SE1550935A1 - Fuel system for an internal combustion engine - Google Patents

Fuel system for an internal combustion engine Download PDF

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Publication number
SE1550935A1
SE1550935A1 SE1550935A SE1550935A SE1550935A1 SE 1550935 A1 SE1550935 A1 SE 1550935A1 SE 1550935 A SE1550935 A SE 1550935A SE 1550935 A SE1550935 A SE 1550935A SE 1550935 A1 SE1550935 A1 SE 1550935A1
Authority
SE
Sweden
Prior art keywords
fuel
pipe
filter
bypass
bypass valve
Prior art date
Application number
SE1550935A
Other languages
Swedish (sv)
Other versions
SE539340C2 (en
Inventor
Kylström Kim
Original Assignee
Scania Cv Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Scania Cv Ab filed Critical Scania Cv Ab
Priority to SE1550935A priority Critical patent/SE539340C2/en
Priority to DE112016002669.2T priority patent/DE112016002669T5/en
Priority to PCT/SE2016/050649 priority patent/WO2017003359A1/en
Publication of SE1550935A1 publication Critical patent/SE1550935A1/en
Publication of SE539340C2 publication Critical patent/SE539340C2/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/0047—Layout or arrangement of systems for feeding fuel
    • F02M37/0052—Details on the fuel return circuit; Arrangement of pressure regulators
    • F02M37/0058—Returnless fuel systems, i.e. the fuel return lines are not entering the fuel tank
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
    • B01D35/14—Safety devices specially adapted for filtration; Devices for indicating clogging
    • B01D35/143—Filter condition indicators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/0011—Constructional details; Manufacturing or assembly of elements of fuel systems; Materials therefor
    • F02M37/0023—Valves in the fuel supply and return system
    • F02M37/0029—Pressure regulator in the low pressure fuel system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/22—Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines, e.g. arrangements in the feeding system
    • F02M37/32—Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines, e.g. arrangements in the feeding system characterised by filters or filter arrangements
    • F02M37/36—Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines, e.g. arrangements in the feeding system characterised by filters or filter arrangements with bypass means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/22—Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines, e.g. arrangements in the feeding system
    • F02M37/32—Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines, e.g. arrangements in the feeding system characterised by filters or filter arrangements
    • F02M37/46—Filters structurally associated with pressure regulators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
    • B01D35/14—Safety devices specially adapted for filtration; Devices for indicating clogging
    • B01D35/147—Bypass or safety valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/22—Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines, e.g. arrangements in the feeding system
    • F02M37/32—Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines, e.g. arrangements in the feeding system characterised by filters or filter arrangements

Abstract

Abstract The invention relates to a fuel system for an internal combustion engine (2), comprising a firstfuel tank (14), a first fuel pump (16), a first fuel filter (18) and a second fuel filter (20). A firstfuel pipe (22) is arranged in fluid connection with the first fuel tank (14) and the first fuel filter(18), a second fuel pipe (24) is arranged in fluid connection with the first fuel filter (18) and thefirst fuel pump (16), a third fuel pipe (26) is arranged in fluid connection with the first fuelpump (16) and the second fuel filter (20), and a fourth fuel pipe (28) is arranged in fluidconnection with the second fuel filter (20) and a high-pressure circuit of the fuel system (10). Abypass valve (30) is arranged to allow fuel to bypass the first fuel filter (18) via a bypass pipe(32) arranged in fluid connection with the first fuel pipe (22) and the second fuel pipe (24),wherein the bypass valve (30) is adapted to be controlled based on the supply pressure downstream ofthe first fuel pump (16). (Fig. 2)

