FIELD

The present disclosure relates to a fluid level gauge apparatus for providing information on a level of a liquid within a container. The disclosure relates especially, but not exclusively, to a fluid level gauge apparatus for displaying and providing an output in relation to a measured level of a liquefied gas within an enclosed pressurised tank or cylinder.

BACKGROUND

There are many residential, commercial and transport appliances for gases which are stored in a pressurised tank or cylinder. These gasses include hydrocarbon gases, such as LPG, butane, and propane. Typically, the gas is stored within the tank under pressure in a liquid form, wherein as the vapour is released through a valve, the liquid within the tank changes into a gaseous form.

Since the tank or cylinder must be sealed to inhibit the escape of the gas, the measuring of the volume of liquefied gas remining within the container must be done without breaking the pressurised seal. In one type of measuring apparatus, a float gauge is positioned within the tank, and is magnetically coupled to a liquid level gauge positioned on an exterior of the tank. The float gauge includes a movable pivot arm having a float at one end, which rises and falls with the level of the liquid within the tank. The opposite end of the movable pivot arm includes a pinion gear that turns a gear on a shaft of the float gauge, which in turn causes a dial of the liquid level gauge to move, by way of co-operating magnets. This thereby provides a visual indication as to the level of fluid within the tank. U.S. Patent No. 7,219,546 to Rochester Gauges, LLC., illustrates one form of a gear and drive shaft assembly for a conventional float gauge.

The shaft is typically connected to tank magnets which are magnetically coupled to receiving magnets of the liquid level gauge. Thereby, as the shaft and connected tank magnets rotate, the magnetic flux rotates the receiving magnets which moves the external visual indicator, such as a needle or dial. The use of magnetic coupling facilitates maintaining the integrity of the tank seal by allowing the tank magnets in the sealed interior of the tank to move the receiving magnets, which are outside the sealed interior of the tank, without requiring a direct physical connection. The liquid level gauge is typically detachable from the outer surface of the tank, which means if there is a problem, the liquid level gauge can be replaced without emptying the tank. Examples of such gauges are disclosed in U.S. Patent No’s. 6,089,086 and 6,041,650 both to Rochester Gauges, LLC. The use of magnets is not exclusive to Rochester Gauges, LLC., and this type of system has been used since the early 1900’s, as illustrated in U.S. Patent 1,448,842 (Gregory) having a priority date in the 1920’s, and U.S. Patent 2,311,387 (Hastings) and U.S. Patent 2,578,104 (Taylor) both having priority dates in 1940’s.

Some liquid level gauges provide both a visual indication as to the volume of fluid within the tank, as well as an analogue output signal, such as a variable output voltage, which can be used to remotely monitor the tank level. Many conventional liquid level gauges are however susceptible to temperature variations, which may affect their output. In the case of liquid level gauges includes a resistive type sender, the mechanical nature of the switching contact can also lead to problems. Furthermore, a potential difference must be generated across an electrical conductor which reduces the lifespan of the assembly and/or requires a relatively large battery.

The term “liquid level gauge”, as used herein (and as against the float gauge, or the apparatus including the float gauge) refers to the part, external to the tank interior, which provides a visual indication and/or analogue output signal indicative of the liquid level and which is sometimes referred to as an indicator dial assembly or gauge head. For the purposes of the present disclosure the liquid level gauges discussed above are examples of fluid level gauge apparatuses.

It should be appreciated that any discussion of the prior art throughout the specification is included solely for the purpose of providing a context for the present disclosure and should in no way be considered as an admission that such prior art was widely known or formed part of the common general knowledge in the field as it existed before the priority date of the application.

The phrase “optical sensor” used throughout the specification and claims should be given it broadest definition and includes any type of photo emitter/receiver, photodetector, photosensor or may comprise a separate emitter and a receiver. The terms “fluid” and “liquid” are used interchangeably throughout the specification.

SUMMARY

It would be desirable to provide a fluid level gauge which overcomes or mitigates at least some of the aforementioned problems, or at least provides the public with a useful alternative. Various aspects of the present disclosure, and/or embodiments thereof, may provide one or more of the above desired outcomes. According to a first aspect of the present disclosure, there is provided a fluid level gauge apparatus for an enclosed container, comprising: a linking member couplable to an internal gauge retained, at least partly, within said enclosed container; a gradient member; and an optical sensor for measuring light received from the gradient member; wherein the fluid level gauge apparatus is configured so that movement of the linking member by its coupling to the internal gauge causes relative movement of the optical sensor and the gradient member; wherein light received by the optical sensor from the gradient member varies according to the relative positions of the optical sensor and the gradient member; and wherein the optical sensor measures light received from the gradient member to thereby generate an output signal relating to the fluid level within the enclosed container.

In an embodiment the fluid level gauge apparatus further comprises a visual indication member connected or in communication with the linking member, to thereby provide a visual indication of the fluid level within the tank.

The visual indication member may comprise a needle that is configured to move relative to display markings to visually indicate the fluid level within the enclosed container.

