Tank refilling system

Abstract

A tank refilling system 110 and method, e.g. for retrofitting to a fuel tank of a combine harvester. The system comprises a controllable flow control valve 122 connected in a flow path between a liqui

Description

FIELD

[0001] This disclosure relates to the refilling of liquid tanks, for example refueling of a machine or vehicle. BACKGROUND

[0002] Refueling of utility and agricultural machines and vehicles presents difficulties. Refueling often takes place in environments where containments, such as, rain, dust or crop residue, are in the air and could enter a fuel tank opening when the filler cap is removed for refueling.

[0003] Often access to the fuel tank fill inlet is difficult. For example, it is common to have to refuel a combine harvester by climbing a ladder to stand on top of the vehicle, from where access to a refill opening is possible, while carrying a normal refueling gun. This is an inconvenient process for the user, as well as having associated risks.

[0004] These types of problem are not limited to refueling but can arise when filling or refilling tanks for other types of liquid, especially but not exclusively in an agricultural or other utility setting, such as on a construction site.

[0005] US 2008 / 0202600 discloses a fluid (e.g., fuel) level control system in which a hydraulically actuated shut-off valve is connected to a level sensor by hydraulic lines, so that refueling can be stopped by the shut-off valve when the desired level is sensed. This is however a complex configuration. BRIEF SUMMARY

[0006] The invention is defined by the claims. According to examples in accordance with a first aspect of the invention, there is provided a tank filling / refilling system comprising:

[0007] a liquid flow path having an inlet end for receiving liquid from a liquid supply and an outlet for delivering liquid into a liquid tank;

[0008] a controllable flow control valve located in the flow path proximal the inlet end for controlling the flow of liquid along the flow path;

[0009] a pressure sensor for sensing a pressure in the flow path upstream of the controllable flow control valve;

[0010] a controller for receiving pressure data from the pressure sensor and controlling the controllable flow control valve; and

[0011] a sensing valve inside the liquid tank, which sensing valve is driven towards a closed state to restrict the flow of liquid through the flow path when the liquid tank approaches a full state;

[0012] wherein the controller is configured to close the controllable flow control valve based on sensed pressure changes in the flow path induced by the closing of the sensing valve.

[0013] In the tank filling / refilling system, the inlet can be located at a position where it is conveniently connectable to a suitable liquid supply. This might be at a location which can be accessed from ground level on a combine harvester, for example. In this way, refilling can be easily carried out from ground level, enabling safer operation. Safety is also improved by the automatic stop system by which the controllable flow control valve is closed when refilling is complete. The flow path preferably connects to the liquid tank through a standard tank opening so that no modifications are needed to existing liquid tanks. In an embodiment, at least part of the flow path is permanently mounted to the fuel tank in a way that closes the filler opening so that contaminants in the air are not able to enter the tank during refilling. The flow path for example may extend through a cap which is fitted to a standard tank inlet opening (e.g., the filler neck).

[0014] The controllable flow control valve may be an on-off flow control valve and may be a solenoid valve which can thus be controlled electrically by the controller.

[0015] The sensing valve is for example a float valve. Thus, it may be a purely mechanical valve which is actuated by the liquid level. The float valve for example comprises a float which is coupled to a rotatable valve flap. The valve flap may be a circular flap that sits in a cylindrical opening in a pipe forming part of the flow path. The valve flap may rotate about an eccentric (non-central) axis of rotation axis. This gives a bistable behavior, in that a pressure on the inlet side of the valve flap produced by liquid flowing through the valve will generate a rotational torque to close the valve flap. Thus, as soon as the valve starts to close (under the action of the float) the prevailing pressure will tend to close the valve flap without needing any further rise in liquid level.

[0016] The float valve may be adapted to close when the tank has a predetermined liquid quantity. Thus, the tank can be considered to be "full" when the tank has this predetermined liquid quantity, which can be considered a default maximum quantity, even if there is additional volume in the tank which is not filled. The float valve may not fully close the flow path but may restrict liquid flow to the outlet.

[0017] The system may comprise a cap which connects a coupling pipe forming part of the flow path and the sensing valve, wherein the cap has a configurable size to enable connection to different designs of liquid tank. This enables the system to be a retrofittable system. The cap for example has a tiered structure, so that a tier size can be chosen that matches a liquid tank (such as a neck pipe of a liquid tank), and the cap can be cut to that size.

[0018] A breather line may be connected to the cap to allow air flow into and out of the tank as the liquid level in the tank changes. A rollover valve may also be provided in the breather line to prevent liquid escaping through the breather in the event that a vehicle or machine to which the system is mounted rolls-over.

[0019] The system thus connects to the tank via a cap, with no modification needed to the tank. Venting is preferably provided by a breather line and optionally a rollover valve. The cap is for example formed of a flexible material which can be cut to a suitable diameter. The risers of different tanks are different, both in height and diameter. The cap design for example enables connection to the riser of any diameter tank. The flow path may comprise a downpipe mountable to the cap to which the sensing valve is mounted. The length of the downpipe may be selected or adjusted to position the sensing valve at a desired instillation height in the tank. For example, the downpipe may be cut to length, or have its length extended depending on how high a filler neck of the tank is.

[0020] The controller is for example configured to obtain a reference pressure reading shortly (e.g., within 5 to 40 seconds, or 7 to 30 seconds, or 10 to 25 seconds) after opening the controllable flow control valve. This reference pressure is an indication of the pressure level which occurs at the beginning of refilling when the sensing valve will usually be fully open. It is used as a reference value, in that an increase in pressure relative to this reference pressure is indicative of a new flow restriction, in particular caused by closing of the sensing valve. Thus, relative pressures are used, so that the system can adapt to different supply lines and different machines or vehicles.

[0021] The controller is for example configured to close the controllable flow control valve (as a safety function) if the reference pressure exceeds a first threshold pressure and to generate a first error message.

[0022] This first threshold pressure is for example higher than is expected during normal refilling, and may for example indicate that the sensing valve is already closed even at the beginning of (attempted) refilling, either due to a fault or because the liquid tank is already full. The first threshold pressure is for example 1.5 bar (150kPa).

[0023] Closing the controllable flow control valve in this instance provides a safety function. The user is for example required to reset the system before it can be used further.

[0024] The controller is for example configured to close the controllable flow control valve when the sensed pressure rises to a first predetermined amount above the reference pressure.

