EP0718861A1 - Elektrischer Sicherheitsschalter - Google Patents

Elektrischer Sicherheitsschalter Download PDF

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Publication number
EP0718861A1
EP0718861A1 EP95420340A EP95420340A EP0718861A1 EP 0718861 A1 EP0718861 A1 EP 0718861A1 EP 95420340 A EP95420340 A EP 95420340A EP 95420340 A EP95420340 A EP 95420340A EP 0718861 A1 EP0718861 A1 EP 0718861A1
Authority
EP
European Patent Office
Prior art keywords
pressure
magnet
fluid
annular magnet
safety switch
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
EP95420340A
Other languages
English (en)
French (fr)
Other versions
EP0718861B1 (de
Inventor
Jean Claude Buffet
Lionel Raut
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.)
BorgWarner Transmission Systems Monaco SAM
Original Assignee
Eaton SAM
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 Eaton SAM filed Critical Eaton SAM
Publication of EP0718861A1 publication Critical patent/EP0718861A1/de
Application granted granted Critical
Publication of EP0718861B1 publication Critical patent/EP0718861B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H35/00—Switches operated by change of a physical condition
    • H01H35/24—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow
    • H01H35/40—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by devices allowing continual flow of fluid, e.g. vane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H35/00—Switches operated by change of a physical condition
    • H01H35/24—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow
    • H01H35/34—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by diaphragm
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H36/00—Switches actuated by change of magnetic field or of electric field, e.g. by change of relative position of magnet and switch, by shielding
    • H01H36/0073—Switches actuated by change of magnetic field or of electric field, e.g. by change of relative position of magnet and switch, by shielding actuated by relative movement between two magnets

