US3617665A - Snap-action pressure-sensitive switch with safety feature responsive to contact welding - Google Patents
Snap-action pressure-sensitive switch with safety feature responsive to contact welding Download PDFInfo
- Publication number
- US3617665A US3617665A US882140A US3617665DA US3617665A US 3617665 A US3617665 A US 3617665A US 882140 A US882140 A US 882140A US 3617665D A US3617665D A US 3617665DA US 3617665 A US3617665 A US 3617665A
- Authority
- US
- United States
- Prior art keywords
- switch
- tongue
- contact
- movable
- pressure
- 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
Links
Images
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
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
- D06F37/00—Details specific to washing machines covered by groups D06F21/00 - D06F25/00
- D06F37/42—Safety arrangements, e.g. for stopping rotation of the receptacle upon opening of the casing door
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
- D06F39/00—Details of washing machines not specific to a single type of machines covered by groups D06F9/00 - D06F27/00
- D06F39/08—Liquid supply or discharge arrangements
- D06F39/087—Water level measuring or regulating devices
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H3/00—Mechanisms for operating contacts
- H01H3/001—Means for preventing or breaking contact-welding
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S200/00—Electricity: circuit makers and breakers
- Y10S200/42—Contact welding considerations
Definitions
- the pressure switch comprises a toggle switch in which a flexible switch tongue is moved by a pressure-actuated diaphragm against the force of a return spring, and a contact-carrying flexible switch blade, connected to the blade tongue, through an overcenter spring, is moved by snap-action in one direction as the blade tongue moves through the overcenter position in the opposite direction:
- a contact is movable by the switch tongue to engage a stationary contact after a predetermined movement of the switch tongue past the overcenter position, the switch tongue being movable despite the possibility of welding of the toggle switch contacts. Closure of the safety switch by the switch tongue in this way can be used to energize a pump in the event of failure of a water valve to close or to energize a water valve otherwise prevented from energization by welding of two of the toggle switch contacts.
- This invention relates to pressure-sensitive switch devices (normally referred to as pressure switches), in particular for use in washing machines to control the level of water in the washtub or to control other functions in dependence upon such level.
- a conventional pressure switch for a washing machine comprises a casing housing a switch blade and a switch tongue anchored at a common point, the outer end of the switch tongue being connected through a toggle or overcenter spring to the outer end portion of the switch blade so that movement of the switch tongue in either direction through an overcenter position snaps the switch blade in the opposite directions, the switch blade being movable between a stationary trip contact and a stationary reset contact.
- the switch tongue is biased in one direction by a variable force-calibrating spring and in the opposite direction by a pressure-sensitive diaphragm.
- the reset contact of the switch is connected to a solenoidoperated water valve so that when the water level, and hence the pressure on the diaphragm, increases to a predetermined value, the switch blade is tripped off the reset contact to deenergize and thus close the water valve. Engagement of the switch blade with the trip contact can be used to energize and electric water heater. Conversely when the water level has fallen to a predetermined value, the switch blade is tripped out of engagement with the trip contact and on to the reset contact thereby opening the water valve.
- the pressure switch can incorporate two or more separate switch assemblies with? separate trip and reset contacts, each switch assembly being operable independently by the diaphragm to switch over at different pressure levels.
- two level, or even three level, switches can be made by varying the number of switch assemblies.
- a fault in the water control circuit can lead to overflow of the washtub. This fault usually occurs as a result of the water valve failing to close when deenergized, but it can also result from the switch blade becoming welded to the reset contact preventing deenergization of the water valve.
- An object of the present invention is to provide a pressure switch in which failure of the water control circuit to terminate the water supply when the water level has risen to predetermined value is counteracted.
- Another object of the invention is to provide a pressure switch with a safety arrangement for preventing the water level in the tub from falling to such a low level that a waterheating electric element would no longer be immersed in water.
- a conventional pressure switch is accordingly modified to providing a safety switch in the form of a contact on a member movable with the flexible switch tongue, and a stationary contact arranged to be engaged by the movable contact following a predetermined movement of the switch tongue past the overcenter position under or against the force of an additional spring.
- This force can be varied. Since movement of the switch tongue controls movement of the switch blade, but is only partly effected by movement of the switch blade, the switch tongue can move to close the safety switch despite welding of a stationary contact to the movable contact of the blade.
- FIG. 1 is a section through a pressui'e switch in accordance with the invention, for a washing machine, and
- FIGS. 2, 3, 4 and 5 are diagrammatic illustrations of the moving parts of the switch of FIG. I in various operational positions.
- the pressure switch comprises a housing 10 which is divided by a flexible diaphragm 11 into a pressure chamber 8 connected to the tub of a washing machine, and a switch chamber 9 for containing the switch mechanism.
- two separate switch assemblies are provided only one of which is shown.
- This comprises a flexible switch blade 12 supporting a contact 31 for movement therewith between a stationary but adjustable reset contact 32 and a stationary trip contact 33, and a flexible switch tongue l3fixed at the same anchorage point as the switch blade and connected at its outer end to the switch blade through a toggle or overcenter spring 14.
