WO2006080875A1

WO2006080875A1 - Motor vehicle

Info

Publication number: WO2006080875A1
Application number: PCT/SE2006/000052
Authority: WO
Inventors: Kim KYLSTRÖM; Peter Sperle; Vesa Hokkanen
Original assignee: Scania Cv Ab (Publ)
Priority date: 2005-01-25
Filing date: 2006-01-16
Publication date: 2006-08-03
Also published as: JP4397949B2; RU2007132157A; RU2388927C2; EP1851425B1; BRPI0606299B1; EP1851425A4; BRPI0606299A2; EP1851425A1; CN101107438B; JP2008528855A; SE0500187L; SE528145C2; CN101107438A

Abstract

A motor vehicle (1) comprising an engine (2) and a fuel system (3) for supplying the engine (2) with fuel is described. The fuel system (3) comprises a fuel tank (4), a fuel line (6) arranged between the fuel tank (4) and a feed line (5) connected to the engine (2), and a water separating filter (9) arranged on the fuel line (6) to separate water from the fuel, whereby the water separating filter (9) comprises a drain (10) for water. The drain (10) is connected to the fuel tank (4) by a drain line (11) in order to lead water from the drain (10) to the fuel tank (4).

Description

Motor vehicle

Technical field

The present invention relates to a motor vehicle with a fuel system and a water separating filter for separating water from fuel.

State of the art

Combustion engines in motor vehicles used in ordinary traffic are run on ordinary commercial fuel which may contain contaminants. Contaminants in the fuel may well damage the engine or at least impair its performance. The contaminants may be in particulate, gas or liquid form. Contaminants in fuel can impair engine performance to such an extent that the engine cannot run on it. It is known, for example, that even a small amount of water in diesel fuel can prevent a diesel engine from functioning. Particles in fuel damage the engine by causing increased wear or cause operational stoppage of the engine by obstructing fuel ducts in the engine.

Particles in the engine can be filtered out by particle filters well-known to specialists within the field. Particle filters become obstructed over time by the particles which they filter out, and therefore need changing at regular intervals. Water in fuel can be filtered out by a water-separating fuel filter.

US patent 5,355,860 describes a fuel system for diesel engines. The fuel system comprises a first fuel filter means which itself comprises a particle filter and a water separating filter. The water separating filter is provided with a valve for removal of water which accumulates within the water separating filter.

With the solution according to the US patent, the water has to be removed when the motor vehicle is not in motion, and suitable equipment has to be available when the water is removed. There is moreover no description of how the vehicle driver is to be made aware that water needs removing from the water separating filter. Summary of the invention

One object of the present invention is to provide a motor vehicle with a fuel system comprising a water separating filter, whereby the removal of water from the water separating filter is effected in an alternative manner as compared with the state of the art.

Another object of the present invention is to provide a fuel system for a motor vehicle, which fuel system comprises a water separating filter, whereby the removal of water from the water separating filter is effected in an alternative manner as compared with the state of the art.

A basic concept of the present invention is that the water separated from the fuel is returned to the fuel tank.

The invention relates primarily to a diesel-powered motor vehicle but is also applicable to other motor vehicles.

A first aspect of the present invention refers to a motor vehicle comprising an engine and a fuel system for supplying the engine with fuel, whereby the fuel system comprises a fuel tank, a fuel line arranged between the fuel tank and the engine, and a water separating filter arranged on the fuel line to separate water from the fuel, whereby the water separating filter comprises a water drain. The motor vehicle is characterised in that the water drain is connected to the fuel tank by a drain line to lead water from the water separating filter to the fuel tank.

A motor vehicle according to the invention is provided with an uncomplicated solution for storing the water which is separated in the water separating filter. The water is thus stored in the fuel tank, from which it can be drawn off when too much water has accumulated in the fuel tank. Drawing off is with advantage effected at a workshop where environmentally safe drawing off can take place. The motor vehicle may comprise a drain check valve arranged on the drain line to prevent flow of fuel from the fuel tank to the water separating filter. Such a drain check valve makes it possible to prevent fuel from being led in the wrong direction through the drain line. In such cases the drain check valve is so arranged that water can only be led from the water separating filter to the fuel tank and that flow of fuel from the fuel tank to the water separating filter via the drain line is prevented.

