EP0966655A1 - Level metering device for a fuel tank of a motor vehicle - Google Patents

Level metering device for a fuel tank of a motor vehicle

Info

Publication number
EP0966655A1
EP0966655A1 EP98937410A EP98937410A EP0966655A1 EP 0966655 A1 EP0966655 A1 EP 0966655A1 EP 98937410 A EP98937410 A EP 98937410A EP 98937410 A EP98937410 A EP 98937410A EP 0966655 A1 EP0966655 A1 EP 0966655A1
Authority
EP
European Patent Office
Prior art keywords
fuel tank
fuel
measuring tube
level
delivery unit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98937410A
Other languages
German (de)
French (fr)
Inventor
Hans Braun
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 EP0966655A1 publication Critical patent/EP0966655A1/en
Withdrawn legal-status Critical Current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
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/0047—Layout or arrangement of systems for feeding fuel
    • F02M37/0052—Details on the fuel return circuit; Arrangement of pressure regulators
    • F02M37/0058—Returnless fuel systems, i.e. the fuel return lines are not entering the fuel tank
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K15/00—Arrangement in connection with fuel supply of combustion engines or other fuel consuming energy converters, e.g. fuel cells; Mounting or construction of fuel tanks
    • B60K15/03—Fuel tanks
    • B60K15/06—Fuel tanks characterised by fuel reserve systems
    • B60K15/061—Fuel tanks characterised by fuel reserve systems with level control
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K15/00—Arrangement in connection with fuel supply of combustion engines or other fuel consuming energy converters, e.g. fuel cells; Mounting or construction of fuel tanks
    • B60K15/03—Fuel tanks
    • B60K15/077—Fuel tanks with means modifying or controlling distribution or motion of fuel, e.g. to prevent noise, surge, splash or fuel starvation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/14—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measurement of pressure
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/14—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measurement of pressure
    • G01F23/18—Indicating, recording or alarm devices actuated electrically
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K15/00—Arrangement in connection with fuel supply of combustion engines or other fuel consuming energy converters, e.g. fuel cells; Mounting or construction of fuel tanks
    • B60K15/03—Fuel tanks
    • B60K2015/0321—Fuel tanks characterised by special sensors, the mounting thereof
    • B60K2015/03217—Fuel level sensors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D33/00—Controlling delivery of fuel or combustion-air, not otherwise provided for
    • F02D33/003—Controlling the feeding of liquid fuel from storage containers to carburettors or fuel-injection apparatus ; Failure or leakage prevention; Diagnosis or detection of failure; Arrangement of sensors in the fuel system; Electric wiring; Electrostatic discharge
    • F02D33/006—Controlling the feeding of liquid fuel from storage containers to carburettors or fuel-injection apparatus ; Failure or leakage prevention; Diagnosis or detection of failure; Arrangement of sensors in the fuel system; Electric wiring; Electrostatic discharge depending on engine operating conditions, e.g. start, stop or ambient conditions
    • 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
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/0076—Details of the fuel feeding system related to the fuel tank
    • F02M37/0082—Devices inside the fuel tank other than fuel pumps or filters
    • 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
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/04—Feeding by means of driven pumps
    • F02M37/08—Feeding by means of driven pumps electrically driven
    • F02M37/10—Feeding by means of driven pumps electrically driven submerged in fuel, e.g. in reservoir
    • F02M37/106—Feeding by means of driven pumps electrically driven submerged in fuel, e.g. in reservoir the pump being installed in a sub-tank
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8158—With indicator, register, recorder, alarm or inspection means
    • Y10T137/8326—Fluid pressure responsive indicator, recorder or alarm