[0025] This indicates that refilling is complete, because a pressure rise is seen when the sensing valve is closing or closed. The delivery of liquid is then halted by closing the controllable flow control valve. The first predetermined amount is for example 0.3 bar (30kPa) or 0.4bar (40kPa) or more generally in the range 0.2 bar (20kPa) to 0.5 bar (50kPa).

[0026] Once the controllable flow valve is closed at the end of refilling, the liquid supply is stopped. This may be carried out manually or the system may be configured to automatically stop the liquid supply, (e.g., by stopping a liquid supply pump). An output may for example be given to indicate when the pressure upstream of the controllable flow control valve has fallen and the refilling system can be disconnected from the supply line.

[0027] The controller is for example configured to obtain a maximum liquid supply pressure reading with the controllable flow control valve closed but with the liquid supply source operational (e.g., with a liquid supply pump running). This pressure reading is of use because it indicates the maximum pressure that will be present in the system, and hence it is not appropriate to set any threshold pressure values above this level.

[0028] For example, the controller is configured to close the controllable flow control valve if the reference pressure is within a second predetermined amount of the maximum liquid supply pressure, wherein the second predetermined amount is greater than the first predetermined amount.

[0029] If the first predetermined amount is 0.3bar (30kPa), the second predetermined amount is for example 0.5bar (50kPa). This ensures that the system can meet the required pressure to sense that refilling should be stopped. In other words, the first predetermined amount (e.g., 0.3 bar - 30kPa) above the reference pressure can be reached, without needing the pressure to exceed the maximum pressure that can be delivered by the system. In this example, the maximum pressure that can be delivered is at least 0.2 bar (20kPa) higher.

[0030] The controller is for example configured, when the controllable flow control valve is closed prior to refilling, to monitor the pressure of the flow path upstream of the controllable flow control valve and to open the controllable flow control valve for a predetermined period of time if a sensed pressure exceeds a maximum refilling system pressure.

[0031] This is used to protect the refilling system itself from a high pressure at the supply line. This may for example arise due to temperature variations. Opening the valve allows a release of pressure.

[0032] The controllable flow control valve is for example closed in the absence of power. This provides a safe system.

[0033] The refilling system may be used for filling any liquid tank and enables the user interface to be remote from the tank itself, so that for tanks which are in awkward locations, or tanks which have very high filling caps, the user when refilling the tank can be at a more convenient and safer location. The liquid tank may be a water supply or a supply of a waterbased chemical (such as fertilizer or pesticide) or indeed any liquid which is stored in tanks.

[0034] The inlet is for example for receiving a pumped liquid flow, and the controller is further configured to generate a pump control signal for controlling a pump which generates the pumped liquid flow. In this way, the system can also turn off the liquid supply pump which delivers the pumped flow to the refilling system when the tank is full. This avoids the user needing to manually turn off the main pump.

[0035] The tank filling / refilling system may comprise a flow control unit which includes at least the inlet, the controllable flow control valve, and the pressure sensor. The flow control unit may have a flow control unit outlet fluidly coupled with an outlet end of the controllable flow control valve.

[0036] The tank filling / refilling system may have a tank unit including at least a downpipe which defines part of the flow path and the sensing valve mounted to the downpipe, the tank unit having a tank unit inlet fluidly coupled with the downpipe.

[0037] The flow path may include a coupling pipe fluidly interconnecting the flow control unit outlet and the tank unit inlet. The tank unit may include a cap mountable about an inlet opening of the tank, the downpipe mounted to the cap for insertion into the tank through the inlet opening, and the cap defining a flow path between the downpipe and the tank unit inlet.

[0038] The flow control unit may comprise the controller.

[0039] The invention also provides a liquid supply system, comprising:

[0040] a liquid reservoir;

[0041] a pump having a pump inlet connected to the liquid reservoir and a pump outlet; and

[0042] a tank refilling system, comprising:

[0043] an inlet for connection to the pump outlet;

[0044] an outlet for delivering liquid to a liquid tank;

[0045] a controllable flow control valve between the inlet and the outlet;

[0046] a pressure sensor for sensing a pressure at the inlet; and

[0047] a controller for controlling the controllable valve,

[0048] wherein the controller is configured to close the controllable flow control valve based on sensed pressure changes, which pressure changes result when the liquid tank approaches a full state.

[0049] This liquid supply system combines a liquid reservoir and associated pump with the flow control section of the refilling system as defined above. The flow control section of the refilling system may be a standalone unit which is simply coupled to the pump outlet as an after-market add-on to the liquid supply system. However, it may instead be an integral part of the liquid supply system as originally manufactured. It is designed to interface with the sensing valve as discussed above. The liquid supply system may be a mobile reservoir (e.g., on the back of a truck or towed by a tractor) or it may be a static installation.

[0050] The controller of the liquid supply system may be configured to control the pump based on said sensed pressure changes. Thus, the controller controls the controllable flow control valve and the pump, to make the refilling operation as simple as possible for the user.

[0051] One particular example of the refilling system, and the liquid supply system, is for refueling a fuel tank.

[0052] The invention also provides an agricultural machine comprising:

[0053] a fue I ta n k; a n d

[0054] a refilling system as defined above, wherein the liquid tank is the fuel tank.

[0055] The agricultural machine is for example a combine harvester.

[0056] The invention also provides a method of controlling refilling of a liquid tank, wherein a controllable flow control valve and a sensing valve are connected in series between a liquid supply and the liquid tank, wherein the method comprises:

[0057] receiving a sensed pressure at the liquid supply;

[0058] determining from the sensed pressure that liquid is present at a predetermined level in the tank, based on the sensing valve being driven towards a closed state when the liquid tank approaches the predetermined level; and

[0059] controlling the controllable flow control valve to close by sensing pressure changes induced by the closing of the sensing valve.

[0060] The method may comprise:

[0061] obtaining a reference pressure reading shortly after opening the controllable valve;

[0062] closing the controllable flow control valve if the reference pressure exceeds a first threshold pressure and generating a first error message; and

[0063] closing the controllable flow control valve when the sensed pressure rises to a first predetermined amount above the reference pressure.

[0064] The method may comprise:

[0065] obtaining a maximum fuel supply pressure reading before the controllable flow control valve is opened to deliver liquid to the tank; and

[0066] closing the controllable flow control valve if the reference pressure is within a second predetermined amount of the maximum liquid supply pressure, wherein the second predetermined amount is greater than the first predetermined amount.