The display markings may be digits indicating the volume percentage of fluid within the enclosed container.

The display markings may be a coloured disk indicating the level of the fluid within the enclosed container.

In an embodiment the relative movement of the optical sensor and the gradient member is arranged to replicate the movement of the internal gauge

The internal gauge may be a float gauge including a float driven sensor arm. In one form the float gauge may include a movable pivot arm having a float at one end, which rises and falls with the level of the liquid within the enclosed container. The opposite end of the movable pivot arm may include a pinion gear that turns a gear on a shaft of the float gauge, which in turn causes the needle via a magnetic coupling, to move thereby visually indicate the fluid level within the enclosed container.

The movable gradient member may be rotatable or slidable relative to a generally fixed optical sensor. The liquid within the enclosed container may be liquefied gas such as LPG, propane, butane, hydrogen or other gaseous liquid fuel, that is held in a pressurised state. The enclosed container may be a cylinder, tank or other type of pressurised vessel.

In an embodiment the fluid level gauge apparatus is magnetically couplable to the float level assembly retained at least partly within the enclosed container, wherein the fluid level gauge can be removed or replaced without having to empty the enclosed container.

In an embodiment the gradient member is configured such that different parts of a gradient arrangement of the gradient member have different optical characteristics, so that in use, light received by the optical sensor from the gradient arrangement is dependent upon the part of the gradient arrangement to which the optical sensor is directed.

Thus, in use, one of more characteristics or features sensed by the optical sensor by virtue of light received by the optical sensor from the gradient member, varies according to the relative positions of the optical sensor and the gradient member.

In an embodiment the one or more optical characteristics vary at least somewhat proportionally to the difference in relative positions from an initial predetermined position.

For example, in an embodiment the gradient arrangement may vary from a relatively less optically reflective (or transmissive) first region to a relatively more optically reflective (or transmissive) second region, with a continuous or stepped progression in reflectivity between the first and second regions.

An advantage of using a gradient arrangement in which the optical characteristic varies at least somewhat proportionally to the difference in relative positions from an initial predetermined position, is that this may facilitate an output of the sensor having a somewhat direct relationship to the relative positions of the optical sensor and gradient member.

However, it is not necessary that there be any sequential progression in the nature of the optical characteristic, provided at sequential regions of the gradient arrangement. It is sufficient that different regions of the gradient arrangement result in different outputs (e.g. readings or data) from the optical sensor, which can be used (for example via additional analysis) to determine fluid level in the container. By way of nonlimiting example, different regions of the gradient arrangement may preferentially reflect (or transmit) different colours. The colour of light detected by the optical sensor at a given time can used to provide a measure of fluid level in the container. The specific colours used, and the order of the colours in the gradient arrangement, can be selected as desired or convenient, and is not critical to this approach to measurement, provided the relationship between each detected colour and the fluid level is known. In another example, in which the optical sensor can differentiate between different symbols (for example, where a small camera is used) the gradient arrangement may comprise different symbols at different regions thereof. Again, the arrangement of symbols may be proportional to position, for example use of the symbol numeral ‘9’ at the part of the gradient arrangement read by the optical sensor when the fluid container level is highest, use of the symbol numeral at the part of the gradient arrangement read by the optical sensor when the fluid container level is substantially empty, and with sequential symbols numerals 8, 7, 6, 5, 4, 3, 2, in order, in intermediate regions, or but does not need to be proportional, for example different regions of the gradient arrangement may be provided with any different, distinguishable, symbols, which can then be used to make a measure of fluid level.

In an embodiment the gradient member has a surface with a colour or pattern gradient thereon.

The colour or pattern gradient may be selected from a group including, but not limited to, a greyscale gradient, a coloured gradient, or markings, such as but not limited to a patterned gradient, a cross hatching gradient, a gradient formed by dots, dashes, pixels or another indicium. The gradient may range from a relatively highly reflective region to a substantially less reflective region. The gradient may range from a light colour or minimal/no markings, to a dark colour or concentrated markings.

The optical sensor may operate in the visible light part of the electromagnetic spectrum. The optical sensor may operate in one or more non-visible parts of the electromagnetic spectrum. The optical sensor may operate one or more different parts of the spectrum. The optical sensor may comprise an emitter and a detector, and may, for example, comprise an infrared emitter and detector. The optical sensor may comprise an infrared emitter and detector for measuring light received from the gradient member.

In an embodiment the fluid level gauge apparatus comprises a housing having a base, which is attachable to an upper cover, to thereby form a primary chamber.

In an embodiment the base and upper cover are opaque, so that light is inhibited from entering the primary chamber. In an embodiment the primary chamber retains the gradient member therein and the upper cover includes an aperture, through which the optical sensor is configured to extend, such that it is positionable adjacent the gradient member.

The fluid level gauge may further include a transparent lid that is connectable to the upper cover to thereby form a secondary chamber which retains a visual indication member. The secondary chamber may include a visual level label or indicia.

