SE1451361A1

SE1451361A1 - A fuel system for an internal combustion engine

Info

Publication number: SE1451361A1
Application number: SE1451361A
Authority: SE
Inventors: Pål Axelsson
Original assignee: Scania Cv Ab
Priority date: 2014-11-14
Filing date: 2014-11-14
Publication date: 2016-05-15
Also published as: DE102015014270A1; DE102015014270B4; SE539811C2

Abstract

13 Abstract The invention relates to a fuel system for an internal combustion engine (300),comprising at least one fuel rail (210), at least one fuel pipe (230) fluidlyconnected to the at least one fuel rail (210) and connector means (240)sealingly connecting the at least one fuel pipe (230) to the first fuel rail (210),wherein the at least one fuel rail (210) comprises a high pressure fuel rail (212)accommodating a first space (214) and an outer casing (216) enclosing thehigh pressure fuel rail (212), wherein a second space (218) is formed betweenthe outer casing (216) and the high pressure fuel rail (212). The connectormeans (240) is fluidly connected to the second space (218) such that fuelleaking from the at least one fuel pipe (230) is led to the second space (218)through the connector means (240), and a leak detection unit (250) is arranged at the outer casing (216) in connection to the second space (218).The invention also relates to a combustion engine (300) comprising such a fuel system (200), a vehicle (100) comprising such a fuel system (200) and a powerstation (110) comprising such a fuel system (200). (Pig. 2)

Description

A fuel system for an internal combustion engine TECHNICAL FIELD The present invention relates to a fuel system for an internal combustionengine according to the preamble of claim 1. The invention also relates to aninternal combustion engine comprising such a fuel system according to claim8, a vehicle comprising such a fuel system according to claim 9 and a powerstation comprising such a fuel system according to claim 10.

BACKGROUND in order to sefeiy supply iuel to an internal conthtistion engine it is importantthet iuei ieakeges that iriey occur ere tietected. A tuei ieekage rney prevent thefuel front reaching the internal coinhustion engine tfvhich rnay seriousiy affectthe cornoustion engine. Leairirrig fuel is else a fire hazard end en environrnenteihazard. ln nfierine appiicetioiis vvhere the fuel systern is encloseci ifvithin thernerine vessel it is speeillcelly irnportant to detect fuel leakeges in order to prevent files.

There are known solutions where ciouole~walied fuel pipes ere used in order iocoliect end detect eny tuei ieaited ironi the inner pipe in the space between theinner pipe end the outer pipe. Document US 201 2/GG05297 Ai discioses e fuelsystem with a singie-ifiraiieci coinrnon rail and a plureiity of douhiewelied iueipipes, where eech deuhie-weiied fuel pipe cornprises a leak centeinrnentpassage, At the interface between each fuel pipe and the common reil eieaitege drein cennector is arrenged end a drein pipe is tiuidly coupied to theieekage cirein connectors. A tuei ieekage cietector is errengeoi in connection tothe drein pipe. Document US Qui âfuuußâe? Ai thus discioses a safe fuelsystern, out it requires several eddiiionel components and is oornolex andhuiity.

SUMMARY OF THE INVENTION Despite known solutions in the field, there is still a need to develop a fuelsystem for an internal combustion engine, which is safe, requires a minimum of components and is space saving.

An object of the present invention is thus to achieve a fuel system for an internal combustion engine, which is safe.

Another object of the invention is to achieve a fuel system for an internal combustion engine, which requires a minimum of components.

A further object of the invention is to achieve a fuel system for an internal combustion engine, which is space-saving.

A further object of the invention is to achieve a fuel system for an internal combustion engine, which is cost effective.

The herein mentioned objects are achieved by a fuel system characterized bythe features in the characterizing part of claim 1.

The herein mentioned objects are also achieved by a combustion engine characterized by the features in the characterizing part of claim 8.