Description

1 Fuel system for an internal combustion engine TECHNICAL FIELD The present invention relates to a fuel system for a combustion engine, an internalcombustion engine system comprising the fuel system and a vehicle comprising the fuel system.BACKGROUND AND PRIOR ART An internal combustion engine such as a diesel engine or an Otto engine is equipped with afuel system to transport fuel frorn one or several fuel tanlts to the internal cornhustionengines injection systern. The fuel systern cornprises one or several fuel purnps which rnay hernechanically rlriven hy the internal combustion erlgine or may be electrically driven hy anelectric machine. The fuel systern typically cornprises a low pressure circuit with first lowpressure fuel purnp and a high pressure circuit with a high pressure fuel pump. "lhe fuel rsurnpscreate a fuel flow and a pressure to transport the firel to the internal cornhustion enginesirrlection systern, vvhich supplies the firel to the cornhilstiorl charnloer' of the internal cornbtrstion engine. "lhe fuel systern also comprises one or several fuel filters, through which the fuel passes and isfilterecl on its way towards the internal rtonrhilstiorl errgine. Particles in the fuel will get stircltin the filel filter during filtratiorr and the firel filter tvill grarlually hecorne cloggerl. When a fuelfilter is cloggecl or' partly cloggetl hy particles, the transport of fuel front the fuel tanlts to theinternal combustion eriginefis. injection systern is hinderecl or rnacle more difficult since it isdifficult for the fuel to pass through the fuel filter. Different fuels are more or less prone toclog the fuel filters. When biodiesel fuels are used, such as FAlJlE-fuels (fatty-acid rnethylester), the fuel filters tend to become clogged more rapidly than when an ordinary diesel fuelis used. Also, suctiorr filters are likely to hecorrle clogged more rapiclly' than pressure filters.This is particularly a prohlern during cold start where a fuel purnp rlriven hy the starter rnotor is rrsecl to feed fuel through the suction filter. ln such cases, the fuel purnp rnay not he able to 2force enough fuel through the suction filter and thus transfer enough fuel to start the coinbustioit engine. Such disruptions of the coinbustion engine are disadvantageous.
Document JP2iï=Ü727êš2í>1 A describes a bypass path for a pressure fiiter pressurized between afeed pump and an injection purnp in a lovv pressure circuit of a fuei system, However, saiddocument does not deai vtfith probients relating to suction fiiters, vvhich are sensitive andmore likely to be clogged than pressure filters. Despite known solutions in the field, there isstill a need to develop a fuel system for a combustion engine which reduces the risk of operational disruptions ofthe internal combustion engine.SUMMARY OF THE INVENTION lt is an object of the present invention to provide a fuel system for an internal combustion engine which reduces the risk of operational disruptions in the combustion engine.
Another object of the present invention is to provide a fuel system for an internal combustion engine which is suitable for biodiesel fuels.
The objects are attained by a fuel system as defined in the appended claims which relate to afuel system for an internal combustion engine comprising a low-pressure circuit with a firstfuel tank, a first fuel pump, a first fuel filter arranged upstream of the first fuel pump and asecond fuel filter arranged downstream of the first fuel pump. A first fuel pipe is arranged influid connection with the first fuel tank and the first fuel filter and a second fuel pipe isarranged in fluid connection with the first fuel filter and the first fuel pump. Further, a thirdfuel pipe is arranged in fluid connection with the first fuel pump and the second fuel filter, anda fourth fuel pipe is arranged in fluid connection with the second fuel filter and a high-pressure circuit of the fuel system. A bypass valve is arranged to allow fuel to bypass the firstfuel filter via a bypass pipe arranged in fluid connection with the first fuel pipe and the secondfuel pipe. The bypass valve is adapted to be controlled based on the supply pressure downstream ofthe first fuel pump.
By arranging a bypass valve such that fuel is allowed to bypass the first fuel filter based on thesupply pressure downstream of the first fuel pump in the low-pressure circuit, it can beensured that fuel with sufficient supply pressure is provided to the high-pressure circuit. ln this way it can be assured that the internal combustion engine can receive sufficient amount 3of fuel even when the first fuel filter is clogged. The risk for operational disruptions of theinternal combustion engine is thereby reduced, especially in connection with the use of biodiesel fuels.
The herein mentioned objects are also attained by an internal combustion engine system anda vehicle comprising the fuel system as generally defined above and as defined in the appended claims.
Further features, advantages and objects will be described below with reference to the detailed description and the appended drawings.BRIEF DESCRIPTION OF THE DRAWINGS For the understanding of the present invention and further objects and advantages of it, thedetailed description set out below can be read together with the accompanying drawings, in which the same reference notations denote similar items in the various diagrams, and in which:Fig. 1 schematically illustrates a vehicle according to an embodiment of the invention;Fig. 2 schematically illustrates a fuel system for an internal combustion engineaccording to an embodiment of the invention;Fig. 3a schematically illustrates a bypass valve of a fuel system according to anembodiment of the invention; andFig. 3b schematically illustrates a bypass valve of a fuel system according to an embodiment of the invention.
