EP0347904B1 - Mehrfach-Druckschalter - Google Patents

Mehrfach-Druckschalter Download PDF

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Publication number
EP0347904B1
EP0347904B1 EP89111369A EP89111369A EP0347904B1 EP 0347904 B1 EP0347904 B1 EP 0347904B1 EP 89111369 A EP89111369 A EP 89111369A EP 89111369 A EP89111369 A EP 89111369A EP 0347904 B1 EP0347904 B1 EP 0347904B1
Authority
EP
European Patent Office
Prior art keywords
switches
switch
support plate
diaphragm
membrane
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 - Lifetime
Application number
EP89111369A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0347904A2 (de
EP0347904A3 (de
Inventor
Helmut Dr. Dipl.-Phys. Baader
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.)
Elektromanufaktur Zangenstein Hanauer GmbH and Co KGaA
Original Assignee
Elektromanufaktur Zangenstein Hanauer GmbH and Co KGaA
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 Elektromanufaktur Zangenstein Hanauer GmbH and Co KGaA filed Critical Elektromanufaktur Zangenstein Hanauer GmbH and Co KGaA
Publication of EP0347904A2 publication Critical patent/EP0347904A2/de
Publication of EP0347904A3 publication Critical patent/EP0347904A3/de
Application granted granted Critical
Publication of EP0347904B1 publication Critical patent/EP0347904B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • H01H35/26—Details
    • H01H35/2657—Details with different switches operated at substantially different pressures
    • H01H35/2664—Details with different switches operated at substantially different pressures making use of a balance plate pivoting about different axes

