EP0501759A1 - Appareil de commutation répondant à deux conditions - Google Patents

Appareil de commutation répondant à deux conditions Download PDF

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Publication number
EP0501759A1
EP0501759A1 EP92301587A EP92301587A EP0501759A1 EP 0501759 A1 EP0501759 A1 EP 0501759A1 EP 92301587 A EP92301587 A EP 92301587A EP 92301587 A EP92301587 A EP 92301587A EP 0501759 A1 EP0501759 A1 EP 0501759A1
Authority
EP
European Patent Office
Prior art keywords
disc
pressure
responsive
switch
movable contact
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Withdrawn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
EP92301587A
Other languages
German (de)
English (en)
Inventor
Youn H. Ting
Werner Strasser
Richard T. Gordon
John T. Hancock
Bryan C. Jansen
John A. Haug
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.)
Texas Instruments Inc
Original Assignee
Texas Instruments Inc
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
Priority claimed from US07/742,131 external-priority patent/US5121094A/en
Application filed by Texas Instruments Inc filed Critical Texas Instruments Inc
Publication of EP0501759A1 publication Critical patent/EP0501759A1/fr
Withdrawn legal-status Critical Current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
    • H01H35/34—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by diaphragm
    • H01H35/343—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by diaphragm by snap acting diaphragm
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
    • H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting

