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(11) | EP 2 078 845 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Preventing water ingress in an internal combustion engine |
| (57) Apparatus for use with a fuel tank (1) for preventing water from a fuel tank from
entering an internal combustion engine through a fuel line (17) connecting the fuel
tank (1) and the engine, the apparatus comprising: a fuel filter (3) arranged to be
connected within the fuel line (17); means (15) for conveying fuel and any water entrained
therein from the fuel tank to the filter; and means (19) for conveying any water which
has accumulated in the fuel filter (3) back to the fuel tank (1) so as water collects
at the bottom of the filter (3) it is able to be withdrawn from the filter (3) and
to pass along the passage (19) back into the fuel tank (1) where there is a much greater
capacity to store excess water.
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BACKGROUND OF THE INVENTION
[0001] This invention relates to an apparatus and method for preventing water from entering and internal combustion engine through a fuel line. Further, the invention extends to a system and to a diesel combustion engine comprising said apparatus.
[0002] It is commonly known for vehicles or other automotive systems with an internal combustion engine to comprise at least a primary filter of medium efficiency (i.e. which removes 95-98% of particles in the range of 10 to 50 microns) and sometimes a secondary fuel filter of a relatively higher efficiency (i.e. which removes 95-98% of particles in the range of 3 to 10 microns). Both filters separate undesirable particles from the fuel before it passes to the fuel injection equipment (FIE).
[0003] In diesel engines, the fuel acts as a lubricant to reduce friction during engagement of the surfaces of the components of the engine, e.g. highly polished valve seats and fine nozzle orifices. However, if water droplets (free water) are present in the fuel when it passes through the FIE, the momentum of the water entrained in the fuel will cause the surfaces to wear. Further, a relatively large amount of compression acts on the components during operation of the engine but, since water is incompressible, any water present within the FIE may damage the surrounding component surfaces. Therefore, it is extremely undesirable to allow free water to enter the FIE as its presence may significantly shorten the lifespan of the engine.
[0004] A known system is illustrated in Figure 1 and is described below in the detailed description.
[0005] In many known systems the primary and/or secondary fuel filter also serves to remove the majority of the free water from the fuel before it is drawn into the FIE.
[0006] When the filter receives fuel and emulsified water, the medium within the filter serves to separate the water from the fuel, and water droplets settle under gravity at the bottom of the filter. This water can be drained manually by removing a plug in the filter, but this method of removing water from the filter is not ideal as it will not always prevent water from entering the FIE. For example, when the filter receives a large volume of free water from the tank, the filter does not have sufficient capacity or means to separate the water from the fuel, and at least a portion of the water will be passed into the FIE before the water is drained from the filter. A situation where water is pumped into the FIE is undesirable for the above-described reasons.
[0007] Known systems include a sensor, housed within the filter, which detects when the water reaches a predetermined level (normally the level is set at a point where the water storage facility in the filter is nearing capacity) and indicates, via a warning signal, when that has occurred. However, there is an undesirable time delay between when the sensor generates the warning signal and when the filter can in practice be drained of water: when the driver sees the warning signal (typically an icon is illuminated on a dashboard) he will not stop immediately but will wait until there is a convenient place to stop or he has reached his destination. In such time it is possible that water has been taken into the FIE. Further, when the engine is finally stopped water present in the FIE will begin to corrode the internal surfaces of the pump and injectors.
[0008] Simply increasing the filter's retention volume so as to allow a greater volume of water to be stored within the filter does not provide a useful solution to these problems; it delays the occurrence of the problems but it does not prevent them.
[0009] As a further consideration, increasing the water retention capacity of the filter inevitably increases the size of the filter, and this will affect the configuration of the filter within the engine. It is generally not advantageous to increase the size of a component within an engine, since, the resulting space requirement can complicate the configuration of other engine components.
[0010] Accordingly, the invention arises from the Applicant's efforts to provide a water separation apparatus and system which prevents water from being drawn into the FIE. It is further intended to achieve these objectives whilst providing a system which does not suffer from the disadvantages of the prior art.
SUMMARY OF THE INVENTION
[0011] The inventor has recognised that overcoming the problems mentioned above is possible by providing apparatus for use with a fuel tank for preventing water from a fuel tank from entering an internal combustion engine through a fuel line connecting the fuel tank and the engine, the apparatus comprising: a fuel filter arranged to be connected within the fuel line; means for conveying fuel and any water entrained therein from the fuel tank to the filter; and means for conveying any water which has accumulated in the fuel filter back to the fuel tank.
[0012] Advantageously, therefore, as water collects at the bottom of the filter it is able to be withdrawn from the filter and passed along the passage back into the fuel tank, where there is a much greater capacity to store excess water. As a result there is no accumulation of water in the filter and the system does not rely on a manual system to drain the water.
