NL2032341B1 - Fuel filter system for a vehicle - Google Patents

Abstract

A fuel filter system for a vehicle comprising a channel section provided with a heating arrangement, which comprises an insertion hole, a riser duct, a fuel heater, and a controller arranged for switching a power supply system of the heating arrangement between a driving mode and a standstill mode. The fuel heater comprises an elongated heating element that is covered by a sleeve, which forms a fuel passage between an intake port and the riser duct, and has an inlet opening near the intake port and an outlet opening near the riser duct, for guiding and heating the fuel to be filtered in the driving mode. A side of the sleeve facing the riser duct is provided with one or more additional cut outs, for facilitating thermally induced diffusion of fuel to be filtered towards the first fuel filter in the standstill mode.

Description

P133117NL00 — DAF0330

Title: FUEL FILTER SYSTEM FOR A VEHICLE

The invention relates to a fuel filter system for a vehicle.

Vehicles powered by an internal combustion engine typically have a fuel system with an inline fuel transfer pump that delivers fuel to the engine. A pre-filter can be installed remotely, e.g. on the chassis, between the vehicle’s fuel tank and the fuel transfer pump, to filter out the majority of water and particle contaminants from the fuel before it reaches the fuel pump. A main filter can be installed further downstream towards the engine, to give the fuel a final cleaning before 1t reaches the high pressure fuel system

Some fuels however, such as diesels and biofuels, gel at a specific low temperature, e.g. an outside temperature in winter. The paraffin usually present in the fuel starts to solidify, forming crystalized flakes.

When these flakes are present in a vehicle’s fuel system, they may clog up its filters, and reduce the flow of fuel to the injection system. As a consequence, it may be difficult to start the vehicle’s engine, or there may be variations in fuel rail pressure and the power output of the engine may be dropped.

To prevent this behaviour the fuel spec is adapted to the season, resulting In a winter and summer spec, with the winter spec having an adapted specification to prevent the solidification. However, in a large country it is difficult to guarantee the most appropriate fuel for the season is always available. Furthermore, trucks driving long distances may start in a relatively warm region while having their destination in a relatively cold region. Capable of driving these long distances on one tank, this might result into crystalized flakes problems.

By adding additives to the fuel, the temperature at which the crystalized flakes start to form can be adjusted. However, such additives may not be readily available and, moreover, may have a negative effect on the engine’s performance, fuel consumption, and life cycle.

Therefore, the standard approach to prevent a vehicle’s fuel system from clogging up, involves the application of heat. For example, it is known to equip the primary and/or secondary filter with a heating device, for heating the fuel directly before it passes though the filters. However, these types of heating devices rely on a mass flow of fuel to transfer heat from the heating device to the fuel in a controlled fashion and prevent the formation of crystalized flakes. As such, the fuel system may need to be equipped with additional heating devices for dealing with conditions in which there is no flow of fuel to the engine, such as when the vehicle is parked. This increases the complexity and manufacturability of the vehicle's fuel system, thereby decreasing the reliability of the system.

It is an object of the present invention to provide a fuel filter system that minimalizes filter clogging, in conditions with or without a mass flow of fuel to the engine, with improved reliability.

SUMMARY

In summary, the invention pertains to a fuel filter system for a vehicle, comprising a housing and a heating arrangement. The housing comprises a channel section for guiding fuel to be filtered through a first fuel filter and a second fuel filter. The channel section has an intake port for receiving the fuel to be filtered upstream the first fuel filter, and a first connector for connecting to a low pressure side of a fuel pump downstream the first fuel filter. The channel section has a second connector for connecting to a high pressure side of the fuel pump upstream the second fuel filter, and an output port for dispensing filtered fuel to an engine of the vehicle downstream the second fuel filter.

The heating arrangement is provided in the channel section of the housing for heating fuel to be filtered by the fuel filter system, and comprises an insertion hole, a riser duct, a fuel heater, and a controller.

