WO2004053325A1 - Device for maintaining a set pressure in the high pressure fuel reservoir of a common-rail injection system - Google Patents

Device for maintaining a set pressure in the high pressure fuel reservoir of a common-rail injection system Download PDF

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Publication number
WO2004053325A1
WO2004053325A1 PCT/DE2003/002515 DE0302515W WO2004053325A1 WO 2004053325 A1 WO2004053325 A1 WO 2004053325A1 DE 0302515 W DE0302515 W DE 0302515W WO 2004053325 A1 WO2004053325 A1 WO 2004053325A1
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WO
WIPO (PCT)
Prior art keywords
pressure
fuel
pressure pump
internal combustion
combustion engine
Prior art date
Application number
PCT/DE2003/002515
Other languages
German (de)
French (fr)
Inventor
Math Lemoure
Original Assignee
Robert Bosch Gmbh
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 Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Publication of WO2004053325A1 publication Critical patent/WO2004053325A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/02—Fuel-injection apparatus having several injectors fed by a common pumping element, or having several pumping elements feeding a common injector; Fuel-injection apparatus having provisions for cutting-out pumps, pumping elements, or injectors; Fuel-injection apparatus having provisions for variably interconnecting pumping elements and injectors alternatively
    • F02M63/0225—Fuel-injection apparatus having a common rail feeding several injectors ; Means for varying pressure in common rails; Pumps feeding common rails
    • F02M63/023—Means for varying pressure in common rails
    • F02M63/0235—Means for varying pressure in common rails by bleeding fuel pressure
    • F02M63/025—Means for varying pressure in common rails by bleeding fuel pressure from the common rail
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/20—Varying fuel delivery in quantity or timing
    • F02M59/34—Varying fuel delivery in quantity or timing by throttling of passages to pumping elements or of overflow passages, e.g. throttling by means of a pressure-controlled sliding valve having liquid stop or abutment
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/0012—Valves
    • F02M63/0014—Valves characterised by the valve actuating means
    • F02M63/0015—Valves characterised by the valve actuating means electrical, e.g. using solenoid
    • F02M63/0017—Valves characterised by the valve actuating means electrical, e.g. using solenoid using electromagnetic operating means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/0012—Valves
    • F02M63/0031—Valves characterized by the type of valves, e.g. special valve member details, valve seat details, valve housing details
    • F02M63/004—Sliding valves, e.g. spool valves, i.e. whereby the closing member has a sliding movement along a seat for opening and closing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/0012—Valves
    • F02M63/0031—Valves characterized by the type of valves, e.g. special valve member details, valve seat details, valve housing details
    • F02M63/0056—Throttling valves, e.g. having variable opening positions throttling the flow
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/02—Fuel-injection apparatus having several injectors fed by a common pumping element, or having several pumping elements feeding a common injector; Fuel-injection apparatus having provisions for cutting-out pumps, pumping elements, or injectors; Fuel-injection apparatus having provisions for variably interconnecting pumping elements and injectors alternatively
    • F02M63/0225—Fuel-injection apparatus having a common rail feeding several injectors ; Means for varying pressure in common rails; Pumps feeding common rails