[0013] The apparatus further comprises means for pumping fluid from the fuel tank into the filter. The pumping means maybe a pressure pump or a suction pump.
[0014] Further, the pumping means may be located anywhere in the fuel line provided the necessary pressure can be imparted to the filter. More preferably, the pumping means is located in the fuel tank.
[0015] In a preferred embodiment, the passage comprises a flow controlling means. This provides the advantage that the rate at which fuel (when no water is present in the filter) and water (when water is present in the filter) flows back into the fuel tank is controlled.
[0016] In one embodiment the flow controlling means is a portion of the passage which is constricted. Advantageously, the constricted portion restricts the rate at which fluid may flow back into the tank.
[0017] Alternatively, the flow-controlling means may be a valve, and the width of the passage is not reduced in size and the flow rate of the respective fluids can be accurately controlled. For example, the valve can be electronically controlled by the engine control module (ECM) of the vehicle.
[0018] The flow-controlling means may advantageously comprise a one-way valve. This type of valve provides the advantage of permitting water to pass from the filter to the tank via the passage when the pump is non-operational. Hence, when the driver has switched off the engine of the vehicle, the passage will continue to carry water from the filter into the tank. As result, when the engine is re-started, there will be no water remaining in the filter and the risk of free water being taken up into the FIE is reduced. The one-way valve also prevents air being drawn into the filter when the engine is in operation.
[0019] The apparatus preferably comprises the tank. More preferably, a water sensing means is located within the fuel tank. Advantageously, the water sensing means is positioned below the level at which fuel is able to be drawn from the tank. An unusually large influx of water into the fuel tank will not usually be sufficient to raise the water level from beneath that of sensor to the 'pick-up level'. In the event that water activates the sensor, a signal is generated before the water is pumped into the filter, and most importantly, before the volume of water accumulates in the filter and is pumped to the FIE.
[0020] It is preferred that when activated, the water sensor generates a signal and transmits it to an electronic control module and/or a driver's visual display. This is particularly useful as, during maintenance of the vehicle, the service company can check the ECM to find relevant data for cross-checking with fault diagnosis and warranty claims.
[0021] It is apparent that the invention provides the further advantage that no drain is necessary in order for water to be efficiently prevented from being taken into the FIE.
[0022] However, in one embodiment of the invention the fuel tank is provided with means for draining water therefrom. The draining means, for example a plug, is located within one of a wall and base of the fuel tank and temporary disengagement of the plug from the base permits water to drain from the tank. The removal of the plug could be undertaken manually. However, it is envisaged that a plug assembly could be used in which the opening and closing mechanism is partially or fully automated. For example, in a fully automated process the plug would be directly activated or opened in response to a signal from the sensor which indicates that there is an undesirable amount of water in the tank. The plug would then automatically close after a specific pre-determined timed period or when no further signal is received from the sensor after a set time period. These signals and responses may be coordinated directly or indirectly by the ECM. Alternately, an independent signal initiated by the driver, i.e. a manually operable switch, which may be in response to the first signal on his dash board, could be generated to cause the plug to open and/or close.
[0023] It is intended that the invention provides an apparatus having a combination of any of the individual features described in the above embodiments.
[0024] The invention further resides in an apparatus for preventing water from a fuel tank from entering an internal combustion engine through a fuel line connecting the tank and the engine, the apparatus comprising: a fuel tank; means for sensing the presence of water within the fuel tank; and means, operable in response to the sensing means, for draining the water from the fuel tank.
[0025] The invention extends the apparatus as described above in combination with an internal combustion engine.
[0026] The invention also encompasses a method for preventing water from a fuel tank from entering an internal combustion engine through a fuel line via a fuel filter, the method comprising:
conveying any water accumulated within the filter back to the fuel tank.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order that the invention may be more readily understood, specific embodiments of the invention will now be described with reference to the accompanying drawings in which:
Figure 1 illustrates a typical water separation system of the prior art;
Figure 2 is a schematic diagram of one embodiment of the present invention;
Figure 3 is a schematic diagram of another embodiment of the present invention; and
Figure 4 is a schematic diagram of a further embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0028] Where dimensions are given in this specific description, they are given only for the purpose of illustration and are not intended to limit the invention in its broadest sense.
[0029] A typical system of the prior art is illustrated in Fig 1 in which the pathways of fluid communication are shown between a fuel tank 1, a fuel filter 3 and fuel injection equipment (FIE) 5.
[0030] Typically, the filter 3 is present either within a diesel fuel tank 1 or located, as shown in this example, along the fuel line between the fuel tank 1 and the FIE 5.