[0067] The controller is for example configured, when the valve is closed, to open the valve for a predetermined period of time if a sensed pressure exceeds a maximum refilling system pressure.

[0068] The invention also provides a computer program comprising code means which is adapted, when said program is run on a computer, to implement the method defined above. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] One or more embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0070] FIG. 1 shows a schematic diagram of a combine harvester;

[0071] FIG. 2 shows the combine harvester of FIG. 1 fitted with the refilling system of this disclosure;

[0072] FIG. 3 shows the components of one implementation of the refilling system;

[0073] FIG. 4 shows a method of operation of the system;

[0074] FIG. 5 shows the components of another implementation of the refilling system;

[0075] FIG. 6 shows the components of yet another implementation of the refilling system;

[0076] FIG. 7 shows a fuel cap suitable for fitting to a fuel neck of different sizes;

[0077] FIG. 8 show a cross sectional view through a molded cap portion of the fuel cap of FIG. 7 but with a modified design;

[0078] FIG. 9 shows an alternative embodiment of a fuel cap for fitting to a fuel tank filler neck of a specific size and threaded connection;

[0079] FIG. 10 shows the fuel cap of FIG. 9 in cross section;

[0080] FIG. 11 shows a float valve design; and

[0081] FIG. 12 shows a first example of a float valve in cross section in a closed state (left image) and an open state (right image); and

[0082] FlG. 13 shows a second example of a float valve in cross section in a closed state (left image) and an open state (right image). DETAILED DESCRIPTION

[0083] Embodiments of the disclosure will be described with reference to the Figures.

[0084] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. These and other features, aspects, and advantages of the apparatus, systems and methods of the present disclosure will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

[0085] The following description provides specific details of embodiments of the present disclosure in order to provide a thorough description thereof. However, a person of ordinary skill in the art will understand that the embodiments of the disclosure may be practiced without employing many such specific details. Indeed, the embodiments of the disclosure may be practiced in conjunction with conventional techniques employed in the industry. In addition, the description provided below does not include all elements to form a complete structure or assembly. Only those process acts and structures necessary to understand the embodiments of the disclosure are described in detail below. Additional conventional acts and structures may be used.

[0086] As used herein, the terms "comprising," "including," "containing," "characterized by," and grammatical equivalents thereof are inclusive or open-ended terms that do not exclude additional, unrecited elements or method steps, but also include the more restrictive terms "consisting of" and "consisting essentially of" and grammatical equivalents thereof.

[0087] As used herein, the term "may" with respect to a material, structure, feature, or method act indicates that such is contemplated for use in implementation of an embodiment of the disclosure, and such term is used in preference to the more restrictive term "is" so as to avoid any implication that other, compatible materials, structures, features, and methods usable in combination therewith should or must be excluded.

[0088] As used herein, the term "configured" refers to a size, shape, material composition, and arrangement of one or more of at least one structure and at least one apparatus facilitating operation of one or more of the structure and the apparatus in a predetermined way.

[0089] As used herein, the singular forms following "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0090] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0091] As used herein, spatially relative terms, such as "beneath," "below," "lower," "bottom," "above," "upper," "top," "front," "rear," "left," "right," and the like, may be used for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Unless otherwise specified, the spatially relative terms are intended to encompass different orientations of the materials in addition to the orientation depicted in the figures.

[0092] As used herein, the term "substantially" in reference to a given parameter, property, or condition means and includes to a degree that one of ordinary skill in the art would understand that the given parameter, property, or condition is met with a degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least 90.0% met, at least 95.0% met, at least 99.0% met, or even at least 99.9% met.

[0093] As used herein, the term "about" used in reference to a given parameter is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the given parameter).

[0094] This disclosure relates to a tank refilling system comprising a flow path along which liquid flows from an inlet end to the interior of the tank. The inlet end receives liquid from a liquid supply. A controllable flow control valve is located proximal the inlet end. A sensing valve is provided in the tank. The sensing valve closes to restrict flow along the flow path when liquid tank is full. The controllable flow control valve is closed when the sensing valve closes, by sensing an increase in pressure in the flow path. This system enables refilling of a tank from a remote location to the filling opening of the tank, for example from ground level for a liquid tank which is raised above ground level, and it implements an automatic shut off function.

[0095] This disclosure relates generally to a tank refilling system. It may be used for controlling the flow of any liquid to a tank for storing the liquid. Typically, it relates to large volume liquid storage. It will be understood that whilst the system is referred to as a refilling system, it can also be used for first filling of a tank.

[0096] The disclosure in one particular implementation relates to refilling a fuel tank. This implementation is of interest for any vehicle or other machine which needs refueling from a fuel supply line and has a fuel tank which is difficult to access. For example, the fuel tank may be raised a significant height above the ground so that a user cannot access the fuel tank opening from ground level. An example is large agricultural machinery, such as combine harvesters.

[0097] The disclosure may also be of interest for refueling vehicles and machines in environments where contaminates are in the air as it enables refilling the fuel tank without the need to remove a conventional filler cap. This reduces the risk of fuel in the tank being contaminated and is of interest even for vehicles and machines where the fuel tank filler opening is easily accessible. Contaminates could included dust, crop residues and / or rain, for example.

[0098] The invention will be described with reference to one implementation example, for refueling a combine harvester. The combine harvester has a fuel tank. A fuel supply includes a fuel pump, and a fuel supply line used to refuel the combine harvester. These are discussed below. However, it should be understood that more generally the invention applies to a liquid tank, liquid pump, and liquid couplings and supply lines.

[0099] A combine harvester typically includes a threshing system for detaching grains of cereal from material other than grain, such as cobs, stems and seed pods, a separating apparatus downstream of the threshing system, and a grain cleaning apparatus (known as the cleaning shoe) for receiving grain from the separating apparatus. A stratification pan aims to stratify the material into a layered structure of grain at the bottom and light chaff and other material other than grain (MOG) at the top. The grain is collected in a grain bin, and from the grain bin the grain can be unloaded, for example to a trailer pulled by a tractor which runs alongside the combine harvester.

[0100] FIG. 1 shows a schematic diagram of a combine harvester.