- a switch-actuating lever 15, extending alongside the switch tongue and con nected to the switch tongue for movement therewith, is biased by an adjustable calibrating spring 16 in a sense to keep the switch blade on the reset contact 32.
- the arrangement for overcoming the possibility of the water valve 6 failing to close (overflow safety control), or the switch blade becoming welded to the reset contact (heater safety control), comprises a pin 22 supported for longitudinal movement in the wall of the housing on a biasing spring 23, whose force is adjustable by a screw 24, the pin being aligned with an abutment 25 on the switch lever so that as the switch lever is moved toward the pin past the switch-tripping position, the abutment comes into engagement with the pin and commences to move the pin against the force of its biasing spring.
- the switch lever supports at its outer end a safety switch contact 26 which is cooperable with a stationary safety switch contact 27 in the wall of the housing and connected to the water pump 7 of the machine.
- the movable safety switch contact engages thestationary safety switch contact to close the safety switch and thereby energize the pump for pumping water out of the washing machine tub (see FIG. 4).
- Variation of the bias of the pin-biasing spring 23 varies the water level at which the safety switch energizes the pump to avoid overflow. This spring adjustment however does not affect the normal levels at which the pressure switch operates as determined by the position of trip and reset contacts. Moreover, the intermittent operation of the pump will serve as a warning signal.
- Such a pressure switch even using only one overcenter switch assembly, provides three-level switch operation, i.e. trip level, reset level, and a safety level.
- contacts 26, 27, 28 and 29 have been illustrated as actual contact buttons secured to the metal members on which they are supported, it will be apparent that since these contacts serve only an emergency function it is not necessary to provide contact buttons, and mere engagement between the metal members themselves will suffice to complete a circuit.
- a toggle switch having a switch tongue movable through an overcenter position
- a safety switch arranged to be closed by further movement of the switch tongue in the same direction after passing said overcenter position.
- a toggle switch having a switch blade movable to move a switch contact between a first stationary contact and a second stationary contact a switch tongue and a toggle spring connected between the switch tongue and the switch blade for moving the switch blade with a snapaction in one direction as the switch tongue moves in the opposite direction through an overcenter position;
- a pressure-sensitive member operable to move the switch tongue against the force of a return spring
- a switch device according to claim 2 wherein said further movable contact is mounted on a member connected for movement with said switch tongue.
- a switch device including a further spring for opposing movement of said further movable contact towards the third stationary contact and arranged to come into operation only after the switch tongue has passed said overcenter position.
- a switch device having means for varying the force of said further spring.
- a switch device wherein said further movable contact is movable, in response to increasing pressure, into contact with the third stationary contact despite the switch contact being welded to one of said first and second stationary contacts.
- a toggle switch having a switch blade movable to move a switch contact between a first stationary contact and a second stationary contact a switch tongue and a toggle spring connected between the switch tongue and the switch blade for moving the switch blade with a snapaction in one direction as the switch tongue moves in the opposite direction through an overcenter position;
- a pressure-sensitive member operable to move the switch tongue against the force of a return spring
Landscapes
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Switches Operated By Changes In Physical Conditions (AREA)
- Push-Button Switches (AREA)
- Rotary Switch, Piano Key Switch, And Lever Switch (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB5954068 | 1968-12-13 | ||
AU16236/70A AU460986B2 (en) | 1968-12-13 | 1970-06-11 | Improvements in and relating to pressure switches, in particular for washing machines |
Publications (1)
Publication Number | Publication Date |
---|---|
US3617665A true US3617665A (en) | 1971-11-02 |
Family
ID=25616265
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US882140A Expired - Lifetime US3617665A (en) | 1968-12-13 | 1969-12-04 | Snap-action pressure-sensitive switch with safety feature responsive to contact welding |
Country Status (4)
Country | Link |
---|---|
US (1) | US3617665A (xx) |
AU (1) | AU460986B2 (xx) |
DE (1) | DE1962486B2 (xx) |
GB (1) | GB1228400A (xx) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3735069A (en) * | 1971-01-12 | 1973-05-22 | Danfoss As | Snap-action electric switch |
US3839609A (en) * | 1972-09-27 | 1974-10-01 | Controls Co Of America | Pressure switch having pressure hose connection through case and diaphragm |
