GB2069047A - Electronically-controlled fuel injection system for an internal combustion engine - Google Patents

Electronically-controlled fuel injection system for an internal combustion engine Download PDF

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Publication number
GB2069047A
GB2069047A GB8103092A GB8103092A GB2069047A GB 2069047 A GB2069047 A GB 2069047A GB 8103092 A GB8103092 A GB 8103092A GB 8103092 A GB8103092 A GB 8103092A GB 2069047 A GB2069047 A GB 2069047A
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GB
United Kingdom
Prior art keywords
fuel
electronically
injection system
pressure supply
nozzle
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Withdrawn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
GB8103092A
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.)
MAN AG
Original Assignee
MAN Maschinenfabrik Augsburg Nuernberg AG
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 MAN Maschinenfabrik Augsburg Nuernberg AG filed Critical MAN Maschinenfabrik Augsburg Nuernberg AG
Publication of GB2069047A publication Critical patent/GB2069047A/en
Withdrawn legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M47/00Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure
    • F02M47/02Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure of accumulator-injector type, i.e. having fuel pressure of accumulator tending to open, and fuel pressure in other chamber tending to close, injection valves and having means for periodically releasing that closing pressure
    • F02M47/027Electrically actuated valves draining the chamber to release the closing pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M47/00Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure
    • F02M47/04Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure using fluid, other than fuel, for injection-valve actuation
    • F02M47/043Fluid pressure acting on injection-valve in the period of non-injection to keep it closed
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M61/00Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/16Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fuel-Injection Apparatus (AREA)
  • High-Pressure Fuel Injection Pump Control (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Abstract

The electronically-controlled fuel injection system comprises a fuel injector having an injection nozzle (2) with a movable injection needle (3) therein, a fuel pressure supply (28) for supplying fuel to the injection nozzle (3), a control pressure supply (30), and a control unit (6) for receiving engine data (8, 11) and actuating a control valve (7) arranged in the control pressure circuit (30). The control valve is a two position, three-way servo valve (7) movable to connect the control pressure supply (30) to a pressure outlet (A) of the servo valve (7) acting directly on the end of the nozzle needle (3) remote from the injection nozzle (2) so as to close the injection nozzle (2). <IMAGE>

