EP0000680B1 - Indicateur de niveau d'un liquide contenu dans un réservoir - Google Patents

Indicateur de niveau d'un liquide contenu dans un réservoir Download PDF

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Publication number
EP0000680B1
EP0000680B1 EP78400061A EP78400061A EP0000680B1 EP 0000680 B1 EP0000680 B1 EP 0000680B1 EP 78400061 A EP78400061 A EP 78400061A EP 78400061 A EP78400061 A EP 78400061A EP 0000680 B1 EP0000680 B1 EP 0000680B1
Authority
EP
European Patent Office
Prior art keywords
level indicator
level
push rod
indicator according
chamber
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.)
Expired
Application number
EP78400061A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0000680A1 (fr
Inventor
Michel Verne
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.)
DBA SA
Original Assignee
DBA SA
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 DBA SA filed Critical DBA SA
Publication of EP0000680A1 publication Critical patent/EP0000680A1/fr
Application granted granted Critical
Publication of EP0000680B1 publication Critical patent/EP0000680B1/fr
Expired legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M11/00—Component parts, details or accessories, not provided for in, or of interest apart from, groups F01M1/00 - F01M9/00
    • F01M11/10—Indicating devices; Other safety devices
    • F01M11/12—Indicating devices; Other safety devices concerning lubricant level
    • 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
    • G01F23/16—Indicating, recording, or alarm devices being actuated by mechanical or fluid means, e.g. using gas, mercury, or a diaphragm as transmitting element, or by a column of liquid
    • G01F23/165—Indicating, recording, or alarm devices being actuated by mechanical or fluid means, e.g. using gas, mercury, or a diaphragm as transmitting element, or by a column of liquid of bubbler type
    • G01F23/168—Indicating, recording, or alarm devices being actuated by mechanical or fluid means, e.g. using gas, mercury, or a diaphragm as transmitting element, or by a column of liquid of bubbler type with electric indicating or recording
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches

