EP0903491A2 - Kraftstoffeinspritzkreislauf für eine Direkteinspritzbrennkraftmaschine - Google Patents

Kraftstoffeinspritzkreislauf für eine Direkteinspritzbrennkraftmaschine Download PDF

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Publication number
EP0903491A2
EP0903491A2 EP98402189A EP98402189A EP0903491A2 EP 0903491 A2 EP0903491 A2 EP 0903491A2 EP 98402189 A EP98402189 A EP 98402189A EP 98402189 A EP98402189 A EP 98402189A EP 0903491 A2 EP0903491 A2 EP 0903491A2
Authority
EP
European Patent Office
Prior art keywords
needle
chamber
pressure
fuel
injection circuit
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP98402189A
Other languages
English (en)
French (fr)
Other versions
EP0903491A3 (de
Inventor
Bertrand Hauet
Christian Ozenfant
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Renault SAS
Original Assignee
Renault SA
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 Renault SA filed Critical Renault SA
Publication of EP0903491A2 publication Critical patent/EP0903491A2/de
Publication of EP0903491A3 publication Critical patent/EP0903491A3/de
Withdrawn legal-status Critical Current

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    • 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
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/38—Pumps characterised by adaptations to special uses or conditions
    • F02M59/42—Pumps characterised by adaptations to special uses or conditions for starting of engines
    • 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
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/02—Fuel-injection apparatus having several injectors fed by a common pumping element, or having several pumping elements feeding a common injector; Fuel-injection apparatus having provisions for cutting-out pumps, pumping elements, or injectors; Fuel-injection apparatus having provisions for variably interconnecting pumping elements and injectors alternatively
    • F02M63/0225—Fuel-injection apparatus having a common rail feeding several injectors ; Means for varying pressure in common rails; Pumps feeding common rails