DETAILED DESCRPTION OF THE INVENTION As generally described above, the fuel system comprises a low-pressure circuit with a first fueltank, a first fuel pump, a first fuel filter arranged upstream ofthe first fuel pump and a secondfuel filter arranged downstream ofthe first fuel pump. A first fuel pipe is arranged in fluidconnection with the first fuel tank and the first fuel filter and a second fuel pipe is arranged influid connection with the first fuel filter and the first fuel pump. Further, a third fuel pipe is arranged in fluid connection with the first fuel pump and the second fuel filter, and a fourth 4 fuel pipe is arranged in fluid connection with the second fuel filter and a high-pressure circuitof the fuel system. The bypass pipe in the fuel system is arranged in fluid connection with thefirst fuel pipe and the second fuel pipe and the bypass valve is arranged in fluid connectionwith the bypass pipe. Preferably, the bypass valve is directly connected to the bypass pipe.Further, the bypass valve is suitably arranged such that when the bypass valve is in an openposition, fuel flows from the fuel tank through the first fuel pipe, the bypass pipe and thebypass valve to the second fuel pipe and further to the first fuel pump. When the bypass valveis in a closed position, fuel flows from the fuel tank through the first fuel pipe and the first fuelfilter to the second fuel pipe and the first fuel pump. The bypass valve is thus arranged to fluidly connect or disconnect the first fuel pipe with the second fuel pipe via the bypass pipe.
The fuel system may comprise further components not mentioned herein according tocommon fuel systems. The low-pressure circuit may for example comprise more than one fueltank and/or more than one fuel pump. With the first fuel pump in this connection is thusmeant a fuel pump arranged to suck fuel through the first fuel filter, i.e. a suction filter asfurther described below. The fuel system may comprise a second fuel pump downstream ofthe first fuel pump. The high-pressure circuit typically comprises a high pressure pump and an injection system for the internal combustion engine.
Since the first fuel filter is arranged upstream ofthe first fuel pump the first fuel filter is asuction filter. The fuel pump is preferably a low pressure fuel pump. Suction filters are morelikely to be clogged than pressure filters, since the first fuel pipe is not pressurized and thepressure of the fuel in the first pipe corresponds to the atmospheric pressure. Thus, thepressure drop through the suction filter corresponds to the atmospheric pressure. When thefirst fuel filter is clogged or partly clogged, the first fuel pump can have difficulties to suck fuelthrough the first fuel filter. Therefore, the first fuel pump may not be able to provide sufficientsupply pressure downstream of the first fuel pump and further to the high-pressure circuit. Bysupply pressure is thus meant fuel pressure downstream of the first fuel pump. Therefore, the internal combustion engine will not receive sufficient amount of fuel.
Depending on the fuel type, the temperature of the fuel may also cause problems whensucking the fuel through the first fuel filter. The viscosity of biodiesel fuels, such as FAM E- fuels, increases at relatively low temperatures (much more than petroleum diesel). The 5resistance in the first fuel pipe between the fuel tank and the first fuel filter will thus increaseat low temperatures, which will affect the ability of the fuel pump to provide sufficient supply pressure which is needed to supply sufficiently fuel to the internal combustion engine.
By controlling the bypass valve based on the supply pressure downstream of the first fuelpump it can be ensured that the risk for operational disruptions of the internal combustionengine is reduced in a reliable and efficient way. Thus, when the first fuel filter is clogged orthe first fuel pump is for any other reason hindered from providing sufficient supply pressuredownstream ofthe first fuel pump, the bypass valve is adapted to be controlled or moved toan open position, such that fuel may bypass the first fuel filter. ln this way, the fuel pump isable to provide fuel with sufficient supply pressure to the high-pressure circuit of the fuel system.
As soon as the supply pressure downstream of the fuel pump is high enough for the high-pressure circuit to function properly, the bypass valve is adapted to be controlled or moved toa closed position, such that fuel will be fed through the first fuel filter. ln this way, it can be ensured that unfiltered fuel is not supplied to the fuel pump longer than necessary.
According to an aspect ofthe invention the bypass valve is adapted to be controlled based onthe supply pressure downstream of the second fuel filter in the fourth fuel pipe. The secondfuel filter is also located downstream of the first fuel pump, whereby the definition of supplypressure applies, i.e. that the supply pressure is fuel pressure downstream of the first fuelpump. By using the supply pressure downstream of the second fuel filter it is the actual supplypressure which is provided to the high-pressure circuit that is controlling the bypass valve. lnthis way, it can be ensured that sufficient supply pressure can be provided for the high-pressure circuit so that the internal combustion engine can function properly. Alternatively,the bypass valve is controlled based on the supply pressure in the third fuel pipe, downstreamof the fuel pump and upstream ofthe second fuel filter. The expected pressure drop over thesecond fuel filter is then considered to determine if the current supply pressure is sufficient for the high-pressure circuit.