The herein mentioned objects are also achieved by a vehicle characterized bythe features in the characterizing part of claim 9.

The herein mentioned objects are also achieved by a power stationcharacterized by the features in the characterizing part of claim 10.

According to an aspect of the present invention a fuel system for an internalcombustion engine is provided, the fuel system comprising at least one fuel rail, at least one fuel pipe fluidly connected to the fuel rail and connector meanssealingly connecting the at least one fuel pipe to the fuel rail, wherein the fuelrail comprises a high pressure fuel rail accommodating a first space and anouter casing enclosing the high pressure fuel rail, wherein a second space isformed between the outer casing and the high pressure fuel rail. Theconnector means is fluidly connected to the second space such that fuelleaking from the at least one fuel pipe may be led to the second space throughthe connector means, and a leak detection unit is arranged at the outer casingin connection to the second space.

By having a fuel rail comprising a high pressure fuel rail and an outer casingand designing the connector means such that fuel leaking from the at least onefuel pipe is led to the second space a fuel system is achieved where leakingfuel may be collected in a safe way. Arranging a leak detection unit at the outercasing in connection to the second space will allow a fuel leakage to bedetected in an efficient way without the need of a plurality of additionalcomponents. This way, a fuel system is achieved, which is safe, requires a minimum of components, is space saving and cost effective.

The at least one fuel rail may be a double-walled fuel rail and is typically ahigh pressure fuel rail such as a common rail.

The at least one fuel pipe is suitably arranged such that it abuts the highpressure fuel rail and is thus fluidly connected to the first space within the high pressure fuel rail.

The connector means is preferably arranged such that it extends through afirst opening in the outer casing. A first end of the connector means is thusinside the outer casing and the second space, and a second end of theconnector means surrounds the fuel pipe outside the outer casing. A firstsealing element is preferably arranged between the connector means and theouter casing at the first opening of the outer casing. A second sealing element is preferably arranged between the connector means and the fuel pipe at thesecond end of the connector means. This way, no fuel is able to leak from theconnector means to the surroundings. lf fuel would leak from the fuel pipe itwould be collected within the connector means. The leaking fuel is then led tothe second space inside the outer casing through a channel formed between the connector means and the high pressure fuel rail.

The at least one fuel pipe is connected to the at least one fuel rail in one endand suitably comprises piezoelectric injection means at the other end. The injection means injects the fuel into the combustion engine.

According to an aspect of the present invention, at least a part of the leakdetection unit is removably arranged at the outer casing. This way, at least apart of the leak detection unit may easily be exchanged when it is no longerfunctional. Preferably the whole fuel detection unit is removably arranged atthe outer casing.

According to an aspect of the present invention the leak detection unitcomprises a pipe arranged in connection to a second opening in the outercasing, wherein a sensing element of the leak detection unit is arranged insidethe pipe and extends through the opening and into the second space. Thesensing element may be a capacitive level monitoring sensor. The pipe issuitably welded to the outer casing. The pipe is arranged at the outer casingsuch that the sensing element may detect leaking fuel collected within theouter casing. Leaking fuel may be collected in a part of the outer casingsubstantially opposite to the part of the outer casing where the connectormeans and the fuel pipe is arranged. The inside of the pipe and a part of thesensing element are preferably threaded, such that the sensing element maybe screwed into place in the pipe. A part of the sensing element is preferablyarranged outside the pipe and outside the outer casing. This way, the sensingelement is easily accessible and may thereby easily be removed for service or replacement.

According to an aspect of the present invention the at least one fuel pipe isdouble-walled and thus comprises an inner pipe and an outer pipeconcentrically arranged. The outer pipe is preferably arranged such that a gapis formed between the inner pipe and the outer pipe. The inner pipe ispreferably arranged adjacent the high pressure fuel rai| such that the innerpipe is fluidly connected to the first space. The outer pipe is arranged in f|uidconnection to the connector means and thus the second space. The outer pipeis hence shorter than the inner pipe. This way, Ieaking fuel in the gap betweenthe inner pipe and the outer pipe is led to the second space through theconnector means and a safe fuel system is achieved.