The base may be attached to the upper cover by way of ultrasonic welding, gluing or other fixing means.

The optical sensor may be part of a plug that is configured to engage the aperture in the upper cover, and may frictionally engage, or be connected by way of a clip, bayonet fitting, or cooperating threaded portions. In another form the optical sensor is hardwired to the housing and may be welded, glued or otherwise affixed thereto.

In an embodiment the gradient member is moveable by said internal tank sensor via said linking member.

In an embodiment the linking member comprises a retaining portion for the one or more magnetic coupling members which are magnetically couplable to the float level assembly retained at least partly within the enclosed container.

In an embodiment the gradient member and the linking member are mutually connected such that in use they move substantially as a single unit.

In an embodiment the gradient member and the linking member are formed as a single component.

In an embodiment the fluid level gauge apparatus comprises a visual indication member connected or in communication with the movable gradient member, to thereby provide a visual indication of the fluid level within the tank.

In an embodiment the gradient member is rotatable.

In an embodiment the gradient member comprises a rotatable disk frame member.

The gradient member may include a central portion for engaging a spine upwardly extending from the base. In an embodiment the gradient member is supported relative to the housing by a bearing arrangement, to thereby permit rotation of the gradient member.

In an embodiment the gradient member is supported on a ball bearing which is positioned on the top of the spine, to thereby permit rotation of the disk frame member.

The central portion may also include a retaining portion for one or more magnetic coupling members which are magnetically couplable to the float level assembly retained at least partly within the enclosed container.

In an embodiment the retaining portion is in the form of a plurality of spaced apart passageways for holding magnets therein.

In an embodiment the retaining portion is in the form of two spaced apart passageways for holding cylindrical magnets therein.

The central portion may include an upwardly extending protrusion central thereof and configured to extend through a central opening in the upper cover and into the secondary chamber, wherein the needle is attached to a top of the protrusion. The reader will appreciate that the spine of the base and the protrusion of the central portion coaxially align.

The gradient member may further include an annular flange attached to and extending around the central portion and configured to receive a colour or pattern gradient/gradient reflector thereon, which may be in the form of a label or may be printing directly onto the annular flange.

The gradient member and/or underside of the upper cover may include light shields to inhibit light entering the primary chamber between the edge of the central opening and protrusion of the disk frame member. The reader would appreciate that light entering the primary chamber may affect the operation of the optical sensor. Seals and other light inhibiting means may also be used to minimise the light entering the primary chamber. The light shields may be in the form of hollow cylinders, which may be substantially coaxial.

The housing may further contain an electronics chamber for retaining loT chips, circuit boards (PCB), transmitters, communication means, or other electronic devices.

In an embodiment, the optical sensor produces an analogue output, in the form of an output voltage, based on the gradient scale, wherein a change in the gradient results in a varying of the output voltage. This provides a low voltage system for monitoring and displaying the level of fluid within the container. Therefore, by detecting or sensing the varying amount of light reflected from/via a rotating or revolving gradient scale reflector into an optical detector, a varying analogue output range can be generated to thereby indicate the level of the fluid within the container.

The movable gradient member in a preferred form is a disc or annular member that is configured to rotate around a central axis. The optical sensor is offset from the central axis of the disc and adjacent a surface thereof, in that as the disc rotates the optical sensor is able to measure the colour or pattern gradient as it changes.

In an embodiment, the gradient member is able to rotate through 360 degrees, which means that it accurately reads the level within the tank, even when the tank is full and the fluid level gauge apparatus is attached. This is in contrast to conventional gauges, where the needle moves between stops, which can result in a false reading when attached to the tank in situ due to misalignment of the co-operating magnets.

Alternatively, the movable gradient member is elongate having a gradient that changes from a first end to a second end. The optical sensor is positioned adjacent a surface of the elongate movable gradient member, in that as it moves along the elongate member, it is able to measure the colour or pattern as it changes.

According to a second aspect of the present disclosure there is provided a fluid level gauge apparatus for a tank, the fluid level gauge apparatus having a gradient reflector and an optical sensor, which can be moved relative to each other, the fluid level gauge being adapted to be magnetically coupled to an internal tank sensor for providing information on a level of fluid within the tank.

In an embodiment the gradient reflector is moveable by said internal tank sensor.

In an embodiment the optical sensor remains substantially stationary relative to the fluid level gauge apparatus as a whole, in use.

In an embodiment the optical sensor is moveable, by said internal tank sensor.

In an embodiment the gradient reflector remains substantially stationary relative to the fluid level gauge apparatus as a whole, in use.

In an embodiment the gradient reflector (or gradient scale) varies the amount of light reflected into a detector of the optical sensor dependent upon the relative position determined by said internal tank sensor. In an embodiment an output of the detector to changes according to the variation of the amount of light reflected.

In an embodiment said output of the detector is indicative of the level of fluid within the tank.

In an embodiment the level of fluid within the tank can be calculated by analysis of the output of the detector.

