Device for detecting and removing water in a fuel tank

BACKGROUND TO THE INVENTION, AND STATE OF THE ART

The present invention relates to a device for detecting and removing water in a fuel tank according to the preamble of claim 1.

There is always risk that water will accumulate in fuel tanks. The accumulation may be due to condensation in the tank or to using fuel of inferior quality. The water, which is of higher density than the fuel, will accumulate on the bottom of the fuel tank. One way of removing the water from the fuel is to arrange a water-separating filter close to the fuel tank. When a vehicle undergoes repair or servicing, the water which has accumulated in the filter is removed. Another solution is to apply a permanent installation in the tank which makes it possible to both detect and remove water from the fuel tank. Such permanent installations are expensive.

US 4 728 924 refers to a portable device for detecting water in fuel tanks. The device comprises a probe adapted to being introduced downwards into a fuel tank, and a manoeuvring unit. A cable connects the probe to the manoeuvring unit. The cable comprises two electrical lines each connected to an electrode. The electrodes protrude from the probe at a distance from one another. When a voltage is applied between the electrodes, the electrical resistance in the region between the electrodes can be estimated. If the region is occupied by water, the electrical resistance will be considerably lower than if the region was occupied by fuel. The manoeuvring unit comprises a control element for activating the device and an alarm device which is activated if water is detected in the fuel tank. If water is detected in the fuel tank, measures have to be taken to evacuate the water from the fuel tank.

SUMMARY OF THE INVENTION

The object of the present invention is to propose a device which makes it possible to both detect and remove water in a fuel tank.

This object is achieved with the device of the kind mentioned in the introduction which is characterised by the features indicated in the characterising part of claim 1. Since fuel is of lower density than water, water accumulates on the bottom in the fuel tank. The device comprises detection means which monitor whether a measuring region contains fuel or water. The device comprises not only said detection means but also a tubular element. If the measuring region contains water, a negative pressure can be created in the tubular element so that the water situated in the fuel tank is drawn out and removed via the tubular element. The removal of the water continues with advantage until no more water is detected in the measuring region. The device thus comprises both detection means for detecting whether a fuel tank contains water and a tubular element with an inlet aperture through which it is possible to remove water in the fuel tank without the device having to be removed from the detecting position. The detection of water in a fuel tank can thus be followed by very rapid removal of the water in the fuel tank.

According to a preferred embodiment of the invention, said detection means are adapted to monitoring a parameter in a measuring region close to the first unit, and the inlet aperture of the elongate tubular element is arranged at the same or a lower height level above the bottom surface than height level of the measuring region above a bottom surface when the first unit is in a detecting position. The inlet aperture of the tubular element is here guaranteed to be situated in a region with water when the measuring region contains water. There is therefore no risk of fuel being drawn out through the tubular element. The measuring region is with advantage arranged relatively near to the bottom surface so that the fuel tank is substantially totally empty of water when fuel is detected in the measuring region.

According to a preferred embodiment of the invention, the tubular element comprises a connecting means which makes it possible to connect an external pump device to the outlet aperture. With advantage, the connecting means takes the form of a quick-fix connection. If water is detected in a fuel tank, the external pump device can therefore quickly and easily be connected to the tubular element and remove the water from the fuel tank. Substantially any desired types of external pump devices may be used. For example, a spray gun powered by compressed air may be connected to the tubular element to draw the water out from the fuel tank by ejector action. The external pump device may of course already be connected to the device when it monitors whether there is water in a fuel tank. Alternatively, the device may comprise an integrated pump connected to the tubular element. Such a pump may also be of any desired kind. If water is detected in a fuel tank, the pump may in that case be started substantially immediately to remove the water.

According to another preferred embodiment of the invention, the first unit comprises a contact region adapted to being applied in contact with the bottom surface in the fuel tank when the first unit is in a detecting position. The contact region has with advantage a shape substantially corresponding to that of the bottom surface. The contact surface should also be of relatively large extent on the bottom surface so that the first unit stands stably on the bottom surface when it is in a detecting position. The contact surface is thus adapted to being in contact with the bottom surface both when water is detected in the fuel tank and during a possible subsequent stage in which the water is removed from the fuel tank.