Description

SPECIFICATION Electronically-controlled fuel injection system for an internal combustion engine This invention relates to an electronicallycontrolled fuel system for internal combustion engines, particularly but not exclusively for diesel engines.
An electronically controlled fuel injection system is disclosed in German patent publication DE-OS 25 29 933, and employs hydraulically controlled nozzle-needle actuating systems using a two-stage servo valve (4/2-way valve) and downstream control stages (step-up pistons, piston for the nozzle needle). This arrangement has the disadvantage that the masses to be accelerated, the large injurious volumes and the indirect transformation of pulses impair the operating speed of the system.
This disqualifies or at least restricts its use in control arrangements for nozzle needles of highspeed engines. The principal cause of the sluggish action in service is the third stage with the moving masses of the control needle and of the step-up pistons and with the frictional forces counteracting the movement.
An object of the present invention is to provide an electronically-controlled fuel injection system for an internal combustion engine which is simple in construction, reliable in operation and is especially suitable for high-speed engines.
The invention provides an electronicallycontrolled fuel injection system for an internal combustion engine comprising a fuel injector having an injection nozzle with a movable injection needle therein, a fuel pressure supply for supplying fuel to the injection nozzle, a control pressure supply, a control unit for receiving engine data and actuating a control valve arranged in the control pressure circuit, wherein the control valve is a 3/2-way servo valve movable to connect the control pressure to a pressure outlet of the servo valve acting directly on the end of the nozzle needle remote from the injection nozzle so as to close the injection nozzle.
The hydraulic output pressure pulse can be timed, in terms of both pressure and volume, such that the swept volume required to displace the nozzle needle corresponds to a certain travel of the nozzle needle at the nozzle. The amount of such travel is a measure of the quantity injected in unit time and varies directly with the hydraulic output pressure pulse of the servo valve. The length of injection time is determined by the duration of the given electrical input signal. This signal is varied to achieve approximately analogous injection pressure profiles and controlled variable injection quantities that relate directly to the signal.
Thus by means of the present invention it is possible to eliminate the downstream control stages of the known servo valve, i.e. of the control pistons and various step-up pistons. This minimizes the moving masses of the control system to give the system superior speed and comparatively short injection times. Thus the fuel injection system arrangement of the present invention is suitable for high-speed internal combustion engines, especially for high-speed diesel engines having relatively short control and injection times. The 3/2-way servo valve (one way for pressure, one way for return, one way for signal pressure) is simple and compact in design and very reliable operationally because of its simplicity. Thus, the need for complex muiti-way control valves is now eliminated.
In a preferred embodiment of the invention the fuel and control pressure supplies are integrated and connected to a common source of pressure, the fuel pressure supply being diverted at a point upstream of the servo valve and being fed to the injection end of the nozzle needle through a connecting line. The source of pressure can be a single, high-pressure accumulator of approximately constant working pressure which communicates with a supply reservoir through a single supply line, a storage pump and a Filter arrangement. The integrated design of the fuel and control pressure supply system makes fuel injection especially simple and reliable in operation.
In another preferred aspect of the invention, pressure regulating means are provided for the fuel and control pressure supply, permitting modulated, variable pressures to be built at the nozzle needle.
In an especially preferred aspect of the invention the nozzle needle is designed as a differential piston providing the requisite pressure difference between the upper and lower sides of the nozzle needle in cooperation with the pressure reducing or regulating elements.
In an alternative embodiment of the invention, the fuel pressure supply and control pressure supply are separate but operate at substantially equal pressures, and the nozzle needle is a differential piston. In this embodiment the pressure difference is built exclusively by the differential piston. This eliminates the need for intervening regulating elements.
In a further alternative embodiment of the invention, the fuel pressure supply and control pressure supply fuel and signal are separate and operate at different pressures and the nozzle needle is a single-acting piston.
Fuel injection is made especially simple and easy to maintain when the various constructional elements of the servo valve are separately arranged in the nozzle body. This relates to the arrangement of the electro-hydraulic amplifier stage (armature of the servo valve) and of the hydraulic power stage (pilot piston or servo valve), which when locally separated one from the other are interconnected through lines. In this fashion the servo valve with its constituent elements hydraulic pilot valve and armature -- is not an externally mounted valve unit but is arranged separately in the injection valve as an integrated unit.
The nozzle needle can optionally be a one-piece or a multi-piece construction.
In a further aspect of the present invention the differential piston, rather than being a single-piece or multi-piece construction, may optionally be replaced with a differential piston comprising a diaphragm or bellows.
Two embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is an operation diaphragm of an electronically-controlied fuel injection system according to the invention, in which a single, common source of pressure is provided for the fuel and control pressure supplies; Figure 2 is an operation diagram of an alternative embodiment of an electronicallycontrolled fuel injection system according to the invention, in which the control pressure is controlled separately from the fuel supply, and Figure 3a-c illustrate schematically different nozzle needle designs.
In Figure 1 , a constant-pressure injection system has a single pressurizing system for both fuel and control pressure supplies. A high-pressure fuel accumulator 1 6 is supplied with fuel from a fuel tank 10. In order to build and maintain a constant-level pressure in the high-pressure accumulator 16, a fuel pump 12 is provided in a fuel supply line 26, the pump 12 being continuously driven by a constant-speed motor 14.
The fuel line leading away from a high-pressure filter 15 is connected to an inlet end P of a servo valve 7 through a pressure-reiief valve 18 and a connecting line 30.
The outlet end R of the servo valve 7 serves to return the fuel to the fuel tank 10 via a fuel return line 32 between the output end R and the fuel tank 10.
A regulating valve is connected via a fuel overflow line 24 between the fuel pump 12 and the pressure-relief valve 18, and routes excess fuel to an overflow tank 22. The overflow tank 22 and the fuel tank 10 can optionally be integrated.
Using the regulating or overflow system, then, the high-pressure pump 12 can be continuously driven by motor 14 regardless of the amount and time of injection.
Upstream of the servo valve 7 the connecting line 30 branches into a further connecting line 28 connected to the inlet C adjacent the injection area 9 of an injection nozzle 2, more particularly to a fuel feed chamber 4 of a nozzle needle 3.
The nozzle needle 3 is preloaded at its upper end in the direction of injection (i.e. at the end remote from the fuel feed chamber 4, by means of a spring 5. The upper end of the nozzle needle 3 is connected directly to an output signal line 1 connected to the outlet end A of the servo valve 7.
The non-energized piston side of the nozzle needle 3 is connected to a relief line 34 communicating with a relief vessel 35.
The servo valve 7 is controlled by an electronic control unit 6 receiving nominal engine data 8 and actual engine data 11.
The servo valve 7 is a 3/2-way valve, i.e., there are three ways provided (one for pressure, one for return, one for signal pressure). The compact, dash-dotted servo valve 7 of Figure 1 is connected directly to the nozzle needle 3 of the injection nozzle 2, which in the drawing is aiso shown schematically in dash-dotted line.
Figure 1 thus shows the control circuit for a common supply line for the hydraulic pressure and the fuel circuits. The common hydraulic pressure supply is split upstream of the servo valve 7, into a fuel supply system 28 and energy supply system 30 for the servo valve 7. The hydraulic pressure acts continuously on the inlet P of the servo valve and below the nozzle needle C, bearing directly on the nozzle needle through the outlet A at the times between injection periods. In order to achieve injection, the valve is moved to the left in Figure 1 so that A and R communicate, thus relieving the upper end of the nozzle needle 3. Injection stops when the servo valve 7 is moved back to the right so that P and A communicate.This accordingly makes the opening and closing times of the nozzle needle a function solely of the dynamic behaviour of the servo valve, of the length of line, and of the volume displaced by the stroke of the needle.
Figure 2 illustrates another schematic arrangement of a fuel injection system in accordance with the present invention having two separately-controlled pressurizing systems. The pressurizing system for the fuel supply as shown on the right-hand side of Figure 2 has the same individual elements as previously described in connection with Figure 1. The servo valve 7, the electronic control unit 6 and the injection nozzle 2 are all as described for Figure 1 and the same reference numerals have been used.
The fuel supply system of Figure 2 differs from that of Figure 1 in that it communicates exclusively with the inlet end C of the fuel feed chamber 4 of the nozzle needle 3, while the servo nozzle 7 is supplied with signal pressure through a separate system shown on the left-hand side of Figure 2.
The control pressure system operates with a hydraulic fluid stored in a hydraulic reservoir 60. A hydraulic pressure circuit formed by a hydraulic fluid reservoir 66, a regulating valve 70 and a hydraulic fluid supply line 76 is fed, through a high-pressure filter 64, from a hydraulic pump 62 and communicates with the inlet end of the servo valve 7. This hydraulic pressure circuit and thus the hydraulic fluid reservoir 66, is controlled by the pressure regulating valve 70 via an overflow line 74, with excess hydraulic fluid returning to a hydraulic reservoir 72. The design and function of the sytem correspond to the elements 20, 22 and 24 of Figure 1, except that the system here operates with hydraulic liquid, not with fuel.
Figure 2 thus shows a schematic control diagram in which the hydraulic supply lines are separated from the fuel supply lines. The hydraulic pressure acts on the inlet end P of the servo valve 7, and between injection periods acts directly on the nozzle needle 3 through the outlet end A. In order to achieve injection, the valve 7 moves to correct A and R, relieving the upper end of the nozzle needle. Injection is terminated when the servo valve 7 shifts back to connect P to A.
Figures 3a, 3b and 3c show different forms of nozzle needles 3. The nozzle needle here takes the shape of different pistons providing the necessary pressure difference across the nozzle needle alone or in conjunction with additional signal pressures.
The embodiment of Figure 3a is a one-piece construction, and has a sealing ring 40. The sealing ring is formed from two elements, of which one is wear resistant and the other flexible.
The embodiment of differential piston in Figure 3b is also a one-piece construction. A resilient diaphragm or bellows 42 fixedly connected to the piston acts as an additional combined sealing element -- labyrinth and gap seal.
The embodiment in Figure 3c is a two-piece construction. Two pistons 43 and 44 of different diameters are connected together by a diaphragm or bellows 42 to form a differential piston 3. The bellows construction 42 is formed as a flexible connecting element and compensates for manufacturing tolerances.