Definitions

  • the invention relates to a liquid level indicator contained in a tank, the latter being constituted for example by the crankcase of the engine of a motor vehicle.
  • level indicators there are many types of level indicators, and it is known in particular from German Patent No. 1,249,550 a pneumatic level indication device comprising a gas pressure source communicating with a tubular probe immersed in the liquid and with an indicator manometer, this source of gas pressure comprising a housing which defines a chamber filled with gas and a heating resistance serving to increase the pressure which reigns there by heating of the gases, as well as a bistable device with abrupt action whose operation is controlled by this same resistor and has the effect of cyclically cutting and restoring its electrical supply circuit.
  • This bistable device also provides mechanical control of a valve for admitting cold gases into the chamber, while an exhaust valve allows hot and pressurized gases to reach the probe and the indicator pressure gauge.
  • the present invention aims to design a level indicator suitable for monitoring the effective level of liquid contained in the reservoir with respect to a minimum admissible level value, and for automatically actuating a warning system when the effective level drops below this minimum level.
  • this object is achieved by means of an apparatus comprising a tubular probe immersed in the liquid and emerging at a depth defining the minimum level of liquid in the reservoir, a source of gas pressure comprising a housing defining a chamber filled with gas communicating with the probe and a heating resistor included in said chamber and intended to increase the pressure which prevails there during the use of this source of gas pressure, and a bistable device with abrupt action including an electric heating element supplied by the same circuit as said heating resistor and designed to cycle this device cyclically from a closed position to an open position of the common supply circuit, and vice versa, following the implementation of the source of gas pressure, this apparatus being characterized in that the bistable device is further arranged so as to actuate a warning member when it is in the closed position, and in addition, a locking device is provided which responds to pressure variations inside the chamber by passing from a rest position to a locking position when this pressure comes to exceed a predetermined value thus indicating that the level of liquid in the reservoir is above the minimum allowable, said locking device
  • the bistable device comprises a movable contact cooperating in the closed position with a fixed contact so as to close the common supply circuit of said heating resistor and said heating element, and these contacts then simultaneously control the circuit actuation of the warning device.
  • a movable stop means is provided, the displacement of which, controlled by the locking device when the latter comes to occupy its locking position, has the effect of opposing the mutual engagement of said contacts.
  • the supply circuit for the heating resistor and the heating element and the actuation circuit for the Warning devices are parallel circuits which are both controlled by the vehicle's ignition key switch, and the warning device consists of a dashboard indicator light which is itself connected in series with the mano oil pressure contact.
  • this warning light which lights up continuously as soon as the ignition contact is established and goes out normally once the engine is started, lights up again flashing at the rate of operation of the bistable device in the event of 'insufficient oil level, thus clearly indicating this anomaly to the driver, without requiring the installation of any additional warning means.
  • the level indicator represented in FIGS. 1 and 2 comprises a probe designated by the general reference 10, a source of gas pressure designated by the general reference 12, a locking device designated by the general reference 14, and a warning system designated by the general reference 16.
  • the gas pressure source 12 comprises a housing 18 in which is defined a chamber filled with gas 20 which communicates with the probe 10 by a measurement orifice 22 formed in a tubular end piece 24 received in a sealed manner in a opening 26, of cylindrical section, formed in the upper wall 28 of the reservoir 30, shown only partially in the figures.
  • the reservoir 30 is constituted in the embodiment represented by the crankcase of the engine of a motor vehicle, the liquid whose level is to be monitored being the lubrication fluid 32 contained in this crankcase.
  • the gas pressure source 12 further comprises a heating resistor 34 disposed inside of the chamber 20 and supplied by an electric circuit comprising, inter alia, a DC voltage source 36 such as, for example, the vehicle's storage battery, and a switch 38 preferably constituted by the ignition key switch of the vehicle.
  • This electrical circuit further comprises a heating wire 40 and a bistable device 42 both disposed inside the chamber 20 and serving to close the circuit comprising the heating resistor 34 on an output terminal 44 connected to the vehicle ground, the heating resistor 34 being itself connected to the switch 38 by an input terminal 46.
  • One end of the heating wire 40 is fixed to a terminal 48 disposed inside the housing 18 and by which it is connected to the heating resistor 34, while the other end of the wire 40 is stressed in tension by a leaf spring 50, the opposite end of which is fixed to the housing 18 by a cover 52 also ensuring the fixing of the terminal 48 which is electrically insulated from the leaf 50 by an insulating element 54.
  • the rivet 52 also ensures the fixing in the housing 18 of a second output terminal 56 on which is pivotally mounted an arm 58 carrying a movable contact 60 capable of coming to engage a fixed contact 62 carried by the output terminal 44.
  • the pivoting of the arm 58 is controlled by a leaf spring 64 sensitive to the movement of the free end of the leaf spring 50, the latter itself being controlled by changes in length of the heating wire 40.
  • the bistable device 42 consists essentially of the movable contact 60 e t by the fixed contact 62 and it is disposed in its entirety inside the chamber 20. It will be noted that the movable contact 60 is permanently electrically connected to the output terminal 56.
  • the warning system 16 consists essentially of a warning device 66, for example by an indicator light or by any other similar device capable of being mounted on the dashboard of the vehicle. This warning member 66 is mounted between the input 46 and output 56 terminals so that it is actuated when the movable contact 60 engages the fixed contact 62, the ignition key switch 38 being also closed. .
