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
  • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
  • F02M55/002—Arrangement of leakage or drain conduits in or from injectors
• • 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
  • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
  • F02M55/007—Venting 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
  • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
  • F02M55/02—Conduits between injection pumps and injectors, e.g. conduits between pump and common-rail or conduits between common-rail and injectors
  • F02M55/025—Common rails

Definitions

• the invention relates to a fuel injection arrangement according to the preamble to patent claim 1.
• the object of the invention is to provide for a fuel system a fuel injection arrangement which ensure reliable functioning of the engine's fuel system and at the same time eliminates the problems which are caused by the fact that the fuel contains gases.
• a further object is to achieve this by simple means.
• the fuel system being vented by means of a constriction between the pressurised feed side of the system and its return side, which is at atmospheric pressure.
• the constriction is optimised to allow a sufficient amount of air/fuel to pass through it and back to the tank without having for this purpose to reduce the pressure on the feed side to an unacceptably low level in operating situations.
• the constriction has primarily three functions:
• the arrangement adopted makes it possible to vent the fuel system continuously without causing fuel spillage problems.
• the venting point is with advantage placed high in the fuel system so as to create the best possible venting conditions.
• the fuel system also becomes very easy to vent in connection with such operations as repairs or filter changing. Further features and advantages of the solution according to the invention are indicated by the description below and the other patent claims.
• Fig.1 depicts schematically a fuel system for a combustion engine with a fuel injection arrangement according to the invention.
• a fuel system 1 for a motor vehicle with a multi-cylinder engine is provided with a fuel injection arrangement 2 in which there is for each engine cylinder a fuel injector 3.
• the engine (not depicted) is a six-cylinder combustion engine and there are therefore six fuel injectors 3 which are here arranged in two groups each comprising three fuel injectors.
• the engine may for example take the form of a diesel engine intended to drive a heavy-duty vehicle such as a truck or a bus.
• the fuel injection arrangement 2 is supplied with fuel via a pressure line 4 from a pump 5 which is itself connected to a fuel tank 7 via a suction line 6.
• the suction line 6 contains in this order a first filter 8, an auxiliary pump 9, a second filter 10 and a heat exchanger 11 , via which heat exchanger 11 fuel is used for cooling a here undepicted electronic control device.
• the pressure line 4 incorporates a third filter 12 which is finer than the second filter 10, which is itself finer than the first filter 8.
• a return line 13 which incorporates a fuel cooler 14 leads back from the fuel injection arrangement 2 to the tank 7.
• the pressure line 4 leads into a feed duct 15 in the fuel injection arrangement 2 via an emergency shutoff valve 16 which is normally open.
• a pressure regulator 17 maintains the pressure in the feed duct 15 at a predetermined level and returns any overpressure fuel to the suction line 6 via a return line 18.
• Each group of fuel injectors 3 is supplied, via a feed line 19 and a feed valve 20 situated therein, with fuel for combustion.
• the injectors 3 have for each group a check valve 28 situated in the feed line 19. This check valve 28 opens at a predetermined pressure, advantageously 0.15 MPa.
• the feed valve 20 also incorporates a check valve 29.
• each group of fuel injectors 3 is supplied, via a control line 21 and a control valve 22 situated therein, with control fuel to control the time and duration of fuel injection.
• connection 24 with a constriction 25 via which the feed duct 15 can be vented.
• the pressure line 4 communicates with the return line 13 via a line 26 with a pressure regulator 27.
• the constriction 25 may with advantage take the form of a separate orifice with a predetermined diameter, which orifice may be screwed firmly into an aperture from the feed duct.
• the fuel injectors 3 are of the type called unit injector in which the high pressure required for fuel injection is created in the respective injector, which has for the purpose pump elements which in a conventional manner are acted upon mechanically by a drive mechanism incorporating pushrods, rocker arms and an engine-driven camshaft. This arrangement is well-known and is therefore not described in detail here.
• the emergency shutoff valve 16 is open so that the pump 5 can feed fuel into the fuel duct 15.
• the pressure controller 17 maintains the fuel pressure at a predetermined level, e.g. about 1.7 MPa (250 psi).
• the normally closed feed valves 20 and control valves 22 are electronically activated via a fuel control device (not depicted) so that the fuel injectors receive the intended amount of fuel at the correct time and can inject the correct amount of fuel at the correct time.
• connection 24 there is between the feed duct 15 and the return line 13 a connection 24 with a constriction 25 makes it possible to effectively vent the fuel before it reaches the valves 20, 22 and the fuel injectors 3.
• the constriction 25 may take the form of a hole with diameter approx. 0.25 mm in an orifice in the connection 24. If the hole is too large, problems occur during starting owing to low temperature in that too much leakage makes it difficult to build up a sufficiently high pressure in the feed duct 15. If on the contrary the hole is too small, it becomes difficult during repairs, filter changing or emptying of the fuel system to repressurise the latter manually by means of the auxiliary pump 9. Continuous venting reduces the risk of operational malfunctions and undesired power increase. It also becomes no longer necessary to have a special venting screw for venting on the occasion of such operations as filter changing and manual pumping. Fuel spillage is prevented.
• the emergency shutoff valve 16 is directed to the closed position and thereby quickly shuts off the fuel supply.
• the fuel may be led past the fuel injection arrangement 2 and back to the tank 7 via the line 26 and the pressure regulator 27, which may, for example, open at about 2.4 MPa (350 psi).
• the constriction 25 may with advantage be incorporated in a housing containing the valves 20 and 22 between the pressure side and the return side.
• the size of the constriction may of course be selected according to each particular case, but the intention is that it should be easy for air and other gases to escape, whereas fuel should only be able to escape to a minor extent.
• the link between the connection 24 and the feed duct 15 it is desirable for the link between the connection 24 and the feed duct 15 to be situated as high as possible, and the valves 20 and 22 should also be situated as close as possible to the feed duct 15.
• the invention may, within the scope of what is indicated in the patent claims, be modified and embodied otherwise than as indicated in the example described above.
• the engine may take the form of an engine driven by a mixture of diesel fuel and alcohol.
• the engine may also be used for other purposes than for driving a vehicle, e.g. it may be used as an industrial engine for driving a generator set, a pump or a watercraft.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fuel-Injection Apparatus (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20413060

Family Applications (1)

Country Status (3)

Cited By (1)

Citations (5)

• 1998
  • 1998-10-23 SE SE9803629A patent/SE521406C2/sv not_active IP Right Cessation
• 1999
  • 1999-10-18 WO PCT/SE1999/001872 patent/WO2000028207A1/en active Application Filing
  • 1999-10-18 DE DE19983617T patent/DE19983617T1/de not_active Withdrawn

Patent Citations (5)

Non-Patent Citations (1)

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