[0101] The combine harvester 10 includes the threshing system 20 for detaching grains of cereal from the ears of cereal, and the separating apparatus 30 which is connected downstream of the threshing system 20. The threshing system comprises one or more threshing units, in particular rotors, and associated concaves. The separating apparatus 30 for example includes a plurality of parallel, longitudinally-aligned, straw walkers for the case of a so-called straw-walker combine. The grains after separation by the separating device 30 pass to a grain cleaning apparatus 40.

[0102] The grain cleaned by the grain cleaning apparatus is delivered to a grain bin 50 by a filling auger. Grain from the grain bin is removed from the combine harvester by an unloading tube 60.

[0103] The combine harvester has a front elevator housing 12 at the front of the machine for attachment of a crop cutting head (known as the header, not shown). The header, when attached, serves to cut and collect the crop material as it progresses across the field, the collected crop stream being conveyed up through the elevator housing 12 into the threshing system 20.

[0104] The threshing system 20 is for example a tangential-flow 'conventional' threshing system, i.e., formed by rotating elements with an axis of rotation in the side-to-side direction of the combine harvester and for generating a tangential flow. There are also axial threshing systems, i.e., formed by rotating elements with an axis of rotation in the longitudinal direction (direction of travel). For example, the threshing section may have axially-aligned rasp bars spaced around the front section whilst the separating section has separating elements or fingers arranged in a pattern, e.g., a spiral pattern, extending from the rasp bars to the rear of the rotor.

[0105] The size of a combine harvester is such that the fuel tank 70 is raised high above the ground. To provide access to the filling neck 72 of the fuel tank 70 (and for other inspection / maintenance purposes) a ladder 74 is provided, leading to a platform area with a safety rail 76. Thus, the user has to climb the ladder to fill the fuel tank. This is achieved with a standard refueling nozzle, which uses a venturi pipe to sense pressure change caused by the presence of fuel in order to implement a cut off when the fuel tank is full.

[0106] The above description of a typical combine harvester is provided by way of background and it should be appreciated that the system and methods for filling a tank as described herein are not limited to use with a combine harvester having all the features as described but can be adopted for refueling any combine harvester or indeed to any other vehicle or machine, or for filling any suitable liquid tank.

[0107] This disclosure provides a system for refilling a liquid tank, and in this example for refueling. The system connects to a fuel supply line and implements its a semi or fully automatic shut off when the fuel tank is full.

[0108] The system of the invention comprises a first, flow control section at the liquid supply side which has a valve to implement an automatic shut off when the liquid tank is full, and a tank unit mounted to the tank to be filled and which performs sensing of when the liquid tank is full. There are different possible implementations.

[0109] FIG. 2 shows the combine harvester of FIG. 1 fitted with a first implementation of the tank refilling system 100 of this disclosure used for refueling the combine harvester. Thus, the tank refilling system will be described below as a refueling system.

[0110] In this first implementation, the whole refueling system is attached to, and thus forms part of, the combine harvester. In a second implementation described below, only the tank unit is associated with the specific combine harvester, and a flow control section with a controllable flow control valve unit may be used with multiple tank units. In that case, the flow control section may form a modification to a liquid reservoir system (i.e., liquid reservoir and associated pump). The flow control section may then be a standalone unit (e.g., a main unit) which is provided as an after-market modification to a liquid reservoir system, or it may be an integral part of the originally manufactured liquid reservoir system.

[0111] The refueling system 100 of the first implementation shown in FIG. 2 comprises the flow control section 110 which is positioned at a location convenient for a user who wishes to refuel the combine harvester, and a tank unit 111 mounted to an inlet opening (e.g., a filler neck) of the fuel tank 70, the flow control section 110 and the tank unit being fluidly connected by a coupling pipe 150. The fuel coupling pipe 150 for example is a riser pipe with the tank unit higher than the flow control section. The flow control section 110 may thus be considered to be, or to be part of, a ground level unit, mounted to the vehicle somewhere accessible from the ground. The flow control section 110 can be connected to any suitable electrical power source on the vehicle. The fuel coupling pipe is for example a flexible hose which can be cut to length.

[0112] Refueling can be easily done from ground level, enabling safer operation. Safety is also improved by an automatic stop system when refueling is complete.

[0113] FIG. 3 shows the components of the refueling system 100.

[0114] A fuel supply hose 114 is connected to a fuel inlet of the system 100 by means of an inlet connector 112 provided in the flow control section 110. The fuel supply hose 114 terminates with a corresponding connector 116 (rather than a pistol type nozzle trigger), so that the refueling system is coupled to the fuel supply hose 114 in a rigid leak-proof manner. The connectors 112,116 may form a flat face quick coupling, which prevents leakage when the coupling is detached.

[0115] There is a fluid path between the inlet, i.e., the inlet connector 112, and an outlet 120 of the flow control section 110. The outlet 120 may be an outlet connector 120. A controllable flow control valve 122 is provided in series along this fluid path, i.e., between the inlet 112 and the outlet 120 of the flow control section.

[0116] The flow control valve 122 is an on / off valve which permits liquid to flow from the inlet 112 to the outlet 120 of the flow control section when open and prevents liquid flow when closed. Any suitable controllable on / off valve may be used. Typically, the controllable flow control valve is a solenoid valve. In an embodiment, the controllable flow control valve 122 has a control shaft 124 for setting the valve position. The shaft is rotated by an actuator 126 in the form of a solenoid actuator carried by a printed circuit board 128.

[0117] A pressure sensor 130 is provided for sensing a pressure in the flow path upstream of the controllable flow control valve 122, hence at the fuel supply inlet 112. A controller 132 is provided for controlling the controllable flow control valve 122.

[0118] The flow control section 110 basically allows a flow from the fuel supply line to the outlet connector 120 or else blocks that flow, based on whether refueling is in progress or is complete, or indeed based on detection of any alarm issues, as explained below.

[0119] The tank unit 111 includes a downpipe 171 which extends inside the tank and has a system outlet 162 towards its lower end through which fuel is dispensed into the tank. The fuel coupling pipe 150 leads to an inlet 164 of the tank unit 111 which is fluidly coupled to the downpipe 171. A fuel level sensing valve 160 (and more generally a liquid level sensing valve for the more general implementation) is mounted to the lower end of the downpipe 171 inside the fuel tank. The fuel sensing valve 160 closes when the fuel tank is full to restrict the flow of liquid to the outlet 162. As explained in more detail below, the fuel sensing valve 160 for example comprises a float valve which closes when the fuel level in the tank reaches a predetermined level. The use of a float valve means that no electronics are required to be mounted in the fuel tank. Thus, the sensing valve is purely mechanical.

