US3465112A - Fluid pressure actuated diaphragm switch - Google Patents

Fluid pressure actuated diaphragm switch Download PDF

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Publication number
US3465112A
US3465112A US673604A US3465112DA US3465112A US 3465112 A US3465112 A US 3465112A US 673604 A US673604 A US 673604A US 3465112D A US3465112D A US 3465112DA US 3465112 A US3465112 A US 3465112A
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United States
Prior art keywords
diaphragm
housing
recess
switch
fluid
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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
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US673604A
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English (en)
Inventor
Ludwig Reichert
Werner Heinlein
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
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Publication of US3465112A publication Critical patent/US3465112A/en
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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
    • H01H35/34—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by diaphragm

Definitions

  • a fluid pressure actuated switch whose housing is provided with an internal annular recess for the marginal portion of an elastomeric semielastic diaphragm.whose central portion bulges into the pressure chamber, of the housing.
  • the pressure chamber is located opposite a second chamber which receives one or more contacts.
  • the present invention relates to improvements in fluid pressure actuated diaphragm switches.
  • German Patent No. 1,080,189 discloses a diaphragm switch whose housing accommodates a diaphragm having a marginal portion tightly clamped by a steel ring so that it undergoes axial compression.
  • the diaphragm divides the interior of the housing into a pressure chamber and a second chamber which accommodates one or more electric switch contacts.
  • the central portion of the diaphragm bulges into the pressure chamber and is deformed in response to admission of pressurized fluid to actuate the switch.
  • the steel ring cooperates with an internal shoulder of the housing to clamp the marginal portion of the diaphragm.
  • a serious drawback of such pressure responsive switches is that their parts must be machined and assembled with a high degree of precision which contributes to high initial cost and result in a large number of rejects.
  • the clamping action of the aforementioned ring must be selected with a view to prevent damage to the marginal portion of the diaphragm.
  • the interior of the housing must be machined with a high degree of precision to insure satisfactory bulging of the diaphragm and to avoid unevennesses on the aforementioned shoulder because the unevennesses could result in damage to the marginal portion of the diaphragm.
  • Another object of the invention is to provide a diaphragm switch which can operate properly even if its component parts are not machined or otherwise finished with a high degree of precision.
  • a further object of the invention is to provide a diaphragm switch wherein the marginal portion of the diaphragm need not be clamped in the housing but the diaphragm is still capable of preventing escape of fluid from the pressure chamber.
  • An additional object of our invention is to provide a diaphragm switch wherein the diaphragm may be installed in the housing in a novel and time-saving way.
  • a fluid pressure actuated electric switch which comprises a housing having an internal surface provided with an annular recess of predetermined axial length or width, a deformable diaphragm inserted into the housing and having a marginal portion received in the recess whereby the interior of the housing is divided into a pressure chamber and a second chamber or switch contact chamber, the marginal portion of the diaphragm having a thickness which is less than or at most equals the width of the recess and the diaphragm further having a central portion which bulges into the pressure chamber, and a nipple or analogous means for admitting into the pressure chamber a gaseous or liquid pressure fluid to stress the diaphragm with resulting thickening of the marginal portion whereby the latter provides a fluid-tight seal between the two chambers.
  • the central portion of the diaphragm flattens out in response to admission of fluid into the pressure chamber so that the diaphragm tends to expand radially with
  • the housing is preferably provided with an apertured partition located in the second chamber to constitute a back support for the central portion during admission of fluid into the pressure chamber.
  • the partition can slidably guide a trip in the form of a plug or rivet which causes opening or closing of the switch in response to admission of fluid into the pressure chamber.
  • the trip is preferably biased against the central portion of the diaphragm by a suitable spring installed in the second chamber.
  • FIG. 1 is a partly elevational and partly axial sectional view of a fluid pressure actuated diaphragm switch which embodies one form of our invention, the diaphragm being shown in unstressed condition;
  • FIG. 2 is a similar view of the switch but showing the diaphragm in stressed condition
  • FIG. 3 is an axial sectional view of the diaphragm as it appears prior to insertion into the housing of the switch;
