SE538892C2 - A method of a processing unit in connection with water separation in a fuel filter, and said processing unit - Google Patents

Abstract

A method in a processing unit (2) for a fuel system (4) for an internal combustion engine (6), wherein the fuel system (4) comprises a fuel tank system (8) with at least one main tank (9) intended for fuel, and a fuel filter (16) through which the pumped fuel is intended to pass, the fuel filter (16) comprises a water separating part intended to separate water from the fuel, and a measuring unit (18) arranged in connection with the fuel filter (16), and the processing unit (2) comprises a memory unit (24) and an analysis unit (26). The method comprises the steps of: - performing, with the measuring unit, measurements of one or more parameters related to the separated water; - determining measured values for said parameters; - generating a measurement signal comprising said measurement values; - receiving said measuring signal in the processing unit; - storing said measured values in the memory unit; - analyzing said stored measured values in the analysis unit using a set of predetermined rules related to the function of the fuel filter and / or the water content of the fuel; generating an indication signal in dependence on said analysis, the indication signal comprising information related to the function of the fuel filter and / or the water content of the fuel. (Figure 1)

Description

TitleA method for a processing unit in connection with water separation in a fuel filter, and said processing unit.

FIELD OF THE INVENTION The present invention relates to a method in connection with a processing unit, and a processing unit, according to the preambles of the independent claims. The processing unit and the method according to the invention are in particular adapted to be applied in connection with vehicles, for example trucks and buses, but can also be used in other applications where internal combustion engines are used, for example on ships and in industry.

Background of the Invention Internal combustion engines burn an air / fuel mixture in a plurality of cylinders to drive pistons which generate a driving torque. Air is sucked into a suction pipe through an inlet and fuel is then injected into the suction pipe or directly into the cylinders (direct injection) to create the air / fuel mixture. A fuel system is used to adjust the fuel flow injected to obtain a desired air / fuel mixture to the cylinders. The fuel system often includes one or more fuel tanks, fuel pumps, fuel filters and fuel injectors. For example, a single-pressure fuel pump can draw the fuel from a fuel tank, pressurize the fuel and feed low-pressure fuel to an injector or single-pressure fuel pump.

A high-pressure fuel pump further increases the pressure and feeds the fuel to one or more injectors.

With today's high pressures and sensitive tolerance bands on injection systems, this is a requirement for water separation in the fuel system's low pressure circuit in connection with filtration. An example of a fuel system with a fuel filter is described in the following documents.

WO-2012/023638 relates to a device for protecting an engine against inflow fuel with too high a water content by lowering the speed of the engine including content in the fuel is detected. More specifically, the device comprises a single sensor for detecting the water content of the fuel. The sensor generates a single detection signal depending on the measurements and a control signal generates a depression of the speed depending on the detection signal. Furthermore, the driver can get an indication if the water separation does not work as intended.

As the requirements increase both for long service intervals on fuel filters and high efficiency on water separation, it is not always possible that these two requirements can be met. It is common today to drive until the fuel filter is clogged, and then too long ago the water separation is at an unacceptable level due to the degradation of the filter. This means that aqueous fuel has been driven into the injection system with initial damage as a result.

The object of the present invention is to improve the current fuel system by previously obtaining an indication of the function of the fuel filter and also to obtain an indication of the water content of the fuel.

SUMMARY OF THE INVENTION The above objects are achieved by the invention defined by the independent claims.

Preferred embodiments are defined by the dependent claims. The present invention is preferably applicable in a fuel system of a type which may be called controllable low pressure system where the fuel pump is controlled independently of the engine. The present invention improves the ability to detect and diagnose degraded water separation from the fuel in the fuel filter. Another advantage of the invention is that it provides an opportunity to detect early on whether the fuel has an unacceptably high water content.

According to one embodiment, the invention allows the system to optimize itself more adaptively with respect to the water separation by lowering the flow / pressure on the fuel pump so that the water is better separated over time.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart schematically showing the method of the present invention.

Figure 2 is a block diagram schematically illustrating the present invention. Figure 3 is a block diagram schematically illustrating an embodiment of the present invention.

Figure 4 is a schematic view of a vehicle in which the present invention has been implemented.

Figure 5 is a graph illustrating aspects of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION In the figures, details with the same or similar function and design have consistently been given the same reference numerals.

Initially, a general description of a fuel system where the invention is applicable follows, followed by a detailed description of preferred embodiments of the invention with reference to the accompanying drawings.

