EP0037279B1 - Analog-Vergaser - Google Patents

Analog-Vergaser Download PDF

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Publication number
EP0037279B1
EP0037279B1 EP81301380A EP81301380A EP0037279B1 EP 0037279 B1 EP0037279 B1 EP 0037279B1 EP 81301380 A EP81301380 A EP 81301380A EP 81301380 A EP81301380 A EP 81301380A EP 0037279 B1 EP0037279 B1 EP 0037279B1
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Prior art keywords
fuel
valve
pressure
air
flow
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EP81301380A
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English (en)
French (fr)
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EP0037279A1 (de
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Merle Robert Showalter
John M. Clark, Jr.
Wray J. Fogwell
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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
    • F02M69/00—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel
    • F02M69/16—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for metering continuous fuel flow to injectors or means for varying fuel pressure upstream of continuously or intermittently operated injectors
    • F02M69/18—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for metering continuous fuel flow to injectors or means for varying fuel pressure upstream of continuously or intermittently operated injectors the means being metering valves throttling fuel passages to injectors or by-pass valves throttling overflow passages, the metering valves being actuated by a device responsive to the engine working parameters, e.g. engine load, speed, temperature or quantity of air
    • F02M69/20—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by means for metering continuous fuel flow to injectors or means for varying fuel pressure upstream of continuously or intermittently operated injectors the means being metering valves throttling fuel passages to injectors or by-pass valves throttling overflow passages, the metering valves being actuated by a device responsive to the engine working parameters, e.g. engine load, speed, temperature or quantity of air the device being a servo-motor, e.g. using engine intake air pressure or vacuum
    • 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

  • any fuel-air metering device which is not a positive displacement device will have fuel governed by the incompressible flow equation (Bernoulli's equation) and will have the air flow governed by the compressible flow equation.
  • These equations are exact in the same physical sense that the basic equations of Newtonian physics are exact, and in the same sense that the tabulated thermodynamic functions (for instance, entropy, enthalpy, and internal energy) are exact functions.
  • the present invention fuel-air metering system involves only the compressible flow equation for air flows, the incompressible flow equation governing the fuel flow, and simple geometry. It is therefore a fundamentally simpler system than that involved with injection systems using solenoid valves, and also a much simpler system than conventional carburetors which have a multiplicity of interlocking air-fuel control systems which interact in complex and analytically intractable ways.
  • the inventors have considered a number of practical economic and structural issues.
  • the system is designed to be compatible with inexpensive low pressure diaphragm fuel pumps, although it is also compatible with higher fuel pressure systems.
  • Any system designed to meter to high accuracy must have parts built to a similarly high level of accuracy, but the inventors have taken pains to make sure that the parts of the system which must be made to close tolerances can be made so by simple manufacturing techniques.
  • issues of durability as well as dynamic response have been considered.
  • the present invention is adapted to easily connect with either conventional control via diaphragms or with electronic air/fuel ratio controls of one sort or another.
  • the interaction of the metering system with its control system is in each case analytically clear and straightforward.
  • the parts involved in the control system can be made with relatively large absolute dimensions, so that they can be made to high relative accuracies.
  • the present invention relates to a metering system of the said general type, but is characterised in that the air by-pass includes the upstream restrictor, a pressure recovery intermediate chamber from which the control pressure downstream of the upstream restrictor is tapped and a downstream restrictor, the effective flow orifice of upstream restrictor being large in relation to the effective flow orifice of downstream restrictor, air valve and fuel valve being shaped and arranged in such a way that the effective apertures of the two valves remain in substantially constant proportion to each other at all operating positions of said valves, whereby the airflow valve comprises a smoothly convergent upstream face and a cusp on the downstream side and the fuel flow valve comprises at least in its strongly retracting position a smoothly convergent passage on the upstream side and a sudden expansion on the downstream side and wherein the variable area fuel flow valve obeys the fuel flow relation where the coefficient of discharge C f is substantially constant over the Reynolds number range relevant for any set A, and where ⁇ P f is the fuel pressure differential across the valve at well defined pressure tap
  • Figures 1 and 2 show the air circuit and fuel circuit of the metering system in schematic form.
  • a throttle plate 1 pivots on shaft 12 in an air flow passage 3.
  • Throttle plate 1 is specially shaped with smoothly convergent surfaces and with a vortex stabilizing contour on the upwardly pivoted side.
  • This aerodynamic shaping of the throttle valve is required to achieve an air throttle having a coefficient of discharge at each opening position which is relatively insensitive to variations in Mach Number and Reynolds Number which occur due to variations in the pressure drop across the throttle.
  • This shaping is important: Conventional throttle plates exhibit variations in coefficient of discharge of as much as 30 percent, and this variation in coefficient of discharge is quite unacceptable in the current metering system.
  • a small fraction of the air flow past the carburetor passes through an air flow bypass system which generates a pressure differential used to control the fuel pressure differential across the fuel valve.
  • Intake air passes into opening 4 at approximately stagnation pressure with respect to throttle 1 and this flow is sucked past a fixed orifice 5 which discharges into a relatively open passage 6.
  • Air from passage 6 is sucked past fixed orifice 7 into passage 8.
  • Passage 8 is located in a position where it is in contact with a pressure which approximates the vena contracta static pressure downstream of throttle 1.
  • Orifice 7 is significantly smaller than orifice 5.
  • the pressure drop across orifice 5 is small, so that air flowing past orifice 5 acts as an approximately incompressible fluid, in good analogy with the incompressible liquid fuel.
  • Orifice 7 is designed to have a coefficient of discharge insensitive to Reynolds Number and Mach Number.
  • the air flow past orifice 7 varies in almost exact proportion to the air flow per unit area past air throttle 1.
  • the air flow past orifice 5 is exactly equal to the flow past orifice 7, and the pressure drop across orifice 5 varies to good approximation with the square of flow through orifice 5.
  • the pressure drop across orifice 5 is therefore a good signal for proportional control of fuel pressure drop across the fuel valve. Movement of needle 9 changes the effective flow area of orifice 5, and changing this flow area is a convenient way of changing the air fuel ratio supplied by the system.
  • Figure 2 shows the fuel control arrangement which includes a fuel valve opening in proportion to the air throttle opening and a negative feedback fuel pressure drop regulation system controlling pressure drop across this valve in proportion to the pressure drop across air orifice 5.
  • a fuel valve opening in proportion to the air throttle opening
  • a negative feedback fuel pressure drop regulation system controlling pressure drop across this valve in proportion to the pressure drop across air orifice 5.