The insertion hole extends from an outer surface of the channel section to the intake port. The riser duct extends laterally outward from the insertion hole, for guiding the fuel to be filtered from the intake port towards the first fuel filter. The fuel heater is mounted to the outer surface and extends into the insertion hole, and is arranged for heating the fuel to be filtered. The controller is arranged for switching a power supply system of the heating arrangement between a driving mode, in which fuel in the fuel filter system has a mass flow, and a standstill mode, in which the fuel in the fuel filter system is stagnant.

The fuel heater comprises an elongated heating element that is covered by a sleeve, which forms a fuel passage that runs adjacently along the heating element and extends between the intake port and the riser duct.

The fuel passage has an inlet opening near the intake port and an outlet opening near the riser duct, for guiding and heating the fuel to be filtered in the driving mode. A side of the sleeve facing the riser duct is provided with one or more additional cut outs, such as holes or slots e.g. arranged in an array or matrix along or across the elongated heating element.

While having one or more additional cut outs in the sleeve may reduce the fuel guiding properties of the fuel passage from the inlet opening towards the outlet opening, thereby decreasing transfer of heat from the heating element to the fuel in the driving mode, it facilitates thermally induced diffusion of fuel towards the first fuel filter in the standstill mode.

Accordingly, the heating arrangement provides a single fuel heater that minimalizes formation of crystalized flakes that can clog the filters of the fuel filter system, both in flow conditions of the fuel, as well as in no- flow conditions of the fuel.

In some embodiments, the power supply system can comprise a low voltage power terminal, a high voltage power terminal, and a power converter. The low voltage power terminal may be electrically connected to the fuel heater, and may be connectable to a first power source for receiving alow voltage power input. The high voltage power terminal may be connectable to a second power source for receiving a high voltage power input. The power converter may have an input terminal coupled to the high voltage power terminal and an output terminal coupled to the low voltage power terminal. Accordingly, the heating arrangement can be supplied with power from the first power source, such as a battery unit of the vehicle, or from the second power source, such as an external power outlet, e.g. by a power cable.

The controller can be arranged for controlling the power supply system, in the standstill mode, to convert the high voltage power input to an output equal to the low voltage power input. In this way, the fuel heater receives the same input power regardless of whether the first power source or the second power source is operatively connected to the fuel heater.

To electrically connect and disconnect the fuel heater to the power supply, the fuel heater can comprise a bimetal switch, wherein the bimetal switch is thermally coupled to the elongated heating element. Accordingly, when the fuel temperature drops below a first predefined threshold, the bimetal switch can electrically connect the fuel heater to the power supply, to heat up the fuel. Conversely, when the fuel temperature exceeds a second predefined threshold, the bimetal switch can electrically disconnect the fuel heater from the power supply, to avoid excessive heating of the fuel. The first threshold can have the same value as the second threshold, or the first and second threshold can have different nominal values to account for measurement errors, e.g. inherent to the temperature sensing properties of the bimetal switch.

The fuel heater may comprise a flange, provided at a distal end of the elongated heating element near the intake port, and extending radially outward from the sleeve towards an inner wall of the insertion hole, wherein the flange provides a seal against the inner wall around the circumference 5 of the sleeve. As a result, fuel to be filtered cannot pass around the circumference of the sleeve but instead is guided into the sleeve, and along the elongated heating element, so that, in the driving mode, formation of crystal flakes is minimalized by maximizing the flow of fuel to be filtered along the heating element. As such, formation of crystal flakes is further mimimalized, in particular in the driving mode.

The fuel heater may comprise a sealing element, such as an O-ring or a gasket, provided at a proximal end of the elongated heating element near the outer surface of the channel section, to seal the insertion hole. In this way a leak-proof connection between the channel section and the fuel heater can be provided, to prevent fuel leakage. By having the sealing element provided near the outer surface of the channel section, the effective heating area of the elongated heating element, extending between the intake port and the riser duct, for heating the fuel to be heated, is maximized.

In some embodiments, the elongated heating element can be provided with one or more protrusions on an ohmic heating part, that extend into the fuel passage. In this way, the effective heating area of the elongated heating element can be further increased, while the protrusions can also be arranged for directing the fuel flow to be filtered through the fuel passage.