In many of today's vehicles, the fuel pump is arranged in connection with the engine and sucks up the fuel. Often the fuel pump is mechanically connected to the engine and is driven by the engine's drive shaft. In another type of fuel system pre-combustion engines, the fuel pump is instead arranged in connection with the main tank and pressurizes the fuel via fuel lines to the engine. In this type 4 of fuel system, the fuel pump is often electrically, pneumatically or hydraulically driven, and is driven independently of the drive shaft of the internal combustion engine.

The present invention is particularly applicable to this second type of fuel system, i.e. where the fuel pump is arranged adjacent to the main tank and pushes the fuel to the engine. The fuel pump is, for example, electrically, pneumatically or hydraulically driven independently of the drive shaft of the internal combustion engine.

According to a variant, a smaller transfer pump is arranged to pump fuel from one or more main tanks (large tanks) to a smaller tank, often called a transfer tank. Adjacent to the smaller tank is a main pump arranged to then pump the fuel further from the smaller tank to the engine, via for example a high pressure pump which is often arranged in connection with the engine.

One reason for arranging a smaller tank, and pumping the fuel via the dental tank, is that in large tanks, when driving in hilly terrain, the fuel can accumulate so that the fuel fitting (the pipe in the tank that sucks up the fuel) cannot suck the fuel if it is relatively some fuel left in the tank.

In connection with the fuel pumps, partly the main pump and partly the transfer pump, fuel filters are often arranged downstream of the respective pump.

By fuel filter is meant here a filter which comprises a water-separating layer or membrane with a water-repellent effect, ie. a membrane where the smaller fuel molecules can pass while the water molecules are stopped.

The fuel filter also has a particle collecting layer for the purpose of stopping particles in the fuel. The water-separating layer, or membrane, is gradually degraded, i.e. the water repellent effect deteriorates, which results in more and more water molecules crossing the membrane.

In the filter, water is separated from the fuel. However, there may be certain fuel residues left in the water that are separated, which means that when water is mentioned in this context, certain fuel residues may remain.

Water is present in the fuel partly as “free water” which is easy to separate from the fuel, and partly as an emulsion in the fuel, which is more difficult to separate from the fuel as the water is then more finely divided.

In Europe and the USA, fuel contains very small amounts of water, the order of magnitude 200 ppm, ie. 200> <106 liters per liter of fuel. In countries with high humidity, the water content can be as high as 2-3%, ie. corresponding to 20000-30000 ppm.

The separated water is usually collected in a water container adjacent to the filter, and holds in the order of 0.5 - 1.5 liters. Often the container is placed under the filter and the separated water flows down into the container due to gravity. The container is then emptied manually.

The fuel is pumped with the fuel pump towards and through the fuel filter. The fuel pump has a controllable pump capacity, ie. the fuel flow may change depending on an electric fuel control signal. The fuel flow naturally varies depending on how much fuel the engine requires and is normally in the range of 1-5 liters per minute.

The invention relates partly to a method in a processing system and partly to the processing system itself.

The method will first be described and then the processing system. With reference to the flow chart in Figure 1, the method will now be described. Reference is also made to the following description of the processing system and the fuel system and in particular to Figures 2 and 3.

The invention relates to a method in a processing unit 2 for a fuel system 4 for internal combustion engine 6. The fuel system 4 comprises a fuel tank system 8 with at least one main tank 9 intended for fuel, at least one fuel pump 10, 32 arranged in connection with the main tank 9, a control unit 12 adapted to control fuel pumping from the fuel tank system 8 to the internal combustion engine 6 via a fuel line 13 by means of a control signal 14 to the fuel pump 10, 32. Furthermore, a fuel filter 16 is provided through which the pumped fuel is intended to pass, the fuel filter 16 comprises a water separating part arranged in connection with the fuel filter 16, and that the processing unit 2 comprises a memory unit 24 and an analysis unit 26.

The method comprises the steps of: - performing, with the measuring unit, measurements of one or more parameters related to the separated water; - determining measured values for said parameters; - generating a measurement signal comprising said measurement values; - receiving said measuring signal in the processing unit; - storing said measured values in the memory unit; - analyzing said stored measured values in the analysis unit using a set of predetermined rules related to the function of the fuel filter and / or the water content of the fuel; generating an indication signal in dependent said analysis, the indication signal comprising information related to the function of the fuel filter and / or the water content of the fuel.

The parameters may, for example, refer to a water level in a container intended for the separated water, or refer to a flow for the separated water. The measurements 7 can be performed continuously, or with a predetermined time interval between inter-consecutive measurements. The time interval is in the order of a number of seconds up to a number of minutes.

The measured values are preferably stored together with times when the measurements were carried out. The analysis unit is adapted to determine, by applying the predetermined rules, how the measured values change over time and to generate said information for the indication signal in dependence on this change.