  • slotted shaft plug valve 12a On the same shaft as throttle shaft 12 is slotted shaft plug valve 12a, which rotates within a receiving passage so as to have an effective flow area varying in precise proportion to the opening of air throttle 1.
  • this slotted shaft is on the throttle shaft, so that there is a zero lag and extremely positive linkage between fuel valve opening and air throttle opening.
  • Fuel air metering requires that the pressure drop across slotted shaft valve 12a vary in proportion to the pressure drop across orifice 5.
  • the pressure drop across fuel valve 12a is varied in proportion to the pressure differential across air flow orifice 5 by fuel pressure regulator assembly 13, 14, 15, 16.
  • a very low friction air piston 13 (which may have to be supported on hydrostatic bearings) is connected on its left face to a connecting passage 22 which connects to passage 6 at the pressure downstream of orifice 5.
  • On the right side of air piston 13 is the pressure upstream of orifice 5, which is communicated by connecting passage 20.
  • the pressure drop across orifice 5 therefore produces a leftward force on piston 13 equal to the area of piston 13 times the pressure drop across orifice 5.
  • This leftward force is transmitted by a thin cylindrical connecting rod 15 to fuel control piston valve 14 which rides in a cylinder on essentially frictionless hydrostatic gasoline bearings.
  • the fuel control valve piston 14 is connected on its left side to fuel pressure upstream of fuel valve 12a by passage 21, and on its right side is connected downstream of valve 12a by passage 16; the pressure differential across the fuel valve 12a generates a rightward force on piston 14 equal to this pressure drop times the area of piston 14.
  • the rightward force from piston 14 balances the leftward force from air piston 13; if the system is not in equilibrium, it will tend to move axially.
  • Axial motion of assembly 14, 15, 13 will rapidly change the pressure drop across piston 14, and this change will act to restore equilibrium.
  • Axial motion of piston 14 opens and closes fuel flow area to passage 16, and the orifice forced by piston 14 and passage 16 is the only orifice in series with fuel valve 12a. Passage 16 feeds fuel to the engine.
  • Assembly 14,15,13 acts as a servo controlled valve system controlling the pressure drop across the sleeve of piston 14 (the pressure difference between passage 11 and passage 16). Because passage 16 is the only outlet for fuel which flows past valve 12a, the axial position of piston 14 directly controls the pressure drop across valve 12a, and hence the fuel flow of the metering system. If assembly 13, 15, 14 doesn't stick, piston 14 will move to an axial position producing an exact force balance.
  • a force balance between fuel piston 14 and air piston 13 means that the fuel pressure drop across fuel valve 12a is proportional to the pressure drop across air orifice 5, which is what is required to produce a set air-fuel ratio from the analog carburetor.
  • the fuel flow control system of Figure 2 will work well if details are well handled and if the fuel pressure supplied to passage 10 is sufficient and smooth enough.
  • a fuel air metering system such as that shown on Figures 1 and 2 has operated successfully and with excellent accuracy on a test stand at Southwest Research Institute. The function of the system is rather simple and straightforwardly described with exact mathematics. Air flow past an air throttle 1 obeys to excellent approximation the standard compressible flow equation found in engineering textbooks.
  • the air flow throttle is positively linked with a fuel flow valve so that the fuel flow metering area is proportional to air throttle opening.
  • a two orifice in series air bypass system generates a flow signal closely proportional to the square of the mass flow per unit area past the throttle.
  • a negative feedback fuel regulator assembly controls fuel pressure drop across the fuel metering valve in proportion to the signal generated in this bypass system by regulating the flow resistance of an orifice in series with the fuel valve, thereby varying flow until pressure drop across the fuel control valve is in balance.
  • FIG. 3 shows solutions to these problems and has other advantages.
  • the air flow passages and fuel flow passages in the metering system of Figure 3 are very closely analogous to those of Figures 1 and 2.
  • the air flow passages analogous to Figure 1 are as follows: throttle 42 pivots in generally rectangular passage 40 and forms a variable area air throttle.
  • the coefficient of discharge of air throttle 42 has been shown experimentally to be very insensitive to Mach Number and Reynolds Number variations.
  • Flow from throttle 42 proceeds to downstream passage 44, and attaches in the form of a coanda wall attached stream to this wall.
  • Well upstream of throttle 42 is pick up passage 46, which is shown schematically (in a proper system pick up 46 would be in a large enough passage so that it was picking up air at upstream stagnation pressure).
  • Flow from pick up passage 46 moves through low flow resistance passage 45 and passes through orifice 48, which is analogous to orifice 5.
  • Downstream of orifice 48 is relatively large passage 49, which is large enough to dissipate the velocity of flow from orifice 48 and feed a relatively homogenous air flow to downstream orifice 50, which is analogous to orifice 7.
  • Orifice 50 feeds passage 51 which is connected to the wall of passage 44 on which the high speed flow from air throttle 42 is attached.
  • the dowrstream corner of the connection between passage 51 and air flow passage 44 is curved at 54, so flow from passage 51 merges smoothly with the main airflow and passage 51 contains a fluid at a pressure very close to the downstream vena contractá static pressure of air throttle 42.
  • Variation of the effective open area of orifice 48 as a function of engine intake manifold vacuum is obtained by diaphragm assembly 66, 68, 70, which moves needle 60, carried by diaphragm 58, in response to variations in the pressure of passage 56, which passage taps passage 51.
  • the diaphragm control for needle 60 achieves a controlled enrichment of the mixture at low intake manifold vacuums.
  • Diaphragm assembly 66, 68, 70 separates two chambers, chamber or large passage 49 is at the downstream pressure of orifice 48 and the other chamber 64 is at the upstream pressure of orifice 48.
  • the diaphragm assembly functions analogously to piston 13 in Figure 2.
  • Thin diaphragm 66 joins around its outside at peripheral connection 67 and is mounted on diaphragm cup 68.
  • Cup 68 is rigidly connected to circular rod 70 which rides in bushing 72 so that rod 70 and bushing 72 provide axial alignment of the diaphragm assembly.
  • the rightward side of the diaphragm assembly is at the pressure of chamber 64 which is connected through passage 47 to passage 45, approximately upstream throttle stagnation pressure.
  • Diaphragm assembly 66, 68 produces a leftward force on connecting rod 98 carried in bushing 99 to form part of a servo-controlled fuel valve assembly very analogous to the assembly 13 14, 15 of Figure 2.
  • the fuel flow circuit is analogous to Figure 2, and is partly shown schematically with details shown with respect to the fuel control servo valve arrangement.