Definitions

  • the present invention relates to an electric safety switch, controlled from the pressure of a liquid or gaseous fluid.
  • This electric switch can be used in cleaning devices for carpets, rugs and floors, to protect the pumps of these devices in particular against the risks of operation without water.
  • FIG. 1 of the attached schematic drawing The principle of such an appliance, in particular designated as a "carpet washer”, is recalled in FIG. 1 of the attached schematic drawing.
  • the apparatus comprises a reservoir 1, containing a solution of water and detergent.
  • a pump 2 connected to the reservoir 1, allows the pressurization of the water and detergent solution, thus ensuring its displacement along a pipe 3 equipped with a manual tap 4, and leading to a diffuser or nozzle 5. Under the effect of the pressure generated by the pump 2, the nozzle 5 diffuses the solution of water and detergent on the carpet or carpet to be cleaned, by forming a jet 6.
  • the pump 2 is actuated by a manual electric switch 7, placed on the device.
  • a safety pressure switch 8 can be arranged on the piping 3 at the outlet of the pump 2, to automatically control the stopping of the pump 2 in the case where the manual tap 4 is closed while the switch 7 supplies the pump electrically 2.
  • the principle illustrated in FIG. 1, and having just been recalled, has a major drawback residing in the fact that the pump 2 risks running continuously, as long as the manual switch 7 remains closed.
  • the pump 2 can operate without water if the tank 1 is empty, or at maximum pressure without water flow if the manual tap 4 is not opened by the user.
  • the pump 2 no longer cooled by the passage of liquid which also ensures the lubrication of its moving parts, is then quickly destroyed.
  • the present invention aims to remedy all of these drawbacks by providing an electrical safety switch which can replace the existing pressure switches mentioned above, which, while being of simplified manufacture, provides reinforced electrical insulation, and which, when applied to a carpet washer or similar device, is able to detect both the absence of liquid and the absence of flow in the appliance, even in the case where the normal operating pressure with a liquid is equal to that of the compressed air by the pump when the tank of the appliance is empty.
  • the invention essentially relates to an electric safety switch, controlled from the pressure of a liquid or gaseous fluid, which comprises a body with a passage for the liquid or gaseous fluid, a chamber in communication with the fluid passage, a movable and / or deformable element disposed inside the chamber and linked to an annular magnet, an electrically insulating and watertight partition which is surrounded by the annular magnet and which houses and guides a central magnet, axially movable and mechanically linked to a movable contact member, such as a contact blade, cooperating with at least one fixed electrical terminal so as to close or open an electrical circuit, depending on the position of the central magnet magnetically coupled to the coaxial annular magnet, itself positioned according to the pressure of the fluid admitted into the aforementioned chamber.
  • the proposed device thus uses two permanent magnets with coaxial arrangement, magnetically coupled and located on either side of an insulating partition, separating the part which is in contact with the fluid, such as water, from the part which comprises the electrical contacts of the switch.
  • the choice of an insulating separating partition of sufficient thickness makes it possible to obtain the “reinforced” electrical insulation which is desired.
  • the use of magnetically coupled permanent magnets ensures rapid switching between the closed and open positions of the switch, and an appropriate contact pressure in the closed position, without the need for springs, resulting in a significant constructive simplification.
  • the annular magnet is carried by a membrane flexible, immobilized by its periphery and delimiting a variable volume in which the fluid is admitted, the pressure of which is exerted on one face of the flexible membrane, this flexible membrane also being subjected to the effect of a return spring repelling it towards its rest position, that is to say the position it occupies for a minimum fluid pressure.
  • the flexible membrane is for example immobilized, by its periphery, between the aforementioned body and an insulating housing, comprising a cylindrical inner wall which is surrounded by the annular magnet, and which houses and guides the central magnet, the insulating housing carrying the electrical terminals which cooperate with the member such as a contact blade, moved by the central magnet.
  • the corresponding end faces of the central magnet and of the annular magnet that is to say their respective faces turned on the same side have identical polarities, so that the displacement of the annular magnet in one direction or the other, as a function of the fluid pressure, is accompanied by the effect of magnetic repulsion of displacements of opposite direction of the central magnet, therefore of the movable contact member such as contact blade.
  • the application of the phenomenon of magnetic repulsion, acting between the poles of the two coaxial magnets allows here a rapid tilting, from the closed position to the open position of the switch and vice versa, without the need for a spring, the magnetic repulsion force also ensuring, in the closed position of the switch, the pressure of the electrical contacts.
  • the passage of fluid from the body of the switch comprises, between its inlet and its outlet, a venturi, the neck of which communicates with the chamber in which the movable and / or deformable element is placed. to the ring magnet.
  • a switch provided with this latter arrangement is especially usable in a device of the carpet washer type, in as a protection switch for a pump for pressurizing a solution of water and detergent drawn from a tank.
  • the safety switch object of the invention here advantageously replaces the conventional pressure switches.
  • carpet washers generally have a dynamic pressure of water solution and detergent, in normal operation, which is substantially equal to that of the compressed air by the pump when the tank is empty and the manual tap is closed.
