EP0383959A1 - Dispositif de formation de mélange air-carburant pour moteurs à combustion interne - Google Patents

Dispositif de formation de mélange air-carburant pour moteurs à combustion interne Download PDF

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Publication number
EP0383959A1
EP0383959A1 EP89102665A EP89102665A EP0383959A1 EP 0383959 A1 EP0383959 A1 EP 0383959A1 EP 89102665 A EP89102665 A EP 89102665A EP 89102665 A EP89102665 A EP 89102665A EP 0383959 A1 EP0383959 A1 EP 0383959A1
Authority
EP
European Patent Office
Prior art keywords
fuel
nozzle
metering
delivery line
formation device
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.)
Ceased
Application number
EP89102665A
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German (de)
English (en)
Inventor
Martin Prof. Dr. Feldinger
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.)
Mannesmann VDO AG
Original Assignee
Mannesmann VDO 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 Mannesmann VDO AG filed Critical Mannesmann VDO AG
Publication of EP0383959A1 publication Critical patent/EP0383959A1/fr
Ceased 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
    • F02M9/00—Carburettors having air or fuel-air mixture passage throttling valves other than of butterfly type; Carburettors having fuel-air mixing chambers of variable shape or position
    • F02M9/12—Carburettors having air or fuel-air mixture passage throttling valves other than of butterfly type; Carburettors having fuel-air mixing chambers of variable shape or position having other specific means for controlling the passage, or for varying cross-sectional area, of fuel-air mixing chambers
    • F02M9/127—Axially movable throttle valves concentric with the axis of the mixture passage
    • F02M9/133—Axially movable throttle valves concentric with the axis of the mixture passage the throttle valves having mushroom-shaped bodies
    • 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
    • F02M7/00—Carburettors with means for influencing, e.g. enriching or keeping constant, fuel/air ratio of charge under varying conditions
    • F02M7/12—Other installations, with moving parts, for influencing fuel/air ratio, e.g. having valves
    • F02M7/22—Other installations, with moving parts, for influencing fuel/air ratio, e.g. having valves fuel flow cross-sectional area being controlled dependent on air-throttle-valve position