Definitions

  • the invention relates to a device for maintaining a target pressure in a high-pressure fuel reservoir of a storage injection system of an internal combustion engine, with a pressure sensor, a high-pressure pump and a metering unit, which has a flow characteristic, wherein the pressure sensor provides a signal that indicates the pressure in the high-pressure fuel reservoir. and the metering unit limits the amount of fuel supplied by the high-pressure pump to the high-pressure fuel reservoir as a function of the signal from the pressure sensor, in that the metering unit limits the amount of fuel that is supplied to the high-pressure pump.
  • the invention further relates to a device for metering fuel to a high-pressure pump for maintaining a target pressure in a high-pressure fuel reservoir of a storage injection system of an internal combustion engine with a pressure sensor, the The device forms a metering unit that has a flow characteristic, the pressure sensor provides a signal that indicates the pressure in the high-pressure fuel storage device, and the metering unit limits the amount of fuel supplied by the high-pressure pump to the high-pressure fuel reservoir as a function of the signal from the pressure sensor by which the amount of fuel is measured limited, which is delivered to the high pressure pump.
  • Devices of this type are used in series in common-rail injection systems for diesel internal combustion engines with direct injection.
  • the common rail corresponds to a high-pressure fuel reservoir from which several injection nozzles or injectors are supplied with fuel.
  • the high pressure fuel propagates through high pressure lines to the injectors and is released via electrical actuation of an actuator in the injector on injection openings in the injector.
  • the high-pressure fuel in the common rail is generated by a high-pressure pump, which is supplied with fuel from a tank via a low-pressure pump and upstream fuel fillers.
  • the pressure in the common rail is detected by a pressure sensor and compared in a control unit with a predetermined setpoint. If the actual value deviates from the target value, the amount of fuel required by the high pressure pump is limited on the high pressure side and / or low pressure side.
  • a pressure control valve arranged on the common rail, which, when the rail pressure is too high, directs the excess fuel supplied by the high pressure pump via a leakage line to the fuel tank.
  • a metering unit arranged between the low-pressure pump and the high-pressure pump is used on the low-pressure side of the high-pressure pump, which limits the quantity of fuel supplied by the low-pressure pump to the suction side of the high-pressure pump.
  • This limitation on the suction side has the advantage that only the amount of fuel that is required by the internal combustion engine at its current operating point is demanded by the high-pressure pump, injection pressure, injection amount and leakage quantities playing a role. This means that no unnecessary compression energy is consumed. In other words, no energy is used to raise the pressure of an excess amount of fuel that is not required by the internal combustion engine to the rail pressure level. This reduces the power consumption of the high-pressure pump, which contributes to the most efficient possible operation of the internal combustion engine.
  • the high-pressure pump with the maximum delivery volume fuel m requests the common rail.
  • the above-mentioned pressure control valve on the common rail is used to derive the amount of fuel that is not required at the current operating point of the internal combustion engine and is therefore excess.
  • the increased fuel demand from the high-pressure pump results in an energy input into the fuel, which heats the fuel, which counteracts the excretion.
  • the high-pressure pump is throttled not on the suction side but on the high-pressure side by the pressure control valve on the common rail mentioned above. Raising the
  • Fuel pressure levels by the high pressure pump result in an energy input into the fuel, which m m Mapped circle of tank, low pressure pump, high pressure pump, pressure control valve and tank in a desired heating of the fuel in the tank.
  • an internal combustion engine has a comparatively low fuel consumption when idling. For this reason, the amount of fuel to be supplied by the high-pressure pump to the common rail as a high-pressure fuel reservoir is comparatively small. If the demand for the high-pressure pump is limited on the suction side by a regulated metering unit, undesired fluctuations in the pressure in the high-pressure fuel accumulator have been observed when the internal combustion engine is idling. These pressure fluctuations only occurred above a certain number of operating hours, which corresponds to a mileage of approximately 10,000 km in motor vehicles. Their amplitude was about +/- 20 bar at a rail pressure level on the order of about 300 bar. These pressure fluctuations can be caused and / or intensified by age-dependent and / or production-dependent scattering of the system components used.
  • the object of the invention is to prevent the pressure fluctuations in the high-pressure fuel accumulator observed when the internal combustion engine is idling, without causing losses in the efficiency of the internal combustion engine operation.
  • a loss would result, for example, from the fact that, when the internal combustion engine is idling, a larger amount of fuel is deliberately delivered to the high-pressure fuel reservoir than is injected into the combustion chamber of the internal combustion engine via the injectors. The excess amount of fuel could be diverted to the tank via the pressure control valve mentioned above.
  • this procedure would require a pressure control valve between the high-pressure pump and the high-pressure fuel reservoir.
  • the object of the invention is also to prevent the observed rail pressure fluctuations even in systems without a pressure control valve on the high pressure side.
  • This object is achieved in a device for maintaining a setpoint pressure in a high-pressure fuel accumulator of the type mentioned at the outset in that the flow characteristic curve at a flow rate which corresponds to the idling requirement of the internal combustion engine has such a flat course that changes occur in the undisturbed idling operation of the internal combustion engine of the pressure sensor signal does not lead to an interruption in the amount of fuel supplied by the high pressure pump.
  • this object is achieved in a device for metering fuel into a high-pressure pump of the type mentioned at the outset in that the flow characteristic curve for a flow that corresponds to the Idling requirement of the internal combustion engine corresponds to such a flat course that changes in the pressure sensor signal occurring in the undisturbed idling operation of the internal combustion engine do not lead to an interruption of the fuel quantity supplied by the high pressure pump.
  • the invention is based on the knowledge that the undesired rail pressure fluctuations observed are caused by interruptions in the delivery of fuel from the high-pressure pump to the high-pressure fuel reservoir.
  • Radial piston pumps are usually used as high-pressure pumps for accumulator injection systems. These radial piston pumps have valves on the suction side which only open above a predetermined opening pressure.
  • the high-clruc pump ⁇ i ⁇ -h the metering unit is throttled too much, it may happen that these valves do not open, so the high-pressure pump does not draw in any fuel and therefore does not deliver any fuel on the high-pressure side. This leads to a drop in the rail pressure, which is registered by the pressure sensor and triggers a reduction in throttling by the metering unit. Dadurcn .. the opening pressure of the valves on the suction side of the high pressure pump is exceeded again and the high pressure pump starts to demand again. As a result, the pressure in the high-pressure fuel reservoir rises again, which is registered by the pressure sensor and leads to an increased throttling of the high-pressure pump by the metering unit.
  • the flow characteristic of the metering unit which is designed flat according to the invention, has the effect that the throttling on the suction side of the high-pressure pump can be regulated more finely, more uniformly and with less fluctuation range. This advantageously prevents the valves on the suction side of the high-pressure pump from falling below the opening pressure. As a result, interruptions in the high-pressure pump requirement are avoided, which avoids an associated drop in the rail pressure. This alone leads to less pronounced counter-reactions by the metering unit, so that overall a more uniform throttling of the suction side of the high-pressure pump is achieved. These advantageous effects are achieved without a loss in the efficiency of the high-pressure pump operation, that is to say in particular without an increase in an excess amount of fuel provided by the high-pressure pump.
  • the metering unit has a flow cross-section which also determines the amount of fuel supplied to the high-pressure pump and which is variable as a function of the signal from the pressure sensor
  • variable flow cross-section is used to throttle the high-pressure pump.
  • a variable flow cross-section is particularly well suited for uniform throttling, for example in comparison to the digital opening and / or closing of a constant flow cross-section.
  • the metering unit is controlled or regulated depending on the driving behavior and pressure map, that the amount of fuel delivered to the high pressure pump is limited.
  • the current pressure in the rail is measured via the pressure sensor and compared with the target pressure. In accordance with the comparison result, the fuel quantity to be delivered to the high-pressure pump is varied via the metering unit.
  • the flow cross-section is determined by the free cross-section of an opening in a wall of a cylinder, the opening being able to be completely or partially covered by a control piston movable in the cylinder, so that the free cross-section coincides with the position of the control piston in the cylinder changes.
  • This configuration has the advantage that the position of a control piston, which is movable in a cylinder, can be varied continuously and precisely, so that as a result there is a constant and precise variation of the free cross section which determines the flow cross section.
  • control piston is hollow and has an opening so that the free cross section is defined by a covering of the opening in the wall of the cylinder and the opening in the control piston.
  • This embodiment has the particular advantage that the change in the flow cross section depending on the position of the control piston can be influenced by a changed size and shape of the opening in the control piston. This enables the realization of different flow characteristics and flow rates of one metering unit by using different control pistons. This makes the use of standard components one Metering unit for a variety of high pressure pumps and internal combustion engines possible, the
  • Standard metering unit only has to be adapted to a specific high-pressure pump type and / or internal combustion engine type by using a corresponding control piston.
  • the electromagnetic actuating element has a coil and an armature movable in the coil and that the armature is deflected from a rest position in proportion to an electrical current flowing through the coil.
  • This configuration has the advantage that the position of the control piston can be controlled by a technically easily controllable change in a coil current. Instead of a pure proportionality, a different kind of dependence of the armature deflection on the coil current is of course also possible.
  • a duty cycle of the electrical current flowing through the coil is varied depending on the signal of the current sensor.
  • the mean value of the current intensity fluctuating with the duty cycle sets a medium control piston position and that, with an appropriate choice of the duty cycle frequency, the fluctuation of the current intensity additionally acts as a dither signal that the control piston n has a fast Low-amplitude oscillation offset around its central position. This prevents the occurrence of static friction and reduces the breakaway torque of the control piston in the event of a desired change in its position. It is further preferred that the cross section is completely open in the currentless state.
  • This configuration advantageously has the effect that the flow cross section is fully open in the event of a fault, which prevents undesired throttling of the high-pressure pump and thus ensures the availability of the common rail system.
  • Such undesirable throttling could otherwise result in the demand for the high-pressure pump being severely restricted, which could lead to reduced performance of the internal combustion engine or to the vehicle stopping.
  • the flat course of the characteristic curve is generated in that movements of the control piston in the undisturbed idling of the internal combustion engine lead to smaller cross-sectional changes than when the internal combustion engine is operated outside of idling.
  • This embodiment has the advantage that even with a standard metering unit in which the control piston moves with the armature proportional to a coil current, differently flat, non-linear and non-proportional characteristic curves can be generated by the shape of the openings in the cylinder and / or control piston , This also enables the use of standard components of a metering unit for use in various high-pressure pumps and internal combustion engines.
  • the contours of the opening in the control piston are fixed in such a way that the characteristic curve is non-linear.
  • This embodiment has the advantage that the course of the characteristic curve can be determined by the design of the control piston, that is to say by the course of the contours of the opening in the control piston, so that the corresponding design of different control pistons is adapted to adapt a standard metering unit to different high-pressure pumps and / or internal combustion engines allowed.
  • the metering unit has a modular structure, different control pistons being able to be combined with the other components of the metering unit, and the different control pistons differing in different shapes and sizes of the opening in the control piston.
  • This configuration reduces the number of parts that have to be used to manufacture metering units for various high-pressure pumps and / or internal combustion engines, which results in simplified and more cost-effective production and storage.
  • FIG 1 shows the technical environment in which the invention has its effect
  • FIG. 2 shows the function of some components from FIG. 1 in the form of an equivalent switch
  • FIG. 3 shows an exemplary embodiment of a metering unit 32
  • FIG. 4 shows a flow characteristic Q (I);
  • FIG. 5 characteristic curves for a first embodiment of an opening in the control piston of the metering unit.
  • the number 10 in FIG. 1 denotes a high-pressure fuel reservoir (common rail) from which injectors 12 are supplied with fuel under injection pressure.
  • the injectors 12 are opened by electrical injection pulse width signals, which are output by a control device t 14, so that fuel is injected into the combustion chambers (not shown) of an internal combustion engine.
  • the injection pulse widths are formed in the control unit 14 using control programs and data stored in the control unit 14 using various input signals.
  • Essential input signals are the signal from a driver's request transmitter 16 and the signal from a speed transmitter 18, which indicates the speed of the internal combustion engine.
  • the number 20 stands representative of other signal transmitters, for example air mass sensors, temperature sensors,
  • the fuel is first perforated from a fuel anchor 22 by a gear pump 24 via a prefilter 26 and a main filter 28 to a high pressure pump 30.
  • the gear pump 24 is usually flanged to the high-pressure pump 30, so that both pumps can be driven by the internal combustion engine through a common shaft 31.
  • an electric fuel pump could also take over the low-pressure fuel requirement from the tank 22 to the high-pressure pump 30.
  • the fuel required by the gear pump 24 with low pressure flows via internal supply channels to the metering unit 32, which is connected upstream of the high-pressure pump 30 in terms of flow.
  • the metering unit 32 throttles the amount of fuel that flows to the suction side of the high-pressure pump 30 as a function of a control signal that is provided by the control unit 14.
  • the amount of fuel supplied to the high-pressure pump 30 is delivered in parallel from the high-pressure side of the high-pressure pump 30 to the high-pressure fuel reservoir 10 and to a pressure regulating valve 34, which is also controlled / regulated by the control device 14.
  • the pressure control valve 34 When the pressure control valve 34 is open, the fuel required by the high pressure pump 30 flows back to the tank 22 via the pressure control valve 34. In addition, the injectors have a leakage amount, which is also returned to the tank.
  • the pressure control valve 34 When the pressure control valve 34 is closed, it flows from the high pressure pump 30 required fuel, however, in the fuel high-pressure accumulator 10 and increases the fuel pressure within the fuel high-pressure accumulator 10. This pressure is registered by a pressure sensor 36, which delivers a corresponding signal to the control unit 14.
  • the control device 14 subsequently controls the metering unit 32 and / or the pressure control valve 34 in such a way that the desired fuel pressure is set in the high-pressure fuel reservoir 10.
  • Figure 2 illustrates the sequential arrangement of the gear pump 24, which can be more generally referred to as a low-pressure pump 24, the metering unit 32 and the high-pressure pump 30, the fuel flow between the main filter 28 and the high-pressure fuel reservoir 10.
  • the metering unit 32 throttles that of the low-pressure pump 24 provided fuel flow on the suction side of the high-pressure pump 30.
  • the high-pressure pump 30 is a radial piston pump with three pump elements 38, each having a pump piston 42, which is movably guided in a pump cylinder 40 and by an eccentric drive shaft 31 is operated.
  • the high-pressure pump 30 By periodically actuating the pump pistons 40, the high-pressure pump 30 sucks fuel from its suction side 50 via low-pressure valves 44 into the pump cylinder 42 and requests the fuel under high pressure via high-pressure valves 46 to the high-pressure side 54 of the high-pressure pump 30 and then to the high-pressure fuel reservoir 10 and the pressure control valve 34 2 also shows a so-called zero delivery throttle 52, via which fuel from the suction side 50, which is not drawn in by the pump elements 38 of the high-pressure pump 30, can flow back to the inlet of the low-pressure pump 24 or to the tank 22.
  • FIG. 3 shows an exemplary embodiment of a metering unit 32.
  • the metering unit 32 has a plastic housing 56, in which electrical connections 58 are cast in.
  • the plastic housing 56 has a magnetic pot 64 connected in which a coil 62 is held by a holder 63.
  • An armature 60 is movably guided in the coil 62.
  • the armature 60 extends through a magnetic core 66 which is connected to the magnetic pot 64.
  • the magnetic core 66 has a hollow cylinder 69, in which a hollow control piston 68 is movably guided.
  • the control piston 68 is actuated by the armature 60 against the restoring force of a spring 70.
  • the cylinder 69 in the magnetic core 66 has openings 74 through which an annular groove 76 in the lateral surface of the cylinder 69 is supplied with fuel from the low-pressure pump 24.
  • the fuel in the annular groove 76 coils around the control piston 68 and, if an opening in the control piston 68 at least partially coincides with the annular groove 76 or the openings 74 in the lateral surface of the cylinder 69, flows through the opening 72 and the interior of the hollow control piston 68 the downwardly open cylinder 69 to the high pressure pump 30.
  • FIG. 4 schematically shows a possible characteristic of the flow Q over the coil current I of the metering unit 32. As is immediately apparent from the illustration in FIG. 4, this characteristic corresponds to a normally open metering unit 32, as is preferably used.
  • FIG. 5 shows a first configuration of the control piston 68 with the resulting characteristic curves 82, 84 in the top right corner.
  • the non-linear, curved profile of the characteristic curves 82, 84 results as a result of the trapezoidal or triangular configuration of the opening 72 in the control piston 68.
  • FIG. 6 shows linear curves of characteristic curves 78, 80 in pieces, as is shown schematically in section when using the top right in FIG. 6 shown control piston 68 result.
  • the control piston 68 according to FIG. 6 is distinguished by a slit zgeomet ⁇ e, in which an upper narrow slit merges stepwise x p a lower wider slit.
  • the upper narrow slot is assigned to the flatter wedge of the characteristic curve in FIG. 6, that is to say the common right-hand characteristic curve branch in FIG. 6.
  • the larger opening cross-section corresponds to the left branches of the characteristic curves 78, 80, which run comparatively steeply.
  • the different slope of the two characteristic curves 78, 80 corresponds to lower slits of the opening 72 in the control piston 68 of different widths. Both characteristic curves 78, 80 have the flat characteristic curve part running to the right in common. Otherwise, the characteristic curves 78, 80 differ in the maximum flow rate, which is much higher for the characteristic curve 80 than for the characteristic curve 78.
  • the characteristic curve 80 is therefore associated with an injection system which is designed for a greater fuel requirement. Analogous considerations apply to the two characteristic curves 82, 84 in FIG. 5.

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

Abstract

A device for maintaining a set pressure in the high pressure fuel reservoir (10) of a common-rail injection system on an internal combustion engine is disclosed, comprising a pressure sensor (36), a high pressure pump (30) and a metering device (32). The metering device (32) is provided with a flow curve. The pressure sensor (36) produces a signal for the pressure in the high pressure fuel reservoir and the metering device (32) limits the amount of fuel supplied to the high-pressure fuel reservoir by the high pressure pump (30), depending on the signal from the pressure sensor, by limiting the amount of fuel supplied to the high pressure pump. The device is characterised in that the flow curve has a shape at a flow corresponding to the idle requirement for the internal combustion engine which is sufficiently flat that changes in the pressure sensor signal arising during continuous idle operation of the internal combustion engine do not lead to an interruption of the fuel supply from the high pressure pump. A metering device (32) with such a curve is also disclosed.