The motor vehicle may be so arranged that flow of water from the water separating filter is brought about by a pressure difference between the fuel tank and the water separating filter. A pressure difference can be brought about by relatively simple means, so this is an advantageous solution to the problem.

The motor vehicle may comprise a feed pump arranged on the fuel line between the water separating filter and the engine in order to supply fuel from the fuel tank to the engine when the feed pump is powered, and a first fuel check valve arranged on the fuel line between the water separating filter and the fuel tank, whereby fuel is allowed to flow past the feed pump in the direction from the engine towards the fuel tank when powering of the feed pump ceases, with the result that a negative pressure, relative to the pressure in the fuel tank, is created in the water separating filter when the feed pump is powered and that a positive pressure, relative to the pressure in the fuel tank, is created in the water separating filter when powering of the feed pump ceases. With such a motor vehicle, the result is a higher pressure in the water separating filter than in the fuel tank when the feed pump is switched off, with the result that water can be emptied from the water separating filter. The fuel system is with advantage so arranged that the flow of water continues until substantially all of the water has been emptied from the water separating filter.

The motor vehicle may comprise a return line between the feed line and the fuel tank, and a constriction arranged on the return line to bring about a higher pressure in the feed line than in the fuel tank when the feed pump is powered. Such a return line makes it easier to maintain an even flow of fuel to the feed line. The constriction makes it possible for the pressure in the feed line to be maintained. The motor vehicle may further comprise a pressure regulator arranged parallel with the feed pump. A pressure regulator is an easier means of maintaining an even pressure in the feed line.

The motor vehicle may also comprise a high-pressure pump arranged between the feed line and the engine. Such a high-pressure pump supplies fuel at high pressure to the engine. Depending on the type of engine, the feed pump may supply fuel at sufficiently high pressure directly to the engine, but cases where the fuel needs to be at very high pressure require a separate high-pressure pump. An example of such engines which need to be supplied with fuel at very high pressure is so-called "common rail" engines in which fuel at high pressure is distributed to each cylinder via so-called injectors arranged in each cylinder.

The motor vehicle may comprise a drain pump arranged on the drain line between the water separating filter and the fuel tank. This is an alternative way of leading water from the water separating filter to the fuel tank and does not depend on whether the feed pump is powered or not.

The motor vehicle may comprise a water level sensor for detecting the water level in the fuel tank, thereby preventing too much water from accumulating in the fuel tank, which might lead to the engine no longer being able to run. The water level sensor is with advantage connected to a warning indicator which warns the driver before the water level in the fuel tank starts becoming high. The warning indicator may for example be a warning lamp or a buzzer.

A second aspect of the present invention refers to a fuel system for supplying the engine of a motor vehicle with fuel. The fuel system comprises a fuel tank, a fuel line connected to the fuel tank and adapted to being connected to the engine, and a water separating filter arranged on the fuel line to separate water from the fuel, whereby the water separating filter comprises a water drain. The fuel system is characterised in that the water drain is connected to the fuel tank by a drain line to lead water from the water separating filter to the fuel tank.

A fuel system according to this second aspect of the present invention affords the same advantages as described above in relation to the motor vehicle according to the first aspect of the invention.

Features according to the dependent claims described above in relation to the motor vehicle according to the first aspect of the invention may also be combined with the fuel system according to the second aspect of the invention with the same advantages as there described.

Embodiments of the invention are described below with reference to the attached drawings.

Brief description of the drawings

Fig. 1 depicts schematically a motor vehicle according to an embodiment of the present invention.

Fig. 2 is a flowchart of a fuel system according to a first embodiment of the present invention.

Fig. 3 is a flowchart of a fuel system according to a second embodiment of the present invention.

Description of embodiments of the invention

In the following description of embodiments of the invention, similar items in the various embodiments are denoted by the same reference notations.