The sleeve may further comprise one or more supplementary cut outs provided on a side of the sleeve facing away from the riser duct. This further facilitates thermally induced diffusion of fuel to be filtered towards the first fuel filter in the standstill mode, while the fuel passage extending between the intake port and the riser duct can remain mostly intact, for guiding a mass flow of fuel to be filtered along the elongated heating element in the driving mode.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further elucidated in the figures:

FIG 1 illustrates an embodiment of a fuel filter system;

FIG 2 illustrates an embodiment of a heating arrangement of the fuel filter system described herein;

FIG 3 illustrates another or further embodiment of the fuel filter system described herein;

FIGs 4A and 4B illustrate a top view and bottom view, respectively, of an embodiment of a fuel heater of the fuel filter system described herein.

DETAILED DESCRIPTION

The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown.

In the drawings, the absolute and relative sizes of systems, components, layers, and regions may be exaggerated for clarity. Embodiments may be described with reference to schematic and/or cross-section illustrations of possibly idealized embodiments and intermediate structures of the invention. In the description and drawings, like numbers refer to like elements throughout. Relative terms as well as derivatives thereof should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the system be constructed or operated in a particular orientation unless stated otherwise.

FIG 1 illustrates a fuel filter system 100 for a vehicle, such as a truck. Alternatively, the vehicle can be any land, air, or naval type vehicle that is powered by an internal combustion engine, such as a diesel engine or a biofuel engine. The fuel filter system 100 comprises a housing 110 provided with a first fuel filter 50, e.g. a primary, or pre-filter, and a second fuel filter 60, e.g. a secondary, or main filter. The housing further comprises a channel section 120 for guiding fuel to be filtered through a first fuel filter 50 and a second fuel filter 60. For this reason, the channel section 120 comprises an intake port 121 upstream the first fuel filter 50, a first connector 122 downstream the first fuel filter 50, a second connector 123 upstream the second fuel filter 60, and an output port 124 downstream the second fuel filter 60. The intake port 121 is e.g. connectable to a fuel tank of the vehicle, for receiving fuel to be filtered. The output port 124 is e.g. connectable to a high pressure fuel system, for dispensing filtered fuel to the engine of the vehicle. A fuel pump (not shown), such as an inline fuel transfer pump, can be coupled to the housing 110, so that the low pressure side of the fuel pump is connected to the first connector 122 and the high pressure side of the fuel pump is connected to the second connector 123. In this way, a mass flow of fuel can be created through the fuel filter system, from the intake port 121 towards the output port 124.

The channel section 120 is provided with a heating arrangement 130, for heating fuel to be filtered by the fuel filter system. The heating arrangement 130 comprises an insertion hole 131 that extends from an outer surface 125 of the channel section 120 to the intake port 121. The insertion hole 131 provides a cavity inside the channel section 120 for housing a fuel heater 132, which is mounted to the outer surface 125 and extends into the insertion hole 131, and which is arranged for heating the fuel to be filtered. A riser duct 133 extends laterally outward from the insertion hole 131 towards the first fuel filter 50. Accordingly, fuel to be filtered is guided from the intake port 121, along the fuel heater 132 located in the insertion hole 131, and towards the first fuel filter 50.

The heating arrangement 130 is further provided with a controller 134, arranged for switching a power supply system 200 of the heating arrangement 130 between a driving mode and a standstill mode. In the driving mode, fuel in the fuel filter system 100 has a mass flow. The driving mode may be applicable in conditions when the engine of the vehicle is running and thus a certain fuel demand from the engine is to be provided by the fuel pump. In the standstill mode, fuel in the fuel filter system 100 is stagnant. The standstill mode may be applicable in conditions when the engine of the vehicle is switched off, in particular in relatively cold outside temperatures and for periods of time that are long enough for the fuel filter system to cool off towards a temperature at which crystalized flakes begin to form in the fuel, e.g. when the vehicle is parked for an overnight stop.