  • FIG. 4 is an axial sectional view of a second diaphragm
  • FIG. 5 is an axial sectional view of a third diaphragm.
  • FIG. 6 is a fragmentary axial sectional view of a housing which forms part of a modified switch.
  • the fluid pressure actuated diaphragm switch of FIG. 1 comprises a metallic housing or casing 1 having a lower portion 2 surrounding a pressure chamber or plenum chamber 3 for a pressurized fluid which can be admitted through an inlet here shown as a nipple 4 which is integral with the housing 1.
  • the discharge end of the central bore 5 in the inlet 4 is adjacent to the bulging central portion 8a of a disk-shaped diaphragm 8 whose marginal portion 8b extends into an annular recess or groove 7 provided in the internal surface of the housing 1.
  • the lower axial end of the recess 7 is bounded by an annular shoulder 6 of the housing 1.
  • the marginal portion 8b of the diaphragm 8 has a cylindrical peripheral surface 8' which is illustrated in FIG. 3, the latter showing the diaphragm as it appears prior to insertion into the housing 1.
  • the diaphragm consists of oil-resistant elastic material, preferably rubber or synthetic plastic, and is produced by injection molding.
  • the diameter of the recess 7 is smaller than the diameter of the peripheral surface 8' in unstressed condition of the diaphragm.
  • the upper axial end of the recess 7 is bounded by a radially outwardly extending shoulder 9 of the housing 1 which serves as a seat for a disk-shaped partition 10 constituting a back support for the central portion 8a of the diaphragm 8 when the latter is stressed in response to admission of a gaseous or liquid fluid through the bore of the inlet 4.
  • the partition is received in a second annular recess 11 of the housing 1 which is adjacent to and whose diameter is larger than that of the recess 7.
  • the axial length or width of the recess 7 (between the shoulders 6 and 9) is slightly greater than the thickness of the marginal portion 8b of the diaphragm 8.
  • the width of the recess 7 may exceed the thickness of the marginal portion 8b by one or more tenths of a millimeter, preferably no more than one millimeter. Since the diameter of the peripheral surface 8' exceeds the diameter of the recess 7, the diaphragm 8 is deformed in response to insertion into the housing 1 and its central portion 8a bulges away from the partition 10, i.e., into the pressure chamber 3. In other words, the material of the marginal portion 8b of the diaphragm 8 is forced from all sides toward the center of the diaphragm. The space between the downwardly bulging central portion 8a and the underside of the partition 10 (as viewed in FIG.
  • the head 14 of a reciprocable rivetshaped trip 13 whose stem 15 extends through a central aperture 16 of the partition and whose disk-shaped upper end 14a extends into a second chamber 17 of the housing 1.
  • the head 14 bears against the concave side of the central portion 8a of the diaphragm 8 and the disk-shaped upper end 14:: is biased downwardly by a helical return spring 14b accommodated in the chamber 17.
  • the end portion 14a can complete an electric circuit between two electric contacts 17a, 17b in the second chamber 17 or it can move these contacts upwardly to thereby open or close the switch.
  • the numeral 12 denotes an annular bead which overlies the upper side of the partition 10 and is formed by upsetting a portion of the housing 1 above the second recess 11. This bead 12 holds the partition 10 in the illustrated position and permanently locks the diaphragm 8 in the space below the partition.
  • FIG. 1 illustrates the switch in inoperative position, i.e., when the diaphragm 8 is unstressed because the bore '5 of the inlet 4 is sealed or disconnected from a source of pressurized fluid.
  • the central portion 8a of the diaphragm 8 is stressed and undergoes deformation in a manner as shown in FIG. 2.
  • the bulge of the central portion 8a is reduced and a larger part of this central portion bears against the underside of the partition 10.
  • the thickness of the marginal portion 8b of the diaphragm 8 increases in response to flattening of the central portion 8a whereby the marginal portion completely fills the recess 7 and provides a fluidtight seal between the chambers 3 and 17.
  • the thickness of the marginal portion 8b of the diaphragm 8 then equals the axial distance between the shoulders 6 and 9, and such thickening takes place in response to relatively small flattening of the central portion 8a.
  • the marginal portion 8b is then tightly clamped between the shoulder 6 and partition 10, and such clamping or sealing action improves in response to increasing fluid pressure in the chamber 3, namely, in response to progressing flattening of the central portion 8a. It was found during actual testing that the diaphragm 8 can readily withstand extremely high pressures in the range of atmospheres above atmospheric pressure without any leakage of fluid into the chamber 17. When the diaphragm 8 is stressed in a manner as shown in FIG.
  • the central portion 8a displaces the trip 13 whereby the upper end portion 14a of the trip engages the contacts 17a, 17b and thus actuates the switch, for example, by moving the contacts upwardly.