  • Pressurized fuel in relatively large passage 84 is supplied by a pumping arrangement (not shown) and fuel from passage 84 passes convergently into rectangular passage 82 which is closed off by slotted plug valve 80, which is shown schematically on Figure 3 and is preferred to be on the same shaft as the air throttle 42, in a manner further shown in Figure 5.
  • Flow past slotted plug variable area valve 80 flows into a large expansion area 86, in a flow pattern characterized by Reynolds Number insensitivity and approximately complete dissipation downstream flow energy by turbulence, so that the pressure in passage 86 approximates the vena contracta static pressure directly downstream of plug valve 80.
  • Passage 86 is large and characterized by low fluid resistance. Passage 86 feeds passage 88, of similarly low resistance.
  • Large passage 88 flows from a relatively large area into a piston controlled servo valve area.
  • Piston 95 rides on cylinder sleeve 91.
  • ports 90 In sleeve 91 are symetrically located ports 90, which ports are arranged so that side forces on piston 95 due to pressure drops from the pressure of passage 88 to the pressure of passage ports 90 do not produce any net side forces tending to stick piston 95.
  • Piston 95 has a knife edged shape on its piston skirt, and axial motion of piston 95 in sleeve 91 moves the knife edged skirt opening and closing ports 90 so that the interaction of piston 95 with ports 90 forms a servo controlled valve.
  • Ports 90 feed an annular passage 92 around the outside of sleeve 91, and passage 92 feeds passage 110.
  • Passage 110 feeds fuel to the airstream (and hence to the engine) via a distribution port arrangement 111, 112 described further in Figure 7.
  • Static friction of piston 95 in cylinder sleeve 91 is further balanced by hydrostatic pressure balancing holes 93 symetrically spaced in sleeve 91, which holes serve to center piston 95 in the manner of a hydrostatic bearing.
  • Piston 95 opening and closing ports 90 is a servo controlled valve which operates in close analogy to piston 14 of Figure 2.
  • On the right side of piston 95 is a pressure very near to the downstream vena contracta static pressure downstream of variable area control valve 80. It has been found experimentally that with pistons 95 skirt knife edge as shown, the fluid motion near piston 95 has very small effects on the pressure on this side of the piston.
  • On the left side of piston 95 is chamber 100 which connects through a laminar filter 102 positioned in passage 101 and passage 103 with the pressure at pick-up port 104.
  • the laminar flow filter 102 (which can be conveniently formed of a conventional cigarette filter) functions well to damp any oscillation in servo-piston valve 95, since any axial motion of piston 95 requires that flow pass through this filter. It turns out that damping directly proportional to the axial velocity of piston 95 is precisely what is required for error free servo mechanism performance.
  • the laminar flow filter provides this damping and also serves to filter small particles which might otherwise cause piston 95 to stick in cylinder sleeve 91.
  • the function of the servo controlled valve assembly 91, 95, 98, 66, 68, 70 is substantially superior to that of the system shown in Figure 2.
  • the diaphragm arrangement has been shown to have essentially vanishing hysteresis and static friction. Engine vibration is sufficient to essentially eliminate static friction in connecting rod 98 and compensating rod 70.
  • the arrangement of ports 90 and 93 within sleeve 91 substantially eliminates the sticking of piston 95 within the cylinder sleeve 91 if these parts are carefully made.
  • the assembly forms an extremely accurate negative feedback servomechanism system, which is well damped by the laminar resistance of the cigarette filter in passage 101. This system has been shown to obey the equations which would be predicted in a free body diagram to an exceptional degree of exactness.
  • Air bag accumulator arrangement 115,116,118 is shown schematically to show how the two requirements can be satisfied at once.
  • Inside container 115 is relatively flexible air bag 116 which contains air under pressure.
  • mechanical grid 118 At the connection between air bag 116 and passage 84 is mechanical grid 118, which serves to constrain the expansion of bag 116 toward passage 84.
  • Figure 3 also shows a simple and effective evaporative emission control, which closes off flow to passage 110 when the engine stops and fuel pressure in passage 84 drops.
  • the system is intended to be used with a fuel pump arranged to leak down pressure when the engine stops. Such a pump is not shown, although many such pumps will occur to those skilled in the art.
  • a plug carrier 120 coaxial with piston 95 carries spring-piston arrangement 124, 122, with piston 122 slidably carried within the cylindrical passage 120 and sealed with a relatively low friction O-ring seal 130. Piston 122 is pushed rightward by spring 124.
  • Port 126 and thence the passage containing spring 124 is connected to an engine manifold pressure (connection not shown).
  • engine manifold pressure connection not shown.
  • the pressure force in chamber 100 forces piston 122 leftward to the position shown.
  • pressure in chamber 100 drops and spring 124 pushes piston 122 rightward, until piston 122 contacts piston 95 and pushes piston 95 to a position which fully closes ports 90 as well as ports 93. After this point fuel leakage from the system is negligible. The system therefore controls evaporative emissions.
  • the operation of the servo controlled valve depends for its accuracy on a very low friction, low hysteresis and low spring constant characteristic of the diaphragm 66.
  • a diaphragm shape we derived analytically has been tested experimentally and has the exceptionally low stiffness characteristics required (stiffness and hysteresis values more than a factor of 10 less than those characteristic of conventional diaphragms).
  • the shape of diaphragm 66 in Figure 3 is the shape of this diaphragm when the diaphragm is undeformed (when the pressure drop across the diaphragm is negligibly small).
  • the shape of the diaphragm is significantly different from conventional diaphragm shapes, and points in the diaphragm are shifted outward radially compared to the geometric shapes which are typical of the prior art. For example, consider point 129 on diaphragm 66. When the pressure drop across diaphragm 66 becomes significant, pressure forces will serve to change the shape of the diaphragm so that point 129 shifts radially inward. Virtually all other points on the diaphragm will similarly move inward radially.
  • diaphragm stiffness occurs because of circumferential stretching which occurs as the diaphragm moves axially, and the buckled form of the diaphragm shape 66 totally eliminates these circumferential stress terms, and in consequence, produces a diaphragm which is an order of magnitude less stiff than that of prior art diaphragms.
  • the diaphragm shaping of 66 is useful, since it permits diaphragms to be used in devices of much higher precision than has heretofore been possible.
  • diaphragm 66 The resistance of diaphragm 66 to axial motion within the control range relevant to the servo control valve motion of piston 95 is essentially negligible, so that the diaphragm serves as an effectively zero friction piston which produces a force ideally suited for controlling servo valve piston 95.