In an embodiment the level of fluid within the tank can be calculated by electrical/electronic analysis of the output of the detector.

In an embodiment the relative movement of the gradient reflector an optical sensor is rotational.

In an embodiment the angle of rotation can be determined via further electrical/electronic analysis, to thereby calculate the level of fluid within the tank.

According to another aspect of the present disclosure there is provided a fluid level gauge apparatus for an enclosed container, including: a linking member couplable to an internal gauge retained, at least partly, within the enclosed container; a movable gradient member being configured to replicate the movement of the internal gauge, the gradient member having a surface with a colour or pattern gradient thereon; an optical sensor for measuring a reflection from the colour or pattern gradient to thereby generate an output signal relating to the fluid level within the tank; and a visual indication member connected or in communication with the movable gradient member, to thereby provide a visual indication of the fluid level within the tank.

According to another aspect of the present disclosure there is provided a method of providing data on a volume of liquefied gas within a sealed container, including the steps of: positioning a float sensor assembly at least partly within the sealed container, the float sensor assembly including a movable float and at least one tank magnet; providing a fluid level gauge including a visual display, a gradient member, having indicia thereon, an optical sensor configured to measure light received from the gradient member, and at least one magnet, the gradient member and optical sensor being movable relative to each other; magnetically coupling the fluid level gauge to the float sensor assembly, adjacent the at least one tank magnet; and permitting the gradient member or optical sensor to move based on movement of the float of the float sensor assembly, wherein the optical sensor provide an output indicating the volume of liquefied gas within the sealed container, and the visual display providing a visual indication of the volume of liquefied gas within the sealed container.

In an embodiment the optical sensor is configured to measure a reflection from the gradient member.

The output of the optical sensor may be an analogue electrical signal.

It should be appreciated that features of embodiments, or optional features, set out above in relation to any of the above aspects may be incorporated into any of the other embodiments unless logic dictates otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate, by way of example only, embodiments in accordance with the present disclosure and, together with the description and claims, serve to explain the advantages and principles thereof. In the drawings,

Figure 1 is a schematic view of a gas cylinder with an embodiment of a fluid level gauge apparatus in accordance with the present disclosure magnetically coupled to a float sensor assembly; Figure 2 is a front perspective view of the fluid level gauge apparatus of Figure 1 ; Figure 3 is a side perspective view of the fluid level gauge apparatus of Figure 2 with transparent lid attached;

Figure 4 is another front perspective view of the fluid level gauge apparatus of Figure 2; Figure 5 is an underside perspective view of the fluid level gauge apparatus of Figure 2; Figure 6 is a top view of the fluid level gauge apparatus of Figure 2; Figure 7 is an exploded view of the fluid level gauge apparatus of Figure 3; Figure 8 is an exploded view of the fluid level gauge apparatus of Figure 3, showing the ball bearing and a greyscale gradient;

Figure 9 is a cross-sectional view through A-A of Figure 4; Figure 10 is a cross-sectional view through B-B of Figure 3; Figure 11 is a perspective view of one embodiment of the gradient member including a gradient pattern, illustrating the position of the optical sensor;

Figure 12 is an exploded view of the gradient member and optical sensor of Figure 11 , with the gradient pattern removed;

Figure 13 is a side view of the gradient member and optical sensor of Figure 11 ; Figure 14 is a top view of the gradient member and optical sensor of Figure 11 , illustrating the gradient member in a first position;

Figure 15 is a top view of the gradient member and optical sensor of Figure 14, illustrating the gradient member in a second position;

Figure 16 is a top view of the gradient member and optical sensor of Figure 14, illustrating the gradient member in a third position;

Figure 17 is a top partial view of the fluid level gauge apparatus of Figure 2, illustrating the movement of the needle as the gradient member rotates into a first position, as shown in Figure 14;

Figure 18 is a top partial view of the fluid level gauge apparatus of Figure 2, illustrating the position of the needle when the gradient member is in a second position, as shown in Figure 15;

Figure 19 is a top partial view of the fluid level gauge apparatus of Figure 2, illustrating the position of the needle when the gradient member is in a third position, as shown in Figure 16;

Figure 20 is a top view of the gradient member illustrating a second embodiment of the gradient pattern;

Figure 21 is a top view of the gradient member illustrating a greyscale gradient; Figure 22 is a rear perspective view of an alternative embodiment of a fluid level gauge; Figure 23 is a side perspective view of the fluid level gauge apparatus of Figure 22 with transparent lid attached;

Figure 24 is another perspective view of the fluid level gauge apparatus of Figure 22;

Figure 25 is an underside perspective view of the fluid level gauge apparatus of Figure 22

Figure 26 is a top view of the fluid level gauge apparatus of Figure 22; Figure 27 is an exploded view of the fluid level gauge apparatus of Figure 22;

Figure 28 is an exploded view of the fluid level gauge apparatus of Figure 22, showing indicia on the dial;

Figure 29 is a vertical medial cross-sectional view of the fluid level gauge apparatus of Figure 22;

Figure 30 is a further vertical medial cross-sectional view of the fluid level gauge apparatus of Figure 22; and

Figure 31 is a schematic view, illustrating a fluid level gauge in accordance with the present disclosure provided with telemetry for communicating with a monitoring station.