  • the stem 15 is guided in the aperture 16 so that it prevents tilting of the trip 13. If the pressure of fluid in the chamber 3 drops, the diaphragm 8 reassumes its unstressed or normal condition and its central portion 8a again assumes the shape shown in FIG. 1. In the absence of the spring 14b, the trip 13 moves downwardly by gravity and is disengaged from the contacts 17a, 17b. If the contacts 17a, 17b are movable with reference to the housing 1, they also return to their normal positions as soon as the fluid pressure upon the diaphragm 8 is relaxed sufficiently to permit more pronounced bulging of the central portion 80.
  • FIG. 4 illustrates in section a second diaphragm 18 whose central portion 19 bulges prior to insertion into the housing 1.
  • the diameter of this diaphragm 18 need not exceed the diameter of the recess 7.
  • the bulge of the central portion 19 can be produced in a number of ways, for example, during injection molding or by deformation in response to localized heating.
  • the thickness of the marginal portion 18a of the diaphragm 18 is less than or at most equals the width of the recess 7.
  • the thickness of this marginal portion 18a may but need not be the same as the thickness of the central portion 19.
  • the stressing of diaphragm 18 takes place in the same way as described in connection with FIG. 2 and the marginal portion 18a becomes thicker to provide a reliable seal between the pressure chamber and the second chamber.
  • the diameter of the diaphragm 18 may exceed the diameter of the recess 7 so that the diaphragm undergoes at least some deformation and the bulge of its central portion 19 increases in response to insertion into the switch housing. This also insures that the diaphragm seals the pressure chamber from the second chamber at all times, i.e., also when the inlet is disconnected from a source of pressurized fluid so that the fluid pressure in pressure chamber is the same as that in the second chamber.
  • FIG. 5 illustrates a further diaphragm 20 which also resembles a flat disk and has a conical peripheral surface 20' composed of two conical portions which taper away from the respective axial ends.
  • An advantage of the diaphragm 20 is that its marginal portion 20a can move into very satisfactory sealing engagement with the cylindrical or conical portion of the internal surface of a housing which surrounds the recess 7 or a similar recess.
  • the two conical parts of the marginal portion 20a can provide a very satisfactory sealing action prior to admission of a fluid into the pressure chamber and they allow for more rapid radial and axial deformation of the marginal portion 20a in response to admission of fluid into the pressure chamber.
  • the trip 13 or an analogous actuating device can operate the switch in response to a relatively small rise in fluid pressure in the pressure chamber. It was found that the diaphragm 20 of FIG. 5 is also very effective when the pressure chamber accommodates a fluid medium, i.e., that its sealing action is satisfactory not 'only in unstressed but also in stressed condition of the central portion.
  • FIG. 6 there is shown a modified switch housing 21 wherein the recess 22 is bounded by a conical portion of the internal surface of the housing.
  • This recess 22 tapers away from the bore 5' of the inlet 4'.
  • the partition is installed in a second recess in the same way as described in connection with FIG. 1.
  • the diaphragm has been omitted for the sake of clarity,
  • the conicity or taper of the recess 22 can be achieved by exerting upon the shoulder 9' of the housing 21 an axial pressure which reduces the diameter of the upper end of the recess 22.
  • This recess can accommodate any one of the diaphragms -8, 18 and 20 and the conical surface portion bounding the recess 22 insures a very satisfactorysealing action in unstressed and/ or stressed condition of the diaphragm.
  • the deformation or thickening of the marginal portion will begin in response to a relatively small fluid pressure, and the sealing action improves with increasing fluid pressure.
  • the shoulder 23 corresponds to the. shoulder 6 of FIG. 1 and the numeral 17' denotes a contactcontaining chamber at the upper side of the partition 10.
  • a combination comprising a housing having an internal surface provided with an annular recess of predetermined axial length and bounded by two axially spaced side faces and an annular bottom face having a predetermined diameter; a diaphragm consisting of elastomeric material, having a predetermined thickness and a predetermined diameter greater than the diameter of said annular bottom face, said diaphragm being inserted into said housing and having a circumferentially extended marginal portion received in said recess whereby the interior of said housing is divided into a pressure chamber and a second chamber, the thickness of said marginal portion being slightly smaller than said predetermined axial length of said recess and said diaphragm when inserted having a central portion bulging into said pressure chamber due to said predetermined diameter of said diaphragm which is greater than said predetermined diameter of said annular bottom face of said recess; and means for admitting into said pressure chamber a pressure fluid to compress said diaphragm with resulting radially out
  • said diaphragm is a flat disk whose diameter exceeds the diameter of said recess before said marginal portion is received in said recess.