The analysis unit 26 is thus adapted to analyze the stored measured values while using a set of predetermined rules related to fuel filter function and / or the water content of the fuel and to generate an indication signal 28 depending on this analysis, the indication signal 28 comprising information related to the fuel filter water function and / or fuel content. The information in the indication signal is the result of the analysis of the stored measured values carried out by the analysis unit 26 and thus contains information on the fuel filter function and / or the water content of the fuel. The information may consist of simple information which may, for example, refer to "change / do not change filter", or "good / bad fuel"; or of more complex information that shows changes in the measured values, for example together with associated time information. The information in the indication signal thus makes it possible to interpret the stored measured values with respect to the function of the fuel filter and / or the water content of the fuel. The indication signal 28 can, for example, be used so that it causes information to be presented to the driver which means that appropriate measures must be taken, e.g. changing filters, emptying the water tank 30.

The analysis unit 26 is preferably adapted to determine, using the predetermined rules, how said measured values change over time and to generate the information for the indication signal 28 in dependence on these changes. This can be determined partly by determining the rate at which the liquid level in the container changes, or by a direct flow measurement. A measure 8 of the change can be determined, for example, by forming the derivative with respect to the time of a curve representing a number of consecutive measured values. More specifically, this can be achieved by setting limit values for the rate of change (the derivative) and if the rate of change exceeds these limit values, an indication signal is generated with information representing this.

According to one embodiment, the predetermined rules comprise comparing the said measured value with a first threshold value TR1, and if the measured value is below the said first threshold value, the analysis unit is adapted to generate the information pre-indication signal indicating that the fuel filter function is not acceptable. In this case, it may be because the water separating function of the fuel filter has deteriorated and only a small part is separated by the filter.

According to another embodiment, the analysis unit comprises a second threshold value TR2, exceeding said first threshold value TR1, and if said measured value exceeds said second threshold value TR2, the analysis unit is adapted to generate information for the indication signal related to the water content of the fuel.

Furthermore, the indication signal is preferably adapted to be applied to the control unit, the amount of fuel pumped by the fuel pump being adapted to be controlled by the co-control signal depending on the information related to the function of the fuel filter and / or the water content of the fuel.

The processing unit will now be described with reference to the accompanying figures and with reference to the schematic block diagrams in Figures 2 and 3.

The invention also relates to a processing unit 2 for a fuel system 4 for a single-combustion engine 6, wherein the fuel system 4 comprises a fuel tank system 8 with at least one main tank 9 (see figure 3) intended for fuel, at least one fuel pump 10 (see figure 3), 32 arranged in connection with the main tank 9. The fuel system 4 further comprises a control unit 12 adapted to control pumping of the fuel from the fuel tank system 8 to the internal combustion engine 6 via a single fuel line 13 by means of a control signal 14 to the fuel pump 10, 32. At least one fuel filter 16 is provided. The fuel filter 16 comprises a water separating part intended to separate water from the fuel, and a measuring unit 18 arranged in connection with the fuel filter 16 and intended to perform measurements of one or more parameters related to the separated water 20. The measurements can be performed continuously, or with predetermined time intervals between consecutive. The time interval is the order of magnitude of a number of seconds up to a number of minutes.

The measuring unit 18 is further adapted to determine measured values in the dependent measurements and to generate a measuring signal 22 comprising said measured value. The measured parameter can for instance refer to a water level in a container 30 intended for the separated water 20 and the measuring unit can then be a single float, or an inductive level meter, which gives a measured value in the dependent dewatering level in the container.

According to another embodiment, the measured parameter is the water flow and the measuring unit 18 consists of a flow meter which delivers a measured value in dependence on the water flow of the separated water 20 to the container 30.

The processing unit 2 comprises a memory unit 24 and an analysis unit 26, and the processing unit 2 is adapted to receive the measurement signal 22 and to store the measured values in the memory unit 24.

In the memory unit 24, the measured values are preferably stored together with times when the measurements were performed.

In connection with the description of the method above, the calculations and analyzes which the analysis unit can carry out have been described in detail and reference is made here to that description.

Figure 5 shows a graph schematically illustrating how the measured values can be changed. The Y-axis represents a measure of the flow of the separated water in water volume per time unit, and the X-axis represents the time. In the graph, two curves 40 and 42 (first and second curves, respectively) have been drawn which represent different cases. The curves have been derived as solid lines but can also consist of measuring points where the measurements have been carried out at separate times.