Definitions

  • the invention relates to a fuel injection circuit. for an internal combustion engine and direct injection.
  • the invention relates more particularly to a circuit injection system for an internal combustion engine and direct injection, of the type comprising at least one injector which is supplied with fuel under high pressure by a pipe connected to the outlet of a high pressure pump the entrance of which is itself connected, by a conduit, to a low pressure pump that draws fuel from a Fuel tank.
  • the fuel injectors are calibrated for operate optimally when supplied with fuel at a pressure equal to a nominal pressure.
  • the injection circuits for engines with direct injection must include a high pump pressure capable of delivering fuel under such supply pressure.
  • the injection circuit therefore comprises a first low pressure pump, called booster pump, which feeds a high pressure pump which feeds directly the injectors.
  • the injectors are supplied with fuel at a pressure below their nominal pressure for which they are calibrated, which on the one hand requires significantly increase the length of time injection and, on the other hand, which prevents having a good control of the geometry of the injected fuel jet and the degree of spraying.
  • the rise in pressure of the high pump pressure is further slowed down because it provides, simultaneously, a flow of fuel towards the injectors.
  • the invention proposes a new design of a circuit fuel injection, characterized in that the circuit includes means for closing the outlet of the pump high pressure as long as the pressure supplied by it does not reaches a threshold pressure.
  • FIG. 1 shows an injection circuit for fuel 10 for an internal combustion engine (not shown) and direct injection.
  • the invention is particularly applicable to the direct injection and spark ignition engines.
  • the injection circuit 10 is intended to supply fuel under pressure from injectors 12 with fuel taken from a tank 14.
  • the supply circuit 10 includes a first low pressure pump 16, also called booster pump, which is for example immersed in the reservoir 14 and which is driven by an electric motor 18 so as to provide fuel under low pressure, through a conduit 20, at the inlet 22 of a high pressure pump 24.
  • the high pressure pump 24 is preferably driven by the internal combustion engine, for example by the crankshaft or by a camshaft.
  • the output 26 of the high pressure pump 24 supplies the injectors 12 via a pipeline supply 28.
  • the injection circuit 10 includes means which allow shut off the outlet 26 of the high pressure pump 24 as long as the fuel pressure supplied by this pump 24 has not reaches a predetermined threshold level.
  • a 30 sequence valve is interposed in line 28 a 30 sequence valve.
  • This 30 sequence valve is normally closed to prevent traffic fuel between an upstream section 32 and a downstream section 34 of line 28.
  • the sequence valve 30 is only opened when the fuel pressure in the upstream section 32, so the fuel pressure supplied by the high pump pressure 24, has reached a predetermined threshold level.
  • a relief valve 36 is provided which is fitted as a diversion in the downstream section 34 and which allows the return of fuel to tank 14 in the event of pressure excessive in line 28.
  • the high pump pressure 24 is first of all rotated without having to provide fuel flow since its outlet 26 is located closed by the sequence valve 30.
  • the pressure rise of the high pressure pump 24 is fast and when it has reached a threshold level predetermined, the valve 30 opens and the injectors 12 are supplied with fuel under sufficient pressure to allow them to inject fuel into the cylinders in good conditions allowing easy combustion of the fuel.
  • the relief valve 36 is arranged downstream of the sequence valve 30.
  • valve 36 upstream of the discharge valve 30, which in particular allows better protect the high pressure pump from possible failure, for example of valve 30.
  • FIGS. 3 and 4 show a device 38 which combines a simple and compact valve sequence 30 and a relief valve 36 in the same valve body 40 which forms a body for regulating the fuel supply pressure.
  • the regulation 38 includes an input channel 42 and a outlet 44 which are arranged in the valve body 40, which are intended to be connected respectively to the upstream sections 32 and downstream 34 of the pipe 28, and which each open out respectively in a first 46 and in a second 48 chamber fitted in the valve body 40.
  • the first 46 and the second 48 rooms are cylindrical of revolution and they are separated one of the other by a transverse wall 50 in which is an orifice which allows the two rooms to communicate with each other and that forms a seat 52 for a needle 54 mounted movably in the valve body 40.
  • Needle 54 in the shape of a pointed truncated cone axially forward, extends axially forward from a front end of a needle head 58 which is mounted sliding in a cylindrical housing 60 of the valve body 40.
  • the front end of the needle head 58 defines sealingly, towards the rear, the first chamber 46 which is connected to the upstream section 32 of the pipe 28, which thus has a variable volume depending on the position axial of the needle head 58 in its housing 60.
  • the second chamber 48 is also of variable volume and it is delimited at the front by an axial end face rear of a stepped piston 62 which is slidably mounted axially in a corresponding stepped bore 64.
  • the piston stepped 62 thus comprises a rear section 61 of small diameter and a front section 63 of large diameter, both cylindrical of revolution.
  • a front axial end face of the front section 63 of the piston 62 delimits in the valve body 40 a third variable volume chamber 66 which is connected by a tube 68 to the first chamber 46 so that the pressure of fluid in the third chamber 66 is equal to that which prevails in the first chamber 46, that is to say equal to the pressure fuel supplied by the high pressure pump 24.
  • Each of the sections 61, 63 of the piston 62 slides from tightly in the corresponding part of bore 64 thanks to a seal 65, 67.
  • fuel may pass through one seals and accumulate in the part of the bore which is between the two seals 65, 67 which are carried by the piston 62.
  • there is provision for an evacuation of fuel 69 which is connected to the fuel tank 14 and which opens into a transverse annular face of the body of valve 40 which delimits the two parts of different diameters of bore 64. The infiltrated fuel is therefore evacuated to the tank 14.
  • piston 62 and the needle head 58 can cooperate with each other in pushing according to the axial direction by a push rod 70 which extends axially between the rear axial end face of the piston 62 and a front end of the needle 64, through the orifice forming a seat 52.
  • sequence valve 30 prevents feed fuel injectors 12.
  • the high pump pressure 24 is rotated and begins to charge fuel, it is received in the first room 46 and in the third room 66. As soon as these two chambers are filled with fuel, the pump 24 has more to deliver fuel and it can go up in pressure very fast way.
  • the pressurized fluid then flows between the needle 54 and seat 52 to first fill the second chamber 58 then flow through the outlet channel 44 in direction of the downstream section 34 of the pipeline 28 and injectors 12.
  • the cross section of the third chamber 66 is greater than that of the second chamber 48, and the fuel pressure in the second chamber 48 can only exceed that in the third chamber 66, so that the resulting from the actions of fuel under pressure on the piston 62 is directed axially towards the rear in the direction of a opening of the needle 54.
  • the cross sections of the first 46 and the second 48 room are equal so that, when the needle is open, the action of each of the fluids contained in the two chambers on the needle body, formed of the needle head 58 and the piston 62, is zero.
  • valve body 40 incorporates the relief valve 36 which limits the fuel pressure in the downstream section 34 of the line 28, according to the configuration of circuit 10 in figure 1, which therefore protects the injectors against excessive pressure.
  • the relief valve 36 has a auxiliary chamber 74 which is connected by a first pipe 76 to the outlet channel 44 of the valve 30 and by a second line 78 to the vehicle tank 14.
  • a frusto-conical shutter 80 is stressed, for example by an elastic washer of Belleville 82 type, in support against a corresponding frustoconical seat formed at the outlet of the first pipe 76 in the auxiliary chamber 74.
  • the fuel under pressure exerts a force on the shutter 80 greater than that exerted by the elastic washer 82, which forces the opening of the relief valve 36, as illustrated in the Figure 4, allowing fuel to reach directly the reservoir 14 by limiting the pressure in the outlet channel 44 of the sequence valve 30.
  • the relief valve 36 opens only for a pressure higher than normal injector supply pressure 12 so that in normal operation of circuit 10, the needle 54 is open and valve 36 is closed, contrary to what is illustrated in figure 4.
  • circuit 10 fuel injection system has a non-return valve 84 which is interposed in line 28 so as to delimit a upstream section 32 of a downstream section 34 and which prevents any fluid circulation in line 28 from downstream to upstream.
  • a pressure intensifier 86 is mounted bypassing the high pressure pump 24 and the valve non-return valve 84, between line 20 which connects the pump to low pressure 16 at the high pressure pump 24 and the downstream section 34 of the line 28.
  • the pressure intensifier 86 which is more precisely illustrated in FIG. 6, is produced under the in the form of a stepped piston 88 which is slidably mounted in a corresponding stepped bore 90 formed in a body of multiplier 92.
  • the piston 88 thus comprises a rear section 93 of large diameter which delimits, at the front, a rear chamber 94 with variable volume, and a front section 96 of small diameter which delimits, at the rear, a corresponding front chamber 98.
  • the rear chamber 94 is connected to the conduit 20, in upstream of the high pressure pump 24, while the chamber before 98 is connected to the downstream section 34 of the pipe 28, in downstream of the pump 24.
  • the boost pressure is communicated to the chamber rear 94 and there is exerted on the piston 62 a pressure equal to this booster pressure multiplied by the section area rear 93 of large diameter of the piston 62.
  • the piston 62 exerts on the fuel contained in the chamber before 98 an effort which results in a pressure higher than that prevailing in the rear chamber 94, in the ratio of the effective surfaces respective of the two chambers 98, 94.
  • non-return valve 84 opens and the fuel supply to the injectors 12 is then directly performed by the high pressure pump 24.
  • the piston 88 of the pressure intensifier 86 moves axially backwards towards its initial position, thus allowing the front chamber 98 to fill with fuel for the next start of the engine.
  • the backward movement piston 88 can be assisted by a compression spring 100 which is interposed between a front face 102 rear section 93 of piston 88 and an annular transverse face 104 turned towards the rear of bore 90 which delimits the two parts of different diameters of this bore 90.
  • an evacuation 106 of fuel which opens into the annular face 104 to avoid fuel that infiltrates from the rear chamber, the along the rear section 93 of the piston 88, does not hinder displacements of the piston 88.
  • This evacuation 106 is connected to the fuel tank 14, and it allows for example to provide for a brief seal between the rear section 93 piston 88 and the corresponding part of bore 90.
  • This second embodiment of the invention is therefore particularly advantageous in that it makes it possible to supply the injectors 12 with fuel under sufficient pressure even before the high pressure pump 24 has reached a such operating pressure.