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Switches Operated By Changes In Physical Conditions (AREA)
US673604A 1966-10-27 1967-10-09 Fluid pressure actuated diaphragm switch Expired - Lifetime US3465112A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEB0089592 1966-10-27

Publications (1)

Publication Number Publication Date
US3465112A true US3465112A (en) 1969-09-02

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US673604A Expired - Lifetime US3465112A (en) 1966-10-27 1967-10-09 Fluid pressure actuated diaphragm switch

Country Status (6)

Country Link
US (1) US3465112A (fr)
AT (1) AT278955B (fr)
DE (1) DE1590170A1 (fr)
FR (1) FR1535064A (fr)
GB (1) GB1196005A (fr)
SE (1) SE345338B (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3581034A (en) * 1968-06-12 1971-05-25 Bosch Gmbh Robert Fluid-pressure-actuated switch
US4456801A (en) * 1982-03-08 1984-06-26 The Singer Company Pressure switch
US4565920A (en) * 1984-05-14 1986-01-21 Temp. Systems, Inc. Fail safe thermal control device
US5461207A (en) * 1993-05-20 1995-10-24 Dwyer Precision, Inc. Hand held actuator for a patient call system
US20080171970A1 (en) * 2006-11-01 2008-07-17 Luzbetak Mark A Self returning contamination barrier

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3145348C2 (de) * 1981-11-14 1985-01-17 Doduco KG Dr. Eugen Dürrwächter, 7530 Pforzheim Hydraulisch betätigter Schalter

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2284424A (en) * 1940-05-31 1942-05-26 George N Hein Packing gland with oversize floating gasket
US2694415A (en) * 1950-12-23 1954-11-16 Watts Regulator Co Diaphragm construction for thermostats or motors
US2741678A (en) * 1952-04-09 1956-04-10 Square D Co Pressure switch
US3093716A (en) * 1961-01-23 1963-06-11 Berg Airlectro Products Co Snap action switch
US3218051A (en) * 1961-05-19 1965-11-16 Doetsch Hans Peter High pressure seals

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2284424A (en) * 1940-05-31 1942-05-26 George N Hein Packing gland with oversize floating gasket
US2694415A (en) * 1950-12-23 1954-11-16 Watts Regulator Co Diaphragm construction for thermostats or motors
US2741678A (en) * 1952-04-09 1956-04-10 Square D Co Pressure switch
US3093716A (en) * 1961-01-23 1963-06-11 Berg Airlectro Products Co Snap action switch
US3218051A (en) * 1961-05-19 1965-11-16 Doetsch Hans Peter High pressure seals

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3581034A (en) * 1968-06-12 1971-05-25 Bosch Gmbh Robert Fluid-pressure-actuated switch
US4456801A (en) * 1982-03-08 1984-06-26 The Singer Company Pressure switch
US4565920A (en) * 1984-05-14 1986-01-21 Temp. Systems, Inc. Fail safe thermal control device
US5461207A (en) * 1993-05-20 1995-10-24 Dwyer Precision, Inc. Hand held actuator for a patient call system
US20080171970A1 (en) * 2006-11-01 2008-07-17 Luzbetak Mark A Self returning contamination barrier
US8187227B2 (en) * 2006-11-01 2012-05-29 Medela Holding Ag Self returning contamination barrier
USD773643S1 (en) 2006-11-01 2016-12-06 Medela Holding Ag Self returning contamination barrier
US9814809B2 (en) 2006-11-01 2017-11-14 Medela Holding Ag Self returning contamination barrier
US11642441B2 (en) 2006-11-01 2023-05-09 Medela Holding Ag Self returning contamination barrier

Also Published As

Publication number Publication date
AT278955B (de) 1970-02-25
FR1535064A (fr) 1968-08-02
DE1590170B2 (fr) 1970-04-02
SE345338B (fr) 1972-05-23
GB1196005A (en) 1970-06-24
DE1590170A1 (fr) 1970-04-02

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