According to an aspect of the present invention the fuel system comprises twofuel rails, a first fuel rai| and a second fuel rai|. The second fuel rai| and thefirst fuel rai| are suitably identically configured and both comprise a highpressure fuel rai| and an outer casing enclosing the high pressure fuel rai|. Atleast one fuel pipe is fluidly connected to the first and second fuel rai|respectively and connector means are sealingly connecting the at least onefuel pipe to the respective fuel rai|. The first fuel rai| further comprises a leakdetection unit arranged at the outer casing in connection to the second space.

The two fuel rails are preferably connected by a connection pipe. Theconnection pipe is preferably arranged in f|uid connection to the second spaceof the first fuel rai| and the second space of the second fuel rai|. Fuel Ieakingfrom the at least one fuel pipe connected to the second fuel rai| will thus firstbe collected in the second space of the second fuel rai| and subsequently beled to the second space of the first fuel rai| through the connection pipe. Thisway, the leak detecting unit arranged at the outer casing of the first fuel rai| willdetect fuel leakages originating from the second fuel rai|.

Alternatively, a leak detecting unit is arranged at the outer casing of thesecond fuel rail in connection to the second space of the second fuel rail. Thisway, fuel leakages originating from the second fuel rail may be detected.

Further objects, advantages and novel features of the present invention willbecome apparent to one skilled in the art from the following details, and alsoby putting the invention into practice. Whereas the invention is describedbelow, it should be noted that it is not restricted to the specific detailsdescribed. Specialists having access to the teachings herein will recognisefurther applications, modifications and incorporations within other fields, whichare within the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS For fuller understanding of the present invention and further objects andadvantages of it, the detailed description set out below should be read togetherwith the accompanying drawings, in which the same reference notations denote similar items in the various diagrams, and in which: Figure 1a schematically illustrates a vehicle according to an embodiment ofthe invention; Figure 1b schematically illustrates a power station according to anembodiment of the invention; Figure 2 schematically illustrates a fuel system according to anembodiment of the invention; Figure 3a schematically illustrates a fuel system according to anotherembodiment of the invention; and Figure 3b schematically illustrates a fuel system according to a further embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS Figure 1a schematically shows a side view of a vehicle 100 comprising a fuelsystem 200 for an internal combustion engine 300 according to anembodiment of the invention. The exemplified vehicle 100 is a ship but thevehicle may be a heavy vehicle, e.g. a truck or a bus. The vehicle 100 may alternatively be a passenger car.

Figure 1b schematically shows a power station 110 comprising a fuel system200 for an internal combustion engine 300 according to an embodiment of theinvention. The power station 110 may be a generator set or a power plant or similar.

Figure 2 schenwaticaiiy shows a fuel system 200 for an internal combustionengine 300 according to an embodiment of the invention. The fuel system 200comprises at least one fuel rail 210, at least one fuel pipe 230 fluidly connectedto the fuel rail 210 and a connector means 240 sealingly connecting the atleast one fuel pipe 230 to the fuel rail 210. Only one fuel pipe 230 is shown infigure 2, however, any number of fuel pipes 230 may be connected to the fuelrail 210. The fuel pipe 230 is at its other end connected to a fuel injector (notshown) for injecting fuel into the combustion engine 300. The fuel rail 210comprises a high pressure fuel rail 212 accommodating a first space 214 forhigh pressured fuel. Fuel is supplied to the high pressure fuel rail 212 from afuel tank (not shown) by means of a fuel pump (not shown) in the fuel system200. The fuel rail 210 also comprises an outer casing 216 enclosing the high pressure fuel rail 212 and accommodating a second space 218.