Description

Vorrichtung zur Aufrechterhaltunq eines Solldruckes im Kraftstoff-Hochdruckspeicher eines SpeichereinspritzsystemsDevice for maintaining a target pressure in the high-pressure fuel reservoir of a storage injection system
Stand der TechnikState of the art
Die Erfindung betrifft eine Vorrichtung zur Aufrechterhaltung eines Solldruckes in einem Kraftstofr- Hochdruckspeicher eines Speichereinspritzsystems eines Verbrennungsmotors, mit einem Drucksensor, einer Hochdruckpumpe und einer Zumesseinheit, die eine Durchflusskennlinie aufweist, wobei αer Drucksensor ein Signal bereitstellt, dass den Druck im Kraftstoff- Hochdruckspeicher angibt, und die Zumesseinheit die von der Hochdruckpumpe an den Kraftstoff-Hochdruckspeicher gelieferte Kraftstoffmenge in Abhängigkeit vom Signal des Drucksensors begrenzt, indem die Zumesseinheit die Kraftstoffmenge beschrankt, die an die Hochdruckpumpe geliefert wird.The invention relates to a device for maintaining a target pressure in a high-pressure fuel reservoir of a storage injection system of an internal combustion engine, with a pressure sensor, a high-pressure pump and a metering unit, which has a flow characteristic, wherein the pressure sensor provides a signal that indicates the pressure in the high-pressure fuel reservoir. and the metering unit limits the amount of fuel supplied by the high-pressure pump to the high-pressure fuel reservoir as a function of the signal from the pressure sensor, in that the metering unit limits the amount of fuel that is supplied to the high-pressure pump.
Die Erfindung betrifft ferner eine Vorrichtung zur Zumessung von Kraftstoff zu einer Hochdruckpumpe zur Aufrechterhaltung eines Solldruckes in einem Kraftstoff- Hochdruckspeicher eines Speichereinspritzsystems eines Verbrennungsmotors mit einem Drucksensor, wobei die Vorrichtung eine Zumesseinheit bildet, die eine Durchflusskennlime aufweist, der Drucksensor ein Signal bereitstellt, das den Druck im Kraftstoff-Hochdruckspeicner angibt, und die Zumesseinheit die von der Hochdruckpumpe an den Kraftstoffhochdruckspeicher gelieferte Kraftstoffmenge in Abhängigkeit vom Signal des Drucksensors begrenzt, n dem Sie die Kraftstoffmenge beschrankt, die an d e Hochdruckpumpe geliefert wird.The invention further relates to a device for metering fuel to a high-pressure pump for maintaining a target pressure in a high-pressure fuel reservoir of a storage injection system of an internal combustion engine with a pressure sensor, the The device forms a metering unit that has a flow characteristic, the pressure sensor provides a signal that indicates the pressure in the high-pressure fuel storage device, and the metering unit limits the amount of fuel supplied by the high-pressure pump to the high-pressure fuel reservoir as a function of the signal from the pressure sensor by which the amount of fuel is measured limited, which is delivered to the high pressure pump.
Derartige Vorrichtungen werden bei Common-Rail- Emspπtzsystemen für Diesel-Verbrennungsmotoren mit Direkteinspritzung in Serie verwendet.Devices of this type are used in series in common-rail injection systems for diesel internal combustion engines with direct injection.
Dabei entspricht das Common-Rail einem Kraftstoff- Hochdruckspeicher, aus dem mehrere Einspritzdüsen oder Injektoren mit Kraftstoff versorgt werden. Der Kraftstoff- Hochdruck pflanzt sich über Hochdruckleitungen zu den Injektoren fort und wird über elektrische Betätigung eires Stellgliedes im Injektor auf Einspritzoffnungen im Injektor freigegeben. Der Kraftstoff-Hochdruck im Common-Rail wird von einer Hochdruckpumpe erzeugt, die über eine Niederdruckpumpe und vorgeschaltete Kraftstofff llter mit Kraftstoff aus einem Tank versorgt wird.The common rail corresponds to a high-pressure fuel reservoir from which several injection nozzles or injectors are supplied with fuel. The high pressure fuel propagates through high pressure lines to the injectors and is released via electrical actuation of an actuator in the injector on injection openings in the injector. The high-pressure fuel in the common rail is generated by a high-pressure pump, which is supplied with fuel from a tank via a low-pressure pump and upstream fuel fillers.
Der Druck im Common-Rail wird über einen Druckseπsor erfasst und in einem Steuergerat mit einem vorgegebenen Sollwert verglichen. Bei Abweichungen des IST- ertes von dem Sollwert wird die von der Hochdruckpumpe geforderte Kraftstoffmenge hochdruckseitig und/oder niederdruckseir ια begrenzt. Zur hochdruckseitigen Begrenzung ist es bekannt, ein am Common-Rail angeordnetes Druckregelventil anzusteuern, das bei zu hohem Raildruck den von der Hochdruckpumpe gelieferten überschüssigen Kraftstoff über eine Leckageleitung zum Kraftstofftank leitet. Auf der Niederdruckseite der Hochdruckpumpe wird bei bekannten Systemen eine zwischen der Niederdruckpumpe und der Hochdruckpumpe angeordnete Zumesseinheit verwendet, die die von der Niederdruckpumpe an die Saugseite der Hochdruckpumpe gelieferte Kraftstoffmenge begrenzt. Diese saugseitige Begrenzung besitzt den Vorteil, dass lediglich diejenige Kraftstoffmenge über die Hochdruckpumpe gefordert wird, die vom Verbrennungsmotor in seinem aktuellen Betriebspunkt benotigt wird, wobei Einspritzdruck, Einspritzmenge und Leckagemengen eine Rolle spielen. Dadurch wird keine unnötige Verdichtungsenergie verbraucht. Mit anderen Worten: Es wird keine Energie verbraucht, um den Druck einer Kraftstoff-Uberschussmenge, die vom Verbrennungsmotor nicht benotigt wird, auf Raildruckniveau zu heben. Dadurch wird die Leistungsaufnahme der Hochdruckpumpe verringert, was zu einem möglichst effizienten Betrieb des Verbrennungsmotors beitragt.The pressure in the common rail is detected by a pressure sensor and compared in a control unit with a predetermined setpoint. If the actual value deviates from the target value, the amount of fuel required by the high pressure pump is limited on the high pressure side and / or low pressure side. To limit the pressure on the high pressure side, it is known to control a pressure control valve arranged on the common rail, which, when the rail pressure is too high, directs the excess fuel supplied by the high pressure pump via a leakage line to the fuel tank. In known systems, a metering unit arranged between the low-pressure pump and the high-pressure pump is used on the low-pressure side of the high-pressure pump, which limits the quantity of fuel supplied by the low-pressure pump to the suction side of the high-pressure pump. This limitation on the suction side has the advantage that only the amount of fuel that is required by the internal combustion engine at its current operating point is demanded by the high-pressure pump, injection pressure, injection amount and leakage quantities playing a role. This means that no unnecessary compression energy is consumed. In other words, no energy is used to raise the pressure of an excess amount of fuel that is not required by the internal combustion engine to the rail pressure level. This reduces the power consumption of the high-pressure pump, which contributes to the most efficient possible operation of the internal combustion engine.
Andererseits kann es in der kalten Jahreszeit erwünscht sein, den Kraftstoff zu erwarmen, um eine temperaturbedingte Ausscheidung von Paraffin aus dem Kraftstoff zu verhindern. In diesem Fall fordert die Hochdruckpumpe mit dem maximalen Fordervolumen Kraftstoff m das Common Rail. Über das oben genannte Druckregelventil am Common Rail wird die im aktuellen Betriebspunkt des Verbrennungsmotors nicht benotigte und damit uoerschuss ige Kraf stoffmenge abgeleitet. Die erhöhte Kraftstoffforderung durch die Hochdruckpumpe hat einen Energieeintrag in den Kraftstoff zur Folge, der den Kraftstoff erwärmt, was der Ausscheidung entgegenwirkt. Mit anderen Worten: In diesem Fall wird die Hochdruckpumpe nicht saugseitig, sondern hochdruckseitig durch das oben genannte Druckregelventil am Common-Rail gedrosselt. Das Anheben desOn the other hand, in the cold season it may be desirable to heat the fuel to prevent paraffin from exiting the fuel due to temperature. In this case, the high-pressure pump with the maximum delivery volume fuel m requests the common rail. The above-mentioned pressure control valve on the common rail is used to derive the amount of fuel that is not required at the current operating point of the internal combustion engine and is therefore excess. The increased fuel demand from the high-pressure pump results in an energy input into the fuel, which heats the fuel, which counteracts the excretion. In other words: In this case, the high-pressure pump is throttled not on the suction side but on the high-pressure side by the pressure control valve on the common rail mentioned above. Raising the
Kraftstoffdruckniveaus durch die Hochdruckpumpe hat einen Energieeintrag in den Kraftstoff zur Folge, der sich m dem Kreis aus Tank, Niederdruckpumpe, Hochdruckpumpe, Druckregelventil und Tank in einer gewünschten Erwärmung des Kraftstoffs im Tank abbildet.Fuel pressure levels by the high pressure pump result in an energy input into the fuel, which m m Mapped circle of tank, low pressure pump, high pressure pump, pressure control valve and tank in a desired heating of the fuel in the tank.
Bei Systemen, die sowohl über eine Steuer- und/oder regelbare Zumesseinheit zwischen Niederdruckpumpe und Hochdruckpumpe als auch über ein hochdruckseitig angeordnetes Druckregelventil verfugen, kann daher zwischen einer hochdruckseitigen Begrenzung durch das Druckregelventil und einer niederdruckseitigen Begrenzung durch die Zumesseinheit umgeschaltet werden.In systems that have both a control and / or adjustable metering unit between the low-pressure pump and high-pressure pump and a pressure control valve on the high-pressure side, it is therefore possible to switch between a high-pressure side limitation by the pressure control valve and a low-pressure side limitation by the metering unit.