Definitions

  • the invention relates to a fuel-air mixture formation device for internal combustion engines, with a rotationally symmetrical nozzle body which, together with a rotationally symmetrical throttle body displaceable therein, forms a convergent-divergent nozzle which opens into an intake manifold of the internal combustion engine, and with a fuel quantity control device with a fuel line which opens into or near the narrowest cross section in the nozzle.
  • the fuel-air mixture is precontrolled by calling up specific data from a map determined by tests, in which, for example, the speeds and torques of the engine are recorded as a reference point and a linear interpolation is carried out between the individual reference points.
  • a pre-control via a map can only be an approximate solution because engine-independent variables are not included in the determination of the map, or only secondary.
  • a map control requires a delayed pilot control of the fuel-air mixture because of the necessary comparison of current engine data with the map data and only then does the control begin, so that the additional control via a lambda probe is of greater importance.
  • the object of the invention is to provide a fuel-air mixture formation device for internal combustion engines of the type mentioned, which enables simple and rapid pilot control of the composition of the fuel-air mixture.
  • a fuel-air mixture formation device for internal combustion engines of the type mentioned which is characterized in that the fuel quantity control device has a metering unit which is connected to a fuel delivery line connected to the fuel tank and the fuel delivery line opening into the nozzle, and a motor load-dependent Movable metering element for controlling the fuel flow rate comprises, which is coupled to the nozzle body in a movement-locking manner.
  • the invention is based on the finding that in the mixture formation device the flow velocity of the air reaches the speed of sound for a wide operating range of the engine. As long as the pressure of the air in the intake manifold of the engine falls below a "critical" value, nothing changes in the flow velocity and the condition of the air in the narrowest cross section of the nozzle. This means that the air mass flow remains constant when the throttle body is in an unchangeable position. If a constant fuel mass flow is supplied to this constant air mass flow, the composition of the resulting mixture (lambda value) also remains constant; the pilot control of the fuel-air mixture is unchangeable in this case.
  • the specific assignment of constant air mass flow and constant fuel mass flow is achieved according to the invention by the movement-locking coupling of the metering device and the body.
  • the basic prerequisites for uniform mixture pilot control is that the effective cross section of the fuel metering element is proportional to the effective cross section of the nozzle. If, starting from the "critical flow state" in the narrowest cross-section of the nozzle, the engine load is increased, the transition from critical flow (with "speed of sound”) to subcritical flow (“subsonic flow”) will finally take place when a certain air pressure in the intake manifold is exceeded. If the throttle body were left unchanged, the air mass flow drawn in by the engine would be smaller.
  • the motor-independent variables are preferably the pressure PL of the air in the narrowest cross section of the nozzle, the ambient pressure p o in front of the nozzle and the ambient temperature T o in front of the nozzle.
  • the regulation mentioned makes reference to the physical conditions according to which the air mass flow is a function of the ratio ⁇ of the specific heat, the gas constant R, the so-called Laval cross section A D as a function of the throttle body position YK , the ambient pressure p o , the ambient temperature T o and the Pressure pL of the air in the narrowest cross section of the nozzle (Laval cross section), and the fuel mass flow is a function ⁇ R, A ⁇ , the value X representing the stoichiometric combustion, the stoichiometric ratio air / fuel L min , p o , T o , PL .
  • a special embodiment of the fuel-air mixture formation device provides that the metering unit is divided into two partial spaces by an aperture having an opening, one of the partial spaces with the fuel delivery line connected to the fuel tank and the other of the partial spaces with the opening into the nozzle Fuel delivery line is connected and the metering element passes through the orifice more or less depending on its engine load-dependent position.
  • a particularly simple assignment of the movements of the metering element and throttle body results when these are rigidly connected to one another and, moreover, the metering element can be moved directly or indirectly by means of the vehicle accelerator pedal. A movement of the throttle body consequently leads to a proportional movement of the metering element with a proportional change in air mass flow and fuel mass flow.
  • both the throttle body and the metering element are designed as cones, which are connected in the same direction and rotationally symmetrically to a common bearing axis, whereby the term cone is also to be understood as meaning cone designs which are mathematically defined by a defined cone.
  • the subspace of the metering unit assigned to the fuel tank-side fuel delivery line is connected via an opening to a compensating chamber, a compensating element coupled to the metering element in a movement-locking manner, in particular a compensating piston, sealingly penetrating the opening and the compensating chamber via a branch line the nozzle-side fuel delivery line is connected.
  • This configuration of the metering unit serves to correct the mixture composition when the load condition of the engine changes. A change in the load condition (pressure in the intake manifold) of the engine would lead to a change in air pressure in the intake manifold.
  • the above-mentioned configuration of the metering unit with a compensation space largely compensates for the influence of the amount of fuel changing when the intake manifold pressure changes, in that when the intake manifold pressure is reduced, that is to say when fuel is evaporated from the intake manifold walls, the mixture supplied by the mixture formation device is emaciated by fuel instead of being fed to the nozzle into the equalization chamber, and with an increase in the intake manifold pressure, i.e. condensation of fuel from the mixture supplied by the mixture formation device and accumulation on the intake pipe walls, the mixture supplied by the mixture formation device is enriched by additional fuel from the Compensation room is promoted.
  • the fuel quantity is controlled by means of a metering regulator which can be controlled by control electronics which, as described above, corrects the coupling of the metering element and the nozzle body as a function of the motor-independent variables.
  • a further correction variable can be the air ratio, which can be determined in a known manner by means of a lambda probe and which is likewise input into the control electronics.
  • the metering controller advantageously has two fuel spaces which are sealed off from one another by means of a flexible membrane, and a fuel space is connected via a branch line to the fuel delivery line connected to the fuel tank and a return line to the fuel tank, and the inflow of fuel into this fuel space by way of the Control electronics adjustable throttle element and there is a static throttle element in the drain, the other fuel chamber is connected to the nozzle via a first part of the fuel delivery line opening into the nozzle and a second part of this fuel delivery line to the nozzle and the passage cross section of the other fuel chamber by means of the flexible membrane is adjustable.