According to an aspect ofthe invention the bypass valve is adapted to be controlled to aclosed position, such that the fuel flows through the first fuel filter, when the supply pressure exceeds a predetermined value. The predetermined value corresponds suitably to a minimum 6supply pressure which enables proper function of the high-pressure circuit and supply of sufficient amount of fuel to the internal combustion engine.
According to a further aspect of the invention the bypass valve is adapted to be controlled toan open position, such that the fuel flows through the bypass pipe, when the supply pressureis below a predetermined value. The predetermined value is suitably a supply pressure whichcorresponds to a value in which proper function of the high-pressure circuit and supply ofsufficient amount of fuel to the internal combustion engine are prevented. The value issuitable below the predetermined value corresponding to a minimum supply pressure which enables proper function of the high-pressure circuit.
According to another aspect of the invention the bypass valve is a hydraulic valve. Differentconstructions ofthe hydraulic valve are possible, but when the bypass valve is a hydraulic valve, it is affected by the supply pressure downstream of the first fuel pump. The bypass valve is suitably self-adjusting and passive control of the bypass valve can thereby be achieved. ln this way, no additional electronic control devices, pressure sensing devices and similar areneeded to control the bypass valve and thus the bypass of the first fuel filter. A hydraulicbypass valve is robust and durable and thereby minimizes the risk for operational disruptions due to, for example, wear of the bypass valve.
According to a further aspect of the invention the bypass valve is a spring loaded valveconnected to the bypass pipe and a fuel pipe downstream ofthe first fuel pump, wherein abody with a passage is arranged such that a spring device can act with a spring force on a firstside ofthe body and a force associated with the supply pressure can act on a second side of the body. The first side of the body is opposite to the second side of the body.
The bypass valve is suitably connected to the fourth fuel pipe downstream of the first fuelpump. The bypass valve is preferably connected to the fuel pipe downstream of the first fuelpump via a control conduit arranged in fluid connection with the fuel pipe. The supplypressure in the control conduit is thus essentially the same as in the fuel pipe downstream ofthe first fuel pump. The pressure in the control conduit is suitably always higher than atmosphere. 7 According to one embodiment ofthe invention, the spring loaded valve suitably compriseshousing with an opening to the control conduit. The spring device and the body are arrangedinside the housing. The spring device is arranged on a first side of the body inside the housingand the opening to the control conduit is on a second side of the body. The second side isopposite the first side. The spring force and the force associated with the supply pressure arethus acting on the body in opposing directions. The force acting on the second side ofthebody depends on the supply pressure and the area ofthe body on which the supply pressureacts. The force acting on the second side ofthe body thus depends on the area of the body, which is facing in the direction of the control conduit.
The body is suitably arranged inside the housing such that the first side of the body and thehousing defines a cavity in which the spring device is arranged. The longitudinal extension ofthe body is preferably perpendicular to the extension of the passage through the body. Thebody suitably extends longitudinally between the first side and the second side. The body issuitably arranged to be moved in the longitudinal direction by means ofthe spring forceand/or the force associated with the supply pressure. The body can thus act as a piston insidethe housing. When the force associated with the supply pressure moves the body, the springdevice is compressed. The cavity is thus decreased and the air inside the cavity may be ventedthrough a venting arrangement arranged in fluid connection with the cavity. When the springforce moves the body, the spring device extracts and the cavity is expanded. The venting arrangement is suitably a venting conduit arranged in fluid connection with the cavity and the bypass pipe.
Suitable, the bypass valve is adapted to be in a closed position when the spring force is smallerthan the force associated with the supply pressure, wherein the body is positioned such thatthe passage is not in fluid communication with the bypass pipe. When the provided supplypressure results in a force acting on the body which is larger than the spring force, the fluidthus flows from the fuel tank through the first fuel pipe, the first fuel filter, the second fuelpipe and on to the first fuel pump. The supply pressure provided by the first fuel pump isnormally such that the force associated with the supply pressure is larger than the springforce. The spring device therefore preferably has a spring force that is smaller than the forceobtained by the supply pressure provided during normal operating conditions. The supply pressure can be for example higher than 5 bar during normal operating conditions, but the 8pressure may vary depending on the application, and the spring force should be adjustedaccordingly. The spring force may be adapted to correspond to the predetermined value forsupply pressure such that it is smaller than the force obtained by the supply pressure during normal operating conditions.
