EP0800621A1 - Valve for dosed feeding of vaporised fuel from a fuel tank of an internal combustion engine - Google Patents

Valve for dosed feeding of vaporised fuel from a fuel tank of an internal combustion engine

Info

Publication number
EP0800621A1
EP0800621A1 EP96918613A EP96918613A EP0800621A1 EP 0800621 A1 EP0800621 A1 EP 0800621A1 EP 96918613 A EP96918613 A EP 96918613A EP 96918613 A EP96918613 A EP 96918613A EP 0800621 A1 EP0800621 A1 EP 0800621A1
Authority
EP
European Patent Office
Prior art keywords
valve
armature
electromagnet
valve according
fuel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP96918613A
Other languages
German (de)
French (fr)
Other versions
EP0800621B1 (en
Inventor
Wolfgang Schulz
Georg Mallebrein
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
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 EP0800621A1 publication Critical patent/EP0800621A1/en
Application granted granted Critical
Publication of EP0800621B1 publication Critical patent/EP0800621B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

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
    • F02M25/00—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
    • F02M25/08—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding fuel vapours drawn from engine fuel reservoir
    • 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
    • F02M25/00—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
    • F02M25/08—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding fuel vapours drawn from engine fuel reservoir
    • F02M25/0836—Arrangement of valves controlling the admission of fuel vapour to an engine, e.g. valve being disposed between fuel tank or absorption canister and intake manifold
    • 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
    • F02M25/00—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
    • F02M25/08—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding fuel vapours drawn from engine fuel reservoir
    • F02M2025/0845—Electromagnetic valves

Definitions

  • the invention is based on a valve for the metered introduction of fuel vapor volatilized from a fuel tank of an internal combustion engine into an intake pipe of the internal combustion engine according to the preamble of claim 1.
  • a valve for the metered introduction of fuel vapor volatilized from a fuel tank of an internal combustion engine into an intake pipe of the internal combustion engine according to the preamble of claim 1.
  • Such a valve is already known (EP-PS 0 528 849)
  • the fuel vapor via a Inlet nozzle is supplied in order to discharge it in a metered manner into the intake pipe via an outlet nozzle provided on the valve.
  • the inflow nozzle of the valve is connected, for example, via a hose line to an adsorption filter, which temporarily stores the fuel vapor evaporated from the fuel tank.
  • the valve is designed to be electromagnetically actuated and for this purpose has a magnetic armature which can be axially displaced by the magnetic forces of an electromagnet against the force of a valve spring.
  • a magnetic armature which can be axially displaced by the magnetic forces of an electromagnet against the force of a valve spring.
  • an end region of the armature designed as a valve closing member is pressed against a valve seat by means of the valve spring in order to interrupt a flow connection from the inlet connection to the outlet connection.
  • the armature moves against the force of the valve spring and lifts off with its end region designed as a valve closing member from the valve seat, one
  • the metering opening on the outflow nozzle is opened so that a certain fuel vapor volume can flow from the inflow pipe via the outflow pipe into the intake pipe.
  • the solenoid of the valve is controlled by means of a so-called pulse-width modulated signal, which is composed of a pulse train of an electric current which flows through the excitation coil of the electromagnet at a constant frequency.
  • the pulse duration of the individual current pulses is increased or decreased by means of control electronics in order to obtain a continuously variable attraction force of the electromagnet on the armature.
  • a certain axial position of the armature is set, in which it remains, in order to be replaced by one of the axial position of the
  • Valve closing member of the armature-dependent throttling of the flow at the metering opening to deliver a certain volume of fuel vapor via the metering opening into the outflow nozzle depends on the pulse duration of the individual current pulses and is determined by the so-called duty cycle.
  • the duty cycle indicates the quotient of the pulse duration to the pulse interval (period) of the individual pulses. Due to frictional effects and spring forces, it only takes place after a certain one
  • Duty cycle which is also referred to as an opening duty cycle, a lifting of the armature from its valve seat.
  • Hysteresis effects have the consequence that the opening duty cycle can change with each renewed activation, so that an exact metering is the smallest
  • the described, continuously operating valve emits an essentially linearly increasing fuel vapor flow with increasing pulse duty factor.
  • the linear nature of the valve described makes it difficult to meter the smallest fuel vapor volume with a relatively small duty cycle.
  • attempts are therefore made to compensate for this disadvantage by means of a second, vacuum-actuated valve.
  • the second vacuum-actuated valve is arranged parallel to the first electromagnetically actuable valve, which opens when a certain vacuum is reached in the intake pipe in order to introduce more fuel vapor into the intake pipe.
  • such a system consisting of two valves is complex.
  • the specified valve combination requires a long switch-off time to interrupt the fuel supply, so that a sensitive
  • valve according to the invention with the characterizing features of claim 1 has the advantage, an excellent small amount metering and a simple structure.
  • the measures listed in the subclaims allow advantageous developments of the valve specified in claim 1.
  • a pressure compensation connection formed in the valve which makes it possible to measure the fuel vapor flow emitted by the valve independently of the negative pressure prevailing in the intake pipe.
  • an intended compensation of the temperature dependency of the excitation coil of the electromagnet which makes it possible to dispense with a complex current-controlled output stage and to replace it with a control in which voltage pulses with a preferably relatively high frequency are supplied to the excitation coil in order to make a particularly sensitive metering of the fuel vapor volume.
  • Another special advantage is the special design of the metering opening in the valve, which gives the valve an exponential opening characteristic in order to minimize the absolute error in the small quantity range. The exponential opening characteristic also counteracts errors due to hysteresis effects, so that a further improvement in the small-quantity meterability of the valve is possible.
  • FIG. 1 shows a longitudinal section of a valve designed according to the invention
  • FIG. 2 shows a first section along a line II-II in FIG. 1 according to a first according to the invention
  • Figure 3 shows a second section along a line III-III in Figure 1 according to a second embodiment of the invention
  • Figure 4 is a diagram showing the opening characteristics of the valve designed according to the invention (course B) compared to known valves (course A).
  • valve 1 shown in longitudinal section in FIG. 1 is used for the metered introduction of a fuel tank 3, not shown, in particular mixture-compressing, spark-ignited internal combustion engine evaporated fuel vapor into an intake pipe 4 of the internal combustion engine.
  • Valve 1 is part of a fuel evaporation retention system of the internal combustion engine, the mode of operation of which can be found, for example, on the pages Bosch and Technical Documentation, Motor Management Motronic, Second Edition, August 1993, on pages 48 and 49.
  • the valve 1 has, for example, a valve housing consisting of three parts, which is composed of a cylindrical basic housing 6, a housing cover 7 which can be placed on the basic housing 6 and a lower housing part 8.
  • the cylindrical basic housing 6, the housing cover 7 and the lower housing part 8 are preferably made of plastic, for example using plastic injection molding technology.
  • the lower housing part 8 has an inlet connection 10 and an outlet connection 11.
  • the inflow nozzle 10 serves to connect the valve 1, for example via a first hose line 14, to the fuel tank 3 or, as shown in FIG. 1, to an adsorption filter 15 connected to the fuel tank 3.
  • the adsorption filter 15 is provided with a storage medium for fuel vapor , in particular filled with activated carbon, and is used for the intermediate storage of fuel vapor volatilized from the fuel tank 3.
  • the outflow connector 11 extends, for example, in the axial direction from the lower housing part 8 along a longitudinal axis 17 of the valve 1 and is provided for connecting a second hose line 18.
  • the second hose line 18 opens, for example, downstream of a throttle valve 19 rotatably accommodated in the intake pipe 4 into the intake pipe 4.
  • the inflow nozzle 10 extends, for example, transversely to the longitudinal axis 17 of the valve 1 and projects radially from the lower housing part 8.
  • an electromagnet 22 is accommodated in a magnet housing 26, which has a cylindrical excitation coil 23 and a magnetic core 37.
  • the magnet housing 26 is sleeve-shaped and carries in its interior the excitation coil 23, which is wound on a coil carrier 27 made, for example, of plastic.
  • the excitation coil 23 surrounds a preferably metallic armature 25 of the valve 1 which can be attracted by magnetic forces in order to move it in the energized state of the excitation coil 23 against the force of a valve spring 50.
  • the armature 25 is axially displaceably mounted in a guide sleeve 24 accommodated in the basic housing 6.
  • the coil carrier 27 is accommodated at a radial distance from an outer surface 39 of the smaller-diameter guide sleeve 24 in the interior of the basic housing 6 and extends radially to an inner wall 29 of the magnet housing 26.
  • the radial distance from the coil carrier 27 to the outer surface 39 of the guide sleeve 24 prevents jamming of the armature 25 due to thermal expansion, for example the excitation coil 23.
  • the coil carrier 27 lies axially against an annular extension 28 of the guide sleeve 24.
  • the shoulder 28 of the guide sleeve 24 also extends radially as far as the inner wall 29 of the magnet housing 26.
  • a contact disk 31 is also accommodated, which is at a radial distance from an outer surface 33 of the armature 25 is arranged.
  • the armature 25 has a recess 36 on its end 32 facing the housing cover 7, said recess being cylindrical, for example, and at least partially surrounding the sleeve-shaped magnetic core 37.
  • the magnetic core 37 can be designed to be axially displaceable.