As can be seen in FIG 2, the fuel heater 132 comprises an elongated heating element 135 that is covered by a sleeve 136. The heating element 135 is preferably made of a material suitable for ohmic heating that has a relatively high thermal conductivity, e.g. a metal such as an aluminium, steel, or copper alloy. The sleeve is preferably made of an electrically insulating material, such as a polymer, ceramic, or composite.

The sleeve 136 forms a fuel passage that runs adjacently along the heating element 135 and extends between the intake port 121 and the riser duct 133. The fuel passage has an inlet opening 137 near the intake port 121, e.g. at a distal end of the heating element 135, and an outlet opening 138 near the riser duct 133, e.g. at a proximal end of the heating element 135. Accordingly, in the driving mode, fuel to be filtered is guided through the fuel passage and heated along the heating element 135.

A side of the sleeve 136 facing the riser duct 133 is provided with one or more additional cut outs 139. The additional cut outs 139 can e.g. be holes arranged in rows and/or columns along the side of the sleeve 136 facing the riser duct 133. Alternatively, the additional cut outs 139 can be in the form of slots, e.g. having a long side extending along the long side of the elongated heating element 135, or having a long side oriented perpendicularly, or diagonally, to the long side of the heating element 135.

As such, the one or more additional cut outs 139 provide additional openings on the side of the sleeve 136 facing the riser duct 133, to facilitate thermally induced diffusion of fuel to be filtered towards the first fuel filter in the standstill mode.

As illustrated in FIG 2, the fuel heater 132 comprises a flange 140, provided at a distal end of the elongated heating element 135 near the intake port 121. The flange 140 can e.g. be provided around or near the inlet opening 137 of the fuel passage. The flange 140 extends radially outward from the sleeve 136 towards an inner wall 141 of the insertion hole 131. The flange 140 provides a seal against the inner wall 141 around the circumference of the sleeve 136. Accordingly, fuel is guided from the intake port 121 into the inlet opening 137 of the fuel passage, while fuel is prevented from flowing around the sleeve 136, in the driving mode.

To seal the insertion hole 131, the fuel heater 132 comprises a sealing element 142, such as an O-ring or a gasket. The sealing element 142 can e.g. be mounted between the fuel heater 132 and the inner wall 141 of the insertion hole 131, as illustrated in FIG 2, at the proximal end of the elongated heating element near the outer surface of the channel section. For example, the sealing element 142 can be mounted between the fuel heater 132 and the inner wall 141 of the insertion hole 131 near the outlet opening 138 of the fuel passage. By having the sealing element 142 mounted near the outlet opening 138 of the fuel passage and the entry port of the riser duct 133, fuel is optimally directed from the heating element 135 towards the riser duct 133, in both the driving mode as well as in the standstill mode, to limit the formation of crystalized flakes.

As illustrated in FIG 2, the elongated heating element 135 can also be provided with one or more protrusions 143 that extend into the fuel passage, to maximize the area of the heating element 135. As such the heat transfer rate from the heating element 135 to the fuel is improved both in the standstill mode, in no-flow conditions, as well as in the driving mode, when there 1s a flow of fuel through the fuel filter system 100. The heating element 135 can for example comprise one or more profiled sheets, having bent segments that form the protrusions 143. Besides providing an increased surface area for heat transfer from the heating element 135 to the fuel to be filtered, the protrusions 143 can be oriented in the fuel passage at specific angles relative to the long side of the heating element 135, e.g. to create turbulence in the mass flow of fuel to increase the heat transfer rate from the heating element 135 to the fuel. For example, in the driving mode, the protrusions 143 can direct the flow of fuel along a pattern across the heating element 135, such as a zig-zag pattern.