Further, the bypass valve is suitably adapted to be in an open position when the spring force islarger than the force associated with the supply pressure, wherein the body is positioned suchthat the passage is in fluid communication with the bypass pipe. When the provided supplypressure results in a force acting on the body which is smaller than the spring force, the fluidflows from the fuel tank through the first fuel pipe, the bypass pipe, the passage in the body,the second fuel pipe and on to the first fuel pump. The spring force is suitably larger than theforce associated with the supply pressure when the supply pressure is lower than the supplypressure, which can be e.g. 5 bar, whereby the bypass valve is thus adapted to be in an openposition when the supply pressure is below 5 bar. The predetermined value is thereby 5 bar.Of course, the supply pressure and thus the spring force can be lower or higher than 5 bar, and can be adjusted to be optimal to the vehicle or the fuel system in question.
According to a further aspect of the invention a supply pressure control device is arrangedupstream ofthe second fuel filter. The supply pressure control device suitably comprises acheck valve and a fifth fuel pipe arranged in fluid communication with the second fuel pipeand the third fuel pipe. The supply pressure control device is arranged to control the supplypressure upstream of the second filter by enabling excess fuel to flow from the third fuel pipe through the fifth fuel pipe back to the second fuel pipe.
Figure 1 schematicaliy shows a side view of a vehicle 1 cornprising a fuel systern 10 accordingto an emlaoclinient ofthe invention. The vehicle 1 cornprises an internai cornbustion engine 2connected to a gearbox fi. The gearbox 4 is also connected to the driving wheels 8 of thevfehicie 1 tiirougii an output sliaft of the gearbox (riot sliownl. The vehicie aiso cornprises aChassis 9. The vehicle 1 may be a heavy vehicle, e.g. a truck or a bus. The vehicle 1 may alternatively be a passenger car.
Figure 2 schematicaliy shows a coupling diagram for a fuel system 10 for an internalcombustion engine 2 according to an embodiment of the invention. The fuel system 10 comprises a low-pressure circuit 12 with a first fuel tank 14, a first fuel pump 16, a first fuel 9 filter 18 arranged upstream of the first fuel pump 16 and a second fuel filter 20 arrangeddownstream ofthe first fuel pump 16. A first fuel pipe 22 is arranged in fluid connection withthe first fuel tank 14 and the first fuel filter 18. A second fuel pipe 24 is arranged in fluidconnection with the first fuel filter 18 and the first fuel pump 16. A third fuel pipe 26 isarranged in fluid connection with the first fuel pump 16 and the second fuel filter 20. A fourthfuel pipe 28 is arranged in fluid connection with the second fuel filter 20 and a high-pressurecircuit of the fuel system 10, which is not shown in detail. A bypass valve 30 is arranged toallow fuel to bypass the first fuel filter 18 via a bypass pipe 32 arranged in fluid connectionwith the first fuel pipe 22 and the second fuel pipe 24. The bypass valve 30 is adapted to becontrolled based on the supply pressure downstream of the first fuel pump 16. ln this way, itcan be ensured that fuel with sufficient supply pressure is provided to the high-pressure circuitand the internal combustion engine 2 can receive sufficient amount of fuel even when the firstfuel filter is clogged. The risk for operational disruptions of the internal combustion engine 2 is thereby reduced.
The first fuel filter 18 is suitably a water separating fuel filter. Since the first fuel filter 18 is arranged upstream ofthe first fuel pump 16, the first fuel filter 18 constitutes a suction filter.
The fourth fuel pipe 28 is in fluid connection with the high-pressure circuit ofthe fuel system10. This is symbolised by the dotted line in the figure. The fuel system 10 may comprisecomponents not shown in this figure according to common fuel systems. For example, thelow-pressure circuit 12 may comprise more than one fuel tank 14 and/or more than one fuel pump 16.
A supply pressure control device 40 is arranged upstream of the second fuel filter 20. Thesupply pressure control device 40 comprises a check valve 42 and a fifth fuel pipe 44 arrangedin fluid communication with the second fuel pipe 24 and the third fuel pipe 26. The supplypressure control device 40 is arranged to control the supply pressure upstream of the secondfuel filter 20 by enabling excess fuel to flow from the third fuel pipe 26 through the fifth fuel pipe 44 back to the second fuel pipe 24.
The bypass valve 30 is arranged such that when the bypass valve 30 is in an open position thefuel flows from the fuel tank 14 through the first fuel pipe 22, the bypass pipe 32 and the bypass valve 30 to the second fuel pipe 24 and on to the first fuel pump 16. When the bypass valve 30 is in a closed position the fuel suitably flows from the fuel tank 14 through the firstfuel pipe 22 and the first fuel filter 18 to the second fuel pipe 24 and the first fuel pump 16.The bypass valve 30 is thus arranged to fluidly connect or disconnect the first fuel pipe 22 with the second fuel pipe 24 via the bypass pipe 32.