[0120] The controller 132 of the flow control section 110 closes the controllable flow control valve 122 when the fuel sensing valve 160 closes. Closing of the fuel sensing valve is sensed by a pressure increase caused by the additional flow restriction presented by the closed or closing fuel sensing valve. The controller 132 in this embodiment is a separate, dedicated controller for the refilling system but in alternative embodiments, at least part of the controller logic can be provided by a control system of the vehicle or other machine on which the system is provided.

[0121] The tank unit 111 may include a fuel cap 170 which mounts to a filler neck or other inlet opening of the fuel tank. The fuel cap 170 is designed (or adapted) to the particular fuel tank, so that the fuel tank does not need any modification. The downpipe 171 and the fuel sensing valve 160 extend below the fuel cap 170 by an amount which depends on the design of the fuel tank.

[0122] The system may for example be adaptable to different fuel tanks by selecting a downpipe 171 of appropriate length to set the depth of the fuel sensing valve. The downpipe may be removably mounted to the fuel cap so that a downpipe of appropriate length can be selected. In an embodiment, the downpipe can be cut to length and / or several downpipe sections connected to form the downpipe.

[0123] FIG. 3 also shows a breather line 172 connected to the fuel cap and a rollover valve 174 in the breather line. The rollover valve shuts off in the event that the combine harvester has overturned to prevent fuel spillage in a known manner. The breather line may lead to an air filter 176.

[0124] The breather connection allows air to leave and enter the tank as the fuel level changes.

[0125] Finally, FIG. 3 shows a start switch 180 and a reset switch 182, as well as an output indicator 184 such as an LED or array of LEDs, and their operation is explained below.

[0126] The basic function of the control system is to shut off delivery of fuel when an increase in pressure is detected, caused by the closing of the fuel sensing valve 160. However, various other pressure levels are sensed to ensure correct operation of the system.

[0127] In one embodiment, the controller 132 is a processor-based device, such as one or more computers and may comprise one or more processors, input / output (I / O) interface(s), and memory. Thus, in embodiments, the controller 132 may include one or more processor(s) and associated memory device(s) configured to perform a variety of computer-implemented functions. As used herein, the term "processor" refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits. The memory may include any one or a combination of volatile memory elements (e.g., random-access memory RAM, such as DRAM, and SRAM, etc.) and non-volatile memory elements (e.g., ROM, hard drive, tape, CDROM, etc.). The memory may generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s), configure the controller 132 to perform various computer-implemented functions, such as one or more aspects of the control algorithm for controlling operation of the refilling system as described herein. The controller 132 receives pressure data from the pressure sensor 132 as well as inputs from the user interface buttons 180,182 and is operative to generate control signals for controlling operation of the controllable flow control valve 122 based on the pressure data according to one or more algorithms.

[0128] FIG. 4 shows the method of operation of the system and explains the various pressures that are sensed.

[0129] The system has an idle state 200. In this state, the controllable flow control valve 212 is closed, so that no fuel flow is permitted through the flow control section 110. An indicator (of the output indicator 184) for example is used to indicate when a flow is taking place (e.g., a green light is output) and when no flow is taking place (e.g., the green light is out). Even in this idle state, the pressure may be periodically measured in step 202 until a start command is received in step 210 resulting from operation of the start switch 180.

[0130] If the measured pressure is above a maximum system pressure (e.g., in the range 4 bar = 400kPa to 10 bar = IMpa, such as 4.5 bar = 450kPa) as tested by the pressure sensor in step 204, the controllable flow control valve is opened in step 206 for a short duration such as 2 seconds. This releases the pressure. The pressure is released into the fuel coupling pipe. This only requires a very small flow of fuel from the fuel supply to accompany the release of pressure. The purpose is to protect the flow control section part from pressures above the intended design pressure, for example to ensure couplings are not exposed to pressures above their design limits. For example, in circumstances where the vehicle is exposed to hot sunshine, fuel retained in the system between the inlet coupling 112 and the controllable flow control valve 122 may become heated and its pressure rise. This step is taken to monitor the pressure of this retained fuel and to release the pressure if it becomes too high and may be carried out even without a fuel supply 114 connected to the refilling system.

[0131] Once a start signal has been received, the green light is turned on in step 212. A maximum pressure is then measured with the fuel supply pump running but before opening the controllable valve, in step 214. The use of this measured maximum pressure is explained below.

[0132] The controllable flow control valve is then opened in step 216 to begin refueling.

[0133] In step 218 a pressure measurement is made after opening the valve 122 to determine a reference pressure. The reference pressure may be determined shortly after opening the controllable valve 122 has opened but at a time when the system has settled to a steady state. In embodiments, reference pressure is determined within a period of around 5 to 40 seconds, or 7 to 30 seconds, or 10 to 25 seconds, or around 22 seconds after the controllable flow control valve 122 is opened for refueling. During this initial period after the solenoid valve 122 is opened, the system may monitor the pressure and record the lowest value as the reference pressure to allow the system to settle.

[0134] This reference pressure is an indication of the pressure level which occurs at the beginning of refueling when the fuel level sensing valve 160 is usually fully open. It is used as a reference value, in that an increase in pressure relative to this reference pressure is used to detect a flow restriction, in particular caused by closing (partial or complete) of the fuel sensing valve 160.

[0135] The reference pressure is compared with two thresholds. A first threshold Thl is applied in step 220, and is for example 1.5 bar (150kPa). If the reference pressure exceeds this threshold (but does not reach the second threshold which is explained below) a first error message is output in step 222.

[0136] This first error message indicates that the sensed reference pressure is higher than is expected during normal refueling, and may for example indicate that the fuel sensing valve 160 is already closed even at the beginning of (attempted) refueling, either due to a fault or because the fuel tank is already full. The first threshold pressure is for example 1.5 bar (150kPa). The output indicator for example provides the first fault indication as a fast flashing LED signal. The controllable flow control valve is then turned off.

[0137] To get out of this shut down state, the reset button 182 needs to be pressed (not illustrated in FIG. 4).

[0138] A second threshold Th2 is applied in step 224. Here, it is determined if the sensed reference pressure is only just below the maximum fuel supply pressure, in particular within a predetermined amount from the maximum fuel supply pressure. If the reference pressure is too close to the maximum fuel supply pressure, it means a desired margin cannot be added for sensing the closure of the fuel sensing valve. If this is the case, a second fault indication is provided in step 226. The controllable flow control valve 122 is turned off (closed) and to get out of this shut down state, the reset button 182 again needs to be pressed (not illustrated in FIG. 4).

