Fuel-pick-up device

Abstract

A fuel pick-up device for fitting to a fuel tank comprises a head 12 at a proximal end thereof, an elongate tubular constraint 10 extending from the head 12 towards a distal end of the device, a float 15 arranged for rising and falling with the level of fuel in the tank, and an elongate flexible pick-up tube 14 extending from the float 15 to a fuel outlet 13 at the head 12 of the device. An open end of the constraint 10 at the distal end of the device is closed by a shroud 23 which is displaceable axially of the constraint; The shroud 23 acts to radially constrain the position of the float 15 and alleviates any risk of the float member becoming trapped at the bottom of the tank during installation; Furthermore, the shroud 23 prevents persons from tampering with the float member.

Description

This invention relates to a fuel-pick-up device for use in drawing fuel from a tank or other reservoir. In conventional fuel tanks, the fuel is drawn from a point adjacent the bottom of the tank in order to enable the pick-up of fuel even when the level of fuel in the tank is low. However, a disadvantage of this arrangement is that any water and / or contaminants which have accumulated at the bottom of the tank can be drawn up with the fuel and fed to the apparatus which is being supplied with fuel. In most cases, fuel is being supplied to an internal combustion engine and any contaminant in the fuel could undesirably stop or damage the engine. GB2350337 discloses a solution to this problem in the form of a fuel-pick-up device having a float member arranged for rising and falling with the level of fuel in the tank, and a coiled flexible fuel pick-up tube having its distal end coupled to the float. The float member is arranged for vertical movement within a tubular constraint which encloses the float member and the flexible tube. In use, the float member ensures that the distal end of the pick-up tube is always adjacent the surface of the fuel in the tank. Accordingly, the risk of drawing up water and / or contaminants from the tank is alleviated. The tubular constraint in which the float member moves vertically comprises an elongate perforated tube which is closed at its lower end by a solid or perforated end wall. A disadvantage of this arrangement is that the length of the tubular constraint of the fuel-pick-up device needs to be accurate. On one hand, if the tubular constraint is too long, its lower end will abut the bottom of the tank and prevent the device from seating correctly in the fuel tank. On the other hand, if the tubular constraint is too short, the float member will not carry the distal end of the pick-up tube to the bottom of the tank, thereby reducing the volume of fuel that can be drawn from the tank. GB2482956 discloses an improved fuel-pick-up device of the aforementioned type which alleviates the above-mentioned problem and which comprises a tubular constraint which is open at its lower end. In use, the fuel-pick-up device operates in the same manner as the aforementioned fuel-pick-up device. However, the lower end of the tubular constraint is open thereby allowing the float member to partially extend below the tubular constraint when the level of fuel in the tank is low. In this way, a device with a slightly shorter filter or other member can be fitted into a tank to ensure that the device fits and to allow for manufacturing tolerances or deformations in the tank. However, when the level of fuel is low, the float member extends partially below the distal lower end of the tubular constraint, so that the volume of fuel that can be drawn from the tank is maximised. It will be appreciated that a fuel-pick-up device having a tubular constraint of a particular length can thus be fitted to tanks having a range of different depths. Since the distal end of the pick-up tube may be disposed outside the tubular constraint when the fuel in tank is low, the float member is provided with a filter arranged to filter the fuel being drawn up the pick-up tube. Fuel-pick-up devices of the type disclosed in GB2482956 have met with considerable commercial success, particularly as a retro-fit to the fuel tanks of vehicles and other machines used in industries where fuel contamination is problematic, such as the mining industry where any interruption to the operation of a machine by contaminated fuel can have a significant impact on the output and profitability of the company operating the machine. Typically, such devices are available in a range of different lengths: this allows devices to be supplied to customers for fitting themselves from standard stock items by selecting a device which is slightly shorter than the depth of the tank. The lower end of the tubular constraint is sufficiently close to the bottom of the tank to prevent the float member from displacing radially outwardly of the tubular constraint when the fuel level is low. However, a problem has arisen during the installation of fuel-pick-up devices in warm climates where heat causes the coiled flexible fuel pick-up tube to lose its resilience against straightening and to become more flexible. This allows the float member to undesirably extend fully out of the open end of the tubular constraint during installation and potentially into a radially displaced position where it can become trapped outside the constraint and held at the bottom of the tank. In these circumstances, the fuel-pick-up device will not operate as intended. Also, once the tank is filled with fuel, the buoyancy of the displaced float exerts extreme pressure on the fuel pick-up tube with the result that the tube may eventually sever on the sharp lower end of the tubular constraint. Another problem is that that there have been instances when the float member has been tampered with prior to installation, for example by persons trying to open the float members to see if there is anything of value inside. With the aforementioned problems in mind, we have now devised an improved fuel pick-up device. In accordance with the present invention, there is provided a fuel pick-up device having an elongate tubular constraint, a float disposed inside the tubular constraint and arranged for rising and falling with the level of fuel in a tank and an elongate flexible pick-up tube extending from the float member towards a first end of the tubular constraint, wherein an open opposite second end of the constraint is closed by a shroud which is displaceable axially away from the second end of the constraint. In use, the shroud retains the float member inside the constraint and prevents it from displacing radially of the open lower end thereof during installation. However, during installation the shroud displaces axially downwardly of the constraint into a position where it abuts the