The bypass valve 30 according to one embodiment ofthe invention is shown in more detail inFig. 3a and 3b. Other constructions would of course be possible. The bypass valve is ahydraulic valve affected by the supply pressure downstream of the first fuel pump 16. Thebypass valve 30 is self-adjusting and a passive control of the bypass valve 30 is therebyachieved. The bypass valve 30 is a spring loaded valve connected to the bypass pipe 32, thesecond fuel pipe 24 and the fourth fuel pipe 28 downstream ofthe first fuel pump 16. Thebypass valve 30 is connected to the fourth fuel pipe 28 via a control conduit 50 arranged influid connection with the fuel pipe 28. The supply pressure in the control conduit 50 is thusessentially the same as in the fourth fuel pipe 28. The bypass valve 30 is adapted to becontrolled based on the supply pressure downstream of the second fuel filter 20. By using thesupply pressure downstream of the second fuel filter 20 it is the actual supply pressure which is provided to the high-pressure circuit that is controlling the bypass valve 30.
As mentioned above, and as shown by Fig. 3a and 3b, the bypass valve 30 is a spring loadedhydraulic valve arranged in fluid communication with the bypass pipe 32, the second fuel pipe24 and the control conduit 50. The bypass valve 30 comprises a housing 60 and inside thehousing 60 a spring device 62 and a body 64 are arranged. The spring device 62 is arranged ona first side ofthe body 64 inside the housing 60 and an opening 66 in the housing facing thecontrol conduit 50 is on a second side ofthe body 64. The spring device 62 is thus acting with aspring force FS on a first side 68' of the body 64 and a force associated with the supplypressure Fp is acting on a second side 68" of the body 64. This is illustrated by arrows in Fig. 3aand 3b. The second side 68" is opposite to the first side 68'. The spring force FS and the forceassociated with the supply pressure Fp are thus acting on the body 64 in opposing directions.The force associated with the supply pressure Fp acting on the second side 68" of the body 64 depends on the supply pressure and the area A of the second side 68" of the body 64.
The body 64 is arranged inside the housing 60 such that the first side 68' of the body 64 and the housing 60 define a cavity 70 in which the spring device 62 is arranged. The body 64 11 suitably extends longitudinally between the first side 68' and the second side 68". The body 64is arranged to be moved in the longitudinal direction by means of the spring force FS and/orthe force associated with the supply pressure Fp. The body 64 thus acts as a piston inside thehousing 60. When the force associated with the supply pressure Fp moves the body 64, thespring device 62 is compressed and the cavity 70 is decreased. When the spring force FS movesthe body 64, the spring device 62 extracts and the cavity 70 is expanded. A ventingarrangement 72 is arranged in f|uid connection with the cavity 70. The air inside the cavity 70may thereby be vented and enable movement of the body 64. The venting arrangement 72 issuitably a venting conduit arranged in f|uid connection with the cavity 70 and the bypass pipe 32.
The body comprises a passage 74 and the passage 74 extends perpendicularly to the longitudinal extension of the body 64. The passage 74 is a through hole.
Figure 3a shows the bypass valve 30 in an open position. The body 64 is thus positioned suchthat the passage 74 is in f|uid communication with the bypass pipe 32. The bypass valve 30 isin the open position when the spring force FS is larger than the force associated with thesupply pressure Fp and the spring device 62 is thus in an extracted state. When the providedsupply pressure results in a force Fp acting on the body 64 which is smaller than the springforce FS, the f|uid flows from the fuel tank 14 through the first fuel pipe 22, the bypass pipe 32,the passage 74 in the body 64, the second fuel pipe 24 and on to the first fuel pump 16. This isillustrated with arrows. The spring force FS is larger than the force associated with the supplypressure Fp when the first fuel filter 18 is clogged. The spring force FS is suitably larger than theforce associated with the supply pressure Fp when the supply pressure is below a predetermined value which can for example be 5 bar.
Figure 3b shows the bypass valve 30 in a closed position. The body 64 is thereby positionedsuch that the passage 74 is not in f|uid communication with the bypass pipe 32. The passage74 is thus displaced relative to the bypass pipe 32. The bypass valve 30 is in the closed positionwhen the spring force FS is smaller than the force associated with the supply pressure Fp andthe spring device 62 is thus in a compressed state. When the provided supply pressure resultsin a force Fp acting on the body 64 which is larger than the spring force FS, the f|uid flows from the fuel tank 14 through the first fuel pipe 22, the first fuel filter 18, the second fuel pipe 24 12and on to the first fuel pump 16. The supply pressure provided by the first fuel pump 16 isnormally such that the force associated with the supply pressure Fp is larger than the springforce FS. The spring device 62 therefore preferably includes a spring force FS which is smallerthan the force obtained by the supply pressure Fp provided during normal operating conditions.
Further variations of the invention are possible within the scope defined in the appended claims.