Fig. 1 depicts schematically a motor vehicle 1 according to an embodiment of the present invention. The motor vehicle 1 comprises an engine 2 and a fuel system 3 for supplying the engine 2 with fuel. The fuel system is depicted in more detail in Fig. 2. Fig. 2 is a flowchart of a fuel system 3 according to a first embodiment of the present invention. The fuel system 3 comprises a fuel tank 4, a feed line 5 and a fuel line 6 which is arranged to lead fuel between the fuel tank 4 and the feed line 5. The feed line 5 is connected to a high-pressure pump 7 adapted to supplying the engine 2 with fuel at high pressure. The fuel from the high-pressure pump is thereafter distributed in the engine in a known manner. The fuel system 3 further comprises a feed pump 8 arranged on the fuel line 6 and adapted to pumping fuel from the fuel tank 4 to the feed line 5.

A water separating filter 9 is arranged on the fuel line 6 upstream from the feed pump 8 and is adapted to separating water from fuel which is fed through the water separating filter 9. The water separating filter 9 may be of any of the types of water separating filter which are previously known or are invented in the future. As the function and construction of water separating filters 9 are previously known, no further description thereof will be given here. The water separating filter 9 comprises a water drain 10 to which a drain line 11 is connected. A drain check valve 12 is arranged on the drain line 11 and only allows flow of liquid such as water in a direction away from the water separating filter 9. A return line 13 is arranged between the feed line 5 and the fuel tank 4, and a constriction 14 is arranged on the return line 13. The constriction 14 results in a lower pressure downstream from the constriction. The drain line 11 is connected to the return line 13 at a connection point 15 downstream from the constriction 14 so that the return line 13 and the drain line constitute a common line between the connection point 15 and the fuel tank 4. A pressure regulator 16 is arranged parallel with the feed pump 8 and is adapted to regulating the pressure in the feed line 5. The fuel system 3 further comprises a particle filter 17 arranged on the fuel line between the feed pump 8 and the feed line 5 and adapted to filtering out particles from the fuel. A first check valve 18 is arranged on the fuel line 6 upstream from the water separating filter 9. A water level sensor 19 is arranged in the fuel tank 4 to measure the water level in the fuel tank 4. The water level sensor 19 is connected to a warning indicator 20 which gives a driver of the motor vehicle an indication if the water level is high. The warning indicator may be adapted to emitting a sound and/or a sonic signal and may for example take the form of a buzzer and/or a lamp. The fuel system 3 may also comprise a manual handpump 21 and a second check valve 22. The manual handpump 21 may be used for pumping fuel manually from the fuel tank 4.

The function of the fuel system 3 in Fig. 2 will now be described. During operation of the engine 2, the feed pump 8 pumps fuel from the fuel tank 4 to the feed line 5. The pressure in the water separating filter 9 will then be lower than atmospheric pressure, lower than the pressure in the fuel tank 4 and lower than the pressure in the feed line 5. The pressure in the feed line 5 is determined by the pressure regulator 16 as mentioned above. The pressurised fuel is led from the feed line 8 to the particle filter 17 and thence to the feed line 5 and the high-pressure pump 7 in order to be led on therefrom into the engine 2. Part of the pressurised fuel is led through the return line 13 and the constriction 14 back to the fuel tank 4. The pressure in the return line 13 downstream from the constriction 14 during operation is greater than or equal to atmospheric pressure. Water dissolved in the fuel is drawn into the water separating filter 9, in which it is separated and accumulates. The water separating filter may function according to any of the known principles for water separating filters or according to some principle which becomes known in the future.

When the feed pump 8 stops, which happens when the engine 2 is switched off, the pressure in the feed line will be equalised via feed pump 8, with the result that the pressure in the water separating filter 9 becomes greater than the pressure at the connection point 15 and in the fuel tank 4. The drain check valve 12 will then open and make it possible for water to pass from the water separating filter 9 through the drain check valve 12 to the fuel tank 4. Water will continue to pass through the drain line 11 so long as there is still any water in the water separating filter, at least if the fuel level in the fuel tank 4 is below the water level and the outlet end of the drain line is below the fuel surface in the fuel tank 4.

Starting the feed pump 8 gives rise to a negative pressure which is lower than atmospheric pressure in the water separating filter 9, with the result that the drain check valve 12 closes, thereby preventing water in the drain line 11 from passing back to the water separating filter 9.