  • the branch line should be adjacent to a flexible membrane end assigned to a fuel chamber and the passage cross section between the line mouth and the membrane should be variable by means of an electromagnet acting on the membrane and controllable via the control electronics.
  • the mixture formation device should have a system pressure regulator which ensures a constant fuel pressure in the fuel delivery line to the metering unit and in the branch line.
  • the metering unit 6 is divided into two sub-spaces 16 and 17 by an aperture 15 having an opening 14, the sub-space 16 with the fuel tank 1 via the fuel delivery line 5 and the sub-area 17 via the fuel delivery line 7 with the Nozzle 9 is connected.
  • a cone-shaped metering element 18 can be moved in the direction of its axis of rotation perpendicular to the diaphragm plane into and out of the diaphragm opening and thus determines the remaining passage cross section of the fuel through the metering unit 6 depending on its position.
  • the metering element 18 is rotationally symmetrical in the area of its tip and its circular base connected to an axis 19 and mounted in two bearings 20 of the metering unit 6 so as to be longitudinally displaceable.
  • the throttle body 11 is connected to the free end of the axis 19 in a rotationally symmetrical manner with respect to the metering element 18, so that the movements of the throttle body 11 and the metering element 18 are coupled because of the movement-locking connection.
  • the axial path of the axis 19 and thus the path of the throttle body 11 and metering element 18 correspond to the accelerator pedal path indicated by the double arrow A.
  • the metering regulator has, inter alia, two fuel spaces 22 and 23 sealed against one another by means of a flexible membrane 21.
  • the fuel chamber 22 is divided by a connecting line 24 into two subspaces 22a and 22b, a branch line 25 opening into the subspace 22b is connected behind the system pressure regulator 4 to the fuel delivery line 5, so that part of the fuel delivered by the pump 2 is connected via the branch line 25 is promoted in the fuel chamber 22.
  • a return line 26, which leads to tank 1, is connected to subspace 22a of fuel chamber 22.
  • a fixed throttle 27 is inserted into the return line 26 in the region of the outflow from the subspace 22a.
  • the branch line 25 is led into the partial space 22b and ends at a slight distance from the partial space wall opposite the entry area, which is also designed as a flexible membrane 28.
  • an electromagnet 29 is arranged, which can be controlled via control electronics 30 and, due to a design of the flexible diaphragm 28 which is responsive to a magnet, when a control current is applied, the diaphragm 28 more or less from the adjacent opening of the Branch line 25 moved away.
  • the input of the fuel chamber 22 is thus provided with a movable throttle and the output of this fuel chamber is provided with a fixed throttle 27.
  • the first section 7a of the fuel delivery line 7 opens into the fuel chamber 23 and, corresponding to the design of the branch line 25, the second section 7b of the fuel delivery line 7 extends into the fuel chamber 23 until just before the flexible membrane 21.
  • a movable throttle is thus likewise formed between this and the facing inflow opening of the second section 7b of the fuel delivery line 7, but the throttling results there due to the movable throttle assigned to the subspace 22b and the different pressures which thus arise in the subspace 22.
  • the current lambda value can be entered into the control electronics, which is determined in a known manner via a lambda probe.
  • FIG. 2 illustrates the relationships between the air mass flow m a and the fuel mass flow m s determined in the experiment as a function of the pressure Pl in the narrowest cross section of the nozzle 9 for the supercritical and subcritical flow state.
  • the fuel mass flow ⁇ B is reduced via the control electronics 30, into which the pressure PL and the pressure p o and the temperature T o are entered as an essential parameter.
  • the control variable originating from the control electronics 30 activates the electromagnet 29 which, according to the measure of the control variable, more or less attracts the flexible membrane 28 and thus increases the passage gap between the open end of the branch line 25 and the membrane 28 accordingly. This causes an increase in the fuel pressure in the fuel chamber 22, so that the flexible membrane 21 is moved onto the open end of the second section 7b of the fuel delivery line 7 and thus the gap between the flexible membrane and this section 7b is reduced, with the result that less Fuel can be delivered through the fuel delivery line 7.
  • Figure 3 shows that with a normalized representation m + of the air mass flow and the normalized fuel mass flow required for constant lambda value the scattering band for and becomes narrow for the entire operating range, that is to say for the pressure in the narrowest cross section of the nozzle, that is to say it is only slightly dependent on the position of the throttle body 11.
  • m + of the air mass flow and the normalized fuel mass flow required for constant lambda value the scattering band for and becomes narrow for the entire operating range, that is to say for the pressure in the narrowest cross section of the nozzle, that is to say it is only slightly dependent on the position of the throttle body 11.
  • For the subcritical flow area are supercritical because of m a ⁇ m a . and mB ⁇
  • Deviations due to the scattering range around the ideal lambda value can be compensated for by the lambda probe, which works together with the control electronics 30.
  • FIG. 4 shows the modified design of the metering unit 6.
  • the fuel delivery line 5 opens into the metering unit 6 on the side facing away from the fuel delivery line 7.
  • the sub-space 16 is connected via an opening 31 to a compensation chamber 32, a compensation piston 33 connected to the metering element 18 and arranged concentrically to its axis of rotation passes through the opening 31, and the compensation chamber 32 is also connected via a branch line 34 connected to the first section 7a of the nozzle-side fuel delivery line 7.
  • the configuration of the metering unit 6 shown in FIG. 4 makes it possible to largely compensate for the influence of the amount of fuel changing when the intake manifold pressure changes.
  • the mixture is thinned by the mixture formation device by moving the accelerator pedal in the sense of a reduction in the mixture quantity to a corresponding movement of the metering element 18 and the compensating piston 33 and the throttle body 11 in the direction the arrows drawn with solid lines takes place, which due to the increasing compensation space 32 a part of Fuel which is usually conveyed into the fuel delivery line 7b is stored in the compensation space 32 via the branch line 34.
  • the mixture supplied by the mixture formation device is enriched by the throttle body 11 and the metering element 18 with the compensating piston 33 are moved in the opposite direction according to the arrows drawn in dashed lines, so that fuel additionally flows into the section 7b of the fuel delivery line 7 via the branch line 34 as a result of the associated reduction in the compensating space 32.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
EP89102665A 1989-01-26 1989-02-16 Dispositif de formation de mélange air-carburant pour moteurs à combustion interne Ceased EP0383959A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3902283 1989-01-26
DE19893902283 DE3902283A1 (de) 1989-01-26 1989-01-26 Kraftstoff-luft-gemischbildungsvorrichtung fuer verbrennungsmotoren