Claims (10)

13 i
1. A fuel system for an internal combustion engine (2) comprising a low-pressure circuit (12)with a first fuel tank (14), a first fuel pump (16), a first fuel filter (18) arranged upstream of thefirst fuel pump (16) and a second fuel filter (20) arranged downstream of the first fuel pump(16), wherein a first fuel pipe (22) is arranged in fluid connection with the first fuel tank (14)and the first fuel filter (18), a second fuel pipe (24) is arranged in with the first fuel filter (18)and the first fuel pump (16), a third fuel pipe (26) is arranged in fluid connection with the firstfuel pump (16) and the second fuel filter (20), and a fourth fuel pipe (28) is arranged in fluidconnection with the second fuel filter (20) and a high-pressure circuit of the fuel system (10),characterized in that a bypass valve (30) is arranged to allow fuel to bypass the first fuel filter(18) via a bypass pipe (32) arranged in fluid connection with the first fuel pipe (22) and thesecond fuel pipe (24), wherein the bypass valve (30) is adapted to be controlled based on the supply pressure downstream of the first fuel pump (16).
2. A fuel system according to claim 1, characterized in that the bypass valve (30) is adapted tobe controlled based on the supply pressure downstream ofthe second fuel filter (20) in the fourth fuel pipe (28).
3. A fuel system according to claim 1 or 2, characterized in that the bypass valve (30) isadapted to be controlled to a closed position, such that the fuel flows through the first fuel filter (18), when the supply pressure is above a predetermined value.
4. A fuel system according to any of the preceding claims, characterized in that the bypassvalve (30) is adapted to be controlled to an open position, such that the fuel flows through the bypass pipe (32), when the supply pressure is below a predetermined value.
5. A fuel system according to any of the preceding claims, characterized in that the bypass valve (30) is a hydraulic valve.
6. A fuel system according to claim 5, characterized in that the bypass valve (30) is a springloaded valve connected to the bypass pipe (32) and a fuel pipe (26; 28) downstream of thefirst fuel pump (16), wherein a body (64) with a passage (74) is arranged such that a springdevice (62) is acting with a spring force (FS) on a first side (68') ofthe body (64) and a force associated with the supply pressure (Fp) is acting on a second side (68") of the body (64).
7. 147. A fuel system according to claim 6, characterized in that the bypass valve (30) is in a closedposition when the spring force (FS) is smaller than the force associated with the supplypressure (Fp), wherein the body is positioned such that the passage (74) is not in fluid communication with the bypass pipe (32).
8. A fuel system according to claim 6 or 7, characterized in that the bypass valve (30) is in anopen position when the spring force (FS) is larger than the force associated with the supplypressure (Fp), wherein the body (64) is positioned such that the passage (74) is in fluid communication with the bypass pipe (32).
9. An internal combustion engine system characterized in that it comprises a fuel system (10) according to any of the claims 1-8.
10. A vehicle characterized in that it comprises a fuel system (10) according to any of the claims 1-8.
SE1550935A 2015-07-02 2015-07-02 Fuel system for an internal combustion engine SE539340C2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
SE1550935A SE539340C2 (en) 2015-07-02 2015-07-02 Fuel system for an internal combustion engine
DE112016002669.2T DE112016002669T5 (en) 2015-07-02 2016-06-28 Fuel system for an internal combustion engine
PCT/SE2016/050649 WO2017003359A1 (en) 2015-07-02 2016-06-28 Fuel system for an internal combustion engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE1550935A SE539340C2 (en) 2015-07-02 2015-07-02 Fuel system for an internal combustion engine