DETAILED DESCRIPTION OF THE ILLUSTRATED AND EXEMPLIFIED EMBODIMENTS

Similar reference characters indicate corresponding parts throughout the drawings. Dimensions of certain parts shown in the drawings may have been modified and/or exaggerated for the purposes of clarity or illustration.

Referring to the drawings for a more detailed description, there is illustrated a fluid level gauge 10, demonstrating by way of examples, arrangements in which the principles of the present disclosure may be employed.

As illustrated in Figure 1, the fluid level gauge 10 of the present disclosure may be used to measure the volume of a liquefied gas 12 within a tank 14 (or cylinder) having a valve assembly 16. As the reader would appreciate, gas such as liquefied petroleum gas (LPG), are typically stored under pressure within a tank 14. A float sensor assembly or tank gauge 18 is positioned within the tank 14, and generally includes a mount 20 sealably connected through a wall 22 of the tank 14, tank magnets 24 held within the mount 20, a drive shaft 26, and a pivotable float arm 28 with float 30. The pivotable float arm 28 is connected to the drive shaft 26 by way of a gear member 32, as is known in the art.

Accordingly, as the pivoting float arm 28 moves in response to changes in the fluid level 12 within the tank 14, the drive shaft 26 rotates by way of the gear member 32, thereby moving the tank magnets 24. Since the fluid level gauge 10 is magnetically coupled to the tank magnets 24, by way of receiving magnets 34, movement of the float arm 28, results in movement of the needle 36 and a variation in an output signal generated by an optical sensor 38, as will be further discussed. As illustrated in Figure 2, the fluid level gauge 10 includes a housing 40 comprising a base 42, attachable to an upper cover 44 to thereby form a primary chamber, as shown in Figures 9 and 10. Preferably, the base 42 and upper cover 44 are opaque, in that light is inhibited from entering the primary chamber 46. The base 42 includes tabs 48, 50 having standard mounting holes 52 to engage a conventional mount 20. An optical sensor cable 54 and plug 56 are attached through an aperture 58 in the upper cover 44, as best seen in Figures 6 to 8.

Turning back to Figure 2, the needle 36 is movable relative to the display markings 60, which indicate the percentage of fluid 12 remaining within the tank 14.

As illustrated in Figures 3 and 5, the base 42 includes a depending portion 62 into which the receiving magnets 34 extend, for coupling with the tank magnets 24 within the mount 20. Of course, the shape of the base need not include a downwardly depending portion, illustrated as depending portion 62, but can be configured as desired and suitable to fit the shape of the mount with which it is intended for use, and to provide the receiving magnets 34 positioned suitably for coupling with the tank magnets 24. As further illustrated in Figure 3, a transparent lid 64 is connectable to the upper cover 44 to thereby form a secondary chamber 66, as shown in Figure 10.

As illustrated in Figures 7 and 8, in one embodiment, the fluid level gauge 10 includes a rotatable gradient member 68, having a gradient arrangement in the form of a colour or pattern gradient 70 thereon, or attached thereto. For instance, the colour or pattern gradient 70 may be an annular sticker that is applied to the rotatable gradient member 68. It will be appreciated that the gradient member 68, and the pattern gradient, is connected to the receiving magnets 34 and, in this embodiment, rotates as the tank magnets 24 rotate.

The optical sensor 38 is fixed to the upper cover 44 by way of plug 56, and is configured to measure a change in the colour or pattern gradient 70, as the gradient member 68 rotates. That is, as the gradient member 68 rotates, different parts of the colour or pattern gradient 70 are adjacent to the optical sensor 38, so that different amounts of light are reflected into, and received by, the optical sensor 38. Thus, the amount of light received by the optical sensor 38 is indicative of the rotational position of the gradient member 68, and therefore indicative of the position of the tank magnets 24 and float sensor assembly or tank gauge 18 (or, more generally, the internal gauge) and thus of the level of fluid in the container.

As the reader will appreciate the gradient may be a gradual progression for one colour to another, such as from black to white, as illustrated in Figure 8, through a series of grey tones. Alternatively, the gradient may be a stepped pattern, as illustrated in Figure 11, that has a sequence of differently hatched or patterned formats.