The fuel pipe 230 is a double-walled fuel pipe and thus comprises an innerpipe 232 and an outer pipe 234. The inner pipe 232 is arranged such that itabuts the high pressure fuel rail 212 and is thus fluidly connected to the firstspace 214 within the high pressure fuel rail 212. The outer pipe 234 and theinner pipe 232 are concentrically arranged such that a gap 236 is formed between the inner pipe 232 and the outer pipe 234. The outer pipe 234 isarranged such that a first end 238 of the outer pipe 234 is surrounded by theconnector means 240 and the gap 236 is thus fluidly connected to the innerspace of the connector means 240. The outer pipe 234 is hence shorter thanthe inner pipe 232.

The connector means 240 connects the fuel pipe 230 and the fuel rai| 210 andis arranged such that it extends through a first opening 220 in the outer casing216. A first end of the connector means 242 is thus inside the outer casing 216and the second space 218, and a second end 244 of the connector means 240surrounds the first end 238 of the outer pipe 234 outside the outer casing 216.A first sea|ing element (not shown) is preferably arranged between theconnector means 240 and the outer casing 216 at the first opening 220 of theouter casing 216. A second sea|ing element (not shown) is preferably arrangedbetween the connector means 240 and the outer pipe 234 of the fuel pipe 230at the second end 244 of the connector means 240. This way, no fuel is able toleak from the connector means 240 to the surroundings. lf fuel would leak fromthe inner pipe 232 it would leak into the gap 236 between the inner pipe 232and the outer pipe 234 and it would be collected within the connector means240. lf the leakage is occurring in a part of the inner pipe 232 which issurrounded by the connector means 240 but not the outer pipe 234, the fuelwill leak directly into the connector means 240. The leaking fuel is then led tothe second space 218 inside the outer casing 216 through a channel 224formed between the connector means 240 and the high pressure fuel rai| 212.

A leak detection unit 250 is arranged at the outer casing 216 of the fuel rai|210, in fluid connection to the second space 218. Fuel leaking from the fuelpipe 230 is as previously mentioned collected in the second space 218 and theleak detection unit 250 thus senses the fuel and generates a warning forleakage. After that, suitable actions may be taken to correct the problem. Theleak detection unit 250 comprises a pipe 252 arranged at a second opening222 in the outer casing 216 and a sensing element 254. The sensing element 254 is arranged at least partly inside the pipe 252 and extends through thesecond opening 222 and into the second space 218. A first part 254” of thesensing element 254 extends through the second opening 222, a second part254”” of the sensing element 254 is arranged outside the pipe 252 and theouter casing 216, and a third part 254””” is connected to the pipe 252. The pipe252 is preferably threaded and the third part 254””” of the sensing element 254is likewise preferably threaded, such that the sensing element 254 may bescrewed into place inside the pipe 252. The sensing element 254 is thusremovably arranged. The pipe 252 of the leak detection unit 250 may bewelded to the outer casing 216. Alternatively, the whole leak detection unit 250is removably arranged at the outer casing 216. By arranging the leak detectionunit 250 in direct connection to the second space 218 of the double-walled fuelrail 210, a fuel system 200 is achieved, which is safe, requires a minimum of components and is space-saving.

Even though a double-walled fuel pipe 230 is described herein, the fuel pipe230 could be a single-walled fuel pipe and would then be arranged as the innerpipe 232 of the double-walled fuel pipe 230. The connector means 240 wouldthen be connected to the single-walled inner pipe but everything else would besimilar to the fuel system 200 described herein.

Figure 3a schematically shows a fuel system 200 for an internal combustionengine 300 according to an embodiment of the invention. The fuel system 200comprises a first fuel rail 210 which is configured as described in Figure 2 andfurther comprises a second fuel rail 210”. The second fuel rail 210” isconfigured as the first fuel rail 210 and a leak detection unit 250 is thusarranged at the second fuel rail 210”. The first fuel rail 210 and the second fuelrail 210” are each connected to a plurality of fuel pipes 230. The fuel pipes 230could be single-walled or double-walled. Since each fuel rail 210, 210” isequipped with a leak detection unit 250, a safe and compact fuel system 200 is achieved.