  • throttle 42 The detailed shape of throttle 42 is important. First it can be clearly seen that the open area of throttle 42 varies as the angle ⁇ increases according to the formula It should be clear that the projected open area of plug valve 80 with respect to its generally rectangular passage should be a quite similar equation
  • the K. can be the same for both the fuel valve and the air valve, in which case the projected open area of both valves will vary in exact proportion.
  • the air projected open area varies according to essentially the same relation, so that for both sorts of throttle valves a close proportioning between fuel flow valve area and air flow valve area is possible with a system which puts both valves on the same shaft.
  • throttle 42 the shape of throttle 42 is arranged specifically so that it is very insensitive in its coefficient of discharge to variations in Mach Number and Reynolds Number which occur across it due to variations in the intake manifold vacuum of the system engine downstream passage 44.
  • a smoothly convergent curve 142 which constrains the convergent streamlines upstream of the throttle valve, tending to stabilize the coefficient of discharge of the throttle.
  • cusp 143 On the downstream side of the throttle 42 is cusp 143, which is arranged to stabilize a parasitic vortex driven by the high speed stream past the throttle. This vortex smoothly merges with this high speed stream and tends strongly to stabilize the shape of the vena contracta downstream of the throttle plate independently of Mach Number.
  • a throttle plate like throttle 42 is essentially Mach Number and Reynolds Number insensitive for all the manifold vacuums which occur at each angle of throttle opening.
  • maximum Mach Numbers may not be higher than .3, while the Mach Number range past the throttle plate will vary from Mach 1 to perhaps Mach .2 when the throttle is more nearly closed.
  • Shaping the air throttle for Mach and Reynolds Number insensitivity is important for the practical performance of the present invention metering system.
  • the variation of coefficient of discharge with Mach Number is around 30 percent and this variation entails an unacceptable 30 percent variation in air fuel ratio from the metering system.
  • Figure 3 also shows an extremely inexpensive and exactly analytic system for enriching the mixture under conditions of very low manifold vacuum operation.
  • Connecting Rod 98 has one end at the pressure of passage 88, and the other end at the typically much lower pressure of chamber 49, so that a rightward error force is produced by rod 98 equal to the cross sectional area of rod 98 times the pressure difference between passages 88 and 49.
  • connecting rod 70 is also at the pressure of passage 88, since it communicates with passage 88 through passage 87. There is therefore a leftward force on connecting rod 70 equal to the cross sectional area of rod 70 times the pressure difference between passage 88 and chamber 64.
  • the pressure differential between chamber 49 and and chamber 64 is typically much smaller than the pressure differential between either chamber and passage 88.
  • FIG. 3 shows as many details of the present invention metering system as can be readily placed in one drawing. There are details which, because of graphics, were not shown.
  • the pickup of upstream air at 46 and the passages feeding the air orifice 48 are too small, and the pickup at 46 will not pick up air at true upstream stagnation pressure. This imposes an error, but one skilled in fluid mechanics can readily design an pickup analogous to 46 which does read approximately stagnation pressure upstream of the throttle plate.
  • a pickup in the air cleaner passage (not shown) will read an excellent approximation of upstream stagnation pressure. In this case as in all others the difference between stagnation and static pressure becomes insignificant as velocities become very small.
  • Figure 4 shows a two orifice in series flow system which corresponds closely to that in a metering system developed by the inventors, and particularly shows orifice shapes having coefficients of discharge which are insensitive to either Reynolds Number or Mach Number change in the operating range of the system.
  • Block 145 is provided with chamber 146, which has a very large cross sectional area with respect to orifice 148, which corresponds to orifice 48 in Figure 3 and orifice 5 in Figure 1.
  • a control needle 160 partly blocks off the cross sectional area of orifice 148. Flow past orifice 148 flows into chamber 149, and it can be seen that the cross section directly downstream of orifice 148 expands very suddenly so as to essentially eliminate pressure recovery of the flow downstream orifice 148.
  • orifice 148 The smoothly convergent shape of orifice 148, with its large upstream passage and sudden expansion downstream produces an orifice which has a coefficient of discharge which is extremely constant so that the mass flow past orifice 148 obeys its theoretical flow equation to excellent accuracy.
  • Orifice 148 is insensitive to Reynolds Number because the shape of orifice 148 constrains the flow streamlines in a pattern which is essentially invariant over the range of pressure drops relevant to orifice 148.
  • the flow pattern downstream of orifice 148 is also effectively uniform over the range of flows relevant to the orifice.
  • Chamber 149 is analogous to chamber 49 in Figure 3 and passage 6 in Figure 1. Chamber 149 is sufficiently large and sufficiently open so that the flow condition of the flow in the chamber as it approaches downstream orifice 150 is quite uniform.
  • Orifice 150 is analogous to orifice 7 in Figure 1, and connects chamber 149 with chamber 151, which chamber is connected so that it is at the static downstream pressure directly downstream of the air throttle.
  • the curvature of orifice 150 is also such as to produce an extremely constant coefficient of discharge, and the cross sectional area of orifice 150 is controlled with control needle 152.
  • Axial motion of either needle 160 or 152 will change the air fuel ratio of a metering system connected to the flow block of Figure 4. It should be noted with respect to orifice 150 that the upstream flow is open and cleanly converging, and the flow from orifice 150 flows into a very expanded cross sectional area of chamber 151.
  • Orifice 150 is designed to have a coefficient of discharge of nearly one, which means that the minimum cross sectional area of the flow streamlines occurs quite near the outlet plane of orifice 150 rather than farther downstream. Orifices with coefficients of discharge nearly one and no divergent sections are automatically insensitive to Mach Number, since compressibility effects cannot change the shape of their flow streamlines.
  • the shape of orifice 150 should be carefully coordinated with the relatively narrow taper angle of needle 152 to assure that, for the range of needle axial position relevant to the system, the orifice 150 is always a convergent orifice, and never becomes a convergent divergent passage because of the interaction of the areas of the needle 152 and orifice 150.
  • a rectangularly slotted shaft 161, carrying a seal 168 rides in a closely fitted receiver sleeve 162 having generally rectangular flow passages in it, and slotted shaft 161 is one part of the throttle shaft which also actuates the air throttle shown in phantom lines as 172.
  • the flow in the fuel valve is from left to right, and surface 164 forms a smoothly convergent passage shape which will be characterized by exceptionally thin boundary layers because of the rapid change in static pressure of the flow streamlines as they flow towards the gap between plug slot 160 and bottom surface 166 of sleeve 162.