[0031] Provided that the surface of the fuel is above a critical 'pick-up level' within the tank 1, a feed pump 15 within the fuel tank 1 draws fuel from the tank 1 and pumps it into the filter 3 via a feed line 17.
[0032] The fuel tank 1 receives water from a variety of sources within the engine, for example, via the filler neck 13. Over time, the volume of water, which is more dense than diesel fuel, increases within the base of the fuel tank 1. Water within the fuel tank 1 normally resides under the fuel, lower than the pick-up level and will not be drawn up by the pump 15. However, the fuel, which may contain emulsified water, enters the filter 3 to be purified before it is drawn into the FIE 5.
[0033] The filter 3 comprises a type of chemically-treated filter medium 7 which repels water. As the fuel passes through the filter medium 7 the emulsified water forms droplets 9 and is substantially prevented from passing therethrough. The fuel travels through the medium 7 and up through the filter 3 and is pumped into the FIE 5. The water droplets 9, having a greater density than incoming diesel fuel, settle under gravity and collect in a bottom part 3a of the filter 3.
[0034] When water accumulates in the bottom part 3a of the filter 3, it may be removed by temporarily disengaging a drain/plug 11 located in a bottom or side wall of the filter 3. However, this system is not always effective in preventing water from being pumped from the filter 3 into the FIE 5.
[0035] If the volume of water within the fuel tank 1 build-ups very quickly, e.g. by a relatively large influx of water to the tank 1 through the neck 13, the water level may rise above the critical pick-up level and the water will be pumped in a concentrated form into the filter 3. The result is that the filter 3 receives an unusually large amount of free water via feed line 17. Such a volume of free water cannot be separated, stored or removed efficiently from the filter 3, and therefore at least a portion of the free water will be passed into the FIE 5 before the plug 11 can be removed and water is drained from the filter 3.
[0036] Referring now to Fig 2, which is a schematic diagram of a first embodiment of the invention. The pathways of fluid communication are again shown between a fuel tank 1, a fuel filter 3 and FIE 5. In particular, provided that the surface level of fuel within the tank 1 is above a critical 'pick-up level' within the tank 1, a feed pump 15 housed within the fuel tank 1 will pump fuel from the tank 1 via a feed line 17 to the filter 3.
[0037] The fuel passes through a chemically treated filter medium 7 within the filter 3 and, on one side of the filter, the emulsified water separates out of the fuel into water droplets 9. The fuel continues to travel up through the filter 3 and is pumped into the FIE 5. The water droplets 9, having a greater density than the diesel fuel, settle under gravity, and collect in a bottom part 3a of the filter 3.
[0038] A passage 19 connects, with a first end, to the base 17 of the filter 3 and, with a second end communicates with the fuel tank 1. As water collects at the bottom 3a of the filter 3 it flows out of the filter 3 and passes into passage 19. When no water has collected in the base 17 of the filter 3, fuel will flow out of the filter 3 and pass into this passage 19. A valve 23 is located within the passage 19 and controls the rate at which fuel (when no water is present in the filter) and water (when water is present in the filter) flow back into the fuel tank 1.
[0039] The tank 1 is further provided with a sensor 25 which detects when the water in the tank 1 has risen to a predetermined level (which is lower than the 'pick-up level' at which level fuel is pumped by the feed pump 15 into the filter 3). The water sensor 25 is positioned sufficiently below the 'pick-up level' so that an unusually large influx of water into the fuel tank 1 would not necessarily be sufficient to raise the water level in the tank 1 from beneath the level of sensor 25 to above the 'pick-up level'. In the event that the water in the tank 1 rises above the level of the sensor 25, a signal is generated before the water is pumped into the filter 3, and more importantly, before water in the filter 3 is pumped into the FIE 5. When the sensor 25 is activated by water it will transmit a signal to the vehicle's engine control module (ECM) so that a record is made each time the water rises close to the 'pick-up level'. Either as a result of a second signal, or in response to the first signal, an icon on the driver's visual display (dashboard) is illuminated, indicating to the driver that this has occurred.
[0040] The fuel tank 1 has a much larger storage capacity than that of the filter 3. Hence, the tank 1 is able to accommodate a much larger volume of water than is possible in the filter 3.
[0041] The fuel tank 1 includes a plug or plug assembly 27 installed in the tank base 29 which can be temporarily disengaged from the tank base 29 to allow water to be drained. When the driver has been alerted that the water level in the tank 1 has risen to at least the level of the sensor 25, he may choose to manually drain the excess water in the tank 1. However, if he fails to act immediately, and water is taken up by the pump 15 and fed into the filter 3, it is not an immediate problem because the water will flow into passage 19 and then be fed back to the tank 1. In the first instance, water will not begin to accumulate in the filter 3. To prevent water from being further pumped into the filter 3, the plug 27 is automatically opened and/or closed in response to an electronic signal from the sensor 25 or an electric signal from the dashboard which may be routed from the ECM.