Claims (11)

1. An electrically-controlled fuel injection system for an internal combustion engine, comprising a fuel injector having an injection nozzle with a movable injection needle therein, a fuel pressure supply for supplying fuel to the injection nozzle, a control pressure supply, a control unit for receiving engine data and actuating a control valve arranged in the control pressure circuit, wherein the control valve is a 3/2way servo valve movable to connect the control pressure supply to a pressure outlet of the servo valve acting directly on the end of the nozzle needle remote from the injection nozzle so as to close the injection nozzle.
2. An electronically-controlled fuel injection system as claimed in Claim 1, wherein the fuel pressure supply and control pressure supply are integrated and connected to a common source of pressure, the fuel pressure supply being diverted upstream of the servo valve and being fed to the injection end of the nozzle needle through a connecting line.
3. An electronically-controlled fuel injection system as claimed in Claim 1 or 2, wherein pressure regulating means are provided for the fuel and control pressure supplies.
4. An electronically-controlled fuel injection system as claimed in any one of the preceding Claims, wherein the nozzle needle is formed as a differential piston.
5. An electronically-controlled fuel injection system as claimed in Claim 1, wherein the fuel pressure supply and control pressure supply are separate but operate at substantially equal pressures, and the nozzle needle is a differential piston.
6. An electronically-controlled fuel injection system as claimed in Claim 1, wherein the fuel pressure supply and control pressure supply fuel and signal are separate and operate at different pressures and the nozzle needle is a single-acting piston.
7. An electronically-controlled fuel injection system as claimed in any one of the preceding Claims, wherein the servo valve is incorporated in a nozzle body of the fuel injector.
8. An electronically-controlled fuel injection system as claimed in any one of Claims 4 to 6, in that the nozzle needle is a one-piece design.
9. An electronically-controlled fuel injection system as claimed in any one of Claims 4 to 6, wherein the nozzle needle comprises two parts of different diameter connected by a bellows.
10. An electronically-controlled fuel injection system substantially as herein described with reference to any one of the embodiments shown in the accompanying drawings.
11. An internal combustion engine having an electronically-controlled fuel injection system as claimed in any one of the preceding claims.
GB8103092A 1980-02-02 1981-02-02 Electronically-controlled fuel injection system for an internal combustion engine Withdrawn GB2069047A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19803003904 DE3003904A1 (en) 1980-02-02 1980-02-02 ELECTRONICALLY CONTROLLED FUEL INJECTION FOR INTERNAL COMBUSTION ENGINES