Im Leerlauf besitzt ein Verbrennungsmotor bekanntlich einen vergleichsweise geringen Kraftstoffbedarf. Aus diesem Grund ist die von der Hochdruckpumpe an das Common-Rail als Kraftstoff-Hochdruckspeicher zu liefernde Kraf stoffmenge vergleichsweise gering. Bei einer saugseitigen Begrenzung der Fordermenge der Hochdruckpumpe durch e ne geregelte Zumesseinheit sind im Leerlauf des Verbrennungsmotors unerwünschte Schwankungen des Druckes im Kraftstoff- Hochdruckspeicher beobachtet worden. Diese Druckschwankungen traten erst oberhalb einer bestimmten Betπebsstundenz.ahl, die bei Kraftfahrzeugen einer Kilomterlaufleistung von etwa 10.000 km entspricht, auf. Ihre Amplitude betrug etwa +/- 20 bar bei einem Raildruckniveau in der Größenordnung von etwa 300 bar. Diese Druckschwankungen können durch alterungsabhangige und/oder fertigungsabhangige Streuungen der verwendeten Systemkomponenten verursacht und/oder verstärkt werden.As is well known, an internal combustion engine has a comparatively low fuel consumption when idling. For this reason, the amount of fuel to be supplied by the high-pressure pump to the common rail as a high-pressure fuel reservoir is comparatively small. If the demand for the high-pressure pump is limited on the suction side by a regulated metering unit, undesired fluctuations in the pressure in the high-pressure fuel accumulator have been observed when the internal combustion engine is idling. These pressure fluctuations only occurred above a certain number of operating hours, which corresponds to a mileage of approximately 10,000 km in motor vehicles. Their amplitude was about +/- 20 bar at a rail pressure level on the order of about 300 bar. These pressure fluctuations can be caused and / or intensified by age-dependent and / or production-dependent scattering of the system components used.
Insbesondere alterungsbedingte Streuungen können sich mit zunehmender Kilometerlaufleistung weiter verandern, so dass eine weitere Vergrößerung solcher Druckschwankungen bis zu einer Größenordnung, in der sie möglicherweise für einen Fahrer spurbar werden, möglich erscheint. Vor diesem Hintergrund besteht die Aufgabe der Erfindung darin, die im Leerlaufbetrieb des Verbrennungsmotors beobachteten Druckschwankungen im Kraftstoff- Hochdruckspeicher zu verhindern, ohne dabei Einbußen in der Effizienz des Verbrennungsmotorbetriebs hervorzurufen. Eine solche Einbuße wurde sich beispielsweise daraus ergeben, dass im Leerlauf des Verbrennungsmotors bewusst eine größere Menge an Kraftstoff an den Kraftstoff- Hochdruckspeicher geliefert wird, als über die Injektoren in Verbrennungsraume des Verbrennungsmotors eingespritzt wird. Die überschüssige Kraftstoffmenge konnte über das oben genannte Druckregelventil zum Tank abgeleitet werden. Neben einer Wirkungsgradeiήbuße wurde dieses Vorgehen aber ein Druckregelventil zwischen Hochdruckpumpe und Kraftstoff-Hochdruckspeicher zwingend erfordern. Die Aufgabe der Erfindung besteht jedoch auch darin, die beobachteten Raildruckschwankungen auch bei Systemen ohne hochdruckseitiges Druckregelventil zu verhindern.In particular, age-related scatter can change further with increasing mileage, so that a further increase in such pressure fluctuations up to an order of magnitude in which they can possibly be felt by a driver appears possible. Against this background, the object of the invention is to prevent the pressure fluctuations in the high-pressure fuel accumulator observed when the internal combustion engine is idling, without causing losses in the efficiency of the internal combustion engine operation. Such a loss would result, for example, from the fact that, when the internal combustion engine is idling, a larger amount of fuel is deliberately delivered to the high-pressure fuel reservoir than is injected into the combustion chamber of the internal combustion engine via the injectors. The excess amount of fuel could be diverted to the tank via the pressure control valve mentioned above. In addition to a loss of efficiency, this procedure would require a pressure control valve between the high-pressure pump and the high-pressure fuel reservoir. However, the object of the invention is also to prevent the observed rail pressure fluctuations even in systems without a pressure control valve on the high pressure side.
Diese Aufgabe wird bei einer Vorrichtung zur Aufrechterhaltung eines Solldruckes in einem Kraftstoff- Hochdruckspeicher der eingangs genannten Art dadurch gelost, dass die Durchflusskennlinie bei einem Durchfluss, der dem Leerlaufbedarf des Verbrennungsmotors entspricht, einen so flachen Verlauf aufweist, das im ungestörten Leerlaufbetrieb des Verbrennungsmotors auftretende Änderungen des Drucksensorsignals nicht zu einer Unterbrechung der von der Hochdruckpumpe gelieferten Kraftstoffmenge fuhren.This object is achieved in a device for maintaining a setpoint pressure in a high-pressure fuel accumulator of the type mentioned at the outset in that the flow characteristic curve at a flow rate which corresponds to the idling requirement of the internal combustion engine has such a flat course that changes occur in the undisturbed idling operation of the internal combustion engine of the pressure sensor signal does not lead to an interruption in the amount of fuel supplied by the high pressure pump.
Ferner wird diese Aufgabe bei einer Vorrichtung zur Zumessung von Kraftstoff zu einer Hochdruckpumpe der eingangs genannten Art dadurch gelost, dass die Durchflusskennlinie bei einem Durchfluss, der dem Leerlaufbedarf des Verbrennungsmotors entspricnt, einen so flachen Verlauf aufweist, dass im ungestörten Leerlaufbetrieb des Verbrennungsmotors auftretende Änderungen des Drucksensorsignals nicht zu einer Unterbrechung der von der Hochdruckpumpe gelieferten Kraftstoffmenge fuhren.Furthermore, this object is achieved in a device for metering fuel into a high-pressure pump of the type mentioned at the outset in that the flow characteristic curve for a flow that corresponds to the Idling requirement of the internal combustion engine corresponds to such a flat course that changes in the pressure sensor signal occurring in the undisturbed idling operation of the internal combustion engine do not lead to an interruption of the fuel quantity supplied by the high pressure pump.
Vorteile der ErfindungAdvantages of the invention
Die Erfindung basiert auf der Erkenntnis, dass die beobachteten unerwünschten Raildruckschwankungen durch Unterbrechungen der Lieferung von Kraftstoff von der Hochdruckpumpe an den Kraftstoff-Hochdruckspeicher verursacht werden. Als Hochdruckpumpen für Speichereinspritzsysteme werden üblicherweise Radialkolbenpumpen verwendet. Diese Radialkolbenpumpen weisen saugseitig Ventile auf, die erst oberhalb eines vorbestimmten Offnungsdruckes offnen.The invention is based on the knowledge that the undesired rail pressure fluctuations observed are caused by interruptions in the delivery of fuel from the high-pressure pump to the high-pressure fuel reservoir. Radial piston pumps are usually used as high-pressure pumps for accumulator injection systems. These radial piston pumps have valves on the suction side which only open above a predetermined opening pressure.
Bei einer zu starken Androsselung der Hochclruc pumpe α i^-h die Zumesseinheit kann es dazu kommen, dass diese Ventile nicht offnen, die Hochdruckpumpe daher keinen Kraftstoff ansaugt und daher auch hochdruckseitig keinen Kraftstoff liefert. Dies fuhrt zu einem Absinken des Raildruckes, das vom Drucksensor registriert wird und eine Verringerung αer Androsselung durch die Zumesseinheit auslost. Dadurcn ..ird der Offnungsdruck der Ventile an der Saugseite der Hochdruckpumpe wieder überschritten und die Hochdruckpumpe beginnt wieder zu fordern. Dadurch steigt der Druck im Kraftstoff-Hochdruckspeicher wieder an, was über den Drucksensor registriert wird und zu einer verstärkten Androsselung der Hochdruckpumpe durch die Zumesseinheit fuhrt.If the high-clruc pump α i ^ -h the metering unit is throttled too much, it may happen that these valves do not open, so the high-pressure pump does not draw in any fuel and therefore does not deliver any fuel on the high-pressure side. This leads to a drop in the rail pressure, which is registered by the pressure sensor and triggers a reduction in throttling by the metering unit. Dadurcn .. the opening pressure of the valves on the suction side of the high pressure pump is exceeded again and the high pressure pump starts to demand again. As a result, the pressure in the high-pressure fuel reservoir rises again, which is registered by the pressure sensor and leads to an increased throttling of the high-pressure pump by the metering unit.
Die periodische Wiederholung dieses Zyklusses fuhrt zu den beobachteten unerwünschten
Figure imgf000009_0001
. Die erfmdungsgemaß flach ausgestaltete Durchfluss ennlinie der Zumesseinheit bewirkt, dass sich die Androsselung auf der Saugseite der Hochdruckpumpe feiner, gleichmäßiger und mit geringerer Schwankungsbreite regulieren lasst. Dadurch kann vorteilhafterweise ein Unterschreiten der Of nungsdruC e der Ventile an der Saugseite der Hochdruckpumpe vermieden werden. Als Folge werden Unterbrechungen der Forderung der Hochdruckpumpe vermieden, was einen zugehörigen Abfall des Raildrucks vermeidet. Bereits dadurch kommt es zu weniger stark ausgeprägten Gegenreaktionen der Zumesseinheit, so dass sich insgesamt eine gleichmaßigere Androsselung der Saugseite der Hochdruckpumpe einstellt. Diese vorteilhaften Wirkungen werden ohne Einbußen beim Wirkungsgrad des Hochdruckpumpenbetriebes, also inbesondere ohne eine Vergrößerung einer von der Hochdruckpumpe bereitgestellten Uberschussmenge an Kraftstoff, erreicht.The periodic repetition of this cycle leads to the observed unwanted
Figure imgf000009_0001
, The flow characteristic of the metering unit, which is designed flat according to the invention, has the effect that the throttling on the suction side of the high-pressure pump can be regulated more finely, more uniformly and with less fluctuation range. This advantageously prevents the valves on the suction side of the high-pressure pump from falling below the opening pressure. As a result, interruptions in the high-pressure pump requirement are avoided, which avoids an associated drop in the rail pressure. This alone leads to less pronounced counter-reactions by the metering unit, so that overall a more uniform throttling of the suction side of the high-pressure pump is achieved. These advantageous effects are achieved without a loss in the efficiency of the high-pressure pump operation, that is to say in particular without an increase in an excess amount of fuel provided by the high-pressure pump.
Im Endeffekt wird dadurch die Aufgabe, die der Erfindung zugrunde liegt, vollkommen gelost.In the end, this completely solves the problem on which the invention is based.