  • the locking device 14 mainly comprises means forming a piston constituted by a membrane 68 and a pusher 70 which control the movements of a movable stop 72 on which can bear a block of ferrite 74 disposed at the end of the arm 58 carrying the movable contact 60 and whose role will appear in the following description.
  • the outer peripheral edges of the membrane 68 are pinched between a cover 76 and the wall of the housing 18 opposite the end piece 24 so that this membrane 68 defines with the housing 18 and the cover 76 a working chamber 78 which communicates with the chamber 20 through a passage 80 and a second chamber 82 which communicates with the atmosphere through an opening 84 and in which is disposed a spring 86 normally biasing the membrane 68 downwards considering the figures.
  • the pusher 70 is integral with the membrane 68 and passes through the wall of the housing 18 to cooperate with a tab 88 formed on the free end of an elastic blade which constitutes the movable stop 72 and the other end of which is fixed by any means suitable, such as, for example, by welding, at the output terminal 56.
  • the end of the pusher 70 disposed in the chamber 20 to cooperate with the tab 88 has a section of small diameter 90 and ends in a section of large diameter 92 in which is formed a groove 94 arranged in the vicinity of the section of small diameter 90, the parts of small diameter 90 and of large diameter 92 being connected by a frustoconical part 96 allowing the tab 88 to pass from the part of small diameter 90 to the large diameter portion 92 when the pusher 70 is urged upwards by considering the figures.
  • the end of the tab 88 is engaged in the groove 94, the elasticity of the elastic blade 72 normally prevents its escape so that the pusher 70 is then locked in its high position, such as shown in Figure 2.
  • a leakage passage defining a controlled pressure drop is also provided for permanently communicating the chamber 20 and the atmosphere so as to prevent the air trapped in the probe 10, preferably consisting of a tube 98, a beveled end 100 of which dips into the liquid 32, does not rise appreciably and irreversibly when the engine cools, which could have the consequence of giving the impression during the next measurement of a level of liquid 32 inside the crankcase 30 substantially higher than the actual level.
  • this leakage passage consists of a spiral-shaped groove 102 formed on the end piece 24 opposite a sealing washer 104 disposed between the latter and the rest of the housing 18.
  • the groove 102 opens on either side of the washer 104 and a passage 106 is also provided in the end piece 24 to put in communication the chamber defined inside the casing 30 above the liquid 32 with the groove 102 in the vicinity from its end opening into the supply orifice 22.
  • the oil pressure switch 108 of the vehicle is also mounted in series with the warning member 66 and the ignition key switch 38 to define a third electrical circuit, known per se. , allowing the warning member 66 to indicate whether the oil pressure inside the crankcase of the vehicle engine is correct before operating the latter and after closing the key switch contact.
  • the chamber 20 communicates directly via the tube 98 with the chamber defined above the liquid 32 inside the tank 30.
  • the heating of the air inside the chamber 20 by the resistor 34 which would normally have the consequence of increasing the pressure inside the chamber 20, is compensated by l exhaust of the air contained in the latter by the end of the tube 98.
  • the pressure prevailing inside the chamber 20 therefore remains substantially constant and in any case does not increase enough to raise the pusher 70 by the intermediate of the membrane 68.
  • the tab 88 of the elastic blade 72 therefore remains in abutment against the small diameter section 90 of the pusher 70.
  • the movable contact 60 is separated from the fixed contact 62.
  • the circuit comprising the heating resistor 34 and the heating wire 40 remains closed on the terminal 56 so that the heating resistor 34 and the heating wire 40 remain energized until the vehicle engine is started.
  • the heating wire 40 therefore keeps its extended position which makes it possible to maintain the movable contact 60 in the standby position.
  • the heating of the air inside the chamber 20 due to the tensioning of the resistor 34 results in an increase in the pressure prevailing inside this chamber, since the air does not immediately escape through the end of the tube 98 as in the previous case, but must discharge the liquid contained therein, which leads to an increase in pressure inside the chamber 20 whose value is as a function of the depth of the tube 98 which is immersed in the liquid 32.
  • the pressure prevailing inside the chamber 20 and communicated by the orifice 80 inside the control chamber 78 becomes sufficient to lift the membrane 68 against the spring 86, so that the tab 88 of the elastic blade 72 engages in the groove 94 formed in the large diameter portion 92 of the pusher 70.
  • the force exerted by the blade elastic 72 is then sufficient to hold the pusher 70 in the position shown in Figure 2, against the spring 86, regardless of the pressure then prevailing in the chamber 78.
  • the electrical circuit comprising the heating resistor 34 and the heating wire 40 is no longer supplied, which results in the shortening of the heating wire 40 tending to return the arm 58 to the position it occupies in solid lines on the Figure 1.
  • the elastic blade 72 then constitutes a stop against which the end of the arm 58 comes to bear via the ferrite block 74.
  • the movable contact 60 can therefore not come into engagement with the fixed contact 62, so that the back and forth cycle of the arm 58 described with reference to FIG. 1 cannot occur and only the shutdown of the member warning 66 resulting from opening the mano -contact 108 is not called into question.
  • the device which has just been described therefore makes it possible both to provide an indication of the oil pressure value inside the engine of the vehicle by continuous actuation of the warning member 66, and to indicate a possible insufficiency of liquid level inside the reservoir 30 when the engine is started by a cyclic actuation of the warning member 66, easy to distinguish from its continuous actuation serving in a known manner for verification pressure.
  • a motor vehicle as regards its structure which can be modified substantially, a pressure source of the type of the pressure source 12 can for example be placed at a location relatively distant from the tank whose level is to be monitored .