  • an ordinary pressure switch calibrated to a pressure close to that of the liquid in normal operation, under penalty of seeing it interrupt the electrical supply to the pump in normal operation.
  • the safety switch object of the present invention incorporating a venturi, provides a solution to this problem by reacting in a different way for two fluid pressures of the same size, depending on whether it is a liquid or d '' a gas, especially water or air. This results from the fact that the venturi creates a higher vacuum in the presence of a water flow.
  • the safety switch object of the invention can thus be adjusted to open its electrical contact at a pressure equal to those present in the hydraulic circuit in the presence of water or air, but it does not react unless the pressure of air reaches this particular value, which corresponds to a lack of water (empty tank).
  • the switch also cuts off the electrical supply to the pump in the event of high water pressure without flow, rendering the venturi ineffective (case where the manual tap remained closed).
  • the electric safety switch represented in FIG. 2, generally designated by the reference 8, comprises a housing 9 made of electrically insulating material, mounted on a body 10 in which is formed a fluid passage 11, extending between a fluid inlet 12 and fluid outlet 13.
  • the insulating housing 9 forms a cavity 14, closed on all sides.
  • Two electrical connection terminals 15 and 16 pass through the outer wall 17 of the insulating housing 9 and protrude inside the cavity 14.
  • a movable contact blade 18, housed inside the cavity 14, cooperates with the two terminals 15 and 16 so as to ensure either the passage of electric current between the two terminals 15 and 16, or the interruption of any electrical connection between these two terminals 15 and 16.
  • the cavity 14 is delimited by a cylindrical inner wall 19 of the insulating housing 9, which houses and guides a cylindrical central magnet 20, axially movable.
  • the contact blade 18 is mechanically linked to the central magnet 20, by means of a connecting rod 21, so as to receive the axial movement of the central magnet 20.
  • the chamber 22 communicates, through a channel 23, with the fluid passage 11 of the body 10.
  • a flexible membrane 24 Inside the chamber 22 is arranged a flexible membrane 24, the periphery of which is trapped between the insulating housing 9 and the body 10, in the joint plane of these two elements.
  • the movable internal part of the flexible membrane 24 carries an annular magnet 25, which takes place around the cylindrical interior wall 19 of the insulating housing 9, coaxially with the interior magnet 20.
  • the flexible membrane 24 has a helical spring 26, also housed in the chamber 22, which recalls the membrane 24 in the rest position, that is to say in the position close to the body 10.
  • the cylindrical inner magnet 20 and the annular outer magnet 25, arranged coaxially, are axially polarized.
  • their respective poles of the same name are located on the same side.
  • the N pole of the central cylindrical magnet 20 is located on its upper circular face
  • the N pole of the outer annular magnet 25 is located on its upper annular face
  • the S pole of the central cylindrical magnet 20 then being located on its lower circular face
  • the pole S of the annular outer magnet 25 is located on the lower annular face of the latter.
  • the assembly of the two magnets 20 and 25 therefore operates by magnetic repulsion, the poles of the same name (N or S) repelling each other.
  • the flexible membrane 24 In the rest position, the flexible membrane 24 is pushed back into its low position by the spring 26. As shown in the central part of FIG. 3, the annular outer magnet 25 then occupies its low position, and it pushes the central magnet 20 upwards, which has the effect of closing the electrical switch 8, the blade contact 18 being brought by the central magnet 20 to the simultaneous contact of the two terminals 15 and 16. In this closed position, the thrust F of the central magnet 20, directed upwards, ensures the contact pressure of the blade 18 on the two terminals 15 and 16.
  • the opening of the electrical switch 8 thus provoked interrupts the electrical supply, therefore the operation, of the pump 2 to be protected, electrically connected in series with this electrical safety switch 8 as well as with the manual electric switch 7, in an electric circuit branch 27 - see figure 4.
  • the fluid passage 11 of the body 10 preferably forms, between its inlet 12 and its outlet 13, a venturi with a converging 28, a neck 29 and a divergent 30, the channel 23 having its starting point at the level of the neck 29 of the venturi.
  • This venturi 28, 29, 30 creates, in the presence of water in the fluid passage 11, a depression in the chamber 22, at the level of the membrane 24, which is greater than the depression observed in the presence of air, thus bringing about a pressure difference between that of the air and that of the water contained in the piping 3 of the device.
  • the electrical switch 8 causes the pump 2 to stop only in the case where only air is present in the fluid passage 11, which corresponds to a lack of water necessitating the stopping of the pump 2.
  • the electric switch 8 does not "see" the real pressure of the water in normal operation, since a difference in pressure ⁇ P is created between the output of pump 2 and the pressure tapping point via channel 23, this pressure difference ⁇ P bringing the pressure in chamber 22 to a value lower than the setting pressure of switch 8.
  • FIG. 5 makes it possible to better appreciate the operation in pressure of the carpet washer, by indicating as a function of time t, the water pressure P1 in normal use, the water pressure P2 when the manual tap 4 is closed, and the air pressure P3 when the tank 1 is empty, this air pressure P3 being close to the water pressure P1 in normal use, itself lower than the maximum water pressure P2 usually observed when the manual tap 4 is closed.
  • This water pressure P2 is eliminated by virtue of the electrical safety switch 8 which is the subject of the invention, which controls the immediate stopping of the pump 2 in the event of such pressure appearing.
EP95420340A 1994-12-06 1995-12-01 Elektrischer Sicherheitsschalter Expired - Lifetime EP0718861B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9414886A FR2727787B1 (fr) 1994-12-06 1994-12-06 Interrupteur electrique de securite
FR9414886 1994-12-06