Figure 3b schematically shows a fuel system 200 for an internal combustionengine 300 according to an embodiment of the invention. The fuel system 200comprises a first fuel rail 210 which is configured as described in Figure 2 andfurther comprises a second fuel rail 210”. The second fuel rail 210” isconfigured as the first fuel rail 210 with the exception that there is no leakdetection unit 250 arranged at the second fuel rail 210”. The first fuel rail 210and the second fuel rail 210” are each connected to a plurality of fuel pipes 230which could be single-walled or double-walled.

A connection pipe 270 is arranged between the first fuel rail 210 and thesecond fuel rail 210” such that the second space 218 of the second fuel rail210” is fluidly connected to the second space 218 of the first fuel rail 210. Thisway, if a fuel leakage is occurring in association with the second fuel rail 210”,the leaking fuel will be led to the second space 218 of the first fuel rail 210 andthe leak detection unit 250 will detect the leakage. This way, only one leakdetection unit 250 is needed and a safe and cost-effective fuel system 200 isachieved.

The foregoing description of the preferred embodiments of the presentinvention is provided for illustrative and descriptive purposes. lt is not intendedto be exhaustive or to restrict the invention to the variants described. l\/lanymodifications and variations will obviously be apparent to one skilled in the art.The embodiments have been chosen and described in order best to explainthe principles of the invention and its practical applications and hence make itpossible for specialists to understand the invention for various embodimentsand with the various modifications appropriate to the intended use.

Claims

11 Claims

1. A fuel system for an internal combustion engine (300), comprising at leastone fuel rail (210), at least one fuel pipe (230) fluidly connected to the at leastone fuel rail (210) and connector means (240) sealingly connecting the at leastone fuel pipe (230) to the at least one fuel rail (210), wherein the at least onefuel rail (210) comprises a high pressure fuel rail (212) accommodating a firstspace (214) and an outer casing (216) enclosing the high pressure fuel rail(212), wherein a second space (218) is formed between the outer casing (216)and the high pressure fuel rail (212), characterized in that the connectormeans (240) is fluidly connected to the second space (218) such that fuelleaking from the at least one fuel pipe (230) is led to the second space (218)through the connector means (240), and a leak detection unit (250) is arrangedat the outer casing (216) in connection to the second space (218).

2. A fuel system according to claim 1, characterized in that at least a part ofthe leak detection unit (250) is removably arranged at the outer casing (216).

3. A fuel system according to claim 1 or 2, characterized in that the leakdetection unit (250) comprises a pipe (252) arranged in connection to aopening (222) in the outer casing (216), wherein a sensing element (254) ofthe leak detection unit (250) is arranged inside the pipe (252) and extendsthrough the opening (222) and into the second space (218).

4. A fuel system according to any of the preceding claims, characterized inthat the at least one fuel pipe (230) is double-walled and thus comprises aninner pipe (232) and an outer pipe (234) concentrically arranged.

5. A fuel system according to claim 4, characterized in that the inner pipe(232) is arranged in fluid connection to the first space (214) and the outer pipe(234) is arranged in fluid connection to the second space (218). 12

6. A fuel system according to any of the preceding claims, characterized inthat it comprises a first fuel rail (210) and a second fuel rail (210”).

7. A fuel system according to claim 6, characterized in that the two fuel rails(210, 210”) are connected by a connection pipe (270).

8. A combustion engine (300), characterized in that it comprises a fuel system(200) according to any of the claims 1-7.

9. A vehicle (100), characterized in that it comprises a fuel system (200)according to any of the claims 1-7.

10. A power station (110) characterized in that it comprises a fuel system (200) according to any of the claims 1-7.