Definitions

  • the invention relates to a level measuring device for a fuel tank of a motor vehicle according to the preamble of claim 1.
  • Such a fill level measuring device is known from DE 39 14 637 AI.
  • This fill level measuring device has a measuring tube arranged in the fuel tank, which extends from the bottom of the fuel tank to at least the height of the maximum fill level of the fuel tank and is conveyed into the fuel.
  • the level measuring device also has a differential pressure sensor, which is connected with its one measuring input to the lower end of the measuring tube and with its other measuring input is exposed to the liquid pressure at the bottom of the fuel tank.
  • the measuring tube has an overflow opening which is arranged at least at the level of the maximum fill level of the fuel tank. The measuring tube can be emptied through an opening located near the bottom of the fuel tank or a valve to the level of the current fill level of the fuel tank.
  • the fill level is determined in an evaluation device from the difference between the output signals of the differential pressure sensor with the measuring tube filled up to the overflow opening and with the current fill level of the Fuel tank emptied measuring tube.
  • the delivery of fuel into the measuring tube takes place via a return line through which fuel that is not used by the internal combustion engine of the motor vehicle is returned to the fuel tank. The one through the
  • Return line fuel flowing may be heated so that there is a temperature difference between the fuel in the measuring tube and the fuel in the fuel tank, which in turn results in a difference in the density of the fuel in the measuring tube compared to the density of the fuel in the fuel tank, which leads to Errors in the output signals of the differential pressure sensor.
  • fuel delivery systems are also known in which there is no return flow from the internal combustion engine to
  • Fuel tank is present, so that the known level measuring device can not be used.
  • the fill level measuring device according to the invention for a fuel tank of a motor vehicle has the advantage that the fuel fed into the measuring tube is not heated and that use in fuel delivery systems without return is possible.
  • FIG. 1 shows a fuel tank of a motor vehicle with the level measuring device arranged therein according to a first embodiment with a filled measuring tube
  • FIG. 2 shows the fuel tank with the level measuring device with an empty measuring tube
  • FIG. 3 shows the fuel tank with the level measuring device according to a second embodiment.
  • a fill level measuring device 12 is arranged, which serves to determine the fill level of the fuel tank 10, which is shown in a known manner on a display instrument 34 arranged in the driver's field of vision.
  • the fill level measuring device 12 has a vertically extending measuring tube 14 arranged in the fuel tank 10, the cross section of which is considerably smaller than the cross section of the fuel tank 10.
  • the measuring tube 14 can be made of plastic or metal, for example, and extends from the bottom 16 of the fuel tank 10 to close to the ceiling 18. Near its upper end 20, the measuring tube 14 has an overflow opening 22 which opens into the fuel tank 10.
  • the fill level measuring device 12 also has a differential pressure sensor 24 arranged in the fuel tank 10.
  • the differential pressure sensor 24 has two measurement inputs
  • a measuring input 26 being connected to the lower end 30 of the measuring tube 14 and thus being acted upon by the hydrostatic pressure of the liquid column in the measuring tube 14.
  • the other measuring input 28 of the differential pressure sensor 24 is connected to the bottom 16 of the fuel tank 10 and thus acted upon by the hydrostatic pressure of the liquid column in the fuel tank 10.
  • the signal output of the differential pressure sensor 24 is connected to an evaluation device 32, which in turn controls the display instrument 34.
  • a micro-mechanical pressure sensor which is particularly inexpensive, is preferably used as the differential pressure sensor 24.
  • a delivery unit 40 is arranged in the fuel tank 10, through which fuel is delivered from the fuel tank 10 to the injection system 44 of an internal combustion engine 46 of the motor vehicle.
  • the conveyor unit 40 has a pump part 41 and a drive part 42, which is preferably designed as an electric motor.
  • the delivery unit 40 is held in a manner not shown in the fuel tank 10, wherein a pot 48 can be provided in the fuel tank 10, from which the delivery unit 40 sucks fuel.
  • the pot ensures that the delivery unit 40 can deliver sufficient fuel even when the fuel tank 10 is low.
  • Fuel can be conveyed from the fuel tank 10 into the pot 48 by a jet pump or another pump.
  • Operation of the internal combustion engine 46 is not continuously operated with the same delivery rate, but rather the operation of the delivery unit 40 is controlled or regulated in such a way that the amount of fuel consumed in the current operating state of the internal combustion engine 46 is conveyed through this.
  • the electrical power supplied to the drive part 42 of the conveyor unit 40 or the electrical voltage applied to it can be varied. Due to this demand-controlled operation of the conveyor unit 40, there is no return for the Internal combustion engine 46 requires unused fuel in the fuel tank 10.
  • a pressure regulator 45 is arranged in the fuel tank 10 which has an inlet which is connected to the pressure side of the delivery unit 40 and which has an outlet which is connected to the injection system 44 Internal combustion engine 46 is connected, and which has a return 47 which opens into the fuel tank 10.
  • the pressure regulator 45 adjusts an at least approximately constant fuel pressure in the injection system 44. In this embodiment, too, no return line from the internal combustion engine 46 to the fuel tank 10 is required.
  • the pressure regulator 45 can, for example, together with the delivery unit 40
  • Fuel tank 10 may be held or, as shown in FIG. 1, on a cover 38 closing an opening 36 of the fuel tank 10.
  • Fuel line 50 for connection to the injection system 44 From the fuel line 50 or directly from the pressure side of the delivery unit 40, for example from a connection piece 52 of the delivery unit 40, a further fuel line 54 branches off into the measuring tube 14
  • Level measuring device 12 opens near its lower end 30.
  • the fuel line 54 opening into the measuring tube 14 has a substantially smaller cross-section than the fuel line 50 leading to the injection system 44.
  • the fuel line 54 opening into the measuring tube 14 is thus throttled relative to the fuel line 50 leading to the injection system 44, so that one of the delivery unit 40 much larger amount of fuel is delivered to the injection system 44 than in the measuring tube 14. If the delivery unit 40 is operated, it delivers fuel to the injection system 44 via the fuel line 50 and delivers fuel into the measuring tube 14 via the fuel line 54.
  • the measuring tube 14 is filled with fuel until it lo in height
  • Overflow opening 22 is, as shown in Figure 1. With further fuel delivery into the measuring tube 14, the fuel flows back into the fuel tank 10 via the overflow opening 22. When the delivery unit 40 is operating, a fuel column with the defined height lo is thus set in the measuring tube 14, which has a defined hydrostatic pressure at the first measuring input 26 Differential pressure sensor 24 causes. The second measurement input 28 of the differential pressure sensor 24 is the one through the fuel column with the height h of the fuel in
  • Fuel tank 10 exposed to hydrostatic pressure.
  • the current height h of the fuel column in the fuel tank 10 is the fill level of the fuel tank 10.
  • the output signal u (t) of the differential pressure sensor 24 is therefore proportional to the
  • the output signal u (t) of the differential pressure sensor 24 is fed to the evaluation device 32, which determines the output signal h (t) from it according to the following equation:
  • g is the acceleration due to gravity
  • t> the density of the fuel
  • k the transmission factor (sensitivity) of the differential pressure sensor 24.
  • uo is the output signal of the differential pressure sensor 24 for the condition that the height of the liquid column in the measuring tube 14 is equal to the height h of the fuel in the fuel tank 10 is. This state occurs when the conveyor unit 40 is not operating becomes. In this case, the measuring tube 14 runs empty from the level of the fuel to the overflow opening 22 at the height lo up to the current height h of the fuel in the fuel tank, as shown in FIG. 2.
  • FIGS. 1 and 2 show the fill level measuring device 12 according to a first embodiment, in which, when the delivery unit 40 is switched off, fuel can flow out of the measuring tube 14 through the fuel line 54 and the delivery unit 40 into the fuel tank 10.
  • the measuring tube 14 near its lower end 30 or the fuel line 54 has a small opening 56 through which fuel can flow out of the measuring tube 14 into the fuel tank 10.
  • the opening 56 is dimensioned in such a way that less fuel can flow through it in a certain time unit than fuel is conveyed into the measuring tube 14 by the delivery unit 40 during its operation in this time unit.
  • the output signal uo of the differential pressure sensor present in this state 24 represents its offset. This offset is subject to a certain drift during the life of the differential pressure sensor 24, which would impair the accuracy of the level measurement. This offset is taken into account in the evaluation device 32 in accordance with the equation given above, so that it does not lead to errors in the determination of the fill level.
  • the output signal uo of the differential pressure sensor 24 can in each case be determined after the delivery unit 40 has been switched off and stored in the evaluation device 32. After each shutdown of the conveyor unit 40, the for Output signal uo stored value can be updated.
  • the fill level signal h (t) determined by the evaluation device 32 is continuously displayed on the display device, not shown.
  • FIG. 3 shows the fill level measuring device 12 according to a second exemplary embodiment, the basic structure being the same as in the first exemplary embodiment.
  • a valve 60 is arranged in the fuel line 54 between the delivery unit 40 and the measuring tube 14.
  • the valve 60 is between a first position shown in solid lines in FIG. 3, in which it connects the measuring tube 14 to the delivery unit 40 via the fuel line 54, and a second position, shown in FIG. 3 with dashed lines, in which the fuel line 54 opens and connects the measuring tube 14 to the fuel tank 10, switchable.
  • the valve 60 can be designed as a solenoid valve that is electrically switchable. The switchover of the valve 60 between its two positions can be controlled by the evaluation device 32. Normally, the valve 60 is in the operation of the delivery unit 40 in the position in which the measuring tube 14 is connected to the delivery unit 40 and thus is filled with fuel up to the level lo, so that by the
  • the current fill level h of the fuel tank 10 can be determined.
  • the valve 60 is switched to its other position in order to connect the measuring tube 14 to the fuel tank 10 and to determine the output signal uo of the differential pressure sensor 24 and thus to compensate for the zero point drift. This switchover of the valve 60 can not only take place when the internal combustion engine 46 is switched off Conveyor unit 40 take place, but also during the operation of the conveyor unit 40th
  • valve 60 can also be designed in such a way that the one in this position
  • Fuel line 54 is released and the fuel line 54 is blocked in its other position.
  • an opening 14 is provided in the fuel line 54 between the valve 60 and the measuring tube 14 or in the region of the lower end 30 of the measuring tube 14 in order to enable the measuring tube 14 to be emptied.