  • the trigonometric relation of the opening gap area to twist angle ⁇ is exactly proportional to the relation of the gap between throttle 172 and air passage surface 174 shown in phantom lines, and it is easy to arrange things so that the projected flow area of both valves varies in exact proportion.
  • the shape of air throttle 172 is such that the coefficient of discharge of air throttle 172 is extremely insensitive to variations in Mach Number and Reynolds Number across this throttle. It is required that the coefficient of discharge as a function of shaft angle of the valve formed by slotted shaft 161 and receiver sleeve 162 also be characterized by an insensitivity of coefficient of discharge to variations in pressure drop (and hence Reynolds Number) across this valve. Because the fuel flow valve handles an incompressible fluid, Mach Number is not relevant, but Reynolds Number insensitivity matters.
  • Figure 5A is a view from the inlet passage.
  • Fuel from a relatively large inlet passage 179 flows into the generally rectangular passage of sleeve 162 through rounding entrance curvature 176, and flows through the rectangular passage until it contacts convergent surface 164, passing through the gap between surface 166 and 164 which forms the projected flow area of the valve.
  • a number of issues illustrated in Figure 5A are important. First of all, the relatively large area of the passage 179 is important.
  • valve When the valve is in relatively open condition, it behaves as two orifices in series, the first being the fixed orifice formed by curved surfaces 176 and the second being the orifice formed for the gap between surface 166 and the end point of surface 164 on slotted shaft 161.
  • curvature of curved surface 176 it is therefore possible to change the coefficient of discharge (and therefore the effective flow area) of the valve of Figure 5 as a function of shaft rotation. This must be done empirically, but it is relatively convenient to shape the rounded surfaces of 176 in such a way that the coefficient of discharge of the fuel valve and the air throttle match closely at all values of shaft angle.
  • Reynolds Number insensitivity of the fuel valve also requires that the flow conditions downstream of the valve be properly controlled.
  • Figures 5B in combination with Figure 5 shows how this can be done conveniently.
  • slotted shaft 161 rotates counterclockwise in Figure 5 the fuel valve opens and there is a gap between surface 166 and surface 164 through which fuel passes.
  • the high velocity fuel through this gap rushes downstream, and it is desirable to dissipate the velocity of this flow into turbulence with minimum pressure recovery if the fuel valve is to show optimal Reynolds Number insensitivity.
  • Reynolds Number insensitivity, and minimum pressure recovery are achieved by the most sudden convenient expansion of the fuel in the downstream section, and by arranging flow patterns to prevent wall attached streams from forming.
  • Coanda wall attached streams should be avoided since such attached streams are conducive to larger values of pressure recovery than otherwise occur downstream of the fuel valve.
  • Downstream of surface 166 is cutaway surface 170 which assures that the high velocity flow stream cannot attach to the lower wall of the downstream passage.
  • the high velocity jet from the fuel valve expands rapidly, and the passage from the rectangular passage 184 to open passage 186 is also an abrupt opening conducive to small or zero pressure recovery.
  • Figures 5, 5A and 5B show a fuel valve with a projected open area which varies in precise proportion with the projected open area of the air throttle valve, the fuel valve is built for an extremely constant coefficient of discharge over the range of Reynolds Numbers across which it must operate, and the shaping of curvatures 176 in the valve permits the coefficient of discharge of the fuel valve in relation to the air valve to be programmed as any desirable function of shaft angle 8.
  • FIG. 3 and 5 side views of Mach Number insensitive rectangular air throttle have been shown.
  • Figure 6 shows a view of the downstream side of the throttle plate of Figure 3, showing a notched section for the idle air flow of the system.
  • Throttle 42 is adapted to pivot on a shaft fitting through hole 192, shown in dashed lines. As the throttle pivots open, the open area between edge 194 and the left side of the rectangular passage in which the air throttle pivots opens for air flow. When the throttle is fully closed, there is still need for a minimum idle air flow and this idle flow passes through notch 195, which is adapted to produce a stable wall attached stream airflow downstream of the notch. This high speed stream is useful for downstream mixing purposes.
  • Figure 7 is a view of the fuel input passage shown at 111 and 112 of Figure 3, showing how the axial distribution of fuel into the high speed air stream past the air throttle is achieved, and how this distribution varies as the throttle shaft rotates. It is well to look first at Figure 3 to see the fuel introduction ports at 111 and the passage 112, both in the vicinity of the opening edge of air throttle 42. Figure 7 shows an axial cut-away of this passage.
  • the passage is characterised by a multiplicity of holes, 111, 200, 201, 202, 203, 204 and 205. When the throttle is fully closed and only the idle flow is passing, only hole 111 is open, and fuel from metering passage 110, shown in Figure 3, feeds directly to hole 111.
  • the throttle As the throttle rotates to open position, (depicted diagrammatically by dashed lines 195, 194 in Figure 7) the throttle first uncovers hole 200 then hole 201 then hole 202 then hole 203 then 204 and finally 205, so that after the throttle is part way open fuel is being distributed evenly along the axial length of throttle 42, for even introduction to the downstream passage 40 and to the engine.
  • This smooth axial distribution of fuel into the air stream is convenient for mixing arrangements downstream of air throttle 42.
  • Figure 8 is analogous to Figure 4, but shows an upstream orifice arrangement designed to produce 50 percent pressure recovery downstream of the upstream orifice.
  • chamber 245 is linked by passage 280 with the upstream pressure side 282 of a diaphragm assembly 270 used in the metering system control assembly, and the pressure in chamber 245 is approximately stagnation pressure upstream of the air throttle. Flow from chamber 245 passes through smoothly convergent nozzle 248, where the flow passes into cylindrical passage 253.
  • the ratio of orifice minimum cross sectional diameter to the diameter of cylindrical passage 253 is equal to .62, which is a value taken from Fluid Meters, sixth edition, 1971, the American Society of Mechanical Engineers, New York, New York, Page 221, the value being chosen to produce 50 percent pressure recovery.
  • nozzle 248 Directly downstream of nozzle 248 is pressure tap 246; which connects to the low stream pressure side 284 of the diaphragm, shown schematically as assembly 270.
  • Flow from cylindrical passage 253 proceeds to open chamber 249, which feeds downstream orifice 250.
  • Flow past orifice 250 expands to passage 251, which is strictly analogous to chamber 151 in Figure 4, and passage 251 is at the vena contracta static pressure downstream of the air throttle.
  • Figure 9 shows the most important compressible flow relations, plotting particularly the mass flow per unit area versus the mass flow per unit area which would occur at sonic velocity as a function of pressure drop across a perfect orifice.