According to another preferred embodiment of the invention, the first unit comprises an internal space and at least one aperture which is adapted to making a communicating flow of fuel and water possible between the internal space and a surrounding in the fuel tank when the first unit is in a detecting position. If the inlet aperture of the tubular element is situated within the

internal space, said aperture will supply water to the internal space at the same rate as water is drawn out from the internal space. The water level in the internal space can thus substantially continuously be kept at the same level as the water level elsewhere in the fuel tank. If the measuring region is situated in the fuel tank, it may be situated within the internal space or externally to the internal space. If the measuring region is situated within the internal space but the inlet aperture of the tubular element is situated externally to the internal space, said aperture will cause the water level in the internal space to be substantially continuously kept at the same level as the water level elsewhere in the fuel tank. Said aperture comprises with advantage at least one portion situated at a lower level than measuring region when the first unit is in a detecting position. It is thus guaranteed that water can flow between the internal space and a surrounding in the fuel tank when water is pumped out through the tubular element. With advantage, the aperture has a lower portion at substantially the same height as the bottom surface in the fuel tank. The first unit will thus comprise no lower portion which would hinder a communicating flow of water between the internal space and a surrounding in the fuel tank along the bottom surface of the fuel tank. The inlet aperture of the tubular element is with advantage arranged close to the measuring region. Both the measuring region and the inlet aperture of the tubular element are preferably arranged in the internal space of the first unit. The device will therefore be of compact configuration.

According to an embodiment of the invention, said detection means comprise components adapted to measuring the electrical resistance in the measuring region. Water is electrically conductive, whereas fuels such as diesel oil and petrol conduct substantially no electric current. A parameter value which is related to the electrical resistance in the measuring region is therefore a very reliable indication as to whether the measuring region contains water or fuel. The measuring region may be defined by two electrodes arranged at a distance from one another. The current or the resistance may be measured in

the measuring region after the electrodes have been subjected to a specified voltage difference.

According to another preferred embodiment of the invention, said monitoring means comprise a control unit adapted to deciding on the basis of information about the value of said parameter as to whether the measuring region contains fuel or water. Such a control unit comprises with advantage suitable electrical components for this purpose. The control unit may comprise stored information which indicates the results corresponding to various parameter values, i.e. whether the measuring region contains water or fuel. The control unit is with advantage arranged in the second unit of the device, which is situated externally to the fuel tank. The device comprises preferably an indicating means adapted to indicating whether the measuring region contains fuel or water. Such an indicating means gives a user instantaneous information about whether the measuring region contains water or fuel. The indicating means may be a light-emitting diode or lamp which lights up if the fuel tank contains water. Other types of indicating means such as alarms or the like may also be used. The indicating means is with advantage arranged in the second unit of the device. Two or more indicating means may also be used to inform a user about the prevailing water level in a fuel tank, in which case the parameter values may be detected in two or more measuring regions arranged at different levels in the fuel tank.

According to an alternative embodiment of the invention, said detection means are adapted to monitoring a parameter in a measuring region which is situated close to the second unit. In this case, the measuring region is situated at a location external to the fuel tank. To detect whether the fuel tank contains water, the pump has therefore to be started and draw up water and/or fuel to the measuring region from a bottom surface in the fuel tank. The pump is kept activated so long as water is detected in the measuring region.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention is described below by way of example with reference to the attached drawings, in which:

Fig. 1 depicts a device, according to a first embodiment, for detecting and removing water from a fuel tank, Fig. 2 depicts a first unit of the device in Fig. 1 , Fig. 3 depicts schematically a second unit of the device in Fig. 1 and Fig. 4 depicts a device, according to a second embodiment, for detecting and removing water from a fuel tank.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

Fig. 1 depicts a fuel tank 1 arranged in a vehicle which is powered by a combustion engine. The fuel tank 1 is filled with fuel exemplified here as diesel oil 2. Water 3 which is of higher density than diesel oil 2 has accumulated on the bottom in the fuel tank 1. The water has accordingly a water level 3a which is related to the amount of water in the fuel tank 1. The development of combustion engines and more advanced engine controls is leading to increased sensitivity to water in the fuel. When a vehicle undergoes servicing or repair, checks are often carried out to detect whether the fuel tank 1 contains water, in which case the water is removed. Fig. 1 depicts a device which makes it possible to both detect water 3 in fuel tanks 1 and to remove the water 3. The device comprises a first unit in the form of a housing 4 adapted to being introduced downwards into the fuel tank 1 and a second unit in the form of a manoeuvring unit 5 adapted to being held by a user. The manoeuvring unit 5 comprises a button 5a for activating the device and an indicating means 5b in the form of a light-emitting diode or the like which lights up if water is indicated in the fuel tank 1. A tubular element such as a hose 6 extends between the housing 4 and the manoeuvring unit 5. The hose 6 has

an inlet aperture 6a situated within the housing 4 and an outlet aperture 6b situated close to the manoeuvring unit 5. The hose comprises a connecting means 6c which makes it possible to connect a pump device to the outlet aperture 6b of the hose. The pump device comprises in this case a pump 8, a first hose portion 9a and a second hose portion 9b. The first hose portion 9a is connected to the pump 8 at one end and has a connecting means 10 at an opposite end. The connecting means 10 is adapted to being connected to the connecting means 6c. The second hose portion 9b is connected to the pump 8 at one end and has an outlet aperture 11 at an opposite end.