Abstract

The invention relates to a level metering device (2) comprising a metering tube (14) placed in a fuel tank (10). Said metering tube (14) is filled with a part of the fuel flow which is fed to the injection system (44) of the motor vehicle combustion engine (46) by a feed unit (40) placed in the fuel tank (10). A differential pressure sensor (24) is subjected to a hydrostatic pressure applied to the lower end (30) of the metering tube (14) at one metering input (26), and to a hydrostatic pressure applied to the bottom (16) of the fuel tank (10), at its other metering input (28). During operation of the feed unit (40), a fuel column of a known height (lo) is defined in the metering tube (14) so that the output signal (u) of the differential pressure sensor (24) enables determination of the actual level (h(t)) of the fuel tank (10). The metering tube (14) has an opening (56) for lowering the level in the metering tube (14), adjacent to its lower end (30), when the feed unit (40) is stopped, until same level is defined in the metering tube and in the fuel tank (10) and until the offset of the differential pressure sensor (24) can be determined.

Description

Füllstandsmeßvorrichtung für einen Kraftstoffbehälter eines KraftfahrzeugsLevel measuring device for a fuel tank of a motor vehicle
Stand der TechnikState of the art
Die Erfindung geht aus von einer Füllstandsmeßvorrichtung für einen Kraftstoffbehälter eines Kraf fahrzeugs nach der Gattung des Anspruchs 1.The invention relates to a level measuring device for a fuel tank of a motor vehicle according to the preamble of claim 1.
Eine solche Füllstandsmeßvorrichtung ist durch die DE 39 14 637 AI bekannt. Diese Füllstandsmeßvorrichtung weist ein im Kraftstoffbehälter angeordnetes Meßrohr auf, das sich ausgehend vom Boden des Kraftstoffbehälters bis wenigstens zur Höhe des maximalen Füllstands des Kraftstoffbehälters erstreckt und in das Kraftstoff gefördert wird. Die Füllstandsmeßvorrichtung weist außerdem einen Differenzdrucksensor auf, der mit seinem einen Meßeingang mit dem unteren Ende des Meßrohrs verbunden ist und der mit seinem anderen Meßeingang dem Flussigkeitsdruck am Boden des Kraftstoffbehälters ausgesetzt ist. Das Meßrohr weist eine Überlauföffnung auf, die wenigstens in Höhe des maximalen Füllstands des Kraftstoffbehälters angeordnet ist. Das Meßrohr ist durch eine nahe dem Boden des Kraf stoffbehälters angeordnete Öffnung oder ein Ventil auf die Höhe des aktuellen Füllstands des Kraftstoffbehälters entleerbar. Die Füllstandsbestimmung erfolgt in einer Auswerteeinrichtung aus der Differenz der Ausgangssignale des Differenzdrucksensors bei bis zur Überlauföffnung gefülltem Meßrohr und bei bis zum aktuellen Füllstand des Kraftstoffbehälters entleertem Meßrohr erfolgt. Die Förderung von Kraftstoff in das Meßrohr erfolgt über eine Rücklaufleitung, durch die von der Brennkraftmaschine des Kraftfahrzeugs nicht verbrauchter Kraftstoff in den Kraftstoffbehälter zurückgeführt wird. Der durch dieSuch a fill level measuring device is known from DE 39 14 637 AI. This fill level measuring device has a measuring tube arranged in the fuel tank, which extends from the bottom of the fuel tank to at least the height of the maximum fill level of the fuel tank and is conveyed into the fuel. The level measuring device also has a differential pressure sensor, which is connected with its one measuring input to the lower end of the measuring tube and with its other measuring input is exposed to the liquid pressure at the bottom of the fuel tank. The measuring tube has an overflow opening which is arranged at least at the level of the maximum fill level of the fuel tank. The measuring tube can be emptied through an opening located near the bottom of the fuel tank or a valve to the level of the current fill level of the fuel tank. The fill level is determined in an evaluation device from the difference between the output signals of the differential pressure sensor with the measuring tube filled up to the overflow opening and with the current fill level of the Fuel tank emptied measuring tube. The delivery of fuel into the measuring tube takes place via a return line through which fuel that is not used by the internal combustion engine of the motor vehicle is returned to the fuel tank. The one through the
Rücklaufleitung strömende Kraftstoff ist unter Umständen erhitzt, so daß eine Temperaturdifferenz zwischen dem im Meßrohr befindlichen Kraftstoff und dem im Kraftstoffbehälter befindlichen Kraftstoff vorhanden ist, die wiederum eine Differenz der Dichte des Kraftstoffs im Meßrohr gegenüber der Dichte des Kraftstoffs im Kraftstoffbehälter zur Folge hat, was zu Fehlern in den AusgangsSignalen des Differnezdrucksensors führt. Darüberhinaus sind auch Kraftstoffördersysteme bekannt, bei denen kein Rücklauf von der Brennkraftmaschine zumReturn line fuel flowing may be heated so that there is a temperature difference between the fuel in the measuring tube and the fuel in the fuel tank, which in turn results in a difference in the density of the fuel in the measuring tube compared to the density of the fuel in the fuel tank, which leads to Errors in the output signals of the differential pressure sensor. In addition, fuel delivery systems are also known in which there is no return flow from the internal combustion engine to
Kraftstoffbehälter vorhanden ist, so daß die bekannte Füllstandsmeßvorrichtung nicht verwendbar ist.Fuel tank is present, so that the known level measuring device can not be used.
Vorteile der ErfindungAdvantages of the invention