  • the magnetic core 37 has, for example, an external thread section 38 which engages in an internal thread 40 which is provided in a magnetic base 35 covering the sleeve-shaped magnetic housing 26 in order to correspondingly axially shift the magnetic core 37 by rotating the magnetic core 37, so that an adjustable armature stop for the anchor 25 is present.
  • the armature 25 is hollow-cylindrical and has a through-opening 42 which extends in the axial direction from the recess 36 at the end 32 of the armature 25 shown at the top in FIG. 1 to its end 34 located in the lower housing part 8.
  • a circumferential one that radially enlarges the passage opening 42
  • Heel 45 designed to receive the valve spring 50 between the heel 45 and a recess 46 provided in the sleeve-shaped magnetic core 37.
  • the valve spring 50 is supported on the one hand in the recess 45 on the magnetic core 37 and on the other hand on the shoulder 45 in the through opening
  • valve spring 50 By means of the valve spring 50, the armature 25 in the de-energized state of the excitation coil 23 is pressed tightly with its end 34 against an annular valve seat 54 covered by an annular sealing ring 53, so that a flow connection 74 between the inflow connection piece 10 and
  • Outflow nozzle 11 is closed.
  • the valve seat 54 is provided on an end 55 of the outflow connector 11 located in the interior of the lower housing part 8 and, as is shown in the half of the valve 1 lying on the left of the longitudinal axis 17, can be tightly closed by the armature 25.
  • the sealing ring 53 consists of an elastic material, for example rubber.
  • the magnetic armature 25 is affected by the magnetic forces of the
  • Electromagnets 22 are attracted to the magnetic core 37 differently and occupies each axial intermediate position and as End position, as shown in the right half of the longitudinal axis 17 of the valve 1, its maximum open position, in which the annular bottom surface 48 of the recess 36 of the armature 25 bears against the annular surface 49 of the magnetic core 37.
  • the outer surface 33 of the armature opens at the circumference of a metering opening 56 which runs parallel to the longitudinal axis 17 at an end 51 of the inflow nozzle 10 located in the basic housing 6, so that, as shown in FIG 1 marked arrow 57, fuel vapor passes from the inflow nozzle 10 through the metering opening 56 into a space 79 delimited between the valve seat 54 and an end face 73 of the armature 25, in order to then continue to flow into the outflow nozzle 11 via the valve seat 54.
  • a smaller part of the fuel vapor passes into the passage opening 42 of the armature 25, from there into the recess 46 of the magnetic core 37 and from the recess 46 via an opening 60 in the magnetic core 37 to get into a space 62 which is sealed off from the surroundings by an inner wall 64 of the housing cover 7, the magnetic core 37 and the magnetic base 35 of the magnet housing 26.
  • a pressure compensation connection 70 which is provided in the basic housing 6 and in the lower housing part 8, for example in the form of a bore, and which opens into the outflow connection 11 downstream of the valve seat 54.
  • the partial flow of the fuel vapor identified by the arrows 58, 59 and 61 in FIG. 1 flows around the valve seat 54.
  • the main stream of the fuel vapor flowing in the direction of arrow 57 from the inflow neck 10 to the outflow neck 11 mixes with the partial stream flowing in the direction of the arrows 58, 59 and 61 downstream of the valve seat 54 and then from the outflow neck 11 to Example to get into the intake pipe 4 via the second hose line 18.
  • Dosing opening 56 is more or less released from its outer surface 33, so that the fuel vapor flow passing from the inlet nozzle 10 into the outlet nozzle 11 is appropriately metered.
  • the stroke of the armature 25 working against the valve spring 50 is determined by the strength of the magnetic field of the electromagnet 22.
  • an electronic control unit 80 is provided which is electrically connected to the electromagnet 22 via an electrical line 81 and via a plug connection 82 integrally molded on the housing cover 7.
  • the electronic control device 80 transmits to the electromagnet 22 a drive pulse sequence of an electrical voltage with a relatively high frequency of, for example, 100 Hertz.
  • the control pulse sequence is emitted by the electronic control unit 80 with a duty cycle that can be changed by the control unit 80.
  • the pulse duty factor indicates, for example, the quotient of the pulse duration to the pulse interval (period duration) of the successive pulses.
  • Such control is known to the person skilled in the art as so-called pulse-width modulation.
  • the excitation coil 23 preferably has an excitation winding which has an almost constant resistance value regardless of the temperature influences of the
  • Has valve 1 Such a temperature-compensated excitation winding can be constructed, for example, from two windings which are made of different materials, the resistance values of which are chosen such that the temperature dependence of the resistance value of both is compensated
  • a winding of the excitation coil 23 can consist of a material which has a positive temperature coefficient (PTC thermistor) and the other winding consists of a material that has a negative temperature coefficient (NTC thermistor).
  • PTC thermistor positive temperature coefficient
  • NTC thermistor negative temperature coefficient
  • an output stage can therefore be used which supplies the electromagnet 22 with a voltage pulse sequence, preferably at a relatively high frequency.
  • a voltage pulse sequence can be implemented technically in a particularly simple manner, for example in the form of a transistor circuit which the
  • DC voltage source of a motor vehicle for example that of a starter battery, is used in order to switch back and forth between two predetermined values, for example 12 volts and 0 volts.
  • a voltage pulse sequence causes an average current in the excitation coil 23, which induces a magnetic field of a certain strength in order to move the armature 25 away from the valve seat 54 against the force of the valve spring 50 and to bring it into a specific axial position.
  • the axial end position of the armature 25 depends on the applied duty cycle of the voltage pulse train. If no voltage is applied to the excitation coil 23 or no current flows in the excitation coil 23, the armature 25 is removed from the
  • Valve spring 50 pressed against the valve seat 54.
  • the armature 25 rests with its outer surface 33 on the sealing ring 53 and covers the metering opening 56 of the inflow connector 10, so that a flow connection from the inflow connector 10 to the outflow connector 11 is interrupted.
  • the metering opening 56 is designed in the form of an aperture, the opening cross section of which is designed such that the valve 1 is given an exponential opening characteristic.
  • Figure 2 a sectional view along a line II-II in Figure 1, a first embodiment of the invention.
  • the metering opening 56 has a V-shape with a cross-sectional area which is delimited by two cross-sectional borders 75, 76 which converge towards one another in the direction of the valve seat 54 and a circular arc section 77.
  • a small gap can also remain between the cross-sectional borders 75, 76 in the region of their smallest distance from one another.
  • the funnel-shaped design of the cross-sectional borders 75, 76 of the metering opening 56 results in that with increasing piston stroke H of the armature 25 an increasingly larger cross-sectional area of the metering opening 56, limited by the cross-sectional borders 75, 76 and the end face 73 of the anchor 25, is released, so that the volume of the fuel vapor flowing through the metering opening 56 can increase accordingly.
  • Range of larger duty cycles causes a slight change in the duty cycle T compared to a valve with a linear opening characteristic (curve A), a relatively large change in the volume flow, so that rapid control of high volume flows is possible.
  • the metering opening 56 can also be designed in such a way that the cross-sectional boundaries 75, 76 have a curve which, based on that in FIG 3 drawn in coordinate axes x, y of a Cartesian coordinate system with an x axis parallel to the longitudinal axis 17, of an exponential function, in particular a natural exponential function, can be described. They have
  • the maximum stroke H of the armature 25 can be set such that the armature 25 with its end face 73 at maximum stroke, at most end points 85, 86 of the
  • Cross-sectional borders 75 and 76 are reached so that the armature 25 only exposes a cross-sectional area of the metering opening 56 with exponential cross-sectional borders 75, 76.
  • the pressure compensation connection 70 provided in the valve housing 6, 7, 8 also enables the underpressure of the intake pipe 4 in the raised state of the armature 25 both on the end face 73 of the armature 25 and on the opposite bottom surface 48 of the
  • Recess 36 on armature 25 prevails.
  • the end face 73 and the bottom face 48 of the armature 25 preferably have approximately an equal area of attack, whereby a pressure equalization or force equalization on the armature 25 is effected at different intake manifold pressures, so that the metering of the fuel vapor volume is independent of the negative pressure prevailing in the intake manifold 4.
  • the flow paths 10, 11, 42, 62, 66, 70 of the fuel vapor in the valve 1 from the environment, in particular with respect to an interior space 89 of the electromagnet 22 that is subjected to atmospheric pressure.
  • Sealing is carried out, for example, by means of a seal 88 which is designed in the form of a sealing sleeve which, for example, lies tightly against the inside of the outer surface 33 of the armature 25 in the lower housing part 8 and is clamped radially on the outside between the base housing 6 and the lower housing part 8.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Magnetically Actuated Valves (AREA)
  • Feeding And Controlling Fuel (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

Known tank ventilation valves which continuously dose the stream of vaporised fuel have a linear opening characteristic which does not enable precise dosing of very small amounts of vaporised fuel. The invention relates to a valve (1) which is provided for dosed feeding of vaporised fuel from a fuel tank (3) of an internal combustion engine into an inlet manifold (4) of the internal combustion engine. The said valve has a valve housing (8) which has a intake pipe (10) for connection to a ventilation pipe of the fuel tank (3) or to an adsorption filter (15), connected downstream thereof for the vaporised fuel, and has a discharge pipe (11) for connection to the inlet manifold (4). Said valve also has an armature (25) which is movable by an electromagnet (22), is inside the valve housing (6) and, when pressed against a valve seat (54) by a valve spring (50) when the electromagnet (22) is not provided with current, said armature closes a dosing port (56) of a flow connection (74) from the intake pipe (10) to the outlet pipe (11) and opens said port to a varying extent when the electromagnet (22) is provided with current. The dosing port (56) has a V-shaped cross-section for improved dosing. The present valve is suitable for feeding into the inlet manifold of an internal combustion engine, vaporised fuel from a fuel tank of a mixture-compressing, spark-ignition internal combustion engine.