Definitions

  • Membrane-operated switch arrangements in which two or more switches, in particular pretensioned mechanical snap switches, are actuated for electrical signals or load currents as a function of a pressure acting on the membrane, have numerous practical uses for controlling and regulating devices, for example washing machines and dishwashers.
  • the membrane is loaded with a pressure that is derived from the water level in the working area of the device.
  • Multiple pressure switches contain two or three switches in one housing, which are actuated by a common membrane.
  • EP-B-0026449 discloses a multiple pressure switch of the type described at the outset, in which the support plate is supported on a power transmission lever which in turn is tiltably supported at the coupling points of the switch.
  • a mandrel is arranged centrally on the support plate, which engages on all sides in a central, pan-like depression of the power transmission lever. This has three arms and has a claw at the ends of its arms, each of which rests on the coupling point of a switch.
  • the generated membrane force is distributed to the individual switches in equal or in different parts.
  • the switch-on and switch-back pressure values of the individual switches in a multiple pressure switch can be adapted within wide limits to the requirements of the respective application by suitable selection of the spring preloads and spring rates of the switches. Because of the properties of the membranes used, problems arise in these systems when two switches which are actuated by a common membrane are to switch at approximately or exactly the same actuation pressure, that is to say have the same switch-on points and / or the same switch-back points.
  • the multiple pressure switch shown in FIGS. 1 and 2 has a cup-shaped housing 10 with a circular housing edge 12.
  • the housing 10 is closed according to FIG. 2 by a membrane 14, which is not shown in FIG To release the interior of the housing 10.
  • the membrane 14 consists of an elastomer and is generally circular in the usual way. It has a bead-like edge 16, which serves to fasten the membrane 14 and, at the same time, when it is clamped between the housing 10 and a cover (not shown) for sealing to the outside.
  • a central field 18 of the membrane 14 is also preferably circular and is made of a relatively thick material.
  • the edge 16 and the central field 18 of the membrane 14 are connected to one another by an annular roll fold 20 made of very thin material.
  • the middle field 18 is supported by a rigid support plate 22.
  • This has in its center as a mostly integral component a power transmission mandrel 24 which engages in a conical recess 26 of a power transmission lever 28, so that a full gimbal mobility between the membrane 14 and the power transmission lever 28 is made possible.
  • the power transmission lever 28 is three-armed in the example shown and has a claw 30 or 30 'or 30' at the end of each of its arms. Each of these claws 30, 30 'and 30 ⁇ presses in a coupling point 32 or 32' or 32 ⁇ on an operating lever 34 or 34 'or 34 ⁇ of a switch 36 or 36' or 36 ⁇ .
  • the first is flat, so that it is tiltable and displaceable relative to the associated coupling point 32.
  • the other two claws 30 'and 30 ⁇ are pan-shaped, so that they are only tiltable, but not displaceable, with respect to the associated coupling points 32' and 32 ⁇ .
  • the minimum pressure difference between the two switches 36 and 36 ' is increased in practice if, for example, from the application of the multiple pressure switch there is an imperative that the switch 36 must have switched before the switch 36' may switch .
  • the addition of a safety distance to the switching pressures is necessary, because when approaching the critical point - see the thought experiment above, a minimal increase in the switching force of the switch 36 or a decrease in the switching force of the switch 36 'over the course of the service life of the device would be sufficient to topple the switching sequence.
  • the object of the invention is to develop a membrane-operated multiple pressure switch so that the disadvantages of the prior art described, namely either the need to use an expensive the relay as an intermediate link between the pressure switch and the circuits controlled by it, or the risk of changing the switching sequence of two or more switches of the same housing of the multiple pressure switch.
  • FIGS. 1 and 2 the fully cardanic coupling shown in FIGS. 1 and 2 between the membrane 14 and the power transmission lever 28 in the center of gravity of the membrane 14 is replaced by a coupling via two hinge points.
  • the connecting line forms an articulated axis 38 which extends through the solder in the centroid 40 of the membrane 14 and extends parallel to the connecting line of the coupling points 32 and 32 'between the power transmission lever 28 and the two switches 36 and 36'.
  • the support plate 22 is a substantially flat sheet metal plate, from which the two mandrels 42 and 44 are punched out and bent at right angles.
  • the first is conical, so that the associated mandrel 42 is supported in it at a defined hinge point.
  • the second recess 48 is elongated in the direction of the hinge axis 38, so that punching tolerances between the two mandrels 42 and 44 do not lead to jamming.
  • Fig. 4 shows the multiple pressure switch with full lines in the rest position and dashed lines in the position which its parts assume after the switch 36 has been switched on. Since the diaphragm 14 is not fully gimbally coupled to the force transmission lever 28, but rather via the two described articulation points, the diaphragm 14 can only pivot about the joint axis 38 with respect to the force transmission lever 28. If the power transmission lever 28 pivots about an axis that is perpendicular to the hinge axis 38, then the diaphragm 14 is forced to carry out this pivoting.
  • the middle field 18 of the membrane 14 shifts slightly towards the switch 36 due to the height conditions and also decreases on the side of the switch 36 by the amount that the stroke of this switch 36 corresponds.
  • a prerequisite for this is a fixation between the membrane 14 and the support plate 22, which excludes mutual displacements.
  • two or more wart-like projections 50 are formed on the central field 18 of the membrane 14, which are each snapped into a hole in the support plate 22.
  • the roll fold 20 of the membrane 14 is deformed during the movement described so that the membrane effective area F of the part within the contact circle between the roll fold 20 and the imaginary contact plane, see above) is shifted towards the switch 36 '.
  • This is evident from the consideration of the position of the effective diameter D1 before the diaphragm 14 is deflected in relation to the effective diameter D2 after the switch 36 has been switched on.
  • the center of gravity 40 of the membrane 14 approaches the switch 36 ', so that after switching the switch 36 at a constant pressure p across the membrane 14, the part of the membrane force K which is due to the switch 36' despite the slightly reduced membrane effective area F increases when switching.
  • Blocking the switch 36 'in a further experiment with a mechanical aid increases the pressure p across the membrane 14 until the switch 36 is switched, after switching the switch 36 reduces the pressure p again to a value at which this Switch 36 does not switch back yet, then releases the blockage of switch 36 'and increases the membrane pressure again, then it turns out that switch 36' switches at a pressure which (by about 100 Pascal with a membrane effective area of 28 cm2) below Pressure is at which the switch 36 has switched.
  • the pressure p on the diaphragm 14 (which is a measure of the water level reached in the machine) does not decrease when the first switch 36 is switched, so that after the diaphragm 14 has shifted its center of gravity, the second switch 36 ' , the response pressure of which is now lower, as described above, certainly switches.
  • the articulated connection between the power transmission lever 28 and the membrane 14, which allows the two parts to tilt against each other only about the hinge axis 38, is of great advantage for the quality of the coupling achieved between the two switches 36 and 36 '. If you couple the power transmission lever 28 rigidly to the support plate 22 or if you execute these two parts in one piece, then no coupling between the switches 36 and 36 'can be achieved with triple switches, which fully corresponds to the one described above. The reason for this is that with a rigid coupling, the membrane 14 tilts when switching the switch 36 about an axis, the connecting line of the coupling points 32 'and 32' between the power transmission lever 28 and the switches 36 'and Corresponds to 36 ⁇ .
  • the area center of gravity 40 of the active membrane surface F moves in the direction of the perpendicular to the tilt axis towards this, so that thereby the gain of the membrane force K is distributed to the switches 36 'and 36'.
  • the increase in the share of the total membrane force K due to the switch 36 'no longer fully compensates for the reduction in the effective membrane area F, so that the desired strong coupling in the switching behavior between the switches 36 and 36' is no longer achieved.
  • the support plate 22 and the power transmission lever 28 or the support plate 22 and the membrane 14 are not rigidly connected to one another, then the relevant parts slide parallel to the surface of the support plate 22 when the switch 36 is switched; as a result, the midfield 18 does not shift toward the switch 36.