Es ist bevorzugt, dass die Zumesseinheit einen Durchflussquerschnitt aufweist, der die an die Hochdruckpumpe gelieferte Kraftstoffmenge mitbestimmt und der in Abhängigkeit vom Signal des Drucksensors variabelIt is preferred that the metering unit has a flow cross-section which also determines the amount of fuel supplied to the high-pressure pump and which is variable as a function of the signal from the pressure sensor
Durch diese Ausgestaltung wird ein variabler Durchflussquerschnitt zur Androsselung der Hochdruckpumpe verwendet. Ein variabler Durchflussquerschnitt ist, beispielsweise im Vergleich zum digitalen Offnen und/odex Schließen eines konstanten Durchflussquerschnittes, besonders gut für eine gleichmäßige Drosselung geeignet. Grundsätzlich wird die Zumesseinheit in Abhängigkeit vom Fahrverhalten- und Druckkennfeld gesteuert oder geregelt, dass die zur Hochdruckpumpe gelieferte Kraftstoffmenge begrenzt wird. Über den Drucksensor wird der aktuelle Druck im Rail gemessen und mit dem Solldruck vergleichen. Entsprechend dem Vergleichsergebnis wird über die Zumesseinheit die an die Hochdruckpu pe zu liefernde Kraftstoffmenge variiert.With this configuration, a variable flow cross-section is used to throttle the high-pressure pump. A variable flow cross-section is particularly well suited for uniform throttling, for example in comparison to the digital opening and / or closing of a constant flow cross-section. Basically, the metering unit is controlled or regulated depending on the driving behavior and pressure map, that the amount of fuel delivered to the high pressure pump is limited. The current pressure in the rail is measured via the pressure sensor and compared with the target pressure. In accordance with the comparison result, the fuel quantity to be delivered to the high-pressure pump is varied via the metering unit.
Es ist weiter bevorzugt, dass der Durchflussquerschr itt durch den freien Querschnitt einer Öffnung in einer Wandung eines Zylinders bestimmt wird, wobei die Öffnung dur^h einen in dem Zylinder beweglichen Steuerkolben ganz oder teilweise abdeckbar ist, so dass sich der freie Querschnitt mit der Position des Steuerkolbens im Zylinder ändert .It is further preferred that the flow cross-section is determined by the free cross-section of an opening in a wall of a cylinder, the opening being able to be completely or partially covered by a control piston movable in the cylinder, so that the free cross-section coincides with the position of the control piston in the cylinder changes.
Diese Ausgestaltung besitzt den Vorteil, dass sich die Position eines Steuerkolbens, der in einem Zylinder beweglich ist, stetig und genau variieren lasst, so da s sich als Folge eine stetige und genaue Variation des freien Querschnitts, der den Durchflussquerschnitt bestimmt, einstellt .This configuration has the advantage that the position of a control piston, which is movable in a cylinder, can be varied continuously and precisely, so that as a result there is a constant and precise variation of the free cross section which determines the flow cross section.
Es ist weiter bevorzugt, dass der Steuerxolben hohl ausgeführt ist, und eine Öffnung aufweist, so dass der freie Querschnitt durch eine Uberdeckung der Öffnung in der Wandung des Zylinders und der Öffnung in dem Steuerkolben definiert ist.It is further preferred that the control piston is hollow and has an opening so that the free cross section is defined by a covering of the opening in the wall of the cylinder and the opening in the control piston.
Diese Ausgestaltung hat den besonderen Vorteil, dass die Veränderung des Durchflussquerschnitts in Abhängigkeit von der Position des Steuerkolbens durch eine geänderte Große und Form der Öffnung im Steuerkolben beeinflussbar isc. Dies ermöglicht die Realisierung verschiedener Durchflusskennlinien und Durchflussmengen einer Zumesseinheit durch Verwendung verschiedener Steuerkolben. Dadurch wird die Verwendung von Standardkomponen^en einer Zumesseinheit für eine Vielzahl von Hochdruckpumpen und Verbrennungsmotoren möglich, wobei dieThis embodiment has the particular advantage that the change in the flow cross section depending on the position of the control piston can be influenced by a changed size and shape of the opening in the control piston. This enables the realization of different flow characteristics and flow rates of one metering unit by using different control pistons. This makes the use of standard components one Metering unit for a variety of high pressure pumps and internal combustion engines possible, the
Standardzumesseinheit lediglich durch Verwendung eines entsprechenden Steuerkolbens an einen bestimmten Hochdruckpumpentyp und/oder Verbrennungsmotortyp angepasst werden muss .Standard metering unit only has to be adapted to a specific high-pressure pump type and / or internal combustion engine type by using a corresponding control piston.
Es ist weiter bevorzugt, dass das elektromagnetische Stellelement eine Spule und einen in der Spule beweglichen Anker aufweist und dass die Auslenkung des Ankers aus einer Ruhelage proportional zu einem durch die Spule fließenden elektrischen Strom erfolgt.It is further preferred that the electromagnetic actuating element has a coil and an armature movable in the coil and that the armature is deflected from a rest position in proportion to an electrical current flowing through the coil.
Diese Ausgestaltung besitzt den Vorteil, dass sich die Position des Steuerkolbens durch eine technisch leicht beherrschbare Änderung eines Spulenstroms steuern lasst. Anstelle einer reinen Proportionalität kommt selbstverständlich auch eine anders geartete Abhängigkeit der Ankerauslenkung vom Spulenstrom in Frage.This configuration has the advantage that the position of the control piston can be controlled by a technically easily controllable change in a coil current. Instead of a pure proportionality, a different kind of dependence of the armature deflection on the coil current is of course also possible.
Es ist weiter bevorzugt, dass ein Tastverhaltms des durch die Spule fließenden elektrischen Stroms in Abhängigkeit vom Signal des Stromsensors variiert wird.It is further preferred that a duty cycle of the electrical current flowing through the coil is varied depending on the signal of the current sensor.
Diese Ausgestaltung liefert den weiteren besonderen Vorteil, dass der Mittelwert der mit dem Tastverhaltms schwankenden Stromstarke eine mittlere Steuerkolbenposit lon einstellt und dass, bei angepasster Wahl der Tastverhaltnis-Frequenz, die Schwankung der Stromstarke zusätzlich als Dither-Signal wirkt, dass den Steuerkolben n eine schnelle Oszillation geringer Amplitude um se ne Mittellage herum versetzt. Dadurch wird das Entstehen eιn°r Haftreibung verhindert und das Losbrechmoment de Steuerkolbens bei einer gewünschten Veränderung seiner Position verringert. Es ist weiter bevorzugt, dass der Querschnitt im stromlosen Zustand ganz geöffnet ist.This configuration provides the further particular advantage that the mean value of the current intensity fluctuating with the duty cycle sets a medium control piston position and that, with an appropriate choice of the duty cycle frequency, the fluctuation of the current intensity additionally acts as a dither signal that the control piston n has a fast Low-amplitude oscillation offset around its central position. This prevents the occurrence of static friction and reduces the breakaway torque of the control piston in the event of a desired change in its position. It is further preferred that the cross section is completely open in the currentless state.
Diese Ausgestaltung bewirkt vorteilhafterweise, dass der Durchflussquerschnitt im Fehlerfall ganz geöffnet ist, was eine unerwünschte Androsselung der Hochdruckpumpe verhindert und damit die Verfügbarkeit des Common Rail Systems sicherstellt. Eine solche unerwünschte Androsselung konnte sonst dazu fuhren, dass die Fordermenge der Hochdruckpumpe stark beschrankt wird, was zu Leistungsembußen des Verbrennungsmotors oder zu einem Liegenbleiben des Fahrzeugs fuhren konnte.This configuration advantageously has the effect that the flow cross section is fully open in the event of a fault, which prevents undesired throttling of the high-pressure pump and thus ensures the availability of the common rail system. Such undesirable throttling could otherwise result in the demand for the high-pressure pump being severely restricted, which could lead to reduced performance of the internal combustion engine or to the vehicle stopping.
Es ist weiter bevorzugt, dass der flache Verlauf der Kennlinie dadurch erzeugt wird, dass Bewegungen des Steuerkolbens im ungestörten Leerlauf des Verbrennungsmotors zu kleineren Querschnittsanderungen fuhren als beim Betrieb des Verbrennungsmotors außerhalb des Leerlaufs.It is further preferred that the flat course of the characteristic curve is generated in that movements of the control piston in the undisturbed idling of the internal combustion engine lead to smaller cross-sectional changes than when the internal combustion engine is operated outside of idling.
Diese Ausgestaltung besitzt den Vorteil, dass auch bei einer Standardzumesseinheit, bei der sich der Steuerkolben mit dem Anker proportional zu einer Spulenstromstarl- e bewegt, unterschiedlich flache, nicht-lineare und nichtproportionale Kennlinienverlaufe durch die Form der Offnungen im Zylinder und/oder Steuerkolben erzeugen lassen. Auch dadurch wird die Verwendung von Standardkomponenten einer Zumesseinheit zur Verwenclunα bei verschiedenen Hochdruckpumpen und Verbrennungsmotoren ermöglicht .This embodiment has the advantage that even with a standard metering unit in which the control piston moves with the armature proportional to a coil current, differently flat, non-linear and non-proportional characteristic curves can be generated by the shape of the openings in the cylinder and / or control piston , This also enables the use of standard components of a metering unit for use in various high-pressure pumps and internal combustion engines.