Description

Ventil zum dosierten Einleiten von aus einem Brennstofftank einer Brennkraftmaschine verflüchtigtem BrennstoffdampfValve for the metered introduction of fuel vapor volatilized from a fuel tank of an internal combustion engine
Stand der TechnikState of the art
Die Erfindung geht aus von einem Ventil zum dosierten Einleiten von aus einem Brennstofftank einer Brennkraftmaschine verflüchtigtem Brennstoffdampf in ein Ansaugrohr der Brennkraftmaschine nach der Gattung des Anspruchs 1. Es ist schon ein derartiges Ventil bekannt (EP- PS 0 528 849) , dem Brennstoffdampf über einen Zuströmstutzen zugeführt wird, um diesen in dosierter Weise über einen am Ventil vorgesehenen Abströmstutzen in das Ansaugrohr abzugeben. Der Zuströmstutzen des Ventils ist zum Beispiel über eine Schlauchleitung mit einem Adsorptionsfilter verbunden, der den aus dem Brennstofftank verflüchtigten Brennstoffdampf zwischenspeichert. Das Ventil ist elektromagnetisch betätigbar ausgebildet und hat hierzu einen magnetischen Anker, der von den magnetischen Kräften eines Elektromagneten gegen die Kraft einer Ventilfeder axial verschiebbar ist. Im stromlosen Zustand des Elektromagneten wird ein als Ventilschließglied ausgebildeter Endbereich des Ankers mittels der Ventilfeder an einen Ventilsitz gepreßt, um eine Strömungsverbindung vom Zuströmstutzen zum Abströmstutzen zu unterbrechen. Im bestromten Zustand bewegt sich der Anker gegen die Kraft der Ventilfeder und hebt mit seinem als Ventilschließglied ausgebildeten Endbereich vom Ventilsitz ab, wobei eineThe invention is based on a valve for the metered introduction of fuel vapor volatilized from a fuel tank of an internal combustion engine into an intake pipe of the internal combustion engine according to the preamble of claim 1. Such a valve is already known (EP-PS 0 528 849), the fuel vapor via a Inlet nozzle is supplied in order to discharge it in a metered manner into the intake pipe via an outlet nozzle provided on the valve. The inflow nozzle of the valve is connected, for example, via a hose line to an adsorption filter, which temporarily stores the fuel vapor evaporated from the fuel tank. The valve is designed to be electromagnetically actuated and for this purpose has a magnetic armature which can be axially displaced by the magnetic forces of an electromagnet against the force of a valve spring. In the de-energized state of the electromagnet, an end region of the armature designed as a valve closing member is pressed against a valve seat by means of the valve spring in order to interrupt a flow connection from the inlet connection to the outlet connection. In the energized state, the armature moves against the force of the valve spring and lifts off with its end region designed as a valve closing member from the valve seat, one
Zumeßöffnung am Abströmstutzen geöffnet wird, so daß ein bestimmtes Brennstoffdampfvolumen vom Zuströmstutzen über den Abströmstutzen in das Ansaugrohr strömen kann.The metering opening on the outflow nozzle is opened so that a certain fuel vapor volume can flow from the inflow pipe via the outflow pipe into the intake pipe.
Die Ansteuerung des Elektromagneten des Ventils erfolgt mittels eines sogenannten puls-breiten modulierten Signals, das sich aus einer Impulsfolge eines elektrischen Stroms zusammensetzt, der mit konstanter Frequenz die Erregerspule des Elektromagneten durchströmt. Zu Ansteuerungszwecken wird die Impulsdauer der einzelnen Stromimpulse mittels einer Steuerelektronik vergrößert oder verkleinert, um damit eine kontinuierlich veränderbare Anziehungskraft des Elektromagneten auf den Anker zu erhalten. Dabei stellt sich abhängig von der Impulsdauer der einzelnen Impulse eine bestimmte axiale Lage des Ankers ein, in welcher er verharrt, um durch eine von der axialen Lage desThe solenoid of the valve is controlled by means of a so-called pulse-width modulated signal, which is composed of a pulse train of an electric current which flows through the excitation coil of the electromagnet at a constant frequency. For control purposes, the pulse duration of the individual current pulses is increased or decreased by means of control electronics in order to obtain a continuously variable attraction force of the electromagnet on the armature. In this case, depending on the pulse duration of the individual pulses, a certain axial position of the armature is set, in which it remains, in order to be replaced by one of the axial position of the
Ventilschließgliedes des Ankers abhängige Drosselung der Strömung an der Zumeßöffnung ein bestimmtes Brennstoffdampfvolumen über die Zumeßöffnung in den Abströmstutzen abzugeben. Die magnetische Kraft des Elektromagneten hängt dabei von der Impulsdauer der einzelnen Stromimpulse ab und wird durch das sogenannte Tastverhältnis bestimmt. Das Tastverhältnis gibt den Quotienten der Impulsdauer zum Impulsabstand (Periodendauer) der einzelnen Impulse an. Aufgrund von Reibungseffekten und Federkräften erfolgt erst ab einem bestimmtenValve closing member of the armature-dependent throttling of the flow at the metering opening to deliver a certain volume of fuel vapor via the metering opening into the outflow nozzle. The magnetic force of the electromagnet depends on the pulse duration of the individual current pulses and is determined by the so-called duty cycle. The duty cycle indicates the quotient of the pulse duration to the pulse interval (period) of the individual pulses. Due to frictional effects and spring forces, it only takes place after a certain one
Tastverhältnis, das auch als Öffnungstastverhältnis bezeichnet wird, ein Abheben des Ankers von seinem Ventilsitz. Hysterese-Effekte haben dabei zur Folge, daß das Öffnungstastverhältnis sich bei jeder erneuten Ansteuerung verändern kann, so daß eine genaue Zumessung kleinsterDuty cycle, which is also referred to as an opening duty cycle, a lifting of the armature from its valve seat. Hysteresis effects have the consequence that the opening duty cycle can change with each renewed activation, so that an exact metering is the smallest
Brennstoffdampfvolumen mit einem derartigen Ventil bisher nicht möglich ist. Des weiteren ist der Wicklungswiderstand der Erregerspule des Elektromagneten temperaturabhängig, so daß auch das Öffnungstastverhältnis von der Temperatur abhängt. Daher ist es erforderlich, den Elektromagneten mittels einer stromgeregelten Endstufe anzusteuern, die ein puls-breiten moduliertes Stromsignal bereitstellt. Eine derartige stromgeregelte Endstufe ist jedoch bei einem mit einer Gleichspannungsquelle üblicherweise ausgestatteten Fahrzeug bekanntermaßen relativ aufwendig zu realisieren.Fuel vapor volume with such a valve has so far not been possible. Furthermore, the winding resistance of the excitation coil of the electromagnet is temperature-dependent, so that the opening duty ratio also depends on the temperature. It is therefore necessary to control the electromagnet by means of a current-controlled output stage, which provides a pulse-width modulated current signal. A Such a current-controlled output stage, however, is known to be relatively difficult to implement in a vehicle that is usually equipped with a DC voltage source.
Das beschriebene, stetig arbeitende Ventil gibt mit wachsendem Tastverhältnis einen im wesentlichen linear zunehmenden Brennstoffdampfström ab. Der lineare Charakter des beschriebenen Ventils erschwert jedoch die Zumessung kleinster Brennstoffdampfvolumen bei relativ kleinem Tastverhältnis. Im angegebenen Stand der Technik wird daher versucht, diesen Nachteil mittels eines zweiten, unterdruckbetätigten Ventils auszugleichen. Das zweite unterdruckbetätigte Ventil ist parallel zum ersten elektromagnetisch betätigbaren Ventil angeordnet, das beim Erreichen eines bestimmten Unterdrucks im Ansaugrohr öffnet, um vermehrt Brennstoffdampf in das Ansaugrohr einzuleiten. Ein derartiges System bestehend aus zwei Ventilen ist jedoch aufwendig. Darüber hinaus benötigt die angegebene Ventilkombination eine lange Abschaltzeit, um die Brennstoffzufuhr zu unterbrechen, so daß eine feinfühligeThe described, continuously operating valve emits an essentially linearly increasing fuel vapor flow with increasing pulse duty factor. However, the linear nature of the valve described makes it difficult to meter the smallest fuel vapor volume with a relatively small duty cycle. In the stated prior art, attempts are therefore made to compensate for this disadvantage by means of a second, vacuum-actuated valve. The second vacuum-actuated valve is arranged parallel to the first electromagnetically actuable valve, which opens when a certain vacuum is reached in the intake pipe in order to introduce more fuel vapor into the intake pipe. However, such a system consisting of two valves is complex. In addition, the specified valve combination requires a long switch-off time to interrupt the fuel supply, so that a sensitive
Anpassung des Volumens des je Zeiteinheit in das Ansaugrohr eingespeisten Brennstoffdampfes in verschiedenen Betriebszuständen der Brennkraftmaschine kaum möglich ist.Adaptation of the volume of the fuel vapor fed into the intake pipe per unit of time in various operating states of the internal combustion engine is hardly possible.