  • the flow relations in Figure 9 are exact, and are used with precision in the two orifice in series passage and for the flow characteristics past the air throttle valve.
  • Figure 9 is copied from Page 197 of The Internal Combustion Engine in Theory and Practice, Volume 2, by Charles Fayette Taylor, MIT Press, copyright 1968.
  • the horizontal axis of Figure 9 is plotted in terms of two inversely related variables, the first being % ⁇ P across the orifice, and the second being the pressure ratio across the orifice.
  • the vertical axis plots two important functions, the first shows the ratio of mass flow to mass flow at sonic velocity which happens at various pressure drops. It is notable that 50 percent of the mass flow which would occur at sonic velocity already occurs at a pressure drop of 6 percent.
  • the compressibility function ⁇ 1>2' Reference to Figure 9 may be useful on a number of occasions when considering the mathematical analysis of the metering system, and evaluating its precision.
  • the objective of a fuel-air metering system is to control air/fuel ratios as a function of engine control variables.
  • Equation 5 hen
  • both A a C a and A f C vary with rotation angle 8 of a shaft
  • Equation 8 Both sides of Equation 8 are proportional to the massflow of air per unit of effective air flow orifice area.
  • Equation @ says that to get a constant air/fuel ratio from a metering system having a constant ratio of effective orifice areas between its fuel metering orifice and its air metering orifice, it is both necessary and sufficient that the pressure drop across the fuel metering orifice, ⁇ P f , be regulated in proportion to the square of the massflow per unit effective area past the airflow orifice.
  • Equation @ should look familiar to anyone who knows carburetors, since a venturi metering system has the suction of fuel into the airstream, ⁇ P fv , proportional to the square of massflow of air M av divided by ⁇ 2 , with ⁇ 2 a slowly moving function if the air venturi is large in relation to the air throttle opening.
  • both A av C av and A fv C fv are fixed, so that are in constant ratio, in analogy with the requirements of equation .
  • the present invention metering approach has the airflow metering orifice and the fuel flow metering orifice each varying as engine load is varied, with the ratio held constant.
  • Fuel-air metering systems for automobiles operate over a 30:1 to 50:1 range of massflows. For a venturi this involves ⁇ P fv ranges between 900:1 and 2500:1. Accurate fuel metering over this vast pressure range is never practical, so the carburetor requires separate idle systems, transition systems, and full power systems, and there are metering problems as these systems turn on or off.
  • the pressure range required for fuel metering is much less, by the ratio
  • This smaller range is a much more practical range of ⁇ P f to build hardware for, and it is therefore possible to build a metering system which involves only one basic fuel metering circuit to handle the entire flow range of engine requirements.
  • the present invention also has the practical advantage that ⁇ P f varies roughly with intake manifold vacuum, and so is conveniently large under the low load conditions where auto engines operate most of the time. For a venturi system, ⁇ P fv , is very small under these same low load conditions, making precise fuel-air metering at low loads very difficult with a carburetor.
  • ⁇ P f the pressure drop across the variable fuel valve, ⁇ P f , must be varied in proportion to the square of the massflow of air per unit effective open area past the air throttle valve. In the present invention this is done by producing a signal which varies in proportion to [( ⁇ 2 ⁇ ) ⁇ P a ] 2 with a specially designed two orifice in series bypass system, and controlling ⁇ P f in exact proportion to that signal with a regulator arrangement.
  • This regulator system will require some detailed discussion, but at this point assume a regulator is available such that ⁇ P f varies in exact proportion to pressure drop across an air diaphragm
  • the diaphragm can have one side connected to a chamber located between the two orifices, with the downstream orifice O d connecting the chamber to static pressure downstream the air throttle and the upstream orifice O " connecting the chamber with the stagnation pressure upstream of the air throttle valve. On the other side of the diaphragm is the stagnation pressure upstream of the air throttle. With this arrangement, the pressure drop across the diaphragm is equal to the pressure drop across the upstream orifice O u ,
  • Orifices O " and O d are in series, and therefore, instantaneous massflow rates past the two orifices must match at equilibrium:
  • Equation @ Satisfaction of Equation @ satisfies the requirements for the required constant air/fuel ratio.
  • the two orifice in series analogy is a very good one, and the departure of the analogy from perfection can be calculated exactly (assuming that the pressure downstream of O d and the pressure upstream of O u exactly correspond to the upstream stagnation and downstream static pressures of the air flow throttle valve, a matter which will be dealt with later).
  • M Od is exactly proportional to r o u max so a x% pressure drop in 0 u produces an x% reduction in M Od under choked (sonic flow) conditions.
  • This condition @ can be satisfied by controlling the shape of convergent surfaces 17b shown in Figures 5 and 5A. This shaping is straightforward, and must be done empirically for each metering system design.
  • air/fuel ratio varies exactly in proportion to n when ⁇ P od and ⁇ P a are small (the condition which occurs at relatively wide open throttle operating conditions).
  • M f is exactly proportional to 1/n, which shows that for the low ⁇ P od case is exactly proportional to n.
  • air/fuel ratio varies directly with the effective area of orifice O u , A ou C ou , and varies approximately inversely with the effective area of O d A Od Cod. Control of therefore, can be achieved by varying A ou C ou , by varying A Od C od , or by varying both in combination.
  • Orifices O d and O u can be built conveniently large, (with O d large enough to pass as much as 1 ⁇ 4 of the engine idle flow).
  • the large size of these orifices permits A ou C ou and A od C od to be controlled to an accuracy uncommon in fuel-air metering systems. Modulation of A Od C Od or A ou C ou can be done with large shaped needles, which are also conducive to high accuracy.
  • either orifice O u or O d could be replaced by two or more orifices in parallel, for instance
  • This 1/e value can readily be held to something like five milliseconds, which is very fast for a metering system.
  • the equilibration time of the servo controlled fuel valve for example, the time for axial adjustment of piston rod 95 in Figure 3, is not so fast as adjustment in the air bypass system itself, but can be made extremely fast.
  • the rate at which the fuel servo equilibrates is mostly determined by the laminar damping coefficient of cigarette filter 102, which can be readily controlled.
  • This equilibration time can be tested with an arrangement which puts a quick pulse of fuel into a passage such as 86 of Figure 3, and which then monitors the time for equilibrium with a piezo electric crystal.
  • the system 1/e can readily be held below 30 milliseconds and therefore the dynamic response to the current metering system can be exceptionally fast. It is worth noting that with orifice sizes corresponding to diaphragm fuel pump pressures the dynamic errors in the metering system during an acceleration are errors from the rich side (which is the safe side) so that nothing analogous to an accelerator pump is required by the function of the metering system curve per se.