To control the temperature of the fuel in the fuel filter system 100, the fuel heater 132 can be activated and deactivated by having a bimetal switch 144 arranged for electrically connecting and disconnecting, respectively, the fuel heater 132 to the power supply system, for example to couple to a battery unit of the vehicle or to an external power source, e.g. provided at an overnight parking area for vehicles. The bimetal switch 144 is thermally coupled to the elongated heating element 135, such that the switch responds to a change in fuel temperature. The bimetal switch 144 can for example be arranged for activating the fuel heater 132 when the fuel temperature is between —5 and +10 degrees Celsius, preferably between —1 and +7 degrees Celsius. Conversely, the bimetal switch 144 can e.g. be arranged for deactivating the fuel heater 132 when the fuel temperature is between +5 and +20 degrees Celsius, preferably between +5 and +15 degrees

Celsius. The temperature ranges mentioned above account for control variability, e.g. caused by measurement errors of the bimetal switch, to ensure that the actual fuel temperature does not drop below a certain threshold at which crystalized flakes begin to form, and that the actual fuel temperature does not exceed a certain threshold, e.g. to limit energy consumption of the fuel heater 132.

FIG 3 illustrates another or further embodiment of the fuel filter system 100, comprising a power supply system 200 operatively connected to the heating arrangement 130. The power supply system 200 comprises a low voltage power terminal 201, such as a 12V DC connector. The low voltage power terminal 201 is electrically connected to the fuel heater 132, and is connectable to a first power source 210, such as a battery unit of the vehicle, to receive a low voltage power input, e.g. a DC power input with a voltage between 8-16V. The fuel heater 132 may be continuously operable on the low voltage power input provided by the first power source 210. Accordingly, in the driving mode, e.g. when the engine is running or temporarily switched off, e.g. with the ignition switched on, the battery unit of the vehicle may independently power the fuel heater 132 for heating the fuel in the fuel filter system 100.

The power supply system 200 may further comprise a power converter 202 and a high voltage power terminal 203. The power converter 202 has an input terminal coupled to the high voltage power terminal 203 and an output terminal coupled to the low voltage power terminal 201. The high voltage power terminal 203 is connectable to a second power source, such as an external power outlet, for receiving a high voltage power input, e.g. an AC power input with a voltage between 100-150V, or between 200- 260V. The high voltage power terminal 203 can e.g. be coupled to a connector 204 of a power cable 205, which is plugged into a power outlet 206 of an external power source. The external power source can for example be provided at an overnight parking area for vehicles.

In the standstill mode, the controller 134 can be arranged for controlling the power supply system 200, e.g. by controlling the power converter 202, to convert the high voltage power input to an output equal to the low voltage power input. In this way, when the vehicle is e.g. parked at an overnight parking area, the heating assembly 130 of the fuel filter system 100 can be connected to a power outlet 206 of an external power source, e.g. to receive a 110V AC power input, which is converted to a 12V

DC power output that feeds the fuel heater 132. As such, the fuel heater 132 can be supplied with its normal continuous operating voltage to heat the fuel in the fuel filter system and prevent the formation of crystalized flakes therein, without depleting the vehicle’s battery unit during conditions in which the engine is switched off for extended periods of time.

FIGs 4A and 4B illustrate a top view and bottom view, respectively, of another or further embodiment of a fuel heater 132 of the fuel filter system described herein. The sleeve 136 has an array of additional cut outs 139 provided on a side of the sleeve that, when mounted in the heating arrangement, faces the riser duct. The sleeve 136 also comprises a number of supplementary cut outs 145 provided on a side opposite the side facing the riser duct, thus facing away from the riser duct. The supplementary cut outs 145 increase the outlet area through which fuel can escape from the fuel passage in the standstill mode, when the activated heating element induces diffusion of the fuel, without significantly limiting the ability of the sleeve 136 to guide a mass flow of fuel from the inlet opening 137 towards the outlet opening 138 in the driving mode.

It is thus believed that the operation and construction of the present invention will be apparent from the foregoing description and drawings appended thereto. For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

The invention applies not only to automotive applications where the fuel filter system is used for automotive purposes, but also to other technical, industrial or agricultural applications where a fuel filter system is used. It will be clear to the skilled person that the invention is not limited to any embodiment herein described and that modifications are possible which may be considered within the scope of the appended claims. Also kinematic inversions are considered inherently disclosed and can be within the scope of the invention. In the claims, any reference signs shall not be construed as limiting the claim.