As the gradient changes, and the amount of light reflected into, and received by, the optical sensor 38 changes, the optical sensor 38 varies an output, to thereby adjust the signal sent to a processor (not shown). The processor or other computing device may then use the output signal from the optical sensor 38, to determine the level of fluid within the tank 14 to thereby remotely monitor its contents and to assess when the tank 14 needs to be refilled. The optical sensor may operate in the visible light part of the electromagnetic spectrum, or may, for example, comprise an infrared detector or an ultraviolet detector. For the purposes of this specification references to “light” or “optical” should not be considered limiting to in the visible light part of the electromagnetic spectrum. A light source or emitter should be included in order to illuminate the gradient member and provide light to be detected by the optical sensor, for example after reflection from the gradient member. The optical sensor may comprise one or more detectors adapted to detect different wavelengths or colours, and the gradient may comprise segments of different colours (for example, but not limited to, different colours of the visible light part of the electromagnetic spectrum. Although not considered economically desirable, in one alternative the optical sensor may be a camera such as, for example, the type of camera used in mobile phones. Further, the gradient may be a gradient of varying light transmission (although embodiments relying on reflection are likely more practicable and economically viable) in which case the gradient member may be provided between a light source and the sensor, and the detector may detect light transmitted through the gradient member. A gradient member of this type could be provided by applying an non-uniform at least partially non-transparent opaque coating to a transparent or translucent material, for example by printing thereon or by application of a suitable sticker or the like.

The gradient member 68 comprises a rotatable disk frame member 72 having a central portion 74 for engaging a spine 76 upwardly extending from the base 42. The disk frame member 72 is supported on a ball bearing 78, which in use, is located on the top of the spine 76 to thereby permit rotation of the disk frame member 72.

The central portion 74 includes receiving passageways 80 for holding the cylindrical receiving magnets 34 therein. The central portion 74 may be considered a linking member, as it effectively links the moveable gradient member 68 to the float gauge, via magnetic coupling of the receiving magnets 34 (which are, in use, retained in the central portion 74) to the tank magnets 24. The central portion 74 further includes an upwardly extending protrusion 82 central thereof and configured to extend through a central opening 84 in the upper portion 44, whereby the protrusion 82 extends into the secondary chamber 66, as illustrated in Figure 10. The needle 36 is attached to the top of the protrusion 82, wherein as the disk frame member 72 rotates, the needle 36 likewise rotates and moves relative to the display markings 60.

As illustrated in Figure 7, the disk frame member 72 includes an annular flange 86 extending around the central portion 74 and configured to receive the colour or pattern gradient 70 thereon, as illustrated in Figure 8.

Figures 9 and 10 illustrate cross-sectional views through the fluid level gauge 10, with Figure 9 illustrating the device with the transparent lid 64 removed. As shown in Figures 9 and 10, the primary chamber 46 retains the gradient member 68, which in this embodiment is configured to reflect light emitted by the optical sensor 38, such that the optical sensor 38 generates an analogue output based on the amount of light reflected by the colour or pattern gradient 70. As the reader will now appreciate, this provides a progressive, stepped or sequential output. As shown in the figures, the optical sensor 38 is fixedly held adjacent the gradient reflector being the colour or pattern gradient 70. It will be understood that the receiving magnets 34 are attracted to, and moved by, the tank magnets 24, and may thus be considered to duplicate the movement of the tank magnets 24, so that the disk frame member 72 and colour or pattern gradient 70 also duplicate the movement of the tank magnets 24, and thus may be considered to duplicate the movement of the float sensor assembly or tank gauge 18 (or, more generally, the internal gauge). Of course, it is not necessary that the disk frame member 72 strictly duplicates the movement of the internal gauge - for example some gearing could be provided to increase or decrease sensitivity - provided that the colour or pattern gradient 70 indicates or replicates the movement of the internal gauge sufficiently that the movement of the colour or pattern gradient 70 provides an indication of the movement of the internal gauge which is sufficient to provide a desired level of accuracy.

The secondary chamber 66, illustrated in Figure 10, is configured to retain the indicator needle 36 and visual level labels or indicia display markings 60. In use, a user can view the visual indication of the tank level through the transparent lid 64, while the optical sensor provides a varying output relating to the liquefied gas level within the tank 14. This can be used to remotely monitor the fluid level and determine when the tank 14 needs to be refilled.

The reader should appreciate that the housing 40 may further contain an electronics chamber for retaining loT (Internet of Things) chips, circuit board (PCB), transmitter, communication means, or other electronic devices, for communication with a computing device configured to remotely monitor the fluid level within the tank 14.

As further illustrated in Figures 9 and 10, the disk frame member 72 and underside of the upper cover 44 include light shields 88, 90 to inhibit light entering the primary chamber 46 from between the edge of the central opening 84 and the protrusion 82, since excess light entering the primary chamber 46 may affect the operation of the optical sensor 38. The light shields 88, 90 are in the form of opaque axially short hollow cylindrical parts, arranged substantially coaxially with one light shield (in the illustrated embodiment the light shield 90 of the upper cover 44) extending into the other (in the illustrated embodiment the light shield 88 of the disk frame member 72) so that the overlap helps prevent ingress of light.

Figure 11 illustrates one embodiment of the colour or pattern gradient 70. In the present embodiment the gradient scale comprises eight segments, ranging from a plain white segment (which provides greatest reflectivity), through a series of progressively more concentrated markings, up to a segment having most concentrated markings (which provides least reflectivity). The skilled addressee should however appreciate that the gradient scale may be greyscale, coloured, patterned gradient, cross hatching gradient, gradient formed by dots, dashes or pixels.