US3964004A (en) * | 1974-02-25 | 1976-06-15 | Mertler Charles S | Thermostatic switch with standby contacts |
US4356365A (en) * | 1980-10-24 | 1982-10-26 | Edison International, Inc. | Air operated DC switch |
US4479039A (en) * | 1983-10-26 | 1984-10-23 | Robert Shaw Controls Company | Electrical switch construction and method of making the same |
US4937549A (en) * | 1989-10-02 | 1990-06-26 | General Electric Company | Condition responsive switching apparatus |
US5101188A (en) * | 1989-10-02 | 1992-03-31 | General Electric Company | Condition responsive switching apparatus |
US20060219538A1 (en) * | 2005-03-31 | 2006-10-05 | Robertshaw Controls Company | Simultaneous control of multiple liquid level settings in a diaphragm valve, using a single rotatable control shaft |
US20070235302A1 (en) * | 2006-03-29 | 2007-10-11 | Steve Severson | High pressure switch with isolated contacts |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IT1145105B (it) * | 1981-09-22 | 1986-11-05 | Mario Turatti | Trasmettitore elettrico di pressione utilizzabile per comandare segnalatori elettrici della pressione dell olio nel circuito di lubrificazione di motori a combustione interna |
US4464551A (en) * | 1982-05-14 | 1984-08-07 | General Electric Company | Electric circuit controlling device and method of operating same |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2484112A (en) * | 1944-09-29 | 1949-10-11 | Metals & Controls Corp | Time-delay circuit controller |
US2792466A (en) * | 1954-06-17 | 1957-05-14 | Ranco Inc | Control apparatus |
US2872540A (en) * | 1958-02-24 | 1959-02-03 | Bendix Aviat Corp | Governor switch |
US3133433A (en) * | 1962-05-24 | 1964-05-19 | Controls Co Of America | Automatic washing machine with pressure switch means |
US3193650A (en) * | 1962-02-26 | 1965-07-06 | King Seeley Thermos Co | Condition responsive switch with weld breaking means |
US3235692A (en) * | 1962-11-30 | 1966-02-15 | Ametek Inc | Condition responsive sequence switch |
US3352983A (en) * | 1965-06-29 | 1967-11-14 | Controls Co Of America | Pressure switch and electrical switch therefor |
-
1968
- 1968-12-13 GB GB5954068A patent/GB1228400A/en not_active Expired
-
1969
- 1969-12-04 US US882140A patent/US3617665A/en not_active Expired - Lifetime
- 1969-12-12 DE DE1962486A patent/DE1962486B2/de active Pending
-
1970
- 1970-06-11 AU AU16236/70A patent/AU460986B2/en not_active Expired
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2484112A (en) * | 1944-09-29 | 1949-10-11 | Metals & Controls Corp | Time-delay circuit controller |
US2792466A (en) * | 1954-06-17 | 1957-05-14 | Ranco Inc | Control apparatus |
US2872540A (en) * | 1958-02-24 | 1959-02-03 | Bendix Aviat Corp | Governor switch |
US3193650A (en) * | 1962-02-26 | 1965-07-06 | King Seeley Thermos Co | Condition responsive switch with weld breaking means |
US3133433A (en) * | 1962-05-24 | 1964-05-19 | Controls Co Of America | Automatic washing machine with pressure switch means |
US3235692A (en) * | 1962-11-30 | 1966-02-15 | Ametek Inc | Condition responsive sequence switch |
US3352983A (en) * | 1965-06-29 | 1967-11-14 | Controls Co Of America | Pressure switch and electrical switch therefor |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3735069A (en) * | 1971-01-12 | 1973-05-22 | Danfoss As | Snap-action electric switch |
US3839609A (en) * | 1972-09-27 | 1974-10-01 | Controls Co Of America | Pressure switch having pressure hose connection through case and diaphragm |
US3964004A (en) * | 1974-02-25 | 1976-06-15 | Mertler Charles S | Thermostatic switch with standby contacts |
US4356365A (en) * | 1980-10-24 | 1982-10-26 | Edison International, Inc. | Air operated DC switch |
US4479039A (en) * | 1983-10-26 | 1984-10-23 | Robert Shaw Controls Company | Electrical switch construction and method of making the same |
US4937549A (en) * | 1989-10-02 | 1990-06-26 | General Electric Company | Condition responsive switching apparatus |
US5101188A (en) * | 1989-10-02 | 1992-03-31 | General Electric Company | Condition responsive switching apparatus |
US20060219538A1 (en) * | 2005-03-31 | 2006-10-05 | Robertshaw Controls Company | Simultaneous control of multiple liquid level settings in a diaphragm valve, using a single rotatable control shaft |
US7511239B2 (en) * | 2005-03-31 | 2009-03-31 | Robertshaw Controls Company | Simultaneous control of multiple liquid level settings in a diaphragm valve, using a single rotatable control shaft |
US20070235302A1 (en) * | 2006-03-29 | 2007-10-11 | Steve Severson | High pressure switch with isolated contacts |
US7348509B2 (en) * | 2006-03-29 | 2008-03-25 | Micro Pneumatic Logic, Inc. | High pressure switch with isolated contacts |
Also Published As
Publication number | Publication date |
---|---|
AU460986B2 (en) | 1975-04-21 |
GB1228400A (xx) | 1971-04-15 |
AU1623670A (en) | 1971-12-16 |
DE1962486A1 (de) | 1970-07-02 |
DE1962486B2 (de) | 1973-10-18 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: CONTROLS COMPANY OF AMERICA, 9655 W. SORENG AVENUE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:SINGER COMPANY, THE;REEL/FRAME:004505/0515 Effective date: 19860110 |
|
AS | Assignment |
Owner name: EATON CORPORATION, EATON CENTER, 1111 SUPERIOR AVE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:CONTROLS COMPANY OF AMERICA;REEL/FRAME:004614/0433 Effective date: 19861002 |