[0139] The second fault indication is also for example provided as a fast flashing LED signal. It may be the same generic fault indication, or the two faults may be differently identified.

[0140] If there are no such faults, the pressure is continuously monitored in step 230 while refueling. It is tested if the pressure exceeds the reference pressure by a first predetermined amount PAI (0.3bar =30kPa in this example). The predetermined amount shown in step 224 is a second predetermined about (0.5bar = 50kPa in this example). The second predetermined amount is greater than the first predetermined amount, and this means the system can meet the required pressure to sense that refueling should be stopped.

[0141] The controllable flow control valve 122 is closed when the sensed pressure in step 230 rises to the first predetermined amount above the reference pressure, as tested in step 232. Once this pressure is reached, filling is complete as shown in step 240.

[0142] After refueling, the controllable flow control valve 122 is closed, the fuel supply pump is stopped, and the system returns to its idle state. With the fuel supply pump stopped, the pressure upstream of the controllable flow 122 valve will fall. The liquid pressure may be monitored using the pressure sensor 130, and a signal provided to a user to indicate when it is safe to disconnect the inlet fuel hose 114 from the system. For example, a slow flashing signal may be provided when the pressure has fallen to a level that is safe to disconnect the fuel hose 114.

[0143] To provide a failsafe function, the controllable flow control valve 122 may be biased to a closed position in the absence of power. This provides a safe system. Also, if at any point the connection to the pressure sensor breaks (e.g., in the absence of a meaningful pressure signal at the controller) or the fluid coupling 112,116 to the fuel supply breaks or is disconnected, the system is configured to close the controllable flow control valve 122 and a fault message is generated.

[0144] The reset button may be used to turn off and on the overall system, by removing and restoring power to the system. After a voltage has been restored, the system returns to the initial idle state 200.

[0145] In this first implementation, once fitted, the entire refueling system remains mounted on the vehicle and the flow control section 110 is permanently coupled to the tank unit 111. The connection made by the user is the connector 112,116 to the external fuel supply. The system may be provided as an after-market add-on, but it could equally be designed to be built-in during manufacture or as a dealer-fitted accessory.

[0146] FIG. 5 shows a second implementation in which the flow control section 110 and the tank unit 111 are releasably connectable so that the flow control section 110 can be mounted separately from the vehicle or other machine. The outlet from the flow control section 110 is now another quick release coupling (flat face quick coupling) comprising male and female parts 120a, 120b. The tank unit 111 is fitted to the combine harvester, or other vehicle or machine, and a fuel coupling pipe 150 from the tank unit 111 terminates at a connector part 120a. A hose 260 with suitable end connectors may be connected between the coupling parts 120a, 120b (as shown in FIG. 6). The flow control section 110 in this embodiment may be coupled to the fuel supply which is used to refuel the tank. The fuel supply may be a fixed fuel supply reservoir or it may be a movable reservoir, for example mounted at the back of a truck. In this example, there may be a single flow control section 110 associated with a fuel reservoir, and a number of tank units 111, each fitted to a respective vehicle or other type of machinery. Thus, an overall system can comprise a master unit (i.e., the flow control section 110) and a set of multiple tank units 111. In this case, the connection made by the user is the connection between the flow control section 110 and the tank unit 111, namely connection 120a, 120b. Though in some embodiments a user may also make a connection between the flow control section 110 and the liquid supply.

[0147] In the two implementations described above, the flow control section 110 connects to an external fuel supply or fuel reservoir. That external supply or reservoir comprises a pump. Typically, a user turns on the pump, performs refilling, then turns off the pump. When the valve 122 has shut off because the tank is full, the pump is driving against a high resistance, and this will cause damage if the pump is left on for a prolonged period. Thus, the user needs to turn off the pump without undue delay.

[0148] FIG. 6 shows a third implementation, which is suitable when the flow control section 110 is associated with a fuel reservoir which can be stationary or mobile, as in the example of FIG. 5. It also shows a set of tank units 111 which are associated with the single flow control section 110.

[0149] The fuel reservoir 250 has an associated pump 252, and the flow control section 110 is integrated with the fuel supply system. The flow control section 110 in the embodiment automatically controls the pump 252. In particular, when the liquid tank is full, in addition to switching off the controllable flow control valve 122, the main fuel pump 252 can be turned off. The controller 132 may also be configured to start the pump 252 to commence refueling prior to opening the controllable flow control valve 122, say in response to a user input.

[0150] The main fuel pump 252 may be a 12V to 48 V DC pump for a mobile fuel reservoir, or it may be a 240V or 110V AC pump for a static installation. The flow control section 110 may thus be compatible with all electrical supply types so that it can be wired to a static or mobile fuel reservoir system and then control the fuel pump.

[0151] Returning to FIG. 5, an adaptation is shown to allow the flow control section 110 to control the pump. The pump power supply is delivered via a wired interrupt connector 190 at the flow control section 110 so that the pump can be switched on and off using a relay 192. This process is controlled by the controller 132. The power supply for controlling the controllable flow control valve 122 of the flow control section 110 may for example be a 12 V or 24 V supply, but this may be generated from an external 110V or 240V supply if that is what is available at the fuel reservoir system.

[0152] In this example, the user simply connects a hose 260 between the flow control section 110 and the tank unit 111, or to a fluid conduit leading to the tank unit 111, using quick connectors at each end. The flow control section 110 is located at a convenient location on the fuel reservoir system, and the connection to the tank unit 111 is also at a convenient location so that the hose 260 can easily be connected. The hose 260 is for example part of the fuel reservoir system so that the connection to the flow control section 110 remains made and only a connection between the remote end of the hose 260 and the tank unit 111 needs to be completed by the user.

[0153] As mentioned above, the system may be designed to be retrofittable to a range of different machines and to different external fuel supplies or fuel reservoirs. In particular, the only connections needed are an electrical power supply and a connection to the fuel tank, so that the fuel sensing valve can be inserted.