The first curve 40 refers to a case where the flow gradually decreases, i.e. it can be suspected that the water-separating effect in the fuel filter gradually deteriorates and more and more water passes the filter, which of course must be avoided. In this case, the analysis is performed by comparing the measured values with a first threshold value TR1, and if the measured value is below said first threshold value, the analysis unit 26 is adapted to generate information for the indication signal 28 indicating that the function of the fuel filter 16 is not acceptable. This takes place at time t1. Of course, there is also a possibility that the fuel actually contains very little water, which further tests may show.

The second curve 42 refers to a case where the flow increases. In this case, it may be suspected that the fuel contains an excessively high water content, and the analysis unit 26 is then adapted to generate information for the indication signal 28 related to the water content of the fuel. Here, the analysis unit 26 has a second threshold value TR2, exceeding said first threshold value TR1, and if the measured value exceeds this second threshold value TR2, the analysis unit 26 is adapted to generate information for the indication signal 28 which indicates that the water content of the fuel may be unacceptably high. In the graph, this takes place at time t2. The second threshold value has been assigned a value corresponding to a level when the water content of the fuel is higher than an acceptable level.

Figure 3 shows a block diagram of a type of fuel system where the fuel tank system 8 comprises two main tanks 9. These are connected to each other so that fuel can flow from the main main tank in the figure to the left main tank. A transfer pump 32 is provided for pumping fuel from the main tank 9 to the transfer tank 31, which is considerably smaller than the main tanks. In the transfer tank 31, the fuel pump 10 is arranged. Both the transfer pump 32 and the fuel pump 10 are controlled by control signals 14 from the control unit 12. It should be noted that the transfer pump 32 may alternatively be arranged in the main tank 9, and that the fuel pump 10 may alternatively be arranged outside the transfer tank 31. There is a return line 34 between the main transfer tanks 31 and one of the main transfer tanks 9. If the transfer tank 31 becomes full, fuel can be returned via the return line 34 to the main tank 9. The fuel filter 16 is here arranged downstream of the transfer pump 32.

If it turns out that the fuel has a high water content, it may be advantageous to lower the pressure on the fuel to pass through the fuel filter, thereby increasing the filter's ability to separate the water from the fuel. To accomplish this, the indicator signal 28 is adapted to be applied to the control unit 12, the amount of pumped fuel by the fuel pump 10, 32, and in particular the transfer pump 32, being adapted to be controlled by said control signal 14 depending on the information related to the fuel filter 16 and / or fuel content. Preferably, the amount of pumped fuel included increases the content.

For example, one can deliberately fill up the transfer tank 31 to return the forced fuel to the main tank 9 via the return line 34 and thereby filter the fuel one more time.

Figure 4 shows a schematic and simplified view of a vehicle 36 comprising an internal combustion engine 6, a fuel system for the internal combustion engine, the fuel system comprising a fuel tank system 8 with a main tank intended for fuel, at least one fuel pump 10, 32 arranged adjacent to the main tank and a control unit 12 of fuel 13 from the fuel tank system to the internal combustion engine. Furthermore, a processing unit 2 is provided, which operates as described above, and which is adapted, inter alia, to receive a measurement signal 22 from the fuel filter 16 which contains 12 measurement values related to the separated water 20 and to generate an indication signal 28.

The invention further comprises a computer program in vehicles, wherein said computer program comprises program code for causing processing unit, or end computer connected to the processing unit, to perform the steps according to the method described above.

The present invention is not limited to the above-described preferred embodiments. Various alternatives, modifications, and equivalents may be employed. The above embodiments are, therefore, not to be construed as limiting the scope of the invention as defined by the appended claims.

Claims (1)