Fig. 2 depicts the housing 4 in more detail. The housing 4 is made of a material which is of higher density than fuel. The housing 4 is made of a material which has electrically conductive characteristics and good corrosion resistance characteristics. The housing 4 may be made of stainless steel. The housing 4 has in this case a cuplike shape. The hose 6 extends into the housing via an aperture 4ci at one end of the housing. The housing 4 has at an opposite end a larger aperture 4c2 adapted to being directed downwards when the housing 4 is in a detecting position. The housing 4 comprises a contact region 4a which extends round the downward -directed aperture 4c2. The contact region 4a is adapted to being in contact with a bottom surface 1a in the fuel tank when the housing 4 is in a detecting position in the fuel tank 1. The contact region 4a has a shape corresponding to that of the bottom surface 1a so that the housing 4 can stand stably on the bottom surface 1a. The contact region 4a and the bottom surface 1a are with advantage planar. The housing 4 comprises an internal space 4b adapted to being filled with fuel and/or water when it is in a detecting position. The housing 4 comprises at least one aperture 4c ₃ which makes communication of fuel and/or water possible between the internal space 4b of the housing and a surrounding in the fuel tank 1. This aperture 4c3 extends right down to the contact surface 4a and therefore to the bottom surface 1a. Two electric cables 7a, 7b with insulating sheaths are arranged parallel with the hose 6 so that they have an extent between the housing 4 and the manoeuvring unit 5. One cable 7a comprises

an electrical connection 7ai to the housing 4. The other cable 7b comprises an electrode 7bi or the like arranged at a predetermined height hi above the contact region 4a of the housing. Applying a voltage between the electric cables 7a, 7b will cause a voltage difference between the housing 4 and the electrode 7bi. The electrical resistance can therefore be estimated in a measuring region 12 which extends between the housing 4 and the electrode 7bi. If the measuring region 12 contains water, the electrical resistance will be considerably lower than if the measuring region 12 contained fuel. The measuring region 12 is situated at the height hi above the bottom surface 1a when the housing 4 is in a detecting position. The inlet aperture 6a of the hose is situated at a height level hi2 above the bottom surface 1a when the housing 4 is in a detecting position. The inlet aperture 6a is situated at a lower height level hi2 than the height level hi above the bottom surface 1a.

Fig. 3 depicts schematically the most relevant components of the manoeuvring unit 5. The manoeuvring unit 5 comprises an electrical control unit 13. The electrical control unit 13 is activated by a first circuit comprising said circuit- breaker 5a which is adapted to being operated by a user and a voltage source 5c which may be a battery. The electrical control unit 13 is connected to a second circuit which comprises the indicating means 5b. The electrical control unit 13 is also connected to the electric cables 7a, 7b. The electrical control unit 13 comprises components which make it possible to apply a specified voltage in the electric cables 7a, 7b. Applying a voltage to the electric cables 7a, 7b creates an electrical circuit whereby the current and/or the electrical resistance in the measuring region 12 can be estimated.

During vehicle servicing or repair, the device is used for detecting and removing any water in the vehicle's fuel tanks 1. When a fuel tank 1 has been opened, the housing 4 is introduced downwards into the fuel tank 1. As the housing 4 is made of a material which is of higher density than fuel 2 in the fuel tank 1 , the housing 4 sinks quickly down to the bottom in the fuel tank. The housing 4 may be provided with undepicted further apertures for evacuation of