Publications (1)

Publication Number Publication Date
EP0383959A1 true EP0383959A1 (fr) 1990-08-29

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Application Number Title Priority Date Filing Date
EP89102665A Ceased EP0383959A1 (fr) 1989-01-26 1989-02-16 Dispositif de formation de mélange air-carburant pour moteurs à combustion interne

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EP (1) EP0383959A1 (fr)
JP (1) JPH02207174A (fr)
DE (1) DE3902283A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2654389A (en) * 1947-02-12 1953-10-06 Carter Carburetor Corp Metering valve adjustment
US2964303A (en) * 1958-08-21 1960-12-13 Acf Ind Inc Carburetor metering adjustment
US4087493A (en) * 1975-02-13 1978-05-02 Carbo-Economy, S.A. Apparatus for providing a uniform combustible air-fuel mixture

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2245418C3 (de) * 1972-09-15 1979-06-28 Robert Bosch Gmbh, 7000 Stuttgart Kraftstoffzumeßanlage für Brennkraftmaschinen
BR7308306D0 (pt) * 1973-10-23 1975-06-03 S Louis Carburador a vacuo constante
US4206158A (en) * 1976-04-05 1980-06-03 Ford Motor Company Sonic flow carburetor with fuel distributing means
JPS54161033A (en) * 1978-06-09 1979-12-20 Nissin Electric Co Ltd Average power detection system
JPS5618045A (en) * 1979-07-24 1981-02-20 Ntn Toyo Bearing Co Ltd Fuel injection device
JPS5835265A (ja) * 1981-08-25 1983-03-01 Mitsubishi Electric Corp 混合気調量装置
DE3231937C2 (de) * 1982-08-27 1985-10-17 Atlas Fahrzeugtechnik GmbH, 5980 Werdohl Elektronisch gesteuerte Brennstoffdosiervorrichtung für einen Gleichdruckvergaser
DE3337261A1 (de) * 1983-10-13 1985-05-02 Atlas Fahrzeugtechnik GmbH, 5980 Werdohl Vergaser fuer einen ottomotor
US4670195A (en) * 1985-04-26 1987-06-02 Robson Richard E G Carburetor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2654389A (en) * 1947-02-12 1953-10-06 Carter Carburetor Corp Metering valve adjustment
US2964303A (en) * 1958-08-21 1960-12-13 Acf Ind Inc Carburetor metering adjustment
US4087493A (en) * 1975-02-13 1978-05-02 Carbo-Economy, S.A. Apparatus for providing a uniform combustible air-fuel mixture

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Publication number Publication date
JPH02207174A (ja) 1990-08-16
DE3902283A1 (de) 1990-08-02

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