The terms 'comprising’ and ‘including’ when used in this description or the appended claims should not be construed in an exclusive or exhaustive sense but rather in an inclusive sense. Thus expression as including’ or ‘comprising’ as used herein does not exclude the presence of other elements, additional structure or additional acts or steps in addition to those listed. Furthermore, the words ‘a’ and ‘an’ shall not be construed as limited to ‘only one’, but instead are used to mean ‘at least one’, and do not exclude a plurality. Features that are not specifically or explicitly described or claimed may additionally be included in the structure of the invention without departing from its scope.

Expressions such as: "means for ...” should be read as: "component configured for …" or "member constructed to ..." and should be construed to include equivalents for the structures disclosed. The use of expressions like: "critical", "preferred", "especially preferred" etc. is not intended to limit the invention. To the extent that structure, material, or acts are considered to be essential they are inexpressively indicated as such. Additions, deletions, and modifications within the purview of the skilled person may generally be made without departing from the scope of the invention, as determined by the claims.

Claims (8)

CONCLUSIONS 1. A fuel filter system for a vehicle, comprising: filtering fuel, and a first connector for coupling to a low pressure side of a fuel pump downstream of the first fuel filter, the channel portion including a second connector for coupling to a high pressure side of the fuel pump upstream of the second fuel filter, and an exhaust port for providing of filtered fuel to an engine of the vehicle downstream of the second fuel filter; - a heating device provided in the channel portion of the housing for heating fuel to be filtered by the fuel filter system, comprising: o an insertion hole extending from an outer surface of the channel portion towards the inlet port; o a riser tube, extending laterally from the insertion hole, for guiding the fuel to be filtered from the inlet port towards the first fuel filter; o a fuel heater, mounted on the outer surface and extending into the insertion hole, and adapted to heat the fuel to be filtered; and o a controller adapted to switch a power supply system of the fuel heater between a driving mode, in which fuel in the fuel filter system has a mass flow, and a standstill mode, in which the fuel in the fuel filter system is stationary; wherein the fuel heater includes an elongated heating element covered by a sleeve, the sleeve defining a fuel passageway adjacent the heating element and extending between the inlet port and the riser, the fuel passageway having an inlet opening proximate the inlet port and an outlet opening proximate the dip tube, for guiding and heating the fuel to be filtered in driving mode; wherein a side of the sleeve facing the riser is provided with one or more additional cutouts to facilitate thermally induced diffusion of fuel to be filtered towards the first fuel filter in standstill mode. 2. Fuel filter system according to claim 1, wherein the power system comprises: - a low-voltage power connection, electrically connected to the fuel heater, and connectable to a first power source for receiving a low-voltage power input; — a high-voltage power connection, which can be connected to a second power source for receiving a high-voltage power input; and — a power converter, with an input terminal connected to the high-voltage power terminal and an output terminal connected to the low-voltage power terminal. A fuel filter system according to claim 2, wherein, in the standstill mode, the controller is arranged to control the power system to convert the high voltage power input to an output equal to the low voltage power input. 4. Fuel filter system according to claim 3, wherein the fuel heater comprises a bimetallic switch adapted to electrically connect and disconnect the fuel heater from the power system, wherein the bimetallic switch is thermally coupled to the elongated heating element. 5. Fuel filter system according to any one of the preceding claims, wherein the fuel heater comprises a flange provided at a distal end of the elongated heating element proximate the inlet port and extending radially outwardly from the sleeve towards an inner wall of the insertion hole, wherein the flange provides a seal against the inner wall along the periphery of the sleeve, for guiding fuel to be filtered into the sleeve. 6. Fuel filter system according to any one of the preceding claims, wherein the fuel heater comprises a sealing element, which is provided at a proximal end of the elongated heating element near the outer surface of the channel portion, for sealing the insertion hole. 7. Fuel filter system according to any of the preceding claims, wherein the elongated heating element is provided with one or more protrusions that extend into the fuel passage. 8. Fuel filter system according to any of the preceding claims, wherein the sleeve comprises one or more additional cutouts provided on a side of the sleeve facing away from the riser.