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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)
EP98402189A 1997-09-18 1998-09-04 Kraftstoffeinspritzkreislauf für eine Direkteinspritzbrennkraftmaschine Withdrawn EP0903491A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9711653 1997-09-18
FR9711653A FR2768465B1 (fr) 1997-09-18 1997-09-18 Circuit d'injection de carburant pour un moteur a combustion interne et a injection directe

Publications (2)

Publication Number Publication Date
EP0903491A2 true EP0903491A2 (de) 1999-03-24
EP0903491A3 EP0903491A3 (de) 1999-12-29

Family

ID=9511240

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98402189A Withdrawn EP0903491A3 (de) 1997-09-18 1998-09-04 Kraftstoffeinspritzkreislauf für eine Direkteinspritzbrennkraftmaschine

Country Status (2)

Country Link
EP (1) EP0903491A3 (de)
FR (1) FR2768465B1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2798166A1 (fr) * 1999-09-02 2001-03-09 Siemens Ag Dispositif d'injection pour moteur a combustion interne
WO2012089372A1 (de) * 2010-12-27 2012-07-05 Robert Bosch Gmbh Hydraulischer druckübersetzer

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB552725A (en) * 1941-10-17 1943-04-21 Lucas Ltd Joseph Improvements relating to liquid-fuel injection means for prime movers
JPS5725157U (de) * 1980-07-18 1982-02-09
AT388030B (de) * 1982-02-12 1989-04-25 Steyr Daimler Puch Ag Kraftstoffeinspritzanlage fuer eine elektrische, ein startschloss umfassende anlasseinrichtung aufweisende kraftfahrzeug-dieselmotoren
DE69218326T2 (de) * 1991-01-14 1997-08-28 Denso Corp Druckakkumulier-kraftstoffeinspritzvorrichtung
JPH07167009A (ja) * 1993-12-14 1995-07-04 Yamaha Motor Co Ltd エンジンへの燃料供給装置

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2798166A1 (fr) * 1999-09-02 2001-03-09 Siemens Ag Dispositif d'injection pour moteur a combustion interne
WO2012089372A1 (de) * 2010-12-27 2012-07-05 Robert Bosch Gmbh Hydraulischer druckübersetzer

Also Published As

Publication number Publication date
FR2768465B1 (fr) 1999-10-29
EP0903491A3 (de) 1999-12-29
FR2768465A1 (fr) 1999-03-19

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