Vorteile der ErfindungAdvantages of the invention
Das erfindungsgemäße Ventil mit den kennzeichnenden Merkmalen des Anspruchs 1 hat demgegenüber den Vorteil, einer hervorragenden Kleinmengendosierbarkeit sowie eines einfachen Aufbaus.The valve according to the invention with the characterizing features of claim 1 has the advantage, an excellent small amount metering and a simple structure.
Durch die in den Unteransprüchen aufgeführten Maßnahmen sind vorteilhafte Weiterbildungen des im Anspruch 1 angegebenen Ventils möglich. Von besonderem Vorteil ist eine im Ventil ausgebildete Druckausgleichsverbindung, die es ermöglicht, den vom Ventil abgegebenen Brennstoffdampfström unabhängig von im Ansaugrohr herrschenden Unterdruck zuzumessen. Von Vorteil ist weiterhin eine vorgesehene Kompensation der Temperaturabhängigkeit der Erregerspule des Elektromagneten, die es ermöglicht, auf eine aufwendige stromgeregelte Endstufe zu verzichten und diese durch eine Ansteuerung zu ersetzen, bei welcher Spannungsimpulse mit vorzugsweise relativ hoher Frequenz der Erregerspule zugeführt werden, um eine besonders feinfühlige Zumessung des Brennstoffdampfvolumens zu ermöglichen. Von besonderem Vorteil ist außerdem die besondere Gestaltung der Zumeßöffnung im Ventil, welche dem Ventil eine exponentielle Öffnungscharakteristik verleiht, um den absoluten Fehler im Kleinmengenbereich zu minimieren. Die exponentielle Öffnungscharakteristik wirkt außerdem Fehlern aufgrund von Hysterese-Effekten entgegen, so daß eine weitere Verbesserung der Kleinmengendosierbarkeit des Ventils möglich ist.The measures listed in the subclaims allow advantageous developments of the valve specified in claim 1. Of particular advantage is a pressure compensation connection formed in the valve, which makes it possible to measure the fuel vapor flow emitted by the valve independently of the negative pressure prevailing in the intake pipe. Of Another advantage is an intended compensation of the temperature dependency of the excitation coil of the electromagnet, which makes it possible to dispense with a complex current-controlled output stage and to replace it with a control in which voltage pulses with a preferably relatively high frequency are supplied to the excitation coil in order to make a particularly sensitive metering of the fuel vapor volume. Another special advantage is the special design of the metering opening in the valve, which gives the valve an exponential opening characteristic in order to minimize the absolute error in the small quantity range. The exponential opening characteristic also counteracts errors due to hysteresis effects, so that a further improvement in the small-quantity meterability of the valve is possible.
Zeichnungdrawing
Ausführungsbeispiele der Erfindung sind in der Zeichnung vereinfacht dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 einen Längsschnitt eines erfindungsgemäß ausgebildeten Ventils, Figur 2 einen ersten Schnitt entlang einer Linie II-II in Figur 1 gemäß einem ersten erfindungsgemäßenEmbodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description. FIG. 1 shows a longitudinal section of a valve designed according to the invention, FIG. 2 shows a first section along a line II-II in FIG. 1 according to a first according to the invention
Ausführungsbeispiel, Figur 3 einen zweiten Schnitt entlang einer Linie III-III in Figur 1 gemäß einem zweiten erfindungsgemäßen Ausführungsbeispiel, Figur 4 ein Diagramm, das die Öffnungscharakteristik des erfindungsgemäß ausgebildeten Ventils (Verlauf B) im Vergleich zu bekannten Ventilen (Verlauf A) zeigt.Embodiment, Figure 3 shows a second section along a line III-III in Figure 1 according to a second embodiment of the invention, Figure 4 is a diagram showing the opening characteristics of the valve designed according to the invention (course B) compared to known valves (course A).
Beschreibung der AusführungsbeispieleDescription of the embodiments
Das in Figur 1 im Längsschnitt dargestellte Ventil 1 dient zum dosierten Einleiten von aus einem Brennstofftank 3 einer nicht näher dargestellten, insbesondere gemischverdichtenden, fremdgezündeten Brennkraftmaschine verflüchtigtem Brennstoffdampf in ein Ansaugrohr 4 der Brennkraftmaschine. Das Ventil 1 ist Teil eines Brennstoffverdunstungs-Rückhaltesystems der Brennkraftmaschine, dessen Funktionsweise beispielsweise der Druckschrift Bosch Technische Unterrichtung, Motormanagement Motronic, zweite Ausgabe, August 1993, auf Seiten 48 und 49 entnehmbar ist.The valve 1 shown in longitudinal section in FIG. 1 is used for the metered introduction of a fuel tank 3, not shown, in particular mixture-compressing, spark-ignited internal combustion engine evaporated fuel vapor into an intake pipe 4 of the internal combustion engine. Valve 1 is part of a fuel evaporation retention system of the internal combustion engine, the mode of operation of which can be found, for example, on the pages Bosch and Technical Documentation, Motor Management Motronic, Second Edition, August 1993, on pages 48 and 49.
Das Ventil 1 hat ein zum Beispiel aus drei Teilen bestehendes Ventilgehäuse, das sich aus einem zylindrischen Grundgehäuse 6, einem auf das Grundgehäuse 6 aufsetzbaren Gehäusedeckel 7 und einem unteren Gehäuseteil 8 zusammensetzt. Das zylindrische Grundgehäuse 6, der Gehäusedeckel 7 und das untere Gehäuseteil 8 sind vorzugsweise aus Kunststoff, zum Beispiel in Kunststoffspritzgußtechnik, hergestellt. Das untere Gehäuseteil 8 weist einen Zustromstutzen 10 und einen Abströmstutzen 11 auf. Der Zuströmstutzen 10 dient zum Anschließen des Ventils 1, zum Beispiel über eine erste Schlauchleitung 14, an den Brennstofftank 3 oder, wie in Figur 1 dargestellt ist, an einen mit dem Brennstofftank 3 verbundenen Adsorptionsfilter 15. Der Adsorptionsfilter 15 ist mit einem Speichermedium für Brennstoffdampf, insbesondere mit Aktivkohle, gefüllt und dient zur Zwischenspeicherung von aus dem Brennstofftank 3 verflüchtigtem Brennstoffdampf. Der Abströmstutzen 11 erstreckt sich zum Beispiel in axialer Richtung vom unteren Gehäuseteil 8 entlang einer Längsachse 17 des Ventils 1 und ist zum Anschluß einer zweiten Schlauchleitung 18 vorgesehen. Die zweite Schlauchleitung 18 mündet beispielsweise stromabwärts einer drehbar in das Ansaugrohr 4 untergebrachten Drosselklappe 19 in das Ansaugrohr 4. Der Zuströmstutzen 10 erstreckt sich zum Beispiel quer zur Längsachse 17 des Ventils 1 und steht radial vom unteren Gehäuseteil 8 ab. Im Inneren des Grundgehäuses 6 ist in einem Magnetgehäuse 26 ein Elektromagnet 22 untergebracht, der eine zylindrische Erregerspule 23 und einem Magnetkern 37 besitzt. Das Magnetgehäuse 26 ist hülsenförmig ausgebildet und trägt in seinem Inneren die Erregerspule 23, die auf einem zum Beispiel aus Kunststoff bestehenden Spulenträger 27 aufgewickelt ist. Die Erregerspule 23 umgibt einen von magnetischen Kräften anziehbaren, vorzugsweise metallenen Anker 25 des Ventils 1, um diesen im bestromten Zustand der Erregerspule 23 gegen die Kraft einer Ventilfeder 50 zu bewegen. Der Anker 25 ist hierzu in einer im Grundgehäuse 6 untergebrachten Führungshülse 24 axial verschiebbar gelagert. Der Spulenträger 27 ist mit radialem Abstand zu einer Außenfläche 39 der durchmesserkleineren Führungshülse 24 im Inneren des Grundgehäuses 6 untergebracht und erstreckt sich radial bis zu einer Innenwandung 29 des Magnetgehäuses 26. Der radiale Abstand des Spulenträgers 27 zur Außenfläche 39 der Führungshülse 24 verhindert dabei ein Verklemmen des Ankers 25 aufgrund von Wärmeausdehnungen, zum Beispiel der Erregerspule 23. Der Spulenträger 27 liegt axial an einem ringförmigen Ansatz 28 der Führungshülse 24 an. Der Ansatz 28 der Führungshülse 24 erstreckt sich radial ebenfalls bis zur Innenwandung 29 des Magnetgehäuses 26. Zwischen dem Ansatz 28 der Führungshülse 24 und einem radial umlaufenden Steg 30 des Grundgehäuses 6 ist zum Beispiel noch eine Anlagescheibe 31 untergebracht, die mit radialem Abstand zu einer Außenfläche 33 des Ankers 25 angeordnet ist.The valve 1 has, for example, a valve housing consisting of three parts, which is composed of a cylindrical basic housing 6, a housing cover 7 which can be placed on the basic housing 6 and a lower housing part 8. The cylindrical basic housing 6, the housing cover 7 and the lower housing part 8 are preferably made of plastic, for example using plastic injection molding technology. The lower housing part 8 has an inlet connection 10 and an outlet connection 11. The inflow nozzle 10 serves to connect the valve 1, for example via a first hose line 14, to the fuel tank 3 or, as shown in FIG. 1, to an adsorption filter 15 connected to the fuel tank 3. The adsorption filter 15 is provided with a storage medium for fuel vapor , in particular filled with activated carbon, and is used for the intermediate storage of fuel vapor volatilized from the fuel tank 3. The outflow connector 11 extends, for example, in the axial direction from the lower housing part 8 along a longitudinal axis 17 of the valve 1 and is provided for connecting a second hose line 18. The second hose line 18 opens, for example, downstream of a throttle valve 19 rotatably accommodated in the intake pipe 4 into the intake pipe 4. The inflow nozzle 10 extends, for example, transversely to the longitudinal axis 17 of the valve 1 and projects radially from the lower housing part 8. In the interior of the basic housing 6, an electromagnet 22 is accommodated in a magnet housing 26, which has a cylindrical excitation coil 23 and a magnetic core 37. The magnet housing 26 is sleeve-shaped and carries in its interior the excitation coil 23, which is wound on a coil carrier 27 made, for example, of plastic. The excitation coil 23 surrounds a preferably metallic armature 25 of the valve 1 which can be attracted by magnetic forces in order to move it in the energized state of the excitation coil 23 against the force of a valve spring 50. For this purpose, the armature 25 is axially displaceably mounted in a guide sleeve 24 accommodated in the basic housing 6. The coil carrier 27 is accommodated at a radial distance from an outer surface 39 of the smaller-diameter guide sleeve 24 in the interior of the basic housing 6 and extends radially to an inner wall 29 of the magnet housing 26. The radial distance from the coil carrier 27 to the outer surface 39 of the guide sleeve 24 prevents jamming of the armature 25 due to thermal expansion, for example the excitation coil 23. The coil carrier 27 lies axially against an annular extension 28 of the guide sleeve 24. The shoulder 28 of the guide sleeve 24 also extends radially as far as the inner wall 29 of the magnet housing 26. Between the shoulder 28 of the guide sleeve 24 and a radially circumferential web 30 of the basic housing 6, for example, a contact disk 31 is also accommodated, which is at a radial distance from an outer surface 33 of the armature 25 is arranged.