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Switches Operated By Changes In Physical Conditions (AREA)
  • Invalid Beds And Related Equipment (AREA)
  • Push-Button Switches (AREA)
EP89111369A 1988-06-24 1989-06-22 Mehrfach-Druckschalter Expired - Lifetime EP0347904B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3821425A DE3821425C1 (es) 1988-06-24 1988-06-24
DE3821425 1988-06-24

Publications (3)

Publication Number Publication Date
EP0347904A2 EP0347904A2 (de) 1989-12-27
EP0347904A3 EP0347904A3 (de) 1991-04-10
EP0347904B1 true EP0347904B1 (de) 1992-09-02

Family

ID=6357214

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89111369A Expired - Lifetime EP0347904B1 (de) 1988-06-24 1989-06-22 Mehrfach-Druckschalter

Country Status (3)

Country Link
EP (1) EP0347904B1 (es)
DE (2) DE3821425C1 (es)
ES (1) ES2034514T3 (es)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19610254C1 (de) * 1996-03-15 1997-05-28 Zangenstein Elektro Druckschalter
US5796056A (en) * 1994-01-19 1998-08-18 Nbb Nachrichtentechnik Gmbh & Co. Kg Multi-stage switch

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4137115A1 (de) * 1991-11-12 1993-05-13 Dieter Dipl Ing Fleischer Tastatur
DE19637607A1 (de) * 1996-09-16 1998-03-19 Trw Fahrzeugelektrik Druckschalteinrichtung, insbesondere für die Kraftfahrzeugtechnik
DE102004041403B3 (de) * 2004-08-26 2005-11-24 Elektromanufaktur Zangenstein Hanauer Gmbh & Co. Kgaa Baueinheitlich integrierte Druckschalter- und Druckerfassungsvorrichtung

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1590361A1 (de) * 1965-09-30 1970-04-16 Elbi S A S Dei Flii Bianco Elektrischer Membran-Druckschalter
DE2938960A1 (de) * 1979-09-26 1981-04-09 Elektromanufaktur Zangenstein Hanauer Gmbh & Co, 8471 Zangenstein Mehrfach-druckschalter

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5796056A (en) * 1994-01-19 1998-08-18 Nbb Nachrichtentechnik Gmbh & Co. Kg Multi-stage switch
DE19610254C1 (de) * 1996-03-15 1997-05-28 Zangenstein Elektro Druckschalter
EP0795884A2 (de) * 1996-03-15 1997-09-17 ELEKTROMANUFAKTUR ZANGENSTEIN HANAUER GmbH & Co. Druckschalter
EP0795884A3 (de) * 1996-03-15 1998-09-30 ELEKTROMANUFAKTUR ZANGENSTEIN HANAUER GmbH & Co. Druckschalter

Also Published As

Publication number Publication date
DE58902189D1 (de) 1992-10-08
ES2034514T3 (es) 1993-04-01
DE3821425C1 (es) 1989-06-08
EP0347904A2 (de) 1989-12-27
EP0347904A3 (de) 1991-04-10

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