liquid from the nozzle to cater for surges in the filler and completion of the filling of the container. It can be seen further that the arrangement of input circuit 40, gates 42 and 43 and delay circuit 44 form a discriminator means for determining whether the detector 20 has experienced a surge of a full container. The shift register 32 to-gether with the bistable switch 31 form a sequencing means for the control of the pump/metering device and sequencing of the flow rates delivered thereby.

In a second embodiment the detector 20 is supplemented by a second similar detector 50 which is similarly arranged on the nozzle but higher up from the outlet. The detector 50 is provided primarily to detect when the container being filled is full. The output of the detector 50 is connected to the control means 22 which is generally similar for this embodiment to that for the previous embodiment. However for this embodiment the AND gate 43 may be dispensed with, and the output of the detector 50 is arranged to trigger the bistable switch 31 into its reset state and to re-set the shift register 32 to its initial state directly on detection of liquid on completion of filling.

It will be appreciated that in either embodiment, the shift register 32 may be replaced with any suitable multi-state circuit such as a binary or decade counter with suitable output coding gates to give the equivalent of the outputs 33, 34 and 35 for its successive states following an initial state. Further it will be appreciated that the circuit may be arranged to give only one flow rate or more than two successively lower flow rates between the normal flow rate and final cut-off of delivery. Such selection is readily made by the choice of the number of states that the shift register or counter has.

Claims

What I claim is:

1. Control apparatus for a liquid dispensing system including flow regulating means and a delivery nozzle, comprising a first detector arranged on the nozzle to be unaffected by the normal liquid delivery through the nozzle but responsive to fluid surge against delivery from the nozzle, and control means operably connected to control said flow regulating means in response to the detection of a surge by the first detector, wherein said control means is electrically operated and comprises a bi-stable switch circuit connected to be triggered into a set condition on receipt of an electrical starting signal and to be triggered into a re-set condition on receipt of an electrical signal from said first detector on detection of a surge thereby, and connected to cause said flow regulating means to operate when in said set condition.

2. Control apparatus according to claim 1 including a second detector arranged on said nozzle to be unaffected by the normal delivery of liquid through the nozzle but responsive to fluid surge against delivery from the nozzle, said second detector being positioned further from the outlet of the nozzle than said first and operably connected to said control means whereby to inhibit delivery of liquid from the flow regulation means in response to the detection of a surge thereby.

3. Control apparatus according to claim 1, wherein said control means is arranged to cause delivery of liquid by the pump at a first flow rate on receipt of said starting signal, and to cause delivery at a second flow rate lower than said first on receipt of a first signal from said first detector.

4. Control apparatus according to claim 3, wherein said control means is further arranged to cause delivery of liquid by the flow regulating means at a third flow rate lower than said second on receipt of an intermediate signal from said first detector spaced in time between said first and second signals.

5. Control apparatus according to claim 1, wherein said starting signal is provided by operation of a trigger on said nozzle.

6. Control apparatus according to claim 1, wherein said control means further comprises sequencing means in the form of a counter circuit having at least two sequential states, and an output associated with each of those states following an initial state, the bi-stable circuit being arranged to trigger the counter through one state each time it is itself triggered to its set condition, and wherein each said output of the counter circuit is arranged to be operatively connected to said flow regulation means to cause it to deliver liquid in response to an output signal thereon at a rate associated with that output.

7. Control apparatus according to claim 6, wherein each said counter circuit output includes an AND gate arranged to be opened by said bi-stable circuit when in its set condition.

8. Control apparatus according to claim 6, wherein said counter circuit is in the form of a shift register.

9. Control apparatus according to claim 1, wherein said control means further comprises discriminator means arranged to distinguish between a transient signal from said first detector caused by a surge against delivery and a constant signal caused by static level of liquid in a container being filled on completion of delivery.

10. Control apparatus according to claim 1, wherein said control means further comprises an input circuit to receive signals from said first detector, the input circuit having a first output connected to trigger said bi-stable switch into its re-set condition on receipt of a signal from the first detector, a second output connected by way of a time delay circuit to one input of a dual input AND gate, and a third output connected by way of an inverter circuit to the second input of said dual input AND gate, the output of said dual input AND gate being connected to said bi-stable switch circuit whereby to trigger it into its set condition on the occurrence of a signal from said first detector of shorter length than the delay period of said time delay circuit.

11. Control apparatus according to claim 6, wherein said input circuit has a fourth output connected to one input of a further dual input AND gate, and said time delay circuit has a second output connected to the other input of said further dual input AND gate the output of which is connected to said initial state on the occurrence of a signal from said first detector of greater length than the delay period of said time delay circuit.

12. Control apparatus for a liquid dispensing system including flow regulating means and a delivery nozzle, comprising a first detector arranged on the nozzle, to be unaffected by the normal liquid delivery through the nozzle but responsive to fluid surge against delivery from the nozzle, and control means operably connected to control said flow regulating means in response to the detection of a surge by the first detector, including a second detector arranged on said nozzle to be unaffected by the normal delivery of liquid through the nozzle but responsive to fluid surge against delivery from the nozzle, said second detector being positioned further from the outlet of the nozzle than said first and operably connected to said control means whereby to inhibit delivery of liquid from the flow regulating means in response to the detection of a surge thereby, wherein said control means is electrically operated and comprises a bi-stable switch connected to be triggered into a set condition on receipt of an electrical starting signal and to be triggered into a re-set condition on receipt of an electrical signal from said first detector on detection of a surge thereby, and connected to cause said flow regulating means to operate when in said set condition, and sequencing means in the form of a counter circuit having at least two sequential states, and an output associated with each of those states following an initial state, the bistable circuit being arranged to trigger the counter through one state each time it is itself triggered to its set condition, each output of the counter circuit being arranged to be operatively connected to said flow regulating means to cause it to deliver liquid in response to an output signal thereon at a rate associated with that output, and said second detector being connected to said counter circuit whereby to set it to said initial state on the detection of a surge thereby.