[0042] Turning to Figure 3, broadly the same apparatus of the invention is arranged as described above in relation to Figure 2. However, there are a number of subtle differences. In this embodiment the pump 15 is shown located in a feed line 31 between the filter 3, and the FIE 5. Provided the pump 15 provides enough pressure in the filter 3 the fuel (and water, if applicable) is caused to rise through the feed line 17 and enter the filter 3. The flow control means is a one-way valve 33 which permits water to pass through and along passage 19 to the tank 1.
[0043] Figure 4, displays broadly the same layout of apparatus as described above in relation to Figure 2. However, the feed line 17 conveys the fuel from the tank 1 to the filter 3 at a location above the filter medium 7. In this arrangement the medium 7 is configured differently i.e. a different geometric mesh positioned lower within the filter 3. Hence, the droplets of water 9 form on a clean side of the filter medium 7 (rather than on the dirty side as in Figure 2). However, the droplets 9 are still diverted to the base 3a of the filter 3 and are passed through passage 19 back to the tank 1 as previously described,
1. Apparatus for use with a fuel tank for preventing water from a fuel tank from entering
an internal combustion engine through a fuel line connecting the fuel tank and the
engine, the apparatus comprising:
a fuel filter arranged to be connected within the fuel line;
means for conveying fuel and any water entrained therein from the fuel tank to the filter; and
means for conveying any water which has accumulated in the fuel filter back to the fuel tank.
2. The apparatus of Claim 1, further comprising means for pumping the fuel from the fuel
tank to the fuel filter.
3. The apparatus of Claim 2, wherein the pumping means is located within the fuel tank.
4. The apparatus of Claim 2 or Claim 3, wherein the pumping means is a suction pump.
5. The apparatus of Claim 2 or Claim 3, wherein the pumping means is a pressure pump.
6. The apparatus of any one of Claims 1 to 5, wherein the water conveying means comprises
a means for controlling flow.
7. The apparatus of Claim 6, wherein the means for controlling flow comprises a constriction
within the water conveying means.
8. The apparatus of Claim 6 or Claim 7, wherein the means for controlling flow is a valve.
9. The apparatus of Claim 8, wherein the valve is a one-way valve.
10. The apparatus of Claim 1, further comprising the fuel tank.
11. The apparatus of any Claim 10, further comprising a water sensing means within the
fuel tank.
12. The apparatus of Claim 11, wherein the sensor is positioned, in use, in the tank below
the level at which the fuel line is connected to the fuel tank.
13. The apparatus of Claim 11 or Claim 12, wherein the sensor is arranged to be electrically
connected to at least one of: a driver's visual display and an engine control module.
14. The apparatus of any one of Claims 10 to 13, wherein the fuel tank further comprises
means for draining water therefrom.
15. The apparatus of Claim 14, wherein the draining means is located within one of a wall
and base of the fuel tank.
16. The apparatus of Claim 14, wherein the draining means is arranged to be controlled
by a signal from at least one of: a water sensor; a manually operable switch; and
an engine control module.
17. A method for preventing water from a fuel tank from entering an internal combustion
engine through a fuel line via a fuel filter, the method comprising:
conveying any water accumulated within the filter back to the fuel tank.
18. The method of Claim 17, further comprising controlling the flow of the water back
to the filter.
19. The method of Claim 17 or Claim 18, further comprising detecting the presence of the
water above a predetermined level within the fuel tank.
20. The method of Claim 19, further comprising generating a signal in response to a positive
detection of water above the predetermined level and transmitting the signal to a
driver's visual display.
21. The method of Claim 19, further comprising generating a signal in response to a positive
detection of water above the predetermined level and transmitting the signal to an
engine control module (ECM).
22. The method of any one of Claim 19, further comprising draining water from the fuel
tank in response to a positive detection.
23. Apparatus for preventing water from a fuel tank from entering an internal combustion
engine through a fuel line connecting the tank and the engine, the apparatus comprising:
a fuel tank;
means for sensing the presence of water within the fuel tank;
means, operable in response to the sensing means, for draining the water from the fuel tank.
24. The apparatus of Claim 23, wherein the sensing means is positioned, in use, in the
tank below the level at which the fuel line is connected to the fuel tank.
25. The apparatus as claimed in any one of Claims 1 to 16 or Claims 23 or 24, in combination
with an internal combustion engine.