Die erfindungsgemäße Füllstandsmeßvorrichtung für einen Kraftstoffbehälter eines Kraftfahrzeugs hat demgegenüber den Vorteil, daß der in das Meßrohr geförderte Kraftstoff nicht erwärmt ist und daß eine Verwendung bei Kraftstoffördersystemen ohne Rücklauf möglich ist.The fill level measuring device according to the invention for a fuel tank of a motor vehicle has the advantage that the fuel fed into the measuring tube is not heated and that use in fuel delivery systems without return is possible.
In den abhängigen Ansprüchen sind vorteilhafte Ausgestaltungen und Weiterbildungen der erfindungsgemäßen Füllstandsmeßvorrichtung angegeben .Advantageous refinements and developments of the fill level measuring device according to the invention are specified in the dependent claims.
Zeichnungdrawing
Zwei Ausführungsbeispiele der erfindungsgemäßen Füllstandsmeßvorrichtung sind in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 einen Kraftstoffbehälter eines Kraftfahrzeugs mit darin angeordneter Füllstandsmeßvorrichtung gemäß einem ersten Ausführungsbeispiel mit gefülltem Meßrohr, Figur 2 den Kraftstoffbehälter mit der Füllstandsmeßvorrichtung mit entleertem Meßrohr und Figur 3 den Kraftstoffbehälter mit der Füllstandsmeßvorrichtung gemäß einem zweiten Ausführungsbeispiel .Two embodiments of the level measuring device according to the invention are shown in the drawing and explained in more detail in the following description. It 1 shows a fuel tank of a motor vehicle with the level measuring device arranged therein according to a first embodiment with a filled measuring tube, FIG. 2 shows the fuel tank with the level measuring device with an empty measuring tube and FIG. 3 shows the fuel tank with the level measuring device according to a second embodiment.
Beschreibung der AusführungsbeispieleDescription of the embodiments
In den Figuren 1 bis 3 ist jeweils ein Kraftstoffbehälter 10 eines Kraftfahrzeugs dargestellt, der aus Metall oder Kunststoff bestehen kann. Im Kraftstoffbehälter 10 ist eine Füllstandsmeßvorrichtung 12 angeordnet, die dazu dient, den Füllstand des Kraftstoffbehälters 10 zu ermitteln, der in bekannter Weise auf einem im Sichtbereich des Fahrzeuglenkers angeordneten Anzeigeinstrument 34 dargestellt wird. Die Füllstandsmeßvorrichtung 12 weist ein im Kraftstoffbehälter 10 angeordnetes, vertikal verlaufendes Meßrohr 14, dessen Querschnitt gegenüber dem Querschnitt des Kraftstoffbehälters 10 wesentlich kleiner ist. Das Meßrohr 14 kann beispielsweise aus Kunststoff oder Metall bestehen und erstreckt ausgehend vom Boden 16 des Kraftstoffbehälters 10 bis nahe an dessen Decke 18. Nahe seinem oberen Ende 20 weist das Meßrohr 14 eine Überströmöffnung 22 auf, die in den Kraftstoffbehälter 10 mündet.1 to 3 each show a fuel tank 10 of a motor vehicle, which can be made of metal or plastic. In the fuel tank 10, a fill level measuring device 12 is arranged, which serves to determine the fill level of the fuel tank 10, which is shown in a known manner on a display instrument 34 arranged in the driver's field of vision. The fill level measuring device 12 has a vertically extending measuring tube 14 arranged in the fuel tank 10, the cross section of which is considerably smaller than the cross section of the fuel tank 10. The measuring tube 14 can be made of plastic or metal, for example, and extends from the bottom 16 of the fuel tank 10 to close to the ceiling 18. Near its upper end 20, the measuring tube 14 has an overflow opening 22 which opens into the fuel tank 10.
Die Füllstandsmeßvorrichtung 12 weist außerdem einen im Kraftstoffbehälter 10 angeordneten Differenzdrucksensor 24 auf. Der Differenzdrucksensor 24 weist zwei MeßeingängeThe fill level measuring device 12 also has a differential pressure sensor 24 arranged in the fuel tank 10. The differential pressure sensor 24 has two measurement inputs
26,28 auf, wobei ein Meßeingang 26 mit dem unteren Ende 30 des Meßrohrs 14 verbunden ist und somit vom hydrostatischen Druck der Flüssigkeitssäule im Meßrohr 14 beaufschlagt ist. Der andere Meßeingang 28 des Differenzdrucksensors 24 ist mit dem Boden 16 des Kraftstoffbehälters 10 verbunden und somit vom hydrostatischen Druck der Flüssigkeitssäule im Kraftstoffbehälter 10 beaufschlagt. Der Signalausgang des Differenzdrucksensors 24 ist mit einer Auswerteeinrichtung 32 verbunden, durch die wiederum das Anzeigeinstrument 34 angesteuert wird. Als Differenzdrucksensor 24 wird vorzugsweise ein mikromeachnischer Drucksensor verwendet, der besonders kostengünstig ist.26, 28, a measuring input 26 being connected to the lower end 30 of the measuring tube 14 and thus being acted upon by the hydrostatic pressure of the liquid column in the measuring tube 14. The other measuring input 28 of the differential pressure sensor 24 is connected to the bottom 16 of the fuel tank 10 and thus acted upon by the hydrostatic pressure of the liquid column in the fuel tank 10. The signal output of the differential pressure sensor 24 is connected to an evaluation device 32, which in turn controls the display instrument 34. A micro-mechanical pressure sensor, which is particularly inexpensive, is preferably used as the differential pressure sensor 24.
Im Kraftstoffbehälter 10 ist ein Förderaggregat 40 angeordnet, durch das Kraftstoff aus dem Kraftstoffbehälter 10 zur Einspritzanlage 44 einer Brennkraftmaschine 46 des Kraftfahrzeugs gefördert wird. Das Förderaggregat 40 weist einen Pumpenteil 41 und einen Antriebsteil 42 auf, der vorzugsweise als Elektromotor ausgebildet ist. Das Förderaggregat 40 ist in nicht näher dargestellter Weise im Kraftstoffbehälter 10 gehalten, wobei im Kraftstoffbehälter 10 ein Topf 48 vorgesehen sein kann, aus dem das Förderaggregat 40 Kraftstoff ansaugt. Durch den Topf wird sichergestellt, daß das Förderaggregat 40 auch bei geringem Füllstand des Kraftstoffbehälters 10 ausreichend Kraftstoff fördern kann. In den Topf 48 kann durch eine Strahlpumpe oder eine andere Pumpe Kraftstoff aus dem Kraftstoffbehälter 10 gefördert werden.A delivery unit 40 is arranged in the fuel tank 10, through which fuel is delivered from the fuel tank 10 to the injection system 44 of an internal combustion engine 46 of the motor vehicle. The conveyor unit 40 has a pump part 41 and a drive part 42, which is preferably designed as an electric motor. The delivery unit 40 is held in a manner not shown in the fuel tank 10, wherein a pot 48 can be provided in the fuel tank 10, from which the delivery unit 40 sucks fuel. The pot ensures that the delivery unit 40 can deliver sufficient fuel even when the fuel tank 10 is low. Fuel can be conveyed from the fuel tank 10 into the pot 48 by a jet pump or another pump.