Es ist weiter bevorzugt, dass die Konturen der Öffnung im Steuerkolben so festgelegt sind, dass sich ein nicht- lmearer Verlauf der Kennlinie ergibt. Diese Ausgestaltung besitzt den Vorteil, dass sich der Verlauf der Kennlinie durch die Konstruktion des Steuerkolbens, d.h. durch den Verlauf der Konturen der Öffnung im Steuerkolben, festlegen lasst, so αass die entsprechende Konstruktion verschiedener Steuerkolben einer Anpassung einer Standardzumesseinheit an verschiedene Hochdruckpumpen und/oder Verbrennungsmotoren erlaubt.It is further preferred that the contours of the opening in the control piston are fixed in such a way that the characteristic curve is non-linear. This embodiment has the advantage that the course of the characteristic curve can be determined by the design of the control piston, that is to say by the course of the contours of the opening in the control piston, so that the corresponding design of different control pistons is adapted to adapt a standard metering unit to different high-pressure pumps and / or internal combustion engines allowed.
Es ist weiter bevorzugt, dass die Zumesseinheit modular aufgebaut ist, wobei verschiedene Steuerkolben mit dem übrigen Bestandteilen der Zumesseinheit kombiniert werden können und wobei sich die verschiedenen Steuerkolben durch verschiedene Formen und Großen der Öffnung im Sceuerkolben unterscheiden.It is further preferred that the metering unit has a modular structure, different control pistons being able to be combined with the other components of the metering unit, and the different control pistons differing in different shapes and sizes of the opening in the control piston.
Durch diese Ausgestaltung wird die Zahl der Teile, die zur Herstellung von Zumesseinheiten für verschiedene Hochdruckpumpen und/oder Verbrennungsmotoren verwendet werden müssen, verringert, wodurch sich eine vereinfachte und kostengünstigere Fertigung und Vorratshaltung ergibt.This configuration reduces the number of parts that have to be used to manufacture metering units for various high-pressure pumps and / or internal combustion engines, which results in simplified and more cost-effective production and storage.
Weitere Vorteile ergeben sich aus der Beschreibung und den beigefugten Figuren.Further advantages result from the description and the attached figures.
Es versteht sich, dass die vorstehend genannten und die nachstehend noch zu erläuternden Merkmale nicht nur in der jeweils angegebenen Kombination, sondern auch in anderen Kombinationen oder in Allemstellung verwendbar s nd, ohne den Rahmen der vorliegenden Erfindung zu verlassen.It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or in all, without leaving the scope of the present invention.
Zeichnungendrawings
Ausfuhrungsbeispiele der Erfindung sind in der Zeichnung dargestellt und werden in der nachfolgenden Beschreibung naher erläutert. Es zeigen:Exemplary embodiments of the invention are shown in the drawing and are described in the description below explained in more detail. Show it:
Figur 1 das technische Umfeld, in dem die Erfindung ihre Wirkung entfaltet;Figure 1 shows the technical environment in which the invention has its effect;
Figur 2 die Funktion einiger Komponenten aus Figur 1 in der Form eines Ersatzschaltoildes;FIG. 2 shows the function of some components from FIG. 1 in the form of an equivalent switch;
Figur 3 ein Ausfuhrungsbeispiel einer Zumesseinheit 32,FIG. 3 shows an exemplary embodiment of a metering unit 32,
Figur 4 eine Durchflusskennlinie Q ( I ) ;FIG. 4 shows a flow characteristic Q (I);
Figur 5 Kennlinienverlaufe bei einer ersten Ausgestaltung einer Öffnung im Steuerkolben der Zumesseinheit; undFIG. 5 characteristic curves for a first embodiment of an opening in the control piston of the metering unit; and
Figur 6 Verlaufe von Kennlinien bei einer zweiten Ausgestaltung der Öffnung im Steuerkolben.6 curves of characteristic curves in a second embodiment of the opening in the control piston.
Beschreibungdescription
Die Ziffer 10 in der Figur 1 bezeichnet einen Krc-ftstoff- Hochdruckspeicher (Common-Rail), aus dem Injektoren 12 mit unter Einspritzdruck stehendem Kraftstoff versorgt werden. Die Injektoren 12 werden durch elektrische Einspritzimpulsbreiten-Signale, die von einem Steuerger t 14 ausgegeben werden, geöffnet, so dass Kraftstoff in die nicht dargestellten Brennraume eines Verbrennungsmotors eingespritzt wird. Die Einspritzimpulsbreiten werden im Steuergerat 14 unter Ruckgriff auf im Steuergerat 14 abgelegte Steuerprogramme und Daten unter Verwendung verschiedener Eingangssignale gebildet. Wesentliche Eingangssignale sind das Signal eines Fahrerwunschgebers 16 und das Signal eines Drehzahlgebers 18, der die Drehzahl des Verbrennungsmotors angibt. Die Ziffer 20 stehe stellvertretend für weitere Signalgeber, beispielsweise Luftmassengeber, Temperaturgeber,The number 10 in FIG. 1 denotes a high-pressure fuel reservoir (common rail) from which injectors 12 are supplied with fuel under injection pressure. The injectors 12 are opened by electrical injection pulse width signals, which are output by a control device t 14, so that fuel is injected into the combustion chambers (not shown) of an internal combustion engine. The injection pulse widths are formed in the control unit 14 using control programs and data stored in the control unit 14 using various input signals. Essential input signals are the signal from a driver's request transmitter 16 and the signal from a speed transmitter 18, which indicates the speed of the internal combustion engine. The number 20 stands representative of other signal transmitters, for example air mass sensors, temperature sensors,
Fahrgeschwindigkeitsgeber, etc., die im Steuerger t 14 verarbeitet werden.Driving speed sensor, etc., which are processed in the control unit t 14.
Der Kraftstoff wird zunächst aus einem Kraftstoff ank 22 durch eine Zahnradpumpe 24 über einen Vorfilter 26 unα einen Hauptfilter 28 zu einer Hochdruckpumpe 30 geforiert. Üblicherweise ist die Zahnradpumpe 24 an der Hochdruckpumpe 30 angeflanscht, so dass sich beide Pumpen durch eine gemeinsame Welle 31 vom Verbrennungsmotor antreiben lassen. Alternativ zur Zahnradpumpe 24 konnte auch eine Elektrokraftstoffpumpe die Niederdruck-Kraf tstof fforderung vom Tank 22 zur Hochdruckpumpe 30 übernehmen.The fuel is first perforated from a fuel anchor 22 by a gear pump 24 via a prefilter 26 and a main filter 28 to a high pressure pump 30. The gear pump 24 is usually flanged to the high-pressure pump 30, so that both pumps can be driven by the internal combustion engine through a common shaft 31. As an alternative to the gear pump 24, an electric fuel pump could also take over the low-pressure fuel requirement from the tank 22 to the high-pressure pump 30.
Über interne Versorgungskanale fließt der von der Zahnradpumpe 24 mit Niederdruck geforderte Kraftstoff (Druck im Tank 22 plus etwa 3,5 bis 6,0 bar) an die Zumesseinheit 32, die der Hochdruckpumpe 30 stromungsmaßig vorgeschaltet ist. Die Zumesseinheit 32 drosselt die Kraftstoffmenge, die an die Saugseite der Hochdruckpumpe 30 strömt, in Abhängigkeit von einem Ansteuersignal an, das vom Steuergerat 14 bereitgestellt wird. Die
Figure imgf000015_0001
i n die Hochdruckpumpe 30 gelieferte Kraftstoffmenge wird von der Hochdruckseite der Hochdruckpumpe 30 parallel an den Kraftstoff-Hochdruckspeicher 10 und an ein Druckregelventil 34 geliefert, das ebenfalls vom Steuergerat 14 gesteuert/geregelt wird.The fuel required by the gear pump 24 with low pressure (pressure in the tank 22 plus approximately 3.5 to 6.0 bar) flows via internal supply channels to the metering unit 32, which is connected upstream of the high-pressure pump 30 in terms of flow. The metering unit 32 throttles the amount of fuel that flows to the suction side of the high-pressure pump 30 as a function of a control signal that is provided by the control unit 14. The
Figure imgf000015_0001
The amount of fuel supplied to the high-pressure pump 30 is delivered in parallel from the high-pressure side of the high-pressure pump 30 to the high-pressure fuel reservoir 10 and to a pressure regulating valve 34, which is also controlled / regulated by the control device 14.
Bei geöffnetem Druckregelventil 34 fließt der von der Hochdruckpumpe 30 geforderte Kraftstoff über das Druckregelventil 34 zum Tank 22 zurück. Darüber hinaus weisen die Injektoren eine Leckagemenge auf, die ebenfalls an den Tank zurückgeführt werden uss. Be geschlossenem Druckregelventil 34 fließt der von der Hochdruckpumpe 30 geforderte Kraftstoff dagegen in den Kraftstoff- Hochdruckspeicher 10 und erhöht den Kraftstoffdruck innerhalb des Kraftstoff-Hochdruckspeichers 10. Dieser Druck wird von einem Drucksensor 36 registriert, der ein entsprechendes Signal an das Steuergerat 14 liefert. Wie bereits eingangs erwähnt, steuert das Steuergerat 14 in der Folge die Zumesseinheit 32 und/oder das Druckregelventil 34 so an, dass sich im Kraftstoff-Hochdruckspeicher 10 der gewünschte Kraftstoffdruck einstellt.When the pressure control valve 34 is open, the fuel required by the high pressure pump 30 flows back to the tank 22 via the pressure control valve 34. In addition, the injectors have a leakage amount, which is also returned to the tank. When the pressure control valve 34 is closed, it flows from the high pressure pump 30 required fuel, however, in the fuel high-pressure accumulator 10 and increases the fuel pressure within the fuel high-pressure accumulator 10. This pressure is registered by a pressure sensor 36, which delivers a corresponding signal to the control unit 14. As already mentioned at the beginning, the control device 14 subsequently controls the metering unit 32 and / or the pressure control valve 34 in such a way that the desired fuel pressure is set in the high-pressure fuel reservoir 10.
Figur 2 verdeutlicht durch die sequentielle Anordnung der Zahnradpumpe 24, die allgemeiner als Niederdruckpumpe 24 bezeichnet werden kann, der Zumesseinheit 32 und der Hochdruckpumpe 30, zunächst den Kraftstofffluss zwischen Hauptfilter 28 und Kraftstoff-Hochdruckspeicher 10. Wie bereits beschrieben, drosselt die Zumesseinheit 32 den von der Niederdruckpumpe 24 bereitgestellten Kraftstoffström an der Saugseite der Hochdruckpumpe 30. In der Darstellung der Figur 2 ist die Hochdruckpumpe 30 eine Radialkolbenpu pe mit drei Pumpenelementen 38, die jeweils einen Pumpenkolben 42 aufweisen, der in einem Pumpzylinder 40 beweglich geführt und durch eine exzentrische Antriebswelle 31 betätigt wird.Figure 2 illustrates the sequential arrangement of the gear pump 24, which can be more generally referred to as a low-pressure pump 24, the metering unit 32 and the high-pressure pump 30, the fuel flow between the main filter 28 and the high-pressure fuel reservoir 10. As already described, the metering unit 32 throttles that of the low-pressure pump 24 provided fuel flow on the suction side of the high-pressure pump 30. In the illustration in FIG. 2, the high-pressure pump 30 is a radial piston pump with three pump elements 38, each having a pump piston 42, which is movably guided in a pump cylinder 40 and by an eccentric drive shaft 31 is operated.