Zur Begrenzung der maximalen Auslenkung des Ankers 25 hat dieser an seinem dem Gehäusedeckel 7 zugewandten Ende 32 eine Ausnehmung 36, die zum Beispiel zylindrisch ausgebildet ist und den hülsenförmig ausgebildeten Magnetkern 37 zumindest teilweise umgibt. Bei maximaler Auslenkung des Ankers 25 schlägt dieser in der Ausnehmung 36 mit seiner ringförmigen Bodenfläche 48 an einer Ringfläche 49 des Magnetkerns 37 an. Um eine Einstellung des maximalen Hubs des Ankers 25 zu ermöglichen, kann der Magnetkern 37 axial verschiebbar ausgebildet sein. Der Magnetkern 37 hat hierzu beispielsweise einen Außengewindeabschnitt 38, der in ein Innengewinde 40 eingreift, das in einem das hülsenformige Magnetgehäuse 26 abdeckenden Magnetboden 35 vorgesehen ist, um durch Drehen des Magnetkerns 37 den Magnetkern 37 entsprechend axial zu verschieben, so daß ein einstellbarer Ankeranschlag für den Anker 25 vorhanden ist.In order to limit the maximum deflection of the armature 25, the armature 25 has a recess 36 on its end 32 facing the housing cover 7, said recess being cylindrical, for example, and at least partially surrounding the sleeve-shaped magnetic core 37. When the armature 25 is deflected to the maximum extent, it rests in the recess 36 with its annular bottom surface 48 on an annular surface 49 of the magnetic core 37. To set the maximum stroke of the armature 25, the magnetic core 37 can be designed to be axially displaceable. For this purpose, the magnetic core 37 has, for example, an external thread section 38 which engages in an internal thread 40 which is provided in a magnetic base 35 covering the sleeve-shaped magnetic housing 26 in order to correspondingly axially shift the magnetic core 37 by rotating the magnetic core 37, so that an adjustable armature stop for the anchor 25 is present.
Der Anker 25 ist hohlzylindrisch ausgebildet und hat eine Durchgangsöffnung 42, die sich in axialer Richtung von der Ausnehmung 36 am in Figur 1 oben dargestellten Ende 32 des Ankers 25 bis zu seinem im unteren Gehäuseteil 8 gelegenen Ende 34 erstreckt. In der Durchgangsδffnung 42 ist ein die Durchgangsöffnung 42 radial vergrößernder, umlaufenderThe armature 25 is hollow-cylindrical and has a through-opening 42 which extends in the axial direction from the recess 36 at the end 32 of the armature 25 shown at the top in FIG. 1 to its end 34 located in the lower housing part 8. In the passage opening 42 there is a circumferential one that radially enlarges the passage opening 42
Absatz 45 ausgebildet, um zwischen dem Absatz 45 und einer im hülsenförmigen Magnetkern 37 vorgesehenen Ausnehmung 46 die Ventilfeder 50 aufzunehmen. Die Ventilfeder 50 stützt sich dabei einerseits in der Ausnehmung 45 am Magnetkern 37 und andererseits an dem Absatz 45 in der DurchgangsöffnungHeel 45 designed to receive the valve spring 50 between the heel 45 and a recess 46 provided in the sleeve-shaped magnetic core 37. The valve spring 50 is supported on the one hand in the recess 45 on the magnetic core 37 and on the other hand on the shoulder 45 in the through opening
42 am Anker 25 ab. Mittels der Ventilfeder 50 wird der Anker 25 im stromlosen Zustand der Erregerspule 23 mit seinem Ende 34 an einen von einem ringförmigen Dichtring 53 bedeckten ringförmigen Ventilsitz 54 dicht angedrückt, so daß eine Strömungsverbindung 74 zwischen Zuströmstutzen 10 und42 on anchor 25. By means of the valve spring 50, the armature 25 in the de-energized state of the excitation coil 23 is pressed tightly with its end 34 against an annular valve seat 54 covered by an annular sealing ring 53, so that a flow connection 74 between the inflow connection piece 10 and
Abströmstutzen 11 geschlossen wird. Der Ventilsitz 54 ist an einem im Inneren des unteren Gehäuseteils 8 gelegenen Ende 55 des Abströmstutzens 11 vorgesehen und, wie in der links der Längsachse 17 liegenden Hälfte des Ventils 1 dargestellt ist, von dem Anker 25 dicht verschließbar. Der Dichtring 53 besteht hierzu aus einem elastischen Material, beispielsweise Gummi.Outflow nozzle 11 is closed. The valve seat 54 is provided on an end 55 of the outflow connector 11 located in the interior of the lower housing part 8 and, as is shown in the half of the valve 1 lying on the left of the longitudinal axis 17, can be tightly closed by the armature 25. For this purpose, the sealing ring 53 consists of an elastic material, for example rubber.
Im bestromten Zustand der Erregerspule 23 wird der magnetische Anker 25 von den magnetischen Kräften desIn the energized state of the excitation coil 23, the magnetic armature 25 is affected by the magnetic forces of the
Elektromagneten 22 unterschiedlich zum Magnetkern 37 hin angezogen und nimmt jede axiale Zwischenstellung ein und als Endstellung, wie in der rechts der Längsachse 17 liegenden Hälfte des Ventils 1 dargestellt ist, seine maximale Offenstellung ein, bei der die ringförmige Bodenfläche 48 der Ausnehmung 36 des Ankers 25 an der Ringfläche 49 des Magnetkerns 37 anliegt. Bei der Aufwärtsbewegung des Ankers 25 zum Magnetkern 37 hin öffnet dieser mit seiner Außenfläche 33 am Umfang eine Zumeßöffnung 56, die parallel zur Längsachse 17 verlaufend an einem im Grundgehäuse 6 liegenden Ende 51 des Zustromstutzens 10 vorgesehen ist, so daß, wie durch einen in Figur 1 eingezeichneten Pfeil 57 gekennzeichnet ist, Brennstoffdampf vom Zuströmstutzen 10 durch die Zumeßöffnung 56 hindurch in einen zwischen dem Ventilsitz 54 und einer Stirnfläche 73 des Ankers 25 begrenzten Raum 79 gelangt, um anschließend über den Ventilsitz 54 in den Abstromstutzen 11 weiterzuströmen.Electromagnets 22 are attracted to the magnetic core 37 differently and occupies each axial intermediate position and as End position, as shown in the right half of the longitudinal axis 17 of the valve 1, its maximum open position, in which the annular bottom surface 48 of the recess 36 of the armature 25 bears against the annular surface 49 of the magnetic core 37. During the upward movement of the armature 25 towards the magnetic core 37, the outer surface 33 of the armature opens at the circumference of a metering opening 56 which runs parallel to the longitudinal axis 17 at an end 51 of the inflow nozzle 10 located in the basic housing 6, so that, as shown in FIG 1 marked arrow 57, fuel vapor passes from the inflow nozzle 10 through the metering opening 56 into a space 79 delimited between the valve seat 54 and an end face 73 of the armature 25, in order to then continue to flow into the outflow nozzle 11 via the valve seat 54.