Es kann vorgesehen sein, daß das Förderaggregat 40 beimIt can be provided that the conveyor unit 40 at
Betrieb der Brennkraftmaschine 46 nicht ständig mit gleicher Förderleistung betrieben wird, sondern der Betrieb des Förderaggregats 40 derart gesteuert oder geregelt wird, daß durch dieses die im aktuellen Betriebszustand von der Brennkraf maschine 46 verbrauchte Kraf stoffmenge gefördert wird. Hierzu kann die dem Antriebsteil 42 des Förderaggregats 40 zugeführte elektrische Leistung bzw. die an diesen angelegte elektrische Spannung variiert werden. Durch diesen bedarfsabhängig gesteuerten Betrieb des Förderaggregats 40 ist kein Rücklauf für von der Brennkraftmaschine 46 nicht verbrauchten Kraftstoff in den Kraftstoffbehälter 10 erforderlich. Alternativ zu diesem bedarfsabhängig gesteuerten Betrieb des Förderaggregats 40 kann auch vorgesehen sein, daß im Kraftstoffbehälter 10 ein Druckregler 45 angeordnet ist, der einen Einlaß aufweist, welcher mit der Druckseite des Förderaggregats 40 verbunden ist, der einen Auslaß aufweist, welcher mit der Einspritzanlage 44 der Brennkraftmaschine 46 verbunden ist, und der einen Rücklauf 47 aufweist, welcher in den Kraftstoffbehälter 10 mündet. Durch den Druckregler 45 wird ein zumindest annähernd konstanter Kraftstoffdruck in der Einspritzanlage 44 eingestellt. Auch bei dieser Ausführung ist keine Rücklaufleitung von der Brennkraftmaschine 46 zum Kraftstoffbehälter 10 erforderlich. Der Druckregler 45 kann beispielsweise zusammen mit dem Förderaggregat 40 imOperation of the internal combustion engine 46 is not continuously operated with the same delivery rate, but rather the operation of the delivery unit 40 is controlled or regulated in such a way that the amount of fuel consumed in the current operating state of the internal combustion engine 46 is conveyed through this. For this purpose, the electrical power supplied to the drive part 42 of the conveyor unit 40 or the electrical voltage applied to it can be varied. Due to this demand-controlled operation of the conveyor unit 40, there is no return for the Internal combustion engine 46 requires unused fuel in the fuel tank 10. As an alternative to this demand-controlled operation of the delivery unit 40, it can also be provided that a pressure regulator 45 is arranged in the fuel tank 10 which has an inlet which is connected to the pressure side of the delivery unit 40 and which has an outlet which is connected to the injection system 44 Internal combustion engine 46 is connected, and which has a return 47 which opens into the fuel tank 10. The pressure regulator 45 adjusts an at least approximately constant fuel pressure in the injection system 44. In this embodiment, too, no return line from the internal combustion engine 46 to the fuel tank 10 is required. The pressure regulator 45 can, for example, together with the delivery unit 40
Kraftstoffbehälter 10 gehalten sein oder wie in Figur 1 dargestellt an einem eine Öffnung 36 des Kraftstoffbehälters 10 verschließenden Deckel 38.Fuel tank 10 may be held or, as shown in FIG. 1, on a cover 38 closing an opening 36 of the fuel tank 10.
Von der Druckseite des Förderaggregats 40 führt eineOne leads from the pressure side of the conveyor assembly 40
Kraftstoffleitung 50 zur Verbindung mit der Einspritzanlage 44 ab. Von der Kraftstoffleitung 50 oder direkt von der Druckseite des Förderaggregats 40, beispielsweise von einem Stutzen 52 des Förderaggregats 40, zweigt eine weitere Kraf stoffleitung 54 ab, die in das Meßrohr 14 derFuel line 50 for connection to the injection system 44. From the fuel line 50 or directly from the pressure side of the delivery unit 40, for example from a connection piece 52 of the delivery unit 40, a further fuel line 54 branches off into the measuring tube 14
Füllstandsmeßvorrichtung 12 nahe dessen unterem Ende 30 mündet. Die in das Meßrohr 14 mündende Kraftstoffleitung 54 weist einen wesentlich geringeren Querschnitt auf als die zur Einspritzanlage 44 führende Kraf stoffleitung 50. Die in das Meßrohr 14 mündende Kraftstoffleitung 54 ist somit gegenüber der zur Einspritzanlage 44 führenden Kraftstoffleitung 50 gedrosselt, so daß vom Förderaggregat 40 eine wesentlich größere Kraftstoffmenge zur Einspritzanlage 44 gefördert wird als in das Meßrohr 14. Wird das Förderaggregat 40 betrieben, so wird durch dieses über die Kraftstoffleitung 50 Kraftstoff zur Einspritzanlage 44 gefördert und über die Kraftstoffleitung 54 Kraftstoff in das Meßrohr 14 gefördert. Das Meßrohr 14 wird dabei mit Kraftstoff gefüllt, bis dieser bis in der Höhe lo derLevel measuring device 12 opens near its lower end 30. The fuel line 54 opening into the measuring tube 14 has a substantially smaller cross-section than the fuel line 50 leading to the injection system 44. The fuel line 54 opening into the measuring tube 14 is thus throttled relative to the fuel line 50 leading to the injection system 44, so that one of the delivery unit 40 much larger amount of fuel is delivered to the injection system 44 than in the measuring tube 14. If the delivery unit 40 is operated, it delivers fuel to the injection system 44 via the fuel line 50 and delivers fuel into the measuring tube 14 via the fuel line 54. The measuring tube 14 is filled with fuel until it lo in height