bottom of the tank, so that the float member is still able to extend unhindered below the distal lower end of the tubular constraint, so that the volume of fuel that can be drawn from the tank is maximised. The shroud also acts to prevent persons from tampering with the float member. The shroud may be freely fitted to the constraint, so that it displaces axially downwardly of the constraint under the influence of gravity during installation. However, in an alternative embodiment the shroud may be biassed axially away from the constraint. The shroud may be captively mounted to the constraint for movement between a retracted and an extended position. The shroud may comprise openings which allow fuel to flow unhindered into the distal end of the pick-up tube. The shroud may comprise a side wall slidably mounted to the constraint and a bottom wall. The constraint may comprise apertures which allow the flow of fuel into its interior, the constraint being disposed inside an outer sleeve which has openings and which acts to strengthen the constraint, the shroud being mounted end-to-end with the sleeve at the distal end of the device. The shroud may form a unit which is mounted to the second end of the constraint. In this manner, existing conventional fuel pick-up devices can be retro-fitted to form a device in accordance with the present invention. An embodiment of the present invention will now be described by way of an example only and with reference to the accompanying drawings, in which: Figure 1 is a longitudinal sectional view through a fuel-pick-up device in accordance with the present invention; Figure 2 is a perspective side view of the distal end of the fuel-pick-up device of Figure 1 when a shroud thereof is in its retracted position; Figure 3 is a perspective side view of the distal end of the fuel-pick-up device of Figure 1 when the shroud thereof is in its extended position; and Figure 4 is a perspective end view of the distal end of the fuel-pick-up device of Figure 1. Referring to the drawings, there is shown a fuel-pick-up device for fitting to a circular aperture formed in the top wall T1 of a fuel tank. The device comprises an elongate circular-section constraint 10 in the form of a metal sleeve provided with an array of apertures 11. The constraint 10 is closed at its first end by a flanged head 12, which is arranged for securing around its periphery to the edges of the aperture in the top wall T1 of the fuel tank. The second end of the constraint 10 is open. A rigid feed pipe 13 extends through the end cap 12, the lower end of the pipe 13 being connected to an elongate coiled flexible pick-up tube 14 of plastics material. The lower end of the flexible tube 14 is connected to a float member 15 by means of a tubular connector 20. The float member 15 is generally circular in section and is arranged to freely move vertically within the constraint 10 with the level of fuel in the tank. The float member 15 comprises a sealed upper chamber 16 which is filled with air and a separate bottom chamber 18 having bottom and side walls which are provided with apertures 19. The bottom chamber 18 comprises an outlet duct connected to the distal end of the flexible tube 14 via the connector 20. It will be appreciated that other types of float member may be utilised, such a float member of the kind disclosed in GB2472181. The constraint 10 is disposed inside an outer sleeve 21 which has openings 22 and which acts to strengthen the constraint 10. A shroud 23 is slidably mounted end-to-end with the sleeve 21 at the distal end of the device. The shroud 23 comprises an annular base 28 of the same diameter as the sleeve 21 and a pair of diametrically opposed legs 24 which extend towards the proximal end of the constraint 10. The proximal end of each leg 24 is provided with a pair of circumferentially-extending side arms 25 which embrace the constraint 10 and which are captively mounted between a pair of circumferentially-extending arms 26 provided on respective legs which extend from the distal end of the sleeve 21. The shroud 23 comprises a bottom wall 27 which extends across its annular base 28. In the example shown, the bottom wall comprises three radially extending arms having spaces therebetween which allow fuel to flow unhindered into the space inside the shroud 23. However, it will be appreciated that the bottom wall 27 may be of any form provided that it sufficiently closes the open distal end of the constraint 10, so as to retain the float member 15 at least partially inside the constraint 10. In use, during installation, the device is brought into a generally vertical orientation, whereupon its distal end is inserted thorough the circular aperture formed in the top wall T1 of the fuel tank. This causes the shroud 23 to displace axially downwardly of the constraint 10 under the influence of gravity. The float member 15 will also drop inside the constraint 10 but is prevented by the shroud 23 from displacing radially of the constraint 10. The device is inserted fully into the tank until its flanged head 12 abuts the top wall T1 of the fuel tank. The full insertion also causes the shroud 23 to abut the bottom wall T2 of the fuel tank, thereby causing the shroud 23 to displace axially upwardly of the constraint 10 until the head 12 is fully seated. In use, the float member 15 floats adjacent the surface of the fuel and fuel is drawn into the lower chamber 18 through the apertures 19 and along the flexible tube 14. The apertures 19 serve to filter the fuel and prevent sediment and other matter from being drawn up the flexible tube 14. The apertures 11 in the constraint 10 also serve to inhibit the ingress of contaminants and other matter into the space inside the constraint. As the level of fuel falls, the lower end of the float member 15 moves out of the constraint 10 as shown in Figure 1, thereby allowing fuel to be drawn to a level slightly below the constraint 10. In this manner, the volume of fuel in the tank can be maximised even if the constraint 10 does not reach fully to the bottom of the tank. An improved fuel-pick-up device in accordance with the present invention does not differ significantly in construction from the fuel-pick-up device of GB2482956 and comprises a shroud 23 which acts to radially constrain the position of the float member 15 and alleviates any risk of the float member 15 becoming displaced out of the constraint during installation. Furthermore, the shroud 23 prevents persons from tampering with the float member. In an alternative embodiment, the flanged head 12 is omitted and the constraint 10 is simply fixed directly to the tank. A bracket, support or mount may be provided for mounting the constraint 10 in position within the tank, for example through a side, top or bottom wall thereof.