Publications (1)

Publication Number Publication Date
GB2069047A true GB2069047A (en) 1981-08-19

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ID=6093638

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8103092A Withdrawn GB2069047A (en) 1980-02-02 1981-02-02 Electronically-controlled fuel injection system for an internal combustion engine

Country Status (5)

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JP (1) JPS56121830A (en)
DE (1) DE3003904A1 (en)
FR (1) FR2475134A1 (en)
GB (1) GB2069047A (en)
IT (1) IT1167703B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2636675A1 (en) * 1988-09-21 1990-03-23 Usui Kokusai Sangyo Kk FUEL INJECTOR, FUEL INJECTION DEVICE HAVING THE INJECTOR, AND DIESEL ENGINE EQUIPPED WITH SUCH A DEVICE
EP0740067A2 (en) * 1995-04-27 1996-10-30 Isuzu Motors Limited Accumulator-type fuel injection system

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH161397A (en) * 1932-01-06 1933-04-30 Schweiz Lokomotiv Und Maschine Liquid-controlled fuel valve for internal combustion engines.
US2191186A (en) * 1935-12-31 1940-02-20 Amery George Fuel injection system for internalcombustion engines
FR808907A (en) * 1936-07-10 1937-02-18 Fuel pump for internal combustion engines, complete with needle sprayers
GB1097752A (en) * 1963-09-09 1968-01-03 Ass Eng Ltd Fuel injection valves for internal combustion engines
CH443787A (en) * 1965-09-14 1967-09-15 Sulzer Ag Injection device of a piston internal combustion engine
CH443788A (en) * 1965-09-14 1967-09-15 Sulzer Ag Fuel injection device of a reciprocating internal combustion engine
DE1281207B (en) * 1966-01-28 1968-10-24 Maschf Augsburg Nuernberg Ag Fuel injection device for internal combustion engines
JPS5754619B2 (en) * 1973-08-28 1982-11-19
JPS592793B2 (en) * 1973-08-29 1984-01-20 株式会社ボッシュオートモーティブ システム Diesel engine repair service
DD113260A1 (en) * 1974-07-08 1975-05-20 Karl Marx Stadt Automobilbau
DE2529933C2 (en) * 1975-07-04 1984-07-19 M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8900 Augsburg Fuel injection device for internal combustion engines
US4080942A (en) * 1976-06-23 1978-03-28 The United States Of America As Represented By The Secretary Of The Army Metering fuel by compressibility
GB2016588B (en) * 1978-03-21 1982-08-11 Lucas Industries Ltd Fuel system for a multi-cylinder engine

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2636675A1 (en) * 1988-09-21 1990-03-23 Usui Kokusai Sangyo Kk FUEL INJECTOR, FUEL INJECTION DEVICE HAVING THE INJECTOR, AND DIESEL ENGINE EQUIPPED WITH SUCH A DEVICE
GB2223273A (en) * 1988-09-21 1990-04-04 Usui Kokusai Sangyo Kk Fuel injector control
EP0740067A2 (en) * 1995-04-27 1996-10-30 Isuzu Motors Limited Accumulator-type fuel injection system
EP0740067A3 (en) * 1995-04-27 1997-01-08 Isuzu Motors Ltd Accumulator-type fuel injection system
US5732679A (en) * 1995-04-27 1998-03-31 Isuzu Motors Limited Accumulator-type fuel injection system

Also Published As

Publication number Publication date
FR2475134A1 (en) 1981-08-07
IT8119435A0 (en) 1981-01-30
JPS56121830A (en) 1981-09-24
DE3003904A1 (en) 1981-08-06
FR2475134B3 (en) 1982-11-19
IT1167703B (en) 1987-05-13

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