Überströmöffnung 22 steht, wie dies in Figur 1 dargestellt ist. Bei weiterer Kraftstofförderung in das Meßrohr 14 strömt der Kraftstoff über die Überströmöffnung 22 wieder in den Kraftstoffbehälter 10. Beim Betrieb des Förderaggregats 40 stellt sich somit im Meßrohr 14 eine Kraftstoffsäule mit der definierten Höhe lo ein, die einen definierten hydrostatischen Druck am ersten Meßeingang 26 des Differenzdrucksensors 24 verursacht. Der zweite Meßeingang 28 des Differenzdrucksensors 24 ist dem durch die Kraftstoffsäule mit der Höhe h des Kraftstoffs imOverflow opening 22 is, as shown in Figure 1. With further fuel delivery into the measuring tube 14, the fuel flows back into the fuel tank 10 via the overflow opening 22. When the delivery unit 40 is operating, a fuel column with the defined height lo is thus set in the measuring tube 14, which has a defined hydrostatic pressure at the first measuring input 26 Differential pressure sensor 24 causes. The second measurement input 28 of the differential pressure sensor 24 is the one through the fuel column with the height h of the fuel in
Kraftstoffbehälter 10 verursachten hydrostatischen Druck ausgesetzt. Die aktuelle Höhe h der Kraf stoffsäule im Kraftstoffbehälter 10 ist der Füllstand des Kraftstoffbehälters 10. Das Ausgangssignal u(t) des Differenzdrucksensors 24 ist damit proportional derFuel tank 10 exposed to hydrostatic pressure. The current height h of the fuel column in the fuel tank 10 is the fill level of the fuel tank 10. The output signal u (t) of the differential pressure sensor 24 is therefore proportional to the
Differenz des hydrostatischen Drucks im Meßrohr 14 und des hydrostatischen Drucks im Kraftstoffbehälter 10. Das Ausgangssignal u(t) des Differenzdrucksensors 24 wird der Auswerteeinrichtung 32 zugeführt, die daraus das Ausgangssignal h(t) gemäß folgender Gleichung ermittelt:Difference of the hydrostatic pressure in the measuring tube 14 and the hydrostatic pressure in the fuel tank 10. The output signal u (t) of the differential pressure sensor 24 is fed to the evaluation device 32, which determines the output signal h (t) from it according to the following equation:
h(t) = lo - Λ -(u(t) - uo) -3- 5h (t) = lo - Λ - (u (t) - uo) - 3 - 5
Hierbei ist g die Fallbeschleunigung, t> die Dichte des Kraftstoffs und k der Übertragungsfaktor (Empfindlichkeit) des Differenzdrucksensors 24. uo ist das Ausgangssignal des Differenzdrucksensors 24 für den Zustand, daß die Höhe der Flüssigkeitssäule im Meßrohr 14 gleich der Höhe h des Kraftstoffs im Kraftstoffbehälter 10 ist. Dieser Zustand stellt sich ein, wenn das Förderaggregat 40 nicht betrieben wird. In diesem Fall läuft das Meßrohr 14 ausgehend vom Stand des Krafstoffs bis zur Überströmöffnung 22 in der Höhe lo leer bis zur aktuellen Höhe h des Kraftstoffs im Kraftstoffbehälter, wie dies in Figur 2 dargestellt ist.Here g is the acceleration due to gravity, t> the density of the fuel and k the transmission factor (sensitivity) of the differential pressure sensor 24. uo is the output signal of the differential pressure sensor 24 for the condition that the height of the liquid column in the measuring tube 14 is equal to the height h of the fuel in the fuel tank 10 is. This state occurs when the conveyor unit 40 is not operating becomes. In this case, the measuring tube 14 runs empty from the level of the fuel to the overflow opening 22 at the height lo up to the current height h of the fuel in the fuel tank, as shown in FIG. 2.
In den Figuren 1 und 2 ist die Füllstandsmeßvorrichtung 12 gemäß einem ersten Ausführungsbeispiel dargestellt, bei dem bei abgeschaltetem Förderaggregat 40 Kraftstoff aus dem Meßrohr 14 durch die Kraftstoffleitung 54 und das Förderaggregat 40 in den Kraftstoffbehälter 10 abfließen kann. Alternativ kann auch vorgesehen sein, daß das Meßrohr 14 nahe seinem unteren Ende 30 oder die Kraftstoffleitung 54 eine kleine Öffnung 56 aufweist, durch die Kraftstoff aus dem Meßrohr 14 in den Kraftstoffbehälter 10 abfließen kann. Die Öffnung 56 ist dabei derart bemessen, daß durch diese in einer bestimmten Zeiteinheit weniger Kraftstoff abfließen kann als durch das Förderaggregat 40 bei dessen Betrieb in dieser Zeiteinheit Kraftstoff in das Meßrohr 14 gefördert wird. Durch die Verbindung des Meßrohrs 14 über die Öffnung 56 oder das Förderaggregat 40 mit dem Kraftstoffbehälter 10 stellt sich im Meßrohr 14 nach dem Prinzip der kommunizierenden Röhren der Kraftstoff mit derselben Höhe h ein wie im Kraftstoffbehälter 10. Das in diesem Zustand vorliegende Ausgangssignal uo des Differenzdrucksensors 24 stellt dessen Offset dar. Dieser Offset unterliegt während der Lebensdauer des Differenzdrucksensors 24 einer gewissen Drift, die die Genauigkeit der Füllstandsmeßung beeinträchtigen würde. Dieser Offset wird in der Auswerteeinrichtung 32 gemäß der vorstehend angegebenen Gleichung berücksichtigt, so daß dieser nicht zu Fehlern in der Ermittlung des Füllstands führt. Das Ausgangssignal uo des Differenzdrucksensors 24 kann jeweils nach dem Abstellen des Förderaggregats 40 ermittelt und in der Auswerteeinrichtung 32 abgespeichert werden. Nach jedem Abstellen des Förderaggregats 40 kann somit der für das Ausgangssignal uo abgespeicherte Wert aktualisiert werden. Das von der Auswerteeinrichtung 32 ermittelte Füllstandssignal h(t) wird kontinuierlich auf der nicht dargestellten Anzeigeeinrichtung angezeigt.FIGS. 1 and 2 show the fill level measuring device 12 according to a first embodiment, in which, when the delivery unit 40 is switched off, fuel can flow out of the measuring tube 14 through the fuel line 54 and the delivery unit 40 into the fuel