Publications (2)

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SE1550935A1 true SE1550935A1 (en) 2017-01-03
SE539340C2 SE539340C2 (en) 2017-07-11

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SE (1) SE539340C2 (en)
WO (1) WO2017003359A1 (en)

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Publication number Priority date Publication date Assignee Title
DE102021002134B3 (en) 2021-04-22 2022-09-29 Daimler Truck AG Fuel system for an internal combustion engine, in particular a motor vehicle, and motor vehicle with such a fuel system
DE102021002132B3 (en) 2021-04-22 2022-09-29 Daimler Truck AG Pressure control valve for setting, in particular for controlling, a pressure of a fuel and a fuel system for an internal combustion engine
DE102021002127B3 (en) 2021-04-22 2022-09-29 Daimler Truck AG Fuel system for an internal combustion engine, in particular a motor vehicle, and motor vehicle with such a fuel system

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4346689A (en) * 1980-12-09 1982-08-31 Neely Noah A Controlled fuel injection system
DE10013905A1 (en) * 2000-03-21 2001-09-27 Mannesmann Vdo Ag Conveying device for conveying fuel
JP4821860B2 (en) * 2009-02-04 2011-11-24 株式会社デンソー Fuel filtration device

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WO2017003359A1 (en) 2017-01-05
DE112016002669T5 (en) 2018-03-08
SE539340C2 (en) 2017-07-11

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