Wie durch einen in Figur 1 eingezeichneten Pfeil 58 gekennzeichnet ist, gelangt dabei ein kleinerer Teil des Brennstoffdampfes in die Durchgangsδffnung 42 des Ankers 25, um von dieser in die Ausnehmung 46 des Magnetkerns 37 und von der Ausnehmung 46 über eine im Magnetkern 37 weiterführende Öffnung 60 in einen Raum 62 zu gelangen, der von einer Innenwand 64 des Gehäusedeckels 7, dem Magnetkern 37 und dem Magnetboden 35 des Magnetgehäuses 26 dicht von der Umgebung abgeschlossen ist. Über eine im Gehäusedeckel 7 vorgesehene Öffnung 66 gelangt der Brennstoffdampf dann weiter vom Raum 62 in eine Druckausgleichsverbindung 70, die im Grundgehäuse 6 und im unteren Gehäuseteil 8 zum Beispiel in Form einer Bohrung vorgesehen ist und die stromabwärts des Ventilsitzes 54 in den Abstromstutzen 11 mündet. Der in Figur 1 durch die Pfeile 58, 59 und 61 gekennzeichnete Teilstrom des Brennstoffdampfes strömt dabei um den Ventilsitz 54 herum. Der in Richtung des Pfeils 57 vom Zuströmstutzen 10 zum Abströmstutzen 11 strömende Hauptstrom des Brennstoffdampfes vermischt sich mit dem in Richtung der Pfeile 58, 59 und 61 strömenden Teilstrom stromabwärts des Ventilsitzes 54, um danach vom Abströmstutzen 11 zum Beispiel über die zweite Schlauchleitung 18 in das Ansaugrohr 4 zu gelangen.As indicated by an arrow 58 shown in FIG. 1, a smaller part of the fuel vapor passes into the passage opening 42 of the armature 25, from there into the recess 46 of the magnetic core 37 and from the recess 46 via an opening 60 in the magnetic core 37 to get into a space 62 which is sealed off from the surroundings by an inner wall 64 of the housing cover 7, the magnetic core 37 and the magnetic base 35 of the magnet housing 26. Via an opening 66 provided in the housing cover 7, the fuel vapor then passes further from the space 62 into a pressure compensation connection 70, which is provided in the basic housing 6 and in the lower housing part 8, for example in the form of a bore, and which opens into the outflow connection 11 downstream of the valve seat 54. The partial flow of the fuel vapor identified by the arrows 58, 59 and 61 in FIG. 1 flows around the valve seat 54. The main stream of the fuel vapor flowing in the direction of arrow 57 from the inflow neck 10 to the outflow neck 11 mixes with the partial stream flowing in the direction of the arrows 58, 59 and 61 downstream of the valve seat 54 and then from the outflow neck 11 to Example to get into the intake pipe 4 via the second hose line 18.
Je nach Hub des Ankers 25 beziehungsweise dessen Abstand seiner Stirnfläche 73 vom Ventilsitz 54 wird dieDepending on the stroke of the armature 25 or its distance from its end face 73 from the valve seat 54, the
Zumeßöffnung 56 von seiner Außenfläche 33 mehr oder weniger freigegeben, so daß der vom Zuströmstutzen 10 in den Abströmstutzen 11 übertretende Brennstoffdampfström entsprechend zugemessen wird. Der Hub des gegen die Ventilfeder 50 arbeitenden Ankers 25 wird dabei durch die Stärke des magnetischen Feldes des Elektromagneten 22 bestimmt. Zur Ansteuerung des Elektromagneten 22 ist ein elektronisches Steuergerät 80 vorgesehen, das über eine elektrische Leitung 81 und über einen am Gehäusedeckel 7 einstückig angeformten Steckeranschluß 82 mit dem Elektromagneten 22 elektrisch verbunden ist.Dosing opening 56 is more or less released from its outer surface 33, so that the fuel vapor flow passing from the inlet nozzle 10 into the outlet nozzle 11 is appropriately metered. The stroke of the armature 25 working against the valve spring 50 is determined by the strength of the magnetic field of the electromagnet 22. To control the electromagnet 22, an electronic control unit 80 is provided which is electrically connected to the electromagnet 22 via an electrical line 81 and via a plug connection 82 integrally molded on the housing cover 7.
Das elektronische Steuergerät 80 übermittelt dem Elektromagneten 22 eine Ansteuerimpulsfolge einer elektrischen Spannung mit einer relativ hohen Frequenz von zum Beispiel 100 Hertz. Die Ansteuerimpulsfolge wird dabei vom elektronischen Steuergerät 80 mit einem vom Steuergerät 80 veränderbaren Tastverhältnis abgegeben. Das Tastverhältnis gibt beispielsweise prozentual den Quotienten der Impulsdauer zum Impulsabstand (Periodendauer) der nacheinander folgenden Impulse an. Eine derartige Ansteuerung ist dem Fachmann als sogenannte Puls-Breiten- Modulation bekannt. Die Erregerspule 23 hat vorzugsweise eine Erregerwicklung, die einen nahezu gleichbleibenden Widerstandswert unabhängig von Temperatureinflüssen desThe electronic control device 80 transmits to the electromagnet 22 a drive pulse sequence of an electrical voltage with a relatively high frequency of, for example, 100 Hertz. The control pulse sequence is emitted by the electronic control unit 80 with a duty cycle that can be changed by the control unit 80. The pulse duty factor indicates, for example, the quotient of the pulse duration to the pulse interval (period duration) of the successive pulses. Such control is known to the person skilled in the art as so-called pulse-width modulation. The excitation coil 23 preferably has an excitation winding which has an almost constant resistance value regardless of the temperature influences of the
Ventils 1 aufweist. Eine derartige, temperaturkompensierte Erregerwicklung kann zum Beispiel aus zwei Wicklungen aufgebaut sein, die aus unterschiedlichem Material bestehen, deren Widerstandswerte so gewählt sind, daß ein Ausgleich der Temperaturabhängigkeit des Widerstandswertes beiderHas valve 1. Such a temperature-compensated excitation winding can be constructed, for example, from two windings which are made of different materials, the resistance values of which are chosen such that the temperature dependence of the resistance value of both is compensated
Wicklungen erfolgt. Hierzu kann beispielsweise eine Wicklung der Erregerspule 23 aus einem Material bestehen, welches einen positiven Temperaturkoeffizienten (PTC-Kaltleiter) aufweist und die andere Wicklung aus einem Material bestehen, welches einen negativen Temperaturkoeffizienten (NTC-Heißleiter) aufweist. Mit der temperaturkompensierten Erregerspule 23 ist es dann möglich, auf eine sogenannte stromgeregelte Endstufe zu verzichten. Anstelle der stromgeregelten Endstufe kann daher eine Endstufe verwendet werden, die dem Elektromagneten 22 eine Spannungsimpulsfolge vorzugsweise mit relativ hoher Frequenz zuführt. Eine derartige Spannungsimpulsfolge läßt sich technisch in besonders einfacher Weise realisieren, beispielsweise in Form einer Transistorschaltung, welche dieWindings. For this purpose, for example, a winding of the excitation coil 23 can consist of a material which has a positive temperature coefficient (PTC thermistor) and the other winding consists of a material that has a negative temperature coefficient (NTC thermistor). With the temperature-compensated excitation coil 23, it is then possible to dispense with a so-called current-controlled output stage. Instead of the current-controlled output stage, an output stage can therefore be used which supplies the electromagnet 22 with a voltage pulse sequence, preferably at a relatively high frequency. Such a voltage pulse sequence can be implemented technically in a particularly simple manner, for example in the form of a transistor circuit which the
Gleichspannungsquelle eines Kraftfahrzeugs, zum Beispiel die einer Starterbatterie, ausnutzt, um zwischen zwei vorgegebenen Werten, beispielsweise 12 Volt und 0 Volt, entsprechend hin und her zu schalten. Eine derartige Spannungsimpulsfolge bewirkt in der Erregerspule 23 einen mittleren Strom, der ein Magnetfeld bestimmter Stärke induziert, um den Anker 25 gegen die Kraft der Ventilfeder 50 vom Ventilsitz 54 wegzubewegen und in eine bestimmte axiale Lage zu bringen. Die axiale Endlage des Ankers 25 hängt dabei von dem angelegten Tastverhältnis der Spannungsimpulsfolge ab. Ist keine Spannung an der Erregerspule 23 angelegt, beziehungsweise fließt kein Strom in der Erregerspule 23, so wird der Anker 25 von derDC voltage source of a motor vehicle, for example that of a starter battery, is used in order to switch back and forth between two predetermined values, for example 12 volts and 0 volts. Such a voltage pulse sequence causes an average current in the excitation coil 23, which induces a magnetic field of a certain strength in order to move the armature 25 away from the valve seat 54 against the force of the valve spring 50 and to bring it into a specific axial position. The axial end position of the armature 25 depends on the applied duty cycle of the voltage pulse train. If no voltage is applied to the excitation coil 23 or no current flows in the excitation coil 23, the armature 25 is removed from the
Ventilfeder 50 gegen den Ventilsitz 54 gedrückt. Dabei liegt der Anker 25 mit seiner Außenfläche 33 an dem Dichtring 53 an und deckt dabei die Zumeßöffnung 56 des Zuströmstutzens 10 ab, so daß eine Strδmungsverbindung vom Zuströmstutzen 10 zum Abströmstutzen 11 unterbrochen wird.Valve spring 50 pressed against the valve seat 54. The armature 25 rests with its outer surface 33 on the sealing ring 53 and covers the metering opening 56 of the inflow connector 10, so that a flow connection from the inflow connector 10 to the outflow connector 11 is interrupted.