Definitions

  • This invention relates generally to electric switches and more specifically to electric switches which are responsive separately to two different conditions.
  • a temperature responsive electric switch in heat transfer relationship with selected portions of a compressor apparatus such as the compressor shell.
  • a temperature responsive electric switch of this type is shown and described in U.S. Patent No. 3,416,115 also assigned to the assignee of the present invention.
  • a switch is described having a snap acting thermostatic disc thermally coupled to a thermally conductive surface which in turn is mounted in heat transfer relation with a surface whose temperature is being monitored, i.e. the compressor shell.
  • the disc is adapted to move from a first convex or concave configuration to the opposite concave, convex configuration, upon reaching a selected temperature with its motion transferred through a motion transfer pin to a movable contact arm of the switch to either open or close an electrical circuit.
  • Another object of the invention is the provision of an electric switch responsive separately to two different conditions which is reliable yet economical to produce.
  • an electric switch having stationary and movable contact means is mounted in a cavity formed in a base member.
  • a motion transfer pin guide is received on the base and is provided with a recess formed on an outer surface to accommodate a first, snap acting disc such as a thermostatic disc.
  • a motion transfer pin is slidably mounted in a bore of the guide between the first disc and the movable contact means.
  • the base and guide are received in a tubular metallic housing which is hermetically attached to a second snap acting disc, such as a pressure responsive diaphragm, and an annular disc support.
  • a second pin is received in the bore of the annular support and extends between the diaphragm and the first disc.
  • a disc retainer is mounted on the pin guide and extends into the recess a selected distance such that the first disc, in its normal unactuated convex configuration, is permitted to move freely between the floor of the recess and the disc retainer.
  • the housing is formed with a pressure port so that the diaphragm can be placed in direct communication with a fluid pressure source.
  • the second disc or diaphragm will move from its unactuated convex configuration to an opposite concave configuration transferring its motion through the second pin to the first disc. Since the first disc is free to move within its prescribed limits it moves-against the first pin and transfers motion to the movable contact means to open the switch circuit.
  • thermostatic disc with the compressor shell including extending the housing and forming it into a tubular port configuration for direct attachment to an aperture in the compressor shell and extending the housing or pressure disc support outwardly to form a welding plate for direct attachment to the compressor shell.
  • Another embodiment shows an outward extension on a portion of the housing removed from the pressure sensor to minimize potential deleterious affects on calibration caused by heat associated with welding of the switch housing to the compressor shell.
  • An alternative embodiment employs concentric motion transfer pin members comprising a solid pin slidably mounted within a tubular pin which in turn is slidably mounted in a bore of a guide member.
  • the solid pin extends between a pressure disc and the movable contact means through an aperture in the thermostatic disc and the tubular pin extends between the thermostatic disc and the movable contact means.
  • the pressure sensing function may be accomplished with a single pressure disc or a stack of several pressure discs depending upon the desired actuation pressures.
  • Another alternative embodiment is particularly adapted for use to be responsive to low pressure or partial vacuum conditions as well as to temperature conditions.
  • the pressure responsive disc in its normal condition is bowed inwardly maintaining the movable contact, through a temperature responsive disc assembly, in the closed condition.
  • the disc Upon a selected decrease in sensed pressure, e.g. upon being exposed to a selected partial vacuum, the disc will snap outwardly causing the spring bias in the movable contact arm to open the switch.
  • temperature responsive disc will snap which will also allow the spring bias in the movable arm to open the switch.
  • switch 10 comprises a cylindrical cup shaped base member 12 formed of a conventional molded electrically insulative material, and is formed with apertures 14, 16 for reception therein of terminal members 18 and 20 respectively.
  • Movable contact arm 22 formed of electrically conductive material having good spring characteristics, such as beryllium copper, is cantilever mounted to the free distal end of terminal 18 in any conventional manner as by welding. Arm 22 is preferably formed with a dimple 26 for engagement with a motion transfer pin to be described below. Arm 22 mounts on its free end a movable contact 28 which is normally biased into engagement with the distal end portion 30 of terminal 20 which end portion is bent approximately 90° to extend into the cavity 32 formed within base member 12.
  • a generally circular pin guide 34 of suitable electrically insulative material is disposed on the free distal end of the base member sidewall 36.
  • a bore 38 is formed through pin guide 34 in alignment with dimple 26 of movable contact arm 22.
  • Pin guide 34 also has a recess 40 formed therein for reception of a temperature responsive thermostatic disc 42.
  • a thermally conductive disc retainer 44 is received on the annular shaped top surface of pin guide 34 and is also shaped as an annulus having disc retaining feet 46 depending down into the recess at a plurality of locations around the outer periphery of the recess to define an upward limit of the motion of disc 42 which can move from and to floor 48 of the recess. It will be appreciated that feet 46 could be a continuous circular member as well as a plurality of discrete feet.
  • a first or lower pin 50 is slidably received in bore 38 and extends generally between dimple 26 and thermostatic disc 42.
  • Support 52 is bent into a saucer shaped configuration a selected amount to permit diaphragm 58 to move from the upwardly convex configuration shown in Fig. 1 to an opposite concave configuration.
  • a pressure responsive diaphragm 58 of stainless steel or other suitable material is placed over the disc support 52 with a second or upper motion transfer pin 59 slidably received in bore 54.
  • the diaphragm is formed into a snap acting disc by means known in the art; basically involving forming a curved surface by permanently deforming the diaphragm material.
  • Base member 12 and pin guide 34 are placed within a tubular, metallic housing 60 which is hermetically attached to the outer periphery of disc support 52 and pressure diaphragm 58 as by welding.
  • Housing 60 is provided with a reduced section 61 which fits against an enlarged diameter portion 13 of base member 12 to lock the base member in one direction. The opposite direction is locked by means of the hermetic welding of the housing to the diaphragm and disc support.
  • Housing 60 extends above pressure diaphragm 58 and terminates in an open tubular section 62 which is adapted to be inserted into an aperture of a compressor shell and attached to the shell as by welding with the pressure diaphragm 58 directly exposed to a fluid pressure source within the compressor shell and the temperature responsive disc 42 thermally coupled to the compressor shell via the thermally conductive path including housing 60, disc support 52 and disc retainer 44 as well as via the pressure fluid, pressure diaphragm 58 and disc support 44. Housing 60 extends below base member 12 to provide a well to receive epoxy 64 to provide an environmental seal for the switch cavity.