Claims

1. A fuel pick-up device having an elongate tubular constraint, a float disposed inside the tubular constraint and arranged for rising and falling with the level of fuel in a tank and an elongate flexible pick-up tube extending from the float member towards a first end of the tubular constraint, wherein an open opposite second end of the constraint is closed by a shroud which is displaceable axially away from the second end of the constraint.

2. A fuel pick-up device as claimed in claim 1, in which the shroud is freely fitted to the constraint, so that it displaces axially downwardly of the constraint under the influence of gravity during installation.

3. A fuel pick-up device as claimed in claim 1, in which the shroud is biassed axially away from the constraint.

4. A fuel pick-up device as claimed in claim 1 or claim 2, in which the shroud is captively mounted to the constraint for movement between a retracted and an extended position.

5. A fuel pick-up device as claimed in any preceding claim, in which the shroud comprises openings.

6. A fuel pick-up device as claimed in any preceding claim, in which the shroud comprises a side wall slidably mounted to the constraint and a bottom wall.

7. A fuel pick-up device as claimed in any preceding claim, in which the constraint comprises apertures, the constraint being at least partially disposed inside an outer sleeve which has openings and which acts to strengthen the constraint, the shroud being mounted end-to-end with the sleeve at the distal end of the device.

8. A fuel pick-up device as claimed in any preceding claim, in which the shroud forms a unit which is mounted to the second end of the constraint.

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