Figure 12 illustrates the assembly of the gradient member 68 and positioning of the optical sensor 38, with the gradient pattern 70 removed. Figure 13, illustrates the position of the optical sensor 38 that is spaced apart from the gradient pattern 70 of the gradient member 68. The spacing may be between 0.01mm and 10mm and is one form may be 1mm. The spacing permits the reflection of the light off the gradient pattern 70, while ensuring that the optical sensor 38 does not come in contact with the gradient member 68 which could result in damage. Figure 13 also shows the central portion 74, which projects downwardly from the flange 86, and which includes the receiving passageways 80 for holding the cylindrical magnets 34 therein.

Figures 14 to 16 illustrate the gradient member 68 in three different positions as the float 30 moves within the tank 14, due to different fluid levels, resulting in three different amounts of light being received by the optical sensor 38. As illustrated, the optical sensor 38 remains in the same place during rotation of the disk frame member 72. In the present embodiment, the output voltage of the optical sensor 38, may be 3.4 volts when the disk frame member 72 is in the position illustrated in Figure 14 and no/minimal light is reflected by the part of the gradient member 68 being monitored by the optical sensor 38. As the disk frame member 72 rotates into the position illustrated in Figure 15, the optical sensor 38 receives more reflected light and the output voltage of the optical sensor 38, drops below 3.4 volts. As the gradient pattern continues to lighten, as illustrated in Figure 16, the output voltage of the optical sensor 38 continues to change, dependent on the amount of light received by the optical sensor 38.

The processor can then determine the level of fluid within the tank 14 by comparing the actual output voltage of the optical sensor 38 with a predetermined matrix or formula (or by other suitable means).

As the disk frame member 72 rotates the output voltage of the optical sensor 38 changes and the position of the needle 36 also changes relative to the display markings 60, as the needle 36 is coupled, via the protrusion 82, to the disk frame member 72.

Figure 17 corresponds to the position of the disk frame member 72 in Figure 14, wherein the needle 36 indicates that the tank 14 is generally full. Figure 18 corresponds to the position of the disk frame member 72 in Figure 15, wherein the needle 36 indicates that the tank is around 70% full. Figure 19 corresponds to the position of the disk frame member 72 in Figure 16, wherein the needle 36 indicates that the tank is less than 20% full. The needle 36 and display markings 60 thereby provide a visual indication means that is connected or in communication with the movable gradient member 68, to thereby provide a visual indication of the fluid level within the tank 14.

Figures 20 and 21 illustrate different configurations of the colour or pattern gradient 70 of the gradient member 68. In the embodiment of Figure 20 the gradient 70 comprises a plurality of segments, whereas in the embodiment of Figure 21 the gradient 70 provides a substantially continuous change in shade and/or colour. The reader should however appreciate that other pattern or colour configurations could be used without departing from the scope of the present disclosure. Figure 20 illustrates a configuration wherein the output signal rapidly drops as the tank 14 becomes empty.

Figures 22 to 30 illustrate an embodiment 2200 which is very similar to the embodiment of Figures 2 to 13 but is considered slightly more suitable for commercialisation. Because the embodiment 2200 of Figures 22 to 30 is very similar to the embodiment of Figures 2 to 13, it will not be described in detail, but rather the differences between the embodiment 2200 and the embodiment of Figures 2 to 13 will be described. In the following description parts of the embodiment 2200 which correspond to parts of the embodiment of Figures 2 to 13 are designated by corresponding reference numerals, but prefixed by the digits ‘22’. It should be appreciated that consideration of Figures 29 and 30 have substantial similarities to the cross sectional views of Figures 9 and 10 and, because they include cross hatching omitted from Figures 9 and 10 may assist in appreciation of the structure illustrated in the cross sectional views of Figures 9 and 10.

The embodiment 2200 provides a larger display dial 2259 than the embodiment of Figures 2 to 13, and consequently a larger set of display markings 2260 (compared to display markings 60) and a longer needle 2236 (compared to display markings 60) to provide a visual indication means that is easier to read. Figures 27 and 28 show exploded views, noting that Figure 28 shows the display markings 2260 on the display dial 2259, and also a gradient 2270 provided on gradient member 2268, which are omitted from Figure 27.

The embodiment 2200 also provides a larger diameter plug 2256 (compared to plug 56) for fitting optical sensor 2238 into aperture 2258 (corresponding broadly to optical sensor 38 and aperture 58 of the embodiment of Figures 2 to 13). The plug 2256, includes a groove 2257 for receiving a rim 2263 which defines the opening of the aperture 2258.

The embodiment 2200 also provides a retaining washer 2281 which in use is mounted about upwardly extending protrusion 2282 (corresponding broadly to upwardly extending protrusion 82 of the embodiment of Figures 2 to 13). The retaining washer 2281 helps retain receiving magnets 2234 in passageways 2280.