tank 10. Alternatively, it can also be provided that the measuring tube 14 near its lower end 30 or the fuel line 54 has a small opening 56 through which fuel can flow out of the measuring tube 14 into the fuel tank 10. The opening 56 is dimensioned in such a way that less fuel can flow through it in a certain time unit than fuel is conveyed into the measuring tube 14 by the delivery unit 40 during its operation in this time unit. By connecting the measuring tube 14 via the opening 56 or the delivery unit 40 to the fuel tank 10, the fuel is set in the measuring tube 14 according to the principle of the communicating tubes with the same height h as in the fuel tank 10. The output signal uo of the differential pressure sensor present in this state 24 represents its offset. This offset is subject to a certain drift during the life of the differential pressure sensor 24, which would impair the accuracy of the level measurement. This offset is taken into account in the evaluation device 32 in accordance with the equation given above, so that it does not lead to errors in the determination of the fill level. The output signal uo of the differential pressure sensor 24 can in each case be determined after the delivery unit 40 has been switched off and stored in the evaluation device 32. After each shutdown of the conveyor unit 40, the for Output signal uo stored value can be updated. The fill level signal h (t) determined by the evaluation device 32 is continuously displayed on the display device, not shown.
In Figur 3 ist die Füllstandsmeßvorrichtung 12 gemäß einem zweiten Ausführungsbeispiel dargestellt, wobei der grundsätzliche Aufbau gleich ist wie beim ersten Ausführungsbeispie1. Abweichend zum ersten Ausführungsbeispiel ist in der Kraf stoffleitung 54 zwischen dem Förderaggregat 40 und dem Meßrohr 14 ein Ventil 60 angeordnet. Das Ventil 60 ist zwischen einer in Figur 3 mit durchgezogenen Linien dargestellten ersten Stellung, in der dieses das Meßrohr 14 über die Kraftstoffleitung 54 mit dem Förderaggregat 40 verbindet, und einer in Figur 3 mit gestrichelten Linien dargestellten zweiten Stellung, in der dieses die Kraftstoffleitung 54 öffnet und das Meßrohr 14 mit dem Kraftstoffbehälter 10 verbindet, umschaltbar. Das Ventil 60 kann als Magnetventil ausgebildet sein, das elektrisch schaltbar ist. Die Umschaltung des Ventils 60 zwischen seinen beiden Stellungen kann durch die Auswerteeinrichtung 32 gesteuert werden. Normalerweise befindet sich das Ventil 60 beim Betrieb des Förderaggregats 40 in der Stellung, in der das Meßrohr 14 mit dem Förderaggregat 40 verbunden ist und somit mit Kraftstoff bis zur Höhe lo gefüllt wird, so daß durch denFIG. 3 shows the fill level measuring device 12 according to a second exemplary embodiment, the basic structure being the same as in the first exemplary embodiment. In a departure from the first exemplary embodiment, a valve 60 is arranged in the fuel line 54 between the delivery unit 40 and the measuring tube 14. The valve 60 is between a first position shown in solid lines in FIG. 3, in which it connects the measuring tube 14 to the delivery unit 40 via the fuel line 54, and a second position, shown in FIG. 3 with dashed lines, in which the fuel line 54 opens and connects the measuring tube 14 to the fuel tank 10, switchable. The valve 60 can be designed as a solenoid valve that is electrically switchable. The switchover of the valve 60 between its two positions can be controlled by the evaluation device 32. Normally, the valve 60 is in the operation of the delivery unit 40 in the position in which the measuring tube 14 is connected to the delivery unit 40 and thus is filled with fuel up to the level lo, so that by the
Differenzdrucksensor 24 und die Auswerteeinrichtung 32 der aktuelle Füllstand h des Kraftstoffbehälters 10 ermittelt werden kann. In bestimmten Zeitabständen wird das Ventil 60 in seine andere Stellung umgeschaltet, um das Meßrohr 14 mit dem Kraftstoffbehälter 10 zu verbinden und eine Ermittlung des Ausgangssignals uo des Differenzdrucksensors 24 zu ermöglichen und somit die Nullpunktsdrift auszugleichen. Diese Umschaltung des Ventils 60 kann nicht nur beim Stillstand der Brennkraftmaschine 46 bei abgeschaltetem Förderaggregat 40 erfolgen, sondern auch während des Betriebs des Förderaggregats 40.Differential pressure sensor 24 and the evaluation device 32, the current fill level h of the fuel tank 10 can be determined. At certain intervals, the valve 60 is switched to its other position in order to connect the measuring tube 14 to the fuel tank 10 and to determine the output signal uo of the differential pressure sensor 24 and thus to compensate for the zero point drift. This switchover of the valve 60 can not only take place when the internal combustion engine 46 is switched off Conveyor unit 40 take place, but also during the operation of the conveyor unit 40th
Alternativ kann das Ventil 60 auch derart ausgebildet sein, daß durch dieses in seiner einen Stellung dieAlternatively, the valve 60 can also be designed in such a way that the one in this position
Kraftstoffleitung 54 freigegeben wird und in seiner anderen Stellung die Kraftstoffleitung 54 gesperrt wird. In diesem Fall ist wie beim ersten Ausführungsbeispiel in der Kraftstoffleitung 54 zwischen dem Ventil 60 und dem Meßrohr 14 oder im Bereich des unteren Endes 30 des Meßrohrs 14 eine Öffnung 14 vorgesehen, um ein Entleeren des Meßrohrs 14 zu ermöglichen. Fuel line 54 is released and the fuel line 54 is blocked in its other position. In this case, as in the first exemplary embodiment, an opening 14 is provided in the fuel line 54 between the valve 60 and the measuring tube 14 or in the region of the lower end 30 of the measuring tube 14 in order to enable the measuring tube 14 to be emptied.