After a period of use, the water level in the fuel tank 4 will be so high that the feed pump risks drawing only water, which would lead to operational malfunctions of the engine 2 or to the engine 2 stopping. However, the water level sensor 19 will detect a high water level in the fuel tank 4 and emit an indication via the warning indicator 20 before the water level in the fuel tank 4 has reached a dangerously high level.

Fig. 3 is a flowchart of a fuel system 3 according to a second embodiment of the present invention. Only the differences between the embodiment in Fig. 2 and the embodiment in Fig. 3 will be described. The fuel system in Fig. 3 has no manual hand pump. Moreover the particle filter is integrated with the water separating filter 9. In The fuel system in Fig. 3 a drain pump 23 is arranged between the water separating filter 9 and the fuel tank 4. A drain water sensor is arranged in the water separating filter 9. The drain pump 23 is adapted to being powered when the drain water sensor indicates a high water level in the water separating filter 9. Water can thus be led from the water separating filter to the fuel tank 4 irrespective of whether the feed pump 8 is running or not.

The invention is not limited to the embodiments described above but may be modified in many ways without departing from the spirit and scope of the invention.

Claims

1. A motor vehicle (1) comprising an engine (2) and a fuel system (3) for supplying the engine (2) with fuel, whereby the fuel system (3) comprises a fuel tank (4), a fuel line (6) arranged between the fuel tank (4) and a feed line (5) connected to the engine (2), and a water separating filter (9) arranged on the fuel line (6) to separate water from the fuel, whereby the water separating filter (9) comprises a drain (10) for water, characterised in that the drain (10) is connected to the fuel tank (4) by a drain line (11) in order to lead water from the water separating filter (9) to the fuel tank (4).

2. A motor vehicle (1) according to claim 1, whereby a drain check valve (12) is arranged on the drain line (11) in order to prevent flow of fuel from the fuel tank (4) to the water separating filter (9).

3. A motor vehicle (1) according to claim 1, whereby the motor vehicle is so arranged that flow of water from the water separating filter (9) is brought about by a pressure difference between the fuel tank (4) and the water separating filter (9).

4. A motor vehicle (1) according to claim 3, comprising a feed pump (8) arranged on the fuel line (6) between the water separating filter (9) and the engine (2) to feed fuel from the fuel tank (4) to the engine (2) when the feed pump (8) is powered, and a first fuel check valve (18) arranged on the fuel line (6) between the water separating filter (9) and the fuel tank (4), whereby fuel is allowed to flow past the feed pump (8) in the direction from the engine (2) towards the fuel tank (4) when powering of the feed pump (8) ceases, with the result that a negative pressure, relative to the pressure in the fuel tank (4), is created in the water separating filter (9) when the feed pump (8) is powered, and that a positive pressure, relative to the pressure in the fuel tank (4), is created in the water separating filter (9) when powering of the feed pump (8) ceases.

5. A motor vehicle (1) according to claim 4, further comprising a return line (13) between the feed line (6) and the fuel tank (4), and a constriction (14) arranged on the return line (13) to bring about a higher pressure in the feed line (5) than in the fuel tank (4) when the feed pump (8) is powered.

6. A motor vehicle (1) according to claim 4 or 5, further comprising a pressure regulator (16) arranged parallel with the feed pump (8).

7. A motor vehicle (1) according to any one of the foregoing claims, comprising a high-pressure pump (7) arranged between the feed line (5) and the engine (2).

8. A motor vehicle (1) according to any one of the foregoing claims, comprising a drain pump (23) arranged on the drain line (11) between the water separating filter (9) and the fuel tank (4).

9. A motor vehicle (1) according to any one of the foregoing claims, comprising a water level sensor (19) for detecting the water level in the fuel tank (4).

10. A fuel system (3) for supplying the engine (2) of a motor vehicle (1) with fuel, whereby the fuel system (3) comprises a fuel tank (4), a fuel line (6) connected to the fuel tank (4) and adapted to being connected to the engine (2), and a water separating filter (9) arranged on the fuel line (6) to separate water from the fuel, whereby the water separating filter (9) comprises a water drain (10), characterised in that the water drain (10) is connected to the fuel tank (4) by a drain line (11) in order to lead water from the water separating filter (9) to the fuel tank (4).