In a particular variant of the embodiment 2200, the diameter of the housing 2240 is 40 mm, and the distance between the centres of mounting holes 2252 is 47.5 mm. Of course, dimensions may be varied as desired and/or required for particular applications and according to the dimensions of a mount to which the apparatus is to be attached.

It will be appreciated that placement of the optical sensor relative to the gradient member 68, 2268 is important. In some cases attachment of the optical sensor to the wires of the optical sensor cable 54, 2254 and fitting of the plug 56, 2256 into aperture 58, 2258 has been found to be adequate. Flowever, if desired, the optical sensor may be attached to the wires and/or plug in a manner that more definitely fixes its location, for example by use of adhesive, by use of a physical aligner or sleeve into which the sensor fits in a predetermined alignment and position, by provision of a small circuit board or other mounting between the optical sensor and the wires, by a combination of these approaches, or by any other suitable means. Additionally, the sensor may be removable from the main part of the optical sensor cable to facilitate sensor replacement, if desired.

It will be appreciated that the housing should be made of a material that does not interfere with the magnetic coupling of the receiving magnets 34, 2234 to the tank magnets 24, for example a suitable plastic. It should also be appreciated that embodiments may utilise some commercially available parts. For example, in an embodiment the optical sensor 38, 2238, may be a model QRE113 optical sensor available from On Semiconductor (Semiconductor Components Industries,

LLC, Nasdaq: ON), the ball bearing 78, 2278 may be a commercially available 1.5mm stainless steel ball bearing (available for example, from Simply Bearings Ltd Simply Bearings Ltd of Leigh, Greater Manchester, UK), the receiving magnets 34, 2234 may be commercially available cylindrical Neodymium magnets of 4 mm diameter and 5 mm length (available for example, from AMF Magnetics of Rozelle, New South Wales), and the retaining washer 2281 may be a commercially available 4mm internal diameter shaft lock washer (available for example, as RS Stock No.: 172-335, from RS Components Pty Ltd of Smithfield. NSW). Of course, these examples should not be considered limiting.

The reader should appreciate that in the described embodiments the gradient reflector is movable and the optical sensor is fixed, however alternatively the optical sensor and/or display markings may be movable and the gradient reflector and/or needle may be fixed.

In other embodiments, the gradient member is elongate and slidable relative to the optical sensor. The elongate gradient member may have a gradient that changes from a first end to a second end. The optical sensor being positioned adjacent a surface of the elongate gradient member, wherein as it moves along the gradient member, it is able to measure the colour or pattern as it changes.

The skilled addressee will now appreciate advantages of the illustrated embodiments. Embodiments can be used in conjunction with conventional tank float gauges without requiring any modification, to provide both a visual display and an analogue output. The analogue output in one form, may be a variable output voltage, that can be used by a processor to determine a level of fluid within the tank, which may be converted into a digital signal and sent via a network to a remote monitoring computing device. Figure 31 illustrates schematically an arrangement including a fluid level gauge apparatus 3100 in accordance with the present disclosure attached to an enclosed container 3102, within which is provided a float gauge 3104. The fluid level gauge apparatus 3100 is provided with an external telemetry unit 3106 (connected by the optical sensor cable 3154) to the which contains loT chips, circuit boards (PCB), transmitters, communication means, or other electronic devices, for wirelessly transmitting fluid level measurement data to a monitoring station 3108. The fluid level measurement data may be transmitted direct to a local monitoring station 3108 (via, for example wi-fi) as indicated by arrow 3110 or via the Internet (illustrated schematically and designated by reference numeral 3112) or other communications network, as illustrated by arrows 3114. If desired the telemetry unit (and/or other electronics) could be accommodated in an electronics chamber provided within the housing 40, 2240. This can be achieved, for example, by enlarging the housing diameter (while still providing appropriate mounting holes 52, 2252 to allow mounting to a desired 20) and providing an annular electronics chamber, around the primary chamber 46.

Alternatively, the housing can be extended in the axial (vertical) direction, and an electronics chamber provided above the primary chamber 46 and below the secondary chamber 66, if the secondary chamber providing a visual indication of the tank level is desired).

If the visual display is not required for particular circumstances it may be omitted, providing a more economical apparatus than one which also provides a visual display dial, and a fluid level gauge apparatus which provides a useful electrical output providing information about fluid level.

The use of a low voltage system for monitoring the level in a tank has significate advantages for the longevity of the monitoring device and the simplicity of the design reduces the overall cost of the apparatus. Furthermore, in one embodiment where the disk frame member is configured to rotate through 360 degrees, accurate readings are obtained even when the fluid level gauge apparatus is coupled to a tank that is already filled.

Various features of the invention have been particularly shown and described in connection with the exemplified embodiments of the invention, however it must be understood that these particular arrangements merely illustrate the invention and it is not limited thereto.

Accordingly, the invention can include various modifications, which fall within the spirit and scope of the invention.