Claims

Ansprüche Expectations
1. Füllstandsmeßvorrichtung für einen Kraftstoffbehälter eines Kraftfahrzeugs, mit einem im Kraftstoffbehälter (10) angeordneten Meßrohr (14) , das sich ausgehend vom Boden (16) des Kraftstoffbehälters (10) bis wenigstens zum maximalen Füllstand des Kraftstoffbehälters (10) erstreckt, mit einem Differenzdrucksensor (24) , der mit einem Meßeingang (26) mit dem unteren Ende (30) des Meßrohrs (14) verbunden ist und mit einem anderen Meßeingang (28) dem Flussigkeitsdruck am Boden (16) des Kraftstoffbehälters (10) außerhalb des Meßrohrs (14) ausgesetzt ist, wobei in das Meßrohr (14) Kraftstoff gefördert wird und das Meßrohr (14) eine mindestens in Höhe des maximalen Füllstands des Kraftstoffbehälterrs (10) angeordnete Überströmöffnung (22) aufweist, wobei das Meßrohr (14) bis auf den aktuellen Füllstand des Kraftstoffbehälters (10) entleerbar ist, und wobei die Füllstandsbestimmung in einer Auswerteeinrichtung (32) aus der Differenz der Ausgangssignale des Differenzdrucksensors (24) bei bis zur Überströmöffnung (22) kraftstoffgefülltem Meßrohr (14) und bei bis zum aktuellen Füllstand des Kraftstoffbehälters (10) entleertem Meßrohr (14) erfolgt, dadurch gekennzeichnet, daß im1. Level measuring device for a fuel tank of a motor vehicle, with a measuring tube (14) arranged in the fuel tank (10), which extends from the bottom (16) of the fuel tank (10) to at least the maximum fill level of the fuel tank (10) with a differential pressure sensor (24), which is connected to the lower end (30) of the measuring tube (14) by a measuring inlet (26) and by another measuring inlet (28) the liquid pressure at the bottom (16) of the fuel tank (10) outside the measuring tube (14 ) is exposed, fuel being conveyed into the measuring tube (14) and the measuring tube (14) having an overflow opening (22) arranged at least at the level of the maximum filling level of the fuel tank (10), the measuring tube (14) up to the current filling level of the fuel tank (10), and the level determination in an evaluation device (32) from the difference in the output signals of the difference Enzdrucksensors (24) when the measuring tube (14) is filled with fuel up to the overflow opening (22) and when the measuring tube (14) is empty until the current fill level of the fuel tank (10), characterized in that in
Kraftstoffbehälter (10) ein Förderaggregat (40) angeordnet ist, durch das Kraftstoff aus dem Kraftstoffbehälter (10) zur Einspritzanlage (44) der Brennkraftmaschine (46) des Kraftfahrzeugs gefördert wird, und daß das Meßrohr (14) durch einen Teilstrom des vom Förderaggregat (40) geförderten Kraftstoffs gefüllt wird.Fuel tank (10) is arranged a delivery unit (40) through which fuel from the fuel tank (10) to the injection system (44) of the internal combustion engine (46) of the motor vehicle is conveyed, and that the measuring tube (14) is filled by a partial flow of the fuel delivered by the delivery unit (40).
2. Füllstandsmeßvorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß das Förderaggregat (40) über eine gegenüber dessen Leitung (50) zur Einspritzanlage (44) gedrosselte Verbindung (54) Kraftstoff in das Meßrohr (14) fördert .2. Level measuring device according to claim 1, characterized in that the delivery unit (40) via a line (50) to the injection system (44) throttled connection (54) promotes fuel in the measuring tube (14).
3. Füllstandsmeßvorrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß durch das Förderaggregat (40) Kraftstoff in das Meßrohr (14) nahe dessen unterem Ende (30) gefördert wird.3. Level measuring device according to claim 1 or 2, characterized in that fuel is conveyed into the measuring tube (14) near its lower end (30) by the delivery unit (40).
4. Füllstandsmeßvorrichtung nach einem der Ansprüche 1 bis4. Level measuring device according to one of claims 1 to
3, dadurch gekennzeichnet, daß die Entleerung des Meßrohrs (14) auf den aktuellen Füllstand des Kraftstoffbehälters (10) durch Abströmung von Kraftstoff aus dem Meßrohr (14) durch das Förderaggregat (40) in den Kraftstoffbehälter (10) erfolgt.3, characterized in that the emptying of the measuring tube (14) to the current fill level of the fuel tank (10) by fuel flowing out of the measuring tube (14) through the delivery unit (40) into the fuel tank (10).
5. Füllstandsmeßvorrichtung nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß in der Verbindung (54) zwischen dem Förderaggregat (40) und dem Meßrohr (14) ein Ventil (60) angeordnet ist, das zwischen einer Stellung, in der das Meßrohr (14) über die Verbindung (54) mit dem Förderaggregat (40) verbunden ist, und einer Stellung, in der das Meßrohr (14) mit dem Kraf stoffbehälter (10) verbunden ist, umschaltbar ist.5. Level measuring device according to one of claims 1 to 3, characterized in that in the connection (54) between the delivery unit (40) and the measuring tube (14) a valve (60) is arranged between a position in which the measuring tube (14) via the connection (54) to the delivery unit (40), and a position in which the measuring tube (14) is connected to the fuel tank (10), can be switched.
6. Füllstandsmeßvorrichtutng nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß in der Verbindung (54) zwischen dem Förderaggregat (40) und dem Meßrohr (14) ein Ventil (60) angeordnet ist, das zwischen einer Stellung, in der das Meßrohr (14) über die Verbindung (54) mit dem Förderaggregat (40) verbunden ist, und einer Stellung, in der die Verbindung (54) gesperrt ist, umschaltbar ist.6. Füllstandsmeßvorrichtutng according to one of claims 1 to 3, characterized in that in the connection (54) between the conveyor unit (40) and the measuring tube (14) a valve (60) is arranged, which is between a position in which the measuring tube (14) via the connection (54) with the Conveyor unit (40) is connected, and a position in which the connection (54) is blocked can be switched.
7. Füllstandsmeßvorrichtung nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß die vom7. Level measuring device according to one of the preceding claims, characterized in that the
Förderaggregat (40) geförderte Kraftstoffmenge in Abhängigkeit vom aktuellen Kraftstoffmengenbedarf der Brennkraftmaschine (46) des Kraftfahrzeugs veränderbar ist.Delivery unit (40) delivered fuel quantity depending on the current fuel quantity requirement of the internal combustion engine (46) of the motor vehicle can be changed.
8. Füllstandsmeßvorrichtung nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß im Kraftstoffbehälter (10) ein Druckregler (45) angeordnet ist, der einen mit der Druckseite des Förderaggregats (40) verbundenen Einlaß, einen mit der Einspritzanlage (44) der Brennkraftmaschine (46) des Kraftfahrzeugs verbundenen Auslaß und einen in den Kraftstoffbehälter (10) mündenden Rücklauf aufweist. 8. Level measuring device according to one of claims 1 to 6, characterized in that in the fuel tank (10) a pressure regulator (45) is arranged, which is connected to the pressure side of the delivery unit (40) inlet, one with the injection system (44) of the internal combustion engine (46) of the motor vehicle connected outlet and has a return opening into the fuel tank (10).
EP98937410A 1997-12-11 1998-06-26 Level metering device for a fuel tank of a motor vehicle Withdrawn EP0966655A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19755056 1997-12-11
DE19755056A DE19755056A1 (en) 1997-12-11 1997-12-11 Level measuring device for a fuel tank of a motor vehicle
PCT/DE1998/001746 WO1999030115A1 (en) 1997-12-11 1998-06-26 Level metering device for a fuel tank of a motor vehicle

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EP0966655A1 true EP0966655A1 (en) 1999-12-29

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US (1) US6164325A (en)
EP (1) EP0966655A1 (en)
JP (1) JP2001511258A (en)
KR (1) KR20000070642A (en)
CN (1) CN1105295C (en)
BR (1) BR9807571A (en)
DE (1) DE19755056A1 (en)
WO (1) WO1999030115A1 (en)

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Publication number Publication date
WO1999030115A1 (en) 1999-06-17
CN1105295C (en) 2003-04-09
BR9807571A (en) 2000-02-01
DE19755056A1 (en) 1999-06-17
CN1247600A (en) 2000-03-15
US6164325A (en) 2000-12-26
JP2001511258A (en) 2001-08-07
KR20000070642A (en) 2000-11-25

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