A method in a processing unit (2) for a fuel system (4) for a single-combustion engine (6), wherein the fuel system (4) comprises a fuel tank system (8) with at least one main tank (9) intended for fuel, at least one fuel pump (10, 32). ) arranged in connection with the main tank (9), a control unit (12) adapted to control pumping of the fuel from the fuel tank system (8) to the internal combustion engine (6) via a fuel line (13) by means of a control signal (14) called fuel pump (10, 32), and a fuel filter (16) through which the pumped fuel is intended to pass, the fuel filter (16) comprising a water-separating part intended to separate water from the fuel, and a measuring unit (18) arranged in connection with the fuel filter (16), and that the processing unit (2) comprises a memory unit (24) and an analysis unit (26), characterized in that the method comprises the steps of: - performing, with the measuring unit, measurements of one or more parameters related to the separated water; - determining measured values for said parameters; - generating a measurement signal comprising said measurement values; - receiving said measuring signal in the processing unit; - storing said measured values in the memory unit; - analyzing said stored measured values in the analysis unit using a set of predetermined rules related to the functional content of the fuel filter or the water content of the fuel; generating an indication signal in dependence on said analysis, the indication signal comprising information related to the function of the fuel filter 2. The method according to claim 1, wherein said measured values are stored together with times when the measurements were performed. The method of claim 1 or 2, wherein said predetermined rules comprise determining how said measured values change over time and generating said information for the indication signal in dependence on said | Marked changes 14 change. The method of any of claims 1-3, wherein said predetermining rules comprise comparing said measured value with a first threshold value TR1, and if the measured value is below said first threshold value, the generating information of the indication signal indicating that the function of the fuel filter is not acceptable. The method according to any one of claims 1-4, wherein the method comprises analyzing said low measured values in the analysis unit using a set of predetermined rules related to the water content of the fuel. 5§. The method of claim 4-4Q, wherein the method comprises generating the information for the indication signal related to fuel water content. The method according to any one of claims 4-5§_; §5_, wherein the method comprises generating the information of the indication signal related to the water content of said fuel exceeding said measured values exceeding a second threshold value TR2, exceeding a first threshold value TR1. ¥ §. The method according to any one of claims 1-61, wherein the amount of pumped fuel of the fuel pump is adapted to be controlled by means of said control signal independent of the generated indication signal l..ll.l ll. lllll..l ll. The method according to any one of claims 1-1§, wherein said parameter refers to at least one water level in a container intended for the separated water. Q fl a flow for the separated water. The method according to any one of claims 1-82, wherein said parameter relates to | 4 and I Markeraole amendments A processing unit (2) for a fuel system (4) for a single-combustion engine (6), wherein the fuel system (4) comprises a fuel tank system (8) with at least one main tank (9) intended for fuel, at least one fuel pump (10, 32) arranged in connection with the main tank (9), a control unit (12) adapted to control pumping of the fuel from the fuel tank system (8) to the internal combustion engine (6) via a fuel line (13) by means of a control signal (14) said fuel pump (10, 32), and a fuel filter (16) through which the pumped fuel is intended to pass, the fuel filter (16) comprises a water-separating part intended to separate water from the fuel, and a measuring unit (18) arranged in connection with the fuel filter (16) and intended to perform measurements of one or more parameters related to the separated water (20), to determine measured values for said one or more parameters and to generate e measuring signal (22) comprising said measured values, characterized in that the processing unit (2) comprises a single memory unit (24) and an analysis unit (26), and that the processing unit (2) is adapted to receive said measuring signal (22) and to store said measured values in the memory unit ( 24), wherein the analysis unit (26) is adapted to analyze said stored measurement values using a set of predetermined rules related to the function of the fuel filter and to generate an indication signal (28) in said analysis, wherein the indication signal (28) comprises information related to the function of the fuel filter 4412. with times when the measurements were performed. The processing unit (2) according to claim 10, wherein said measured values 4-2_1_§_. predetermined rules include determining how said measurement values change The processing unit (2) according to claim 11 or 12, wherein said over time and that the analysis unit (26) is adapted to generate said information in the indication signal (28) depending on said change. The processing unit (2) according to any one of claims 10-12, wherein I: so | Marked changes 16 said predetermined rules include comparing said measured value with a first threshold value TR1, and if the measured value is below said first threshold value, the analysis unit (26) is adapted to generate the information pre-indication signal (28) indicating that the fuel filter (16) function is not acceptable. The processing unit according to any one of claims 11-14, wherein the analysis unit (26) is adapted to analyze said stored measured values while using a set of predetermined rules related to fuel water content. 441§. The processing unit (2) according to claim 40-13 fi, wherein said analysis unit (26) is adapted to generate information for the indication signal (28) related to the water content of the fuel. the analysis unit (26) has a second threshold value TR2, exceeding said Processing Unit (2) according to any one of claims 401§4416_, the first threshold value TR1, and if said measurement values exceed said second threshold value TR2, the analysis unit (26) is adapted to the generating information. 28) related to the water content of the fuel. 4ê1§. said indicating signal (28) is adapted to be applied to said control unit (12) The processing unit (2) according to any one of claims 4911-4511, wherein the amount of pumped fuel of the fuel pump (10) is adapted to be controlled by said control signal (14) depending on the indicating signal (28). 4112. said parameter refers to at least one water level in a container (30) intended for the Processing Unit according to any one of claims 4911-46fi, wherein the separated water (20). The processing unit according to any one of claims 1911-413, wherein | Marked changes 17 said parameter refers to a flow of the separated water (20). | A computer program comprising program code for causing a processing unit, or a computer connected to the processing unit, to perform 5 steps of the method according to any one of claims 1-9fl.