  • the feet 46 of the disc retainer extend into recess 40 so that a selected distance is provided between feet 46 and floor 48. This distance is selected so that upon a selected increase in pressure exposed to diaphragm/disc 58 when the disc snaps from its upwardly convex configuration as shown in Fig. 1 to its oppositely configured, upwardly concave configuration (not shown) its motion will be transferred through upper pin 59 to temperature responsive disc 42 moving it toward the bottom of the recess and in turn moving lower pin 50 downwardly against dimple 26 to separate movable contact 28 from stationary contact 30.
  • disc 42 will snap from its upwardly convex configuration shown in Fig. 1 to its opposite, upwardly concave configuration with the outer peripheral portions of the disc reacting against feet 44 and the center of the disc transferring its motion through lower pin 50 to dimple 26 to cause movable contact 28 to move out of engagement with stationary contact 30.
  • Figs. 2 and 3 show alternative structure for attaching the switch to a compressor shell including a radially extending flange 66 projecting from housing 60.1 to facilitate welding of switch 10.1 to the compressor shell as shown in Fig. 2.
  • a radial flange 68 has been added to the open tubular section 62 of switch 10.2 which facilitates welding of switch 10.2 to the compressor shell.
  • Figs. 4 and 5 show yet other embodiments for mounting the switch to a compressor shell which provide the further advantage of isolating the heat of the welding operation when attaching the switch housing to the compressor shell, from the pressure sensing portion of the switch and thereby avoid possible calibration drifts which could occur upon being subjected to excessively high temperatures.
  • housing 60.3 is provided with a radially extending flange 70 which extends from the housing below the transition between the full size diameter portion and the reduced diameter portion.
  • Fig. 5 shows switch 10.4 mounted entirely within the compressor shell with housing 60.4 extended beyond the bottom of base member 12 and terminating with outwardly extending radial flange 72 which is readily weldable to the compressor shell.
  • Housing 60.4, preferably formed of cold rolled steel is provided with a plurality of detents 63 which cooperate with enlarged radius portion 13 of base member 12 and a locking spring 74 to prevent motion of base member 12 along with the hermetic welding of the pressure sensor portion of the switch.
  • Clamp rings 76 may also be used if desired for locking the base member within the housing.
  • a switch made in accordance with Fig. 5 has a total height of 1.5 inches, the housing has an outer diameter of 1.25 inches and has the following characteristics:
  • Switch 10.5 comprises a cup shaped base member 12 defining a switch cavity 32, as described above, into which are received terminals 18, 20 (only terminal 18 being shown in the figure).
  • a movable contact member 22′ is mounted at one end on support 18.1, attached to terminal 18, and mounts movable contact 28′ at an opposite end.
  • Movable contact 28′ is adapted to go into and out of engagement with stationary contact 30′ which is mounted on stationary terminal 20.1 attached to terminal 20.
  • a motion transfer guide member 34′ is provided with a centrally located hub 34.1 through which a bore 34.2 extends.
  • a recess 40′ is formed in the outer surface of guide member 34′ and receives therein a thermostatic disc 42′ having a centrally located aperture 42.1.
  • Disc 42′ is retained in recess 40′ during assembly by a disc retainer member 44′ which is formed with a sidewall 44.1 to be discussed below.
  • Disc retainer 44′ is constructed of heat conductive material such as aluminum and serves to conduct heat from housing 60.5 to heat responsive disc 42′.
  • a tubular motion transfer member 80 of suitable electrically insulative material such as ceramic having an outer diameter larger than the aperture in disc 42′ is slidably received in bore 34.2 and extends between movable contact member 22′ and temperature responsive disc 42′.
  • Guide member 34′ is placed on the free distal end portion of the base member 12 sidewalls with sidewall 44.1 crimped beyond the enlarged portion 13 to secure the temperature sensing assembly to base 12.
  • Annular pressure disc support 52′ is provided with a centrally located bore 52.1 and is formed with a recess 52.2 adapted to receive a selected number of pressure responsive discs 58, the particular number of discs being dependent upon the desired actuation pressure.
  • a single disc could be employed for relatively low actuation pressures or a stack of up to five or more discs could be used for higher pressures.
  • Movable member 22′ is preferably formed with a rib 26′ to engage members 80, 84.
  • An outer cap 84 is received over recess 52.2 capturing the pressure responsive discs 58 therein and is welded to annular support 52′ and the lower end of housing 60.5 along their outer peripheries to form an hermetic seal.
  • An aperture 84.1 in cap 84 provides communication between the pressure responsive disc and the pressure source to be monitored.
  • the housing is bent inwardly at selected locations 63 to lock the switch mechanism into housing 60.5.
  • the Fig. 6 embodiment provides a motion transfer mechanism which is easy to assemble yet reliable in operation. It will be understood that the switching logic, i.e. normally closed v. normally open, can be inverted by placing the stationary contact member on the other side of the movable contact member.
  • a pressure and temperature responsive switch particularly adapted for use in sensing low pressure conditions such as partial vacuum along with high temperature conditions is shown.
  • the switch of Fig. 7 is a variation of that shown in Figs. 1-5 with the differences discussed below.
  • the switch is normally closed with pressure responsive disc 86 bowed inwardly against disc support 52 at pressures of a pressure source in communication with disc 86 above a selected level, for example above 12 psi. Should the pressure of the fluid media exposed to disc 86 fall below that level the disc will snap outwardly to the dashed line position shown in the figure.
  • Temperature responsive disc 42 is received in a cage 90 and retained therein by arms 92, the cage being adapted to move up and down, as seen in Fig. 7, within recess 94. As shown in the figure the disc, at temperatures below a selected level, has an inwardly convex configuration. Should the temperature of disc 42 increase to the selected level the disc will snap to its opposite inwardly concave position (not shown).
  • pressure responsive disc 86 will bias pin 59 upwardly against bottom wall 91 of cage 90 biasing cage 90 and temperature responsive disc 42 upwardly which in turn, through pin 50, biases movable arm 22.1 upwardly thereby maintaining movable contact 28.1 in engagement with stationary contact 30.1. If the temperature of temperature responsive disc 42 increases to the selected level the disc will snap to its opposite configuration allowing the bias in movable arm 22.1 to move the arm downwardly along with pin 50 with the contacts moving into the contacts disengaged position.
  • pressure responsive disc 86 will snap to its dashed line position allowing pin 59, and the temperature responsive disc assembly of disc 42 and cage 90 to move downwardly thereby allowing movable arm 22.1 to push pin 50 downwardly and concomitantly the contacts to move into the contacts disengaged position.
  • the sensitivity of the temperature responsive disc assembly can be enhanced by improving the heat conductive path from housing 60.6 to the disc as by forming a plurality of spaced apart arms 52.3 shown in Fig. 8 from pressure disc support 52 and bending them upwardly to define the path of movement of cage 90 in close thermal coupling thereto.