Durch periodisches Betätigen der Pumpenkolben 40 saugt die Hochdruckpumpe 30 Kraftstoff von ihrer Saugseite 50 über Niederdruckventile 44 in Pumpenzylinder 42 und fordert den Kraftstoff unter hohem Druck über Hochdruckventile 46 an die Hochdruckseite 54 der Hochdruckpumpe 30 und anschließend an den Kraftstoff-Hochdruckspeicher 10 und das Druckregelventil 34. Figur 2 zeigt noch eine sog. Null- Förderdrossel 52, über die Kraftstoff von der Saugseite 50, der nicht von den Pumpenelementen 38 der Hochdruckpumpe 30 angesaugt wird, zum Eingang der Niederdruckpumpe 24 oder auch zum Tank 22 zurückströmen kann. Be starker Androsselung durch die Zumesseinheit 32 kann es passieren, dass der Kraftstoffdruck auf der Saugseite 50 der Hochdruckpumpe 30 durch über die Null-Forderdrossel 52 abfließenden Kraftstoff unter den Offnungsdruc. der Niederdruckventile 44 fallt. Die Niederdruc entile 44 offnen dann nicht, was zur Folge hat, dass die Pumpenelemente 38 keinen Kraftstoff von der Saugseite 50 der Hochdruckpumpe 30 ansaugen und daher auch keinen Kraftstoff unter Hochdruck an die Hochdruckseite 54 der Hochdruckforderpumpe 30 liefern.By periodically actuating the pump pistons 40, the high-pressure pump 30 sucks fuel from its suction side 50 via low-pressure valves 44 into the pump cylinder 42 and requests the fuel under high pressure via high-pressure valves 46 to the high-pressure side 54 of the high-pressure pump 30 and then to the high-pressure fuel reservoir 10 and the pressure control valve 34 2 also shows a so-called zero delivery throttle 52, via which fuel from the suction side 50, which is not drawn in by the pump elements 38 of the high-pressure pump 30, can flow back to the inlet of the low-pressure pump 24 or to the tank 22. In the event of severe throttling by the metering unit 32, it can happen that the fuel pressure on the suction side 50 of the high-pressure pump 30 is caused by fuel flowing through the zero-throttle 52 below the opening pressure. the low pressure valve 44 falls. The low-pressure valves 44 then do not open, which means that the pump elements 38 do not draw any fuel from the suction side 50 of the high-pressure pump 30 and therefore do not deliver any fuel under high pressure to the high-pressure side 54 of the high-pressure pump 30.
Wie bereits weiter oben kurz skizziert, kann dies zu einem Absinken des Kraftstoffdruckes in Kraftstoff- Hochdruckspeicher 10 fuhren, der über den Drucksensor 36 und das Steuergerat 14 zu einer gegenläufigen Öffnung jer Zumesseinheit 32 fuhrt. Bei vergleichsweise steiler Kennlinie der Zumesseinheit 32 bewirkt dies einen schnellen Anstieg der von der Hochdruckpumpe 30 geforderten Kraftstoffmenge, was einen Anstieg des Drucks im Kraftstoff-Hochdruckspeicher 10 bewirkt. Die daraus bex ungunstig zusammenwirkenden Systemtoleranzen resultierende periodische Druckschwingung im Kraftstoff-Hochdruckspeicner wird durch eine im kritischen Forderbereich flach verlaufende Kennlinie der Zumesseinheit 32 verhindert. Der kritische Forderbereich ist insbesondere der Leerlaut des Verbrennungsmotors, weil in diesem Betriebszustand des Verbrennungsmotors der Kraftstoffbedarf sehr gering ist, was zu einer starken Androsselung durch die Zumessemhex t 32 mit den beschriebenen Wirkungen fuhren kann.As already briefly outlined above, this can lead to a drop in the fuel pressure in the high-pressure fuel reservoir 10, which leads to an opposite opening of the metering unit 32 via the pressure sensor 36 and the control device 14. With a comparatively steep characteristic curve of metering unit 32, this causes a rapid increase in the amount of fuel required by high-pressure pump 30, which causes an increase in pressure in high-pressure fuel accumulator 10. The resulting periodic pressure oscillation in the high-pressure fuel storage tank, which results in unfavorably interacting system tolerances, is prevented by a characteristic curve of the metering unit 32 that runs flat in the critical delivery area. The critical demand range is, in particular, the idle sound of the internal combustion engine, because in this operating state of the internal combustion engine the fuel requirement is very low, which can lead to severe throttling by the metering hex 32 with the effects described.
Figur 3 zeigt ein Ausfuhrungsbeispiel einer Zumesseinheit 32. Die Zumesseinheit 32 weist ein Kunststoffgehause 56 auf, m das elektrische Anschlüsse 58 eingegossen sind Das Kunststoffgehause 56 ist mit einem magnetischen Topf 64 verbunden, in dem eine Spule 62 durch eine Halterung 63 gehalten wird. In der Spule 62 ist ein Anker 60 beweglich geführt. Der Anker 60 erstreckt sich durch einen magnetischen Kern 66, der mit dem magnetischen Topf 64 verbunden ist. Der magnetische Kern 66 weist einen hohlen Zylinder 69 auf, in dem ein hohler Steuerkolben 68 beweglich gefuhrt ist.FIG. 3 shows an exemplary embodiment of a metering unit 32. The metering unit 32 has a plastic housing 56, in which electrical connections 58 are cast in. The plastic housing 56 has a magnetic pot 64 connected in which a coil 62 is held by a holder 63. An armature 60 is movably guided in the coil 62. The armature 60 extends through a magnetic core 66 which is connected to the magnetic pot 64. The magnetic core 66 has a hollow cylinder 69, in which a hollow control piston 68 is movably guided.
Der Steuerkolben 68 wird durch den Anker 60 gegen die RUckstellkraft einer Feder 70 betätigt. Der Zylinder 69 im magnetischen Kern 66 weist Öffnungen 74 auf, über die eine Ringnut 76 in der Mantelflache des Zylinders 69 mit Kraftstoff von der Niederdruckpumpe 24 versorgt wird. Der Kraftstoff in der Ringnut 76 umspult den Steuerkolben 68 und fließt, wenn sich eine Öffnung im Steuerkolben 68 wenigstens teilweise mit der Ringnut 76 oder den Offnungen 74 in der Mantelflache des Zylinders 69 deckt, durch die Öffnung 72 und das Innere des hohlen Steuerkolbens 68 durch den nach unten offenen Zylinder 69 zur Hochdruckpumpe 30.The control piston 68 is actuated by the armature 60 against the restoring force of a spring 70. The cylinder 69 in the magnetic core 66 has openings 74 through which an annular groove 76 in the lateral surface of the cylinder 69 is supplied with fuel from the low-pressure pump 24. The fuel in the annular groove 76 coils around the control piston 68 and, if an opening in the control piston 68 at least partially coincides with the annular groove 76 or the openings 74 in the lateral surface of the cylinder 69, flows through the opening 72 and the interior of the hollow control piston 68 the downwardly open cylinder 69 to the high pressure pump 30.
Figur 4 zeigt schematisch eine mögliche Kennlinie des Durchflusses Q über dem Spulenstrom I der Zumesseinheit 32. Diese Kennlinie entspricht, wie sich unmittelbar aus der Darstellung der Figur 4 ergibt, einer stromlos offenen Zumesseinheit 32, wie sie bevorzugt verwendet wird.FIG. 4 schematically shows a possible characteristic of the flow Q over the coil current I of the metering unit 32. As is immediately apparent from the illustration in FIG. 4, this characteristic corresponds to a normally open metering unit 32, as is preferably used.
Figur 5 zeigt rechts oben eine erste Ausgestaltung des Steuerkolbens 68 mit resultierenden Kennlinien 82, 84. Der nicht lineare, gekrümmte Verlauf der Kennlinien 82, 84 ergibt sich als Folge der trapez- oder dreieckformigen Ausgestaltung der Öffnung 72 im Steuerkolben 68.FIG. 5 shows a first configuration of the control piston 68 with the resulting characteristic curves 82, 84 in the top right corner. The non-linear, curved profile of the characteristic curves 82, 84 results as a result of the trapezoidal or triangular configuration of the opening 72 in the control piston 68.
Im Gegensatz dazu zeigt Figur 6 stuckweise lineare .'erlaufe von Kennlinien 78, 80, wie sie sich bei der Verwendung des in der Figur 6 rechts oben schematisch im Schnitt dargestellten Steuerkolbens 68 ergeben. Der Steuerkolben 68 nach der Figur 6 zeichnet sich durch eine Scnlit zgeometπe aus, bei der ein oberer schmaler Schlitz stufenförmig xp einen unteren breiteren Schlitz übergeht. Der obere schmale Schlitz ist dem flacher verlaufenden Keil der Kennlinie der Figur 6, also dem gemeinsamen rechts verlaufenden Kennlinienast in der Figur 6, zugeordnet. Der größere Offnungsquerschnitt (breiterer Schlitz) entspricnt den linken Asten der Kennlinien 78, 80, die vergleichsweise steil verlaufen.In contrast to this, FIG. 6 shows linear curves of characteristic curves 78, 80 in pieces, as is shown schematically in section when using the top right in FIG. 6 shown control piston 68 result. The control piston 68 according to FIG. 6 is distinguished by a slit zgeometπe, in which an upper narrow slit merges stepwise x p a lower wider slit. The upper narrow slot is assigned to the flatter wedge of the characteristic curve in FIG. 6, that is to say the common right-hand characteristic curve branch in FIG. 6. The larger opening cross-section (wider slot) corresponds to the left branches of the characteristic curves 78, 80, which run comparatively steeply.
Die unterschiedliche Steigung der beiden Kennlinien 78, 80 entspricht unterschiedlich breiten unteren Schlitzen der Öffnung 72 im Steuerkolben 68. Beiden Kennlinien 78, 80 ist der rechts verlaufende flache Kennlinienteil gemeinsam. Ansonsten unterscheiden sich die Kennlinien 78, 80 durch die maximale Durchflussmenge, die bei der Kennlinie 80 wesentlich hoher liegt, als bei der Kennlinie 78. Die Kennlinie 80 ist daher einem Einspritzsystem zugeoidnet, das für einen größeren Kraftstoffbedarf ausgelegt ist . Analoge Betrachtungen gelten für die beiden Kennlinien 82, 84 in der Figur 5. The different slope of the two characteristic curves 78, 80 corresponds to lower slits of the opening 72 in the control piston 68 of different widths. Both characteristic curves 78, 80 have the flat characteristic curve part running to the right in common. Otherwise, the characteristic curves 78, 80 differ in the maximum flow rate, which is much higher for the characteristic curve 80 than for the characteristic curve 78. The characteristic curve 80 is therefore associated with an injection system which is designed for a greater fuel requirement. Analogous considerations apply to the two characteristic curves 82, 84 in FIG. 5.