[0154] FIG. 7 shows a fuel cap suitable for fitting to a fuel neck of different sizes. It comprises a flexible a tiered grommet 300 and a molded cap portion 301. The cap portion has a first connection 302 for coupling to the fuel coupling pipe 150 and a second connection 304 for a breather pipe. The downpipe 171 to the fuel sensing valve extends down from the fuel cap portion. There is also a third connection 306 which is a cross sectional view through part of the fuel cap. This is dimensioned to receive a standard pistol type fuel filler nozzle to allow for refueling in a conventional manner, if the refueling system fails. The additional connection would usually be closed by a screw cap or plug. FIG.8 shows a modified version of the cap portion 301 but without the third connection 306, which could be omitted. FIG. 8 also illustrates a threaded connection 305 for mounting the downpipe 171 to the cap portion 301. A similar arrangement may be provided in the fuel cap of FIG. 7

[0155] The tiered grommet may be made of an elastomeric or other flexible material and has sections of different diameter. The grommet is cut so that the desired size section is at the bottom. This bottom section fits over (and around the outside of) the fuel riser pipe / filler neck. It is then held in place using a pipe clamp. Thus, it is sealingly attached to the fuel riser pipe and remains in place. The grommet may also be clamped to a periphery of the molded cap portion 301.

[0156] By way of example, the different tiers may have outer diameters of 60mm, 85mm, 100mm, 115mm, 130mm, 145mm and 158mm.

[0157] FIG. 9 shows an alternative fuel cap design. The full cap has a screw connection 400 for fitting over a standard projecting threaded filler neck. There is again a first connection 402 for coupling to the fuel coupling pipe, a second connection 404 for a breather pipe, and a third connection 406 for standard refueling. The breather line can also include a roll over valve as mentioned above, but it is not shown in FIG. 8.

[0158] FIG. 10 shows the design of FIG. 9 in cross section. It shows that the connections 402, 406 connect to the same volume which leads to the downpipe (not shown), whereas the connection 404 for venting connects to the space around the downpipe, hence it connects to the air space above the fuel level.

[0159] Instead of the rubber grommet or screw fitting designs, any other suitable interface to a fuel riser pipe, or indeed to a fuel cap opening, may be used.

[0160] As explained above, the sensing that the fuel tank is full is based on sensing a pressure in the flow control section 110, which results from the closing of a liquid level sensing valve in the tank. The preferred implementation of the fuel sensing valve is a float valve as shown in more detail in FIG. 11.

[0161] As explained above, the float valve 160 is at the end of a downpipe and has a connector 500 for connecting to the downpipe. The float valve 160 can be considered an extension of the downpipe and it has a housing defining the screw connector 500 and an internal liquid passage which is an extension of the internal liquid passage through the downpipe and leads to an outlet 162 through which fuel enters the fuel tank. A float 502 floats on the fuel surface (once the fuel level is high enough), and it is coupled to a valve actuator 504 by a link 506. Thus, the rising and falling of the float rotates the valve actuator 504 about a pivot axis 508. The pivot axis rotates an internal valve member in the form of a valve flap in the fluid path upstream of the outlet 162. The float is aligned axially to the axis of the downpipe and is constrained to move along this axis when it floats. This enables the float valve to be used where there is limited space in the fuel tank.

[0162] FIG. 12 shows a first implementation of the float valve in cross section in a closed state (left image) and in an open state (right image). The valve member 510 (valve flap) is in series along the internal passageway through the float valve and its rotational position determines if the passageway is open or closed.

[0163] FIG. 13 shows a second implementation of the float valve in cross section again in a closed state (left image) and in an open state (right image). The valve member 510 (valve flap) is again in series along the internal passageway through the float valve and its rotational position determines if the passageway is open or closed.

[0164] There is a lower rim 511 around part of the valve member 510 and an upper rim 512 around another part. When the valve member is closed (left image), further rotation of the valve member is limited by the rims 511, 512 and they absorb some of the forces on the unit so that reduced forces are experienced by the float 502. In this example, the valve flap is eccentrically mounted on the pivot axis 508. Thus, a first valve flap area 510a is to one side of the pivot axis and a second valve flap area 510b is to the opposite side of the pivot axis. In the closed state, the larger force present at the larger side (the first valve flap area 510a) compared to the smaller side (the second valve flap area 510b) provides a torque which tends to close the valve flap.

[0165] The valve is driven towards its closed state when the fuel tank approaches a full state. During this process, the flow resistance presented by the valve increases, even before the valve is fully closed. Thus, pressure changes in the flow path are induced by the closing of the valve, even before it reaches a fully closed state.

[0166] When the float is in its lowest position (which applies for any fuel level below the bottom of the float valve), the valve flap 510 is in an open position. As the float lifts, it starts to close the valve flap. Due to the eccentric mounting of the valve flap explained above, once the valve begins to close, the fuel flowing through the internal passageway (and hence the pressure) will result in a greater force on the larger side of the valve flap tending to move the valve flap to a closed position lifting the float relative to the level of the liquid in the tank. This is represented by the flow arrows in the left image of Figure 13. Thus, as soon as the valve flap starts to rotate, e.g., to around 5 to 15 degrees, it has a bistable behavior and is driven fully closed. Thus, the forces that are present lift the float, even above the fuel level. This provides a rapid and reliable shut-off of the solenoid valve. The weight of the float 502 is sufficient to hold the valve flap 510 open against the force applied by liquid flowing through the valve until the float has been lifted by the level of the fuel in the tank by a predetermined amount (e.g., to move the valve flap by around 5 to 15 degrees).

[0167] In the closed position, the liquid flow path may not be fully closed but is significantly restricted sufficient to result in an increase in pressure that can be detected at the inlet end by the pressure sensor 130.

[0168] When the controllable flow control valve 122 has been closed and the flow of fuel through the valve stops, the float may drop slightly (since it was previously pulled up by the pressure acting on the valve flap). This will move the valve flap towards the open position. In the event someone attempts to refuel when the tank is full, the solenoid valve will open but the flow of fuel will quickly close the float valve and the solenoid valve will be closed after only a small amount of fuel has been introduced. The system is calibrated so that the tank will not be easily over filled. The control system could be modified to limit the number of times refueling can be started within a given time limit after it has been detected that the tank is full.

[0169] The system does not require the fuel tank to be opened to perform refilling. Instead, one or more connector couplings are made. By having a closed system, no debris (or rain or snow) can enter the fuel tank. By providing a retrofit product, existing refueling machines do not need to be changed in any way, in which case, for example, the machine's warranties remain.