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
  • Lubrication Details And Ventilation Of Internal Combustion Engines (AREA)
EP78400061A 1977-07-26 1978-07-20 Indicateur de niveau d'un liquide contenu dans un réservoir Expired EP0000680B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7722955A FR2399010A1 (fr) 1977-07-26 1977-07-26 Indicateur de niveau d'un liquide contenu dans un reservoir
FR7722955 1977-07-26

Publications (2)

Publication Number Publication Date
EP0000680A1 EP0000680A1 (fr) 1979-02-07
EP0000680B1 true EP0000680B1 (fr) 1980-01-09

Family

ID=9193830

Family Applications (1)

Application Number Title Priority Date Filing Date
EP78400061A Expired EP0000680B1 (fr) 1977-07-26 1978-07-20 Indicateur de niveau d'un liquide contenu dans un réservoir

Country Status (7)

Country Link
US (1) US4204203A (it)
EP (1) EP0000680B1 (it)
JP (1) JPS5424667A (it)
DE (1) DE2857517D1 (it)
ES (1) ES472042A1 (it)
FR (1) FR2399010A1 (it)
IT (1) IT1097369B (it)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4754732A (en) * 1987-02-12 1988-07-05 Tecumseh Products Company Low oil sensor for an internal combustion engine
DE3881394T2 (de) * 1988-11-05 1993-09-09 Able Corp Detektion der oberflaeche einer fluessigkeit oder schaumschicht.
US5059954A (en) * 1990-12-21 1991-10-22 Knight Equipment Corp. Liquid level sensing system

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3132331A (en) * 1956-10-10 1964-05-05 King Seeley Thermos Co Fluid level signal system
DE1249550B (it) * 1966-07-20
US3739337A (en) * 1970-04-14 1973-06-12 Lucas Industries Ltd Fuel gauge operating circuits for road vehicles
FR2230980B1 (it) * 1973-05-22 1976-04-23 Stop Sa
FR2338483A1 (fr) * 1976-01-16 1977-08-12 Dba Indicateur de niveau d'un liquide contenu dans un reservoir

Also Published As

Publication number Publication date
IT7826069A0 (it) 1978-07-25
DE2857517D1 (en) 1980-02-14
IT1097369B (it) 1985-08-31
JPS5424667A (en) 1979-02-24
FR2399010B1 (it) 1980-04-04
ES472042A1 (es) 1979-05-01
EP0000680A1 (fr) 1979-02-07
FR2399010A1 (fr) 1979-02-23
US4204203A (en) 1980-05-20

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