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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)
  • Control Of The Air-Fuel Ratio Of Carburetors (AREA)

Claims (19)

1. Luft/Brennstoff-Dosiersystem für eine Brennkraftmaschine, mit einem Luftströmungsventil mit variablem Bereich in einer Strömungspassage (3) und einem Brennstoffströmungsventil variablen Bereichs (12a) in einer Brennstoffströmungspassage (10, 11), einem beweglichen Element (12) des Luftströmungsventils (1), das mit einem beweglichen Element des Brennstoffströmungsventils (12a) verbunden ist, wobei der Brennstoffdruckabfall am Brennstoffströmungsventil (12a) mittels eines zusätzlichen Ventils (14) in der Brennstoffströmungspassage regelbar ist, indem das zusätzliche Ventil (15) durch Kräfte gesteuert wird, die sich aus der Druckdifferenz des Brennstoffdruckes unmittelbar stromauf und stromab des Brennstoffströmungsventils (12a) und der Druckdifferenz des Luftduckes unmittelbar stromauf und stromab einer stromauf liegenden Verengung (5) in einer Bypass-Leitung von einer Stelle in der Luftströmungspassage (3) stromauf des Luftströmungsventils (1) bis zu einer Stelle stromab des Luftströmungsventils (1) ableiten, wobei die Luftdruckdifferenz mittels eines Luftdruckbalancesystems auf das zusätzliche Ventil (14) wirkt, dadurch gekennzeichnet, daß der Luftbypass umfaßt: die stromauf liegende Verengung (5), eine Druckwiedergewinnungszwischenkammer (6), von der der Steuerdruck stromab der stromauf liegenden Verengung (5) angezapft wird, und eine stromab liegende Verengung (7), daß die wirksame Strömungsöffnung der stromauf liegenden Verengung (5) im Verhältnis zur wirksamen Strömungsöffnung der stromab liegenden Verengung (7) groß ist, daß das Luftventil (1) und das Brennstoffventil (12a) so ausgebildet und angeordnet sind, daß die wirksamen Durchtrittsöffnungen der beiden Ventile in allen Betriebsstellungen der Ventile im wesentlichen in einem konstanten Verhältnis zueinander bleiben, wodurch das Luftströmungsventil (1) eine glatt konvergierende stromauf liegende Fläche und an der stromab liegenden Seite eine Krümmungsspitze aufweist, daß das Brennstoffströmungsventil (12a) zumindest in seiner stark zurückziehenden Stellung an der stromauf liegenden Seite eine glatt konvergierende Passage und an der stromab liegenden Seite eine plötzliche Expansion aufweist, wobei das Brennstoffströmungsventil mit variablem Bereich (12a) das Brennstoffströmungsverhältnis
Figure imgb0126
 erfüllt, worin der Abgabekoeffizient Cf im wesentlichen über den Reynolds-Zahlenbereich, der für jeden Satz Af relevant ist, konstant ist und worin ΔPf, ist der Brennstoffdruck, welcher am Ventil an wohldefinierten Druckanzapfstellen unterschiedlich ist, und worin das Luftströmungsventil mit variablem Bereich (1) das folgende Luftströmungsverhättnis erfüllt:
Figure imgb0127
worin Af=g (Ao) in einem exakten mathematischen Verhältnis und worin Af und Aa in grobem Verhältnis sich ändern, wobei das Luftventil (1) so ausgebildet ist, daß Ca über den Betriebsbereich des Ventils wirksam und veränderlich ist, worin ΔPa der Unterschied zwischen dem aufstromseitigen Stagnationsdruck und dem stromabseitigen vena contracta-statischen Druck ist, und worin die Mittel zum Regulieren des Druckabfalls am Brennstoffströmungsventil (12a) proportional zum Druckabfall an der stromaufliegenden Verengung (5) eine der folgenden Gleichungen erfüllen:
Figure imgb0128
oder
Figure imgb0129
Brennstoff stromab und worin APou das ΔP an der stromauf liegenden Verengung (5) ist, daß jede Verengung (5, 7) des Bypasses das folgende Luftströmungsverhältnis erfüllt
Figure imgb0130
und gilt:
Figure imgb0131
so daß APou proportional zu
Figure imgb0132
ist, so daß
Figure imgb0133
auf ein konstantes Verhältnis eingeregelt wird.
2. Dosiersystem nach Anspruch 1, dadurch gekennzeichnet, daß das zusätzliche Ventil ein Kolbenventil (14) in einer zylindrischen Brennstoffkammer ist, welche mit einer Passage (21) versehen ist, damit der Brennstoff von der stromauf liegenden Seite des Brennstoffventils (12a) zu einem Ende des Kolbenventils fließen kann, wobei eine zweite Passage (11) strömungsmittelmäßig die stromab liegende Seite des Brennstoffventils (12a) mit dem anderen Ende des Kolbens (14) verbindet.
3. Dosiersystem nach Anspruch 2, dadurch gekennzeichnet, daß die Brennstoffabgabepassage (16) oder (110) senkrecht zur Achse der zylindrischen Brennstoffkammer liegt.
4. Dosiersystem nach Anspruch 3, dadurch gekennzeichnet, daß eine Vielzahl von Brennstoffabgabepassagen (90, 93) radial und symmetrisch um die Zylinderwand beabstandet vorgesehen sind, um im wesentlichen die Seitenkräfte erzeugende statische Reibung zu eliminieren.
5. Dosiersystem nach Anspruch 2, dadurch gekennzeichnet, daß das Kolbenventil (95) durch eine Stange (98) mit dem Luftdruckbalancesystem (66, 68) verbunden ist, wodurch der Druckunterschied zwischen dem Brennstoffdruck und dem Luftdruck eine unerwünschte Kraft erzeugt, und wobei eine Kompensationsstange (70) mit der anderen Seite des Luftdruckbalancesystems verbunden ist und in Druckverbindung mit der Brennstoffströmungspassage (86, 88) stromab des Brennstoffströmungsventils (80) steht, um dieser unerwünschten Kraft entgegenzuwirken.
6. Dosiersystem nach Anspruch 1, dadurch gekennzeichnet, daß das Luftströmungsventil (12) oder (42) und das Brennstoffströmungsventil (12a) oder (80) auf derselben Welle angeordnet sind.