[0170] To enable retrofitting to multiple machines or vehicles, the system is for example designed to operate with any expected external fuel supply delivery parameters, such as supply pressure in the range 0 to 6 bar (600kPa) and 0 to 200 liters / minute flow rate.

[0171] The invention has been described with reference to a combine harvester, in which the fuel tank is usually high up at the rear and difficult to get to. However, the system could potentially be used anywhere there is a need to fill a liquid tank, and especially where the tank is difficult to access.

[0172] It will be appreciated the various pressures, thresholds, limits and flow rates mentioned above in relation to the embodiments described are exemplary only that that the actual pressures, thresholds, limits and flow rates for any given system according to the disclosure can be adapted to meet the requirements of different tanks and liquid supplies.

[0173] As will be clear from the description above, the embodiments of the present disclosure can be made into a comprehensive refilling system for several different machines of different kinds. The liquid tank of the target to be refilled can be located higher than the ground level, in which case safety is achieved with the help of the system, because climbing can be reduced. By installing the system on any vehicle or machine having a tank to be refilled, a clean refilling (e.g. refueling) process can be achieved because the system is closed. This means that when refueling with the system, debris from the outside, which is often on the surfaces of the machines, which the wind can throw into the tank, or for example rainwater, does not get into the fuel tank.

[0174] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

[0175] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0176] If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be equivalent to the term "configured to".

[0177] Any reference signs in the claims should not be construed as limiting the scope.

[0178] All references cited herein are incorporated herein in their entireties. If there is a conflict between definitions herein and in an incorporated reference, the definition herein shall control.

Claims

What is claimed is:

1. A tank refilling system (100) comprising:a liquid flow path having an inlet (112) for receiving liquid from a liquid supply (114) and an outlet (162) for delivering liquid into a liquid tank (70);a controllable flow control valve (122) located proximal an inlet end of the flow path for controlling the flow of liquid along the flow path;a pressure sensor (130) for sensing a pressure in the flow path upstream of the controllable flow control valve (122);a controller (132) for receiving pressure data from the pressure sensor and controlling the controllable flow control valve (122);anda sensing valve (160) for mounting inside the liquid tank, which sensing valve (160) is driven towards a closed state to restrict the flow of liquid through the flow path when the liquid tank approaches a full state;wherein the controller (132) is configured to close the controllable flow control valve (122) based on sensed pressure changes in the flow path induced by the closing of the sensing valve.

2. The system of claim 1, wherein the sensing valve (160) is a float valve and / or thecontrollable flow control valve (122) is a solenoid valve.

3. The system of claim 2, wherein the sensing valve comprises a float valve having a valveflap with a non-central axis of rotation.

4. The system of any one of claims 1 to 3, comprising a cap (170) which connects a coupling pipe (150) forming part of the flow path and the sensing valve (160), wherein the cap has a configurable size to enable connection to different designs of liquid tank.

5. The system of any one of claims 1 to 4, wherein the controller (132) is configured to obtain a reference pressure reading after opening the controllable flow control valve (122) to deliver liquid to the tank, wherein the controller (132) is configured to close the controllable flow control valve when the sensed pressure subsequently rises to a first predetermined (PAI) amount above the reference pressure.

6. The system of claim 5, wherein the controller (132) is configured to close the controllable flow control valve (122) if the reference pressure exceeds a first threshold pressure (Thl) and to generate a first error message.

7. The system of claim 5 or 6, wherein the controller (132) is configured to:obtain a maximum liquid supply pressure reading (Pmax) with the controllable flow control valve (122) closed; andclose the controllable flow control valve if the reference pressure is within a second predetermined amount (PA2) of the maximum liquid supply pressure (Pmax), wherein the second predetermined amount is greater than the first predetermined amount8. The system of any one of claims 1 to 7, wherein the controller (132) is configured, when the controllable flow control valve (122) is closed, to monitor the pressure in the flow path upstream of the controllable flow control valve (122) and to open the controllable flow control valve (122) for a predetermined period of time if a sensed pressure exceeds a maximum refilling system pressure.

9. The system of any one of claims 1 to 8, wherein the inlet is for receiving a pumped liquid flow, and wherein the controller is further configured to generate a pump control signal for controlling a pump which generates the pumped liquid flow.

10. A liquid supply system, comprising:a liquid reservoir (250);a pump (252) having a pump inlet connected to the liquid reservoir and a pump outlet; anda tank refilling system, comprisingan inlet (112) for connection to the pump outlet;an outlet (120) for delivering liquid to a liquid tank;a controllable flow control valve (122) between the inlet (112) and the outlet (120);a pressure sensor (130) for sensing a pressure at the inlet (112); anda controller (132) for controlling the controllable valve, wherein the controller (132) is configured to close the controllable flow control valve (122) based on sensed pressure changes, which pressure changes result when the liquid tank approaches a full state.

11. The liquid supply system of claim 10, wherein the controller is further configured tocontrol the pump based on said sensed pressure changes.

12. An agricultural machine comprising:a fuel tank; anda refilling system as claimed in any one of claims 1 to 9, wherein the liquid tank is the fuel tank.

13. A method of controlling refilling of a liquid tank, wherein a controllable flow control valve (122) and a sensing valve (160) connected in series between a liquid supply and the interior of the liquid tank, wherein the method comprises:receiving a sensed pressure at the liquid supply;determining from the sensed pressure that liquid is present at a predetermined level in the tank, based on the sensing valve being driven towards a closed state when the liquid tank approaches the predetermined level; andcontrolling the controllable flow control valve (122) to close by sensing pressure changes induced by the closing of the sensing valve.

14. The method of claim 13, comprising:obtaining a reference pressure reading shortly after opening the controllable flow control valve (122) to admit liquid into the tank;closing the controllable flow control valve (122) if the reference pressure exceeds a first threshold pressure (Thl) and generating a first error message; andclosing the controllable flow control valve when the sensed pressure rises to a first predetermined amount (PAI) above the reference pressure (Pref).

15. The method of claim 14, comprising:obtaining a maximum liquid supply pressure reading (Pmax) before the controllable flow control valve (122) is opened; andclosing the controllable flow control valve (122) if the reference pressure (Pref) is within a second predetermined amount (PA2) of the maximum liquid supply pressure (Pmax), wherein the second predetermined amount (PA2) is greater than the first predetermined amount (PAI).

16. A computer program comprising code means which is adapted, when said program is run on a computer, to implement the method of any one of claims 13 to 15.

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