Publications (2)

Publication Number Publication Date
EP0718861A1 true EP0718861A1 (de) 1996-06-26
EP0718861B1 EP0718861B1 (de) 1999-02-03

Family

ID=9469676

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95420340A Expired - Lifetime EP0718861B1 (de) 1994-12-06 1995-12-01 Elektrischer Sicherheitsschalter

Country Status (4)

Country Link
US (1) US5703552A (de)
EP (1) EP0718861B1 (de)
DE (1) DE69507682D1 (de)
FR (1) FR2727787B1 (de)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5939638A (en) * 1997-08-01 1999-08-17 Zovath; Peter J. Pressure sensor with protective internal wall
JP3850199B2 (ja) * 2000-03-10 2006-11-29 ナイルス株式会社 インヒビタスイッチ
US6868732B2 (en) * 2002-09-25 2005-03-22 Siemens Vdo Automotive Inc. Differential pressure signaling device and method employing a magnetoresistive sensor
US7247210B2 (en) 2004-02-23 2007-07-24 Ecolab Inc. Methods for treating CIP equipment and equipment for treating CIP equipment
US7392811B2 (en) 2004-02-23 2008-07-01 Ecolab Inc. Delivery head for multiple phase treatment composition, vessel including a delivery head, and method for treating a vessel interior surface
US7220358B2 (en) 2004-02-23 2007-05-22 Ecolab Inc. Methods for treating membranes and separation facilities and membrane treatment composition
US7157653B1 (en) 2005-09-20 2007-01-02 Deltrol Controls Magnetic latching switch
US20080257908A1 (en) * 2007-04-23 2008-10-23 Reelick Eugene A Liquid dispensing device
CA2671500C (en) * 2009-07-10 2011-05-24 Thomas Lemmer Pressure differential motor control system and method
US8393875B2 (en) * 2009-08-20 2013-03-12 R. E. Prescott Co., Inc. Pressure-controlled liquid supply system and pump control device for use therein
CN101697331B (zh) * 2009-10-30 2013-04-17 福州斯狄渢电热水器有限公司 水流启动开关装置
US8528355B2 (en) * 2010-03-24 2013-09-10 Whirlpool Corporation Atomization unit with negative pressure actuator
US20110236544A1 (en) * 2010-03-24 2011-09-29 Whirlpool Corporation Atomization of food preservation solutions
CN106504941B (zh) * 2016-12-27 2018-10-09 中山市博安泰电器科技有限公司 一种差压开关
CN112951678A (zh) * 2021-02-05 2021-06-11 西安交通大学 基于磁场触发的液态金属限流器及其限流方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2412054A1 (de) * 1974-03-11 1975-09-25 Butzke Werke Ag Differenzdruck-schaltarmatur fuer fluessige oder gasfoermige medien
JPS63195395A (ja) * 1987-02-09 1988-08-12 Hitachi Ltd 自動式電動ポンプ
DE9405685U1 (de) * 1994-04-06 1994-05-26 Mann & Hummel Filter Differenzdruckschalter

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Publication number Priority date Publication date Assignee Title
DE9013153U1 (de) * 1990-09-15 1990-12-20 Pierburg Gmbh, 4040 Neuss, De
US5308939A (en) * 1992-07-21 1994-05-03 Fuji Koki Manufacturing Co., Ltd. Pressure equalizing mechanism for a pressure switch
JPH0652761A (ja) * 1992-08-01 1994-02-25 Mitsubishi Electric Corp 開閉器
US5425396A (en) * 1993-07-02 1995-06-20 Wodeslavsky; Josef Water pressure level control valve

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2412054A1 (de) * 1974-03-11 1975-09-25 Butzke Werke Ag Differenzdruck-schaltarmatur fuer fluessige oder gasfoermige medien
JPS63195395A (ja) * 1987-02-09 1988-08-12 Hitachi Ltd 自動式電動ポンプ
DE9405685U1 (de) * 1994-04-06 1994-05-26 Mann & Hummel Filter Differenzdruckschalter

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
"PRESSURE SWITCH FOR FUEL VAPOR", RESEARCH DISCLOSURE, no. 327, 1 July 1991 (1991-07-01), EMSWORTH,GB, pages 539 *
PATENT ABSTRACTS OF JAPAN vol. 012, no. 475 (M - 774) 13 December 1988 (1988-12-13) *

Also Published As

Publication number Publication date
DE69507682D1 (de) 1999-03-18
FR2727787B1 (fr) 1997-01-24
US5703552A (en) 1997-12-30
EP0718861B1 (de) 1999-02-03
FR2727787A1 (fr) 1996-06-07

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