Erfindungsgemäß ist die Zumeßöffnung 56 in Form einer Blende ausgebildet, deren Öffnungsquerschnitt so gestaltet ist, daß dem Ventil 1 eine exponentielle Öffnungscharakteristik verliehen wird. Wie in Figur 2, einer Schnittdarstellung entlang einer Linie II-II in Figur 1, eines ersten erfindungsgemäßen Ausführungsbeispiels, dargestellt ist. besitzt die Zumeßöffnung 56 hierzu eine V-Form mit einer Querschnittsfläche, die von zwei kurvenförmig in Richtung zum Ventilsitz 54 hin aufeinanderzulaufenden Querschnittsberandungen 75, 76 und einem kreisförmigen Bogenabschnitt 77 begrenzt wird. Wie ebenfalls in Figur 2 dargestellt ist, kann zwischen den Querschnittsberandungen 75, 76 im Bereich ihres geringsten Abstandes zueinander auch ein kleiner Spalt verbleiben. Durch die trichterförmige Gestaltung der Querschnittsberandungen 75, 76 der Zumeßöffnung 56 ergibt sich, daß mit zunehmendem Kolbenhub H des Ankers 25 eine zunehmend größer werdende, von den Querschnittsberandungen 75, 76 und der Stirnfläche 73 des Ankers 25 begrenzte Querschnittsfläche der Zumeßöffnung 56 freigeben wird, so daß das Volumen des durch die Zumeßöffnung 56 hindurchstrδmenden Brennstoffdampfes entsprechend zunehmen kann.According to the invention, the metering opening 56 is designed in the form of an aperture, the opening cross section of which is designed such that the valve 1 is given an exponential opening characteristic. As shown in Figure 2, a sectional view along a line II-II in Figure 1, a first embodiment of the invention. For this purpose, the metering opening 56 has a V-shape with a cross-sectional area which is delimited by two cross-sectional borders 75, 76 which converge towards one another in the direction of the valve seat 54 and a circular arc section 77. As is also shown in FIG. 2, a small gap can also remain between the cross-sectional borders 75, 76 in the region of their smallest distance from one another. The funnel-shaped design of the cross-sectional borders 75, 76 of the metering opening 56 results in that with increasing piston stroke H of the armature 25 an increasingly larger cross-sectional area of the metering opening 56, limited by the cross-sectional borders 75, 76 and the end face 73 of the anchor 25, is released, so that the volume of the fuel vapor flowing through the metering opening 56 can increase accordingly.
Wie der Verlauf B der Öffnungscharakteristik des erfindungsgemäßen Ventils 1 in Figur 4 zeigt, läßt sich durch die Gestaltung der Querschnittsberandungen 75, 76 ein Ventil 1 erhalten, das mit wachsendem Tastverhältnis T einen zum Beispiel exponentiell ansteigenden Volumenstrom abgibt. Da der Hub H des Ankers 25 von dem Tastverhältnis T der Ansteuerimpulsfolge linear abhängt, ergibt sich, daß zur Verringerung eines relativ hohen Volumenstroms nur relativ wenig Hubweg des Ankers 25 erforderlich ist. Insbesondere ergeben sich damit äußerst kurze Abschaltzeiten von beispielsweise wenigen Millisekunden, um den Volumenstrom des Ventils 1 zum Beispiel auf Null abzusenken. Im Bereich kleiner Tastverhältnisse (zum Beispiel T kleiner 50%) bewirkt eine geringe Änderung des Tastverhältnisses T nur eine kleine Änderung des Volumenstroms, die jedoch erwünscht ist, um gegenüber einem eine lineare Öffnungscharakteristik aufweisenden Ventil (Verlauf A in Figur 4) eine hervorragende Kleinmengendosierbarkeit zu erhalten. ImAs the course B of the opening characteristic of the valve 1 according to the invention in FIG. 4 shows, the design of the cross-sectional borders 75, 76 enables a valve 1 to be obtained which, with an increasing pulse duty factor T, emits an exponentially increasing volume flow. Since the stroke H of the armature 25 is linearly dependent on the pulse duty factor T of the drive pulse sequence, it follows that only a relatively small stroke path of the armature 25 is required to reduce a relatively high volume flow. In particular, this results in extremely short switch-off times of, for example, a few milliseconds in order to reduce the volume flow of valve 1 to zero, for example. In the range of small duty cycles (for example T less than 50%), a small change in the duty cycle T causes only a small change in the volume flow, which is, however, desirable in order to achieve excellent small-quantity metering compared to a valve having a linear opening characteristic (curve A in FIG. 4) receive. in the
Bereich größerer Tastverhältnisse (zum Beispiel T größer 50%) bewirkt eine geringe Änderung des Tastverhältnisses T gegenüber einem eine lineare Öffnungscharakteristik aufweisenden Ventil (Verlauf A) eine relativ große Änderung des Volumenstroms, so daß eine schnelle Regelung hoher Volumenströme möglich ist.Range of larger duty cycles (for example T greater than 50%) causes a slight change in the duty cycle T compared to a valve with a linear opening characteristic (curve A), a relatively large change in the volume flow, so that rapid control of high volume flows is possible.
Wie in Figur 3, einer Schnittdarstellung entlang einer Linie III-III in Figur 1, eines zweiten erfindungsgemäßen Ausführungsbeispiels, dargestellt ist, kann die Zumeßöffnung 56 auch dergestalt sein, daß die Querschnittsberandungen 75, 76 einen Kurvenverlauf aufweisen, welcher, bezogen auf die in Figur 3 eingezeichneten Koordinatenachsen x, y eines kartesischen Koordinatensystems mit einer zur Längsachse 17 parallelen x-Achse, von einer Exponentialfunktion, insbesondere einer natürlichen Exponentialfunktion, beschreibbaren Natur ist. Dabei haben dieAs shown in FIG. 3, a sectional view along a line III-III in FIG. 1, of a second exemplary embodiment according to the invention, the metering opening 56 can also be designed in such a way that the cross-sectional boundaries 75, 76 have a curve which, based on that in FIG 3 drawn in coordinate axes x, y of a Cartesian coordinate system with an x axis parallel to the longitudinal axis 17, of an exponential function, in particular a natural exponential function, can be described. They have
Querschnittsberandungen 75, 76 dem Ventilsitz 54 zugewandt ihren geringsten Abstand beziehungsweise sogar ihren Berührungspunkt, während mit größer werdendem Abstand vom Ventilsitz 54 auch der Abstand der Querschnittsberandungen 75, 76 zueinander zunimmt. Durch den exponentiellen Verlauf der Querschnittsberandungen 75, 76 ist eine weitere Verbesserung der Kleinmengendosierbarkeit des Ventils 1 möglich. Der maximale Hub H des Ankers 25 kann dabei derart eingestellt sein, daß der Anker 25 mit seiner Stirnfläche 73 bei maximalem Hub höchstens Endpunkte 85, 86 derCross-sectional borders 75, 76 facing the valve seat 54 their smallest distance or even their point of contact, while the distance of the cross-sectional borders 75, 76 from one another also increases with increasing distance from the valve seat 54. The exponential course of the cross-sectional boundaries 75, 76 makes it possible to further improve the small-quantity metering of the valve 1. The maximum stroke H of the armature 25 can be set such that the armature 25 with its end face 73 at maximum stroke, at most end points 85, 86 of the
Querschnittsberandungen 75 beziehungsweise 76 erreicht, so daß der Anker 25 nur eine Querschnittsfläche der Zumeßöffnung 56 mit exponentiellen Querschnittsberandungen 75, 76 freigibt.Cross-sectional borders 75 and 76 are reached so that the armature 25 only exposes a cross-sectional area of the metering opening 56 with exponential cross-sectional borders 75, 76.
Die im Ventilgehäuse 6, 7, 8 vorgesehene Druckausgleichsverbindung 70 ermöglicht außerdem, daß im angehobenen Zustand des Ankers 25 der Unterdruck des Ansaugrohres 4 sowohl an der Stirnfläche 73 des Ankers 25 wie auch an der gegenüberliegenden Bodenfläche 48 derThe pressure compensation connection 70 provided in the valve housing 6, 7, 8 also enables the underpressure of the intake pipe 4 in the raised state of the armature 25 both on the end face 73 of the armature 25 and on the opposite bottom surface 48 of the
Ausnehmung 36 am Anker 25 herrscht. Vorzugsweise besitzen die Stirnfläche 73 und die Bodenfläche 48 des Ankers 25 etwa eine gleich große Angriffsfläche, wodurch ein Druckausgleich beziehungsweise Kräfteausgleich am Anker 25 bei unterschiedlichen Ansaugrohrunterdrücken bewirkt wird, so daß die Zumessung des Brennstoffdampfvolumens unabhängig von dem im Ansaugrohr 4 herrschenden Unterdruck ist. Hierzu ist es allerdings erforderlich, die Strömungswege 10, 11, 42, 62, 66, 70 des Brennstoffdampfes im Ventil 1 von der Umgebung, insbesondere gegenüber einem mit Atmosphärendruck beaufschlagten Innenraum 89 des Elektromagneten 22, abzudichten. Wie in Figur 1 dargestellt ist, kann dieRecess 36 on armature 25 prevails. The end face 73 and the bottom face 48 of the armature 25 preferably have approximately an equal area of attack, whereby a pressure equalization or force equalization on the armature 25 is effected at different intake manifold pressures, so that the metering of the fuel vapor volume is independent of the negative pressure prevailing in the intake manifold 4. For this purpose, however, it is necessary to seal the flow paths 10, 11, 42, 62, 66, 70 of the fuel vapor in the valve 1 from the environment, in particular with respect to an interior space 89 of the electromagnet 22 that is subjected to atmospheric pressure. As shown in Figure 1, the
Abdichtung zum Beispiel mittels einer Dichtung 88 erfolgen, die in Form einer Dichtmanschette ausgebildet ist, welche zum Beispiel im unteren Gehäuseteil 8 innen an der Außenfläche 33 des Ankers 25 dicht anliegt und radial außen zwischen dem Grundgehäuse 6 und dem unteren Gehäuseteil 8 eingespannt ist. Sealing is carried out, for example, by means of a seal 88 which is designed in the form of a sealing sleeve which, for example, lies tightly against the inside of the outer surface 33 of the armature 25 in the lower housing part 8 and is clamped radially on the outside between the base housing 6 and the lower housing part 8.