7. Dosiersystem nach Anspruch 1, dadurch gekennzeichnet, daß das Verhältnis der Luftmasse hinsichtlich der Brennstoffmasse geändert werden kann in Übereinstimmung mit den Motorsteuerungsvariablen durch Änderung des Verhältnisses der Bereiche der beiden in Reihe angeordneten Verengungen des Bypasses, indem entweder der wirksame Strömungsquerschnitt der stromauf liegenden Verengung (148) und/oder der wirksame Strömungsquerschnitt der stromab liegenden Verengung (150) geändert wird.
8. Dosiersystem nach Anspruch 1, dadurch gekennzeichnet, daß die Verengungen (48, 50) oder (148, 150) des Bypasses beide im wesentlichen unempfindlich gegenüber Änderungen der Reynold'schen Zahl und der Mach-Zahl sind.
9. Dosiersystem nach Anspruch 2 oder 3, dadurch gekennzeichnet, daß die Passage (84) für die Brennstoffversorgung stromauf des Brennstoffströmungsventils (80) mit einer Brennstoffpassage (103) versehen ist, die mit dem genannten einen Ende des Kolbenventils (95) verbunden ist, und daß die genannte Brennstoffpassage (103) mit einem Strömungsmittel-Strömungswiderstand (102) versehen ist, um die Oszillation des Kolbenventils (95) zu dämpfen.
10. Dosiersystem nach Anspruch 9, dadurch gekennzeichnet, daß der Strömungswiderstand (102) ein laminarer Strömungswiderstand ist.
11. Dosiersystem nach Anspruch 9, dadurch gekennzeichnet, daß die Brennstoffversorgungsmittel einen Akkumulator (115, 116, 118) für Dämpfungszwecke umfassen.
12. Dosiersystem nach Anspruch 6, dadurch gekennzeichnet, daß jedes Ventil (12, 12a) oder (42, 80) oder (172, 160) einen geometrisch projizierten Bereich haben, welcher der Gleichung
Figure imgb0134
worin
Figure imgb0135
Φ ein bestimmter Wellenwinkel ist.
13. Dosiersystem nach Anspruch 5, dadurch gekennzeichnet, daß der Durchmesser der Kompensationsstange (70) größer ist als der Durchmesser der Kolbenventil-Verbindungsstange (98), so daß die unerwünschte Kraft durch die Kraft der Kompensationsstange überbalanciert ist, wobei das Kolbenventil (95) hinsichtlich einer Anreicherung des Brennstoff-Luft-Gemisches bei niedrigen Werten von ΔPa wirkt.
14. Dosiersystem nach Anspruch 11, dadurch gekennzeichnet, daß der Akkumulator (115, 116, 118) nicht Brennstoffvolumen unter einem eingestellten minimalen Brennstoffdruck, und Brennstoffvolumen zuverlässig oberhalb des genannten minimalen Druckes ansammelt und abgibt.
15. Dosiersystem nach Anspruch 2, dadurch gekennzeichnet, daß die Brennstoffabgabepassage (110) stromab des Luftströmungsventils (42) direkt mit der Luftströmungspassage (44) verbunden ist.
16. Dosiersystem nach Anspruch 15, dadurch gekennzeichnet, daß der Brennstoff über eine Vielzahl von Öffnungen (111, 200-205) in die Luftströmungspassage eingeführt wird, daß die Vielzahl von Öffnungen so angeordnet ist, daß sie progressiv zur stromab liegenden Seite des Luftströmungsventils geöffnet werden, wenn das Ventil drehend geöffnet wird, wodurch zumindest eine Öffnung (111) stets zum stromab gerichteten Luftstrom freiliegt.
17. Dosiersystem nach Anspruch 12, dadurch gekennzeichnet, daß das Brennstoffströmungsventil ein Drehschieberventil ist und eine zylindrische Hülse (162) umfaßt, die für das Zusammenwirken mit einem Drehschieber (160, 164), der einen rechtwinklig ausgeschnittenen, mit der Öffnung (166) der Hülse zur Steuerung der Brennstoffströmung registrierenden Abschnitt mit einer Öffnung aufweist, ausgestattet ist.
18. Dosiersystem nach Anspruch 9, dadurch gekennzeichnet, daß eine Federkolbenanordnung (122, 124) vorgesehen ist, um das Kolbenventil (95) zum Abschließen der Brennstoffabgabepassage (110) zu bewegen, wenn der Druck in der Passage (103) unterhalb ein besonderes Niveau fällt, wodurch Brennstoffverdunstungsemissionen eliminiert werden.
19. Dosiersystem nach Anspruch 1, dadurch gekennzeichnet, daß die Verbindungen (246) zwischen dem Luftbalancesystem und der Druckrückgewinnungszwischenkammer-Strömungspassage (253) so angeordnet sind, daß der Unterschied zwischen dem aufstromseitigen Kammerdruck und dem Stagnationsdruck direkt stromauf der stromabliegenden Öffnung (250) nahezu der Hälfte des Druckunterschiedes im Luftdruckbalancesystem (270, 282, 284) entspricht.
EP81301380A 1980-03-31 1981-03-30 Analog-Vergaser Expired EP0037279B1 (de)

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US3409276A (en) * 1968-01-22 1968-11-05 Messerschmitt Boelkow Blohm Control mechanism for fuel injection apparatus
DE1576340A1 (de) * 1967-11-28 1970-04-23 Enneking Dr Rer Nat Heinz Laminar gesteuerte Benzineinspritzung
DE1922345A1 (de) * 1969-05-02 1971-03-25 Messerschmitt Boelkow Blohm Einrichtung zur Regelung der kontinuierlichen Zufuhr von fluessigem Brennstoff in Brennkraftmaschinen
US3807710A (en) * 1972-03-16 1974-04-30 L Bergamini Carburetor system
US4228777A (en) * 1979-02-01 1980-10-21 The Bendix Corporation Fuel control

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DE1576340A1 (de) * 1967-11-28 1970-04-23 Enneking Dr Rer Nat Heinz Laminar gesteuerte Benzineinspritzung
US3409276A (en) * 1968-01-22 1968-11-05 Messerschmitt Boelkow Blohm Control mechanism for fuel injection apparatus
DE1922345A1 (de) * 1969-05-02 1971-03-25 Messerschmitt Boelkow Blohm Einrichtung zur Regelung der kontinuierlichen Zufuhr von fluessigem Brennstoff in Brennkraftmaschinen
US3807710A (en) * 1972-03-16 1974-04-30 L Bergamini Carburetor system
US4228777A (en) * 1979-02-01 1980-10-21 The Bendix Corporation Fuel control

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DE3171540D1 (en) 1985-09-05
BR8107982A (pt) 1982-03-09
JPS57500523A (de) 1982-03-25

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