air from the internal space 4b. When the contact region 4a of the housing comes into contact with the bottom surface 1a, the housing 4 has reached a detecting position in the fuel tank 1. As the housing comprises at least one aperture 4c3 which allows a communicating flow between the internal space 4b of the housing and the rest of the fuel tank, the result is the same water level 3a in the internal space 4b as elsewhere in the fuel tank. When the housing 4 has reached the detecting position, the circuit-breaker 5a is pressed in so that the power source 5c is connected to the control unit 13. The control unit 13 supplies the electric cables 7a, 7b with voltage. A voltage difference is thus created between the housing 4 and the electrode 7bi. One of the cables 7a, 7b may be earthed. The measuring region 12 is situated in the region where the distance between the housing 4 and the electrode 7bi is shortest. Water 3 is a good conductor of electric current, whereas diesel oil is substantially not electrically conductive. The control unit 13 can therefore estimate whether an electrical current occurs in the measuring region 12, i.e. between the housing 4 and the electrode 7bi. If the control unit 13 receives information which indicates that substantially no electrical current occurs in the measuring region 12, it may be found that the measuring region contains fuel which is of high resistivity. If the control unit 13 receives information which indicates that an electric current occurs in the measuring region 12, it may be found that it contains water which is of low resistivity, in which case the control unit 13 activates the indicating means 5b. A user thereby receives a quick indication as to whether the fuel tank 1 contains water 3 in the measuring region 12, in which case the water level 3a in the fuel tank 1 is at an unacceptable level.

In cases where such an unacceptable water level 3a is indicated, the pump device is connected, by the connecting means 6c, 10, to the device. The connecting means 6c, 10 are with advantage of a quick-fix connection type. Thereafter the user activates the pump 8 so that a negative pressure is created within the hose 6. As the inlet aperture 6a is situated at a lower level than the measuring region 12 which contains water, it is guaranteed that only water will be drawn into the hose 6 via inlet aperture 6a and out from the fuel

tank 1 via outlet aperture 11. With advantage, the control unit 13 measures continuously the current and/or the electrical resistance in the measuring region 12 when the pump 8 is activated. The water 3 drawn out from the internal space 4b is continuously replaced by water which flows in through the aperture 4c3, thereby maintaining the same water level 3a in the internal space 4b of the housing as elsewhere in the fuel tank 1. When the control unit 13 receives information which indicates that the electrical resistance suddenly increases markedly in the measuring region 12, it may be found that the water level 3a has sunk to a lower level than level hi of the measuring region. The measuring region 12 will then contain diesel oil 2. The control unit 13 will deactivate the indicating means 5b so that the user receives an immediate indication that the water level 3a in the fuel tank 1 has now sunk to an acceptable level. The user will switch off the pump 8 so that there is no risk of fuel being pumped out. The device according to the invention thus both provides very rapid and reliable detection of the presence of an unacceptable amount of water 3 in the fuel tank 1 and effects removal of the water so that the water level 3a in the fuel tank 1 sinks to an acceptable value.

Fig. 4 depicts an alternative embodiment of the invention. In this case the device comprises the pump 8. The pump 8 is here arranged upstream of the manoeuvring unit 5, but might equally well be arranged downstream of, or in, the manoeuvring unit 5. With this device there is therefore no need for any external pump to be connected. In this case, electrodes 7ai, 7bi are so arranged that they extend into a passage for fuel and/or water in the manoeuvring unit 5. When a voltage is applied between the electrodes 7ai, 7bi the electrical resistance can be estimated in a measuring region 12 in the passage. To detect whether the fuel tank 1 contains water, the pump 8 has in this case to be started first. The fuel and/or the water is/are drawn into the hose 6 via its inlet aperture 6a situated close to the bottom surface 1a of the fuel tank. The fuel and/or the water thus reach the measuring region 12 in the manoeuvring unit 5. On the basis of information about the electrical resistance in the measuring region 12, the control unit 13 can decide whether the

measuring region 12 contains water or fuel. The pump 8 is kept activated so long as water is detected in the measuring region 12. As soon as fuel is detected in the measuring region 12, the pump 8 is switched off. The pump 8 may be switched off automatically by the control unit 13 or manually by a user.

The invention is in no way limited to the embodiments depicted in the drawings but may be varied freely within the scopes of the claims. A device with an integrated pump 8 may have a measuring region 12 close to the housing 4 and a device with a connectable pump 8 may have a measuring region 12 close to the manoeuvring unit 5. In the embodiment depicted in Fig. 2, the measuring region 12 and the hose inlet aperture 6a are situated within the internal space 4b of the housing, but it is possible to arrange the measuring region 12 or the hose inlet aperture 6a in the fuel tank at a location external to the housing 4. The first unit 4 need not necessarily be provided with an internal space 4b, in which case both the measuring region 12 and the hose inlet aperture 6a would be arranged externally to the first unit.