Claims

Ansprüche Expectations
1. Vorrichtung zur Aufrechterhaltung eines Solldruckes m einem Kraftstoff-Hochdruckspeicher (10) eines Speichereinspritzsystems eines 'Verbrennungsmotors , mit einem Drucksensor (36), einer Hochdruckpumpe (30) und einer Zumesseinheit (32), die eine Durchflusskennlinie (78, 80; 82, 84) aufweist, wobei1. Device for maintaining a target pressure in a high-pressure fuel reservoir (10) of a storage injection system of an ' internal combustion engine, with a pressure sensor (36), a high-pressure pump (30) and a metering unit (32), which have a flow characteristic (78, 80; 82, 84), where
- der Drucksensor (36) ein Signal bereitstellt, das den Druck im Kraftstoff-Hochdruckspeicher (10) angibt, und- The pressure sensor (36) provides a signal indicating the pressure in the high-pressure fuel reservoir (10), and
- die Zumesseinheit (32) die von der Hochdruckpumpe (30) an den Kraftstoff-Hochdruckspeicher (10) gelieferte Kraftstoffmenge in Abhängigkeit vom Signal des Drucksensors- The metering unit (32) the amount of fuel supplied by the high pressure pump (30) to the high pressure fuel reservoir (10) as a function of the signal from the pressure sensor
(36) begrenzt, indem die Zumesseinheit (32) die Kraftstoffmenge beschrankt, die an die Hochdruckpumpe (30) geliefert wird,(36) limited by the metering unit (32) limiting the amount of fuel that is supplied to the high pressure pump (30),
dadurch gekennzeichnet, dasscharacterized in that
- die Durchflusskennlinie (78, 80; 82, 84) bei einem Durchfluss, der dem Leerlaufbedarf des Verbrennungsmotors entspricht, einen so flachen Verlauf aufweist, dass im ungestörten Leerlaufbetrieb des Verbrennungsmotors auftretende Änderungen des Drucksensorsignals nicht zu einer Unterbrechung der von der Hochdruckpumoe (30) gelieferten Kraftstoffmenge fuhren- The flow characteristic (78, 80; 82, 84) with a flow rate that corresponds to the idling requirement of the internal combustion engine has such a flat profile that changes in the pressure sensor signal that occur during undisturbed idling operation of the internal combustion engine do not increase an interruption in the amount of fuel supplied by the high pressure pump (30)
2. Vorrichtung zur Zumessung von Kraftstoff zu einer Hochdruckpumpe (30) zur Aufrechterhaltung eines Solldruckes in einem Kraftstoff-Hochdruckspeicher (10) eines Speichereinspritzsystems eines Verbrennungsmotors, mit einem Drucksensor (36), wobei2. Device for metering fuel to a high-pressure pump (30) for maintaining a target pressure in a high-pressure fuel reservoir (10) of a storage injection system of an internal combustion engine, with a pressure sensor (36), wherein
- die Vorrichtung eine Zumesseinheit (32) bildet, die eine Durch lusskennlinie (78, 80; 82, 84) aufweist,- The device forms a metering unit (32) which has a flow characteristic (78, 80; 82, 84),
- der Drucksensor (36) ein Signal bereitstellt, das den Druck im Kraftstoff-Hochdruckspeicher (10) angibt, und- The pressure sensor (36) provides a signal indicating the pressure in the high-pressure fuel reservoir (10), and
- die Zumesseinheit (32) die von der Hochdruckpumpe (30) an den Kraftstoff-Hochdruckspeicher (10) gelieferte Kraftstoffmenge in Abhängigkeit vom Signal des Drucksensors (36) begrenzt, indem sie die Kraftstoffmenge bescnraπ.f, die an die Hochdruckpumpe (30) geliefert wird,- The metering unit (32) limits the amount of fuel delivered by the high-pressure pump (30) to the high-pressure fuel reservoir (10) as a function of the signal from the pressure sensor (36) by bescnraπ.f the amount of fuel supplied to the high-pressure pump (30) becomes,
dadurch gekennzeichnet, dasscharacterized in that
- die Durchflusskennlinie (78, 80; 82, 84) bei einem Durchfluss, der dem Leerlaufbedarf des Verbrennungsmotors entspricht, einen so flachen Verlauf aufweist, dass im ungestörten Leerlaufbetrieb des Verbrennungsmotors auftretende Änderungen des Drucksensorsignals nicht zu einer Unterbrechung der von der Hochdruckpumpe (30) gelieferten Kraftstoffmenge fuhren.- The flow characteristic (78, 80; 82, 84) at a flow rate that corresponds to the idling requirement of the internal combustion engine has such a flat course that changes in the pressure sensor signal that occur during undisturbed idling operation of the internal combustion engine do not lead to an interruption of the pressure pump (30) deliver the amount of fuel supplied.
3. Vorrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Zumesseinheit (32) einen Durchflussquerschnitt aufweist, der die an die Hochdruckpumpe (30) gelieferte Kraftstoffmenge mitbes- unrund der in Abhängigkeit vom Signal des Drucksensors (36) variabel ist. 3. Device according to claim 1 or 2, characterized in that the metering unit (32) has a flow cross-section, which is the amount of fuel supplied to the high-pressure pump (30) mitbes- non-circular depending on the signal of the pressure sensor (36).
4. Vorrichtung nach Anspruch 3, dadurch gekennzeichnet, dass der Durchflussquerschnitt durch den freien Querschnitt einer Öffnung (74, 76) in einer Wandung eines Z l--nc.ers (69) bestimmt wird, wobei die Öffnung (74, 76) durch eiren in dem Zylinder (69) beweglichen Steuerkolben (68) ganz oder teilweise abdeckbar ist, so dass sich der freie Querschnitt mit der Position des Steuerkolbens (68) im Zylinder (69) ändert.4. The device according to claim 3, characterized in that the flow cross-section through the free cross-section of an opening (74, 76) in a wall of a Z l - nc.ers (69) is determined, wherein the opening (74, 76) through Eiren in the cylinder (69) movable control piston (68) can be completely or partially covered, so that the free cross section changes with the position of the control piston (68) in the cylinder (69).
5. Vorrichtung nach Anspruch 4, dadurch gekennzeichnet, dass der Steuerkolben (68) hohl ausgeführt ist und eine Öffnung (72) aufweist, so dass der freie Querschnitt durch eine Uberdeckung der Öffnung (74, 76) in der Wandung des Zylinders (69) und der Öffnung (72) in dem Steuerkolben (68) definiert ist.5. The device according to claim 4, characterized in that the control piston (68) is hollow and has an opening (72) so that the free cross section through a covering of the opening (74, 76) in the wall of the cylinder (69) and the opening (72) is defined in the control piston (68).
6. Vorrichtung nach Anspruch 4 oder 5, dadurch gekennzeichnet, dass die Zumesseinheit (32) ein elektromagnetisches Stellelement (60, 62) aufweist, mit dem die Position des Steuerkolbens (68) einstellbar ist.6. The device according to claim 4 or 5, characterized in that the metering unit (32) has an electromagnetic actuator (60, 62) with which the position of the control piston (68) is adjustable.
7. Vorrichtung nach Anspruch 5, dadurch gekennzeichnet, dass das elektromagnetische Stellelement (60, 62) eine Spule (62) und einen in der Spule (62) beweglichen Anker (60) aufweist, und dass die Auslenkung des Ankers (60) aus einer Ruhelage proportional zu einem durch die Spule (62) fließenden elektrischen Strom erfolgt.7. The device according to claim 5, characterized in that the electromagnetic actuating element (60, 62) has a coil (62) and an armature (60) movable in the coil (62), and in that the deflection of the armature (60) from a Rest position is proportional to an electrical current flowing through the coil (62).
8. Vorrichtung nach Anspruch 6, dadurch gekennzeichnet, dass ein Tastverhaltms des durch die Spule (62) rließenαen elektrischen Stroms in Abhängigkeit vom Signal des Drucksensors (36) variiert wird.8. The device according to claim 6, characterized in that a tactile behavior of the electrical current through the coil (62) is varied as a function of the signal from the pressure sensor (36).
9. Vorrichtung nach Anspruch 7, dadurch gexennzeicnnet , dass der Durchflussquerschnitt im stromlosen Zustand ganz geöffnet ist. 9. The device according to claim 7, characterized gexennzeicnnet that the flow cross section is completely open in the de-energized state.
10. Vorrichtung nach einem der Ansprüche 3 - 5, dadurch gekennzeichnet, dass der flache Verlauf der Kennlinie (78, 80; 82, 84) dadurch erzeugt wird, dass Bewegungen des Steuerkolbens (68) im ungestörten Leerlauf des Verbrennungsmotors zu kleineren Querschnittsanαerungen fuhren als beim Betrieb des Verbrennungsmotors außerhalb des Leerlaufs.10. Device according to one of claims 3 - 5, characterized in that the flat course of the characteristic curve (78, 80; 82, 84) is generated in that movements of the control piston (68) in the undisturbed idling of the internal combustion engine lead to smaller cross-sectional changes than when the internal combustion engine is operating outside of idling.
11. Vorrichtung nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass die Konturen der Öffnung (72) im Steuerkolben (68) so festgelegt sind, dass sich ein nichtlinearer Verlauf der Kennlinie (78, 80; 82, 84) ergibt .11. The device according to one of claims 1 to 6, characterized in that the contours of the opening (72) in the control piston (68) are fixed so that there is a non-linear course of the characteristic curve (78, 80; 82, 84).
12. Vorrichtung nach Anspruch 5, dadurch gekennzeichnet, dass die Zumesseinheit (32) modular aufgebaut ist, wobei verschiedene Steuerkolben (68) mit den übrigen Bestandteilen der Zumesseinheit (32) kombiniert werden können, und wobei sich die verschiedenen Steuerkolben (68) durch verschiedene Formen und Großen der Öffnung (72) m Steuerkolben (68) unterscheiden. 12. The device according to claim 5, characterized in that the metering unit (32) is of modular construction, wherein different control pistons (68) can be combined with the other components of the metering unit (32), and wherein the different control pistons (68) are different Differentiate the shapes and sizes of the opening (72) from the control piston (68).
PCT/DE2003/002515 2002-12-06 2003-07-25 Device for maintaining a set pressure in the high pressure fuel reservoir of a common-rail injection system WO2004053325A1 (en)

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DE2002157134 DE10257134A1 (en) 2002-12-06 2002-12-06 Automatic pressure control system for high-pressure fuel reservoir for common rail injection system for internal combustion engine, incorporates pressure sensor and fuel metering device

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WO2016034402A1 (en) * 2014-09-01 2016-03-10 Robert Bosch Gmbh Proportional valve that can be actuated electromagnetically

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DE602004014265D1 (en) * 2004-06-30 2008-07-17 Fiat Ricerche Injection system for internal combustion engine
DE102009029219A1 (en) 2009-09-04 2011-03-10 Robert Bosch Gmbh Fuel high pressure storage device for use in fuel injection system, particularly for diesel internal combustion engines, comprises storage element for fuel, in which borehole is formed in longitudinal axis
IT201800007039A1 (en) * 2018-07-09 2020-01-09 PUMPING GROUP TO FEED FUEL, PREFERABLY DIESEL, TO AN INTERNAL COMBUSTION ENGINE

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US20020000217A1 (en) * 2000-06-26 2002-01-03 Tohru Takahashi Flow amount control device

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Publication number Priority date Publication date Assignee Title
EP1918573A3 (en) * 2006-11-02 2009-09-02 Mitsubishi Heavy Industries, Ltd. Fuel injection apparatus for engines
WO2016034402A1 (en) * 2014-09-01 2016-03-10 Robert Bosch Gmbh Proportional valve that can be actuated electromagnetically

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