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  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Thermally Actuated Switches (AREA)
  • Switches Operated By Changes In Physical Conditions (AREA)
EP92301587A 1991-02-26 1992-02-25 Appareil de commutation répondant à deux conditions Withdrawn EP0501759A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US66176491A 1991-02-26 1991-02-26
US661764 1991-02-26
US73229991A 1991-07-18 1991-07-18
US732299 1991-07-18
US742131 1991-08-08
US07/742,131 US5121094A (en) 1991-02-26 1991-08-08 Dual condition responsive switch apparatus

Publications (1)

Publication Number Publication Date
EP0501759A1 true EP0501759A1 (fr) 1992-09-02

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EP92301587A Withdrawn EP0501759A1 (fr) 1991-02-26 1992-02-25 Appareil de commutation répondant à deux conditions

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EP (1) EP0501759A1 (fr)
JP (1) JPH04312727A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3702692A1 (fr) * 2019-02-28 2020-09-02 Gerdes Holding GmbH & Co. KG Régulateur de pression de sécurité et chauffe-eau instantané électrique doté d'un tel régulateur de pression de sécurité

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3720090A (en) * 1968-12-30 1973-03-13 Texas Instruments Inc Switch with improved means and method for calibration
US4145588A (en) * 1977-09-29 1979-03-20 Texas Instruments Incorporated Condition responsive apparatus having freely disposed disc
US4581509A (en) * 1984-07-20 1986-04-08 Texas Instruments Incorporated Features of a condition responsive switch
US4652854A (en) * 1985-04-30 1987-03-24 Borg-Warner Corporation Pressure-biased, temperature sensor
GB2185857A (en) * 1986-01-25 1987-07-29 Haden D H Ltd Controls for vessels for heating liquids
EP0272934A2 (fr) * 1986-12-23 1988-06-29 Texas Instruments Incorporated Interrupteur électrique répondant à deux conditions

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3720090A (en) * 1968-12-30 1973-03-13 Texas Instruments Inc Switch with improved means and method for calibration
US4145588A (en) * 1977-09-29 1979-03-20 Texas Instruments Incorporated Condition responsive apparatus having freely disposed disc
US4581509A (en) * 1984-07-20 1986-04-08 Texas Instruments Incorporated Features of a condition responsive switch
US4652854A (en) * 1985-04-30 1987-03-24 Borg-Warner Corporation Pressure-biased, temperature sensor
GB2185857A (en) * 1986-01-25 1987-07-29 Haden D H Ltd Controls for vessels for heating liquids
EP0272934A2 (fr) * 1986-12-23 1988-06-29 Texas Instruments Incorporated Interrupteur électrique répondant à deux conditions

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3702692A1 (fr) * 2019-02-28 2020-09-02 Gerdes Holding GmbH & Co. KG Régulateur de pression de sécurité et chauffe-eau instantané électrique doté d'un tel régulateur de pression de sécurité
WO2020173854A1 (fr) * 2019-02-28 2020-09-03 Gerdes Holding Gmbh & Co. Kg Limiteur de pression de sécurité et chauffe-eau instantané électrique qui en est équipé

Also Published As

Publication number Publication date
JPH04312727A (ja) 1992-11-04

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