Claims

Patentansprüche claims
1. Ventil zum dosierten Einleiten von aus einem Brennstofftank einer Brennkraftmaschine verflüchtigtem Brennstoffdampf in ein Ansaugrohr der Brennkraftmaschine, mit einem Ventilgehäuse, das einen Zuströmstutzen zum Anschließen an einen Entlüftungsstutzen des Brennstofftanks oder einem diesem nachgeschalteten Adsorptionsfilter für verflüchtigten Brennstoffdampf und einen Abstromstutzen zum Anschließen an das Ansaugrohr hat, mit einem im Inneren des Ventilgehäuses vorgesehenen, von einem Elektromagneten bewegbaren Anker, der im stromlosen Zustand des Elektromagneten von einer Ventilfeder an einen Ventilsitz angedrückt eine Strömungsverbindung vom Zuströmstutzen zum Abstromstutzen schließt und diese im bestromten Zustand des Elektromagneten öffnet, dadurch gekennzeichnet, daß zwischen dem Zustrδmstutzen (10) und dem Ventilsitz (54) eine durch den Anker (25) steuerbare Zumeßöffnung (56) vorgesehen ist.1.Valve for metered introduction of fuel vapor volatilized from a fuel tank of an internal combustion engine into an intake pipe of the internal combustion engine, with a valve housing which has an inflow connection piece for connection to a ventilation connection piece of the fuel tank or an adsorption filter for volatilized fuel vapor connected downstream thereof and an outflow connection piece for connection to the intake pipe has, provided in the interior of the valve housing, movable by an electromagnet armature, which in the de-energized state of the electromagnet is pressed by a valve spring against a valve seat, closes a flow connection from the inflow nozzle to the outflow nozzle and opens it when the electromagnet is energized, characterized in that between the inflow nozzle (10) and the valve seat (54) are provided with a metering opening (56) which can be controlled by the armature (25).
2. Ventil nach Anspruch 1, dadurch gekennzeichnet, daß die Zumeßöffnung (56) eine V-förmige Querschnittsfläche aufweist.2. Valve according to claim 1, characterized in that the metering opening (56) has a V-shaped cross-sectional area.
3. Ventil nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Zumeßöffnung (56) Querschnittsberandungen (75, 76) hat, die dergestalt sind, daß mit wachsendem Abstand des Ankers (25) vom Ventilsitz (54) eine zunehmend größer werdende Querschnittsfläche der Zumeßöffnung (56) vom Anker (25) freigeben wird. 3. Valve according to claim 1 or 2, characterized in that the metering opening (56) has cross-sectional borders (75, 76) which are such that with increasing distance of the armature (25) from the valve seat (54) an increasingly larger cross-sectional area of the The metering opening (56) from the armature (25) is released.
4. Ventil nach Anspruch 3, dadurch gekennzeichnet, daß die Querschnittsberandungen (75, 76) trichterförmig zum Ventilsitz (54) aufeinanderzulaufend ausgebildet sind.4. Valve according to claim 3, characterized in that the cross-sectional borders (75, 76) are funnel-shaped to the valve seat (54) are designed to converge.
5. Ventil nach Anspruch 4, dadurch gekennzeichnet, daß die5. Valve according to claim 4, characterized in that the
Querschnittsberandungen (75, 76) im Bereich des Ventilsitzes (54) einen geringen Abstand voneinander aufweisen.Cross-sectional borders (75, 76) in the region of the valve seat (54) have a small distance from one another.
6. Ventil nach Anspruch 3 oder 4, dadurch gekennzeichnet, daß der Anker (25) einen maximalen Hub (H) aufweist, der derart bemessen ist, daß bei maximalem Hub (H) höchstens Endpunkte (85, 86) der Querschnittsberandungen (75, 76) erreicht werden.6. Valve according to claim 3 or 4, characterized in that the armature (25) has a maximum stroke (H) which is dimensioned such that at maximum stroke (H) at most end points (85, 86) of the cross-sectional boundaries (75, 76) can be achieved.
7. Ventil nach Anspruch 3, dadurch gekennzeichnet, daß die Querschnittsberandungen (75, 76) einen Kurvenverlauf aufweisen, der von einer Exponentialfunktion, insbesondere einer natürlichen Exponentialfunktion, beschreibbaren Natur ist.7. Valve according to claim 3, characterized in that the cross-sectional boundaries (75, 76) have a curve which is of an exponential function, in particular a natural exponential function, can be described.
8. Ventil nach Anspruch 1, dadurch gekennzeichnet, daß der Anker (25) hohlzylindrisch ausgebildet ist.8. Valve according to claim 1, characterized in that the armature (25) is hollow cylindrical.
9. Ventil nach Anspruch 8, dadurch gekennzeichnet, daß das Ventilgehäuse (6, 7, 8) eine Druckausgleichsverbindung (70) aufweist, die einen Teilstrom des Brennstoffdampfes um den Ventilsitz (54) im Ventil (1) herumführt, so daß im abgehobenen Zustand des Ankers (25) an seinen beiden Enden (32, 34) ein im wesentlichen gleich großer Druck wie im Abströmstutzen (11) herrscht.9. Valve according to claim 8, characterized in that the valve housing (6, 7, 8) has a pressure compensation connection (70) which leads a partial flow of the fuel vapor around the valve seat (54) in the valve (1), so that in the raised state of the armature (25) at both ends (32, 34) there is essentially the same pressure as in the outflow connection piece (11).
10. Ventil nach Anspruch 9, dadurch gekennzeichnet, daß Endflächen (48, 73) der Enden (32, 34) des Ankers (25) in etwa die gleiche Größe aufweisen.10. Valve according to claim 9, characterized in that end faces (48, 73) of the ends (32, 34) of the armature (25) have approximately the same size.
11. Ventil nach Anspruch 1, dadurch gekennzeichnet, daß zur Lagerung des Ankers (25) eine Führungshülse (24) im Ventilgehäuse (6) untergebracht ist, deren Außenfläche (39) mit radialem Abstand zu einem Spulenträger (27) einer Erregerspule (23) des Elektromagneten (22) angeordnet ist.11. Valve according to claim 1, characterized in that for mounting the armature (25) a guide sleeve (24) in Valve housing (6) is housed, the outer surface (39) of which is arranged at a radial distance from a coil carrier (27) of an excitation coil (23) of the electromagnet (22).
12. Ventil nach Anspruch 9, dadurch gekennzeichnet, daß am Anker (25) eine Dichtung (88) vorgesehen ist, welche zwei Gehäuseteile (6, 8) des Ventils (1) voneinander abdichtet.12. Valve according to claim 9, characterized in that a seal (88) is provided on the armature (25) which seals two housing parts (6, 8) of the valve (1) from each other.
13. Ventil nach Anspruch 1, dadurch gekennzeichnet, daß der Elektromagnet (22) einen Magnetkern (37) besitzt, der axial verschiebbar ausgebildet ist und der als Anschlag für den Anker (25) dient.13. Valve according to claim 1, characterized in that the electromagnet (22) has a magnetic core (37) which is axially displaceable and which serves as a stop for the armature (25).
14. Ventil nach Anspruch 1, dadurch gekennzeichnet, daß der Elektromagnet (22) eine Erregerspule (23) aufweist, deren14. Valve according to claim 1, characterized in that the electromagnet (22) has an excitation coil (23), the
Widerstandswert nahezu unabhängig von der Temperatur ist. Resistance value is almost independent of the temperature.
EP96918613A 1995-10-27 1996-06-26 Valve for dosed feeding of vaporised fuel from a fuel tank of an internal combustion engine Expired - Lifetime EP0800621B1 (en)

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DE19540021A DE19540021A1 (en) 1995-10-27 1995-10-27 Valve for the metered introduction of fuel vapor volatilized from a fuel tank of an internal combustion engine
DE19540021 1995-10-27
PCT/DE1996/001120 WO1997016640A1 (en) 1995-10-27 1996-06-26 Valve for dosed feeding of vaporised fuel from a fuel tank of an internal combustion engine

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CN1166195A (en) 1997-11-26
KR980700514A (en) 1998-03-30
ES2126404T3 (en) 1999-03-16
DE19540021A1 (en) 1997-04-30
DE59600906D1 (en) 1999-01-14
WO1997016640A1 (en) 1997-05-09
JPH10512346A (en) 1998-11-24
EP0800621B1 (en) 1998-12-02
US5791318A (en) 1998-08-11

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